• Docs and Samples
  • Docs
  • Samples

    • Table Of Contents

    Welcome link

    Welcome to DragonRuby Game Toolkit!

    The information contained here is all available in your the zip file at ./docs/docs.html. You can browse the docs in a local website by starting up DragonRuby and going to http://localhost:9001.

    Tips for Learning DragonRuby Game Toolkit link

    The following tips will help you learn the DragonRuby quickly.

    Tip #1: Join the Community link

    Our Discord server is extremely supportive and helpful. It's the best place to get answers to your questions. The developers of DragonRuby are also on this server if you have any feedback or bug reports.

    The Link to Our Discord Server is: http://discord.dragonruby.org.

    The News Letter will keep you in the loop with regards to current DragonRuby Events: http://dragonrubydispatch.com.

    Tip #2: Read the Book link

    Brett Chalupa (one of our community members) has written a book to help you get started: https://book.dragonriders.community/

    Tip #3: Watch the Tutorial Video link

    Here are some videos to help you get the lay of the land.

    1. Building Tetris - Part 1: https://youtu.be/xZMwRSbC4rY
    2. Building Tetris - Part 2: https://youtu.be/C3LLzDUDgz4

    Tip #4: Go Through the Sample Apps in Order link

    The sample apps are located in the ./samples directory. The samples are ordered by increasing difficulty and cover all aspects of the game engine.

    Getting Started Tutorial link

    This is a tutorial written by Ryan C Gordon (a Juggernaut in the industry who has contracted to Valve, Epic, Activision, and EA... check out his Wikipedia page: https://en.wikipedia.org/wiki/Ryan_C._Gordon).

    Introduction link

    Welcome!

    Here's just a little push to get you started if you're new to programming or game development.

    If you want to write a game, it's no different than writing any other program for any other framework: there are a few simple rules that might be new to you, but more or less programming is programming no matter what you are building.

    Did you not know that? Did you think you couldn't write a game because you're a "web guy" or you're writing Java at a desk job? Stop letting people tell you that you can't, because you already have everything you need.

    Here, we're going to be programming in a language called "Ruby." In the interest of full disclosure, I (Ryan Gordon) wrote the C parts of this toolkit and Ruby looks a little strange to me (Amir Rajan wrote the Ruby parts, discounting the parts I mangled), but I'm going to walk you through the basics because we're all learning together, and if you mostly think of yourself as someone that writes C (or C++, C#, Objective-C), PHP, or Java, then you're only a step behind me right now.

    Prerequisites link

    Here's the most important thing you should know: Ruby lets you do some complicated things really easily, and you can learn that stuff later. I'm going to show you one or two cool tricks, but that's all.

    Do you know what an if statement is? A for-loop? An array? That's all you'll need to start.

    The Game Loop link

    Ok, here are few rules with regards to game development with GTK:

    That's an entire video game in one run-on sentence.

    Here's that function. You're going to want to put this in mygame/app/main.rb, because that's where we'll look for it by default. Load it up in your favorite text editor. 

    def tick args
  args.outputs.labels << [580, 400, 'Hello World!']
end

    Now run dragonruby ...did you get a window with "Hello World!" written in it? Good, you're officially a game developer!

    Breakdown Of The tick Method link

    mygame/app/main.rb, is where the Ruby source code is located. This looks a little strange, so I'll break it down line by line. In Ruby, a '#' character starts a single-line comment, so I'll talk about this inline. 

    # This "def"ines a function, named "tick," which takes a single argument
# named "args". DragonRuby looks for this function and calls it every
# frame, 60 times a second. "args" is a magic structure with lots of
# information in it. You can set variables in there for your own game state,
# and every frame it will updated if keys are pressed, joysticks moved,
# mice clicked, etc.
def tick args

  # One of the things in "args" is the "outputs" object that your game uses
  # to draw things. Afraid of rendering APIs? No problem. In DragonRuby,
  # you use arrays to draw things and we figure out the details.
  # If you want to draw text on the screen, you give it an array (the thing
  # in the [ brackets ]), with an X and Y coordinate and the text to draw.
  # The "<<" thing says "append this hash onto the list of them at
  # args.outputs.labels)
  args.outputs.labels << { x: 580, y: 400, text: 'Hello World!' }
end

    Once your tick function finishes, we look at all the arrays you made and figure out how to draw it. You don't need to know about graphics APIs. You're just setting up some arrays! DragonRuby clears out these arrays every frame, so you just need to add what you need _right now_ each time.

    Rendering A Sprite link

    Now let's spice this up a little.

    We're going to add some graphics. Each 2D image in DragonRuby is called a "sprite," and to use them, you just make sure they exist in a reasonable file format (png, jpg, gif, bmp, etc) and specify them by filename. The first time you use one, DragonRuby will load it and keep it in video memory for fast access in the future. If you use a filename that doesn't exist, you get a fun checkerboard pattern!

    There's a "dragonruby.png" file included, just to get you started. Let's have it draw every frame with our text: 

    def tick args
  args.outputs.labels  << { x: 580, y: 400, text: 'Hello World!' }
  args.outputs.sprites << { x: 576, y: 100, w: 128, h: 101, path: 'dragonruby.png' }
end

    (Pro Tip: you don't have to restart DragonRuby to test your changes; when you save main.rb, DragonRuby will notice and reload your program.)

    That .sprites line says "add a sprite to the list of sprites we're drawing, and draw it at position (576, 100) at a size of 128x101 pixels". You can find the image to draw at dragonruby.png.

    Coordinate System and Virtual Canvas link

    Quick note about coordinates: (0, 0) is the bottom left corner of the screen, and positive numbers go up and to the right. This is more "geometrically correct," even if it's not how you remember doing 2D graphics, but we chose this for a simpler reason: when you're making Super Mario Brothers and you want Mario to jump, you should be able to add to Mario's y position as he goes up and subtract as he falls. It makes things easier to understand.

    Also: your game screen is _always_ 1280x720 pixels. If you resize the window, we will scale and letterbox everything appropriately, so you never have to worry about different resolutions.

    Ok, now we have an image on the screen, let's animate it: 

    def tick args
  args.state.rotation  ||= 0

  args.state.rotation  -= 1

  args.outputs.labels  << { x: 580, y: 400, text: 'Hello World!' }
  args.outputs.sprites << { x: 576,
                            y: 100,
                            w: 128,
                            h: 101,
                            path: 'dragonruby.png',
                            angle: args.state.rotation }
end

    Now you can see that this function is getting called a lot!

    Game State link

    Here's a fun Ruby thing: args.state.rotation ||= 0 is shorthand for "if args.state.rotation isn't initialized, set it to zero." It's a nice way to embed your initialization code right next to where you need the variable.

    args.state is a place you can hang your own data. It's an open data structure that allows you to define properties that are arbitrarily nested. You don't need to define any kind of class.

    In this case, the current rotation of our sprite, which is happily spinning at 60 frames per second. If you don't specify rotation (or alpha, or color modulation, or a source rectangle, etc), DragonRuby picks a reasonable default, and the array is ordered by the most likely things you need to tell us: position, size, name.

    There Is No Delta Time link

    One thing we decided to do in DragonRuby is not make you worry about delta time: your function runs at 60 frames per second (about 16 milliseconds) and that's that. Having to worry about framerate is something massive triple-AAA games do, but for fun little 2D games? You'd have to work really hard to not hit 60fps. All your drawing is happening on a GPU designed to run Fortnite quickly; it can definitely handle this.

    Since we didn't make you worry about delta time, you can just move the rotation by 1 every time and it works without you having to keep track of time and math. Want it to move faster? Subtract 2.

    Handling User Input link

    Now, let's move that image around. 

    def tick args
  args.state.rotation ||= 0
  args.state.x ||= 576
  args.state.y ||= 100

  if args.inputs.mouse.click
    args.state.x = args.inputs.mouse.x - 64
    args.state.y = args.inputs.mouse.y - 50
  end

  args.outputs.labels  << { x: 580, y: 400, text: 'Hello World!' }
  args.outputs.sprites << { x: args.state.x,
                            y: args.state.y,
                            w: 128,
                            h: 101,
                            path: 'dragonruby.png',
                            angle: args.state.rotation }

  args.state.rotation -= 1
end

    Everywhere you click your mouse, the image moves there. We set a default location for it with args.state.x ||= 576, and then we change those variables when we see the mouse button in action. You can get at the keyboard and game controllers in similar ways.

    Coding On A Raspberry Pi link

    We have only tested DragonRuby on a Raspberry Pi 3, Models B and B+, but we believe it _should_ work on any model with comparable specs.

    If you're running DragonRuby Game Toolkit on a Raspberry Pi, or trying to run a game made with the Toolkit on a Raspberry Pi, and it's really really slow-- like one frame every few seconds--then there's likely a simple fix.

    You're probably running a desktop environment: menus, apps, web browsers, etc. This is okay! Launch the terminal app and type: 

    sudo raspi-config

    It'll ask you for your password (if you don't know, try "raspberry"), and then give you a menu of options. Find your way to "Advanced Options", then "GL Driver", and change this to "GL (Full KMS)" ... not "fake KMS," which is also listed there. Save and reboot. In theory, this should fix the problem.

    If you're _still_ having problems and have a Raspberry Pi 2 or better, go back to raspi-config and head over to "Advanced Options", "Memory split," and give the GPU 256 megabytes. You might be able to avoid this for simple games, as this takes RAM away from the system and reserves it for graphics. You can also try 128 megabytes as a gentler option.

    Note that you can also run DragonRuby without X11 at all: if you run it from a virtual terminal it will render fullscreen and won't need the "Full KMS" option. This might be attractive if you want to use it as a game console sort of thing, or develop over ssh, or launch it from RetroPie, etc.

    Conclusion link

    There is a lot more you can do with DragonRuby, but now you've already got just about everything you need to make a simple game. After all, even the most fancy games are just creating objects and moving them around. Experiment a little. Add a few more things and have them interact in small ways. Want something to go away? Just don't add it to args.output anymore.

    Starting a New DragonRuby Project link

    The DragonRuby zip that contains the engine is a complete, self contained project structure. To create a new project, unzip the zip file again in its entirety and use that as a starting point for another game. This is the recommended approach to starting a new project.

    The DragonRuby binary/package is designed to be committed in its entirety with your source code (it’s why we keep it small). This protects the “shelf life” for commercial games. 3 years from now, we might be on a vastly different version of the engine. But you know that the code you’ve written will definitely work with the version that was committed to source control.

    It's strongly recommended that you do NOT keep DragonRuby Game Toolkit in a shared location and instead unzip a clean copy for every game (and commit everything to source control).

    File access functions are sandoxed and assume that the dragonruby binary lives alongside the game you are building. Do not expect file access functions to return correct values if you are attempting to run the dragonruby binary from a shared location. It's recommended that the directory structure contained in the zip is not altered and games are built using that starting directory structure.

    Considerations For Public Git Repositories link

    You can open source your game's code given the following options.

    Option 1 (Recommended) link

    Your public repository needs only to contain the contents of ./mygame. This approach is the cleanest and doesn't require your .gitignore to be polluted with DragonRuby specific files.

    Option 2 (Restrictions Apply) link

    IMPORTANT: Do NOT commit dragonruby-publish(.exe), or dragonruby-bind(.exe). 

    dragonruby
dragonruby.exe
dragonruby-publish
dragonruby-publish.exe
dragonruby-bind
dragonruby-bind.exe
/tmp/
/builds/
/logs/
/samples/
/docs/
/.dragonruby/

    If you'd like people who do not own a DragonRuby license to run your game, you may include the dragonruby(.exe) binary within the repo. This permission is granted in good-faith and can be revoked if abused.

    Considerations For Private Git Repos link

    The following .gitignore should be used for private repositories (commercial games). 

    /tmp/
/logs/

    You'll notice that everything else is committed to source control (even the ./samples, ./docs, and ./builds directory).

    Deploying To Itch.io link

    Once you've built your game, you're all set to deploy! Good luck in your game dev journey and if you get stuck, come to the Discord channel!

    Creating Your Game Landing Page link

    Log into Itch.io and go to https://itch.io/game/new.

    You can fill out all the other options later.

    Update Your Game's Metadata link

    Point your text editor at mygame/metadata/game_metadata.txt and make it look like this:

    NOTE: Remove the # at the beginning of each line. 

    devid=bob
devtitle=Bob The Game Developer
gameid=mygame
gametitle=My Game
version=0.1

    The devid property is the username you use to log into Itch.io. The devtitle is your name or company name (it can contain spaces). The gameid is the Project URL value. The gametitle is the name of your game (it can contain spaces). The version can be any major.minor number format.

    Building Your Game For Distribution link

    Open up the terminal and run this from the command line: 

    ./dragonruby-publish --only-package mygame

    (if you're on Windows, don't put the "./" on the front. That's a Mac and Linux thing.)

    A directory called ./build will be created that contains your binaries. You can upload this to Itch.io manually.

    Browser Game Settings link

    For the HTML version of your game, the following configuration is required for your game to run correctly:

    For subsequent updates you can use an automated deployment to Itch.io: 

    ./dragonruby-publish mygame

    DragonRuby will package _and publish_ your game to itch.io! Tell your friends to go to your game's very own webpage and buy it!

    If you make changes to your game, just re-run dragonruby-publish and it'll update the downloads for you.

    Consider Adding Pause When Game is In Background link

    It's a good idea to pause the game if it doesn't have focus. Here's an example of how to do that 

    def tick args
  # if the keyboard doesn't have focus, and the game is in production mode, and it isn't the first tick
  if !args.inputs.keyboard.has_focus && args.gtk.production && args.state.tick_count != 0
    args.outputs.background_color = [0, 0, 0]
    args.outputs.labels << { x: 640,
                             y: 360,
                             text: "Game Paused (click to resume).",
                             alignment_enum: 1,
                             r: 255, g: 255, b: 255 }
    # consider setting all audio volume to 0.0
  else
    # perform your regular tick function
  end
end

    If you want your game to run at full speed even when it's in the background, add the following line to mygame/metadata/cvars.txt: 

    renderer.background_sleep=0

    Consider Adding a Request to Review Your Game In-Game link

    Getting reviews of your game are extremely important and it's recommended that you put an option to review within the game itself. You can use args.gtk.open_url plus a review URL. Here's an example: 

    def tick args
  # render the review button
  args.state.review_button ||= { x: 640 - 50,
                                 y: 360 - 25,
                                 w: 100,
                                 h: 50,
                                 path: :pixel,
                                 r: 0,
                                 g: 0,
                                 b: 0 }
  args.outputs.sprites << args.state.review_button
  args.outputs.labels << { x: 640, y: 360, anchor_x: 0.5, anchor_y: 0.5, text: "Review" }

  # check to see if the review button was clicked
  if args.inputs.mouse.intersect_rect? args.state.review_button
    # open platform specific review urls
    if args.gtk.platform? :ios
      # your app id is provided at Apple's Developer Portal (numeric value)
      args.gtk.openurl "itms-apps://itunes.apple.com/app/idYOURGAMEID?action=write-review"
    elsif args.gtk.platform? :android
      # your app id is the name of your android package
      args.gtk.openurl "https://play.google.com/store/apps/details?id=YOURGAMEID"
    elsif args.gtk.platform? :web
      # if they are playing the web version of the game, take them to the purchase page on itch
      args.gtk.openurl "https://amirrajan.itch.io/YOURGAMEID/purchase"
    else
      # if they are playing the desktop version of the game, take them to itch's rating page
      args.gtk.openurl "https://amirrajan.itch.io/YOURGAMEID/rate?source=game"
    end
  end
end

    Deploying To Mobile Devices link

    If you have a Pro subscription, you also have the capability to deploy to mobile devices.

    Deploying to iOS link

    To deploy to iOS, you need to have a Mac running MacOS Catalina, an iOS device, and an active/paid Developer Account with Apple. From the Console type: $wizards.ios.start and you will be guided through the deployment process.

    Deploying to Android link

    To deploy to Android, you need to have an Android emulator/device, and an environment that is able to run Android SDK. dragonruby-publish will create an APK for you. From there, you can sign the APK and install it to your device. The signing and installation procedure varies from OS to OS. Here's an example of what the command might look like: 

    # generating a keystore
keytool -genkey -v -keystore APP.keystore -alias mygame -keyalg RSA -keysize 2048 -validity 10000

# deploying to a local device/emulator
apksigner sign --min-sdk-version 21 --ks ./profiles/mygame.keystore ./builds/APP-android.apk
adb install ./builds/APP-android.apk
# read logs of device
adb logcat -e mygame

# signing for Google Play
apksigner sign --min-sdk-version 33 --ks ./profiles/APP.keystore ./builds/APP-googleplay.aab

    Deploying To Steam link

    If you have a Indie or Pro subscription, you also get streamlined deployment to Steam via dragonruby-publish. Please note that games developed using the Standard license can deploy to Steam using the Steamworks toolchain https://partner.steamgames.com/doc/store/releasing.

    Testing on Your Steam Deck link

    Easy Setup link

    1. Run dragonruby-publish --only-package.
    2. Find the Linux build of your game under the ./builds directory and load it onto an SD Card.
    3. Restart the Steam Deck in Desktop Mode.
    4. Copy your game binary onto an SD card.
    5. Find the game on the SD card and double click binary.

    Advanced Setup link

    1. Restart the Steam Deck in Desktop Mode.
    2. Open up Konsole and set an admin password via passwd.
    3. Disable readonly mode: sudo steamos-readonly disable.
    4. Update pacman sudo pacman-key --populate archlinux.
    5. Update sshd_config sudo vim /etc/ssh/sshd_config and uncomment the PubkeyAuthentication yes line.
    6. Enable ssh: sudo systemctl enable sshd.
    7. Start ssh: sudo systemctl start sshd.
    8. Run dragonruby-publish --only-package.
    9. Use scp to copy the game over from your dev machine without needing an SD Card: scp -R ./builds/SOURCE.bin deck@IP_ADDRESS:/home/deck/Downloads

    Note: Steps 2 through 7 need only be done once.

    Note: scp comes pre-installed on Mac and Linux. You can download the tool for Windows from https://winscp.net/eng/index.php

    Setting up the game on the Partner Site link

    Getting your App ID link

    You'll need to create a product on Steam. This is unfortunately manual and requires identity verification for taxation purposes. Valve offers pretty robust documentation on all this, though. Eventually, you'll have an App ID for your game.

    Go to https://partner.steamgames.com/apps/view/$APPID, where $APPID is your game's App ID.

    Specifing Supported Operating Systems for your game link

    Find the "Supported Operating Systems" section and make sure these things are checked:

    Click the "Save" button below it.

    Setting up SteamPipe Depots link

    Click the "SteamPipe" tab at the top of the page, click on "depots"

    Click the "Add a new depot" button. Give it a name like "My Game Name Linux Depot" and take whatever depot ID it offers you.

    You'll see this new depot is listed on the page now. Fix its settings:

    Do this again, make a "My Game Name Windows Depot", set it to the same things, except "Operating System," which should be "Windows," of course.

    Do this again, make a "My Game Name Mac Depot", set it to the same things, except "Operating System," which should be "macOS," of course.

    Push the big green "Save" button on the page. Now we have a place to upload platform-specific builds of your game.

    Setting up Launch Options link

    Click on the "Installation" tab near the top of the page, then "General Installation".

    Under "Launch Options," click the "Add new launch option" button, edit the new section that just popped up, and set it like this:

    (Whenever you see "mygamename" in here, this should be whatever your game_metadata's "gameid" value is set to. If you see "My Game Name", it's whatever your game_metadata's "gametitle" value is set to, but you'll have to check in case we mangled it to work as a filename.)

    Click the "Update" button on that section.

    Add another launch option, as before:

    Add another launch option, as before:

    Publish Changes link

    Go to the "Publish" tab at near the top of the page. Click the "View Diffs" button and make sure it looks sane (it should just be the things we've changed in here), then click "Prepare for Publishing", then "Publish to Steam" and follow the instructions to publish these changes.

    Go to https://partner.steamgames.com/apps/associated/$APPID For each package, make sure all three depots are included.

    Configuring dragonruby-publish link

    You only have to do this part once when first setting up your game. Note that this capability is only available for Indie and Pro license tiers. If you have a Standard DragonRuby License, you'll need to use the Steamworks toolchains directly.

    Go add a text file to your game's metadata directory called steam_metadata.txt ... note that this file will be filtered out dragonruby-publish packages the game and will not be distributed with the published game. 

    steam.publish=true
steam.branch=public
steam.username=AAA
steam.appid=BBB
steam.linux_depotid=CCC
steam.windows_depotid=DDD
steam.mac_depotid=EEE

    If steam.publish is set to false then dragonruby-publish will not attempt to upload to Steam. false is the default if this file, or this setting, is missing.

    Where "AAA" is the login name on the Steamworks Partner Site to use for publishing builds, "BBB" is your game-specific AppID provided by Steam, "CCC", "DDD", and "EEE" are the DepotIDs you created for Linux, Windows, and macOS builds, respectively.

    Setting a branch live link

    Once your build is uploaded, you can assign it to a specific branch through the interface on the Partner site. You can make arbitrary branches here, like "beta" or "nightly" or "fixing-weird-bug" or whatever. The one that goes to the end users without them switching branches, is "default" and you should assume this is where paying customers live, so be careful before you set a build live there.

    You can have dragonruby-publish set the builds it publishes live on a branch immediately, if you prefer. Simply add... 

    steam.branch=XXX

    ...to steam_metadata.txt, where "XXX" is the branch name from the partner website. If this is blank or unspecified, it will _not_ set the build live on _any_ branch. Setting the value to public will push to production.

    A reasonable strategy is to create a (possibly passworded) branch called "staging" and have dragonruby-publish always push to there automatically. Then you can test from a Steam install, pushing as often as you like, and when you are satisfied, manually set the latest build live on default for the general public to download.

    If you are feeling brave, you can always just set all published builds live on default, too. After all, if you break it, you can always just push a fix right away. :) (or use the Partner Site to roll back to a known-good build, you know.)

    Publishing Build link

    Run dragonuby-publish as you normally would. When it is time to publish to Steam, it will set up any tools it needs, attempt to log you into Steam, and upload the latest version of your game.

    Steam login is handled by Valve's steamcmd command line program, not dragonruby-publish. DragonRuby does not ever have access to your login credentials. You may need to take steps to get an authorization token in place if necessary, so you don't have to deal with Steam Guard in automated build processes (documentation on how to do this is forthcoming, or read Valve's SteamCMD manual for details).

    You (currently) have to set the new build live on the partner site before users will receive it. Optionally automating this step is coming soon!

    Questions/Need Help? link

    You probably have several. Please come visit the Discord and ask questions, and we'll do our best to help, and update this document.

    DragonRuby's Philosophy link

    The following tenants of DragonRuby are what set us apart from other game engines. Given that Game Toolkit is a relatively new engine, there are definitely features that are missing. So having a big check list of "all the cool things" is not this engine's forte. This is compensated with a strong commitment to the following principles.

    Challenge The Status Quo link

    Game engines of today are in a local maximum and don't take into consideration the challenges of this day and age. Unity and GameMaker specifically rot your brain. It's not sufficient to say:

    But that's how we've always done it.

    It's a hard pill to swallow, but forget blindly accepted best practices and try to figure out the underlying motivation for a specific approach to game development. Collaborate with us.

    Continuity of Design link

    There is a programming idiom in software called "The Pit of Success". The term normalizes upfront pain as a necessity/requirement in the hopes that the investment will yield dividends "when you become successful" or "when the code becomes more complicated". This approach to development is strongly discouraged by us. It leads to over-architected and unnecessary code; creates barriers to rapid prototyping and shipping a game; and overwhelms beginners who are new to the engine or programming in general.

    DragonRuby's philosophy is to provide multiple options across the "make it fast" vs "make it right" spectrum, with incremental/intuitive transitions between the options provided. A concrete example of this philosophy would be render primitives: the spectrum of options allows renderable constructs that take the form of tuples/arrays (easy to pickup, simple, and fast to code/prototype with), hashes (a little more work, but gives you the ability to add additional properties), open and strict entities (more work than hashes, but yields cleaner apis), and finally - if you really need full power/flexibility in rendering - classes (which take the most amount of code and programming knowledge to create).

    Release Early and Often link

    The biggest mistake game devs make is spending too much time in isolation building their game. Release something, however small, and release it soon.

    Stop worrying about everything being pixel perfect. Don't wait until your game is 100% complete. Build your game publicly and iterate. Post in the #show-and-tell channel in the community Discord. You'll find a lot of support and encouragement there.

    Real artists ship. Remember that.

    Sustainable And Ethical Monetization link

    We all aspire to put food on the table doing what we love. Whether it is building games, writing tools to support game development, or anything in between.

    Charge a fair amount of money for the things you create. It's expected and encouraged within the community. Give what you create away for free to those that can't afford it.

    If you are gainfully employed, pay full price for the things you use. If you do end up getting something at a discount, pay the difference "forward" to someone else.

    Sustainable And Ethical Open Source link

    This goes hand in hand with sustainable and ethical monetization. The current state of open source is not sustainable. There is an immense amount of contributor burnout. Users of open source expect everything to be free, and few give back. This is a problem we want to fix (we're still trying to figure out the best solution).

    So, don't be "that guy" in the Discord that says "DragonRuby should be free and open source!" You will be personally flogged by Amir.

    People Over Entities link

    We prioritize the endorsement of real people over faceless entities. This game engine, and other products we create, are not insignificant line items of a large company. And you aren't a generic "commodity" or "corporate resource". So be active in the community Discord and you'll reap the benefits as more devs use DragonRuby.

    Building A Game Should Be Fun And Bring Happiness link

    We will prioritize the removal of pain. The aesthetics of Ruby make it such a joy to work with, and we want to capture that within the engine.

    Real World Application Drives Features link

    We are bombarded by marketing speak day in and day out. We don't do that here. There are things that are really great in the engine, and things that need a lot of work. Collaborate with us so we can help you reach your goals. Ask for features you actually need as opposed to anything speculative.

    We want DragonRuby to *actually* help you build the game you want to build (as opposed to sell you something piece of demoware that doesn't work).

    Frequently Asked Questions, Comments, and Concerns link

    Here are questions, comments, and concerns that frequently come up.

    Frequently Asked Questions link

    What is DragonRuby LLP? link

    DragonRuby LLP is a partnership of four devs who came together with the goal of bringing the aesthetics and joy of Ruby, everywhere possible.

    Under DragonRuby LLP, we offer a number of products (with more on the way):

    All of the products above leverage a shared core called DragonRuby.

    NOTE: From an official branding standpoint each one of the products is suffixed with "A DragonRuby LLP Product" tagline. Also, DragonRuby is _one word, title cased_.

    NOTE: We leave the "A DragonRuby LLP Product" off of this one because that just sounds really weird.

    NOTE: Devs who use DragonRuby are "Dragon Riders/Riders of Dragons". That's a bad ass identifier huh?

    What is DragonRuby? link

    The response to this question requires a few subparts. First we need to clarify some terms. Specifically _language specification_ vs _runtime_.

    Okay... so what is the difference between a language specification and a runtime?

    A runtime is an _implementation_ of a language specification. When people say "Ruby," they are usually referring to "the Ruby 3.0+ language specification implemented via the CRuby/MRI Runtime."

    But, there are many Ruby Runtimes: CRuby/MRI, JRuby, Truffle, Rubinius, Artichoke, and (last but certainly not least) DragonRuby.

    Okay... what language specification does DragonRuby use then?

    DragonRuby's goal is to be compliant with the ISO/IEC 30170:2012 standard. It's syntax is Ruby 2.x compatible, but also contains semantic changes that help it natively interface with platform specific libraries.

    So... why another runtime?

    The elevator pitch is:

    DragonRuby is a Multilevel Cross-platform Runtime. The "multiple levels" within the runtime allows us to target platforms no other Ruby can target: PC, Mac, Linux, Raspberry Pi, WASM, iOS, Android, Nintendo Switch, PS4, Xbox, and Stadia.

    What does Multilevel Cross-platform mean?

    There are complexities associated with targeting all the platforms we support. Because of this, the runtime had to be architected in such a way that new platforms could be easily added (which lead to us partitioning the runtime internally):

    Levels 1 through 3 are fairly commonplace in many runtime implementations (with level 1 being the most portable, and level 3 being the fastest). But the DragonRuby Runtime has taken things a bit further:

    These levels allow us to stay up to date with open source implementations of Ruby; provide fast, native code execution on proprietary platforms; ensure good separation between these two worlds; and provides a means to add new platforms without going insane.

    Cool cool. So given that I understand everything to this point, can we answer the original question? What is DragonRuby?

    DragonRuby is a Ruby runtime implementation that takes all the lessons we've learned from MRI/CRuby, and merges it with the latest and greatest compiler and OSS technologies.

    How is DragonRuby different than MRI? link

    DragonRuby supports a subset of MRI apis. Our target is to support all of mRuby's standard lib. There are challenges to this given the number of platforms we are trying to support (specifically console).

    Does DragonRuby support Gems?

    DragonRuby does not support gems because that requires the installation of MRI Ruby on the developer's machine (which is a non-starter given that we want DragonRuby to be a zero dependency runtime). While this seems easy for Mac and Linux, it is much harder on Windows and Raspberry Pi. mRuby has taken the approach of having a git repository for compatible gems and we will most likely follow suite: https://github.com/mruby/mgem-list.

    Does DragonRuby have a REPL/IRB?

    You can use DragonRuby's Console within the game to inspect object and execute small pieces of code. For more complex pieces of code create a file called repl.rb and put it in mygame/app/repl.rb: 

    repl do
  puts "hello world"
  puts 1 + 1
end

    4. To ignore code in repl.rb, instead of commenting it out, prefix repl with the letter x and it'll be ignored. 

    xrepl do # <------- line is prefixed with an "x"
  puts "hello world"
  puts 1 + 1
end

# This code will be executed when you save the file.
repl do
  puts "Hello"
end

repl do
  puts "This code will also be executed."
end

# use xrepl to "comment out" code
xrepl do
  puts "This code will not be executed because of the x in front of repl".
end

    Does DragonRuby support pry or have any other debugging facilities?

    pry is a gem that assumes you are using the MRI Runtime (which is incompatible with DragonRuby). Eventually DragonRuby will have a pry based experience that is compatible with a debugging infrastructure called LLDB. Take the time to read about LLDB as it shows the challenges in creating something that is compatible.

    You can use DragonRuby's replay capabilities to troubleshoot:

    1. DragonRuby is hot loaded which gives you a very fast feedback loop (if the game throws an exception, it's because of the code you just added).
    2. Use ./dragonruby mygame --record to create a game play recording that you can use to find the exception (you can replay a recording by executing ./dragonruby mygame --replay last_replay.txt or through the DragonRuby Console using $gtk.recording.start_replay "last_replay.txt".
    3. DragonRuby also ships with a unit testing facility. You can invoke the following command to run a test: ./dragonruby mygame --test tests/some_ruby_file.rb.
    4. Get into the habit of adding debugging facilities within the game itself. You can add drawing primitives to args.outputs.debug that will render on top of your game but will be ignored in a production release.
    5. Debugging something that runs at 60fps is (imo) not that helpful. The exception you are seeing could have been because of a change that occurred many frames ago.

    Frequent Comments About Ruby as a Language Choice link

    But Ruby is dead. link

    Let's check the official source for the answer to this question: isrubydead.com: https://isrubydead.com/.

    On a more serious note, Ruby's _quantity_ levels aren't what they used to be. And that's totally fine. Everyone chases the new and shiny.

    What really matters is _quality/maturity_. Here's a StackOverflow Survey sorted by highest paid developers: https://insights.stackoverflow.com/survey/2021#section-top-paying-technologies-top-paying-technologies.

    Let's stop making this comment shall we?

    But Ruby is slow. link

    That doesn't make any sense. A language specification can't be slow... it's a language spec. Sure, an _implementation/runtime_ can be slow though, but then we'd have to talk about which runtime.

    Here's a some quick demonstrations of how well DragonRuby Game Toolkit Performs:

    Dynamic languages are slow. link

    They are certainly slower than statically compiled languages. With the processing power and compiler optimizations we have today, dynamic languages like Ruby are _fast enough_.

    Unless you are writing in some form of intermediate representation by hand, your language of choice also suffers this same fallacy of slow. Like, nothing is faster than a low level assembly-like language. So unless you're writing in that, let's stop making this comment.

    NOTE: If you _are_ hand writing LLVM IR, we are always open to bringing on new partners with such a skill set. Email us ^_^.

    Frequent Concerns link

    DragonRuby is not open source. That's not right. link

    The current state of open source is unsustainable. Contributors work for free, most all open source repositories are severely under-staffed, and burnout from core members is rampant.

    We believe in open source very strongly. Parts of DragonRuby are in fact, open source. Just not all of it (for legal reasons, and because the IP we've created has value). And we promise that we are looking for (or creating) ways to _sustainably_ open source everything we do.

    If you have ideas on how we can do this, email us!

    If the reason above isn't sufficient, then definitely use something else.

    All this being said, we do have parts of the engine open sourced on GitHub: https://github.com/dragonruby/dragonruby-game-toolkit-contrib/

    DragonRuby is for pay. You should offer a free version. link

    If you can afford to pay for DragonRuby, you should (and will). We don't tell authors that they should give us their books for free, and only require payment if we read the entire thing. It's time we stop asking that of software products.

    That being said, we will _never_ put someone out financially. We have income assistance for anyone that can't afford a license to any one of our products.

    You qualify for a free, unrestricted license to DragonRuby products if any of the following items pertain to you:

    Just contact Amir at [email protected] with a short explanation of your current situation and he'll set you up. No questions asked.

    But still, you should offer a free version. So I can try it out and see if I like it. link

    You can try our web-based sandbox environment at http://fiddle.dragonruby.org. But it won't do the runtime justice. Or just come to our Discord Channel at http://discord.dragonruby.org and ask questions. We'd be happy to have a one on one video chat with you and show off all the cool stuff we're doing.

    Seriously just buy it. Get a refund if you don't like it. We make it stupid easy to do so.

    I still think you should do a free version. Think of all people who would give it a shot. link

    Free isn't a sustainable financial model. We don't want to spam your email. We don't want to collect usage data off of you either. We just want to provide quality toolchains to quality developers (as opposed to a large quantity of developers).

    The people that pay for DragonRuby and make an effort to understand it are the ones we want to build a community around, partner with, and collaborate with. So having that small monetary wall deters entitled individuals that don't value the same things we do.

    What if I build something with DragonRuby, but DragonRuby LLP becomes insolvent. link

    We want to be able to work on the stuff we love, every day of our lives. And we'll go to great lengths to make that continues.

    But, in the event that sad day comes, our partnership bylaws state that _all_ DragonRuby IP that can be legally open sourced, will be released under a permissive license.

    RECIPIES: link

    How To Determine What Frame You Are On link

    There is a property on state called tick_count that is incremented by DragonRuby every time the tick method is called. The following code renders a label that displays the current tick_count. 

    def tick args
  args.outputs.labels << [10, 670, "#{args.state.tick_count}"]
end

    How To Get Current Framerate link

    Current framerate is a top level property on the Game Toolkit Runtime and is accessible via args.gtk.current_framerate. 

    def tick args
  args.outputs.labels << [10, 710, "framerate: #{args.gtk.current_framerate.round}"]
end

    How To Render A Sprite Using An Array link

    All file paths should use the forward slash / *not* backslash . Game Toolkit includes a number of sprites in the sprites folder (everything about your game is located in the mygame directory).

    The following code renders a sprite with a width and height of 100 in the center of the screen.

    args.outputs.sprites is used to render a sprite.

    NOTE: Rendering using an Array is "quick and dirty". It's generally recommended that you render using Hashes long term. 

    def tick args
  args.outputs.sprites << [
    640 - 50,                 # X
    360 - 50,                 # Y
    100,                      # W
    100,                      # H
    'sprites/square-blue.png' # PATH
 ]
end

    Rendering a Sprite Using a Hash link

    Using ordinal positioning can get a little unruly given so many properties you have control over.

    You can represent a sprite as a Hash: 

    def tick args
  args.outputs.sprites << {
    x: 640 - 50,
    y: 360 - 50,
    w: 100,
    h: 100,

    path: 'sprites/square-blue.png',
    angle: 0,

    a: 255,
    r: 255,
    g: 255,
    b: 255,

    # source_ properties have origin of bottom left
    source_x:  0,
    source_y:  0,
    source_w: -1,
    source_h: -1,

    # tile_ properties have origin of top left
    tile_x:  0,
    tile_y:  0,
    tile_w: -1,
    tile_h: -1,

    flip_vertically: false,
    flip_horizontally: false,

    angle_anchor_x: 0.5,
    angle_anchor_y: 1.0,

    blendmode_enum: 1

    # sprites anchor/alignment (default is nil)
    anchor_x: 0.5,
    anchor_y: 0.5
  }
end

    The blendmode_enum value can be set to 0 (no blending), 1 (alpha blending), 2 (additive blending), 3 (modulo blending), 4 (multiply blending).

    How To Render A Label link

    args.outputs.labels is used to render labels.

    Labels are how you display text. This code will go directly inside of the def tick args method.

    NOTE: Rendering using an Array is "quick and dirty". It's generally recommended that you render using Hashes long term.

    Here is the minimum code: 

    def tick args
  #                       X    Y    TEXT
  args.outputs.labels << [640, 360, "I am a black label."]
end

    A Colored Label link

    def tick args
  # A colored label
  #                       X    Y    TEXT,                   RED    GREEN  BLUE  ALPHA
  args.outputs.labels << [640, 360, "I am a redish label.", 255,     128,  128,   255]
end

    Extended Label Properties link

    def tick args
  # A colored label
  #                       X    Y     TEXT           SIZE  ALIGNMENT  RED  GREEN  BLUE  ALPHA  FONT FILE
  args.outputs.labels << [
    640,                   # X
    360,                   # Y
    "Hello world",         # TEXT
    0,                     # SIZE_ENUM
    1,                     # ALIGNMENT_ENUM
    0,                     # RED
    0,                     # GREEN
    0,                     # BLUE
    255,                   # ALPHA
    "fonts/coolfont.ttf"   # FONT
  ]
end

    A SIZE_ENUM of 0 represents "default size". A negative value will decrease the label size. A positive value will increase the label's size.

    An ALIGNMENT_ENUM of 0 represents "left aligned". 1 represents "center aligned". 2 represents "right aligned".

    Rendering A Label As A Hash link

    You can add additional metadata about your game within a label, which requires you to use a `Hash` instead.

    If you use a Hash to render a label, you can set the label's size using either SIZE_ENUM or SIZE_PX. If both options are provided, SIZE_PX will be used. 

    def tick args
  args.outputs.labels << {
    x:                       200,
    y:                       550,
    text:                    "dragonruby",
    # size specification can be either size_enum or size_px
    size_enum:               2,
    size_px:                 22,
    alignment_enum:          1,
    r:                       155,
    g:                       50,
    b:                       50,
    a:                       255,
    font:                    "fonts/manaspc.ttf",
    vertical_alignment_enum: 0, # 0 is bottom, 1 is middle, 2 is top
    anchor_x: 0.5,
    anchor_y: 0.5
    # You can add any properties you like (this will be ignored/won't cause errors)
    game_data_one:  "Something",
    game_data_two: {
       value_1: "value",
       value_2: "value two",
       a_number: 15
    }
  }
end

    Getting The Size Of A Piece Of Text link

    You can get the render size of any string using args.gtk.calcstringbox. 

    def tick args
  #                             TEXT           SIZE_ENUM  FONT
  w, h = args.gtk.calcstringbox("some string",         0, "font.ttf")

  # NOTE: The SIZE_ENUM and FONT are optional arguments.

  # Render a label showing the w and h of the text:
  args.outputs.labels << [
    10,
    710,
    # This string uses Ruby's string interpolation literal: #{}
    "'some string' has width: #{w}, and height: #{h}."
  ]
end

    Rendering Labels With New Line Characters And Wrapping link

    You can use a strategy like the following to create multiple labels from a String. 

    def tick args
  long_string = "Lorem ipsum dolor sit amet, consectetur adipiscing elitteger dolor velit, ultricies vitae libero vel, aliquam imperdiet enim."
  max_character_length = 30
  long_strings_split = args.string.wrapped_lines long_string, max_character_length
  args.outputs.labels << long_strings_split.map_with_index do |s, i|
    { x: 10, y: 600 - (i * 20), text: s }
  end
end

    How To Play A Sound link

    Sounds that end .wav will play once: 

    def tick args
  # Play a sound every second
  if (args.state.tick_count % 60) == 0
    args.outputs.sounds << 'something.wav'
  end
end

    Sounds that end .ogg is considered background music and will loop: 

    def tick args
  # Start a sound loop at the beginning of the game
  if args.state.tick_count == 0
    args.outputs.sounds << 'background_music.ogg'
  end
end

    If you want to play a .ogg once as if it were a sound effect, you can do: 

    def tick args
  # Play a sound every second
  if (args.state.tick_count % 60) == 0
    args.gtk.queue_sound 'some-ogg.ogg'
  end
end

    Using args.state To Store Your Game State link

    args.state is a open data structure that allows you to define properties that are arbitrarily nested. You don't need to define any kind of class.

    To initialize your game state, use the ||= operator. Any value on the right side of ||= will only be assigned _once_.

    To assign a value every frame, just use the = operator, but _make sure_ you've initialized a default value. 

    def tick args
  # initialize your game state ONCE
  args.state.player.x  ||= 0
  args.state.player.y  ||= 0
  args.state.player.hp ||= 100

  # increment the x position of the character by one every frame
  args.state.player.x += 1

  # Render a sprite with a label above the sprite
  args.outputs.sprites << [
    args.state.player.x,
    args.state.player.y,
    32, 32,
    "player.png"
  ]

  args.outputs.labels << [
    args.state.player.x,
    args.state.player.y - 50,
    args.state.player.hp
  ]
end

    Accessing files link

    DragonRuby uses a sandboxed filesystem which will automatically read from and write to a location appropriate for your platform so you don't have to worry about theses details in your code. You can just use gtk.read_file, gtk.write_file, and gtk.append_file with a relative path and the engine will take care of the rest.

    The data directories that will be written to in a production build are:

    The values in square brackets are the values you set in your app/metadata/game_metadata.txt file.

    When reading files, the engine will first look in the game's data directory and then in the game directory itself. This means that if you write a file to the data directory that already exists in your game directory, the file in the data directory will be used instead of the one that is in your game.

    When running a development build you will directly write to your game directory (and thus overwrite existing files). This can be useful for built-in development tools like level editors.

    For more details on the implementation of the sandboxed filesystem, see Ryan C. Gordon's PhysicsFS documentation: https://icculus.org/physfs/

    IMPORTANT: File access functions are sandoxed and assume that the dragonruby binary lives alongside the game you are building. Do not expect file access functions to return correct values if you are attempting to run the dragonruby binary from a shared location. It's recommended that the directory structure contained in the zip is not altered and games are built using that starter template.

    Troubleshoot Performance link

    args.state.bullets.each do |bullet|
  args.outputs.sprites << bullet.sprite
end

    do 

    args.outputs.sprites << args.state.bullets.map do |b|
  b.sprite
end

    args.state.fx_queue |fx|
  fx.count_down ||= 255
  fx.countdown -= 5
  if fx.countdown < 0
    args.state.fx_queue.delete fx
  end
end

    Do: 

    args.state.fx_queue |fx|
  fx.count_down ||= 255
  fx.countdown -= 5
end

args.state.fx_queue.reject! { |fx| fx.countdown < 0 }

    Outputs (args.outputs) link

    Outputs is how you render primitives to the screen. The minimal setup for rendering something to the screen is via a tick method defined in mygame/app/main.rb 

    def tick args
  args.outputs.solids     << { x: 0, y: 0, w: 100, h: 100 }
  args.outputs.sprites    << { x: 100, y: 100, w: 100, h: 100, path: "sprites/square/blue.png" }
  args.outputs.labels     << { x: 200, y: 200, text: "Hello World" }
  args.outputs.borders    << { x: 0, y: 0, w: 100, h: 100 }
  args.outputs.lines      << { x: 300, y: 300, x2: 400, y2: 400 }
end

    Collection Render Orders link

    Primitives are rendered first-in, first-out. The rendering order (sorted by bottom-most to top-most):

    Primitives Collection (args.outputs.primitives) link

    args.outputs.primitives can take in any primitive and will render first in, first out.

    For example, you can render a solid above a sprite: 

    def tick args
  args.outputs.primitives << { x: 100, y: 100,
                               w: 100, h: 100,
                               path: "sprites/square/blue.png" }
  args.outputs.primitives << { x: 0, y: 0, w: 100, h: 100, primitive_marker: :solid }
  args.outputs.primitives << { x: 0, y: 0, w: 100, h: 100, primitive_marker: :border }
end

    Debug Collection (args.outputs.debug) link

    args.outputs.debug will not render in production mode and behaves like args.outputs.primitives. Objects in this collection are rendered above everything.

    Additionally, args.outputs.debug allows you to pass in a String as a primitive type. This is helpful for quickly showing the value of a variable on the screen. A label with black text and a white background will be created for each String sent in. The labels will be automatically stacked vertically for you.

    Example: 

    def tick args
  args.state.player ||= { x: 100, y: 100 }
  args.state.player.x += 1
  args.state.player.x = 0 if args.state.player.x > 1280

  # the following string values will generate labels with backgrounds
  # and will auto stack vertically
  args.outputs.debug << "current tick: #{args.state.tick_count}"
  args.outputs.debug << "player x: #{args.state.player.x}"
end

    solids link

    Add primitives to this collection to render a solid to the screen.

    Rendering a solid using an Array link

    Creates a solid black rectangle located at 100, 100. 160 pixels wide and 90 pixels tall. 

    def tick args
  #                         X    Y  WIDTH  HEIGHT
  args.outputs.solids << [100, 100,   160,     90]
end

    Rendering a solid using an Array with colors and alpha link

    The value for the color and alpha is a number between 0 and 255. The alpha property is optional and will be set to 255 if not specified.

    Creates a green solid rectangle with an opacity of 50%. 

    def tick args
  #                         X    Y  WIDTH  HEIGHT  RED  GREEN  BLUE  ALPHA
  args.outputs.solids << [100, 100,   160,     90,   0,   255,    0,   128]
end

    Rendering a solid using a Hash link

    If you want a more readable invocation. You can use the following hash to create a solid. Any parameters that are not specified will be given a default value. The keys of the hash can be provided in any order. 

    def tick args
  args.outputs.solids << {
    x:    0,
    y:    0,
    w:  100,
    h:  100,
    r:    0,
    g:  255,
    b:    0,
    a:  255,
    anchor_x: 0,
    anchor_y: 0,
    blendmode_enum: 1
  }
end

    Rendering a solid using a Class link

    You can also create a class with solid properties and render it as a primitive. ALL properties must be on the class. *Additionally*, a method called primitive_marker must be defined on the class.

    Here is an example: 

    # Create type with ALL solid properties AND primitive_marker
class Solid
  attr_accessor :x, :y, :w, :h, :r, :g, :b, :a, :anchor_x, :anchor_y, :blendmode_enum

  def primitive_marker
    :solid # or :border
  end
end

# Inherit from type
class Square < Solid
  # constructor
  def initialize x, y, size
    self.x = x
    self.y = y
    self.w = size
    self.h = size
  end
end

def tick args
  # render solid/border
  args.outputs.solids  << Square.new(10, 10, 32)
end

    borders link

    Add primitives to this collection to render an unfilled solid to the screen. Take a look at the documentation for Outputs#solids.

    The only difference between the two primitives is where they are added.

    Instead of using args.outputs.solids: 

    def tick args
  #                         X    Y  WIDTH  HEIGHT
  args.outputs.solids << [100, 100,   160,     90]
end

    You have to use args.outputs.borders: 

    def tick args
  #                           X    Y  WIDTH  HEIGHT
  args.outputs.borders << [100, 100,   160,     90]
end

    sprites link

    Add primitives to this collection to render a sprite to the screen.

    Rendering a sprite using an Array link

    Creates a sprite of a white circle located at 100, 100. 160 pixels wide and 90 pixels tall. 

    def tick args
  #                         X    Y   WIDTH   HEIGHT                      PATH
  args.outputs.sprites << [100, 100,   160,     90, "sprites/circle/white.png"]
end

    Rendering a sprite using a Hash link

    If you want a more readable (and faster) invocation, you can use the following hash to create a sprite. Any parameters that are not specified will be given a default value. The keys of the hash can be provided in any order. 

    def tick args
  args.outputs.sprites << {
    x:                             0,
    y:                             0,
    w:                           100,
    h:                           100,
    path: "sprites/circle/white.png",
    angle:                         0,
    a:                           255,
    r:                             0,
    g:                           255,
    b:                             0
  }
end

    Here are all the properties that you can set on a sprite. The only required ones are x, y, w, h, and path.

    Required properties

    Anchors and Rotations

    Here's an example of rendering a 80x80 pixel sprite in the center of the screen: 

    def tick args
  args.outputs.sprites << {
    x: 640 - 40, # the logical center of the screen horizontally is 640, minus half the width of the sprite
    y: 360 - 40, # the logical center of the screen vertically is 360, minus half the height of the sprite
    w: 80,
    h: 80,
    path: "sprites/square/blue.png"
 }
end

    Instead of computing the offset, you can use anchor_x, and anchor_y to center the sprite. The following is equivalent to the code above: 

    def tick args
  args.outputs.sprites << {
    x: 640,
    y: 360,
    w: 80,
    h: 80,
    path: "sprites/square/blue.png",
    anchor_x: 0.5, # position horizontally at 0.5 of the sprite's width
    anchor_y: 0.5  # position vertically at 0.5 of the sprite's height
 }
end

    Cropping Properties

    See the sample apps under ./samples/03_rendering_sprites for examples of how to use this properties non-trivially.

    Blending Options

    The following sample apps show how blendmode_enum can be leveraged to create coloring and lighting effects:

    Triagles (Indie, Pro Feature)

    Sprites can be rendered as triangles at the Indie and Pro License Tiers. To rendering using triangles, instead of providing a w, h property, provide x2, y2, x3, y3. This applies for positioning and cropping.

    Here is an example: 

    def tick args
  args.outputs.sprites << {
    x: 0,
    y: 0,
    x2: 80,
    y2: 0,
    x3: 0,
    y3: 80,
    source_x: 0,
    source_y: 0,
    source_x2: 80,
    source_y2: 0,
    source_x3: 0,
    source_y3: 80,
    path: "sprites/square/blue.png"
  }
end

    For more example of rendering using triangles see:

    Rendering a sprite using a Class link

    You can also create a class with solid/border properties and render it as a primitive. ALL properties must be on the class. *Additionally*, a method called primitive_marker must be defined on the class.

    Here is an example: 

    # Create type with ALL sprite properties AND primitive_marker
class Sprite
  attr_accessor :x, :y, :w, :h, :path, :angle, :a, :r, :g, :b, :tile_x,
                :tile_y, :tile_w, :tile_h, :flip_horizontally,
                :flip_vertically, :angle_anchor_x, :angle_anchor_y, :id,
                :angle_x, :angle_y, :z,
                :source_x, :source_y, :source_w, :source_h, :blendmode_enum,
                :source_x2, :source_y2, :source_x3, :source_y3, :x2, :y2, :x3, :y3,
                :anchor_x, :anchor_y

  def primitive_marker
    :sprite
  end
end

# Inherit from type
class Circle < Sprite
  # constructor
  def initialize x, y, size, path
    self.x = x
    self.y = y
    self.w = size
    self.h = size
    self.path = path
  end

  def serialize
    {x:self.x, y:self.y, w:self.w, h:self.h, path:self.path}
  end

  def inspect
    serialize.to_s
  end

  def to_s
    serialize.to_s
  end
end

def tick args
  # render circle sprite
  args.outputs.sprites  << Circle.new(10, 10, 32,"sprites/circle/white.png")
end

    attr_sprite link

    The attr_sprite class macro adds all properties needed to render a sprite to a class. This removes the need to manually define all sprites properties that DragonRuby offers for rendering.

    Instead of manually defining the properties, you can represent a sprite using the attr_sprite class macro: 

    class BlueSquare
  # invoke the helper function at the class level for
  # anything you want to represent as a sprite
  attr_sprite

  def initialize(x: 0, y: 0, w: 0, h: 0k
    @x = x
    @y = y
    @w = w
    @h = h
    @path = 'sprites/square-blue.png'
  end
end

def tick args
  args.outputs.sprites << BlueSquare.new(x: 640 - 50,
                                         y: 360 - 50,
                                         w: 50,
                                         h: 50)
end

    labels link

    Add primitives to this collection to render a label.

    Rendering a label using an Array link

    Labels represented as Arrays/Tuples: 

    def tick args
                         #        X         Y              TEXT   SIZE_ENUM
  args.outputs.labels << [175 + 150, 610 - 50, "Smaller label.",         0]
end

    Here are all the properties that you can set with a label represented as an Array. It's recommended to move over to using Hashes once you've specified a lot of properties. 

    def tick args
  args.outputs.labels << [
    640,                   # X
    360,                   # Y
    "Hello world",         # TEXT
    0,                     # SIZE_ENUM
    1,                     # ALIGNMENT_ENUM
    0,                     # RED
    0,                     # GREEN
    0,                     # BLUE
    255,                   # ALPHA
    "fonts/coolfont.ttf"   # FONT
  ]
end
d

    Rendering a label using a Hash link

    def tick args
  args.outputs.labels << {
      x:                       200,
      y:                       550,
      text:                    "dragonruby",
      size_enum:               2,
      alignment_enum:          1, # 0 = left, 1 = center, 2 = right
      r:                       155,
      g:                       50,
      b:                       50,
      a:                       255,
      font:                    "fonts/manaspc.ttf",
      vertical_alignment_enum: 0  # 0 = bottom, 1 = center, 2 = top
  }
end

    Screenshots link

    Add a hash to this collection to take a screenshot and save as png file. The keys of the hash can be provided in any order. 

    def tick args
  args.outputs.screenshots << {
    x: 0, y: 0, w: 100, h: 100,    # Which portion of the screen should be captured
    path: 'screenshot.png',        # Output path of PNG file (inside game directory)
    r: 255, g: 255, b: 255, a: 0   # Optional chroma key
  }
end

    Chroma key (Making a color transparent) link

    By specifying the r, g, b and a keys of the hash you change the transparency of a color in the resulting PNG file. This can be useful if you want to create files with transparent background like spritesheets. The transparency of the color specified by r, g, b will be set to the transparency specified by a.

    The example above sets the color white (255, 255, 255) as transparent.

    Inputs (args.inputs) link

    Access using input using args.inputs.

    last_active link

    This function returns the last active input which will be set to either :keyboard, :mouse, or :controller. The function is helpful when you need to present on screen instructions based on the input the player chose to play with. 

    def tick args
  if args.inputs.last_active == :controller
    args.outputs.labels << { x: 60, y: 60, text: "Use the D-Pad to move around." }
  else
    args.outputs.labels << { x: 60, y: 60, text: "Use the arrow keys to move around." }
  end
end

    :mouse, or :controller. The function is helpful when you need to present on screen instructions based on the input the player chose to play with.

    locale link

    Returns the ISO 639-1 two-letter langauge code based on OS preferences. Refer to the following link for locale strings: https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes).

    Defaults to "en" if locale can't be retrieved (args.inputs.locale_raw will be nil in this case).

    up link

    Returns true if: the up arrow or w key is pressed or held on the keyboard; or if up is pressed or held on controller_one; or if the left_analog on controller_one is tilted upwards.

    down link

    Returns true if: the down arrow or s key is pressed or held on the keyboard; or if down is pressed or held on controller_one; or if the left_analog on controller_one is tilted downwards.

    left link

    Returns true if: the left arrow or a key is pressed or held on the keyboard; or if left is pressed or held on controller_one; or if the left_analog on controller_one is tilted to the left.

    right link

    Returns true if: the right arrow or d key is pressed or held on the keyboard; or if right is pressed or held on controller_one; or if the left_analog on controller_one is tilted to the right.

    left_right link

    Returns -1 (left), 0 (neutral), or +1 (right). This method is aliased to args.inputs.left_right_with_wasd.

    The following inputs are inspected to determine the result:

    left_right_perc link

    Returns a floating point value between -1 and 1. This method is aliased to args.inputs.left_right_perc_with_wasd

    The following inputs are inspected to dermine the result:

    left_right_directional link

    Returns -1 (left), 0 (neutral), or +1 (right). This method is aliased to args.inputs.left_right_arrow.

    The following inputs are inspected to determine the result:

    left_right_directional_perc link

    Returns a floating point value between -1 and 1. The following inputs are inspected to dermine the result:

    Here is some sample code to help visualize the left_right functions. 

    def tick args
  args.outputs.debug << "* Variations of args.inputs.left_right"
  args.outputs.debug << "  args.inputs.left_right(_with_wasd) #{args.inputs.left_right}"
  args.outputs.debug << "  args.inputs.left_right_perc(_with_wasd) #{args.inputs.left_right_perc}"
  args.outputs.debug << "  args.inputs.left_right_directional #{args.inputs.left_right_directional}"
  args.outputs.debug << "  args.inputs.left_right_directional_perc #{args.inputs.left_right_directional_perc}"
  args.outputs.debug << "** Keyboard"
  args.outputs.debug << "   args.inputs.keyboard.a #{args.inputs.keyboard.a}"
  args.outputs.debug << "   args.inputs.keyboard.d #{args.inputs.keyboard.d}"
  args.outputs.debug << "   args.inputs.keyboard.left_arrow #{args.inputs.keyboard.left_arrow}"
  args.outputs.debug << "   args.inputs.keyboard.right_arrow #{args.inputs.keyboard.right_arrow}"
  args.outputs.debug << "** Controller"
  args.outputs.debug << "   args.inputs.controller_one.dpad_left #{args.inputs.controller_one.dpad_left}"
  args.outputs.debug << "   args.inputs.controller_one.dpad_right #{args.inputs.controller_one.dpad_right}"
  args.outputs.debug << "   args.inputs.controller_one.left_analog_x_perc #{args.inputs.controller_one.left_analog_x_perc}"
end

    up_down link

    Returns -1 (down), 0 (neutral), or +1 (up). This method is aliased to args.inputs.up_down_with_wasd.

    The following inputs are inspected to determine the result:

    up_down_directional link

    Returns -1 (down), 0 (neutral), or +1 (up). This method is aliased to args.inputs.up_down_arrow.

    The following inputs are inspected to determine the result:

    up_down_perc link

    Returns a floating point value between -1 and 1. The following inputs are inspected to dermine the result:

    Here is some sample code to help visualize the up_down functions. 

    def tick args
  args.outputs.debug << "* Variations of args.inputs.up_down"
  args.outputs.debug << "  args.inputs.up_down #{args.inputs.up_down}"
  args.outputs.debug << "  args.inputs.up_down_directional #{args.inputs.up_down_directional}"
  args.outputs.debug << "  args.inputs.up_down_perc #{args.inputs.up_down_perc}"
  args.outputs.debug << "** Keyboard"
  args.outputs.debug << "   args.inputs.keyboard.a #{args.inputs.keyboard.a}"
  args.outputs.debug << "   args.inputs.keyboard.d #{args.inputs.keyboard.d}"
  args.outputs.debug << "   args.inputs.keyboard.up_arrow #{args.inputs.keyboard.up_arrow}"
  args.outputs.debug << "   args.inputs.keyboard.down_arrow #{args.inputs.keyboard.down_arrow}"
  args.outputs.debug << "** Controller"
  args.outputs.debug << "   args.inputs.controller_one.dpad_up #{args.inputs.controller_one.dpad_up}"
  args.outputs.debug << "   args.inputs.controller_one.dpad_down #{args.inputs.controller_one.dpad_down}"
  args.outputs.debug << "   args.inputs.controller_one.up_analog_x_perc #{args.inputs.controller_one.up_analog_x_perc}"
end

    text link

    Returns a string that represents the last key that was pressed on the keyboard.

    Mouse (args.inputs.mouse) link

    Represents the user's mouse.

    has_focus link

    Return's true if the game has mouse focus.

    x link

    Returns the current x location of the mouse.

    y link

    Returns the current y location of the mouse.

    inside_rect? rect link

    Return. args.inputs.mouse.inside_rect? takes in any primitive that responds to x, y, w, h:

    inside_circle? center_point, radius link

    Returns true if the mouse is inside of a specified circle. args.inputs.mouse.inside_circle? takes in any primitive that responds to x, y (which represents the circle's center), and takes in a radius:

    moved link

    Returns true if the mouse has moved on the current frame.

    button_left link

    Returns true if the left mouse button is down.

    button_middle link

    Returns true if the middle mouse button is down.

    button_right link

    Returns true if the right mouse button is down.

    button_bits link

    Returns a bitmask for all buttons on the mouse: 1 for a button in the down state, 0 for a button in the up state.

    wheel link

    Represents the mouse wheel. Returns nil if no mouse wheel actions occurred. Otherwise args.inputs.mouse.wheel will return a Hash with x, and y (representing movement on each axis).

    click OR down, previous_click, up link

    The properties args.inputs.mouse.(click|down|previous_click|up) each return nil if the mouse button event didn't occur. And return an Entity that has an x, y properties along with helper functions to determine collision: inside_rect?, inside_circle. This value will be true if any of the mouse's buttons caused these events. To scope to a specific button use .button_left, .button_middle, .button_right, or .button_bits.

    Touch link

    The following touch apis are available on touch devices (iOS, Android, Mobile Web, Surface).

    args.inputs.touch link

    Returns a Hash representing all touch points on a touch device.

    args.inputs.finger_left link

    Returns a Hash with x and y denoting a touch point that is on the left side of the screen.

    args.inputs.finger_right link

    Returns a Hash with x and y denoting a touch point that is on the right side of the screen.

    Controller (args.inputs.controller_(one-four)) link

    Represents controllers connected to the usb ports.

    active link

    Returns true if any of the controller's buttons were used.

    up link

    Returns true if up is pressed or held on the directional or left analog.

    down link

    Returns true if down is pressed or held on the directional or left analog.

    left link

    Returns true if left is pressed or held on the directional or left analog.

    right link

    Returns true if right is pressed or held on the directional or left analog.

    left_right link

    Returns -1 (left), 0 (neutral), or +1 (right) depending on results of args.inputs.controller_(one-four).left and args.inputs.controller_(one-four).right.

    up_down link

    Returns -1 (down), 0 (neutral), or +1 (up) depending on results of args.inputs.controller_(one-four).up and args.inputs.controller_(one-four).down.

    (left|right)_analog_x_raw link

    Returns the raw integer value for the analog's horizontal movement (-32,767 to +32,767).

    (left|right)_analog_y_raw link

    Returns the raw integer value for the analog's vertical movement (-32,767 to +32,767).

    (left|right)_analog_x_perc link

    Returns a number between -1 and 1 which represents the percentage the analog is moved horizontally as a ratio of the maximum horizontal movement.

    (left|right)_analog_y_perc link

    Returns a number between -1 and 1 which represents the percentage the analog is moved vertically as a ratio of the maximum vertical movement.

    dpad_up, directional_up link

    Returns true if up is pressed or held on the dpad.

    dpad_down, directional_down link

    Returns true if down is pressed or held on the dpad.

    dpad_left, directional_left link

    Returns true if left is pressed or held on the dpad.

    dpad_right, directional_right link

    Returns true if right is pressed or held on the dpad.

    (a|b|x|y|l1|r1|l2|r2|l3|r3|start|select) link

    Returns true if the specific button is pressed or held. Note: For PS4 and PS5 controllers a maps to Cross, b maps to Circle, x maps to Square, and y maps to Triangle.

    truthy_keys link

    Returns a collection of Symbols that represent all keys that are in the pressed or held state.

    key_down link

    Returns true if the specific button was pressed on this frame. args.inputs.controller_(one-four).key_down.BUTTON will only be true on the frame it was pressed.

    key_held link

    Returns true if the specific button is being held. args.inputs.controller_(one-four).key_held.BUTTON will be true for all frames after key_down (until released).

    key_up link

    Returns true if the specific button was released. args.inputs.controller_(one-four).key_up.BUTTON will be true only on the frame the button was released.

    Keyboard (args.inputs.keyboard) link

    Represents the user's keyboard.

    active link

    Returns Kernel.tick_count (args.state.tick_count) if any keys on the keyboard were pressed.

    has_focus link

    Returns true if the game has keyboard focus.

    up link

    Returns true if up or w is pressed or held on the keyboard.

    down link

    Returns true if down or s is pressed or held on the keyboard.

    left link

    Returns true if left or a is pressed or held on the keyboard.

    right link

    Returns true if right or d is pressed or held on the keyboard.

    left_right link

    Returns -1 (left), 0 (neutral), or +1 (right) depending on results of args.inputs.keyboard.left and args.inputs.keyboard.right.

    up_down link

    Returns -1 (left), 0 (neutral), or +1 (right) depending on results of args.inputs.keyboard.up and args.inputs.keyboard.up.

    keyboard properties link

    The following properties represent keys on the keyboard and are available on args.inputs.keyboard.KEY, args.inputs.keyboard.key_down.KEY, args.inputs.keyboard.key_held.KEY, and args.inputs.keyboard.key_up.KEY:

    char link

    Method is available under inputs.key_down, inputs.key_held, and inputs.key_up. Take note that

    args.inputs.keyboard.key_held.char will only return the ascii value of the last key that was held. Use args.inputs.keyboard.key_held.truthy_keys to get an Array of Symbols representing all keys being held.

    To get a picture of all key states args.inputs.keyboard.keys returns a Hash with the following keys: :down, :held, :down_or_held, :up.

    NOTE: args.inputs.keyboard.key_down.char will be set in line with key repeat behavior of your OS.

    This is a demonstration of the behavior (see ./samples/02_input_basics/01_keyboard for a more detailed example): 

    def tick args
  # uncomment the line below to see the value changes at a slower rate
  # $gtk.slowmo! 30

  keyboard = args.inputs.keyboard

  args.outputs.labels << { x: 30,
                           y: 720,
                           text: "use the J key to test" }

  args.outputs.labels << { x: 30,
                           y: 720 - 30,
                           text: "key_down.char: #{keyboard.key_down.char.inspect}" }

  args.outputs.labels << { x: 30,
                           y: 720 - 60,
                           text: "key_down.j:    #{keyboard.key_down.j}" }

  args.outputs.labels << { x: 30,
                           y: 720 - 30,
                           text: "key_held.char: #{keyboard.key_held.char.inspect}" }

  args.outputs.labels << { x: 30,
                           y: 720 - 60,
                           text: "key_held.j:    #{keyboard.key_held.j}" }

  args.outputs.labels << { x: 30,
                           y: 720 - 30,
                           text: "key_up.char:   #{keyboard.key_up.char.inspect}" }

  args.outputs.labels << { x: 30,
                           y: 720 - 60,
                           text: "key_up.j:      #{keyboard.key_up.j}" }
end

    keys link

    Returns a Hash with all keys on the keyboard in their respective state. The Hash contains the following keys

    Runtime (args.gtk) link

    The GTK::Runtime class is the core of DragonRuby. It is globally accessible via $gtk or inside of the tick method through args. 

    def tick args
  args.gtk # accessible like this
  $gtk # or like this
end

    Class Macros link

    The following class macros are available within DragonRuby.

    attr link

    The attr class macro is an alias to attr_accessor.

    Instead of: 

    class Player
  attr_accessor :hp, :armor
end

    You can do: 

    class Player
  attr :hp, :armor
end

    attr_gtk link

    As the size/complexity of your game increases. You may want to create classes to organize everything. The attr_gtk class macro adds DragonRuby's environment methods (such as args.state, args.inputs, args.outputs, args.audio, etc) to your class so you don't have to pass args around everwhere.

    Instead of: 

    class Game
  def tick args
    defaults args
    calc args
    render args
  end

  def defaults args
    args.state.space_pressed_at ||= 0
  end

  def calc args
    if args.inputs.keyboard.key_down.space
      args.state.space_pressed_at = args.state.tick_count
    end
  end

  def render args
    if args.state.space_pressed_at == 0
      args.outputs.labels << { x: 100, y: 100,
                               text: "press space" }
    else
      args.outputs.labels << { x: 100, y: 100,
                               text: "space was pressed at: #{args.state.space_pressed_at}" }
    end
  end
end

def tick args
  $game ||= Game.new
  $game.tick args
end

    You can do: 

    class Game
  attr_gtk # attr_gtk class macro

  def tick
    defaults
    calc
    render
  end

  def defaults
    state.space_pressed_at ||= 0
  end

  def calc
    if inputs.keyboard.key_down.space
      state.space_pressed_at = state.tick_count
    end
  end

  def render
    if state.space_pressed_at == 0
      outputs.labels << { x: 100, y: 100,
                          text: "press space" }
    else
      outputs.labels << { x: 100, y: 100,
                          text: "space was pressed at: #{state.space_pressed_at}" }
    end
  end
end

def tick args
  $game ||= Game.new
  $game.args = args # set args property on game
  $game.tick        # call tick without passing in args
end

$game = nil

    Indie and Pro Functions link

    The following functions are only available at the Indie and Pro License tiers.

    get_pixels link

    Given a file_path to a sprite, this function returns a one dimensional array of hexadecimal values representing the ARGB of each pixel in a sprite.

    See the following sample app for a full demonstration of how to use this function: ./samples/07_advanced_rendering/06_pixel_arrays_from_file

    dlopen link

    Loads a precompiled C Extension into your game.

    See the sample apps at ./samples/12_c_extensions for detailed walkthroughs of creating C extensions.

    Environment and Utility Functions link

    The following functions will help in interacting with the OS and rendering pipeline.

    calcstringbox link

    Returns the render width and render height as a tuple for a piece of text. The parameters this method takes are: 

    def tick args
  text = "a piece of text"
  size_enum = 5 # "large font size"

  # path is relative to your game directory (eg mygame/fonts/courier-new.ttf)
  font = "fonts/courier-new.ttf"

  # get the render width and height
  string_w, string_h = args.gtk.calcstringbox text, size_enum, font

  # render the label
  args.outputs.labels << {
    x: 100,
    y: 100,
    text: text,
    size_enum: size_enum,
    font: font
  }

  # render a border around the label based on the results from calcstringbox
  args.outputs.borders << {
    x: 100,
    y: 100,
    w: string_w,
    h: string_h,
    r: 0,
    g: 0,
    b: 0
  }
end

    request_quit link

    Call this function to exit your game. You will be given one additional tick if you need to perform any housekeeping before that game closes. 

    def tick args
  # exit the game after 600 frames (10 seconds)
  if args.state.tick_count == 600
    args.gtk.request_quit
  end
end

    quit_requested? link

    This function will return true if the game is about to exit (either from the user closing the game or if request_quit was invoked).

    set_window_fullscreen link

    This function takes in a single boolean parameter. true to make the game fullscreen, false to return the game back to windowed mode. 

    def tick args
  # make the game full screen after 600 frames (10 seconds)
  if args.state.tick_count == 600
    args.gtk.set_window_fullscreen true
  end

  # return the game to windowed mode after 20 seconds
  if args.state.tick_count == 1200
    args.gtk.set_window_fullscreen false
  end
end

    window_fullscreen? link

    Returns true if the window is currently in fullscreen mode.

    set_window_scale link

    This function takes in a float value and uses that to resize the game window to a percentage of 1280x720 (or 720x1280 in portrait mode). The valid scale options are 0.1, 0.25, 0.5, 0.75, 1.25, 1.5, 2.0, 2.5, 3.0, and 4.0. The float value you pass in will be floored to the nearest valid scale option.

    platform? link

    You can ask DragonRuby which platform your game is currently being run on. This can be useful if you want to perform different pieces of logic based on where the game is running.

    The raw platform string value is available via args.gtk.platform which takes in a symbol representing the platform's categorization/mapping.

    You can see all available platform categorizations via the args.gtk.platform_mappings function.

    Here's an example of how to use args.gtk.platform? category_symbol: 

    def tick args
  label_style = { x: 640, y: 360, anchor_x: 0.5, anchor_y: 0.5 }
  if    args.gtk.platform? :macos
    args.outputs.labels << { text: "I am running on MacOS.", **label_style }
  elsif args.gtk.platform? :win
    args.outputs.labels << { text: "I am running on Windows.", **label_style }
  elsif args.gtk.platform? :linux
    args.outputs.labels << { text: "I am running on Linux.", **label_style }
  elsif args.gtk.platform? :web
    args.outputs.labels << { text: "I am running on a web page.", **label_style }
  elsif args.gtk.platform? :android
    args.outputs.labels << { text: "I am running on Android.", **label_style }
  elsif args.gtk.platform? :ios
    args.outputs.labels << { text: "I am running on iOS.", **label_style }
  elsif args.gtk.platform? :touch
    args.outputs.labels << { text: "I am running on a device that supports touch (either iOS/Android native or mobile web).", **label_style }
  elsif args.gtk.platform? :steam
    args.outputs.labels << { text: "I am running via steam (covers both desktop and steamdeck).", **label_style }
  elsif args.gtk.platform? :steam_deck
    args.outputs.labels << { text: "I am running via steam on the Steam Deck (not steam desktop).", **label_style }
  elsif args.gtk.platform? :steam_desktop
    args.outputs.labels << { text: "I am running via steam on desktop (not steam deck).", **label_style }
  end
end

    production? link

    Returns true if the game is being run in a released/shipped state.

    If you want to simulate a production build. Add an empty file called dragonruby_production_build inside of the metadata folder. This will turn of all logging and all creation of temp files used for development purposes.

    platform_mappings link

    These are the current platform categorizations (args.gtk.platform_mappings): 

    {
  "Mac OS X"   => [:desktop, :macos, :osx, :mac, :macosx], # may also include :steam and :steam_desktop run via steam
  "Windows"    => [:desktop, :windows, :win],              # may also include :steam and :steam_desktop run via steam
  "Linux"      => [:desktop, :linux, :nix],                # may also include :steam and :steam_desktop run via steam
  "Emscripten" => [:web, :wasm, :html, :emscripten],       # may also include :touch if running in the web browser on mobile
  "iOS"        => [:mobile, :ios, :touch],
  "Android"    => [:mobile, :android, :touch],
  "Steam Deck" => [:steamdeck, :steam_deck, :steam],
}

    Given the mappings above, args.gtk.platform? :desktop would return true if the game is running on a player's computer irrespective of OS (MacOS, Linux, and Windows are all categorized as :desktop platforms).

    open_url link

    Given a uri represented as a string. This fuction will open the uri in the user's default browser. 

    def tick args
  # open a url after 600 frames (10 seconds)
  if args.state.tick_count == 600
    args.gtk.open_url "http://dragonruby.org"
  end
end

    system link

    Given an OS dependent cli command represented as a string, this function executes the command and puts the results to the DragonRuby Console (returns nil). 

    def tick args
  # execute ls on the current directory in 10 seconds
  if args.state.tick_count == 600
    args.gtk.system "ls ."
  end
end

    exec link

    Given an OS dependent cli command represented as a string, this function executes the command and returns a string representing the results. 

    def tick args
  # execute ls on the current directory in 10 seconds
  if args.state.tick_count == 600
    results = args.gtk.exec "ls ."
    puts "The results of the command are:"
    puts results
  end
end

    show_cursor link

    Shows the mouse cursor.

    hide_cursor link

    Hides the mouse cursor.

    cursor_shown? link

    Returns true if the mouse cursor is visible.

    set_mouse_grab link

    Takes in a numeric parameter representing the mouse grab mode.

    set_system_cursor link

    Takes in a string value of "arrow", "ibeam", "wait", or "hand" and sets the mouse curosor to the corresponding system cursor (if available on the OS).

    set_cursor link

    Replaces the mouse cursor with a sprite. Takes in a path to the sprite, and optionally an x and y value representing the realtive positioning the sprite will have to the mouse cursor. 

    def tick args
  if args.state.tick_count == 0
    # assumes a sprite of size 80x80 and centers the sprite
    # relative to the cursor position.
    args.gtk.set_cursor "sprites/square/blue.png", 40, 40
  end
end

    File IO Functions link

    The following functions give you the ability to interact with the file system.

    IMPORTANT: File access functions are sandoxed and assume that the dragonruby binary lives alongside the game you are building. Do not expect these functions to return correct values if you are attempting to run the dragonruby binary from a shared location. It's recommended that the directory structure contained in the zip is not altered and games are built using that starter template.

    list_files link

    This function takes in one parameter. The parameter is the directory path and assumes the the game directory is the root. The method returns an Array of String representing all files within the directory. Use stat_file to determine whether a specific path is a file or a directory.

    stat_file link

    This function takes in one parameter. The parameter is the file path and assumes the the game directory is the root. The method returns nil if the file doesn't exist otherwise it returns a Hash with the following information: 

    # {
#   path: String,
#   file_size: Int,
#   mod_time: Int,
#   create_time: Int,
#   access_time: Int,
#   readonly: Boolean,
#   file_type: Symbol (:regular, :directory, :symlink, :other),
# }

def tick args
  if args.inputs.mouse.click
    args.gtk.write_file "last-mouse-click.txt", "Mouse was clicked at #{args.state.tick_count}."
  end

  file_info = args.gtk.stat_file "last-mouse-click.txt"

  if file_info
    args.outputs.labels << {
      x: 30,
      y: 30.from_top,
      text: file_info.to_s,
      size_enum: -3
    }
  else
    args.outputs.labels << {
      x: 30,
      y: 30.from_top,
      text: "file does not exist, click to create file",
      size_enum: -3
    }
  end
end

    read_file link

    Given a file path, a string will be returned representing the contents of the file. nil will be returned if the file does not exist. You can use stat_file to get additional information of a file.

    write_file link

    This function takes in two parameters. The first parameter is the file path and assumes the the game directory is the root. The second parameter is the string that will be written. The method **overwrites** whatever is currently in the file. Use append_file to append to the file as opposed to overwriting. 

    def tick args
  if args.inputs.mouse.click
    args.gtk.write_file "last-mouse-click.txt", "Mouse was clicked at #{args.state.tick_count}."
  end
end

    append_file link

    This function takes in two parameters. The first parameter is the file path and assumes the the game directory is the root. The second parameter is the string that will be written. The method appends to whatever is currently in the file (a new file is created if one does not alread exist). Use write_file to overwrite the file's contents as opposed to appending. 

    def tick args
  if args.inputs.mouse.click
    args.gtk.write_file "last-mouse-click.txt", "Mouse was clicked at #{args.state.tick_count}."
  end
end

    delete_file link

    This function takes in a single parameters. The parameter is the file path that should be deleted. This function will raise an exception if the path requesting to be deleted does not exist.

    Notes:

    Here is a list of reasons an exception could be raised:

    - If the path is not found. - If the path is still open (for reading or writing). - If the path is not a file or directory. - If the path is a circular symlink. - If you do not have permissions to delete the path. - If the directory attempting to be deleted is not empty. 

    def tick args
  if args.inputs.mouse.click
    args.gtk.write_file "last-mouse-click.txt", "Mouse was clicked at #{args.state.tick_count}."
  end
end

    delete_file_if_exist link

    Has the same behavior as delete_file except this function does not throw an exception.

    XML and JSON link

    The following functions help with parsing xml and json.

    parse_json link

    Given a json string, this function returns a hash representing the json data. 

    hash = args.gtk.parse_json '{ "name": "John Doe", "aliases": ["JD"] }'
# structure of hash: { "name"=>"John Doe", "aliases"=>["JD"] }

    parse_json_file link

    Same behavior as parse_json_file except a file path is read for the json string.

    parse_xml link

    Given xml data as a string, this function will return a hash that represents the xml data in the following recursive structure: 

    
type: :element,
name: "Person",
children: [...]

    parse_xml_file link

    Function has the same behavior as parse_xml except that the parameter must be a file path that contains xml contents.

    Network IO Functions link

    The following functions help with interacting with the network.

    http_get link

    Returns an object that represents an http response which will eventually have a value. This http_get method is invoked asynchronously. Check for completion before attempting to read results. 

    def tick args
  # perform an http get and print the response when available
  args.state.result ||= args.gtk.http_get "https://httpbin.org/html"

  if args.state.result && args.state.result[:complete] && !args.state.printed
    if args.state.result[:http_response_code] == 200
      puts "The response was successful. The body is:"
      puts args.state.result[:response_data]
    else
      puts "The response failed. Status code:"
      puts args.state.result[:http_response_code]
    end
    # set a flag denoting that the response has been printed
    args.state.printed = true

    # show the console
    args.gtk.show_console
  end
end

    http_post link

    Returns an object that represents an http response which will eventually have a value. This http_post method is invoked asynchronously. Check for completion before attempting to read results. 

    def tick args
  # perform an http get and print the response when available

  args.state.form_fields ||= { "userId" => "1705280157" }
  args.state.result ||= args.gtk.http_post "http://httpbin.org/post",
                                           args.state.form_fields,
                                           ["Content-Type: application/x-www-form-urlencoded"]


  if args.state.result && args.state.result[:complete] && !args.state.printed
    if args.state.result[:http_response_code] == 200
      puts "The response was successful. The body is:"
      puts args.state.result[:response_data]
    else
      puts "The response failed. Status code:"
      puts args.state.result[:http_response_code]
    end
    # set a flag denoting that the response has been printed
    args.state.printed = true

    # show the console
    args.gtk.show_console
  end
end

    http_post_body link

    Returns an object that represents an http response which will eventually have a value. This http_post_body method is invoked asynchronously. Check for completion before attempting to read results. 

    def tick args
  # perform an http get and print the response when available

  args.state.json ||= "{ "userId": "#{Time.now.to_i}"}"
  args.state.result ||= args.gtk.http_post_body "http://httpbin.org/post",
                                                args.state.json,
                                                ["Content-Type: application/json", "Content-Length: #{args.state.json.length}"]


  if args.state.result && args.state.result[:complete] && !args.state.printed
    if args.state.result[:http_response_code] == 200
      puts "The response was successful. The body is:"
      puts args.state.result[:response_data]
    else
      puts "The response failed. Status code:"
      puts args.state.result[:http_response_code]
    end
    # set a flag denoting that the response has been printed
    args.state.printed = true

    # show the console
    args.gtk.show_console
  end
end

    start_server! link

    Starts a in-game http server that can be process http requests. When your game is running in development mode. A dev server is started at http://localhost:9001

    You can start an in-game http server in production via: 

    def tick args
  # server explicitly enabled in production
  args.gtk.start_server! port: 9001, enable_in_prod: true
end

    Here's how you would responde to http requests: 

    def tick args
  # server explicitly enabled in production
  args.gtk.start_server! port: 9001, enable_in_prod: true

  # loop through pending requests and respond to them
  args.inputs.http_requests.each do |request|
    puts "#{request}"
    request.respond 200, "ok"
  end
end

    Developer Support Functions link

    The following functions help support the development process. It is not recommended to use this functions in "production" game logic.

    version link

    Returns a string representing the version of DragonRuby you are running.

    version_pro? link

    Returns true if the version of DragonRuby is NOT Standard Edition.

    reset link

    Resets DragonRuby's internal state as if it were just started. args.state.tick_count is set to 0 and args.state is cleared of any values. This function is helpful when you are developing your game and want to reset everything as if the game just booted up. 

    def tick args
end

# reset the game if this file is hotloaded/required
# (removes the need to press "r" when I file is updated)
$gtk.reset

    Resetting iVars (advanced)

    NOTE: args.gtk.reset does not reset global variables or instance of classes you have have constructed. If you want to also reset global variables or instances of classes when $gtk.reset is called. Define a reset method. Here's an example: 

    class Game
  def initialize
    puts "Game initialize called"
  end
end

def tick args
  $game ||= Game.new

  if args.state.tick_count == 0
    puts "tick_count is 0"
  end

  # if r is pressed on the keyboard, reset the game
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
  end
end

# custom reset function
def reset
  puts "Custom reset function was called."
  $game = nil
end

    seed and RNG (advanced)

    Optionally, $gtk.reset (args.gtk.reset) can take in a named parameter for RNG called seed:. Passing in seed: will reset RNG so that rand returns a repeatable set of random numbers. This seed value is initialized with the start time of your game ($gtk.started_at). Having this option is is helpful for replays and unit tests.

    Don't worry about this capability if you aren't using DragonRuby's unit testing, or replay capabilities.

    Here is the behavior of $gtk.reset when given a seed: 

    def tick args
  if args.state.tick_count == 0
    puts rand
    puts rand
    puts rand
    puts rand
  end
end

puts "Started at (RNG seed inital value)"
puts $gtk.started_at # Time as an integer that your game was started at

puts "Seed value that will be used on reset"
puts $gtk.seed # current value that RNG was seeded with

# reset the game and use the last seed to reset RNG
$gtk.reset

# === OR ===
# sets the seed value to predefined value
# subsequent resets will use the new predefined value
# $gtk.reset seed: 100
# (or shorthand)
# $gtk.reset 100

# sets the seed back to its original value
# $gtk.reset seed: $gtk.started_at

    If you want to set RNG without resetting your game state, you can use $gtk.set_rng VALUE.

    reset_next_tick link

    Has the same behavior as reset except the reset occurs before tick is executed again. reset resets the environment immediately (while the tick method is inflight). It's recommended that reset should be called outside of the tick method (invoked when a file is saved/hotloaded), and reset_next_tick be used inside of the tick method so you don't accidentally blow away state the your game depends on to complete the current tick without exceptions. 

    def tick args
  # reset the game if "r" is pressed on the keyboard
  if args.inputs.keyboard.key_down.r
    args.gtk.reset_next_tick # use reset_next_tick instead of reset
  end
end

# reset the game if this file is hotloaded/required
# (removes the need to press "r" when I file is updated)
$gtk.reset

    reset_sprite link

    Sprites when loaded are cached. Given a string parameter, this method invalidates the cache record of a sprite so that updates on from the disk can be loaded.

    reset_sprites link

    Sprites when loaded are cached. This method invalidates the cache record of all sprites so that updates on from the disk can be loaded. This function is automatically called when args.gtk.reset ($gtk.reset) is invoked.

    calcspritebox link

    Given a path to a sprite, this method returns the width and height of a sprite as a tuple.

    NOTE: This method should be used for development purposes only and is expensive to call every frame. Do not use this method to set the size of sprite when rendering (hard code those values since you know what they are beforehand).

    current_framerate link

    Returns a float value representing the framerate of your game. This is an approximation/moving average of your framerate and should eventually settle to 60fps. 

    def tick args
  # render a label to the screen that shows the current framerate
  # formatted as a floating point number with two decimal places
  args.outputs.labels << { x: 30, y: 30.from_top, text: "#{args.gtk.current_framerate.to_sf}" }
end

    framerate_diagnostics_primitives link

    Returns a set of primitives that can be rendered to the screen which provide more detailed information about the speed of your simulation (framerate, draw call count, mouse position, etc). 

    def tick args
  args.outputs.primitives << args.gtk.framerate_diagnostics_primitives
end

    warn_array_primitives! link

    This function helps you audit your game of usages of array-based primitives. While array-based primitives are simple to create and use, they are slower to process than Hash or Class based primitives. 

    def tick args
  # enable array based primitives warnings
  args.gtk.warn_array_primitives!

  # array-based primitive elsewhere in code
  # an log message will be posted giving the location of the array
  # based primitive usage
  args.outputs.sprites << [100, 100, 200, 200, "sprites/square/blue.png"]

  # instead of using array based primitives, migrate to hashes as needed
  args.outputs.sprites << {
    x: 100,
    y: 100,
    w: 200,
    h: 200, path:
    "sprites/square/blue.png"
  }
end

    benchmark link

    You can use this function to compare the relative performance of blocks of code. 

    def tick args
  # press r to run benchmark
  if args.inputs.keyboard.key_down.r
    args.gtk.console.show
    args.gtk.benchmark iterations: 1000, # number of iterations
                       # label for experiment
                       using_numeric_map: -> () {
                         # experiment body
                         v = 100.map_with_index do |i|
                           i * 100
                         end
                       },
                       # label for experiment
                       using_numeric_times: -> () {
                         # experiment body
                         v = []
                         100.times do |i|
                           v << i * 100
                         end
                       }
  end
end

    notify! link

    Given a string, this function will present a message at the bottom of your game. This method is only invoked in dev mode and is useful for debugging.

    An optional parameter of duration (number value representing ticks) can also be passed in. The default value if 300 ticks (5 seconds). 

    def tick args
  if args.inputs.mouse.click
    args.gtk.notify! "Mouse was clicked!"
  end

  if args.inputs.keyboard.key_down.r
    # optional duration parameter
    args.gtk.notify! "R key was pressed!", 600 # present message for 10 seconds/600 frames
  end
end

    notify_extended! link

    Has similar behavior as notify! except you have additional options to show messages in a production environment. 

    def tick args
  if args.inputs.mouse.click
    args.gtk.notify_extended! message: "message",
                              duration: 300,
                              env: :prod
  end
end

    slowmo! link

    Given a numeric value representing the factor of 60fps. This function will bring your simulation loop down to slower rate. This method is intended to be used for debugging purposes. 

    def tick args
  # set your simulation speed to (15 fps): args.gtk.slowmo! 4
  # set your simulation speed to (1 fps): args.gtk.slowmo! 60
  # set your simulation speed to (30 fps):
  args.gtk.slowmo! 2
end

    Remove this line from your tick method will automatically set your simulation speed back to 60 fps.

    show_console link

    Shows the DragonRuby console. Useful when debugging/customizing an in-game dev workflow.

    hide_console link

    Shows the DragonRuby console. Useful when debugging/customizing an in-game dev workflow.

    enable_console link

    Enables the DragonRuby Console so that it can be presented by pressing the tilde key (the key next to the number 1 key).

    disable_console link

    Disables the DragonRuby Console so that it won't show up even if you press the tilde key or call args.gtk.show_console.

    disable_reset_via_ctrl_r link

    By default, pressing CTRL+R invokes $gtk.reset_next_tick (safely resetting your game with a convenient key combo).

    If you want to disable this behavior, add the following to the main.rb: 

    def tick args
  ...
end

$gtk.disable_reset_via_ctrl_r

    NOTE: $gtk.disable_console will also disable the CTRL+R reset behavior.

    start_recording link

    Resets the game to tick 0 and starts recording gameplay. Useful for visual regression tests/verification.

    stop_recording link

    Function takes in a destination file for the currently recording gameplay. This file can be used to replay a recording.

    cancel_recording link

    Function cancels a gameplay recording session and discards the replay.

    start_replay link

    Given a file that represents a recording, this method will run the recording against the current codebase.

    You can start a replay from the command line also: 

    # first argument: the game directory
# --replay switch is the file path relative to the game directory
# --speed switch is optional. a value of 4 will run the replay and game at 4x speed
# cli command example is in the context of Linux and Mac, for Windows the binary would be ./dragonruby.exe
./dragonruby ./mygame --replay ./replay.txt --speed 4

    stop_replay link

    Function stops a replay that is currently executing.

    get_base_dir link

    Returns the path to the location of the dragonruby binary. In production mode, this value will be the same as the value returned by get_game_dir. Function should only be used for debugging/development workflows.

    get_game_dir link

    Returns the location within sandbox storage that the game is running. When developing your game, this value will be your mygame directory. In production, it'll return a value that is OS specific (eg the Roaming directory on Windows or the Application Support directory on Mac).

    Invocations of ~(write|append)_file will write to this sandboxed directory.

    get_game_dir_url link

    Returns a url encoded string representing the sandbox location for game data.

    open_game_dir link

    Opens the game directory in the OS's file explorer. This should be used for debugging purposes only.

    write_file_root link

    Given a file path and contents, the contents will be written to a directory outside of the game directory. This method should be used for development purposes only. In production this method will write to the same sandboxed location as write_file.

    append_file_root link

    Has the same behavior as write_file_root except that it appends the contents as opposed to overwriting them.

    argv link

    Returns a string representing the command line arguments passed to the DragonRuby binary. This should be used for development/debugging purposes only.

    cli_arguments link

    Returns a Hash for command line arguments in the format of --switch value (two hyphens preceding the switch flag with the value seperated by a space). This should be used for development/debugging purposes only.

    download_stb_rb(_raw) link

    These two functions can help facilitate the integration of external code files. OSS contributors are encouraged to create libraries that all fit in one file (lowering the barrier to entry for adoption).

    Examples: 

    def tick args
end

# option 1:
# source code will be downloaded from the specified GitHub url, and saved locally with a
# predefined folder convension.
$gtk.download_stb_rb "https://github.com/xenobrain/ruby_vectormath/blob/main/vectormath_2d.rb"

# option 2:
# source code will be downloaded from the specified GitHub username, repository, and file.
# code will be saved locally with a predefined folder convension.
$gtk.download_stb_rb "xenobrain", "ruby_vectormath", "vectormath_2d.rb"

# option 3:
# source code will be downloaded from a direct/raw url and saved to a direct/raw local path.
$gtk.download_stb_rb_raw "https://raw.githubusercontent.com/xenobrain/ruby_vectormath/main/vectormath_2d.rb",
                         "lib/xenobrain/ruby_vectionmath/vectormath_2d.rb"

    reload_history link

    Returns a Hash representing the code files that have be loaded for your game along with timings for the events. This should be used for development/debugging purposes only.

    reload_history_pending link

    Returns a Hash for files that have been queued for reload, but haven't been processed yet. This should be used for development/debugging purposes only.

    reload_if_needed link

    Given a file name, this function will queue the file for reload if it's been modified. An optional second parameter can be passed in to signify if the file should be forced loaded regardless of modified time (true means to force load, false means to load only if the file has been modified). This function should be used for development/debugging purposes only.

    State (args.state) link

    Store your game state inside of this state. Properties with arbitrary nesting is allowed and a backing Entity will be created on your behalf. 

    def tick args
  args.state.player.x ||= 0
  args.state.player.y ||= 0
end

    entity_id link

    Entities automatically receive an entity_id of type Fixnum.

    entity_type link

    Entities can have an entity_type which is represented as a Symbol.

    created_at link

    Entities have created_at set to args.state.tick_count when they are created.

    created_at_elapsed link

    Returns the elapsed number of ticks since creation.

    global_created_at link

    Entities have global_created_at set to Kernel.global_tick_count when they are created.

    global_created_at_elapsed link

    Returns the elapsed number of global ticks since creation.

    as_hash link

    Entity cast to a Hash so you can update values as if you were updating a Hash.

    new_entity link

    Creates a new Entity with a type, and initial properties. An option block can be passed to change the newly created entity: 

    def tick args
  args.state.player ||= args.state.new_entity :player, x: 0, y: 0 do |e|
    e.max_hp = 100
    e.hp     = e.max_hp * rand
  end
end

    new_entity_strict link

    Creates a new Strict Entity. While Entities created via args.state.new_entity can have new properties added later on, Entities created using args.state.new_entity_strict must define all properties that are allowed during its initialization. Attempting to add new properties after initialization will result in an exception.

    args.state.tick_count link

    Returns the current tick of the game. args.state.tick_count is 0 when the game is first started or if the game is reset via $gtk.reset.

    add_caller_to_puts! link

    If you need to hund down rogue puts statements in your code do: 

    def tick args
  # adding the following line to the TOP of your tick method
  # will print ~caller~ along side each ~puts~ statement
  $gtk.add_caller_to_puts!
end

    Geometry (args.geometry) link

    The Geometry module contains methods for calculations that are frequently used in game development.

    The following functions of Geometry are mixed into Hash, Array, and DragonRuby's Entity class:

    You can invoke the functions above using either the mixin variant or the module variant. Example: 

    def tick args
  # define to rectangles
  rect_1 = { x: 0, y: 0, w: 100, h: 100 }
  rect_2 = { x: 50, y: 50, w: 100, h: 100 }

  # mixin variant
  # call geometry method function from instance of a Hash class
  puts rect_1.intersect_rect?(rect_2)

  # OR

  # module variants
  puts args.geometry.intersect_rect?(rect_1, rect_2)
  puts Geometry.intersect_rect?(rect_1, rect_2)
end

    intersect_rect? link

    Invocation variants:

    Given two rectangle primitives this function will return true or false depending on if the two rectangles intersect or not. An optional final parameter can be passed in representing the tolerence of overlap needed to be considered a true intersection. The default value of tolerance is 0.1 which keeps the function from returning true if only the edges of the rectangles overlap.

    :anchor_x, and anchor_y is taken into consideration if the objects respond to these methods.

    Here is an example where one rectangle is stationary, and another rectangle is controlled using directional input. The rectangles change color from blue to read if they intersect. 

    def tick args
  # define a rectangle in state and position it
  # at the center of the screen with a color of blue
  args.state.box_1 ||= {
    x: 640 - 20,
    y: 360 - 20,
    w: 40,
    h: 40,
    r: 0,
    g: 0,
    b: 255
  }

  # create another rectangle in state and position it
  # at the far left center
  args.state.box_2 ||= {
    x: 0,
    y: 360 - 20,
    w: 40,
    h: 40,
    r: 0,
    g: 0,
    b: 255
  }

  # take the directional input and use that to move the second rectangle around
  # increase or decrease the x value based on if left or right is held
  args.state.box_2.x += args.inputs.left_right * 5
  # increase or decrease the y value based on if up or down is held
  args.state.box_2.y += args.inputs.up_down * 5

  # change the colors of the rectangles based on whether they
  # intersect or not
  if args.state.box_1.intersect_rect? args.state.box_2
    args.state.box_1.r = 255
    args.state.box_1.g = 0
    args.state.box_1.b = 0

    args.state.box_2.r = 255
    args.state.box_2.g = 0
    args.state.box_2.b = 0
  else
    args.state.box_1.r = 0
    args.state.box_1.g = 0
    args.state.box_1.b = 255

    args.state.box_2.r = 0
    args.state.box_2.g = 0
    args.state.box_2.b = 255
  end

  # render the rectangles as border primitives on the screen
  args.outputs.borders << args.state.box_1
  args.outputs.borders << args.state.box_2
end

    inside_rect? link

    Invocation variants:

    Given two rectangle primitives this function will return true or false depending on if the first rectangle (or self) is inside of the second rectangle.

    Here is an example where one rectangle is stationary, and another rectangle is controlled using directional input. The rectangles change color from blue to read if the movable rectangle is entirely inside the stationary rectangle.

    :anchor_x, and anchor_y is taken into consideration if the objects respond to these methods. 

    def tick args
  # define a rectangle in state and position it
  # at the center of the screen with a color of blue
  args.state.box_1 ||= {
    x: 640 - 40,
    y: 360 - 40,
    w: 80,
    h: 80,
    r: 0,
    g: 0,
    b: 255
  }

  # create another rectangle in state and position it
  # at the far left center
  args.state.box_2 ||= {
    x: 0,
    y: 360 - 10,
    w: 20,
    h: 20,
    r: 0,
    g: 0,
    b: 255
  }

  # take the directional input and use that to move the second rectangle around
  # increase or decrease the x value based on if left or right is held
  args.state.box_2.x += args.inputs.left_right * 5
  # increase or decrease the y value based on if up or down is held
  args.state.box_2.y += args.inputs.up_down * 5

  # change the colors of the rectangles based on whether they
  # intersect or not
  if args.state.box_2.inside_rect? args.state.box_1
    args.state.box_1.r = 255
    args.state.box_1.g = 0
    args.state.box_1.b = 0

    args.state.box_2.r = 255
    args.state.box_2.g = 0
    args.state.box_2.b = 0
  else
    args.state.box_1.r = 0
    args.state.box_1.g = 0
    args.state.box_1.b = 255

    args.state.box_2.r = 0
    args.state.box_2.g = 0
    args.state.box_2.b = 255
  end

  # render the rectangles as border primitives on the screen
  args.outputs.borders << args.state.box_1
  args.outputs.borders << args.state.box_2
end

    scale_rect link

    Given a Rectangle this function returns a new rectangle with a scaled size. 

    def tick args
  # a rect at the center of the screen
  args.state.rect_1 ||= { x: 640 - 20, y: 360 - 20, w: 40, h: 40 }

  # render the rect
  args.outputs.borders << args.state.rect_1

  # the rect half the size with the x and y position unchanged
  args.outputs.borders << args.state.rect_1.scale_rect(0.5)

  # the rect double the size, repositioned in the center given anchor optional arguments
  args.outputs.borders << args.state.rect_1.scale_rect(2, 0.5, 0.5)
end

    scale_rect_extended link

    The behavior is similar to scale_rect except that you can independently control the scale of each axis. The parameters are all named: 

    def tick args
  baseline_rect = { x: 640 - 20, y: 360 - 20, w: 40, h: 40 }
  args.state.rect_1 ||= baseline_rect
  args.state.rect_2 ||= baseline_rect.scale_rect_extended(percentage_x: 2,
                                                          percentage_y: 0.5,
                                                          anchor_x: 0.5,
                                                          anchor_y: 1.0)
  args.outputs.borders << args.state.rect_1
  args.outputs.borders << args.state.rect_2
end

    anchor_rect link

    Returns a new rect that is anchored by an anchor_x and anchor_y value. The width and height of the rectangle is taken into consideration when determining the anchor position: 

    def tick args
  args.state.rect ||= {
    x: 640,
    y: 360,
    w: 100,
    h: 100
  }

  # rect's center: 640 + 50, 360 + 50
  args.outputs.borders << args.state.rect.anchor_rect(0, 0)

  # rect's center: 640, 360
  args.outputs.borders << args.state.rect.anchor_rect(0.5, 0.5)

  # rect's center: 640, 360
  args.outputs.borders << args.state.rect.anchor_rect(0.5, 0)
end

    angle_from link

    Invocation variants:

    Returns an angle in degrees from the end_point to the start_point (if you want the value in radians, you can call .to_radians on the value returned): 

    def tick args
  rect_1 ||= {
    x: 0,
    y: 0,
  }

  rect_2 ||= {
    x: 100,
    y: 100,
  }

  angle = rect_1.angle_from rect_2 # returns 225 degrees
  angle_radians = angle.to_radians
  args.outputs.labels << { x: 30, y: 30.from_top, text: "#{angle}, #{angle_radians}" }

  angle = args.geometry.angle_from rect_1, rect_2 # returns 225 degrees
  angle_radians = angle.to_radians
  args.outputs.labels << { x: 30, y: 60.from_top, text: "#{angle}, #{angle_radians}" }
end

    angle_to link

    Invocation variants:

    Returns an angle in degrees to the end_point from the start_point (if you want the value in radians, you can call .to_radians on the value returned): 

    def tick args
  rect_1 ||= {
    x: 0,
    y: 0,
  }

  rect_2 ||= {
    x: 100,
    y: 100,
  }

  angle = rect_1.angle_to rect_2 # returns 45 degrees
  angle_radians = angle.to_radians
  args.outputs.labels << { x: 30, y: 30.from_top, text: "#{angle}, #{angle_radians}" }

  angle = args.geometry.angle_to rect_1, rect_2 # returns 45 degrees
  angle_radians = angle.to_radians
  args.outputs.labels << { x: 30, y: 60.from_top, text: "#{angle}, #{angle_radians}" }
end

    distance link

    Returns the distance between two points; 

    def tick args
  rect_1 ||= {
    x: 0,
    y: 0,
  }

  rect_2 ||= {
    x: 100,
    y: 100,
  }

  distance = args.geometry.distance rect_1, rect_2
  args.outputs.labels << {
    x: 30,
    y: 30.from_top,
    text: "#{distance}"
  }

  args.outputs.lines << {
    x: rect_1.x,
    y: rect_1.y,
    x2: rect_2.x,
    y2: rect_2.y
  }
end

    point_inside_circle? link

    Invocation variants:

    circle_center can also contain the radius value (instead of passing it as a separate argument).

    Returns true if a point is inside of a circle defined as a center point and radius. 

    def tick args
  # define circle center
  args.state.circle_center ||= {
    x: 640,
    y: 360
  }

  # define circle radius
  args.state.circle_radius ||= 100

  # define point
  args.state.point_1 ||= {
    x: 100,
    y: 100
  }

  # allow point to be moved using keyboard
  args.state.point_1.x += args.inputs.left_right * 5
  args.state.point_1.y += args.inputs.up_down * 5

  # determine if point is inside of circle
  intersection = args.geometry.point_inside_circle? args.state.point_1,
                                                    args.state.circle_center,
                                                    args.state.circle_radius

  # render point as a square
  args.outputs.sprites << {
    x: args.state.point_1.x - 20,
    y: args.state.point_1.y - 20,
    w: 40,
    h: 40,
    path: "sprites/square/blue.png"
  }

  # if there is an intersection, render a red circle
  # otherwise render a blue circle
  if intersection
    args.outputs.sprites << {
      x: args.state.circle_center.x - args.state.circle_radius,
      y: args.state.circle_center.y - args.state.circle_radius,
      w: args.state.circle_radius * 2,
      h: args.state.circle_radius * 2,
      path: "sprites/circle/red.png",
      a: 128
    }
  else
    args.outputs.sprites << {
      x: args.state.circle_center.x - args.state.circle_radius,
      y: args.state.circle_center.y - args.state.circle_radius,
      w: args.state.circle_radius * 2,
      h: args.state.circle_radius * 2,
      path: "sprites/circle/blue.png",
      a: 128
    }
  end
end

    center_inside_rect link

    Invocation variants:

    Given a target rect and a reference rect, the target rect is centered inside the reference rect (a new rect is returned). 

    def tick args
  rect_1 = {
    x: 0,
    y: 0,
    w: 100,
    h: 100
  }

  rect_2 = {
    x: 640 - 100,
    y: 360 - 100,
    w: 200,
    h: 200
  }

  centered_rect = args.geometry.center_inside_rect rect_1, rect_2
  # OR
  # centered_rect = rect_1.center_inside_rect rect_2

  args.outputs.solids << rect_1.merge(r: 255)
  args.outputs.solids << rect_2.merge(b: 255)
  args.outputs.solids << centered_rect.merge(g: 255)
end

    ray_test link

    Given a point and a line, ray_test returns one of the following symbols based on the location of the point relative to the line: :left, :right, :on 

    def tick args
  # create a point based off of the mouse location
  point = {
    x: args.inputs.mouse.x,
    y: args.inputs.mouse.y
  }

  # draw a line from the bottom left to the top right
  line = {
    x: 0,
    y: 0,
    x2: 1280,
    y2: 720
  }

  # perform ray_test on point and line
  ray = args.geometry.ray_test point, line

  # output the results of ray test at mouse location
  args.outputs.labels << {
    x: point.x,
    y: point.y + 25,
    text: "#{ray}",
    alignment_enum: 1,
    vertical_alignment_enum: 1,
  }

  # render line
  args.outputs.lines << line

  # render point
  args.outputs.solids << {
    x: point.x - 5,
    y: point.y - 5,
    w: 10,
    h: 10
  }
end

    line_rise_run link

    Given a line, this function returns a Hash with x and y keys representing a normalized representation of the rise and run of the line. 

    def tick args
  # draw a line from the bottom left to the top right
  line = {
    x: 0,
    y: 0,
    x2: 1280,
    y2: 720
  }

  # get rise and run of line
  rise_run = args.geometry.line_rise_run line

  # output the rise and run of line
  args.outputs.labels << {
    x: 640,
    y: 360,
    text: "#{rise_run}",
    alignment_enum: 1,
    vertical_alignment_enum: 1,
  }

  # render the line
  args.outputs.lines << line
end

    rotate_point link

    Given a point and an angle in degrees, a new point is returned that is rotated around the origin by the degrees amount. An optional third argument can be provided to rotate the angle around a point other than the origin. 

    def tick args
  args.state.rotate_amount ||= 0
  args.state.rotate_amount  += 1

  if args.state.rotate_amount >= 360
    args.state.rotate_amount = 0
  end

  point_1 = {
    x: 100,
    y: 100
  }

  # rotate point around 0, 0
  rotated_point_1 = args.geometry.rotate_point point_1,
                                               args.state.rotate_amount

  args.outputs.solids << {
    x: rotated_point_1.x - 5,
    y: rotated_point_1.y - 5,
    w: 10,
    h: 10
  }

  point_2 = {
    x: 640 + 100,
    y: 360 + 100
  }

  # rotate point around center screen
  rotated_point_2 = args.geometry.rotate_point point_2,
                                               args.state.rotate_amount,
                                               x: 640, y: 360

  args.outputs.solids << {
    x: rotated_point_2.x - 5,
    y: rotated_point_2.y - 5,
    w: 10,
    h: 10
  }
end

    find_intersect_rect link

    Given a rect and a collection of rects, find_intersect_rect returns the first rect that intersects with the the first parameter.

    :anchor_x, and anchor_y is taken into consideration if the objects respond to these methods.

    If you find yourself doing this: 

    collision = args.state.terrain.find { |t| t.intersect_rect? args.state.player }

    Consider using find_intersect_rect instead (it's more descriptive and faster): 

    collision = args.geometry.find_intersect_rect args.state.player, args.state.terrain

    find_all_intersect_rect link

    Given a rect and a collection of rects, find_all_intersect_rect returns all rects that intersects with the the first parameter.

    :anchor_x, and anchor_y is taken into consideration if the objects respond to these methods.

    If you find yourself doing this: 

    collisions = args.state.terrain.find_all { |t| t.intersect_rect? args.state.player }

    Consider using find_all_intersect_rect instead (it's more descriptive and faster): 

    collisions = args.geometry.find_all_intersect_rect args.state.player, args.state.terrain

    find_intersect_rect_quad_tree link

    This is a faster collision algorithm for determining if a rectangle intersects any rectangle in an array. In order to use find_intersect_rect_quad_tree, you must first generate a quad tree data structure using create_quad_tree. Use this function if find_intersect_rect isn't fast enough. 

    def tick args
  # create a player
  args.state.player ||= {
    x: 640 - 10,
    y: 360 - 10,
    w: 20,
    h: 20
  }

  # allow control of player movement using arrow keys
  args.state.player.x += args.inputs.left_right * 5
  args.state.player.y += args.inputs.up_down * 5

  # generate 40 random rectangles
  args.state.boxes ||= 40.map do
    {
      x: 1180 * rand + 50,
      y: 620 * rand + 50,
      w: 100,
      h: 100
    }
  end

  # generate a quad tree based off of rectangles.
  # the quad tree should only be generated once for
  # a given array of rectangles. if the rectangles
  # change, then the quad tree must be regenerated
  args.state.quad_tree ||= args.geometry.quad_tree_create args.state.boxes

  # use quad tree and find_intersect_rect_quad_tree to determine collision with player
  collision = args.geometry.find_intersect_rect_quad_tree args.state.player,
                                                          args.state.quad_tree

  # if there is a collision render a red box
  if collision
    args.outputs.solids << collision.merge(r: 255)
  end

  # render player as green
  args.outputs.solids << args.state.player.merge(g: 255)

  # render boxes as borders
  args.outputs.borders << args.state.boxes
end

    find_all_intersect_rect_quad_tree link

    This is a faster collision algorithm for determining if a rectangle intersects other rectangles in an array. In order to use find_all_intersect_rect_quad_tree, you must first generate a quad tree data structure using create_quad_tree. Use this function if find_all_intersect_rect isn't fast enough. 

    def tick args
  # create a player
  args.state.player ||= {
    x: 640 - 10,
    y: 360 - 10,
    w: 20,
    h: 20
  }

  # allow control of player movement using arrow keys
  args.state.player.x += args.inputs.left_right * 5
  args.state.player.y += args.inputs.up_down * 5

  # generate 40 random rectangles
  args.state.boxes ||= 40.map do
    {
      x: 1180 * rand + 50,
      y: 620 * rand + 50,
      w: 100,
      h: 100
    }
  end

  # generate a quad tree based off of rectangles.
  # the quad tree should only be generated once for
  # a given array of rectangles. if the rectangles
  # change, then the quad tree must be regenerated
  args.state.quad_tree ||= args.geometry.quad_tree_create args.state.boxes

  # use quad tree and find_intersect_rect_quad_tree to determine collision with player
  collisions = args.geometry.find_all_intersect_rect_quad_tree args.state.player,
                                                              args.state.quad_tree

  # if there is a collision render a red box
  args.outputs.solids << collisions.map { |c| c.merge(r: 255) }

  # render player as green
  args.outputs.solids << args.state.player.merge(g: 255)

  # render boxes as borders
  args.outputs.borders << args.state.boxes
end

    line_angle link

    Given a line, this function will return the angle of the line in degrees.

    vec2_dot_product link

    Given two Hashes with x and y keys (or Objects that respond to x and y), this function will return the dot product of the two vectors.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    vec2_normalize link

    Given a Hash with x and y keys (or an Object that responds to x and y), this function will return a Hash with x and y keys that represents the vector normalized.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    line_vec2 link

    Given a line, this function will return a Hash with x and y keys that represents the vector of the line.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    vec2_magnitude link

    Given a Hash with x and y keys (or an Object that responds to x and y), this function will return the magnitude of the vector.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    distance_squared link

    Given two Hashes with x and y keys (or Objects that respond to x and y), this function will return the distance squared between the two points. This is useful when you only want to compare distances, and don't need the actual distance.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    vec2_normal link

    Given a Hash with x and y keys (or an Object that responds to x and y), this function will return a Hash with x and y keys that represents the normal of the vector.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    circle_intersect_line? link

    The first parameters is a Hash with x, y, and radius keys (or an Object that responds to x, y, and radius).

    The second parameter is a Hash with x1, y1, x2, and y2 keys (or an Object that responds to x1, y1, x2, and y2).

    This function will return true if the circle intersects the line, and false if it does not.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    line_normal link

    The first parameter is a line (a Hash with x1, y1, x2, and y2 keys, or an Object that responds to x1, y1, x2, and y2).

    The second parameter is a Hash with x and y keys (or an Object that responds to x and y).

    This function will return a Hash with x and y keys that represents the normal of the line relative to the point provided.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    point_on_line? link

    The first parameter is a point (a Hash with x and y keys, or an Object that responds to x and y).

    The second parameter is a line (a Hash with x1, y1, x2, and y2 keys, or an Object that responds to x1, y1, x2, and y2).

    This function will return true if the point is on the line, and false if it is not.

    Note: Take a look at this sample app for a non-trivial example of how to use this function: ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/

    find_collisions link

    Given an Array of rects, returns a Hash of collisions. Each entry in the return Hash maps two rects from the input Array that intersect.

    Note that in the event of an intersection of rects A and B, the returned Hash will contain two entries: {A=>B,B=>A} 

    def tick(args)
  args.state.squares ||= []
  args.state.alphabet ||= ('A'..'Z').to_a

  # reset the squares if the user presses 'R'
  args.state.squares = [] if args.inputs.keyboard.r

  # add a new square every 4 ticks until we get to 26
  # the last part of the condition is to make sure we always have at least 1 square before
  # we start checking for collisions, otherwise #find_collisions will throw an error
  if (args.state.tick_count % 4 == 0 && args.state.squares.size < 26) || args.state.squares.size == 0

    # add a new square to the array with a random position, with some padding
    # so that the squares don't spawn too close to the edge of the screen
    # we also set the text to a random letter from the alphabet so we can re-use
    # the same hash for both the squares and their labels
    args.state.squares << {
      x: rand(1280 - 200) + 100, y: rand(720 - 300) + 100,
      w: 50, h: 50,
      text: args.state.alphabet[args.state.squares.size],
      alignment_enum: 1, # center the text
      r: 0, g: 255, b: 0, a: 128
    }
  end

  # check for collisions between the squares. this returns a hash of the
  # colliding squares, with the key being the first square and the value
  # being the second square
  collisions = args.geometry.find_collisions(args.state.squares)
  collisions.each do |key, value|
    key.merge!(r: 255, g: 0, b: 0)
    value.merge!(r: 0, g: 0, b: 255)
  end

  # render instructions and collision info
  args.outputs.labels << {x: 30, y: 20.from_top, text: "Press 'R' to reset" }
  args.outputs.labels << {x: 30, y: 45.from_top, text: "#{args.state.squares.size} squares, #{collisions.size} collisions" }
  args.outputs.labels << {x: 30, y: 70.from_top, text: "#{collisions.map { |k, v| "{#{k.text}=>#{v.text}}" }.join(', ')}" }

  # render the squares and their labels
  args.outputs.solids << args.state.squares
  args.outputs.labels << args.state.squares.map_with_index do |square, i|
    square.merge(
      x: square.x + 25, y: square.y + 35, # center the text in the square
      r: 0, g: 0, b: 0                    # make it black
    )
  end
end

    create_quad_tree link

    Generates a quad tree from an array of rectangles. See find_intersect_rect_quad_tree for usage.

    Audio (args.audio) link

    Hash that contains audio sources that are playing.

    Sounds that don't specify looping: true will be removed automatically from the hash after the playback ends. Looping sounds or sounds that should stop early must be removed manually.

    When you assign a hash to an audio output, a :length key will be added to the hash on the following tick. This will tell you the duration of the audio file in seconds (float).

    volume link

    You can globally control the volume for all audio using args.audio.volume. Example: 

    def tick args
  if args.inputs.down
    args.audio.volume -= 0.01
  elsif args.inputs.up
    args.audio.volume += 0.01
  end
end

    One-Time Sounds link

    Here's how to play audio one-time (does not loop). 

    def tick args
  # play a one-time non-looping sound every second
  if (args.state.tick_count % 60) == 0
    args.audio[:coin] = { input: "sounds/coin.wav" }
    # OR
    args.outputs.sounds << "sounds/coin.wav"
  end
end

    Looping Audio link

    Here's how to play audio that loops (eg background music), and how to stop the sound. 

    def tick args
  if args.state.tick_count == 0
    args.audio[:bg_music] = { input: "sounds/bg-music.ogg", looping: true }
  end

  # stop sound if space key is pressed
  if args.inputs.keyboard.key_down.space
    args.audio[:bg_music] = nil
    # OR
    args.audio.delete :bg_music
  end
end

    Setting Additional Audio Properties link

    Here are additional properties that can be set. 

    def tick args
  # The values below (except for input of course) are the default values that apply if you don't
  # specify the value in the hash.
  args.audio[:my_audio] ||= {
    input: 'sound/boom.wav',  # file path relative to mygame directory
    gain:    1.0,             # Volume (float value 0.0 to 1.0)
    pitch:   1.0,             # Pitch of the sound (1.0 = original pitch)
    paused:  false,           # Set to true to pause the sound at the current playback position
    looping: true,            # Set to true to loop the sound/music until you stop it
    foobar:  :baz,            # additional keys/values can be safely added to help with context/game logic (ie metadata)
    x: 0.0, y: 0.0, z: 0.0    # Relative position to the listener, x, y, z from -1.0 to 1.0
  }
end

    IMPORTANT: Please take note that gain and pitch must be given float values (eg gain: 1.0, not gain: 1 or game: 0).

    Advanced Audio Manipulation (Crossfade) link

    Take a look at the Audio Mixer sample app for a non-trival example of how to use these properties. The sample app is located within the DragonRuby zip file at ./samples/07_advanced_audio/01_audio_mixer.

    Here's an example of crossfading two bg music tracks. 

    def tick args
  # start bg-1.ogg at the start
  if args.state.tick_count == 0
    args.audio[:bg_music] = { input: "sounds/bg-1.ogg", looping: true, gain: 0.0 }
  end

  # if space is pressed cross fade to new bg music
  if args.inputs.keyboard.key_down.space
    # get the current bg music and create a new audio entry that represents the crossfade
    current_bg_music = args.audio[:bg_music]

    # cross fade audio entry
    args.audio[:bg_music_fade] = {
      input:    current_bg_music[:input],
      looping:  true,
      gain:     current_bg_music[:gain],
      pitch:    current_bg_music[:pitch],
      paused:   false,
      playtime: current_bg_music[:playtime]
    }

    # replace the current playing background music (toggling between bg-1.ogg and bg-2.ogg)
    # set the gain/volume to 0.0 (this will be increased to 1.0 accross ticks)
    new_background_music = { looping: true, gain: 0.0 }

    # determine track to play (swap between bg-1 and bg-2)
    new_background_music[:input] = if current_bg_music.input == "sounds/bg-1.ogg"
                                     "sounds/bg-2.ogg"
                                   else
                                     "sounds/bg-2.ogg"
                                   end

    # bg music audio entry
    args.audio[:bg_music] = new_background_music
  end

  # process cross fade (happens every tick)
  # increase the volume of bg_music every tick until it's at 100%
  if args.audio[:bg_music] && args.audio[:bg_music].gain < 1.0
    # increase the gain 1% every tick until we are at 100%
    args.audio[:bg_music].gain += 0.01
    # clamp value to 1.0 max value
    args.audio[:bg_music].gain = 1.0 if args.audio[:bg_music].gain > 1.0
  end

  # decrease the volume of cross fade bg music until it's 0.0, then delete it
  if args.audio[:bg_music_fade] && args.audio[:bg_music_fade].gain > 0.0
    # decrease by 1% every frame
    args.audio[:bg_music_fade].gain -= 0.01
    # delete audio when it's at 0%
    if args.audio[:bg_music_fade].gain <= 0.0
      args.audio[:bg_music_fade] = nil
    end
  end
end

    Audio encoding trouble shooting link

    If audio doesn't seem to be working, try re-encoding it via ffmpeg: 

    # re-encode ogg
ffmpeg -i ./mygame/sounds/SOUND.ogg -ac 2 -b:a 160k -ar 44100 -acodec libvorbis ./mygame/sounds/SOUND-converted.ogg

# convert wav to ogg
ffmpeg -i ./mygame/sounds/SOUND.wav -ac 2 -b:a 160k -ar 44100 -acodec libvorbis ./mygame/sounds/SOUND-converted.ogg

    Audio synthesis link

    Instead of a path to an audio file you can specify an array [channels, sample_rate, sound_source] for input to procedurally generate sound. You do this by providing an array of float values between -1.0 and 1.0 that describe the waveform you want to play.

    Sound source link

    A sound source can be one of two things:

    When you specify 2 for channels, then the generated sample array will be played back in an interleaved manner. The first element is the first sample for the left channel, the second element is the first sample for the right channel, the third element is the second sample for the left channel etc.

    Example: link

    def tick args
  sample_rate = 48000

  generate_sine_wave = lambda do
    frequency = 440.0 # A5
    samples_per_period = (sample_rate / frequency).ceil
    one_period = samples_per_period.map_with_index { |i|
      Math.sin((2 * Math::PI) * (i / samples_per_period))
    }
    one_period * frequency # Generate 1 second worth of sound
  end

  args.audio[:my_audio] ||= {
    input: [1, sample_rate, generate_sine_wave]
  }
end

    Easing (args.easing) link

    A set of functions that allow you to determine the current progression of an easing function.

    ease link

    This function will give you a float value between 0 and 1 that represents a percentage. You need to give the funcation a start_tick, current_tick, duration, and easing definitions.

    This YouTube video is a fantastic introduction to easing functions: https://www.youtube.com/watch?v=mr5xkf6zSzk

    Examples link

    This example shows how to fade in a label at frame 60 over two seconds (120 ticks). The :identity definition implies a linear fade: f(x) -> x. 

    def tick args
  fade_in_at   = 60
  current_tick = args.state.tick_count
  duration     = 120
  percentage   = args.easing.ease fade_in_at,
                                  current_tick,
                                  duration,
                                  :identity
  alpha = 255 * percentage
  args.outputs.labels << { x: 640,
                           y: 320, text: "#{percentage.to_sf}",
                           alignment_enum: 1,
                           a: alpha }
end

    This example will move a box at a linear speed from 0 to 1280. 

    def tick args
  start_time = 10
  duration = 60
  current_progress = args.easing.ease start_time,
                                      args.state.tick_count,
                                      duration,
                                      :identity
  args.outputs.solids << { x: 1280 * current_progress, y: 360, w: 10, h: 10 }
end

    Easing Definitions link

    There are a number of easing definitions availble to you:

    :identity

    The easing definition for :identity is f(x) = x. For example, if start_tick is 0, current_tick is 50, and duration is 100, then args.easing.ease 0, 50, 100, :identity will return 0.5 (since tick 50 is half way between 0 and 100).

    :flip

    The easing definition for :flip is f(x) = 1 - x. For example, if start_tick is 0, current_tick is 10, and duration is 100, then args.easing.ease 0, 10, 100, :flip will return 0.9 (since tick 10 means 100% - 10%).

    :quad, :cube, :quart, :quint

    These are the power easing definitions. :quad is f(x) = x * x (x squared), :cube is f(x) = x * x * x (x cubed), etc.

    The power easing definitions represent Smooth Start easing (the percentage changes slow at first and speeds up at the end).

    Example

    Here is an example of Smooth Start (the percentage changes slow at first and speeds up at the end). 

    def tick args
  start_tick   = 60
  current_tick = args.state.tick_count
  duration     = 120
  percentage   = args.easing.ease start_tick,
                                  current_tick,
                                  duration,
                                  :quad
  start_x      = 100
  end_x        = 1180
  distance_x   = end_x - start_x
  final_x      = start_x + (distance_x * percentage)

  start_y      = 100
  end_y        = 620
  distance_y   = end_y - start_y
  final_y      = start_y + (distance_y * percentage)

  args.outputs.labels << { x: final_x,
                           y: final_y,
                           text: "#{percentage.to_sf}",
                           alignment_enum: 1 }
end

    Combining Easing Definitions

    The base easing definitions can be combined to create common easing functions.

    Example

    Here is an example of Smooth Stop (the percentage changes fast at first and slows down at the end). 

    def tick args
  start_tick   = 60
  current_tick = args.state.tick_count
  duration     = 120

  # :flip, :quad, :flip is Smooth Stop
  percentage   = args.easing.ease start_tick,
                                  current_tick,
                                  duration,
                                  :flip, :quad, :flip
  start_x      = 100
  end_x        = 1180
  distance_x   = end_x - start_x
  final_x      = start_x + (distance_x * percentage)

  start_y      = 100
  end_y        = 620
  distance_y   = end_y - start_y
  final_y      = start_y + (distance_y * percentage)

  args.outputs.labels << { x: final_x,
                           y: final_y,
                           text: "#{percentage.to_sf}",
                           alignment_enum: 1 }
end

    Custom Easing Functions

    You can define your own easing functions by passing in a lambda as a definition or extending the Easing module.

    Example - Using Lambdas

    This easing function goes from 0 to 1 for the first half of the ease, then 1 to 0 for the second half of the ease. 

    def tick args
  fade_in_at    = 60
  current_tick  = args.state.tick_count
  duration      = 600
  easing_lambda = lambda do |percentage, start_tick, duration|
                    fx = percentage
                    if fx < 0.5
                      fx = percentage * 2
                    else
                      fx = 1 - (percentage - 0.5) * 2
                    end
                    fx
                  end

  percentage    = args.easing.ease fade_in_at,
                                   current_tick,
                                   duration,
                                   easing_lambda

  alpha = 255 * percentage
  args.outputs.labels << { x: 640,
                           y: 320,
                           a: alpha,
                           text: "#{percentage.to_sf}",
                           alignment_enum: 1 }
end
    Example - Extending Easing Definitions

    If you don't want to create a lambda, you can register an easing definition like so: 

    # 1. Extend the Easing module
module Easing
  def self.saw_tooth x
    if x < 0.5
      x * 2
    else
      1 - (x - 0.5) * 2
    end
  end
end

def tick args
  fade_in_at    = 60
  current_tick  = args.state.tick_count
  duration      = 600

  # 2. Reference easing definition by name
  percentage    = args.easing.ease fade_in_at,
                                   current_tick,
                                   duration,
                                   :saw_tooth

  alpha = 255 * percentage
  args.outputs.labels << { x: 640,
                           y: 320,
                           a: alpha,
                           text: "#{percentage.to_sf}",
                           alignment_enum: 1 }

end

    easing.ease_spline start_tick, current_tick, duration, spline link

    Given a start, current, duration, and a multiple bezier values, this function returns a number between 0 and 1 that represents the progress of an easing function.

    This example will move a box at a linear speed from 0 to 1280 and then back to 0 using two bezier definitions (represented as an array with four values). 

    def tick args
  start_time = 10
  duration = 60
  spline = [
    [  0, 0.25, 0.75, 1.0],
    [1.0, 0.75, 0.25,   0]
  ]
  current_progress = args.easing.ease_spline start_time,
                                             args.state.tick_count,
                                             duration,
                                             spline
  args.outputs.solids << { x: 1280 * current_progress, y: 360, w: 10, h: 10 }
end

    Pixel Arrays (args.pixel_arrays) link

    A PixelArray object with a width, height and an Array of pixels which are hexadecimal color values in ABGR format.

    You can create a pixel array like this: 

    w = 200
h = 100
args.pixel_array(:my_pixel_array).w = w
args.pixel_array(:my_pixel_array).h = h

    You'll also need to fill the pixels with values, if they are nil, the array will render with the checkerboard texture. You can use #00000000 to fill with transparent pixels if desired. 

    args.pixel_array(:my_pixel_array).pixels.fill #FF00FF00, 0, w * h

    Note: To convert from rgb hex (like skyblue #87CEEB) to abgr hex, you split it in pairs pair (eg 87 CE EB) and reverse the order (eg EB CE 87) add join them again: #EBCE87. Then add the alpha component in front ie: FF for full opacity: #FFEBCE87.

    You can draw it by using the symbol for :path 

    args.outputs.sprites << { x: 500, y: 300, w: 200, h: 100, path: :my_pixel_array) }

    If you want access a specific x, y position, you can do it like this for a bottom-left coordinate system: 

    x = 150
y = 33
args.pixel_array(:my_pixel_array).pixels[(height - y) * width + x] = 0xFFFFFFFF

    Related Sample Apps link

    CVars (args.cvars) link

    Hash contains metadata pulled from the files under the ./metadata directory. To get the keys that are available type $args.cvars.keys in the Console. Here is an example of how to retrieve the game version number: 

    def tick args
  args.outputs.labels << {
    x: 640,
    y: 360,
    text: args.cvars["game_metadata.version"].value.to_s
  }
end

    Each CVar has the following properties value, name, description, type, locked.

    Layout (args.layout) link

    Layout provides apis for placing primitives on a virtual grid that's within the "safe area" accross all platforms. This virtual grid is useful for rendering static controls (buttons, menu items, configuration screens, etc).

    For reference implementations, take a look at the following sample apps:

    The following example creates two menu items and updates a label with the button that was clicked: 

    def tick args
  # render debug_primitives of args.layout for help with placement
  # args.outputs.primitives << args.layout.debug_primitives

  # capture the location for a label centered at the top
  args.state.label_rect ||= args.layout.rect(row: 0, col: 10, w: 4, h: 1)
  # state variable to hold the current click status
  args.state.label_message ||= "click a menu item"

  # capture the location of two menu items positioned in the center
  # with a cell width of 4 and cell height of 2
  args.state.menu_item_1_rect ||= args.layout.rect(row: 1, col: 10, w: 4, h: 2)
  args.state.menu_item_2_rect ||= args.layout.rect(row: 3, col: 10, w: 4, h: 2)

  # render the label at the center of the label_rect
  args.outputs.labels << args.state.label_rect.center.merge(text: args.state.label_message,
                                                            anchor_x: 0.5,
                                                            anchor_y: 0.5)

  # render menu items
  args.outputs.sprites << args.state.menu_item_1_rect.merge(path: :solid,
                                                            r: 100,
                                                            g: 100,
                                                            b: 200)
  args.outputs.labels << args.state.menu_item_1_rect.center.merge(text: "item 1",
                                                                  r: 255,
                                                                  g: 255,
                                                                  b: 255,
                                                                  anchor_x: 0.5,
                                                                  anchor_y: 0.5)

  args.outputs.sprites << args.state.menu_item_2_rect.merge(path: :solid,
                                                            r: 100,
                                                            g: 100,
                                                            b: 200)
  args.outputs.labels << args.state.menu_item_2_rect.center.merge(text: "item 2",
                                                                  r: 255,
                                                                  g: 255,
                                                                  b: 255,
                                                                  anchor_x: 0.5,
                                                                  anchor_y: 0.5)

  # if click occurs, then determine which menu item was clicked
  if args.inputs.mouse.click
    if args.inputs.mouse.intersect_rect?(args.state.menu_item_1_rect)
      args.state.label_message = "menu item 1 clicked"
    elsif args.inputs.mouse.intersect_rect?(args.state.menu_item_2_rect)
      args.state.label_message = "menu item 2 clicked"
    else
      args.state.label_message = "click a menu item"
    end
  end
end

    rect link

    Given a row:, col:, w:, h:, returns a Hash with properties x, y, w, h, and center (which contains a Hash with x, y). The virtual grid is 12 rows by 24 columns (or 24 columns by 12 rows in portrait mode).

    debug_primitives link

    Function returns an array of primities that can be rendered to the screen to help you place items within the grid.

    Example: 

    def tick args
  args.outputs.primitives << args.layout.debug_primitives
end

    Array link

    The Array class has been extend to provide methods that will help in common game development tasks. Array is one of the most powerful classes in Ruby and a very fundamental component of Game Toolkit.

    map_2d link

    Assuming the array is an array of arrays, Given a block, each 2D array index invoked against the block. A 2D array is a common way to store data/layout for a stage. 

    repl do
  stage = [
    [:enemy, :empty, :player],
    [:empty, :empty,  :empty],
    [:enemy, :empty,  :enemy],
  ]

  occupied_tiles = stage.map_2d do |row, col, tile|
    if tile == :empty
      nil
    else
      [row, col, tile]
    end
  end.reject_nil

  puts "Stage:"
  puts stage

  puts "Occupied Tiles"
  puts occupied_tiles
end

    include_any? link

    Given a collection of items, the function will return true if any of self's items exists in the collection of items passed in:

    any_intersect_rect? link

    Assuming the array contains objects that respond to left, right, top, bottom, this method returns true if any of the elements within the array intersect the object being passed in. You are given an optional parameter called tolerance which informs how close to the other rectangles the elements need to be for it to be considered intersecting.

    The default tolerance is set to 0.1, which means that the primitives are not considered intersecting unless they are overlapping by more than 0.1. 

    repl do
  # Here is a player class that has position and implement
  # the ~attr_rect~ contract.
  class Player
    attr_rect
    attr_accessor :x, :y, :w, :h

    def initialize x, y, w, h
      @x = x
      @y = y
      @w = w
      @h = h
    end

    def serialize
      { x: @x, y: @y, w: @w, h: @h }
    end

    def inspect
      "#{serialize}"
    end

    def to_s
      "#{serialize}"
    end
  end

  # Here is a definition of two walls.
  walls = [
     [10, 10, 10, 10],
     { x: 20, y: 20, w: 10, h: 10 },
   ]

  # Display the walls.
  puts "Walls."
  puts walls
  puts ""

  # Check any_intersect_rect? on player
  player = Player.new 30, 20, 10, 10
  puts "Is Player #{player} touching wall?"
  puts (walls.any_intersect_rect? player)
  # => false
  # The value is false because of the default tolerance is 0.1.
  # The overlap of the player rect and any of the wall rects is
  # less than 0.1 (for those that intersect).
  puts ""

  player = Player.new 9, 10, 10, 10
  puts "Is Player #{player} touching wall?"
  puts (walls.any_intersect_rect? player)
  # => true
  puts ""
end

    map link

    The function given a block returns a new Enumerable of values.

    Example of using Array#map in conjunction with args.state and args.outputs.sprites to render sprites to the screen. 

    def tick args
  # define the colors of the rainbow in ~args.state~
  # as an ~Array~ of ~Hash~es with :order and :name.
  # :order will be used to determine render location
  #  and :name will be used to determine sprite path.
  args.state.rainbow_colors ||= [
    { order: 0, name: :red    },
    { order: 1, name: :orange },
    { order: 2, name: :yellow },
    { order: 3, name: :green  },
    { order: 4, name: :blue   },
    { order: 5, name: :indigo },
    { order: 6, name: :violet },
  ]

  # render sprites diagonally to the screen
  # with a width and height of 50.
  args.outputs
      .sprites << args.state
                      .rainbow_colors
                      .map do |color| # <-- ~Array#map~ usage
                        [
                          color[:order] * 50,
                          color[:order] * 50,
                          50,
                          50,
                          "sprites/square-#{color[:name]}.png"
                        ]
                      end
end

    each link

    The function, given a block, invokes the block for each item in the Array. Array#each is synonymous to foreach constructs in other languages.

    Example of using Array#each in conjunction with args.state and args.outputs.sprites to render sprites to the screen: 

    def tick args
  # define the colors of the rainbow in ~args.state~
  # as an ~Array~ of ~Hash~es with :order and :name.
  # :order will be used to determine render location
  #  and :name will be used to determine sprite path.
  args.state.rainbow_colors ||= [
    { order: 0, name: :red    },
    { order: 1, name: :orange },
    { order: 2, name: :yellow },
    { order: 3, name: :green  },
    { order: 4, name: :blue   },
    { order: 5, name: :indigo },
    { order: 6, name: :violet },
  ]

  # render sprites diagonally to the screen
  # with a width and height of 50.
  args.state
      .rainbow_colors
      .map do |color| # <-- ~Array#each~ usage
        args.outputs.sprites << [
          color[:order] * 50,
          color[:order] * 50,
          50,
          50,
          "sprites/square-#{color[:name]}.png"
        ]
      end
end

    reject_nil link

    Returns an Enumerable rejecting items that are nil, this is an alias for Array#compact: 

    repl do
  a = [1, nil, 4, false, :a]
  puts a.reject_nil
  # => [1, 4, false, :a]
  puts a.compact
  # => [1, 4, false, :a]
end

    reject_false link

    Returns an `Enumerable` rejecting items that are `nil` or `false`. 

    repl do
  a = [1, nil, 4, false, :a]
  puts a.reject_false
  # => [1, 4, :a]
end

    product link

    Returns all combinations of values between two arrays.

    Here are some examples of using product. Paste the following code at the bottom of main.rb and save the file to see the results: 

    repl do
  a = [0, 1]
  puts a.product
  # => [[0, 0], [0, 1], [1, 0], [1, 1]]
end

    repl do
  a = [ 0,  1]
  b = [:a, :b]
  puts a.product b
  # => [[0, :a], [0, :b], [1, :a], [1, :b]]
end

    Numeric link

    The Numeric class has been extend to provide methods that will help in common game development tasks.

    frame_index link

    This function is helpful for determining the index of frame-by-frame sprite animation. The numeric value self represents the moment the animation started.

    frame_index takes three additional parameters:

    frame_index will return nil if the time for the animation is out of bounds of the parameter specification.

    Example using variables: 

    def tick args
  start_looping_at = 0
  number_of_sprites = 6
  number_of_frames_to_show_each_sprite = 4
  does_sprite_loop = true

  sprite_index =
    start_looping_at.frame_index number_of_sprites,
                                 number_of_frames_to_show_each_sprite,
                                 does_sprite_loop

  sprite_index ||= 0

  args.outputs.sprites << [
    640 - 50,
    360 - 50,
    100,
    100,
    "sprites/dragon-#{sprite_index}.png"
  ]
end

    Example using named parameters. The named parameters version allows you to also specify a repeat_index which is useful if your animation has starting frames that shouldn't be considered when looped: 

    def tick args
  start_looping_at = 0

  sprite_index =
    start_looping_at.frame_index count: 6,
                                 hold_for: 4,
                                 repeat: true,
                                 repeat_index: 0,
                                 tick_count_override: args.state.tick_count

  sprite_index ||= 0

  args.outputs.sprites << [
    640 - 50,
    360 - 50,
    100,
    100,
    "sprites/dragon-#{sprite_index}.png"
  ]
end

    The named parameter variant of frame_index is also available on Numeric: 

    def tick args
  sprite_index =
    Numeric.frame_index start_at: 0,
                        count: 6,
                        hold_for: 4,
                        repeat: true,
                        repeat_index: 0,
                        tick_count_override: args.state.tick_count

  sprite_index ||= 0

  args.outputs.sprites << [
    640 - 50,
    360 - 50,
    100,
    100,
    "sprites/dragon-#{sprite_index}.png"
  ]
end

    elapsed_time link

    For a given number, the elapsed frames since that number is returned. `Kernel.tick_count` is used to determine how many frames have elapsed. An optional numeric argument can be passed in which will be used instead of `Kernel.tick_count`.

    Here is an example of how elapsed_time can be used. 

    def tick args
  args.state.last_click_at ||= 0

  # record when a mouse click occurs
  if args.inputs.mouse.click
    args.state.last_click_at = args.state.tick_count
  end

  # Use Numeric#elapsed_time to determine how long it's been
  if args.state.last_click_at.elapsed_time > 120
    args.outputs.labels << [10, 710, "It has been over 2 seconds since the mouse was clicked."]
  end
end

    And here is an example where the override parameter is passed in: 

    def tick args
  args.state.last_click_at ||= 0

  # create a state variable that tracks time at half the speed of args.state.tick_count
  args.state.simulation_tick = args.state.tick_count.idiv 2

  # record when a mouse click occurs
  if args.inputs.mouse.click
    args.state.last_click_at = args.state.simulation_tick
  end

  # Use Numeric#elapsed_time to determine how long it's been
  if (args.state.last_click_at.elapsed_time args.state.simulation_tick) > 120
    args.outputs.labels << [10, 710, "It has been over 4 seconds since the mouse was clicked."]
  end
end

    elapsed? link

    Returns true if Numeric#elapsed_time is greater than the number. An optional parameter can be passed into elapsed? which is added to the number before evaluating whether elapsed? is true.

    Example usage (no optional parameter): 

    def tick args
  args.state.box_queue ||= []

  if args.state.box_queue.empty?
    args.state.box_queue << { name: :red,
                              destroy_at: args.state.tick_count + 60 }
    args.state.box_queue << { name: :green,
                              destroy_at: args.state.tick_count + 60 }
    args.state.box_queue << { name: :blue,
                              destroy_at: args.state.tick_count + 120 }
  end

  boxes_to_destroy = args.state
                         .box_queue
                         .find_all { |b| b[:destroy_at].elapsed? }

  if !boxes_to_destroy.empty?
    puts "boxes to destroy count: #{boxes_to_destroy.length}"
  end

  boxes_to_destroy.each { |b| puts "box #{b} was elapsed? on #{args.state.tick_count}." }

  args.state.box_queue -= boxes_to_destroy
end

    Example usage (with optional parameter): 

    def tick args
  args.state.box_queue ||= []

  if args.state.box_queue.empty?
    args.state.box_queue << { name: :red,
                              create_at: args.state.tick_count + 120,
                              lifespan: 60 }
    args.state.box_queue << { name: :green,
                              create_at: args.state.tick_count + 120,
                              lifespan: 60 }
    args.state.box_queue << { name: :blue,
                              create_at: args.state.tick_count + 120,
                              lifespan: 120 }
  end

  # lifespan is passed in as a parameter to ~elapsed?~
  boxes_to_destroy = args.state
                         .box_queue
                         .find_all { |b| b[:create_at].elapsed? b[:lifespan] }

  if !boxes_to_destroy.empty?
    puts "boxes to destroy count: #{boxes_to_destroy.length}"
  end

  boxes_to_destroy.each { |b| puts "box #{b} was elapsed? on #{args.state.tick_count}." }

  args.state.box_queue -= boxes_to_destroy
end

    new? link

    Returns true if Numeric#elapsed_time == 0. Essentially communicating that number is equal to the current frame.

    Example usage: 

    def tick args
  args.state.box_queue ||= []

  if args.state.box_queue.empty?
    args.state.box_queue << { name: :red,
                              create_at: args.state.tick_count + 60 }
  end

  boxes_to_spawn_this_frame = args.state
                                  .box_queue
                                  .find_all { |b| b[:create_at].new? }

  boxes_to_spawn_this_frame.each { |b| puts "box #{b} was new? on #{args.state.tick_count}." }

  args.state.box_queue -= boxes_to_spawn_this_frame
end

    Kernel link

    Kernel in the DragonRuby Runtime has patches for how standard out is handled and also contains a unit of time in games called a tick.

    tick_count link

    Returns the current tick of the game. This value is reset if you call $gtk.reset.

    global_tick_count link

    Returns the current tick of the application from the point it was started. This value is never reset.

    Grid (args.grid) link

    Returns the virtual grid for the game.

    name link

    Returns either :origin_bottom_left or :origin_center.

    bottom link

    Returns the y value that represents the bottom of the grid.

    top link

    Returns the y value that represents the top of the grid.

    left link

    Returns the x value that represents the left of the grid.

    right link

    Returns the x value that represents the right of the grid.

    rect link

    Returns a rectangle Primitive that represents the grid.

    origin_bottom_left! link

    Change the grids coordinate system to 0, 0 at the bottom left corner.

    origin_center! link

    Change the grids coordinate system to 0, 0 at the center of the screen.

    orientation link

    Returns either :portrait or :landscape. The orientation of your game is set within ./mygame/metadata/game_metadata.txt.

    w link

    Returns the grid's width (value is 1280 if orientation :landscape, and 720 if orientation is :portrait).

    h link

    Returns the grid's width (value is 720 if orientation :landscape, and 1280 if orientation is :portrait).

    Grid HD Properties link

    The following properties are available to Pro license holders. Setting hd=true and hd=true in ./mygame/metadata/game_metadata.txt will enable All Screen Mode.

    Please review the sample app located at ./samples/07_advanced_rendering_hd/03_allscreen_properties.

    When All Screen mode is enabled, you can render outside of the 1280x720 safe area. The 1280x720 logical canvas will be centered within the screen and scaled to one of the following closest/bess-fit resolutions.

    Regardless of the rendering resolution, your logical canvas will always be 1280x720 and all hd_* values will be at this same logical scale.

    hd_left link

    Returns the position of the left edge of the screen at the logical scale of 1280x720. For example, if the window's width is 1290x720, then hd_left will be -5.

    hd_right link

    Returns the position of the right edge of the screen at the logical scale of 1280x720. For example, if the window's width is 1290x720, then hd_right will be 1285.

    hd_bottom link

    Returns the position of the bottom edge of the screen at the logical scale of 1280x720. For example, if the window's width is 1280x730, then hd_bottom will be -5.

    hd_top link

    Returns the position of the top edge of the screen at the logical scale of 1280x720. For example, if the window's width is 1280x730, then hd_top will be 725.

    hd_offset_x link

    Returns the number of pixels that the 1280x720 canvas is offset from the left so that it's centered in the screen.

    hd_offset_y link

    Returns the number of pixels that the 1280x720 canvas is offset from the bottom so that it's centered in the screen.

    window_width link

    Returns the true width of the window. High DPI settings are not taken into consideration.

    window_height link

    Returns the true height of the window. High DPI settings are not taken into consideration.

    native_width link

    Returns the true width of the window. High DPI settings (macOS, iOS, Android) are taken into consideration.

    native_height link

    Returns the true height of the window. High DPI settings (macOS, iOS, Android) are taken into consideration.

    native_scale link

    Returns a decimal value representing the rendering scale of the game.

    native_scale_enum link

    Returns an integer value representing the rendering scale of the game.

    The enum value is taken into consideration when rendering a sprite through texture atlases.

    Given the following code: 

    def tick args
  args.outputs.sprites << { x: 0, y: 0, w: 100, h: 100, path: "sprites/player.png" }
end

    The sprite path of sprites/player.png will be replaced according to the following naming conventions (fallback to a lower resolution is automatically handled if a sprite with naming convention isn't found):

    Samples link

    Follows is a source code listing for all files that have been open sourced. This code can be found in the ./samples directory.

    Learn Ruby Optional link

    Beginner Ruby Primer - automation.rb link

    # ./samples/00_learn_ruby_optional/00_beginner_ruby_primer/app/automation.rb
# ==========================================================================
#  _    _ ________     __  _      _____  _____ _______ ______ _   _ _ _ _ _
# | |  | |  ____\ \   / / | |    |_   _|/ ____|__   __|  ____| \ | | | | | |
# | |__| | |__   \ \_/ /  | |      | | | (___    | |  | |__  |  \| | | | | |
# |  __  |  __|   \   /   | |      | |  \___ \   | |  |  __| | . ` | | | | |
# | |  | | |____   | |    | |____ _| |_ ____) |  | |  | |____| |\  |_|_|_|_|
# |_|  |_|______|  |_|    |______|_____|_____/   |_|  |______|_| \_(_|_|_|_)
#
#
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                \  |  /
#                                 \ | /
#                                   +
#
# If you are new to the programming language Ruby, then you may find the
# following code a bit overwhelming. Come back to this file when you have
# a better grasp of Ruby and Game Toolkit.
#
# What follows is an automations script # that can be run via terminal:
# ./samples/00_beginner_ruby_primer $ ../../dragonruby . --eval app/automation.rb
# ==========================================================================

$gtk.reset
$gtk.scheduled_callbacks.clear
$gtk.schedule_callback 10 do
  $gtk.console.set_command 'puts "Hello DragonRuby!"'
end

$gtk.schedule_callback 20 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 30 do
  $gtk.console.set_command 'outputs.solids << [910, 200, 100, 100, 255, 0, 0]'
end

$gtk.schedule_callback 40 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 50 do
  $gtk.console.set_command 'outputs.solids << [1010, 200, 100, 100, 0, 0, 255]'
end

$gtk.schedule_callback 60 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 70 do
  $gtk.console.set_command 'outputs.sprites << [1110, 200, 100, 100, "sprites/dragon_fly_0.png"]'
end

$gtk.schedule_callback 80 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 90 do
  $gtk.console.set_command "outputs.labels << [1210, 200, state.tick_count, 0, 255, 0]"
end

$gtk.schedule_callback 100 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 110 do
  $gtk.console.set_command "state.sprite_frame = state.tick_count.idiv(4).mod(6)"
end

$gtk.schedule_callback 120 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 130 do
  $gtk.console.set_command "outputs.labels << [1210, 170, state.sprite_frame, 0, 255, 0]"
end

$gtk.schedule_callback 140 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 150 do
  $gtk.console.set_command "state.sprite_path =  \"sprites/dragon_fly_\#{state.sprite_frame}.png\""
end

$gtk.schedule_callback 160 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 170 do
  $gtk.console.set_command "outputs.labels    << [910, 330, \"path: \#{state.sprite_path}\", 0, 255, 0]"
end

$gtk.schedule_callback 180 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 190 do
  $gtk.console.set_command "outputs.sprites   << [910, 330, 370, 370, state.sprite_path]"
end

$gtk.schedule_callback 200 do
  $gtk.console.eval_the_set_command
end

$gtk.schedule_callback 300 do
  $gtk.console.set_command ":wq"
end

$gtk.schedule_callback 400 do
  $gtk.console.eval_the_set_command
end

    Beginner Ruby Primer - main.rb link

    # ./samples/00_learn_ruby_optional/00_beginner_ruby_primer/app/main.rb
# ==========================================================================
#  _    _ ________     __  _      _____  _____ _______ ______ _   _ _ _ _ _
# | |  | |  ____\ \   / / | |    |_   _|/ ____|__   __|  ____| \ | | | | | |
# | |__| | |__   \ \_/ /  | |      | | | (___    | |  | |__  |  \| | | | | |
# |  __  |  __|   \   /   | |      | |  \___ \   | |  |  __| | . ` | | | | |
# | |  | | |____   | |    | |____ _| |_ ____) |  | |  | |____| |\  |_|_|_|_|
# |_|  |_|______|  |_|    |______|_____|_____/   |_|  |______|_| \_(_|_|_|_)
#
#
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                   |
#                                \  |  /
#                                 \ | /
#                                   +
#
# If you are new to the programming language Ruby, then you may find the
# following code a bit overwhelming. This sample is only designed to be
# run interactively (as opposed to being manipulated via source code).
#
# Start up this sample and follow along by visiting:
# https://s3.amazonaws.com/s3.dragonruby.org/dragonruby-gtk-primer.mp4
#
# It is STRONGLY recommended that you work through all the samples before
# looking at the code in this file.
# ==========================================================================

class TutorialOutputs
  attr_accessor :solids, :sprites, :labels, :lines, :borders

  def initialize
    @solids  = []
    @sprites = []
    @labels  = []
    @lines   = []
    @borders = []
  end

  def tick
    @solids  ||= []
    @sprites ||= []
    @labels  ||= []
    @lines   ||= []
    @borders ||= []
    @solids.each  { |p| $gtk.args.outputs.reserved << p.solid  }
    @sprites.each { |p| $gtk.args.outputs.reserved << p.sprite }
    @labels.each  { |p| $gtk.args.outputs.reserved << p.label  }
    @lines.each   { |p| $gtk.args.outputs.reserved << p.line   }
    @borders.each { |p| $gtk.args.outputs.reserved << p.border }
  end

  def clear
    @solids.clear
    @sprites.clear
    @labels.clear
    @borders.clear
  end
end

def defaults
  state.reset_button ||=
    state.new_entity(
      :button,
      label:  [1190, 68, "RESTART", -2, 0, 0, 0, 0].label,
      background: [1160, 38, 120, 50, 255, 255, 255].solid
    )
  $gtk.log_level = :off
end

def tick_reset_button
  return unless state.hello_dragonruby_confirmed
  $gtk.args.outputs.reserved << state.reset_button.background
  $gtk.args.outputs.reserved << state.reset_button.label
  if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.reset_button.background)
    restart_tutorial
  end
end

def seperator
  @seperator = "=" * 80
end

def tick_intro
  queue_message "Welcome to the DragonRuby GTK primer! Try typing the
code below and press ENTER:

    puts \"Hello DragonRuby!\"
"
end

def tick_hello_dragonruby
  return unless console_has? "Hello DragonRuby!", "puts "

  $gtk.args.state.hello_dragonruby_confirmed = true

  queue_message "Well HELLO to you too!

If you ever want to RESTART the tutorial, just click the \"RESTART\"
button in the bottom right-hand corner.

Let's continue shall we? Type the code below and press ENTER:

    outputs.solids << [910, 200, 100, 100, 255, 0, 0]
"

end

def tick_explain_solid
  return unless $tutorial_outputs.solids.any? {|s| s == [910, 200, 100, 100, 255, 0, 0]}

  queue_message "Sweet!

The code: outputs.solids << [910, 200, 100, 100, 255, 0, 0]
Does the following:
1. GET the place where SOLIDS go: outputs.solids
2. Request that a new SOLID be ADDED: <<
3. The DEFINITION of a SOLID is the ARRAY:
   [910, 200, 100, 100, 255, 0, 0]

      GET       ADD     X      Y    WIDTH  HEIGHT RED  GREEN  BLUE
       |         |      |      |      |      |     |     |     |
       |         |      |      |      |      |     |     |     |
outputs.solids  <<    [910,   200,   100,   100,  255,   0,    0]
                      |_________________________________________|
                                           |
                                           |
                                         ARRAY

Now let's create a blue SOLID. Type:

    outputs.solids << [1010, 200, 100, 100, 0, 0, 255]
"

  state.explain_solid_confirmed = true
end

def tick_explain_solid_blue
  return unless state.explain_solid_confirmed
  return unless $tutorial_outputs.solids.any? {|s| s == [1010, 200, 100, 100, 0, 0, 255]}
  state.explain_solid_blue_confirmed = true

  queue_message "And there is our blue SOLID!

The ARRAY is the MOST important thing in DragonRuby GTK.

Let's create a SPRITE using an ARRAY:

  outputs.sprites << [1110, 200, 100, 100, 'sprites/dragon_fly_0.png']
"
end

def tick_explain_tick_count
  return unless $tutorial_outputs.sprites.any? {|s| s == [1110, 200, 100, 100, 'sprites/dragon_fly_0.png']}
  return if $tutorial_outputs.labels.any? {|l| l == [1210, 200, state.tick_count, 255, 255, 255]}
  state.explain_tick_count_confirmed = true

  queue_message "Look at the cute little dragon!

We can create a LABEL with ARRAYS too. Let's create a LABEL showing
THE PASSAGE OF TIME, which is called TICK_COUNT.

  outputs.labels << [1210, 200, state.tick_count, 0, 255, 0]
"
end

def tick_explain_mod
  return unless $tutorial_outputs.labels.any? {|l| l == [1210, 200, state.tick_count, 0, 255, 0]}
  state.explain_mod_confirmed = true
  queue_message "
The code: outputs.labels << [1210, 200, state.tick_count, 0, 255, 0]
Does the following:
1. GET the place where labels go: outputs.labels
2. Request that a new label be ADDED: <<
3. The DEFINITION of a LABEL is the ARRAY:
   [1210, 200, state.tick_count, 0, 255, 0]

      GET       ADD     X      Y          TEXT         RED  GREEN  BLUE
       |         |      |      |            |           |     |     |
       |         |      |      |            |           |     |     |
outputs.labels  <<    [1210,  200,   state.tick_count,  0,   255,   0]
                      |______________________________________________|
                                              |
                                              |
                                            ARRAY

Now let's do some MATH, save the result to STATE, and create a LABEL:

    state.sprite_frame = state.tick_count.idiv(4).mod(6)
    outputs.labels << [1210, 170, state.sprite_frame, 0, 255, 0]

Type the lines above (pressing ENTER after each line).
"
end

def tick_explain_string_interpolation
  return unless state.explain_mod_confirmed
  return unless state.sprite_frame == state.tick_count.idiv(4).mod(6)
  return unless $tutorial_outputs.labels.any? {|l| l == [1210, 170, state.sprite_frame, 0, 255, 0]}

  queue_message "Here is what the mathematical computation you just typed does:

1. Create an item of STATE named SPRITE_FRAME: state.sprite_frame =
2. Set this SPRITE_FRAME to the PASSAGE OF TIME (tick_count),
   DIVIDED EVENLY (idiv) into 4,
   and then compute the REMAINDER (mod) of 6.

   STATE   SPRITE_FRAME    PASSAGE OF      HOW LONG   HOW MANY
     |          |             TIME         TO SHOW    IMAGES
     |          |              |           AN IMAGE   TO FLIP THROUGH
     |          |              |               |      |
state.sprite_frame =     state.tick_count.idiv(4).mod(6)
                                           |       |
                                           |       +- REMAINDER OF DIVIDE
                                    DIVIDE EVENLY
                                    (NO DECIMALS)

With the information above, we can animate a SPRITE
using STRING INTERPOLATION: \#{}
which creates a unique SPRITE_PATH:

  state.sprite_path =  \"sprites/dragon_fly_\#{state.sprite_frame}.png\"
  outputs.labels    << [910, 330, \"path: \#{state.sprite_path}\", 0, 255, 0]
  outputs.sprites   << [910, 330, 370, 370, state.sprite_path]

Type the lines above (pressing ENTER after each line).
"
end

def tick_reprint_on_error
  return unless console.last_command_errored
  puts $gtk.state.messages.last
  puts "\nWhoops! Try again."
  console.last_command_errored = false
end

def tick_evals
  state.evals ||= []
  if console.last_command && (console.last_command.start_with?("outputs.") || console.last_command.start_with?("state."))
    state.evals << console.last_command
    console.last_command = nil
  end

  state.evals.each do |l|
    Kernel.eval l
  end
rescue Exception => e
  state.evals = state.evals[0..-2]
end

$tutorial_outputs ||= TutorialOutputs.new

def tick args
  $gtk.log_level = :off
  defaults
  console.show
  $tutorial_outputs.clear
  $tutorial_outputs.solids  << [900, 37, 480, 700,   0,   0,   0, 255]
  $tutorial_outputs.borders << [900, 37, 380, 683, 255, 255, 255]
  tick_evals
  $tutorial_outputs.tick
  tick_intro
  tick_hello_dragonruby
  tick_reset_button
  tick_explain_solid
  tick_explain_solid_blue
  tick_reprint_on_error
  tick_explain_tick_count
  tick_explain_mod
  tick_explain_string_interpolation
end

def console
  $gtk.console
end

def queue_message message
  $gtk.args.state.messages ||= []
  return if $gtk.args.state.messages.include? message
  $gtk.args.state.messages << message
  last_three = [$gtk.console.log[-3], $gtk.console.log[-2], $gtk.console.log[-1]].reject_nil
  $gtk.console.log.clear
  puts seperator
  $gtk.console.log += last_three
  puts seperator
  puts message
  puts seperator
end

def console_has? message, not_message = nil
  console.log
         .map(&:upcase)
         .reject { |s| not_message && s.include?(not_message.upcase) }
         .any?   { |s| s.include?("#{message.upcase}") }
end

def restart_tutorial
  $tutorial_outputs.clear
  $gtk.console.log.clear
  $gtk.reset
  puts "Starting the tutorial over!"
end

def state
  $gtk.args.state
end

def inputs
  $gtk.args.inputs
end

def outputs
  $tutorial_outputs
end

    Intermediate Ruby Primer - printing.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/01_printing.txt
# ====================================================================================
# Commenting Code
# ====================================================================================
#
# Prefixing text with a pound sign (#) is how you comment code in Ruby. Example:
#
# I am commented code. And so are the lines above.
#
# I you want more than a quick primer on Ruby, check out https://poignant.guide/. It's
# an entertaining read. Otherwise, go to the next txt file.
#
# Follow along by visiting:
# https://s3.amazonaws.com/s3.dragonruby.org/dragonruby-gtk-intermediate.mp4

# ====================================================================================
#  Printing to the Console:
# ====================================================================================
#
# Every time you save repl.rb file, DragonRuby runs the code within it. Copy this text
# to repl.rb and save to see Hello World printed to the console.

repl do
  puts '* RUBY PRIMER: Printing to the console using the ~puts~ function.'
  puts '===='
  puts '======'
  puts '================================'
  puts 'Hello World'
  puts '================================'
  puts '======'
  puts '===='
end

    Intermediate Ruby Primer - strings.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/02_strings.txt
# ====================================================================================
#  Strings
# ====================================================================================
#
# Here is how you work with strings in Ruby. Take the text
# in this file and paste it into repl.rb and save:

repl do
  puts '* RUBY PRIMER: strings'
  message = "Hello World"
  puts "The value of message is: " + message
  puts "Any value can be interpolated within a string using \#{}."
  puts "Interpolated message: #{message}."
  puts 'This #{message} is not interpolated because the string uses single quotes.'
end

    Intermediate Ruby Primer - numbers.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/03_numbers.txt
# ====================================================================================
#  Numerics
# ====================================================================================
#
# Here is how you work with numbers in Ruby. Take the text
# in this file and paste it into repl.rb and save:

repl do
  puts '* RUBY PRIMER: Fixnum and Floats'
  a = 10
  puts "The value of a is: #{a}"
  puts "a + 1 is: #{a + 1}"
  puts "a / 3 is: #{a / 3}"
  puts ''

  b = 10.12
  puts "The value of b is: #{b}"
  puts "b + 1 is: #{b + 1}"
  puts "b as an integer is: #{b.to_i}"
  puts ''
end

    Intermediate Ruby Primer - booleans.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/04_booleans.txt
# ====================================================================================
#  Booleans
# ====================================================================================
#
# Here is how you work with numbers in Ruby. Take the text
# in this file and paste it into repl.rb and save:

repl do
  puts '* RUBY PRIMER: TrueClass, FalseClass, NilClass (truthy / falsey values)'
  puts "Anything that *isn't* false or nil is true."

  c = 30
  puts "The value of c is #{c}."

  if c
    puts "This if statement ran because c is truthy."
  end

  d = false
  puts "The value if d is #{d}. The type for d is #{d.class}."

  if !d
    puts "This if statement ran because d is falsey, using the not operator (!)."
  end

  e = nil
  puts "Nil is also considered falsey. The value of e is: #{e} (a blank string when printed). Which is of type #{e.class}."

  if !e
    puts "This if statement ran because e is nil and the if statement applied the NOT operator. !e yields a type of #{(!e).class}."
  end
end

    Intermediate Ruby Primer - conditionals.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/05_conditionals.txt
# ====================================================================================
#  Conditionals
# ====================================================================================
#
# Here is how you create conditionals in Ruby. Take the text
# in this file and paste it into repl.rb and save:

repl do
  puts "* RUBY PRIMER: Conditionals"
end

# ====================================================================================
#  if
# ====================================================================================

repl do
  puts "** INFO: if statement"
  i_am_one = 1
  if i_am_one
    puts "This was printed because i_am_one is truthy."
  end
end

# ====================================================================================
#  if/else
# ====================================================================================

repl do
  puts "** INFO: if/else statement"
  i_am_false = false
  if i_am_false
    puts "This will NOT get printed because i_am_false is false."
  else
    puts "This was printed because i_am_false is false."
  end
end


# ====================================================================================
#  if/elsif/else
# ====================================================================================

repl do
  puts "** INFO: if/elsif/else statement"
  i_am_false = false
  i_am_true  = true
  if i_am_false
    puts "This will NOT get printed because i_am_false is false."
  elsif i_am_true
    puts "This was printed because i_am_true is true."
  else
    puts "This will NOT get printed i_am_true was true."
  end
end

# ====================================================================================
#  case
# ====================================================================================

repl do
  puts "** INFO case statement"
  i_am_one = 1 # change this value to see different results

  case i_am_one
  when 10
    puts "the value of i_am_one is 10"
  when 9
    puts "the value of i_am_one is 9"
  when 5
    puts "the value of i_am_one is 5"
  when 1
    puts "the value of i_am_one is 1"
  else
    puts "Value wasn't cased."
  end
end

# ====================================================================================
#  comparison operators
# ====================================================================================

repl do
  puts "** INFO: Different types of comparisons"
  if 4 == 4
    puts "4 equals 4 (==)"
  end

  if 4 != 3
    puts "4 does not equal 3 (!=)"
  end

  if 3 < 4
    puts "3 is less than 4 (<)"
  end

  if 4 > 3
    puts "4 is greater than 3 (>)"
  end
end

# ====================================================================================
#  and/or conditionals
# ====================================================================================

repl do
  puts "** INFO: AND, OR operator (&&, ||)"
  if (4 > 3) || (3 < 4) || false
    puts "print this if 4 is greater than 3 OR 3 is less than 4 OR false is true (||)"
  end

  if (4 > 3) && (3 < 4)
    puts "print this if 4 is greater than 3 AND 3 is less than 4 (&&)"
  end
end

    Intermediate Ruby Primer - looping.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/06_looping.txt
# ====================================================================================
#  Looping
# ====================================================================================
#
# Looping looks a whole lot different than other languages.
# But it's pretty awesome when you get used to it.

repl do
  puts "* RUBY PRIMER: Loops"
end

# ====================================================================================
#  times
# ====================================================================================

repl do
  puts "** INFO: ~Numeric#times~ (for loop)"
  3.times do |i|
    puts i
  end
end

# ====================================================================================
#  foreach
# ====================================================================================

repl do
  puts "** INFO: ~Array#each~ (for each loop)"
  array = ["a", "b", "c", "d"]
  array.each do |char|
    puts char
  end

  puts "** INFO: ~Array#each_with_index~ (for each loop)"
  array = ["a", "b", "c", "d"]
  array.each do |char, i|
    puts "index #{i}: #{char}"
  end
end

# ====================================================================================
#  ranges
# ====================================================================================

repl do
  puts "** INFO: range block exclusive (three dots)"
  (0...3).each do |i|
    puts i
  end

  puts "** INFO: range block inclusive (two dots)"
  (0..3).each do |i|
    puts i
  end
end

    Intermediate Ruby Primer - functions.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/07_functions.txt
# ====================================================================================
# Functions
# ====================================================================================

# The last statement of a function is implictly returned. Parenthesis for functions
# are optional as long as the statement can be envaluated disambiguously.

repl do
  puts "* RUBY PRIMER: Functions"
end

# ====================================================================================
# Functions single parameter
# ====================================================================================

repl do
  puts "* INFO: Function with one parameter"

  # function definition
  def add_one_to n
    n + 1
  end

  # Parenthesis are optional in Ruby as long as the
  # parsing is disambiguous. Here are a couple of variations.
  # Generally speaking, don't put parenthesis is you don't have to.

  # Conventional Usage of Parenthesis.
  puts add_one_to(3)

  # DragonRuby's recommended use of parenthesis (inner function has parenthesis).
  puts (add_one_to 3)

  # Full parens.
  puts(add_one_to(3))

  # Outer function has parenthesis
  puts(add_one_to 3)
end

# ====================================================================================
# Functions with default parameter values
# ====================================================================================

repl do
  puts "* INFO: Function with default value"
  def function_with_default_value v = 10
    v * 10
  end

  puts "Passing the argument three yields: #{function_with_default_value 3}"
  puts "Passing no argument yields: #{function_with_default_value}"
end

# ====================================================================================
# Nil default parameter value and ||= operator.
# ====================================================================================

repl do
  puts "* INFO: Using the OR EQUAL operator (||=)"
  def function_with_nil_default_with_local a = nil
    result   = a
    result ||= "DEFAULT_VALUE_OF_A_IS_NIL_OR_FALSE"
    "value is #{result}."
  end

  puts "Passing 'hi' as the argument yields: #{function_with_nil_default_with_local 'hi'}"
  puts "Passing nil: #{function_with_nil_default_with_local}"
end

    Intermediate Ruby Primer - arrays.txt link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/08_arrays.txt
# ====================================================================================
# Arrays
# ====================================================================================

# Arrays are incredibly powerful in Ruby. Learn to use them well.

repl do
  puts "* RUBY PRIMER: ARRAYS"
end

# ====================================================================================
# Enumerable ranges and .to_a
# ====================================================================================

repl do
  puts "** INFO: Create an array with the numbers 1 to 10."
  one_to_ten = (1..10).to_a
  puts one_to_ten
end

# ====================================================================================
# Finding elements
# ====================================================================================

repl do
  puts "** INFO: Finding elements in an array using ~Array#find_all~."
  puts "Create a new array that only contains even numbers from the previous array."

  one_to_ten = (1..10).to_a
  evens = one_to_ten.find_all do |number|
    number % 2 == 0
  end

  puts evens
end

# ====================================================================================
# Rejecting elements
# ====================================================================================

repl do
  puts "** INFO: Removing elements in an array using ~Array#reject~."
  puts "Create a new array that rejects odd numbers."

  one_to_ten = (1..10).to_a
  also_even = one_to_ten.reject do |number|
    number % 2 != 0
  end

  puts also_even
end

# ====================================================================================
# Array transform using the map function.
# ====================================================================================

repl do
  puts "** INFO: Creating new derived values from an array using ~Array#map~."
  puts "Create an array that doubles every number."

  one_to_ten = (1..10).to_a
  doubled = one_to_ten.map do |number|
    number * 2
  end

  puts doubled
end

# ====================================================================================
# Combining array functions.
# ====================================================================================

repl do
  puts "** INFO: Combining ~Array#find_all~ along with ~Array#map~."
  puts "Create an array that selects only odd numbers and then multiply those by 10."

  one_to_ten = (1..10).to_a
  odd_doubled = one_to_ten.find_all do |number|
    number % 2 != 0
  end.map do |odd_number|
    odd_number * 10
  end

  puts odd_doubled
end

# ====================================================================================
# Product function.
# ====================================================================================

repl do
  puts "** INFO: Create all combinations of array values using ~Array#product~."
  puts "All two-item pairs of numbers 1 to 10."
  one_to_ten = (1..10).to_a
  all_combinations = one_to_ten.product(one_to_ten)
  puts all_combinations
end

# ====================================================================================
# Uniq and sort function.
# ====================================================================================

repl do
  puts "** INFO: Providing uniq values using ~Array#uniq~ and ~Array#sort~."
  puts "All uniq combinations of numbers regardless of order."
  puts "For example: [1, 2] is the same as [2, 1]."
  one_to_ten = (1..10).to_a
  uniq_combinations =
    one_to_ten.product(one_to_ten)
              .map do |unsorted_number|
                unsorted_number.sort
              end.uniq
  puts uniq_combinations
end

# ====================================================================================
# Example of an advanced array transform.
# ====================================================================================

repl do
  puts "** INFO: Advanced chaining. Combining ~Array's ~map~, ~find_all~, ~sort~, and ~sort_by~."
  puts "All unique Pythagorean Triples between 1 and 100 sorted by area of the triangle."

  one_to_hundred = (1..100).to_a

  triples =
    one_to_hundred.product(one_to_hundred).map do |width, height|
                [width, height, Math.sqrt(width ** 2 + height ** 2)]
              end.find_all do |_, _, hypotenuse|
                hypotenuse.to_i == hypotenuse
              end.map do |triangle|
                triangle.map(&:to_i)
              end.uniq do |triangle|
                triangle.sort
              end.map do |width, height, hypotenuse|
                [width, height, hypotenuse, (width * height) / 2]
              end.sort_by do |_, _, _, area|
                area
              end

  triples.each do |width, height, hypotenuse, _|
    puts "(#{width}, #{height}, #{hypotenuse})"
  end
end

# ====================================================================================
# Example of an sorting.
# ====================================================================================

repl do
  puts "** INFO: Implementing a custom sort function that operates on the ~Hash~ datatype."

  things_to_sort = [
    { type: :background, order: 1 },
    { type: :foreground, order: 1 },
    { type: :foreground, order: 2 }
  ]
  puts "*** Original array."
  puts things_to_sort

  puts "*** Simple sort using key."
  # For a simple sort, you can use sort_by
  results = things_to_sort.sort_by do |hash|
    hash[:order]
  end

  puts results

  puts "*** Custom sort."
  puts "**** Sorting process."
  # for a more complicated sort, you can provide a block that returns
  # -1, 0, 1 for a left and right operand
  results = things_to_sort.sort do |l, r|
    sort_result = 0
    puts "here is l: #{l}"
    puts "here is r: #{r || "nil"}"
    # if either value is nil/false return 0
    if !l || !r
      sort_result = 0
    # if the type of "left" is background and the
    # type of "right" is foreground, then return
    # -1 (which means "left" is less than "right"
    elsif l[:type] == :background && r[:type] == :foreground
      sort_result = -1
    # if the type of "left" is foreground and the
    # type of "right" is background, then return
    #  1 (which means "left" is greater than "right"
    elsif l[:type] == :foreground && r[:type] == :background
      sort_result = 1
    # if "left" and "right"'s type are the same, then
    # use the order as the tie breaker
    elsif l[:order] < r[:order]
      sort_result = -1
    elsif l[:order] > r[:order]
      sort_result = 1
    # returning 0 means both values are equal
    else
      sort_result = 0
    end
    sort_result
  end.to_a

  puts "**** Sort result."
  puts results
end

# ====================================================================================
# Api documention for Array that is worth commiting to memory because arrays are so
# awesome in Ruby: https://docs.ruby-lang.org/en/2.0.0/Array.html
# ====================================================================================

    Intermediate Ruby Primer - main.rb link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/main.rb
def tick args
  args.outputs.labels << [640, 380, "Open repl.rb in the text editor of your choice and follow the document.", 0, 1]
end

    Intermediate Ruby Primer - repl.rb link

    # ./samples/00_learn_ruby_optional/00_intermediate_ruby_primer/app/repl.rb
# Copy and paste the code inside of the txt files here.

    Rendering Basics link

    Labels - main.rb link

    # ./samples/01_rendering_basics/01_labels/app/main.rb
=begin

APIs listing that haven't been encountered in a previous sample apps:

- args.outputs.labels: An array. Values in this array generate labels the screen.

=end

# Labels are used to represent text elements in DragonRuby

# An example of creating a label is:
# args.outputs.labels << [320, 640, "Example", 3, 1, 255, 0, 0, 200, manaspace.ttf]

# The code above does the following:
# 1. GET the place where labels go: args.outputs.labels
# 2. Request a new LABEL be ADDED: <<
# 3. The DEFINITION of a LABEL is the ARRAY:
#     [320, 640, "Example
#     [ X ,  Y,    TEXT]
# 4. It's recommended to use hashes so that you're not reliant on positional values:
#    { x: 320,
#      y: 640,
#      text: "Text",
#      font: "fonts/font.ttf",
#      anchor_x: 0.5, # or alignment_enum: 0, 1, or 2
#      anchor_y: 0.5, # or vertical_alignment_enum: 0, 1, or 2
#      r: 0,
#      g: 0,
#      b: 0,
#      a: 255,
#      size_px: 20,   # or size_enum: -10 to 10 (0 means "ledgible on small devices" ie: 20px)
#      blendmode_enum: 1 }


# The tick method is called by DragonRuby every frame
# args contains all the information regarding the game.
def tick args
  # render the current frame to the screen using a simple array
  # this is useful for quick and dirty output and is recommended to use
  # a Hash to render long term.
  args.outputs.labels << [580.5, 650, "frame: #{args.state.tick_count}"]

  # render the current frame to the screen centered vertically and horizontally at 640, 620
  args.outputs.labels << { x: 640, y: 620, anchor_x: 0.5, anchor_y: 0.5, text: "frame: #{args.state.tick_count}" }

  # Here are some examples of simple labels, with the minimum number of parameters
  # Note that the default values for the other parameters are 0, except for Alpha which is 255 and Font Style which is the default font
  args.outputs.labels << { x: 5,          y: 720 - 5, text: "This is a label located at the top left." }
  args.outputs.labels << { x: 5,          y:      30, text: "This is a label located at the bottom left." }
  args.outputs.labels << { x: 1280 - 420, y: 720 - 5, text: "This is a label located at the top right." }
  args.outputs.labels << { x: 1280 - 440, y: 30,      text: "This is a label located at the bottom right." }

  # Demonstration of the Size Enum Parameter

  # size_enum of -2 is equivalent to using size_px: 18
  args.outputs.labels << { x: 175 + 150, y: 610 - 50, text: "Smaller label.",  size_enum: -2 }

  # size_enum of -1 is equivalent to using size_px: 20
  args.outputs.labels << { x: 175 + 150, y: 580 - 50, text: "Small label.",    size_enum: -1 }

  # size_enum of  0 is equivalent to using size_px: 22
  args.outputs.labels << { x: 175 + 150, y: 550 - 50, text: "Medium label.",   size_enum:  0 }

  # size_enum of  0 is equivalent to using size_px: 24
  args.outputs.labels << { x: 175 + 150, y: 520 - 50, text: "Large label.",    size_enum:  1 }

  # size_enum of  0 is equivalent to using size_px: 26
  args.outputs.labels << { x: 175 + 150, y: 490 - 50, text: "Larger label.",   size_enum:  2 }

  # Demonstration of the Align Parameter
  args.outputs.lines  << { x: 175 + 150, y: 0, h: 720 }

  # alignment_enum: 0 is equivalent to anchor_x: 0
  args.outputs.labels << { x: 175 + 150, y: 345 - 50, text: "Left aligned.",   alignment_enum: 0 }

  # alignment_enum: 1 is equivalent to anchor_x: 0.5
  args.outputs.labels << { x: 175 + 150, y: 325 - 50, text: "Center aligned.", alignment_enum: 1 }

  # alignment_enum: 2 is equivalent to anchor_x: 1
  args.outputs.labels << { x: 175 + 150, y: 305 - 50, text: "Right aligned.",  alignment_enum: 2 }

  # Demonstration of the RGBA parameters
  args.outputs.labels << { x: 600  + 150, y: 590 - 50, text: "Red Label.",   r: 255, g:   0, b:   0 }
  args.outputs.labels << { x: 600  + 150, y: 570 - 50, text: "Green Label.", r:   0, g: 255, b:   0 }
  args.outputs.labels << { x: 600  + 150, y: 550 - 50, text: "Blue Label.",  r:   0, g:   0, b: 255 }
  args.outputs.labels << { x: 600  + 150, y: 530 - 50, text: "Faded Label.", r:   0, g:   0, b:   0, a: 128 }

  # providing a custom font
  args.outputs.labels << { x: 690 + 150,
                           y: 330 - 50,
                           text: "Custom font (Hash)",
                           size_enum: 0,                 # equivalent to size_px:  22
                           alignment_enum: 1,            # equivalent to anchor_x: 0.5
                           vertical_alignment_enum: 2,   # equivalent to anchor_y: 1
                           r: 125,
                           g: 0,
                           b: 200,
                           a: 255,
                           font: "manaspc.ttf" }

  # Primitives can hold anything, and can be given a label in the following forms
  args.outputs.primitives << { x: 690 + 150,
                               y: 330 - 80,
                               text: "Custom font (.primitives Hash)",
                               size_enum: 0,
                               alignment_enum: 1,
                               r: 125,
                               g: 0,
                               b: 200,
                               a: 255,
                               font: "manaspc.ttf" }
end

    Labels Text Wrapping - main.rb link

    # ./samples/01_rendering_basics/01_labels_text_wrapping/app/main.rb
def tick args
  # create a really long string
  args.state.really_long_string =  "Lorem ipsum dolor sit amet, consectetur adipiscing elit. In vulputate viverra metus et vehicula. Aenean quis accumsan dolor. Nulla tempus, ex et lacinia elementum, nisi felis ullamcorper sapien, sed sagittis sem justo eu lectus. Etiam ut vehicula lorem, nec placerat ligula. Duis varius ultrices magna non sagittis. Aliquam et sem vel risus viverra hendrerit. Maecenas dapibus congue lorem, a blandit mauris feugiat sit amet."
  args.state.really_long_string += "\n"
  args.state.really_long_string += "Sed quis metus lacinia mi dapibus fermentum nec id nunc. Donec tincidunt ante a sem bibendum, eget ultricies ex mollis. Quisque venenatis erat quis pretium bibendum. Pellentesque vel laoreet nibh. Cras gravida nisi nec elit pulvinar, in feugiat leo blandit. Quisque sodales quam sed congue consequat. Vivamus placerat risus vitae ex feugiat viverra. In lectus arcu, pellentesque vel ipsum ac, dictum finibus enim. Quisque consequat leo in urna dignissim, eu tristique ipsum accumsan. In eros sem, iaculis ac rhoncus eu, laoreet vitae ipsum. In sodales, ante eu tempus vehicula, mi nulla luctus turpis, eu egestas leo sapien et mi."

  # length of characters on line
  max_character_length = 80

  # line height
  line_height = 25

  long_string = args.state.really_long_string

  # API: args.string.wrapped_lines string, max_character_length
  long_strings_split = args.string.wrapped_lines long_string, max_character_length

  # render a label for each line and offset by the line_height
  args.outputs.labels << long_strings_split.map_with_index do |s, i|
    {
      x: 60,
      y: 60.from_top - (i * line_height),
      text: s
    }
  end
end

    Lines - main.rb link

    # ./samples/01_rendering_basics/02_lines/app/main.rb
=begin
APIs listing that haven't been encountered in a previous sample apps:

- args.outputs.lines: Provided an Array or a Hash, lines will be rendered to the screen.
- args.state.tick_count: This property contains an integer value that
  represents the current frame. DragonRuby renders at 60 FPS. A value of 0
  for args.state.tick_count represents the initial load of the game.
=end

# The parameters required for lines are:
# 1. The initial point (x, y)
# 2. The end point (x2, y2)
# 3. The rgba values for the color and transparency (r, g, b, a)
#    Creating a line using an Array (quick and dirty):
#    [x, y, x2, y2, r, g, b, a]
#    args.outputs.lines << [100, 100, 300, 300, 255, 0, 255, 255]
#    This would create a line from (100, 100) to (300, 300)
#    The RGB code (255, 0, 255) would determine its color, a purple
#    It would have an Alpha value of 255, making it completely opaque
# 4. Using Hashes, the keys are :x, :y, :x2, :y2, :r, :g, :b, and :a
def tick args
  args.outputs.labels << { x: 640,
                           y: 700,
                           text: "Sample app shows how to create lines.",
                           size_px: 22,
                           anchor_x: 0.5,
                           anchor_y: 0.5 }

  # Render lines using Arrays/Tuples
  # This is quick and dirty and it's recommended to use Hashes long term
  args.outputs.lines  << [380, 450, 675, 450]
  args.outputs.lines  << [380, 410, 875, 410]

  # These examples utilize args.state.tick_count to change the length of the lines over time
  # args.state.tick_count is the ticks that have occurred in the game
  # This is accomplished by making either the starting or ending point based on the args.state.tick_count
  args.outputs.lines  << { x:  380,
                           y:  370,
                           x2: 875,
                           y2: 370,
                           r:  args.state.tick_count % 255,
                           g:  0,
                           b:  0,
                           a:  255 }

  args.outputs.lines  << { x:  380,
                           y:  330 - args.state.tick_count % 25,
                           x2: 875,
                           y2: 330,
                           r:  0,
                           g:  0,
                           b:  0,
                           a:  255 }

  args.outputs.lines  << { x:  380 + args.state.tick_count % 400,
                           y:  290,
                           x2: 875,
                           y2: 290,
                           r:  0,
                           g:  0,
                           b:  0,
                           a:  255 }
end

    Solids Borders - main.rb link

    # ./samples/01_rendering_basics/03_solids_borders/app/main.rb
=begin
APIs listing that haven't been encountered in a previous sample apps:

- args.outputs.solids: Provided an Array or a Hash, solid squares will be
  rendered to the screen.
- args.outputs.borders: Provided an Array or a Hash, borders
  will be rendered to the screen.
- args.outputs.primitives: Provided an Hash with a :primitive_marker key,
  either a solid square or border will be rendered to the screen.
=end

# The parameters required for rects are:
# 1. The bottom left corner (x, y)
# 2. The width (w)
# 3. The height (h)
# 4. The rgba values for the color and transparency (r, g, b, a)
# [100, 100, 400, 500, 0, 255, 0, 180]
# Whether the rect would be filled or not depends on if
# it is added to args.outputs.solids or args.outputs.borders
# (or its :primitive_marker if Hash is sent to args.outputs.primitives)
def tick args
  args.outputs.labels << { x: 640,
                           y: 700,
                           text: "Sample app shows how to create solid squares and borders.",
                           size_px: 22,
                           anchor_x: 0.5,
                           anchor_y: 0.5 }

  # Render solids/borders using Arrays/Tuples
  # This is quick and dirty and it's recommended to use Hashes long term
  args.outputs.solids << [470, 520, 50, 50]
  args.outputs.solids << [530, 520, 50, 50, 0, 0, 0]
  args.outputs.solids << [590, 520, 50, 50, 255, 0, 0]
  args.outputs.solids << [650, 520, 50, 50, 255, 0, 0, 128]

  args.outputs.borders << [470, 320, 50, 50]
  args.outputs.borders << [530, 320, 50, 50, 0, 0, 0]
  args.outputs.borders << [590, 320, 50, 50, 255, 0, 0]
  args.outputs.borders << [650, 320, 50, 50, 255, 0, 0, 128]

  # using Hashes
  args.outputs.solids << { x: 710,
                           y: 520,
                           w: 50,
                           h: 50,
                           r: 0,
                           g: 80,
                           b: 40,
                           a: args.state.tick_count % 255 }

  # primitives outputs requires a primitive_marker to differentiate
  # between a solid or a border
  args.outputs.primitives << { x: 770,
                               y: 520,
                               w: 50,
                               h: 50,
                               r: 0,
                               g: 80,
                               b: 40,
                               a: args.state.tick_count % 255,
                               primitive_marker: :solid }

  args.outputs.borders << { x: 710,
                            y: 320,
                            w: 50,
                            h: 50,
                            r: 0,
                            g: 80,
                            b: 40,
                            a: args.state.tick_count % 255 }

  # primitives outputs requires a primitive_marker to differentiate
  # between a solid or a border
  args.outputs.borders << { x: 770,
                            y: 320,
                            w: 50,
                            h: 50,
                            r: 0,
                            g: 80,
                            b: 40,
                            a: args.state.tick_count % 255,
                            primitive_marker: :border }
end

    Sprites - main.rb link

    # ./samples/01_rendering_basics/04_sprites/app/main.rb
=begin
APIs listing that haven't been encountered in a previous sample apps:
- args.outputs.sprites: Provided an Array or a Hash, a sprite will be
  rendered to the screen.

Properties of a sprite:
{
  # common properties
  x: 0,
  y: 0,
  w: 100,
  h: 100,
  path: "sprites/square/blue.png",
  angle: 90,
  a: 255,

  # anchoring (float value representing a percentage to offset w and h)
  anchor_x: 0,
  anchor_y: 0,
  angle_anchor_x: 0,
  angle_anchor_y: 0,

  # color saturation
  r: 255,
  g: 255,
  b: 255,

  # flip rendering
  flip_horizontally: false,
  flip_vertically: false

  # sprite sheet properties/clipped rect (using the top-left as the origin)
  tile_x: 0,
  tile_y: 0,
  tile_w: 20,
  tile_h: 20

  # sprite sheet properties/clipped rect (using the bottom-left as the origin)
  source_x: 0,
  source_y: 0,
  source_w: 20,
  source_h: 20,
}
=end
def tick args
  args.outputs.labels << { x: 640,
                           y: 700,
                           text: "Sample app shows how to render a sprite.",
                           size_px: 22,
                           anchor_x: 0.5,
                           anchor_y: 0.5 }

  # ==================
  # ROW 1 Simple Rendering
  # ==================
  args.outputs.labels << { x: 460,
                           y: 600,
                           text: "Simple rendering." }

  # using quick and dirty Array (use Hashes for long term maintainability)
  args.outputs.sprites << [460, 470, 128, 101, 'dragonruby.png']

  # using Hashes
  args.outputs.sprites << { x: 610,
                            y: 470,
                            w: 128,
                            h: 101,
                            path: 'dragonruby.png',
                            a: args.state.tick_count % 255 }

  args.outputs.sprites << { x: 760 + 64,
                            y: 470 + 50,
                            w: 128,
                            h: 101,
                            anchor_x: 0.5,
                            anchor_y: 0.5,
                            path: 'dragonruby.png',
                            flip_horizontally: true,
                            flip_vertically: true,
                            a: args.state.tick_count % 255 }

  # ==================
  # ROW 2 Angle/Angle Anchors
  # ==================
  args.outputs.labels << { x: 460,
                           y: 400,
                           text: "Angle/Angle Anchors." }
  # rotation using angle (in degrees)
  args.outputs.sprites << { x: 460,
                            y: 270,
                            w: 128,
                            h: 101,
                            path: 'dragonruby.png',
                            angle: args.state.tick_count % 360 }

  # rotation anchor using angle_anchor_x
  args.outputs.sprites << { x: 760,
                            y: 270,
                            w: 128,
                            h: 101,
                            path: 'dragonruby.png',
                            angle: args.state.tick_count % 360,
                            angle_anchor_x: 0,
                            angle_anchor_y: 0 }

  # ==================
  # ROW 3 Sprite Cropping
  # ==================
  args.outputs.labels << { x: 460,
                           y: 200,
                           text: "Cropping (tile sheets)." }

  # tiling using top left as the origin
  args.outputs.sprites << { x: 460,
                            y: 90,
                            w: 80,
                            h: 80,
                            path: 'dragonruby.png',
                            tile_x: 0,
                            tile_y: 0,
                            tile_w: 80,
                            tile_h: 80 }

  # overlay to see how tile_* crops
  args.outputs.sprites << { x: 460,
                            y: 70,
                            w: 128,
                            h: 101,
                            path: 'dragonruby.png',
                            a: 80 }

  # tiling using bottom left as the origin
  args.outputs.sprites << { x: 610,
                            y: 70,
                            w: 80,
                            h: 80,
                            path: 'dragonruby.png',
                            source_x: 0,
                            source_y: 0,
                            source_w: 80,
                            source_h: 80 }

  # overlay to see how source_* crops
  args.outputs.sprites << { x: 610,
                            y: 70,
                            w: 128,
                            h: 101,
                            path: 'dragonruby.png',
                            a: 80 }
end

    Sounds - main.rb link

    # ./samples/01_rendering_basics/05_sounds/app/main.rb
=begin

 APIs Listing that haven't been encountered in previous sample apps:

 - sample: Chooses random element from array.
   In this sample app, the target note is set by taking a sample from the collection
   of available notes.

 Reminders:

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.
=end

# This sample app allows users to test their musical skills by matching the piano sound that plays in each
# level to the correct note.

# Runs all the methods necessary for the game to function properly.
def tick args
  args.outputs.labels << [640, 360, "Click anywhere to play a random sound.", 0, 1]
  args.state.notes ||= [:C3, :D3, :E3, :F3, :G3, :A3, :B3, :C4]

  if args.inputs.mouse.click
    # Play a sound by adding a string to args.outputs.sounds
    args.outputs.sounds << "sounds/#{args.state.notes.sample}.wav" # sound of target note is output
  end
end

    Input Basics link

    Keyboard - main.rb link

    # ./samples/02_input_basics/01_keyboard/app/main.rb
=begin

APIs listing that haven't been encountered in a previous sample apps:

- args.inputs.keyboard.key_up.KEY: The value of the properties will be set
  to the frame  that the key_up event occurred (the frame correlates
  to args.state.tick_count). Otherwise the value will be nil. For a
  full listing of keys, take a look at mygame/documentation/06-keyboard.md.
- args.state.PROPERTY: The state property on args is a dynamic
  structure. You can define ANY property here with ANY type of
  arbitrary nesting. Properties defined on args.state will be retained
  across frames. If you attempt access a property that doesn't exist
  on args.state, it will simply return nil (no exception will be thrown).

=end

# Along with outputs, inputs are also an essential part of video game development
# DragonRuby can take input from keyboards, mouse, and controllers.
# This sample app will cover keyboard input.

# args.inputs.keyboard.key_up.a will check to see if the a key has been pressed
# This will work with the other keys as well


def tick args
  tick_instructions args, "Sample app shows how keyboard events are registered and accessed.", 360
  args.outputs.labels << { x: 460, y: row_to_px(args, 0), text: "Current game time: #{args.state.tick_count}", size_enum: -1 }
  args.outputs.labels << { x: 460, y: row_to_px(args, 2), text: "Keyboard input: args.inputs.keyboard.key_up.h", size_enum: -1 }
  args.outputs.labels << { x: 460, y: row_to_px(args, 3), text: "Press \"h\" on the keyboard.", size_enum: -1 }

  # Input on a specifc key can be found through args.inputs.keyboard.key_up followed by the key
  if args.inputs.keyboard.key_up.h
    args.state.h_pressed_at = args.state.tick_count
  end

  # This code simplifies to if args.state.h_pressed_at has not been initialized, set it to false
  args.state.h_pressed_at ||= false

  if args.state.h_pressed_at
    args.outputs.labels << { x: 460, y: row_to_px(args, 4), text: "\"h\" was pressed at time: #{args.state.h_pressed_at}", size_enum: -1 }
  else
    args.outputs.labels << { x: 460, y: row_to_px(args, 4), text: "\"h\" has never been pressed.", size_enum: -1 }
  end

  tick_help_text args
end

def row_to_px args, row_number, y_offset = 20
  # This takes a row_number and converts it to pixels DragonRuby understands.
  # Row 0 starts 5 units below the top of the grid
  # Each row afterward is 20 units lower
  args.grid.top - 5 - (y_offset * row_number)
end

# Don't worry about understanding the code within this method just yet.
# This method shows you the help text within the game.
def tick_help_text args
  return unless args.state.h_pressed_at

  args.state.key_value_history      ||= {}
  args.state.key_down_value_history ||= {}
  args.state.key_held_value_history ||= {}
  args.state.key_up_value_history   ||= {}

  if (args.inputs.keyboard.key_down.truthy_keys.length > 0 ||
      args.inputs.keyboard.key_held.truthy_keys.length > 0 ||
      args.inputs.keyboard.key_up.truthy_keys.length > 0)
    args.state.help_available = true
    args.state.no_activity_debounce = nil
  else
    args.state.no_activity_debounce ||= 5.seconds
    args.state.no_activity_debounce -= 1
    if args.state.no_activity_debounce <= 0
      args.state.help_available = false
      args.state.key_value_history        = {}
      args.state.key_down_value_history   = {}
      args.state.key_held_value_history   = {}
      args.state.key_up_value_history     = {}
    end
  end

  args.outputs.labels << { x: 10, y: row_to_px(args, 6), text: "This is the api for the keys you've pressed:", size_enum: -1, r: 180 }

  if !args.state.help_available
    args.outputs.labels << [10, row_to_px(args, 7),  "Press a key and I'll show code to access the key and what value will be returned if you used the code."]
    return
  end

  args.outputs.labels << { x: 10 , y: row_to_px(args, 7), text: "args.inputs.keyboard",          size_enum: -2 }
  args.outputs.labels << { x: 330, y: row_to_px(args, 7), text: "args.inputs.keyboard.key_down", size_enum: -2 }
  args.outputs.labels << { x: 650, y: row_to_px(args, 7), text: "args.inputs.keyboard.key_held", size_enum: -2 }
  args.outputs.labels << { x: 990, y: row_to_px(args, 7), text: "args.inputs.keyboard.key_up",   size_enum: -2 }

  fill_history args, :key_value_history,      :down_or_held, nil
  fill_history args, :key_down_value_history, :down,        :key_down
  fill_history args, :key_held_value_history, :held,        :key_held
  fill_history args, :key_up_value_history,   :up,          :key_up

  render_help_labels args, :key_value_history,      :down_or_held, nil,      10
  render_help_labels args, :key_down_value_history, :down,        :key_down, 330
  render_help_labels args, :key_held_value_history, :held,        :key_held, 650
  render_help_labels args, :key_up_value_history,   :up,          :key_up,   990
end

def fill_history args, history_key, state_key, keyboard_method
  fill_single_history args, history_key, state_key, keyboard_method, :raw_key
  fill_single_history args, history_key, state_key, keyboard_method, :char
  args.inputs.keyboard.keys[state_key].each do |key_name|
    fill_single_history args, history_key, state_key, keyboard_method, key_name
  end
end

def fill_single_history args, history_key, state_key, keyboard_method, key_name
  current_value = args.inputs.keyboard.send(key_name)
  if keyboard_method
    current_value = args.inputs.keyboard.send(keyboard_method).send(key_name)
  end
  args.state.as_hash[history_key][key_name] ||= []
  args.state.as_hash[history_key][key_name] << current_value
  args.state.as_hash[history_key][key_name] = args.state.as_hash[history_key][key_name].reverse.uniq.take(3).reverse
end

def render_help_labels args, history_key, state_key, keyboard_method, x
  idx = 8
  args.outputs.labels << args.state
                           .as_hash[history_key]
                           .keys
                           .reverse
                           .map
                           .with_index do |k, i|
    v = args.state.as_hash[history_key][k]
    current_value = args.inputs.keyboard.send(k)
    if keyboard_method
      current_value = args.inputs.keyboard.send(keyboard_method).send(k)
    end
    idx += 2
    [
      { x: x, y: row_to_px(args, idx + 0, 16), text: "    .#{k} is #{current_value || "nil"}", size_enum: -2 },
      { x: x, y: row_to_px(args, idx + 1, 16), text: "       was #{v}", size_enum: -2 }
    ]
  end
end


def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << { x: 0,   y: y - 50, w: 1280, h: 60 }.solid!
  args.outputs.debug << { x: 640, y: y,      text: text,
                          size_enum: 1, alignment_enum: 1, r: 255, g: 255, b: 255 }.label!
  args.outputs.debug << { x: 640, y: y - 25, text: "(click to dismiss instructions)",
                          size_enum: -2, alignment_enum: 1, r: 255, g: 255, b: 255 }.label!
end

    Moving A Sprite - main.rb link

    # ./samples/02_input_basics/01_moving_a_sprite/app/main.rb
def tick args
  # Create a player and set default values
  # NOTE: args.state is a construct that lets you define properties on the fly
  args.state.player ||= { x: 100,
                          y: 100,
                          w: 50,
                          h: 50,
                          path: 'sprites/square/green.png' }

  # move the player around by consulting args.inputs
  # the top level args.inputs checks the keyboard's arrow keys, WASD,
  # and controller one
  if args.inputs.up
    args.state.player.y += 10
  elsif args.inputs.down
    args.state.player.y -= 10
  end

  if args.inputs.left
    args.state.player.x -= 10
  elsif args.inputs.right
    args.state.player.x += 10
  end

  # Render the player to the screen
  args.outputs.sprites << args.state.player
end

    Mouse - main.rb link

    # ./samples/02_input_basics/02_mouse/app/main.rb
=begin

APIs that haven't been encountered in a previous sample apps:

- args.inputs.mouse.click: This property will be set if the mouse was clicked.
- args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.
- args.inputs.mouse.click.point.created_at: The frame the mouse click occurred in.
- args.inputs.mouse.click.point.created_at_elapsed: How many frames have passed
  since the click event.

Reminder:

- args.state.PROPERTY: The state property on args is a dynamic
  structure. You can define ANY property here with ANY type of
  arbitrary nesting. Properties defined on args.state will be retained
  across frames. If you attempt access a property that doesn't exist
  on args.state, it will simply return nil (no exception will be thrown).

=end

# This code demonstrates DragonRuby mouse input

# To see if the a mouse click occurred
# Use args.inputs.mouse.click
# Which returns a boolean

# To see where a mouse click occurred
# Use args.inputs.mouse.click.point.x AND
# args.inputs.mouse.click.point.y

# To see which frame the click occurred
# Use args.inputs.mouse.click.created_at

# To see how many frames its been since the click occurred
# Use args.inputs.mouse.click.created_at_elapsed

# Saving the click in args.state can be quite useful

def tick args
  args.outputs.labels << { x: 640,
                           y: 700,
                           anchor_x: 0.5,
                           anchor_y: 0.5,
                           text: "Sample app shows how mouse events are registered and how to measure elapsed time." }
  x = 460

  args.outputs.labels << small_label(args, x, 11, "Mouse input: args.inputs.mouse")

  if args.inputs.mouse.click
    args.state.last_mouse_click = args.inputs.mouse.click
  end

  if args.state.last_mouse_click
    click = args.state.last_mouse_click
    args.outputs.labels << small_label(args, x, 12, "Mouse click happened at: #{click.created_at}")
    args.outputs.labels << small_label(args, x, 13, "Mouse clicked #{click.created_at_elapsed} ticks ago")
    args.outputs.labels << small_label(args, x, 14, "Mouse click location: #{click.point.x}, #{click.point.y}")
  else
    args.outputs.labels << small_label(args, x, 12, "Mouse click has not occurred yet.")
    args.outputs.labels << small_label(args, x, 13, "Please click mouse.")
  end
end

def small_label args, x, row, message
  { x: x,
    y: 720 - 5 - 20 * row,
    text: message }
end

    Mouse Point To Rect - main.rb link

    # ./samples/02_input_basics/03_mouse_point_to_rect/app/main.rb
=begin
- Example usage of Hash#inside_rect? to determine if a mouse click happened
  inside of a box.
  ```
  rect_1 = { x: 100, y: 100, w:   1, h:   1 }
  rect_2 = { x:   0, y:   0, w: 500, h: 500 }
  result = rect_1.inside_rect? rect_2
  ```
=end
def tick args
  # initialize the rectangle
  args.state.box ||= { x: 785, y: 370, w: 50, h: 50, r: 0, g: 0, b: 170 }

  # store the mouse click and the frame the click occured
  # and whether it was inside or outside the box
  if args.inputs.mouse.click
    args.state.last_mouse_click = args.inputs.mouse.click
    args.state.last_mouse_click_at = args.state.tick_count
    if args.state.last_mouse_click.inside_rect? args.state.box
      args.state.was_inside_rect = true
    else
      args.state.was_inside_rect = false
    end
  end

  # render
  args.outputs.labels << { x: 640, y: 700, anchor_x: 0.5, anchor_y: 0.5, text: "Sample app shows how to determine if a click happened inside a rectangle." }
  args.outputs.labels << { x: 340, y: 420, text:  "Click inside (or outside) the blue box ---->" }

  args.outputs.borders << args.state.box

  if args.state.last_mouse_click
    if args.state.was_inside_rect
      args.outputs.labels << { x: 810,
                               y: 340,
                               anchor_x: 0.5,
                               anchor_y: 0.5,
                               text: "Mouse click happened *inside* the box [frame #{args.state.last_mouse_click_at}]." }
    else
      args.outputs.labels << { x: 810,
                               y: 340,
                               anchor_x: 0.5,
                               anchor_y: 0.5,
                               text: "Mouse click happened *outside* the box [frame #{args.state.last_mouse_click_at}]." }
    end
  else
    args.outputs.labels << { x: 810,
                             y: 340,
                             anchor_x: 0.5,
                             anchor_y: 0.5,
                             text: "Waiting for mouse click..." }
  end
end

    Mouse Drag And Drop - main.rb link

    # ./samples/02_input_basics/04_mouse_drag_and_drop/app/main.rb
def tick args
  # create 10 random squares on the screen
  if !args.state.squares
    # the squares will be contained in lookup/Hash so that we can access via their id
    args.state.squares = {}
    10.times_with_index do |id|
      # for each square, store it in the hash with
      # the id (we're just using the index 0-9 as the index)
      args.state.squares[id] = {
        id: id,
        x: 100 + (rand * 1080),
        y: 100 + (520 * rand),
        w: 100,
        h: 100,
        path: "sprites/square/blue.png"
      }
    end
  end

  # two key variables are set here
  # - square_reference: this represents the square that is currently being dragged
  # - square_under_mouse: this represents the square that the mouse is currently being hovered over
  if args.state.currently_dragging_square_id
    # if the currently_dragging_square_id is set, then set the "square_under_mouse" to
    # the same square as square_reference
    square_reference = args.state.squares[args.state.currently_dragging_square_id]
    square_under_mouse = square_reference
  else
    # if currently_dragging_square_id isn't set, then see if there is a square that
    # the mouse is currently hovering over (the square reference will be nil since
    # we haven't selected a drag target yet)
    square_under_mouse = args.geometry.find_intersect_rect args.inputs.mouse, args.state.squares.values
    square_reference = nil
  end


  # if a click occurs, and there is a square under the mouse
  if args.inputs.mouse.click && square_under_mouse
    # capture the id of the square that the mouse is hovering over
    args.state.currently_dragging_square_id = square_under_mouse.id

    # also capture where in the square the mouse was clicked so that
    # the movement of the square will smoothly transition with the mouse's
    # location
    args.state.mouse_point_inside_square = {
      x: args.inputs.mouse.x - square_under_mouse.x,
      y: args.inputs.mouse.y - square_under_mouse.y,
    }
  elsif args.inputs.mouse.held && args.state.currently_dragging_square_id
    # if the mouse is currently being held and the currently_dragging_square_id was set,
    # then update the x and y location of the referenced square (taking into consideration the
    # relative position of the mouse when the square was clicked)
    square_reference.x = args.inputs.mouse.x - args.state.mouse_point_inside_square.x
    square_reference.y = args.inputs.mouse.y - args.state.mouse_point_inside_square.y
  elsif args.inputs.mouse.up
    # if the mouse is released, then clear out the currently_dragging_square_id
    args.state.currently_dragging_square_id = nil
  end

  # render all the squares on the screen
  args.outputs.sprites << args.state.squares.values

  # if there was a square under the mouse, add an "overlay"
  if square_under_mouse
    args.outputs.sprites << square_under_mouse.merge(path: "sprites/square/red.png")
  end
end

    Mouse Rect To Rect - main.rb link

    # ./samples/02_input_basics/04_mouse_rect_to_rect/app/main.rb
=begin

APIs that haven't been encountered in a previous sample apps:

- args.outputs.borders: An array. Values in this array will be rendered as
  unfilled rectangles on the screen.
- ARRAY#intersect_rect?: An array with at least four values is
  considered a rect. The intersect_rect? function returns true
  or false depending on if the two rectangles intersect.

  ```
  # Rect One: x: 100, y: 100, w: 100, h: 100
  # Rect Two: x: 0, y: 0, w: 500, h: 500
  # Result:   true

  [100, 100, 100, 100].intersect_rect? [0, 0, 500, 500]
  ```

  ```
  # Rect One: x: 100, y: 100, w: 10, h: 10
  # Rect Two: x: 500, y: 500, w: 10, h: 10
  # Result:   false

  [100, 100, 10, 10].intersect_rect? [500, 500, 10, 10]
  ```

=end

# Similarly, whether rects intersect can be found through
# rect1.intersect_rect? rect2

def tick args
  tick_instructions args, "Sample app shows how to determine if two rectangles intersect."
  x = 460

  args.outputs.labels << small_label(args, x, 3, "Click anywhere on the screen")
  # red_box = [460, 250, 355, 90, 170, 0, 0]
  # args.outputs.borders << red_box

  # args.state.box_collision_one and args.state.box_collision_two
  # Are given values of a solid when they should be rendered
  # They are stored in game so that they do not get reset every tick
  if args.inputs.mouse.click
    if !args.state.box_collision_one
      args.state.box_collision_one = { x: args.inputs.mouse.click.point.x - 25,
                                       y: args.inputs.mouse.click.point.y - 25,
                                       w: 125, h: 125,
                                       r: 180, g: 0, b: 0, a: 180 }
    elsif !args.state.box_collision_two
      args.state.box_collision_two = { x: args.inputs.mouse.click.point.x - 25,
                                       y: args.inputs.mouse.click.point.y - 25,
                                       w: 125, h: 125,
                                       r: 0, g: 0, b: 180, a: 180 }
    else
      args.state.box_collision_one = nil
      args.state.box_collision_two = nil
    end
  end

  if args.state.box_collision_one
    args.outputs.solids << args.state.box_collision_one
  end

  if args.state.box_collision_two
    args.outputs.solids << args.state.box_collision_two
  end

  if args.state.box_collision_one && args.state.box_collision_two
    if args.state.box_collision_one.intersect_rect? args.state.box_collision_two
      args.outputs.labels << small_label(args, x, 4, 'The boxes intersect.')
    else
      args.outputs.labels << small_label(args, x, 4, 'The boxes do not intersect.')
    end
  else
    args.outputs.labels << small_label(args, x, 4, '--')
  end
end

def small_label args, x, row, message
  { x: x, y: row_to_px(args, row), text: message, size_enum: -2 }
end

def row_to_px args, row_number
  args.grid.top - 5 - (20 * row_number)
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Controller - main.rb link

    # ./samples/02_input_basics/05_controller/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - args.current_controller.key_held.KEY: Will check to see if a specific key
   is being held down on the controller.
   If there is more than one controller being used, they can be differentiated by
   using names like controller_one and controller_two.

   For a full listing of buttons, take a look at mygame/documentation/08-controllers.md.

 Reminder:

 - args.state.PROPERTY: The state property on args is a dynamic
   structure. You can define ANY property here with ANY type of
   arbitrary nesting. Properties defined on args.state will be retained
   across frames. If you attempt to access a property that doesn't exist
   on args.state, it will simply return nil (no exception will be thrown).

   In this sample app, args.state.BUTTONS is an array that stores the buttons of the controller.
   The parameters of a button are:
   1. the position (x, y)
   2. the input key held on the controller
   3. the text or name of the button

=end

# This sample app provides a visual demonstration of a standard controller, including
# the placement and function of all buttons.

class ControllerDemo
  attr_accessor :inputs, :state, :outputs

  # Calls the methods necessary for the app to run successfully.
  def tick
    process_inputs
    render
  end

  # Starts with an empty collection of buttons.
  # Adds buttons that are on the controller to the collection.
  def process_inputs
    state.target  ||= :controller_one
    state.buttons = []

    if inputs.keyboard.key_down.tab
      if state.target == :controller_one
        state.target = :controller_two
      elsif state.target == :controller_two
        state.target = :controller_three
      elsif state.target == :controller_three
        state.target = :controller_four
      elsif state.target == :controller_four
        state.target = :controller_one
      end
    end

    state.buttons << { x: 100,  y: 500, active: current_controller.key_held.l1, text: "L1"}
    state.buttons << { x: 100,  y: 600, active: current_controller.key_held.l2, text: "L2"}
    state.buttons << { x: 1100, y: 500, active: current_controller.key_held.r1, text: "R1"}
    state.buttons << { x: 1100, y: 600, active: current_controller.key_held.r2, text: "R2"}
    state.buttons << { x: 540,  y: 450, active: current_controller.key_held.select, text: "Select"}
    state.buttons << { x: 660,  y: 450, active: current_controller.key_held.start, text: "Start"}
    state.buttons << { x: 200,  y: 300, active: current_controller.key_held.left, text: "Left"}
    state.buttons << { x: 300,  y: 400, active: current_controller.key_held.up, text: "Up"}
    state.buttons << { x: 400,  y: 300, active: current_controller.key_held.right, text: "Right"}
    state.buttons << { x: 300,  y: 200, active: current_controller.key_held.down, text: "Down"}
    state.buttons << { x: 800,  y: 300, active: current_controller.key_held.x, text: "X"}
    state.buttons << { x: 900,  y: 400, active: current_controller.key_held.y, text: "Y"}
    state.buttons << { x: 1000, y: 300, active: current_controller.key_held.a, text: "A"}
    state.buttons << { x: 900,  y: 200, active: current_controller.key_held.b, text: "B"}
    state.buttons << { x: 450 + current_controller.left_analog_x_perc * 100,
                       y: 100 + current_controller.left_analog_y_perc * 100,
                       active: current_controller.key_held.l3,
                       text: "L3" }
    state.buttons << { x: 750 + current_controller.right_analog_x_perc * 100,
                       y: 100 + current_controller.right_analog_y_perc * 100,
                       active: current_controller.key_held.r3,
                       text: "R3" }
  end

  # Gives each button a square shape.
  # If the button is being pressed or held (which means it is considered active),
  # the square is filled in. Otherwise, the button simply has a border.
  def render
    state.buttons.each do |b|
      rect = { x: b.x, y: b.y, w: 75, h: 75 }

      if b.active # if button is pressed
        outputs.solids << rect # rect is output as solid (filled in)
      else
        outputs.borders << rect # otherwise, output as border
      end

      # Outputs the text of each button using labels.
      outputs.labels << { x: b.x, y: b.y + 95, text: b.text } # add 95 to place label above button
    end

    outputs.labels << { x:  10, y: 60, text: "Left Analog x: #{current_controller.left_analog_x_raw} (#{current_controller.left_analog_x_perc * 100}%)" }
    outputs.labels << { x:  10, y: 30, text: "Left Analog y: #{current_controller.left_analog_y_raw} (#{current_controller.left_analog_y_perc * 100}%)" }
    outputs.labels << { x: 1270, y: 60, text: "Right Analog x: #{current_controller.right_analog_x_raw} (#{current_controller.right_analog_x_perc * 100}%)", alignment_enum: 2 }
    outputs.labels << { x: 1270, y: 30, text: "Right Analog y: #{current_controller.right_analog_y_raw} (#{current_controller.right_analog_y_perc * 100}%)" , alignment_enum: 2 }

    outputs.labels << { x: 640, y: 60, text: "Target: #{state.target} (press tab to go to next controller)", alignment_enum: 1 }
    outputs.labels << { x: 640, y: 30, text: "Connected: #{current_controller.connected}", alignment_enum: 1 }
  end

  def current_controller
    if state.target == :controller_one
      return inputs.controller_one
    elsif state.target == :controller_two
      return inputs.controller_two
    elsif state.target == :controller_three
      return inputs.controller_three
    elsif state.target == :controller_four
      return inputs.controller_four
    end
  end
end

$controller_demo = ControllerDemo.new

def tick args
  tick_instructions args, "Sample app shows how controller input is handled. You'll need to connect a USB controller."
  $controller_demo.inputs = args.inputs
  $controller_demo.state = args.state
  $controller_demo.outputs = args.outputs
  $controller_demo.tick
end

# Resets the app.
def r
  $gtk.reset
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Touch - main.rb link

    # ./samples/02_input_basics/06_touch/app/main.rb
def tick args
  args.outputs.background_color = [ 0, 0, 0 ]
  args.outputs.primitives << [640, 700, "Touch your screen.", 5, 1, 255, 255, 255].label

  # If you don't want to get fancy, you can just look for finger_one
  #  (and _two, if you like), which are assigned in the order new touches hit
  #  the screen. If not nil, they are touching right now, and are just
  #  references to specific items in the args.input.touch hash.
  # If finger_one lifts off, it will become nil, but finger_two, if it was
  #  touching, remains until it also lifts off. When all fingers lift off, the
  #  the next new touch will be finger_one again, but until then, new touches
  #  don't fill in earlier slots.
  if !args.inputs.finger_one.nil?
    args.outputs.primitives << { x: 640, y: 650, text: "Finger #1 is touching at (#{args.inputs.finger_one.x}, #{args.inputs.finger_one.y}).",
                                 size_enum: 5, alignment_enum: 1, r: 255, g: 255, b: 255 }.label!
  end
  if !args.inputs.finger_two.nil?
    args.outputs.primitives << { x: 640, y: 600, text: "Finger #2 is touching at (#{args.inputs.finger_two.x}, #{args.inputs.finger_two.y}).",
                                 size_enum: 5, alignment_enum: 1, r: 255, g: 255, b: 255 }.label!
  end

  # Here's the more flexible interface: this will report as many simultaneous
  #  touches as the system can handle, but it's a little more effort to track
  #  them. Each item in the args.input.touch hash has a unique key (an
  #  incrementing integer) that exists until the finger lifts off. You can
  #  tell which order the touches happened globally by the key value, or
  #  by the touch[id].touch_order field, which resets to zero each time all
  #  touches have lifted.

  args.state.colors ||= [
    0xFF0000, 0x00FF00, 0x1010FF, 0xFFFF00, 0xFF00FF, 0x00FFFF, 0xFFFFFF
  ]

  size = 100
  args.inputs.touch.each { |k,v|
    color = args.state.colors[v.touch_order % 7]
    r = (color & 0xFF0000) >> 16
    g = (color & 0x00FF00) >> 8
    b = (color & 0x0000FF)
    args.outputs.primitives << { x: v.x - (size / 2), y: v.y + (size / 2), w: size, h: size, r: r, g: g, b: b, a: 255 }.solid!
    args.outputs.primitives << { x: v.x, y: v.y + size, text: k.to_s, alignment_enum: 1 }.label!
  }
end

    Managing Scenes - main.rb link

    # ./samples/02_input_basics/07_managing_scenes/app/main.rb
def tick args
  # initialize the scene to scene 1
  args.state.current_scene ||= :title_scene
  # capture the current scene to verify it didn't change through
  # the duration of tick
  current_scene = args.state.current_scene

  # tick whichever scene is current
  case current_scene
  when :title_scene
    tick_title_scene args
  when :game_scene
    tick_game_scene args
  when :game_over_scene
    tick_game_over_scene args
  end

  # make sure that the current_scene flag wasn't set mid tick
  if args.state.current_scene != current_scene
    raise "Scene was changed incorrectly. Set args.state.next_scene to change scenes."
  end

  # if next scene was set/requested, then transition the current scene to the next scene
  if args.state.next_scene
    args.state.current_scene = args.state.next_scene
    args.state.next_scene = nil
  end
end

def tick_title_scene args
  args.outputs.labels << { x: 640,
                           y: 360,
                           text: "Title Scene (click to go to game)",
                           alignment_enum: 1 }

  if args.inputs.mouse.click
    args.state.next_scene = :game_scene
  end
end

def tick_game_scene args
  args.outputs.labels << { x: 640,
                           y: 360,
                           text: "Game Scene (click to go to game over)",
                           alignment_enum: 1 }

  if args.inputs.mouse.click
    args.state.next_scene = :game_over_scene
  end
end

def tick_game_over_scene args
  args.outputs.labels << { x: 640,
                           y: 360,
                           text: "Game Over Scene (click to go to title)",
                           alignment_enum: 1 }

  if args.inputs.mouse.click
    args.state.next_scene = :title_scene
  end
end

    Rendering Sprites link

    Animation Using Separate Pngs - main.rb link

    # ./samples/03_rendering_sprites/01_animation_using_separate_pngs/app/main.rb
=begin
 Reminders:

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

   In this sample app, we're using string interpolation to iterate through images in the
   sprites folder using their image path names.

 - args.outputs.sprites: An array. Values in this array generate sprites on the screen.
   The parameters are [X, Y, WIDTH, HEIGHT, IMAGE PATH]
   For more information about sprites, go to mygame/documentation/05-sprites.md.

 - args.outputs.labels: An array. Values in the array generate labels on the screen.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - args.inputs.keyboard.key_down.KEY: Determines if a key is in the down state, or pressed.
   Stores the frame that key was pressed on.
   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.

=end

# This sample app demonstrates how sprite animations work.
# There are two sprites that animate forever and one sprite
# that *only* animates when you press the "f" key on the keyboard.

# This is the entry point to your game. The `tick` method
# executes at 60 frames per second. There are two methods
# in this tick "entry point": `looping_animation`, and the
# second method is `one_time_animation`.
def tick args
  # uncomment the line below to see animation play out in slow motion
  # args.gtk.slowmo! 6
  looping_animation args
  one_time_animation args
end

# This function shows how to animate a sprite that loops forever.
def looping_animation args
  # Here we define a few local variables that will be sent
  # into the magic function that gives us the correct sprite image
  # over time. There are four things we need in order to figure
  # out which sprite to show.

  # 1. When to start the animation.
  start_looping_at = 0

  # 2. The number of pngs that represent the full animation.
  number_of_sprites = 6

  # 3. How long to show each png.
  number_of_frames_to_show_each_sprite = 4

  # 4. Whether the animation should loop once, or forever.
  does_sprite_loop = true

  # With the variables defined above, we can get a number
  # which represents the sprite to show by calling the `frame_index` function.
  # In this case the number will be between 0, and 5 (you can see the sprites
  # in the ./sprites directory).
  sprite_index = start_looping_at.frame_index number_of_sprites,
                                              number_of_frames_to_show_each_sprite,
                                              does_sprite_loop

  # Now that we have `sprite_index, we can present the correct file.
  args.outputs.sprites << { x: 100,
                            y: 100,
                            w: 100,
                            h: 100,
                            path: "sprites/dragon_fly_#{sprite_index}.png" }

  # Try changing the numbers below to see how the animation changes:
  args.outputs.sprites << { x: 100,
                            y: 200,
                            w: 100,
                            h: 100,
                            path: "sprites/dragon_fly_#{0.frame_index 6, 4, true}.png" }
end

# This function shows how to animate a sprite that executes
# only once when the "f" key is pressed.
def one_time_animation args
  # This is just a label the shows instructions within the game.
  args.outputs.labels <<  { x: 220, y: 350, text: "(press f to animate)" }

  # If "f" is pressed on the keyboard...
  if args.inputs.keyboard.key_down.f
    # Print the frame that "f" was pressed on.
    puts "Hello from main.rb! The \"f\" key was in the down state on frame: #{args.state.tick_count}"

    # And MOST IMPORTANTLY set the point it time to start the animation,
    # equal to "now" which is represented as args.state.tick_count.

    # Also IMPORTANT, you'll notice that the value of when to start looping
    # is stored in `args.state`. This construct's values are retained across
    # executions of the `tick` method.
    args.state.start_looping_at = args.state.tick_count
  end

  # These are the same local variables that were defined
  # for the `looping_animation` function.
  number_of_sprites = 6
  number_of_frames_to_show_each_sprite = 4

  # Except this sprite does not loop again. If the animation time has passed,
  # then the frame_index function returns nil.
  does_sprite_loop = false

  if args.state.start_looping_at
    sprite_index = args.state
                       .start_looping_at
                       .frame_index number_of_sprites,
                                    number_of_frames_to_show_each_sprite,
                                    does_sprite_loop
  end

  # This line sets the frame index to zero, if
  # the animation duration has passed (frame_index returned nil).

  # Remeber: we are not looping forever here.
  sprite_index ||= 0

  # Present the sprite.
  args.outputs.sprites << { x: 100,
                            y: 300,
                            w: 100,
                            h: 100,
                            path: "sprites/dragon_fly_#{sprite_index}.png" }

  args.outputs.labels << { x: 640,
                           y: 700,
                           text: "Sample app shows how to use Numeric#frame_index to animate a sprite over time.",
                           anchor_x: 0.5,
                           anchor_y: 0.5 }
end

    Animation Using Sprite Sheet - main.rb link

    # ./samples/03_rendering_sprites/02_animation_using_sprite_sheet/app/main.rb
def tick args
  args.state.player ||= { x: 100,
                          y: 100,
                          w: 64,
                          h: 64,
                          direction: 1,
                          is_moving: false }

  # get the keyboard input and set player properties
  if args.inputs.keyboard.right
    args.state.player.x += 3
    args.state.player.direction = 1
    args.state.player.started_running_at ||= args.state.tick_count
  elsif args.inputs.keyboard.left
    args.state.player.x -= 3
    args.state.player.direction = -1
    args.state.player.started_running_at ||= args.state.tick_count
  end

  if args.inputs.keyboard.up
    args.state.player.y += 1
    args.state.player.started_running_at ||= args.state.tick_count
  elsif args.inputs.keyboard.down
    args.state.player.y -= 1
    args.state.player.started_running_at ||= args.state.tick_count
  end

  # if no arrow keys are being pressed, set the player as not moving
  if !args.inputs.keyboard.directional_vector
    args.state.player.started_running_at = nil
  end

  # wrap player around the stage
  if args.state.player.x > 1280
    args.state.player.x = -64
    args.state.player.started_running_at ||= args.state.tick_count
  elsif args.state.player.x < -64
    args.state.player.x = 1280
    args.state.player.started_running_at ||= args.state.tick_count
  end

  if args.state.player.y > 720
    args.state.player.y = -64
    args.state.player.started_running_at ||= args.state.tick_count
  elsif args.state.player.y < -64
    args.state.player.y = 720
    args.state.player.started_running_at ||= args.state.tick_count
  end

  # render player as standing or running
  if args.state.player.started_running_at
    args.outputs.sprites << running_sprite(args)
  else
    args.outputs.sprites << standing_sprite(args)
  end
  args.outputs.labels << [30, 700, "Use arrow keys to move around."]
end

def standing_sprite args
  {
    x: args.state.player.x,
    y: args.state.player.y,
    w: args.state.player.w,
    h: args.state.player.h,
    path: "sprites/horizontal-stand.png",
    flip_horizontally: args.state.player.direction > 0
  }
end

def running_sprite args
  if !args.state.player.started_running_at
    tile_index = 0
  else
    how_many_frames_in_sprite_sheet = 6
    how_many_ticks_to_hold_each_frame = 3
    should_the_index_repeat = true
    tile_index = args.state
                     .player
                     .started_running_at
                     .frame_index(how_many_frames_in_sprite_sheet,
                                  how_many_ticks_to_hold_each_frame,
                                  should_the_index_repeat)
  end

  {
    x: args.state.player.x,
    y: args.state.player.y,
    w: args.state.player.w,
    h: args.state.player.h,
    path: 'sprites/horizontal-run.png',
    tile_x: 0 + (tile_index * args.state.player.w),
    tile_y: 0,
    tile_w: args.state.player.w,
    tile_h: args.state.player.h,
    flip_horizontally: args.state.player.direction > 0
  }
end

    Animation States 1 - main.rb link

    # ./samples/03_rendering_sprites/03_animation_states_1/app/main.rb
class Game
  attr_gtk

  def defaults
    state.show_debug_layer = true if state.tick_count == 0

    state.player ||= {
      tile_size: 64,
      speed: 3,
      slash_frames: 15,
      x: 50,
      y: 400,
      dir_x: 1,
      dir_y: -1,
      is_moving: false
    }

    state.enemies ||= []
  end

  def add_enemy
    state.enemies << {
      x: 1200 * rand,
      y: 600 * rand,
      w: 64,
      h: 64,
      anchor_x: 0.5,
      anchor_y: 0.5,
      path: 'sprites/enemy.png'
    }
  end

  def sprite_horizontal_run
    tile_index = 0.frame_index(6, 3, true)
    tile_index = 0 if !player.is_moving

    {
      x: player.x,
      y: player.y,
      w: player.tile_size,
      h: player.tile_size,
      anchor_x: 0.5,
      anchor_y: 0.5,
      path: 'sprites/horizontal-run.png',
      tile_x: 0 + (tile_index * player.tile_size),
      tile_y: 0,
      tile_w: player.tile_size,
      tile_h: player.tile_size,
      flip_horizontally: player.dir_x > 0,
    }
  end

  def sprite_horizontal_stand
    {
      x: player.x,
      y: player.y,
      w: player.tile_size,
      h: player.tile_size,
      anchor_x: 0.5,
      anchor_y: 0.5,
      path: 'sprites/horizontal-stand.png',
      flip_horizontally: player.dir_x > 0,
    }
  end

  def sprite_horizontal_slash
    tile_index   = player.slash_at.frame_index(5, player.slash_frames.idiv(5), false) || 0

    {
      x: player.x + player.dir_x.sign * 9.25,
      y: player.y + 9.25,
      w: 165,
      h: 165,
      anchor_x: 0.5,
      anchor_y: 0.5,
      path: 'sprites/horizontal-slash.png',
      tile_x: 0 + (tile_index * 128),
      tile_y: 0,
      tile_w: 128,
      tile_h: 128,
      flip_horizontally: player.dir_x > 0
    }
  end

  def render_player
    if player.slash_at
      outputs.sprites << sprite_horizontal_slash
    elsif player.is_moving
      outputs.sprites << sprite_horizontal_run
    else
      outputs.sprites << sprite_horizontal_stand
    end
  end

  def render_enemies
    outputs.borders << state.enemies
  end

  def render_debug_layer
    return if !state.show_debug_layer
    outputs.borders << player.slash_collision_rect
  end

  def slash_initiate?
    inputs.controller_one.key_down.a || inputs.keyboard.key_down.j
  end

  def input
    # player movement
    if slash_complete? && (vector = inputs.directional_vector)
      player.x += vector.x * player.speed
      player.y += vector.y * player.speed
    end
    player.slash_at = slash_initiate? if slash_initiate?
  end

  def calc_movement
    # movement
    if vector = inputs.directional_vector
      state.debug_label = vector
      player.dir_x = vector.x if vector.x != 0
      player.dir_y = vector.y if vector.y != 0
      player.is_moving = true
    else
      state.debug_label = vector
      player.is_moving = false
    end
  end

  def calc_slash
    player.slash_collision_rect = {
      x: player.x + player.dir_x.sign * 52,
      y: player.y,
      w: 40,
      h: 20,
      anchor_x: 0.5,
      anchor_y: 0.5,
      path: "sprites/debug-slash.png"
    }

    # recalc sword's slash state
    player.slash_at = nil if slash_complete?

    # determine collision if the sword is at it's point of damaging
    return unless slash_can_damage?

    state.enemies.reject! { |e| e.intersect_rect? player.slash_collision_rect }
  end

  def slash_complete?
    !player.slash_at || player.slash_at.elapsed?(player.slash_frames)
  end

  def slash_can_damage?
    # damage occurs half way into the slash animation
    return false if slash_complete?
    return false if (player.slash_at + player.slash_frames.idiv(2)) != state.tick_count
    return true
  end

  def calc
    # generate an enemy if there aren't any on the screen
    add_enemy if state.enemies.length == 0
    calc_movement
    calc_slash
  end

  # source is at http://github.com/amirrajan/dragonruby-link-to-the-past
  def tick
    defaults
    render_enemies
    render_player
    outputs.labels << [30, 30, "Gamepad: D-Pad to move. B button to attack."]
    outputs.labels << [30, 52, "Keyboard: WASD/Arrow keys to move. J to attack."]
    render_debug_layer
    input
    calc
  end

  def player
    state.player
  end
end

$game = Game.new

def tick args
  $game.args = args
  $game.tick
end

$gtk.reset

    Animation States 2 - main.rb link

    # ./samples/03_rendering_sprites/03_animation_states_2/app/main.rb
def tick args
  defaults args
  input args
  calc args
  render args
end

def defaults args
  # uncomment the line below to slow the game down by a factor of 4 -> 15 fps (for debugging)
  # args.gtk.slowmo! 4

  args.state.player ||= {
    x: 144,                # render x of the player
    y: 32,                 # render y of the player
    w: 144 * 2,            # render width of the player
    h: 72 * 2,             # render height of the player
    dx: 0,                 # velocity x of the player
    action: :standing,     # current action/status of the player
    action_at: 0,          # frame that the action occurred
    previous_direction: 1, # direction the player was facing last frame
    direction: 1,          # direction the player is facing this frame
    launch_speed: 4,       # speed the player moves when they start running
    run_acceleration: 1,   # how much the player accelerates when running
    run_top_speed: 8,      # the top speed the player can run
    friction: 0.9,         # how much the player slows down when have stopped attempting to run
    anchor_x: 0.5,         # render anchor x of the player
    anchor_y: 0            # render anchor y of the player
  }
end

def input args
  # if the directional has been pressed on the input device
  if args.inputs.left_right != 0
    # determine if the player is currently running or not,
    # if they aren't, set their dx to their launch speed
    # otherwise, add the run acceleration to their dx
    if args.state.player.action != :running
      args.state.player.dx = args.state.player.launch_speed * args.inputs.left_right.sign
    else
      args.state.player.dx += args.inputs.left_right * args.state.player.run_acceleration
    end

    # capture the direction the player is facing and the previous direction
    args.state.player.previous_direction = args.state.player.direction
    args.state.player.direction = args.inputs.left_right.sign
  end
end

def calc args
  # clamp the player's dx to the top speed
  args.state.player.dx = args.state.player.dx.clamp(-args.state.player.run_top_speed, args.state.player.run_top_speed)

  # move the player by their dx
  args.state.player.x += args.state.player.dx

  # capture the player's hitbox
  player_hitbox = hitbox args.state.player

  # check boundary collisions and stop the player if they are colliding with the ednges of the screen
  if (player_hitbox.x - player_hitbox.w / 2) < 0
    args.state.player.x = player_hitbox.w / 2
    args.state.player.dx = 0
    # if the player is not standing, set them to standing and capture the frame
    if args.state.player.action != :standing
      args.state.player.action = :standing
      args.state.player.action_at = args.state.tick_count
    end
  elsif (player_hitbox.x + player_hitbox.w / 2) > 1280
    args.state.player.x = 1280 - player_hitbox.w / 2
    args.state.player.dx = 0

    # if the player is not standing, set them to standing and capture the frame
    if args.state.player.action != :standing
      args.state.player.action = :standing
      args.state.player.action_at = args.state.tick_count
    end
  end

  # if the player's dx is not 0, they are running. update their action and capture the frame if needed
  if args.state.player.dx.abs > 0
    if args.state.player.action != :running || args.state.player.direction != args.state.player.previous_direction
      args.state.player.action = :running
      args.state.player.action_at = args.state.tick_count
    end
  elsif args.inputs.left_right == 0
    # if the player's dx is 0 and they are not currently trying to run (left_right == 0), set them to standing and capture the frame
    if args.state.player.action != :standing
      args.state.player.action = :standing
      args.state.player.action_at = args.state.tick_count
    end
  end

  # if the player is not trying to run (left_right == 0), slow them down by the friction amount
  if args.inputs.left_right == 0
    args.state.player.dx *= args.state.player.friction

    # if the player's dx is less than 1, set it to 0
    if args.state.player.dx.abs < 1
      args.state.player.dx = 0
    end
  end
end

def render args
  # determine if the player should be flipped horizontally
  flip_horizontally = args.state.player.direction == -1
  # determine the path to the sprite to render, the idle sprite is used if action == :standing
  path = "sprites/link-idle.png"

  # if the player is running, determine the frame to render
  if args.state.player.action == :running
    # the sprite animation's first 3 frames represent the launch of the run, so we skip them on the animation loop
    # by setting the repeat_index to 3 (the 4th frame)
    frame_index = args.state.player.action_at.frame_index(count: 9, hold_for: 8, repeat: true, repeat_index: 3)
    path = "sprites/link-run-#{frame_index}.png"

    args.outputs.labels << { x: args.state.player.x - 144, y: args.state.player.y + 230, text: "action:      #{args.state.player.action}" }
    args.outputs.labels << { x: args.state.player.x - 144, y: args.state.player.y + 200, text: "action_at:   #{args.state.player.action_at}" }
    args.outputs.labels << { x: args.state.player.x - 144, y: args.state.player.y + 170, text: "frame_index: #{frame_index}" }
  else
    args.outputs.labels << { x: args.state.player.x - 144, y: args.state.player.y + 230, text: "action:      #{args.state.player.action}" }
    args.outputs.labels << { x: args.state.player.x - 144, y: args.state.player.y + 200, text: "action_at:   #{args.state.player.action_at}" }
    args.outputs.labels << { x: args.state.player.x - 144, y: args.state.player.y + 170, text: "frame_index: n/a" }
  end


  # render the player's hitbox and sprite (the hitbox is used to determine boundary collision)
  args.outputs.borders << hitbox(args.state.player)
  args.outputs.borders << args.state.player

  # render the player's sprite
  args.outputs.sprites << args.state.player.merge(path: path, flip_horizontally: flip_horizontally)
end

def hitbox entity
  {
    x: entity.x,
    y: entity.y + 5,
    w: 64,
    h: 96,
    anchor_x: 0.5,
    anchor_y: 0
  }
end


$gtk.reset

    Animation States 3 - main.rb link

    # ./samples/03_rendering_sprites/03_animation_states_3/app/main.rb
class Game
  attr_gtk

  def request_action name, at: nil
    at ||= state.tick_count
    state.player.requested_action = name
    state.player.requested_action_at = at
  end

  def defaults
    state.player.x                  ||= 64
    state.player.y                  ||= 0
    state.player.dx                 ||= 0
    state.player.dy                 ||= 0
    state.player.action             ||= :standing
    state.player.action_at          ||= 0
    state.player.next_action_queue  ||= {}
    state.player.facing             ||= 1
    state.player.jump_at            ||= 0
    state.player.jump_count         ||= 0
    state.player.max_speed          ||= 1.0
    state.sabre.x                   ||= state.player.x
    state.sabre.y                   ||= state.player.y
    state.actions_lookup            ||= new_actions_lookup
  end

  def render
    outputs.background_color = [32, 32, 32]
    outputs[:scene].transient!
    outputs[:scene].w = 128
    outputs[:scene].h = 128
    outputs[:scene].borders << { x: 0, y: 0, w: 128, h: 128, r: 255, g: 255, b: 255 }
    render_player
    render_sabre
    args.outputs.sprites << { x: 320, y: 0, w: 640, h: 640, path: :scene }
    args.outputs.labels << { x: 10, y: 100, text: "Controls:", r: 255, g: 255, b: 255, size_enum: -1 }
    args.outputs.labels << { x: 10, y: 80, text: "Move:   left/right", r: 255, g: 255, b: 255, size_enum: -1 }
    args.outputs.labels << { x: 10, y: 60, text: "Jump:   space | up | right click", r: 255, g: 255, b: 255, size_enum: -1 }
    args.outputs.labels << { x: 10, y: 40, text: "Attack: f     | j  | left click", r: 255, g: 255, b: 255, size_enum: -1 }
  end

  def render_sabre
    return if !state.sabre.is_active
    sabre_index = 0.frame_index count:    4,
                                hold_for: 2,
                                repeat:   true
    offset =  0
    offset = -8 if state.player.facing == -1
    outputs[:scene].sprites << { x: state.sabre.x + offset,
                        y: state.sabre.y, w: 16, h: 16, path: "sprites/sabre-throw/#{sabre_index}.png" }
  end

  def new_actions_lookup
    r = {
      slash_0: {
        frame_count: 6,
        interrupt_count: 4,
        path: "sprites/kenobi/slash-0/:index.png"
      },
      slash_1: {
        frame_count: 6,
        interrupt_count: 4,
        path: "sprites/kenobi/slash-1/:index.png"
      },
      throw_0: {
        frame_count: 8,
        throw_frame: 2,
        catch_frame: 6,
        path: "sprites/kenobi/slash-2/:index.png"
      },
      throw_1: {
        frame_count: 9,
        throw_frame: 2,
        catch_frame: 7,
        path: "sprites/kenobi/slash-3/:index.png"
      },
      throw_2: {
        frame_count: 9,
        throw_frame: 2,
        catch_frame: 7,
        path: "sprites/kenobi/slash-4/:index.png"
      },
      slash_5: {
        frame_count: 11,
        path: "sprites/kenobi/slash-5/:index.png"
      },
      slash_6: {
        frame_count: 8,
        interrupt_count: 6,
        path: "sprites/kenobi/slash-6/:index.png"
      }
    }

    r.each.with_index do |(k, v), i|
      v.name               ||= k
      v.index              ||= i

      v.hold_for           ||= 5
      v.duration           ||= v.frame_count * v.hold_for
      v.last_index         ||= v.frame_count - 1

      v.interrupt_count    ||= v.frame_count
      v.interrupt_duration ||= v.interrupt_count * v.hold_for

      v.repeat             ||= false
      v.next_action        ||= r[r.keys[i + 1]]
    end

    r
  end

  def render_player
    flip_horizontally = if state.player.facing == -1
                          true
                        else
                          false
                        end

    player_sprite = { x: state.player.x + 1 - 8,
                      y: state.player.y,
                      w: 16,
                      h: 16,
                      flip_horizontally: flip_horizontally }

    if state.player.action == :standing
      if state.player.y != 0
        if state.player.jump_count <= 1
          outputs[:scene].sprites << { **player_sprite, path: "sprites/kenobi/jumping.png" }
        else
          index = state.player.jump_at.frame_index count: 8, hold_for: 5, repeat: false
          index ||= 7
          outputs[:scene].sprites << { **player_sprite, path: "sprites/kenobi/second-jump/#{index}.png" }
        end
      elsif state.player.dx != 0
        index = state.player.action_at.frame_index count: 4, hold_for: 5, repeat: true
        outputs[:scene].sprites << { **player_sprite, path: "sprites/kenobi/run/#{index}.png" }
      else
        outputs[:scene].sprites << { **player_sprite, path: 'sprites/kenobi/standing.png'}
      end
    else
      v = state.actions_lookup[state.player.action]
      slash_frame_index = state.player.action_at.frame_index count:    v.frame_count,
                                                             hold_for: v.hold_for,
                                                             repeat:   v.repeat
      slash_frame_index ||= v.last_index
      slash_path          = v.path.sub ":index", slash_frame_index.to_s
      outputs[:scene].sprites << { **player_sprite, path: slash_path }
    end
  end

  def calc_input
    if state.player.next_action_queue.length > 2
      raise "Code in calc assums that key length of state.player.next_action_queue will never be greater than 2."
    end

    if inputs.controller_one.key_down.a ||
       inputs.mouse.button_left  ||
       inputs.keyboard.key_down.j ||
       inputs.keyboard.key_down.f
      request_action :attack
    end

    should_update_facing = false
    if state.player.action == :standing
      should_update_facing = true
    else
      key_0 = state.player.next_action_queue.keys[0]
      key_1 = state.player.next_action_queue.keys[1]
      if state.tick_count == key_0
        should_update_facing = true
      elsif state.tick_count == key_1
        should_update_facing = true
      elsif key_0 && key_1 && state.tick_count.between?(key_0, key_1)
        should_update_facing = true
      end
    end

    if should_update_facing && inputs.left_right.sign != state.player.facing.sign
      state.player.dx = 0

      if inputs.left
        state.player.facing = -1
      elsif inputs.right
        state.player.facing = 1
      end

      state.player.dx += 0.1 * inputs.left_right
    end

    if state.player.action == :standing
      state.player.dx += 0.1 * inputs.left_right
      if state.player.dx.abs > state.player.max_speed
        state.player.dx = state.player.max_speed * state.player.dx.sign
      end
    end

    was_jump_requested = inputs.keyboard.key_down.up ||
                         inputs.keyboard.key_down.w  ||
                         inputs.mouse.button_right  ||
                         inputs.controller_one.key_down.up ||
                         inputs.controller_one.key_down.b ||
                         inputs.keyboard.key_down.space

    can_jump = state.player.jump_at.elapsed_time > 20
    if state.player.jump_count <= 1
      can_jump = state.player.jump_at.elapsed_time > 10
    end

    if was_jump_requested && can_jump
      if state.player.action == :slash_6
        state.player.action = :standing
      end
      state.player.dy = 1
      state.player.jump_count += 1
      state.player.jump_at     = state.tick_count
    end
  end

  def calc
    calc_input
    calc_requested_action
    calc_next_action
    calc_sabre
    calc_player_movement

    if state.player.y <= 0 && state.player.dy < 0
      state.player.y = 0
      state.player.dy = 0
      state.player.jump_at = 0
      state.player.jump_count = 0
    end
  end

  def calc_player_movement
    state.player.x += state.player.dx
    state.player.y += state.player.dy
    state.player.dy -= 0.05
    if state.player.y <= 0
      state.player.y = 0
      state.player.dy = 0
      state.player.jump_at = 0
      state.player.jump_count = 0
    end

    if state.player.dx.abs < 0.09
      state.player.dx = 0
    end

    state.player.x = 8  if state.player.x < 8
    state.player.x = 120 if state.player.x > 120
  end

  def calc_requested_action
    return if !state.player.requested_action
    return if state.player.requested_action_at > state.tick_count

    player_action = state.player.action
    player_action_at = state.player.action_at

    # first attack
    if state.player.requested_action == :attack
      if player_action == :standing
        state.player.next_action_queue.clear
        state.player.next_action_queue[state.tick_count] = :slash_0
        state.player.next_action_queue[state.tick_count + state.actions_lookup.slash_0.duration] = :standing
      else
        current_action = state.actions_lookup[state.player.action]
        state.player.next_action_queue.clear
        queue_at = player_action_at + current_action.interrupt_duration
        queue_at = state.tick_count if queue_at < state.tick_count
        next_action = current_action.next_action
        next_action ||= { name: :standing,
                          duration: 4 }
        if next_action
        state.player.next_action_queue[queue_at] = next_action.name
        state.player.next_action_queue[player_action_at +
                                       current_action.interrupt_duration +
                                       next_action.duration] = :standing
        end
      end
    end

    state.player.requested_action = nil
    state.player.requested_action_at = nil
  end

  def calc_sabre
    can_throw_sabre = true
    sabre_throws = [:throw_0, :throw_1, :throw_2]
    if !sabre_throws.include? state.player.action
      state.sabre.facing = nil
      state.sabre.is_active = false
      return
    end

    current_action = state.actions_lookup[state.player.action]
    throw_at = state.player.action_at + (current_action.throw_frame) * 5
    catch_at = state.player.action_at + (current_action.catch_frame) * 5
    if !state.tick_count.between? throw_at, catch_at
      state.sabre.facing = nil
      state.sabre.is_active = false
      return
    end

    state.sabre.facing ||= state.player.facing

    state.sabre.is_active = true

    spline = [
      [  0, 0.25, 0.75, 1.0],
      [1.0, 0.75, 0.25,   0]
    ]

    throw_duration = catch_at - throw_at

    current_progress = args.easing.ease_spline throw_at,
                                               state.tick_count,
                                               throw_duration,
                                               spline

    farthest_sabre_x = 32
    state.sabre.y = state.player.y
    state.sabre.x = state.player.x + farthest_sabre_x * current_progress * state.sabre.facing
  end

  def calc_next_action
    return if !state.player.next_action_queue[state.tick_count]

    state.player.previous_action = state.player.action
    state.player.previous_action_at = state.player.action_at
    state.player.previous_action_ended_at = state.tick_count
    state.player.action = state.player.next_action_queue[state.tick_count]
    state.player.action_at = state.tick_count

    is_air_born = state.player.y != 0

    if state.player.action == :slash_0
      state.player.dy = 0 if state.player.dy > 0
      if is_air_born
        state.player.dy  = 0.5
      else
        state.player.dx += 0.25 * state.player.facing
      end
    elsif state.player.action == :slash_1
      state.player.dy = 0 if state.player.dy > 0
      if is_air_born
        state.player.dy  = 0.5
      else
        state.player.dx += 0.25 * state.player.facing
      end
    elsif state.player.action == :throw_0
      if is_air_born
        state.player.dy  = 1.0
      end

      state.player.dx += 0.5 * state.player.facing
    elsif state.player.action == :throw_1
      if is_air_born
        state.player.dy  = 1.0
      end

      state.player.dx += 0.5 * state.player.facing
    elsif state.player.action == :throw_2
      if is_air_born
        state.player.dy  = 1.0
      end

      state.player.dx += 0.5 * state.player.facing
    elsif state.player.action == :slash_5
      state.player.dy = 0 if state.player.dy < 0
      if is_air_born
        state.player.dy += 1.0
      else
        state.player.dy += 1.0
      end

      state.player.dx += 1.0 * state.player.facing
    elsif state.player.action == :slash_6
      state.player.dy = 0 if state.player.dy > 0
      if is_air_born
        state.player.dy  = -0.5
      end

      state.player.dx += 0.5 * state.player.facing
    end
  end

  def tick
    defaults
    calc
    render
  end
end

$game = Game.new

def tick args
  $game.args = args
  $game.tick
end

$gtk.reset

    Color And Rotation - main.rb link

    # ./samples/03_rendering_sprites/04_color_and_rotation/app/main.rb
=begin
 APIs listing that haven't been encountered in previous sample apps:

 - merge: Returns a hash containing the contents of two original hashes.
   Merge does not allow duplicate keys, so the value of a repeated key
   will be overwritten.

   For example, if we had two hashes
   h1 = { "a" => 1, "b" => 2}
   h2 = { "b" => 3, "c" => 3}
   and we called the command
   h1.merge(h2)
   the result would the following hash
   { "a" => 1, "b" => 3, "c" => 3}.

 Reminders:

 - Hashes: Collection of unique keys and their corresponding values. The value can be found
   using their keys.
   In this sample app, we're using a hash to create a sprite.

 - args.outputs.sprites: An array. The values generate a sprite.
   The parameters are [X, Y, WIDTH, HEIGHT, PATH, ANGLE, ALPHA, RED, GREEN, BLUE]
   Before continuing with this sample app, it is HIGHLY recommended that you look
   at mygame/documentation/05-sprites.md.

 - args.inputs.keyboard.key_held.KEY: Determines if a key is being pressed.
   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.

 - args.inputs.controller_one: Takes input from the controller based on what key is pressed.
   For more information about the controller, go to mygame/documentation/08-controllers.md.

 - num1.lesser(num2): Finds the lower value of the given options.

=end

# This sample app shows a car moving across the screen. It loops back around if it exceeds the dimensions of the screen,
# and also can be moved in different directions through keyboard input from the user.

# Calls the methods necessary for the game to run successfully.
def tick args
  default args
  render args.grid, args.outputs, args.state
  calc args.state
  process_inputs args
end

# Sets default values for the car sprite
# Initialization ||= only happens in the first frame
def default args
  args.state.sprite.width    = 19
  args.state.sprite.height   = 10
  args.state.sprite.scale    = 4
  args.state.max_speed       = 5
  args.state.x             ||= 100
  args.state.y             ||= 100
  args.state.speed         ||= 1
  args.state.angle         ||= 0
end

# Outputs sprite onto screen
def render grid, outputs, state
  outputs.background_color = [70, 70, 70]
  outputs.sprites <<  { **destination_rect(state), # sets first four parameters of car sprite
                        path: 'sprites/86.png',    # image path of car
                        angle: state.angle,
                        a: opacity,                # alpha
                        **saturation,
                        **source_rect(state),      # sprite sub division/tile (source x, y, w, h)
                        flip_horizontally: false,
                        flip_vertically: false,    # don't flip sprites
                        **rotation_anchor }
end

# Calls the calc_pos and calc_wrap methods.
def calc state
  calc_pos state
  calc_wrap state
end

# Changes sprite's position on screen
# Vectors have magnitude and direction, so the incremented x and y values give the car direction
def calc_pos state
  state.x     += state.angle.vector_x * state.speed # increments x by product of angle's x vector and speed
  state.y     += state.angle.vector_y * state.speed # increments y by product of angle's y vector and speed
  state.speed *= 1.1 # scales speed up
  state.speed  = state.speed.lesser(state.max_speed) # speed is either current speed or max speed, whichever has a lesser value (ensures that the car doesn't go too fast or exceed the max speed)
end

# The screen's dimensions are 1280x720. If the car goes out of scope,
# it loops back around on the screen.
def calc_wrap state

  # car returns to left side of screen if it disappears on right side of screen
  # sprite.width refers to tile's size, which is multipled by scale (4) to make it bigger
  state.x = -state.sprite.width * state.sprite.scale if state.x - 20 > 1280

  # car wraps around to right side of screen if it disappears on the left side
  state.x = 1280 if state.x + state.sprite.width * state.sprite.scale + 20 < 0

  # car wraps around to bottom of screen if it disappears at the top of the screen
  # if you subtract 520 pixels instead of 20 pixels, the car takes longer to reappear (try it!)
  state.y = 0    if state.y - 20 > 720 # if 20 pixels less than car's y position is greater than vertical scope

  # car wraps around to top of screen if it disappears at the bottom of the screen
  state.y = 720  if state.y + state.sprite.height * state.sprite.scale + 20 < 0
end

# Changes angle of sprite based on user input from keyboard or controller
def process_inputs args

  # NOTE: increasing the angle doesn't mean that the car will continue to go
  # in a specific direction. The angle is increasing, which means that if the
  # left key was kept in the "down" state, the change in the angle would cause
  # the car to go in a counter-clockwise direction and form a circle (360 degrees)
  if args.inputs.keyboard.key_held.left # if left key is pressed
    args.state.angle += 2 # car's angle is incremented by 2

  # The same applies to decreasing the angle. If the right key was kept in the
  # "down" state, the decreasing angle would cause the car to go in a clockwise
  # direction and form a circle (360 degrees)
  elsif args.inputs.keyboard.key_held.right # if right key is pressed
    args.state.angle -= 2 # car's angle is decremented by 2

  # Input from a controller can also change the angle of the car
  elsif args.inputs.controller_one.left_analog_x_perc != 0
    args.state.angle += 2 * args.inputs.controller_one.left_analog_x_perc * -1
  end
end

# A sprite's center of rotation can be altered
# Increasing either of these numbers would dramatically increase the
# car's drift when it turns!
def rotation_anchor
  { angle_anchor_x: 0.7, angle_anchor_y: 0.5 }
end

# Sets opacity value of sprite to 255 so that it is not transparent at all
# Change it to 0 and you won't be able to see the car sprite on the screen
def opacity
  255
end

# Sets the color of the sprite to white.
def saturation
  { r: 255, g: 255, b: 255 }
end

# Sets definition of destination_rect (used to define the car sprite)
def destination_rect state
  { x: state.x,
    y: state.y,
    w: state.sprite.width  * state.sprite.scale, # multiplies by 4 to set size
    h: state.sprite.height * state.sprite.scale }
end

# Portion of a sprite (a tile)
# Sub division of sprite is denoted as a rectangle directly related to original size of .png
# Tile is located at bottom left corner within a 19x10 pixel rectangle (based on sprite.width, sprite.height)
def source_rect state
  { source_x: 0,
    source_y: 0,
    source_w: state.sprite.width,
    source_h: state.sprite.height }
end

    Physics And Collisions link

    Simple - main.rb link

    # ./samples/04_physics_and_collisions/01_simple/app/main.rb
=begin

 Reminders:
 - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.

 - args.outputs.solids: An array. The values generate a solid.
   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]

=end

# This sample app shows collisions between two boxes.

# Runs methods needed for game to run properly.
def tick args
  tick_instructions args, "Sample app shows how to move a square over time and determine collision."
  defaults args
  render args
  calc args
end

# Sets default values.
def defaults args
  # These values represent the moving box.
  args.state.moving_box_speed   = 10
  args.state.moving_box_size    = 100
  args.state.moving_box_dx    ||=  1
  args.state.moving_box_dy    ||=  1
  args.state.moving_box       ||= [0, 0, args.state.moving_box_size, args.state.moving_box_size] # moving_box_size is set as the width and height

  # These values represent the center box.
  args.state.center_box ||= [540, 260, 200, 200, 180]
  args.state.center_box_collision ||= false # initially no collision
end

def render args
  # If the game state denotes that a collision has occured,
  # render a solid square, otherwise render a border instead.
  if args.state.center_box_collision
    args.outputs.solids << args.state.center_box
  else
    args.outputs.borders << args.state.center_box
  end

  # Then render the moving box.
  args.outputs.solids << args.state.moving_box
end

# Generally in a pipeline for a game engine, you have rendering,
# game simulation (calculation), and input processing.
# This fuction represents the game simulation.
def calc args
  position_moving_box args
  determine_collision_center_box args
end

# Changes the position of the moving box on the screen by multiplying the change in x (dx) and change in y (dy) by the speed,
# and adding it to the current position.
# dx and dy are positive if the box is moving right and up, respectively
# dx and dy are negative if the box is moving left and down, respectively
def position_moving_box args
  args.state.moving_box.x += args.state.moving_box_dx * args.state.moving_box_speed
  args.state.moving_box.y += args.state.moving_box_dy * args.state.moving_box_speed

  # 1280x720 are the virtual pixels you work with (essentially 720p).
  screen_width  = 1280
  screen_height = 720

  # Position of the box is denoted by the bottom left hand corner, in
  # that case, we have to subtract the width of the box so that it stays
  # in the scene (you can try deleting the subtraction to see how it
  # impacts the box's movement).
  if args.state.moving_box.x > screen_width - args.state.moving_box_size
    args.state.moving_box_dx = -1 # moves left
  elsif args.state.moving_box.x < 0
    args.state.moving_box_dx =  1 # moves right
  end

  # Here, we're making sure the moving box remains within the vertical scope of the screen
  if args.state.moving_box.y > screen_height - args.state.moving_box_size # if the box moves too high
    args.state.moving_box_dy = -1 # moves down
  elsif args.state.moving_box.y < 0 # if the box moves too low
    args.state.moving_box_dy =  1 # moves up
  end
end

def determine_collision_center_box args
  # Collision is handled by the engine. You simply have to call the
  # `intersect_rect?` function.
  if args.state.moving_box.intersect_rect? args.state.center_box # if the two boxes intersect
    args.state.center_box_collision = true # then a collision happened
  else
    args.state.center_box_collision = false # otherwise, no collision happened
  end
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Simple Aabb Collision - main.rb link

    # ./samples/04_physics_and_collisions/01_simple_aabb_collision/app/main.rb
def tick args
  # define terrain of 32x32 sized squares
  args.state.terrain ||= [
    { x: 640,          y: 360,          w: 32, h: 32, path: 'sprites/square/blue.png' },
    { x: 640,          y: 360 - 32,     w: 32, h: 32, path: 'sprites/square/blue.png' },
    { x: 640,          y: 360 - 32 * 2, w: 32, h: 32, path: 'sprites/square/blue.png' },
    { x: 640 + 32,     y: 360 - 32 * 2, w: 32, h: 32, path: 'sprites/square/blue.png' },
    { x: 640 + 32 * 2, y: 360 - 32 * 2, w: 32, h: 32, path: 'sprites/square/blue.png' },
  ]

  # define player
  args.state.player ||= {
    x: 600,
    y: 360,
    w: 32,
    h: 32,
    dx: 0,
    dy: 0,
    path: 'sprites/square/red.png'
  }

  # render terrain and player
  args.outputs.sprites << args.state.terrain
  args.outputs.sprites << args.state.player

  # set dx and dy based on inputs
  args.state.player.dx = args.inputs.left_right * 2
  args.state.player.dy = args.inputs.up_down * 2

  # check for collisions on the x and y axis independently

  # increment the player's position by dx
  args.state.player.x += args.state.player.dx

  # check for collision on the x axis first
  collision = args.state.terrain.find { |t| t.intersect_rect? args.state.player }

  # if there is a collision, move the player to the edge of the collision
  # based on the direction of the player's movement and set the player's
  # dx to 0
  if collision
    if args.state.player.dx > 0
      args.state.player.x = collision.x - args.state.player.w
    elsif args.state.player.dx < 0
      args.state.player.x = collision.x + collision.w
    end
    args.state.player.dx = 0
  end

  # increment the player's position by dy
  args.state.player.y += args.state.player.dy

  # check for collision on the y axis next
  collision = args.state.terrain.find { |t| t.intersect_rect? args.state.player }

  # if there is a collision, move the player to the edge of the collision
  # based on the direction of the player's movement and set the player's
  # dy to 0
  if collision
    if args.state.player.dy > 0
      args.state.player.y = collision.y - args.state.player.h
    elsif args.state.player.dy < 0
      args.state.player.y = collision.y + collision.h
    end
    args.state.player.dy = 0
  end
end

    Simple Aabb Collision With Map Editor - main.rb link

    # ./samples/04_physics_and_collisions/01_simple_aabb_collision_with_map_editor/app/main.rb
# the sample app is an expansion of ./01_simple_aabb_collision
# but includes an in game map editor that saves map data to disk
def tick args
  # if it's the first tick, read the terrain data from disk
  # and create the player
  if args.state.tick_count == 0
    args.state.terrain = read_terrain_data args

    args.state.player = {
      x: 320,
      y: 320,
      w: 32,
      h: 32,
      dx: 0,
      dy: 0,
      path: 'sprites/square/red.png'
    }
  end

  # tick the game (where input and aabb collision is processed)
  tick_game args

  # tick the map editor
  tick_map_editor args
end

def tick_game args
  # render terrain and player
  args.outputs.sprites << args.state.terrain
  args.outputs.sprites << args.state.player

  # set dx and dy based on inputs
  args.state.player.dx = args.inputs.left_right * 2
  args.state.player.dy = args.inputs.up_down * 2

  # check for collisions on the x and y axis independently

  # increment the player's position by dx
  args.state.player.x += args.state.player.dx

  # check for collision on the x axis first
  collision = args.state.terrain.find { |t| t.intersect_rect? args.state.player }

  # if there is a collision, move the player to the edge of the collision
  # based on the direction of the player's movement and set the player's
  # dx to 0
  if collision
    if args.state.player.dx > 0
      args.state.player.x = collision.x - args.state.player.w
    elsif args.state.player.dx < 0
      args.state.player.x = collision.x + collision.w
    end
    args.state.player.dx = 0
  end

  # increment the player's position by dy
  args.state.player.y += args.state.player.dy

  # check for collision on the y axis next
  collision = args.state.terrain.find { |t| t.intersect_rect? args.state.player }

  # if there is a collision, move the player to the edge of the collision
  # based on the direction of the player's movement and set the player's
  # dy to 0
  if collision
    if args.state.player.dy > 0
      args.state.player.y = collision.y - args.state.player.h
    elsif args.state.player.dy < 0
      args.state.player.y = collision.y + collision.h
    end
    args.state.player.dy = 0
  end
end

def tick_map_editor args
  # determine the location of the mouse, but
  # aligned to the grid
  grid_aligned_mouse_rect = {
    x: args.inputs.mouse.x.idiv(32) * 32,
    y: args.inputs.mouse.y.idiv(32) * 32,
    w: 32,
    h: 32
  }

  # determine if there's a tile at the grid aligned mouse location
  existing_terrain = args.state.terrain.find { |t| t.intersect_rect? grid_aligned_mouse_rect }

  # if there is, then render a red square to denote that
  # the tile will be deleted
  if existing_terrain
    args.outputs.sprites << {
      x: args.inputs.mouse.x.idiv(32) * 32,
      y: args.inputs.mouse.y.idiv(32) * 32,
      w: 32,
      h: 32,
      path: "sprites/square/red.png",
      a: 128
    }
  else
    # otherwise, render a blue square to denote that
    # a tile will be added
    args.outputs.sprites << {
      x: args.inputs.mouse.x.idiv(32) * 32,
      y: args.inputs.mouse.y.idiv(32) * 32,
      w: 32,
      h: 32,
      path: "sprites/square/blue.png",
      a: 128
    }
  end

  # if the mouse is clicked, then add or remove a tile
  if args.inputs.mouse.click
    if existing_terrain
      args.state.terrain.delete existing_terrain
    else
      args.state.terrain << { **grid_aligned_mouse_rect, path: "sprites/square/blue.png" }
    end

    # once the terrain state has been updated
    # save the terrain data to disk
    write_terrain_data args
  end
end

def read_terrain_data args
  # create the terrain data file if it doesn't exist
  contents = args.gtk.read_file "data/terrain.txt"
  if !contents
    args.gtk.write_file "data/terrain.txt", ""
  end

  # read the terrain data from disk which is a csv
  args.gtk.read_file('data/terrain.txt').split("\n").map do |line|
    x, y, w, h = line.split(',').map(&:to_i)
    { x: x, y: y, w: w, h: h, path: 'sprites/square/blue.png' }
  end
end

def write_terrain_data args
  terrain_csv = args.state.terrain.map { |t| "#{t.x},#{t.y},#{t.w},#{t.h}" }.join "\n"
  args.gtk.write_file 'data/terrain.txt', terrain_csv
end

    Simple Aabb Collision With Map Editor - Data - terrain.txt link

    # ./samples/04_physics_and_collisions/01_simple_aabb_collision_with_map_editor/data/terrain.txt
352,320,32,32
352,352,32,32
352,384,32,32
352,256,32,32
352,192,32,32
352,224,32,32

    Moving Objects - main.rb link

    # ./samples/04_physics_and_collisions/02_moving_objects/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - Hashes: Collection of unique keys and their corresponding values. The value can be found
   using their keys.

   For example, if we have a "numbers" hash that stores numbers in English as the
   key and numbers in Spanish as the value, we'd have a hash that looks like this...
   numbers = { "one" => "uno", "two" => "dos", "three" => "tres" }
   and on it goes.

   Now if we wanted to find the corresponding value of the "one" key, we could say
   puts numbers["one"]
   which would print "uno" to the console.

 - num1.greater(num2): Returns the greater value.
   For example, if we have the command
   puts 4.greater(3)
   the number 4 would be printed to the console since it has a greater value than 3.
   Similar to lesser, which returns the lesser value.

 - num1.lesser(num2): Finds the lower value of the given options.
   For example, in the statement
   a = 4.lesser(3)
   3 has a lower value than 4, which means that the value of a would be set to 3,
   but if the statement had been
   a = 4.lesser(5)
   4 has a lower value than 5, which means that the value of a would be set to 4.

 - reject: Removes elements from a collection if they meet certain requirements.
   For example, you can derive an array of odd numbers from an original array of
   numbers 1 through 10 by rejecting all elements that are even (or divisible by 2).

 - find_all: Finds all values that satisfy specific requirements.
   For example, you can find all elements of a collection that are divisible by 2
   or find all objects that have intersected with another object.

 - abs: Returns the absolute value.
   For example, the command
   (-30).abs
   would return 30 as a result.

 - map: Ruby method used to transform data; used in arrays, hashes, and collections.
   Can be used to perform an action on every element of a collection, such as multiplying
   each element by 2 or declaring every element as a new entity.

 Reminders:

 - args.inputs.keyboard.KEY: Determines if a key has been pressed.
   For more information about the keyboard, take a look at mygame/documentation/06-keyboard.md.

 - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.

 - args.outputs.solids: An array. The values generate a solid.
   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.

=end

# Calls methods needed for game to run properly
def tick args
  tick_instructions args, "Use LEFT and RIGHT arrow keys to move and SPACE to jump."
  defaults args
  render args
  calc args
  input args
end

# sets default values and creates empty collections
# initialization only happens in the first frame
def defaults args
  fiddle args
  args.state.enemy.hammers ||= []
  args.state.enemy.hammer_queue ||= []
  args.state.tick_count = args.state.tick_count
  args.state.bridge_top = 128
  args.state.player.x  ||= 0                        # initializes player's properties
  args.state.player.y  ||= args.state.bridge_top
  args.state.player.w  ||= 64
  args.state.player.h  ||= 64
  args.state.player.dy ||= 0
  args.state.player.dx ||= 0
  args.state.enemy.x   ||= 800                      # initializes enemy's properties
  args.state.enemy.y   ||= 0
  args.state.enemy.w   ||= 128
  args.state.enemy.h   ||= 128
  args.state.enemy.dy  ||= 0
  args.state.enemy.dx  ||= 0
  args.state.game_over_at ||= 0
end

# sets enemy, player, hammer values
def fiddle args
  args.state.gravity                     = -0.3
  args.state.enemy_jump_power            = 10       # sets enemy values
  args.state.enemy_jump_interval         = 60
  args.state.hammer_throw_interval       = 40       # sets hammer values
  args.state.hammer_launch_power_default = 5
  args.state.hammer_launch_power_near    = 2
  args.state.hammer_launch_power_far     = 7
  args.state.hammer_upward_launch_power  = 15
  args.state.max_hammers_per_volley      = 10
  args.state.gap_between_hammers         = 10
  args.state.player_jump_power           = 10       # sets player values
  args.state.player_jump_power_duration  = 10
  args.state.player_max_run_speed        = 10
  args.state.player_speed_slowdown_rate  = 0.9
  args.state.player_acceleration         = 1
  args.state.hammer_size                 = 32
end

# outputs objects onto the screen
def render args
  args.outputs.solids << 20.map_with_index do |i| # uses 20 squares to form bridge
    # sets x by multiplying 64 to index to find pixel value (places all squares side by side)
    # subtracts 64 from bridge_top because position is denoted by bottom left corner
    [i * 64, args.state.bridge_top - 64, 64, 64]
  end

  args.outputs.solids << [args.state.x, args.state.y, args.state.w, args.state.h, 255, 0, 0]
  args.outputs.solids << [args.state.player.x, args.state.player.y, args.state.player.w, args.state.player.h, 255, 0, 0] # outputs player onto screen (red box)
  args.outputs.solids << [args.state.enemy.x, args.state.enemy.y, args.state.enemy.w, args.state.enemy.h, 0, 255, 0] # outputs enemy onto screen (green box)
  args.outputs.solids << args.state.enemy.hammers # outputs enemy's hammers onto screen
end

# Performs calculations to move objects on the screen
def calc args

  # Since velocity is the change in position, the change in x increases by dx. Same with y and dy.
  args.state.player.x  += args.state.player.dx
  args.state.player.y  += args.state.player.dy

  # Since acceleration is the change in velocity, the change in y (dy) increases every frame
  args.state.player.dy += args.state.gravity

  # player's y position is either current y position or y position of top of
  # bridge, whichever has a greater value
  # ensures that the player never goes below the bridge
  args.state.player.y  = args.state.player.y.greater(args.state.bridge_top)

  # player's x position is either the current x position or 0, whichever has a greater value
  # ensures that the player doesn't go too far left (out of the screen's scope)
  args.state.player.x  = args.state.player.x.greater(0)

  # player is not falling if it is located on the top of the bridge
  args.state.player.falling = false if args.state.player.y == args.state.bridge_top
  args.state.player.rect = [args.state.player.x, args.state.player.y, args.state.player.h, args.state.player.w] # sets definition for player

  args.state.enemy.x += args.state.enemy.dx # velocity; change in x increases by dx
  args.state.enemy.y += args.state.enemy.dy # same with y and dy

  # ensures that the enemy never goes below the bridge
  args.state.enemy.y  = args.state.enemy.y.greater(args.state.bridge_top)

  # ensures that the enemy never goes too far left (outside the screen's scope)
  args.state.enemy.x  = args.state.enemy.x.greater(0)

  # objects that go up must come down because of gravity
  args.state.enemy.dy += args.state.gravity

  args.state.enemy.y  = args.state.enemy.y.greater(args.state.bridge_top)

  #sets definition of enemy
  args.state.enemy.rect = [args.state.enemy.x, args.state.enemy.y, args.state.enemy.h, args.state.enemy.w]

  if args.state.enemy.y == args.state.bridge_top # if enemy is located on the top of the bridge
    args.state.enemy.dy = 0 # there is no change in y
  end

  # if 60 frames have passed and the enemy is not moving vertically
  if args.state.tick_count.mod_zero?(args.state.enemy_jump_interval) && args.state.enemy.dy == 0
    args.state.enemy.dy = args.state.enemy_jump_power # the enemy jumps up
  end

  # if 40 frames have passed or 5 frames have passed since the game ended
  if args.state.tick_count.mod_zero?(args.state.hammer_throw_interval) || args.state.game_over_at.elapsed_time == 5
    # rand will return a number greater than or equal to 0 and less than given variable's value (since max is excluded)
    # that is why we're adding 1, to include the max possibility
    volley_dx   = (rand(args.state.hammer_launch_power_default) + 1) * -1 # horizontal movement (follow order of operations)

    # if the horizontal distance between the player and enemy is less than 128 pixels
    if (args.state.player.x - args.state.enemy.x).abs < 128
      # the change in x won't be that great since the enemy and player are closer to each other
      volley_dx = (rand(args.state.hammer_launch_power_near) + 1) * -1
    end

    # if the horizontal distance between the player and enemy is greater than 300 pixels
    if (args.state.player.x - args.state.enemy.x).abs > 300
      # change in x will be more drastic since player and enemy are so far apart
      volley_dx = (rand(args.state.hammer_launch_power_far) + 1) * -1 # more drastic change
    end

    (rand(args.state.max_hammers_per_volley) + 1).map_with_index do |i|
      args.state.enemy.hammer_queue << { # stores hammer values in a hash
        x: args.state.enemy.x,
        w: args.state.hammer_size,
        h: args.state.hammer_size,
        dx: volley_dx, # change in horizontal position
        # multiplication operator takes precedence over addition operator
        throw_at: args.state.tick_count + i * args.state.gap_between_hammers
      }
    end
  end

  # add elements from hammer_queue collection to the hammers collection by
  # finding all hammers that were thrown before the current frame (have already been thrown)
  args.state.enemy.hammers += args.state.enemy.hammer_queue.find_all do |h|
    h[:throw_at] < args.state.tick_count
  end

  args.state.enemy.hammers.each do |h| # sets values for all hammers in collection
    h[:y]  ||= args.state.enemy.y + 130
    h[:dy] ||= args.state.hammer_upward_launch_power
    h[:dy]  += args.state.gravity # acceleration is change in gravity
    h[:x]   += h[:dx] # incremented by change in position
    h[:y]   += h[:dy]
    h[:rect] = [h[:x], h[:y], h[:w], h[:h]] # sets definition of hammer's rect
  end

  # reject hammers that have been thrown before current frame (have already been thrown)
  args.state.enemy.hammer_queue = args.state.enemy.hammer_queue.reject do |h|
    h[:throw_at] < args.state.tick_count
  end

  # any hammers with a y position less than 0 are rejected from the hammers collection
  # since they have gone too far down (outside the scope's screen)
  args.state.enemy.hammers = args.state.enemy.hammers.reject { |h| h[:y] < 0 }

  # if there are any hammers that intersect with (or hit) the player,
  # the reset_player method is called (so the game can start over)
  if args.state.enemy.hammers.any? { |h| h[:rect].intersect_rect?(args.state.player.rect) }
    reset_player args
  end

  # if the enemy's rect intersects with (or hits) the player,
  # the reset_player method is called (so the game can start over)
  if args.state.enemy.rect.intersect_rect? args.state.player.rect
    reset_player args
  end
end

# Resets the player by changing its properties back to the values they had at initialization
def reset_player args
  args.state.player.x = 0
  args.state.player.y = args.state.bridge_top
  args.state.player.dy = 0
  args.state.player.dx = 0
  args.state.enemy.hammers.clear # empties hammer collection
  args.state.enemy.hammer_queue.clear # empties hammer_queue
  args.state.game_over_at = args.state.tick_count # game_over_at set to current frame (or passage of time)
end

# Processes input from the user to move the player
def input args
  if args.inputs.keyboard.space # if the user presses the space bar
    args.state.player.jumped_at ||= args.state.tick_count # jumped_at is set to current frame

    # if the time that has passed since the jump is less than the player's jump duration and
    # the player is not falling
    if args.state.player.jumped_at.elapsed_time < args.state.player_jump_power_duration && !args.state.player.falling
      args.state.player.dy = args.state.player_jump_power # change in y is set to power of player's jump
    end
  end

  # if the space bar is in the "up" state (or not being pressed down)
  if args.inputs.keyboard.key_up.space
    args.state.player.jumped_at = nil # jumped_at is empty
    args.state.player.falling = true # the player is falling
  end

  if args.inputs.keyboard.left # if left key is pressed
    args.state.player.dx -= args.state.player_acceleration # dx decreases by acceleration (player goes left)
    # dx is either set to current dx or the negative max run speed (which would be -10),
    # whichever has a greater value
    args.state.player.dx = args.state.player.dx.greater(-args.state.player_max_run_speed)
  elsif args.inputs.keyboard.right # if right key is pressed
    args.state.player.dx += args.state.player_acceleration # dx increases by acceleration (player goes right)
    # dx is either set to current dx or max run speed (which would be 10),
    # whichever has a lesser value
    args.state.player.dx = args.state.player.dx.lesser(args.state.player_max_run_speed)
  else
    args.state.player.dx *= args.state.player_speed_slowdown_rate # dx is scaled down
  end
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.space ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Entities - main.rb link

    # ./samples/04_physics_and_collisions/03_entities/app/main.rb
=begin

 Reminders:

 - map: Ruby method used to transform data; used in arrays, hashes, and collections.
   Can be used to perform an action on every element of a collection, such as multiplying
   each element by 2 or declaring every element as a new entity.

 - reject: Removes elements from a collection if they meet certain requirements.
   For example, you can derive an array of odd numbers from an original array of
   numbers 1 through 10 by rejecting all elements that are even (or divisible by 2).

 - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
   In this sample app, new_entity is used to define the properties of enemies and bullets.
   (Remember, you can use state to define ANY property and it will be retained across frames.)

 - args.outputs.labels: An array. The values generate a label on the screen.
   The parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]

 - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.

 - args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.

=end

# This sample app shows enemies that contain an id value and the time they were created.
# These enemies can be removed by shooting at them with bullets.

# Calls all methods necessary for the game to function properly.
def tick args
  tick_instructions args, "Sample app shows how to use args.state.new_entity along with collisions. CLICK to shoot a bullet."
  defaults args
  render args
  calc args
  process_inputs args
end

# Sets default values
# Enemies and bullets start off as empty collections
def defaults args
  args.state.enemies ||= []
  args.state.bullets ||= []
end

# Provides each enemy in enemies collection with rectangular border,
# as well as a label showing id and when they were created
def render args
  # When you're calling a method that takes no arguments, you can use this & syntax on map.
  # Numbers are being added to x and y in order to keep the text within the enemy's borders.
  args.outputs.borders << args.state.enemies.map(&:rect)
  args.outputs.labels  << args.state.enemies.flat_map do |enemy|
    [
      [enemy.x + 4, enemy.y + 29, "id: #{enemy.entity_id}", -3, 0],
      [enemy.x + 4, enemy.y + 17, "created_at: #{enemy.created_at}", -3, 0] # frame enemy was created
    ]
  end

  # Outputs bullets in bullets collection as rectangular solids
  args.outputs.solids << args.state.bullets.map(&:rect)
end

# Calls all methods necessary for performing calculations
def calc args
  add_new_enemies_if_needed args
  move_bullets args
  calculate_collisions args
  remove_bullets_of_screen args
end

# Adds enemies to the enemies collection and sets their values
def add_new_enemies_if_needed args
  return if args.state.enemies.length >= 10 # if 10 or more enemies, enemies are not added
  return unless args.state.bullets.length == 0 # if user has not yet shot bullet, no enemies are added

  args.state.enemies += (10 - args.state.enemies.length).map do # adds enemies so there are 10 total
    args.state.new_entity(:enemy) do |e| # each enemy is declared as a new entity
      e.x = 640 + 500 * rand # each enemy is given random position on screen
      e.y = 600 * rand + 50
      e.rect = [e.x, e.y, 130, 30] # sets definition for enemy's rect
    end
  end
end

# Moves bullets across screen
# Sets definition of the bullets
def move_bullets args
  args.state.bullets.each do |bullet| # perform action on each bullet in collection
    bullet.x += bullet.speed # increment x by speed (bullets fly horizontally across screen)

    # By randomizing the value that increments bullet.y, the bullet does not fly straight up and out
    # of the scope of the screen. Try removing what follows bullet.speed, or changing 0.25 to 1.25 to
    # see what happens to the bullet's movement.
    bullet.y += bullet.speed.*(0.25).randomize(:ratio, :sign)
    bullet.rect = [bullet.x, bullet.y, bullet.size, bullet.size] # sets definition of bullet's rect
  end
end

# Determines if a bullet hits an enemy
def calculate_collisions args
  args.state.bullets.each do |bullet| # perform action on every bullet and enemy in collections
    args.state.enemies.each do |enemy|
      # if bullet has not exploded yet and the bullet hits an enemy
      if !bullet.exploded && bullet.rect.intersect_rect?(enemy.rect)
        bullet.exploded = true # bullet explodes
        enemy.dead = true # enemy is killed
      end
    end
  end

  # All exploded bullets are rejected or removed from the bullets collection
  # and any dead enemy is rejected from the enemies collection.
  args.state.bullets = args.state.bullets.reject(&:exploded)
  args.state.enemies = args.state.enemies.reject(&:dead)
end

# Bullets are rejected from bullets collection once their position exceeds the width of screen
def remove_bullets_of_screen args
  args.state.bullets = args.state.bullets.reject { |bullet| bullet.x > 1280 } # screen width is 1280
end

# Calls fire_bullet method
def process_inputs args
  fire_bullet args
end

# Once mouse is clicked by the user to fire a bullet, a new bullet is added to bullets collection
def fire_bullet args
  return unless args.inputs.mouse.click # return unless mouse is clicked
  args.state.bullets << args.state.new_entity(:bullet) do |bullet| # new bullet is declared a new entity
    bullet.y = args.inputs.mouse.click.point.y # set to the y value of where the mouse was clicked
    bullet.x = 0 # starts on the left side of the screen
    bullet.size = 10
    bullet.speed = 10 * rand + 2 # speed of a bullet is randomized
    bullet.rect = [bullet.x, bullet.y, bullet.size, bullet.size] # definition is set
  end
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.space ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Box Collision - main.rb link

    # ./samples/04_physics_and_collisions/04_box_collision/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - first: Returns the first element of the array.
   For example, if we have an array
   numbers = [1, 2, 3, 4, 5]
   and we call first by saying
   numbers.first
   the number 1 will be returned because it is the first element of the numbers array.

 - num1.idiv(num2): Divides two numbers and returns an integer.
   For example,
   16.idiv(3) = 5, because 16 / 3 is 5.33333 returned as an integer.
   16.idiv(4) = 4, because 16 / 4 is 4 and already has no decimal.

 Reminders:

 - find_all: Finds all values that satisfy specific requirements.

 - ARRAY#intersect_rect?: An array with at least four values is
   considered a rect. The intersect_rect? function returns true
   or false depending on if the two rectangles intersect.

 - reject: Removes elements from a collection if they meet certain requirements.

=end

# This sample app allows users to create tiles and place them anywhere on the screen as obstacles.
# The player can then move and maneuver around them.

class PoorManPlatformerPhysics
  attr_accessor :grid, :inputs, :state, :outputs

  # Calls all methods necessary for the app to run successfully.
  def tick
    defaults
    render
    calc
    process_inputs
  end

  # Sets default values for variables.
  # The ||= sign means that the variable will only be set to the value following the = sign if the value has
  # not already been set before. Intialization happens only in the first frame.
  def defaults
    state.tile_size               = 64
    state.gravity                 = -0.2
    state.previous_tile_size    ||= state.tile_size
    state.x                     ||= 0
    state.y                     ||= 800
    state.dy                    ||= 0
    state.dx                    ||= 0
    state.world                 ||= []
    state.world_lookup          ||= {}
    state.world_collision_rects ||= []
  end

  # Outputs solids and borders of different colors for the world and collision_rects collections.
  def render

    # Sets a black background on the screen (Comment this line out and the background will become white.)
    # Also note that black is the default color for when no color is assigned.
    outputs.solids << grid.rect

    # The position, size, and color (white) are set for borders given to the world collection.
    # Try changing the color by assigning different numbers (between 0 and 255) to the last three parameters.
    outputs.borders << state.world.map do |x, y|
      [x * state.tile_size,
       y * state.tile_size,
       state.tile_size,
       state.tile_size, 255, 255, 255]
    end

    # The top, bottom, and sides of the borders for collision_rects are different colors.
    outputs.borders << state.world_collision_rects.map do |e|
      [
        [e[:top],                             0, 170,   0], # top is a shade of green
        [e[:bottom],                          0, 100, 170], # bottom is a shade of greenish-blue
        [e[:left_right],                    170,   0,   0], # left and right are a shade of red
      ]
    end

    # Sets the position, size, and color (a shade of green) of the borders of only the player's
    # box and outputs it. If you change the 180 to 0, the player's box will be black and you
    # won't be able to see it (because it will match the black background).
    outputs.borders << [state.x,
                        state.y,
                        state.tile_size,
                        state.tile_size,  0, 180, 0]
  end

  # Calls methods needed to perform calculations.
  def calc
    calc_world_lookup
    calc_player
  end

  # Performs calculations on world_lookup and sets values.
  def calc_world_lookup

    # If the tile size isn't equal to the previous tile size,
    # the previous tile size is set to the tile size,
    # and world_lookup hash is set to empty.
    if state.tile_size != state.previous_tile_size
      state.previous_tile_size = state.tile_size
      state.world_lookup = {} # empty hash
    end

    # return if the world_lookup hash has keys (or, in other words, is not empty)
    # return unless the world collection has values inside of it (or is not empty)
    return if state.world_lookup.keys.length > 0
    return unless state.world.length > 0

    # Starts with an empty hash for world_lookup.
    # Searches through the world and finds the coordinates that exist.
    state.world_lookup = {}
    state.world.each { |x, y| state.world_lookup[[x, y]] = true }

    # Assigns world_collision_rects for every sprite drawn.
    state.world_collision_rects =
      state.world_lookup
          .keys
          .map do |coord_x, coord_y|
            s = state.tile_size
            # multiply by tile size so the grid coordinates; sets pixel value
            # don't forget that position is denoted by bottom left corner
            # set x = coord_x or y = coord_y and see what happens!
            x = s * coord_x
            y = s * coord_y
            {
              # The values added to x, y, and s position the world_collision_rects so they all appear
              # stacked (on top of world rects) but don't directly overlap.
              # Remove these added values and mess around with the rect placement!
              args:       [coord_x, coord_y],
              left_right: [x,     y + 4, s,     s - 6], # hash keys and values
              top:        [x + 4, y + 6, s - 8, s - 6],
              bottom:     [x + 1, y - 1, s - 2, s - 8],
            }
          end
  end

  # Performs calculations to change the x and y values of the player's box.
  def calc_player

    # Since acceleration is the change in velocity, the change in y (dy) increases every frame.
    # What goes up must come down because of gravity.
    state.dy += state.gravity

    # Calls the calc_box_collision and calc_edge_collision methods.
    calc_box_collision
    calc_edge_collision

    # Since velocity is the change in position, the change in y increases by dy. Same with x and dx.
    state.y += state.dy
    state.x += state.dx

    # Scales dx down.
    state.dx *= 0.8
  end

  # Calls methods needed to determine collisions between player and world_collision rects.
  def calc_box_collision
    return unless state.world_lookup.keys.length > 0 # return unless hash has atleast 1 key
    collision_floor!
    collision_left!
    collision_right!
    collision_ceiling!
  end

  # Finds collisions between the bottom of the player's rect and the top of a world_collision_rect.
  def collision_floor!
    return unless state.dy <= 0 # return unless player is going down or is as far down as possible
    player_rect = [state.x, state.y - 0.1, state.tile_size, state.tile_size] # definition of player

    # Goes through world_collision_rects to find all intersections between the bottom of player's rect and
    # the top of a world_collision_rect (hence the "-0.1" above)
    floor_collisions = state.world_collision_rects
                           .find_all { |r| r[:top].intersect_rect?(player_rect, collision_tollerance) }
                           .first

    return unless floor_collisions # return unless collision occurred
    state.y = floor_collisions[:top].top # player's y is set to the y of the top of the collided rect
    state.dy = 0 # if a collision occurred, the player's rect isn't moving because its path is blocked
  end

  # Finds collisions between the player's left side and the right side of a world_collision_rect.
  def collision_left!
    return unless state.dx < 0 # return unless player is moving left
    player_rect = [state.x - 0.1, state.y, state.tile_size, state.tile_size]

    # Goes through world_collision_rects to find all intersections beween the player's left side and the
    # right side of a world_collision_rect.
    left_side_collisions = state.world_collision_rects
                               .find_all { |r| r[:left_right].intersect_rect?(player_rect, collision_tollerance) }
                               .first

    return unless left_side_collisions # return unless collision occurred

    # player's x is set to the value of the x of the collided rect's right side
    state.x = left_side_collisions[:left_right].right
    state.dx = 0 # player isn't moving left because its path is blocked
  end

  # Finds collisions between the right side of the player and the left side of a world_collision_rect.
  def collision_right!
    return unless state.dx > 0 # return unless player is moving right
    player_rect = [state.x + 0.1, state.y, state.tile_size, state.tile_size]

    # Goes through world_collision_rects to find all intersections between the player's right side
    # and the left side of a world_collision_rect (hence the "+0.1" above)
    right_side_collisions = state.world_collision_rects
                                .find_all { |r| r[:left_right].intersect_rect?(player_rect, collision_tollerance) }
                                .first

    return unless right_side_collisions # return unless collision occurred

    # player's x is set to the value of the collided rect's left, minus the size of a rect
    # tile size is subtracted because player's position is denoted by bottom left corner
    state.x = right_side_collisions[:left_right].left - state.tile_size
    state.dx = 0 # player isn't moving right because its path is blocked
  end

  # Finds collisions between the top of the player's rect and the bottom of a world_collision_rect.
  def collision_ceiling!
    return unless state.dy > 0 # return unless player is moving up
    player_rect = [state.x, state.y + 0.1, state.tile_size, state.tile_size]

    # Goes through world_collision_rects to find intersections between the bottom of a
    # world_collision_rect and the top of the player's rect (hence the "+0.1" above)
    ceil_collisions = state.world_collision_rects
                          .find_all { |r| r[:bottom].intersect_rect?(player_rect, collision_tollerance) }
                          .first

    return unless ceil_collisions # return unless collision occurred

    # player's y is set to the bottom y of the rect it collided with, minus the size of a rect
    state.y = ceil_collisions[:bottom].y - state.tile_size
    state.dy = 0 # if a collision occurred, the player isn't moving up because its path is blocked
  end

  # Makes sure the player remains within the screen's dimensions.
  def calc_edge_collision

    #Ensures that the player doesn't fall below the map.
    if state.y < 0
      state.y = 0
      state.dy = 0

    #Ensures that the player doesn't go too high.
    # Position of player is denoted by bottom left hand corner, which is why we have to subtract the
    # size of the player's box (so it remains visible on the screen)
    elsif state.y > 720 - state.tile_size # if the player's y position exceeds the height of screen
      state.y = 720 - state.tile_size # the player will remain as high as possible while staying on screen
      state.dy = 0
    end

    # Ensures that the player remains in the horizontal range that it is supposed to.
    if state.x >= 1280 - state.tile_size && state.dx > 0 # if player moves too far right
      state.x = 1280 - state.tile_size # player will remain as right as possible while staying on screen
      state.dx = 0
    elsif state.x <= 0 && state.dx < 0 # if player moves too far left
      state.x = 0 # player will remain as left as possible while remaining on screen
      state.dx = 0
    end
  end

  # Processes input from the user on the keyboard.
  def process_inputs
    if inputs.mouse.down
      state.world_lookup = {}
      x, y = to_coord inputs.mouse.down.point  # gets x, y coordinates for the grid

      if state.world.any? { |loc| loc == [x, y] }  # checks if coordinates duplicate
        state.world = state.world.reject { |loc| loc == [x, y] }  # erases tile space
      else
        state.world << [x, y] # If no duplicates, adds to world collection
      end
    end

    # Sets dx to 0 if the player lets go of arrow keys.
    if inputs.keyboard.key_up.right
      state.dx = 0
    elsif inputs.keyboard.key_up.left
      state.dx = 0
    end

    # Sets dx to 3 in whatever direction the player chooses.
    if inputs.keyboard.key_held.right # if right key is pressed
      state.dx =  3
    elsif inputs.keyboard.key_held.left # if left key is pressed
      state.dx = -3
    end

    #Sets dy to 5 to make the player ~fly~ when they press the space bar
    if inputs.keyboard.key_held.space
      state.dy = 5
    end
  end

  def to_coord point

    # Integer divides (idiv) point.x to turn into grid
    # Then, you can just multiply each integer by state.tile_size later so the grid coordinates.
    [point.x.idiv(state.tile_size), point.y.idiv(state.tile_size)]
  end

  # Represents the tolerance for a collision between the player's rect and another rect.
  def collision_tollerance
    0.0
  end
end

$platformer_physics = PoorManPlatformerPhysics.new

def tick args
  $platformer_physics.grid    = args.grid
  $platformer_physics.inputs  = args.inputs
  $platformer_physics.state    = args.state
  $platformer_physics.outputs = args.outputs
  $platformer_physics.tick
  tick_instructions args, "Sample app shows platformer collisions. CLICK to place box. ARROW keys to move around. SPACE to jump."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Box Collision 2 - main.rb link

    # ./samples/04_physics_and_collisions/05_box_collision_2/app/main.rb
=begin
 APIs listing that haven't been encountered in previous sample apps:

 - times: Performs an action a specific number of times.
   For example, if we said
   5.times puts "Hello DragonRuby",
   then we'd see the words "Hello DragonRuby" printed on the console 5 times.

 - split: Divides a string into substrings based on a delimiter.
   For example, if we had a command
   "DragonRuby is awesome".split(" ")
   then the result would be
   ["DragonRuby", "is", "awesome"] because the words are separated by a space delimiter.

 - join: Opposite of split; converts each element of array to a string separated by delimiter.
   For example, if we had a command
   ["DragonRuby","is","awesome"].join(" ")
   then the result would be
   "DragonRuby is awesome".

 Reminders:

 - to_s: Returns a string representation of an object.
   For example, if we had
   500.to_s
   the string "500" would be returned.
   Similar to to_i, which returns an integer representation of an object.

 - elapsed_time: How many frames have passed since the click event.

 - args.outputs.labels: An array. Values in the array generate labels on the screen.
   The parameters are: [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - inputs.mouse.down: Determines whether or not the mouse is being pressed down.
   The position of the mouse when it is pressed down can be found using inputs.mouse.down.point.(x|y).

 - first: Returns the first element of the array.

 - num1.idiv(num2): Divides two numbers and returns an integer.

 - find_all: Finds all values that satisfy specific requirements.

 - ARRAY#intersect_rect?: Returns true or false depending on if two rectangles intersect.

 - reject: Removes elements from a collection if they meet certain requirements.

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

=end

MAP_FILE_PATH = 'app/map.txt' # the map.txt file in the app folder contains exported map

class MetroidvaniaStarter
  attr_accessor :grid, :inputs, :state, :outputs, :gtk

  # Calls methods needed to run the game properly.
  def tick
    defaults
    render
    calc
    process_inputs
  end

  # Sets all the default variables.
  # '||' states that initialization occurs only in the first frame.
  def defaults
    state.tile_size                = 64
    state.gravity                  = -0.2
    state.player_width             = 60
    state.player_height            = 64
    state.collision_tolerance      = 0.0
    state.previous_tile_size     ||= state.tile_size
    state.x                      ||= 0
    state.y                      ||= 800
    state.dy                     ||= 0
    state.dx                     ||= 0
    attempt_load_world_from_file
    state.world_lookup           ||= { }
    state.world_collision_rects  ||= []
    state.mode                   ||= :creating # alternates between :creating and :selecting for sprite selection
    state.select_menu            ||= [0, 720, 1280, 720]
    #=======================================IMPORTANT=======================================#
    # When adding sprites, please label them "image1.png", "image2.png", image3".png", etc.
    # Once you have done that, adjust "state.sprite_quantity" to how many sprites you have.
    #=======================================================================================#
    state.sprite_quantity        ||= 20 # IMPORTANT TO ALTER IF SPRITES ADDED IF YOU ADD MORE SPRITES
    state.sprite_coords          ||= []
    state.banner_coords          ||= [640, 680 + 720]
    state.sprite_selected        ||= 1
    state.map_saved_at           ||= 0

    # Sets all the cordinate values for the sprite selection screen into a grid
    # Displayed when 's' is pressed by player to access sprites
    if state.sprite_coords == [] # if sprite_coords is an empty array
      count = 1
      temp_x = 165 # sets a starting x and y position for display
      temp_y = 500 + 720
      state.sprite_quantity.times do # for the number of sprites you have
        state.sprite_coords += [[temp_x, temp_y, count]] # add element to sprite_coords array
        temp_x += 100 # increment temp_x
        count += 1 # increment count
        if temp_x > 1280 - (165 + 50) # if exceeding specific horizontal width on screen
          temp_x = 165 # a new row of sprites starts
          temp_y -= 75 # new row of sprites starts 75 units lower than the previous row
        end
      end
    end
  end

  # Places sprites
  def render

    # Sets the x, y, width, height, and image path for each sprite in the world collection.
    outputs.sprites << state.world.map do |x, y, sprite|
      [x * state.tile_size, # multiply by size so grid coordinates; pixel value of location
       y * state.tile_size,
       state.tile_size,
       state.tile_size,
       'sprites/image' + sprite.to_s + '.png'] # uses concatenation to create unique image path
    end

    # Outputs sprite for the player by setting x, y, width, height, and image path
    outputs.sprites << [state.x,
                        state.y,
                        state.player_width,
                        state.player_height,'sprites/player.png']

    # Outputs labels as primitives in top right of the screen
    outputs.primitives << [920, 700, 'Press \'s\' to access sprites.', 1, 0].label
    outputs.primitives << [920, 675, 'Click existing sprite to delete.', 1, 0].label

    outputs.primitives << [920, 640, '<- and -> to move.', 1, 0].label
    outputs.primitives << [920, 615, 'Press and hold space to jump.', 1, 0].label

    outputs.primitives << [920, 580, 'Press \'e\' to export current map.', 1, 0].label

    # if the map is saved and less than 120 frames have passed, the label is displayed
    if state.map_saved_at > 0 && state.map_saved_at.elapsed_time < 120
      outputs.primitives << [920, 555, 'Map has been exported!', 1, 0, 50, 100, 50].label
    end

    # If player hits 's', following appears
    if state.mode == :selecting
      # White background for sprite selection
      outputs.primitives << [state.select_menu, 255, 255, 255].solid

      # Select tile label at the top of the screen
      outputs.primitives << [state.banner_coords.x, state.banner_coords.y, "Select Sprite (sprites located in \"sprites\" folder)", 10, 1, 0, 0, 0, 255].label

      # Places sprites in locations calculated in the defaults function
      outputs.primitives << state.sprite_coords.map do |x, y, order|
        [x, y, 50, 50, 'sprites/image' + order.to_s + ".png"].sprite
      end
    end

    # Creates sprite following mouse to help indicate which sprite you have selected
    # 10 is subtracted from the mouse's x position so that the sprite is not covered by the mouse icon
    outputs.primitives << [inputs.mouse.position.x - 10, inputs.mouse.position.y,
                           10, 10, 'sprites/image' + state.sprite_selected.to_s + ".png"].sprite
  end

  # Calls methods that perform calculations
  def calc
    calc_in_game
    calc_sprite_selection
  end

  # Calls methods that perform calculations (if in creating mode)
  def calc_in_game
    return unless state.mode == :creating
    calc_world_lookup
    calc_player
  end

  def calc_world_lookup
    # If the tile size isn't equal to the previous tile size,
    # the previous tile size is set to the tile size,
    # and world_lookup hash is set to empty.
    if state.tile_size != state.previous_tile_size
      state.previous_tile_size = state.tile_size
      state.world_lookup = {}
    end

    # return if world_lookup is not empty or if world is empty
    return if state.world_lookup.keys.length > 0
    return unless state.world.length > 0

    # Searches through the world and finds the coordinates that exist
    state.world_lookup = {}
    state.world.each { |x, y| state.world_lookup[[x, y]] = true }

    # Assigns collision rects for every sprite drawn
    state.world_collision_rects =
      state.world_lookup
           .keys
           .map do |coord_x, coord_y|
             s = state.tile_size
             # Multiplying by s (the size of a tile) ensures that the rect is
             # placed exactly where you want it to be placed (causes grid to coordinate)
             # How many pixels horizontally across and vertically up and down
             x = s * coord_x
             y = s * coord_y
             {
               args:       [coord_x, coord_y],
               left_right: [x,     y + 4, s,     s - 6], # hash keys and values
               top:        [x + 4, y + 6, s - 8, s - 6],
               bottom:     [x + 1, y - 1, s - 2, s - 8],
             }
           end
  end

  # Calculates movement of player and calls methods that perform collision calculations
  def calc_player
    state.dy += state.gravity  # what goes up must come down because of gravity
    calc_box_collision
    calc_edge_collision
    state.y  += state.dy       # Since velocity is the change in position, the change in y increases by dy
    state.x  += state.dx       # Ditto line above but dx and x
    state.dx *= 0.8            # Scales dx down
  end

  # Calls methods that determine whether the player collides with any world_collision_rects.
  def calc_box_collision
    return unless state.world_lookup.keys.length > 0 # return unless hash has atleast 1 key
    collision_floor
    collision_left
    collision_right
    collision_ceiling
  end

  # Finds collisions between the bottom of the player's rect and the top of a world_collision_rect.
  def collision_floor
    return unless state.dy <= 0 # return unless player is going down or is as far down as possible
    player_rect = [state.x, next_y, state.tile_size, state.tile_size] # definition of player

    # Runs through all the sprites on the field and finds all intersections between player's
    # bottom and the top of a rect.
    floor_collisions = state.world_collision_rects
                         .find_all { |r| r[:top].intersect_rect?(player_rect, state.collision_tolerance) }
                         .first

    return unless floor_collisions # performs following changes if a collision has occurred
    state.y = floor_collisions[:top].top # y of player is set to the y of the colliding rect's top
    state.dy = 0 # no change in y because the player's path is blocked
  end

  # Finds collisions between the player's left side and the right side of a world_collision_rect.
  def collision_left
    return unless state.dx < 0 # return unless player is moving left
    player_rect = [next_x, state.y, state.tile_size, state.tile_size]

    # Runs through all the sprites on the field and finds all intersections between the player's left side
    # and the right side of a rect.
    left_side_collisions = state.world_collision_rects
                             .find_all { |r| r[:left_right].intersect_rect?(player_rect, state.collision_tolerance) }
                             .first

    return unless left_side_collisions # return unless collision occurred
    state.x = left_side_collisions[:left_right].right # sets player's x to the x of the colliding rect's right side
    state.dx = 0 # no change in x because the player's path is blocked
  end

  # Finds collisions between the right side of the player and the left side of a world_collision_rect.
  def collision_right
    return unless state.dx > 0 # return unless player is moving right
    player_rect = [next_x, state.y, state.tile_size, state.tile_size]

    # Runs through all the sprites on the field and finds all intersections between the  player's
    # right side and the left side of a rect.
    right_side_collisions = state.world_collision_rects
                              .find_all { |r| r[:left_right].intersect_rect?(player_rect, state.collision_tolerance) }
                              .first

    return unless right_side_collisions # return unless collision occurred
    state.x = right_side_collisions[:left_right].left - state.tile_size # player's x is set to the x of colliding rect's left side (minus tile size since x is the player's bottom left corner)
    state.dx = 0 # no change in x because the player's path is blocked
  end

  # Finds collisions between the top of the player's rect and the bottom of a world_collision_rect.
  def collision_ceiling
    return unless state.dy > 0 # return unless player is moving up
    player_rect = [state.x, next_y, state.player_width, state.player_height]

    # Runs through all the sprites on the field and finds all intersections between the player's top
    # and the bottom of a rect.
    ceil_collisions = state.world_collision_rects
                        .find_all { |r| r[:bottom].intersect_rect?(player_rect, state.collision_tolerance) }
                        .first

    return unless ceil_collisions # return unless collision occurred
    state.y = ceil_collisions[:bottom].y - state.tile_size # player's y is set to the y of the colliding rect's bottom (minus tile size)
    state.dy = 0 # no change in y because the player's path is blocked
  end

  # Makes sure the player remains within the screen's dimensions.
  def calc_edge_collision
    # Ensures that player doesn't fall below the map
    if next_y < 0 && state.dy < 0 # if player is moving down and is about to fall (next_y) below the map's scope
      state.y = 0 # 0 is the lowest the player can be while staying on the screen
      state.dy = 0
    # Ensures player doesn't go insanely high
    elsif next_y > 720 - state.tile_size && state.dy > 0 # if player is moving up, about to exceed map's scope
      state.y = 720 - state.tile_size # if we don't subtract tile_size, we won't be able to see the player on the screen
      state.dy = 0
    end

    # Ensures that player remains in the horizontal range its supposed to
    if state.x >= 1280 - state.tile_size && state.dx > 0 # if the player is moving too far right
      state.x = 1280 - state.tile_size # farthest right the player can be while remaining in the screen's scope
      state.dx = 0
    elsif state.x <= 0 && state.dx < 0 # if the player is moving too far left
      state.x = 0 # farthest left the player can be while remaining in the screen's scope
      state.dx = 0
    end
  end

  def calc_sprite_selection
    # Does the transition to bring down the select sprite screen
    if state.mode == :selecting && state.select_menu.y != 0
      state.select_menu.y = 0  # sets y position of select menu (shown when 's' is pressed)
      state.banner_coords.y = 680 # sets y position of Select Sprite banner
      state.sprite_coords = state.sprite_coords.map do |x, y, w, h|
        [x, y - 720, w, h] # sets definition of sprites (change '-' to '+' and the sprites can't be seen)
      end
    end

    # Does the transition to leave the select sprite screen
    if state.mode == :creating  && state.select_menu.y != 720
      state.select_menu.y = 720 # sets y position of select menu (menu is retreated back up)
      state.banner_coords.y = 1000 # sets y position of Select Sprite banner
      state.sprite_coords = state.sprite_coords.map do |x, y, w, h|
        [x, y + 720, w, h] # sets definition of all elements in collection
      end
    end
  end

  def process_inputs
    # If the state.mode is back and if the menu has retreated back up
    # call methods that process user inputs
    if state.mode == :creating
      process_inputs_player_movement
      process_inputs_place_tile
    end

    # For each sprite_coordinate added, check what sprite was selected
    if state.mode == :selecting
      state.sprite_coords.map do |x, y, order| # goes through all sprites in collection
        # checks that a specific sprite was pressed based on x, y position
        if inputs.mouse.down && # the && (and) sign means ALL statements must be true for the evaluation to be true
           inputs.mouse.down.point.x >= x      && # x is greater than or equal to sprite's x and
           inputs.mouse.down.point.x <= x + 50 && # x is less than or equal to 50 pixels to the right
           inputs.mouse.down.point.y >= y      && # y is greater than or equal to sprite's y
           inputs.mouse.down.point.y <= y + 50 # y is less than or equal to 50 pixels up
          state.sprite_selected = order # sprite is chosen
        end
      end
    end

    inputs_export_stage
    process_inputs_show_available_sprites
  end

  # Moves the player based on the keys they press on their keyboard
  def process_inputs_player_movement
    # Sets dx to 0 if the player lets go of arrow keys (player won't move left or right)
    if inputs.keyboard.key_up.right
      state.dx = 0
    elsif inputs.keyboard.key_up.left
      state.dx = 0
    end

    # Sets dx to 3 in whatever direction the player chooses when they hold down (or press) the left or right keys
    if inputs.keyboard.key_held.right
      state.dx =  3
    elsif inputs.keyboard.key_held.left
      state.dx = -3
    end

    # Sets dy to 5 to make the player ~fly~ when they press the space bar on their keyboard
    if inputs.keyboard.key_held.space
      state.dy = 5
    end
  end

  # Adds tile in the place the user holds down the mouse
  def process_inputs_place_tile
    if inputs.mouse.down # if mouse is pressed
      state.world_lookup = {}
      x, y = to_coord inputs.mouse.down.point # gets x, y coordinates for the grid

      # Checks if any coordinates duplicate (already exist in world)
      if state.world.any? { |existing_x, existing_y, n| existing_x == x && existing_y == y }
        #erases existing tile space by rejecting them from world
        state.world = state.world.reject do |existing_x, existing_y, n|
          existing_x == x && existing_y == y
        end
      else
        state.world << [x, y, state.sprite_selected] # If no duplicates, add the sprite
      end
    end
  end

  # Stores/exports world collection's info (coordinates, sprite number) into a file
  def inputs_export_stage
    if inputs.keyboard.key_down.e # if "e" is pressed
      export_string = state.world.map do |x, y, sprite_number| # stores world info in a string
        "#{x},#{y},#{sprite_number}"                           # using string interpolation
      end
      gtk.write_file(MAP_FILE_PATH, export_string.join("\n")) # writes string into a file
      state.map_saved_at = state.tick_count # frame number (passage of time) when the map was saved
    end
  end

  def process_inputs_show_available_sprites
    # Based on keyboard input, the entity (:creating and :selecting) switch
    if inputs.keyboard.key_held.s && state.mode == :creating # if "s" is pressed and currently creating
      state.mode = :selecting # will change to selecting
      inputs.keyboard.clear # VERY IMPORTANT! If not present, it'll flicker between on and off
    elsif inputs.keyboard.key_held.s && state.mode == :selecting # if "s" is pressed and currently selecting
      state.mode = :creating # will change to creating
      inputs.keyboard.clear # VERY IMPORTANT! If not present, it'll flicker between on and off
    end
  end

  # Loads the world collection by reading from the map.txt file in the app folder
  def attempt_load_world_from_file
    return if state.world # return if the world collection is already populated
    state.world ||= [] # initialized as an empty collection
    exported_world = gtk.read_file(MAP_FILE_PATH) # reads the file using the path mentioned at top of code
    return unless exported_world # return unless the file read was successful
    state.world = exported_world.each_line.map do |l| # perform action on each line of exported_world
        l.split(',').map(&:to_i) # calls split using ',' as a delimiter, and invokes .map on the collection,
                                 # calling to_i (converts to integers) on each element
    end
  end

  # Adds the change in y to y to determine the next y position of the player.
  def next_y
    state.y + state.dy
  end

  # Determines next x position of player
  def next_x
    if state.dx < 0 # if the player moves left
      return state.x - (state.tile_size - state.player_width) # subtracts since the change in x is negative (player is moving left)
    else
      return state.x + (state.tile_size - state.player_width) # adds since the change in x is positive (player is moving right)
    end
  end

  def to_coord point
    # Integer divides (idiv) point.x to turn into grid
    # Then, you can just multiply each integer by state.tile_size
    # later and huzzah. Grid coordinates
    [point.x.idiv(state.tile_size), point.y.idiv(state.tile_size)]
  end
end

$metroidvania_starter = MetroidvaniaStarter.new

def tick args
    $metroidvania_starter.grid    = args.grid
    $metroidvania_starter.inputs  = args.inputs
    $metroidvania_starter.state   = args.state
    $metroidvania_starter.outputs = args.outputs
    $metroidvania_starter.gtk     = args.gtk
    $metroidvania_starter.tick
end

    Box Collision 3 - main.rb link

    # ./samples/04_physics_and_collisions/06_box_collision_3/app/main.rb
class Game
  attr_gtk

  def tick
    defaults
    render
    input_edit_map
    input_player
    calc_player
  end

  def defaults
    state.gravity           = -0.4
    state.drag              = 0.15
    state.tile_size         = 32
    state.player.size       = 16
    state.player.jump_power = 12

    state.tiles                 ||= []
    state.player.y              ||= 800
    state.player.x              ||= 100
    state.player.dy             ||= 0
    state.player.dx             ||= 0
    state.player.jumped_down_at ||= 0
    state.player.jumped_at      ||= 0

    calc_player_rect if !state.player.rect
  end

  def render
    outputs.labels << [10, 10.from_top, "tile: click to add a tile, hold X key and click to delete a tile."]
    outputs.labels << [10, 35.from_top, "move: use left and right to move, space to jump, down and space to jump down."]
    outputs.labels << [10, 55.from_top, "      You can jump through or jump down through tiles with a height of 1."]
    outputs.background_color = [80, 80, 80]
    outputs.sprites << tiles.map(&:sprite)
    outputs.sprites << (player.rect.merge path: 'sprites/square/green.png')

    mouse_overlay = {
      x: (inputs.mouse.x.ifloor state.tile_size),
      y: (inputs.mouse.y.ifloor state.tile_size),
      w: state.tile_size,
      h: state.tile_size,
      a: 100
    }

    mouse_overlay = mouse_overlay.merge r: 255 if state.delete_mode

    if state.mouse_held
      outputs.primitives << mouse_overlay.border!
    else
      outputs.primitives << mouse_overlay.solid!
    end
  end

  def input_edit_map
    state.mouse_held = true  if inputs.mouse.down
    state.mouse_held = false if inputs.mouse.up

    if inputs.keyboard.x
      state.delete_mode = true
    elsif inputs.keyboard.key_up.x
      state.delete_mode = false
    end

    return unless state.mouse_held

    ordinal = { x: (inputs.mouse.x.idiv state.tile_size),
                y: (inputs.mouse.y.idiv state.tile_size) }

    found = find_tile ordinal
    if !found && !state.delete_mode
      tiles << (state.new_entity :tile, ordinal)
      recompute_tiles
    elsif found && state.delete_mode
      tiles.delete found
      recompute_tiles
    end
  end

  def input_player
    player.dx += inputs.left_right

    if inputs.keyboard.key_down.space && inputs.keyboard.down
      player.dy             = player.jump_power * -1
      player.jumped_at      = 0
      player.jumped_down_at = state.tick_count
    elsif inputs.keyboard.key_down.space
      player.dy             = player.jump_power
      player.jumped_at      = state.tick_count
      player.jumped_down_at = 0
    end
  end

  def calc_player
    calc_player_rect
    calc_below
    calc_left
    calc_right
    calc_above
    calc_player_dy
    calc_player_dx
    reset_player if player_off_stage?
  end

  def calc_player_rect
    player.rect      = current_player_rect
    player.next_rect = player.rect.merge x: player.x + player.dx,
                                         y: player.y + player.dy
    player.prev_rect = player.rect.merge x: player.x - player.dx,
                                         y: player.y - player.dy
  end

  def calc_below
    return unless player.dy <= 0
    tiles_below = find_tiles { |t| t.rect.top <= player.prev_rect.y }
    collision = find_colliding_tile tiles_below, (player.rect.merge y: player.next_rect.y)
    return unless collision
    if collision.neighbors.b == :none && player.jumped_down_at.elapsed_time < 10
      player.dy = -1
    else
      player.y  = collision.rect.y + state.tile_size
      player.dy = 0
    end
  end

  def calc_left
    return unless player.dx < 0
    tiles_left = find_tiles { |t| t.rect.right <= player.prev_rect.left }
    collision = find_colliding_tile tiles_left, (player.rect.merge x: player.next_rect.x)
    return unless collision
    player.x  = collision.rect.right
    player.dx = 0
  end

  def calc_right
    return unless player.dx > 0
    tiles_right = find_tiles { |t| t.rect.left >= player.prev_rect.right }
    collision = find_colliding_tile tiles_right, (player.rect.merge x: player.next_rect.x)
    return unless collision
    player.x  = collision.rect.left - player.rect.w
    player.dx = 0
  end

  def calc_above
    return unless player.dy > 0
    tiles_above = find_tiles { |t| t.rect.y >= player.prev_rect.y }
    collision = find_colliding_tile tiles_above, (player.rect.merge y: player.next_rect.y)
    return unless collision
    return if collision.neighbors.t == :none
    player.dy = 0
    player.y  = collision.rect.bottom - player.rect.h
  end

  def calc_player_dx
    player.dx  = player.dx.clamp(-5,  5)
    player.dx *= 0.9
    player.x  += player.dx
  end

  def calc_player_dy
    player.y  += player.dy
    player.dy += state.gravity
    player.dy += player.dy * state.drag ** 2 * -1
  end

  def reset_player
    player.x  = 100
    player.y  = 720
    player.dy = 0
  end

  def recompute_tiles
    tiles.each do |t|
      t.w = state.tile_size
      t.h = state.tile_size
      t.neighbors = tile_neighbors t, tiles

      t.rect = [t.x * state.tile_size,
                t.y * state.tile_size,
                state.tile_size,
                state.tile_size].rect.to_hash

      sprite_sub_path = t.neighbors.mask.map { |m| flip_bit m }.join("")

      t.sprite = {
        x: t.x * state.tile_size,
        y: t.y * state.tile_size,
        w: state.tile_size,
        h: state.tile_size,
        path: "sprites/tile/wall-#{sprite_sub_path}.png"
      }
    end
  end

  def flip_bit bit
    return 0 if bit == 1
    return 1
  end

  def player
    state.player
  end

  def player_off_stage?
    player.rect.top < grid.bottom ||
    player.rect.right < grid.left ||
    player.rect.left > grid.right
  end

  def current_player_rect
    { x: player.x, y: player.y, w: player.size, h: player.size }
  end

  def tiles
    state.tiles
  end

  def find_tile ordinal
    tiles.find { |t| t.x == ordinal.x && t.y == ordinal.y }
  end

  def find_tiles &block
    tiles.find_all(&block)
  end

  def find_colliding_tile tiles, target
    tiles.find { |t| t.rect.intersect_rect? target }
  end

  def tile_neighbors tile, other_points
    t = find_tile x: tile.x + 0, y: tile.y + 1
    r = find_tile x: tile.x + 1, y: tile.y + 0
    b = find_tile x: tile.x + 0, y: tile.y - 1
    l = find_tile x: tile.x - 1, y: tile.y + 0

    tile_t, tile_r, tile_b, tile_l = 0

    tile_t = 1 if t
    tile_r = 1 if r
    tile_b = 1 if b
    tile_l = 1 if l

    state.new_entity :neighbors, mask: [tile_t, tile_r, tile_b, tile_l],
                                 t:    t ? :some : :none,
                                 b:    b ? :some : :none,
                                 l:    l ? :some : :none,
                                 r:    r ? :some : :none
  end
end

def tick args
  $game ||= Game.new
  $game.args = args
  $game.tick
end

    Jump Physics - main.rb link

    # ./samples/04_physics_and_collisions/07_jump_physics/app/main.rb
=begin

 Reminders:

 - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
   For example, if we want to create a new button, we would declare it as a new entity and
   then define its properties. (Remember, you can use state to define ANY property and it will
   be retained across frames.)

 - args.outputs.solids: An array. The values generate a solid.
   The parameters for a solid are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.

 - num1.greater(num2): Returns the greater value.

 - Hashes: Collection of unique keys and their corresponding values. The value can be found
   using their keys.

 - ARRAY#inside_rect?: Returns true or false depending on if the point is inside the rect.

=end

# This sample app is a game that requires the user to jump from one platform to the next.
# As the player successfully clears platforms, they become smaller and move faster.

class VerticalPlatformer
  attr_gtk

  # declares vertical platformer as new entity
  def s
    state.vertical_platformer ||= state.new_entity(:vertical_platformer)
    state.vertical_platformer
  end

  # creates a new platform using a hash
  def new_platform hash
    s.new_entity_strict(:platform, hash) # platform key
  end

  # calls methods needed for game to run properly
  def tick
    defaults
    render
    calc
    input
  end

  def init_game
    s.platforms ||= [ # initializes platforms collection with two platforms using hashes
      new_platform(x: 0, y: 0, w: 700, h: 32, dx: 1, speed: 0, rect: nil),
      new_platform(x: 0, y: 300, w: 700, h: 32, dx: 1, speed: 0, rect: nil), # 300 pixels higher
    ]

    s.tick_count  = args.state.tick_count
    s.gravity     = -0.3 # what goes up must come down because of gravity
    s.player.platforms_cleared ||= 0 # counts how many platforms the player has successfully cleared
    s.player.x  ||= 0           # sets player values
    s.player.y  ||= 100
    s.player.w  ||= 64
    s.player.h  ||= 64
    s.player.dy ||= 0           # change in position
    s.player.dx ||= 0
    s.player_jump_power           = 15
    s.player_jump_power_duration  = 10
    s.player_max_run_speed        = 5
    s.player_speed_slowdown_rate  = 0.9
    s.player_acceleration         = 1
    s.camera ||= { y: -100 } # shows view on screen (as the player moves upward, the camera does too)
  end

  # Sets default values
  def defaults
    init_game
  end

  # Outputs objects onto the screen
  def render
    outputs.solids << s.platforms.map do |p| # outputs platforms onto screen
      [p.x + 300, p.y - s.camera[:y], p.w, p.h] # add 300 to place platform in horizontal center
      # don't forget, position of platform is denoted by bottom left hand corner
    end

    # outputs player using hash
    outputs.solids << {
      x: s.player.x + 300, # player positioned on top of platform
      y: s.player.y - s.camera[:y],
      w: s.player.w,
      h: s.player.h,
      r: 100,              # color saturation
      g: 100,
      b: 200
    }
  end

  # Performs calculations
  def calc
    s.platforms.each do |p| # for each platform in the collection
      p.rect = [p.x, p.y, p.w, p.h] # set the definition
    end

    # sets player point by adding half the player's width to the player's x
    s.player.point = [s.player.x + s.player.w.half, s.player.y] # change + to - and see what happens!

    # search the platforms collection to find if the player's point is inside the rect of a platform
    collision = s.platforms.find { |p| s.player.point.inside_rect? p.rect }

    # if collision occurred and player is moving down (or not moving vertically at all)
    if collision && s.player.dy <= 0
      s.player.y = collision.rect.y + collision.rect.h - 2 # player positioned on top of platform
      s.player.dy = 0 if s.player.dy < 0 # player stops moving vertically
      if !s.player.platform
        s.player.dx = 0 # no horizontal movement
      end
      # changes horizontal position of player by multiplying collision change in x (dx) by speed and adding it to current x
      s.player.x += collision.dx * collision.speed
      s.player.platform = collision # player is on the platform that it collided with (or landed on)
      if s.player.falling # if player is falling
        s.player.dx = 0  # no horizontal movement
      end
      s.player.falling = false
      s.player.jumped_at = nil
    else
      s.player.platform = nil # player is not on a platform
      s.player.y  += s.player.dy # velocity is the change in position
      s.player.dy += s.gravity # acceleration is the change in velocity; what goes up must come down
    end

    s.platforms.each do |p| # for each platform in the collection
      p.x += p.dx * p.speed # x is incremented by product of dx and speed (causes platform to move horizontally)
      # changes platform's x so it moves left and right across the screen (between -300 and 300 pixels)
      if p.x < -300 # if platform goes too far left
        p.dx *= -1 # dx is scaled down
        p.x = -300 # as far left as possible within scope
      elsif p.x > (1000 - p.w) # if platform's x is greater than 300
        p.dx *= -1
        p.x = (1000 - p.w) # set to 300 (as far right as possible within scope)
      end
    end

    delta = (s.player.y - s.camera[:y] - 100) # used to position camera view

    if delta > -200
      s.camera[:y] += delta * 0.01 # allows player to see view as they move upwards
      s.player.x  += s.player.dx # velocity is change in position; change in x increases by dx

      # searches platform collection to find platforms located more than 300 pixels above the player
      has_platforms = s.platforms.find { |p| p.y > (s.player.y + 300) }
      if !has_platforms # if there are no platforms 300 pixels above the player
        width = 700 - (700 * (0.1 * s.player.platforms_cleared)) # the next platform is smaller than previous
        s.player.platforms_cleared += 1 # player successfully cleared another platform
        last_platform = s.platforms[-1] # platform just cleared becomes last platform
        # another platform is created 300 pixels above the last platform, and this
        # new platform has a smaller width and moves faster than all previous platforms
        s.platforms << new_platform(x: (700 - width) * rand, # random x position
                                    y: last_platform.y + 300,
                                    w: width,
                                    h: 32,
                                    dx: 1.randomize(:sign), # random change in x
                                    speed: 2 * s.player.platforms_cleared,
                                    rect: nil)
      end
    else
      # game over
      s.as_hash.clear # otherwise clear the hash (no new platform is necessary)
      init_game
    end
  end

  # Takes input from the user to move the player
  def input
    if inputs.keyboard.space # if the space bar is pressed
      s.player.jumped_at ||= s.tick_count # set to current frame

      # if the time that has passed since the jump is less than the duration of a jump (10 frames)
      # and the player is not falling
      if s.player.jumped_at.elapsed_time < s.player_jump_power_duration && !s.player.falling
        s.player.dy = s.player_jump_power # player jumps up
      end
    end

    if inputs.keyboard.key_up.space # if space bar is in "up" state
      s.player.falling = true # player is falling
    end

    if inputs.keyboard.left # if left key is pressed
      s.player.dx -= s.player_acceleration # player's position changes, decremented by acceleration
      s.player.dx = s.player.dx.greater(-s.player_max_run_speed) # dx is either current dx or -5, whichever is greater
    elsif inputs.keyboard.right # if right key is pressed
      s.player.dx += s.player_acceleration # player's position changes, incremented by acceleration
      s.player.dx  = s.player.dx.lesser(s.player_max_run_speed) # dx is either current dx or 5, whichever is lesser
    else
      s.player.dx *= s.player_speed_slowdown_rate # scales dx down
    end
  end
end

$game = VerticalPlatformer.new

def tick args
  $game.args = args
  $game.tick
end

    Bouncing On Collision - ball.rb link

    # ./samples/04_physics_and_collisions/08_bouncing_on_collision/app/ball.rb
GRAVITY = -0.08

class Ball
    attr_accessor :velocity, :center, :radius, :collision_enabled

    def initialize args
        #Start the ball in the top center
        #@x = args.grid.w / 2
        #@y = args.grid.h - 20

        @velocity = {x: 0, y: 0}
        #@width =  20
        #@height = @width
        @radius = 20.0 / 2.0
        @center = {x: (args.grid.w / 2), y: (args.grid.h)}

        #@left_wall = (args.state.board_width + args.grid.w / 8)
        #@right_wall = @left_wall + args.state.board_width
        @left_wall = 0
        @right_wall = $args.grid.right

        @max_velocity = 7
        @collision_enabled = true
    end

    #Move the ball according to its velocity
    def update args
      @center.x += @velocity.x
      @center.y += @velocity.y
      @velocity.y += GRAVITY

      alpha = 0.2
      if @center.y-@radius <= 0
        @velocity.y  = (@velocity.y.abs*0.7).abs
        @velocity.x  = (@velocity.x.abs*0.9).abs * ((@velocity.x < 0) ? -1 : 1)

        if @velocity.y.abs() < alpha
          @velocity.y=0
        end
        if @velocity.x.abs() < alpha
          @velocity.x=0
        end
      end

      if @center.x > args.grid.right+@radius*2
        @center.x = 0-@radius
      elsif @center.x< 0-@radius*2
        @center.x = args.grid.right + @radius
      end
    end

    def wallBounds args
        #if @x < @left_wall || @x + @width > @right_wall
            #@velocity.x *= -1.1
            #if @velocity.x > @max_velocity
                #@velocity.x = @max_velocity
            #elsif @velocity.x < @max_velocity * -1
                #@velocity.x = @max_velocity * -1
            #end
        #end
        #if @y < 0 || @y + @height > args.grid.h
            #@velocity.y *= -1.1
            #if @velocity.y > @max_velocity
                #@velocity.y = @max_velocity
            #elsif @velocity.y < @max_velocity * -1
                #@velocity.y = @max_velocity * -1
            #end
        #end
    end

    #render the ball to the screen
    def draw args
        #args.outputs.solids << [@x, @y, @width, @height, 255, 255, 0];
        args.outputs.sprites << [
          @center.x-@radius,
          @center.y-@radius,
          @radius*2,
          @radius*2,
          "sprites/circle-white.png",
          0,
          255,
          255,    #r
          0,    #g
          255   #b
        ]
    end
  end

    Bouncing On Collision - block.rb link

    # ./samples/04_physics_and_collisions/08_bouncing_on_collision/app/block.rb
DEGREES_TO_RADIANS = Math::PI / 180

class Block
  def initialize(x, y, block_size, rotation)
    @x = x
    @y = y
    @block_size = block_size
    @rotation = rotation

    #The repel velocity?
    @velocity = {x: 2, y: 0}

    horizontal_offset = (3 * block_size) * Math.cos(rotation * DEGREES_TO_RADIANS)
    vertical_offset = block_size * Math.sin(rotation * DEGREES_TO_RADIANS)

    if rotation >= 0
      theta = 90 - rotation
      #The line doesn't visually line up exactly with the edge of the sprite, so artificially move it a bit
      modifier = 5
      x_offset = modifier * Math.cos(theta * DEGREES_TO_RADIANS)
      y_offset = modifier * Math.sin(theta * DEGREES_TO_RADIANS)
      @x1 = @x - x_offset
      @y1 = @y + y_offset
      @x2 = @x1 + horizontal_offset
      @y2 = @y1 + (vertical_offset * 3)

      @imaginary_line = [ @x1, @y1, @x2, @y2 ]
    else
      theta = 90 + rotation
      x_offset = @block_size * Math.cos(theta * DEGREES_TO_RADIANS)
      y_offset = @block_size * Math.sin(theta * DEGREES_TO_RADIANS)
      @x1 = @x + x_offset
      @y1 = @y + y_offset + 19
      @x2 = @x1 + horizontal_offset
      @y2 = @y1 + (vertical_offset * 3)

      @imaginary_line = [ @x1, @y1, @x2, @y2 ]
    end

  end

  def draw args
    args.outputs.sprites << [
      @x,
      @y,
      @block_size*3,
      @block_size,
      "sprites/square-green.png",
      @rotation
    ]

    args.outputs.lines << @imaginary_line
    args.outputs.solids << @debug_shape
  end

  def multiply_matricies
  end

  def calc args
    if collision? args
        collide args
    end
  end

  #Determine if the ball and block are touching
  def collision? args
    #The minimum area enclosed by the center of the ball and the 2 corners of the block
    #If the area ever drops below this value, we know there is a collision
    min_area = ((@block_size * 3) * args.state.ball.radius) / 2

    #https://www.mathopenref.com/coordtrianglearea.html
    ax = @x1
    ay = @y1
    bx = @x2
    by = @y2
    cx = args.state.ball.center.x
    cy = args.state.ball.center.y

    current_area = (ax*(by-cy)+bx*(cy-ay)+cx*(ay-by))/2

    collision = false
    if @rotation >= 0
      if (current_area < min_area &&
        current_area > 0 &&
        args.state.ball.center.y > @y1 &&
        args.state.ball.center.x < @x2)

        collision = true
      end
    else
      if (current_area < min_area &&
        current_area > 0 &&
        args.state.ball.center.y > @y2 &&
        args.state.ball.center.x > @x1)

      collision = true
      end
    end

    return collision
  end

  def collide args
    #Slope of the block
    slope = (@y2 - @y1) / (@x2 - @x1)

    #Create a unit vector and tilt it (@rotation) number of degrees
    x = -Math.cos(@rotation * DEGREES_TO_RADIANS)
    y = Math.sin(@rotation * DEGREES_TO_RADIANS)

    #Find the vector that is perpendicular to the slope
    perpVect = { x: x, y: y }
    mag  = (perpVect.x**2 + perpVect.y**2)**0.5                                 # find the magniude of the perpVect
    perpVect = {x: perpVect.x/(mag), y: perpVect.y/(mag)}                       # divide the perpVect by the magniude to make it a unit vector

    previousPosition = {                                                        # calculate an ESTIMATE of the previousPosition of the ball
      x:args.state.ball.center.x-args.state.ball.velocity.x,
      y:args.state.ball.center.y-args.state.ball.velocity.y
    }

    velocityMag = (args.state.ball.velocity.x**2 + args.state.ball.velocity.y**2)**0.5 # the current velocity magnitude of the ball
    theta_ball = Math.atan2(args.state.ball.velocity.y, args.state.ball.velocity.x)         #the angle of the ball's velocity
    theta_repel = (180 * DEGREES_TO_RADIANS) - theta_ball + (@rotation * DEGREES_TO_RADIANS)

    fbx = velocityMag * Math.cos(theta_ball)                                    #the x component of the ball's velocity
    fby = velocityMag * Math.sin(theta_ball)                                    #the y component of the ball's velocity

    frx = velocityMag * Math.cos(theta_repel)                                       #the x component of the repel's velocity | magnitude is set to twice of fbx
    fry = velocityMag * Math.sin(theta_repel)                                       #the y component of the repel's velocity | magnitude is set to twice of fby

    args.state.display_value = velocityMag
    fsumx = fbx+frx                                                             #sum of x forces
    fsumy = fby+fry                                                             #sum of y forces
    fr = velocityMag                                                            #fr is the resulting magnitude
    thetaNew = Math.atan2(fsumy, fsumx)                                         #thetaNew is the resulting angle

    xnew = fr*Math.cos(thetaNew)                                                #resulting x velocity
    ynew = fr*Math.sin(thetaNew)                                                #resulting y velocity

    dampener = 0.3
    ynew *= dampener * 0.5

    #If the bounce is very low, that means the ball is rolling and we don't want to dampenen the X velocity
    if ynew > -0.1
      xnew *= dampener
    end

    #Add the sine component of gravity back in (X component)
    gravity_x = 4 * Math.sin(@rotation * DEGREES_TO_RADIANS)
    xnew += gravity_x

    args.state.ball.velocity.x = -xnew
    args.state.ball.velocity.y = -ynew

    #Set the position of the ball to the previous position so it doesn't warp throught the block
    args.state.ball.center.x = previousPosition.x
    args.state.ball.center.y = previousPosition.y
  end
end

    Bouncing On Collision - cannon.rb link

    # ./samples/04_physics_and_collisions/08_bouncing_on_collision/app/cannon.rb
class Cannon
  def initialize args
    @pointA = {x: args.grid.right/2,y: args.grid.top}
    @pointB = {x: args.inputs.mouse.x, y: args.inputs.mouse.y}
  end
  def update args
    activeBall = args.state.ball
    @pointB = {x: args.inputs.mouse.x, y: args.inputs.mouse.y}

    if args.inputs.mouse.click
      alpha = 0.01
      activeBall.velocity.y = (@pointB.y - @pointA.y) * alpha
      activeBall.velocity.x = (@pointB.x - @pointA.x) * alpha
      activeBall.center = {x: (args.grid.w / 2), y: (args.grid.h)}
    end
  end
  def render args
    args.outputs.lines << [@pointA.x, @pointA.y, @pointB.x, @pointB.y]
  end
end

    Bouncing On Collision - main.rb link

    # ./samples/04_physics_and_collisions/08_bouncing_on_collision/app/main.rb
INFINITY= 10**10

require 'app/vector2d.rb'
require 'app/peg.rb'
require 'app/block.rb'
require 'app/ball.rb'
require 'app/cannon.rb'


#Method to init default values
def defaults args
  args.state.pegs ||= []
  args.state.blocks ||= []
  args.state.cannon ||= Cannon.new args
  args.state.ball ||= Ball.new args
  args.state.horizontal_offset ||= 0
  init_pegs args
  init_blocks args

  args.state.display_value ||= "test"
end

begin :default_methods
  def init_pegs args
    num_horizontal_pegs = 14
    num_rows = 5

    return unless args.state.pegs.count < num_rows * num_horizontal_pegs

    block_size = 32
    block_spacing = 50
    total_width = num_horizontal_pegs * (block_size + block_spacing)
    starting_offset = (args.grid.w - total_width) / 2 + block_size

    for i in (0...num_rows)
      for j in (0...num_horizontal_pegs)
        row_offset = 0
        if i % 2 == 0
          row_offset = 20
        else
          row_offset = -20
        end
        args.state.pegs.append(Peg.new(j * (block_size+block_spacing) + starting_offset + row_offset, (args.grid.h - block_size * 2) - (i * block_size * 2)-90, block_size))
      end
    end

  end

  def init_blocks args
    return unless args.state.blocks.count < 10

    #Sprites are rotated in degrees, but the Ruby math functions work on radians
    radians_to_degrees = Math::PI / 180

    block_size = 25
    #Rotation angle (in degrees) of the blocks
    rotation = 30
    vertical_offset = block_size * Math.sin(rotation * radians_to_degrees)
    horizontal_offset = (3 * block_size) * Math.cos(rotation * radians_to_degrees)
    center = args.grid.w / 2

    for i in (0...5)
      #Create a ramp of blocks. Not going to be perfect because of the float to integer conversion and anisotropic to isotropic coversion
      args.state.blocks.append(Block.new((center + 100 + (i * horizontal_offset)).to_i, 100 + (vertical_offset * i) + (i * block_size), block_size, rotation))
      args.state.blocks.append(Block.new((center - 100 - (i * horizontal_offset)).to_i, 100 + (vertical_offset * i) + (i * block_size), block_size, -rotation))
    end
  end
end

#Render loop
def render args
  args.outputs.borders << args.state.game_area
  render_pegs args
  render_blocks args
  args.state.cannon.render args
  args.state.ball.draw args
end

begin :render_methods
  #Draw the pegs in a grid pattern
  def render_pegs args
    args.state.pegs.each do |peg|
      peg.draw args
    end
  end

  def render_blocks args
    args.state.blocks.each do |block|
      block.draw args
    end
  end

end

#Calls all methods necessary for performing calculations
def calc args
  args.state.pegs.each do |peg|
    peg.calc args
  end

  args.state.blocks.each do |block|
    block.calc args
  end

  args.state.ball.update args
  args.state.cannon.update args
end

begin :calc_methods

end

def tick args
  defaults args
  render args
  calc args
end

    Bouncing On Collision - peg.rb link

    # ./samples/04_physics_and_collisions/08_bouncing_on_collision/app/peg.rb
class Peg
  def initialize(x, y, block_size)
    @x = x                    # x cordinate of the LEFT side of the peg
    @y = y                    # y cordinate of the RIGHT side of the peg
    @block_size = block_size  # diameter of the peg

    @radius = @block_size/2.0 # radius of the peg
    @center = {               # cordinatees of the CENTER of the peg
      x: @x+@block_size/2.0,
      y: @y+@block_size/2.0
    }

    @r = 255 # color of the peg
    @g = 0
    @b = 0

    @velocity = {x: 2, y: 0}
  end

  def draw args
    args.outputs.sprites << [ # draw the peg according to the @x, @y, @radius, and the RGB
      @x,
      @y,
      @radius*2.0,
      @radius*2.0,
      "sprites/circle-white.png",
      0,
      255,
      @r,    #r
      @g,    #g
      @b   #b
    ]
  end


  def calc args
    if collisionWithBounce? args # if the is a collision with the bouncing ball
      collide args
      @r = 0
      @b = 0
      @g = 255
    else
    end
  end


  # do two circles (the ball and this peg) intersect
  def collisionWithBounce? args
    squareDistance = (  # the squared distance between the ball's center and this peg's center
      (args.state.ball.center.x - @center.x) ** 2.0 +
      (args.state.ball.center.y - @center.y) ** 2.0
    )
    radiusSum = (  # the sum of the radius squared of the this peg and the ball
      (args.state.ball.radius + @radius) ** 2.0
    )
    # if the squareDistance is less or equal to radiusSum, then there is a radial intersection between the ball and this peg
    return (squareDistance <= radiusSum)
  end

  # ! The following links explain the getRepelMagnitude function !
  # https://raw.githubusercontent.com/DragonRuby/dragonruby-game-toolkit-physics/master/docs/docImages/LinearCollider_4.png
  # https://raw.githubusercontent.com/DragonRuby/dragonruby-game-toolkit-physics/master/docs/docImages/LinearCollider_5.png
  # https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/LinearCollider.md
  def getRepelMagnitude (args, fbx, fby, vrx, vry, ballMag)
    a = fbx ; b = vrx ; c = fby
    d = vry ; e = ballMag
    if b**2 + d**2 == 0
      #unexpected
    end

    x1 = (-a*b+-c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 + d**2 - a**2 * d**2)**0.5)/(b**2 + d**2)
    x2 = -((a*b + c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 * d**2 - a**2 * d**2)**0.5)/(b**2 + d**2))

    err = 0.00001
    o = ((fbx + x1*vrx)**2 + (fby + x1*vry)**2 ) ** 0.5
    p = ((fbx + x2*vrx)**2 + (fby + x2*vry)**2 ) ** 0.5
    r = 0

    if (ballMag >= o-err and ballMag <= o+err)
      r = x1
    elsif (ballMag >= p-err and ballMag <= p+err)
      r = x2
    else
      #unexpected
    end

    if (args.state.ball.center.x > @center.x)
      return x2*-1
    end

    return x2

    #return r
  end

  #this sets the new velocity of the ball once it has collided with this peg
  def collide args
    normalOfRCCollision = [                                                     #this is the normal of the collision in COMPONENT FORM
      {x: @center.x, y: @center.y},                                             #see https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.mathscard.co.uk%2Fonline%2Fcircle-coordinate-geometry%2F&psig=AOvVaw2GcD-e2-nJR_IUKpw3hO98&ust=1605731315521000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCMjBo7e1iu0CFQAAAAAdAAAAABAD
      {x: args.state.ball.center.x, y: args.state.ball.center.y},
    ]

    normalSlope = (                                                             #normalSlope is the slope of normalOfRCCollision
      (normalOfRCCollision[1].y - normalOfRCCollision[0].y) /
      (normalOfRCCollision[1].x - normalOfRCCollision[0].x)
    )
    slope = normalSlope**-1.0 * -1                                              # slope is the slope of the tangent
    # args.state.display_value = slope
    pointA = {                                                                  # pointA and pointB are using the var slope to tangent in COMPONENT FORM
      x: args.state.ball.center.x-1,
      y: -(slope-args.state.ball.center.y)
    }
    pointB = {
      x: args.state.ball.center.x+1,
      y: slope+args.state.ball.center.y
    }

    perpVect = {x: pointB.x - pointA.x, y:pointB.y - pointA.y}                  # perpVect is to be VECTOR of the perpendicular tangent
    mag  = (perpVect.x**2 + perpVect.y**2)**0.5                                 # find the magniude of the perpVect
    perpVect = {x: perpVect.x/(mag), y: perpVect.y/(mag)}                       # divide the perpVect by the magniude to make it a unit vector
    perpVect = {x: -perpVect.y, y: perpVect.x}                                  # swap the x and y and multiply by -1 to make the vector perpendicular
    args.state.display_value = perpVect
    if perpVect.y > 0                                                           #ensure perpVect points upward
      perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
    end

    previousPosition = {                                                        # calculate an ESTIMATE of the previousPosition of the ball
      x:args.state.ball.center.x-args.state.ball.velocity.x,
      y:args.state.ball.center.y-args.state.ball.velocity.y
    }

    yInterc = pointA.y + -slope*pointA.x
    if slope == INFINITY                                                        # the perpVect presently either points in the correct dirrection or it is 180 degrees off we need to correct this
      if previousPosition.x < pointA.x
        perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
        yInterc = -INFINITY
      end
    elsif previousPosition.y < slope*previousPosition.x + yInterc               # check if ball is bellow or above the collider to determine if perpVect is - or +
      perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
    end

    velocityMag =                                                               # the current velocity magnitude of the ball
      (args.state.ball.velocity.x**2 + args.state.ball.velocity.y**2)**0.5
    theta_ball=
      Math.atan2(args.state.ball.velocity.y,args.state.ball.velocity.x)         #the angle of the ball's velocity
    theta_repel=
      Math.atan2(args.state.ball.center.y,args.state.ball.center.x)             #the angle of the repelling force(perpVect)

    fbx = velocityMag * Math.cos(theta_ball)                                    #the x component of the ball's velocity
    fby = velocityMag * Math.sin(theta_ball)                                    #the y component of the ball's velocity
    repelMag = getRepelMagnitude(                                               # the magniude of the collision vector
      args,
      fbx,
      fby,
      perpVect.x,
      perpVect.y,
      (args.state.ball.velocity.x**2 + args.state.ball.velocity.y**2)**0.5
    )
    frx = repelMag* Math.cos(theta_repel)                                       #the x component of the repel's velocity | magnitude is set to twice of fbx
    fry = repelMag* Math.sin(theta_repel)                                       #the y component of the repel's velocity | magnitude is set to twice of fby

    fsumx = fbx+frx                            # sum of x forces
    fsumy = fby+fry                            # sum of y forces
    fr = velocityMag                           # fr is the resulting magnitude
    thetaNew = Math.atan2(fsumy, fsumx)        # thetaNew is the resulting angle
    xnew = fr*Math.cos(thetaNew)               # resulting x velocity
    ynew = fr*Math.sin(thetaNew)               # resulting y velocity
    if (args.state.ball.center.x >= @center.x) # this is necessary for the ball colliding on the right side of the peg
      xnew=xnew.abs
    end

    args.state.ball.velocity.x = xnew                                           # set the x-velocity to the new velocity
    if args.state.ball.center.y > @center.y                                     # if the ball is above the middle of the peg we need to temporarily ignore some of the gravity
      args.state.ball.velocity.y = ynew + GRAVITY * 0.01
    else
      args.state.ball.velocity.y = ynew - GRAVITY * 0.01                        # if the ball is bellow the middle of the peg we need to temporarily increase the power of the gravity
    end

    args.state.ball.center.x+= args.state.ball.velocity.x                       # update the position of the ball so it never looks like the ball is intersecting the circle
    args.state.ball.center.y+= args.state.ball.velocity.y
  end
end

    Bouncing On Collision - vector2d.rb link

    # ./samples/04_physics_and_collisions/08_bouncing_on_collision/app/vector2d.rb
class Vector2d
    attr_accessor :x, :y

    def initialize x=0, y=0
      @x=x
      @y=y
    end

    #returns a vector multiplied by scalar x
    #x [float] scalar
    def mult x
      r = Vector2d.new(0,0)
      r.x=@x*x
      r.y=@y*x
      r
    end

    # vect [Vector2d] vector to copy
    def copy vect
      Vector2d.new(@x, @y)
    end

    #returns a new vector equivalent to this+vect
    #vect [Vector2d] vector to add to self
    def add vect
      Vector2d.new(@x+vect.x,@y+vect.y)
    end

    #returns a new vector equivalent to this-vect
    #vect [Vector2d] vector to subtract to self
    def sub vect
      Vector2d.new(@x-vect.c, @y-vect.y)
    end

    #return the magnitude of the vector
    def mag
      ((@x**2)+(@y**2))**0.5
    end

    #returns a new normalize version of the vector
    def normalize
      Vector2d.new(@x/mag, @y/mag)
    end

    #TODO delet?
    def distABS vect
      (((vect.x-@x)**2+(vect.y-@y)**2)**0.5).abs()
    end
  end

    Arbitrary Collision - ball.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/ball.rb

class Ball
    attr_accessor :velocity, :child, :parent, :number, :leastChain
    attr_reader :x, :y, :hypotenuse, :width, :height

    def initialize args, number, leastChain, parent, child
        #Start the ball in the top center
        @number = number
        @leastChain = leastChain
        @x = args.grid.w / 2
        @y = args.grid.h - 20

        @velocity = Vector2d.new(2, -2)
        @width =  10
        @height = 10

        @left_wall = (args.state.board_width + args.grid.w / 8)
        @right_wall = @left_wall + args.state.board_width

        @max_velocity = MAX_VELOCITY

        @child = child
        @parent = parent

        @past = [{x: @x, y: @y}]
        @next = nil
    end

    def reassignLeastChain (lc=nil)
      if (lc == nil)
        lc = @number
      end
      @leastChain = lc
      if (parent != nil)
        @parent.reassignLeastChain(lc)
      end

    end

    def makeLeader args
      if isLeader
        return
      end
      @parent.reassignLeastChain
      args.state.ballParents.push(self)
      @parent = nil

    end

    def isLeader
      return (parent == nil)
    end

    def receiveNext (p)
      #trace!
      if parent != nil
        @x = p[:x]
        @y = p[:y]
        @velocity = p[:velocity]
        #puts @x.to_s + "|" + @y.to_s + "|"[email protected]_s
        @past.append(p)
        if (@past.length >= BALL_DISTANCE)
          if (@child != nil)
            @child.receiveNext(@past[0])
            @past.shift
          end
        end
      end
    end

    #Move the ball according to its velocity
    def update args

        if isLeader
          wallBounds args
          @x += @velocity.x
          @y += @velocity.y
          @past.append({x: @x, y: @y, velocity: @velocity})
          #puts @past

          if (@past.length >= BALL_DISTANCE)
            if (@child != nil)
              @child.receiveNext(@past[0])
              @past.shift
            end
          end

        else
          puts "unexpected"
          raise "unexpected"
        end
    end

    def wallBounds args
        b= false
        if @x < @left_wall
          @velocity.x = @velocity.x.abs() * 1
          b=true
        elsif @x + @width > @right_wall
          @velocity.x = @velocity.x.abs() * -1
          b=true
        end
        if @y < 0
          @velocity.y = @velocity.y.abs() * 1
          b=true
        elsif @y + @height > args.grid.h
          @velocity.y = @velocity.y.abs() * -1
          b=true
        end
        mag = (@velocity.x**2.0 + @velocity.y**2.0)**0.5
        if (b == true && mag < MAX_VELOCITY)
          @velocity.x*=1.1;
          @velocity.y*=1.1;
        end

    end

    #render the ball to the screen
    def draw args

        #update args
        #args.outputs.solids << [@x, @y, @width, @height, 255, 255, 0];
        #args.outputs.sprits << {
          #x: @x,
          #y: @y,
          #w: @width,
          #h: @height,
          #path: "sprites/ball10.png"
        #}
        #args.outputs.sprites <<[@x, @y, @width, @height, "sprites/ball10.png"]
        args.outputs.sprites << {x: @x, y: @y, w: @width, h: @height, path:"sprites/ball10.png" }
    end

    def getDraw args
      #wallBounds args
      #update args
      #args.outputs.labels << [@x, @y, @number.to_s + "|" + @leastChain.to_s]
      return [@x, @y, @width, @height, "sprites/ball10.png"]
    end

    def getPoints args
      points = [
        {x:@x+@width/2, y: @y},
        {x:@x+@width, y:@y+@height/2},
        {x:@x+@width/2,y:@y+@height},
        {x:@x,y:@y+@height/2}
      ]
      #psize = 5.0
      #for p in points
        #args.outputs.solids << [p.x-psize/2.0, p.y-psize/2.0, psize, psize, 0, 0, 0];
      #end
      return points
    end

    def serialize
      {x: @x, y:@y}
    end

    def inspect
      serialize.to_s
    end

    def to_s
      serialize.to_s
    end
  end

    Arbitrary Collision - blocks.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/blocks.rb
MAX_COUNT=100

def universalUpdateOne args, shape
  didHit = false
  hitters = []
  #puts shape.to_s
  toCollide = nil
  for b in args.state.balls
    if [b.x, b.y, b.width, b.height].intersect_rect?(shape.bold)
      didSquare = false
      for s in shape.squareColliders
        if (s.collision?(args, b))
          didSquare = true
          didHit = true
          #s.collide(args, b)
          toCollide = s
          #hitter = b
          hitters.append(b)
        end #end if
      end #end for
      if (didSquare == false)
        for c in shape.colliders
          #puts args.state.ball.velocity
          if c.collision?(args, b.getPoints(args),b)
            #c.collide args, b
            toCollide = c
            didHit = true
            hitters.append(b)
          end #end if
        end #end for
      end #end if
    end#end if
  end#end for
  if (didHit)
    shape.count=0
    hitters = hitters.uniq
    for hitter in hitters
      hitter.makeLeader args
      #toCollide.collide(args, hitter)
      if shape.home == "squares"
        args.state.squares.delete(shape)
      elsif shape.home == "tshapes"
        args.state.tshapes.delete(shape)
      else shape.home == "lines"
        args.state.lines.delete(shape)
      end
    end

    #puts "HIT!" + hitter.number
  end
end

def universalUpdate args, shape
  #puts shape.home
  if (shape.count <= 1)
    universalUpdateOne args, shape
    return
  end

  didHit = false
  hitter = nil
  for b in args.state.ballParents
    if [b.x, b.y, b.width, b.height].intersect_rect?(shape.bold)
      didSquare = false
      for s in shape.squareColliders
        if (s.collision?(args, b))
          didSquare = true
          didHit = true
          s.collide(args, b)
          hitter = b
        end
      end
      if (didSquare == false)
        for c in shape.colliders
          #puts args.state.ball.velocity
          if c.collision?(args, b.getPoints(args),b)
            c.collide args, b
            didHit = true
            hitter = b
          end
        end
      end
    end
  end
  if (didHit)
    shape.count=shape.count-1
    shape.damageCount.append([(hitter.leastChain+1 - hitter.number)-1, args.state.tick_count])

  end
  i=0
  while i < shape.damageCount.length
    if shape.damageCount[i][0] <= 0
      shape.damageCount.delete_at(i)
      i-=1
    elsif shape.damageCount[i][1].elapsed_time > BALL_DISTANCE and shape.damageCount[i][0] > 1
      shape.count-=1
      shape.damageCount[i][0]-=1
      shape.damageCount[i][1] = args.state.tick_count
    end
    i+=1
  end
end


class Square
   attr_accessor :count, :x, :y, :home, :bold, :squareColliders, :colliders, :damageCount
   def initialize(args, x, y, block_size, orientation, block_offset)
        @x = x * block_size
        @y = y * block_size
        @block_size = block_size
        @block_offset = block_offset
        @orientation = orientation
        @damageCount = []
        @home = 'squares'


        Kernel.srand()
        @r = rand(255)
        @g = rand(255)
        @b = rand(255)

        @count = rand(MAX_COUNT)+1

        x_offset = (args.state.board_width + args.grid.w / 8) + @block_offset / 2
        @x_adjusted = @x + x_offset
        @y_adjusted = @y
        @size_adjusted = @block_size * 2 - @block_offset

        hypotenuse=args.state.ball_hypotenuse
        @bold = [(@x_adjusted-hypotenuse/2)-1, (@y_adjusted-hypotenuse/2)-1, @size_adjusted + hypotenuse + 2, @size_adjusted + hypotenuse + 2]

        @points = [
          {x:@x_adjusted, y:@y_adjusted},
          {x:@x_adjusted+@size_adjusted, y:@y_adjusted},
          {x:@x_adjusted+@size_adjusted, y:@y_adjusted+@size_adjusted},
          {x:@x_adjusted, y:@y_adjusted+@size_adjusted}
        ]
        @squareColliders = [
          SquareCollider.new(@points[0].x,@points[0].y,{x:-1,y:-1}),
          SquareCollider.new(@points[1].x-COLLISIONWIDTH,@points[1].y,{x:1,y:-1}),
          SquareCollider.new(@points[2].x-COLLISIONWIDTH,@points[2].y-COLLISIONWIDTH,{x:1,y:1}),
          SquareCollider.new(@points[3].x,@points[3].y-COLLISIONWIDTH,{x:-1,y:1}),
        ]
        @colliders = [
          LinearCollider.new(@points[0],@points[1], :neg),
          LinearCollider.new(@points[1],@points[2], :neg),
          LinearCollider.new(@points[2],@points[3], :pos),
          LinearCollider.new(@points[0],@points[3], :pos)
        ]
   end

   def draw(args)
    #Offset the coordinates to the edge of the game area
    x_offset = (args.state.board_width + args.grid.w / 8) + @block_offset / 2
    #args.outputs.solids << [@x + x_offset, @y, @block_size * 2 - @block_offset, @block_size * 2 - @block_offset, @r, @g, @b]
    args.outputs.solids <<{x: (@x + x_offset), y: (@y), w: (@block_size * 2 - @block_offset), h: (@block_size * 2 - @block_offset), r: @r , g: @g , b: @b }
    #args.outputs.solids << @bold.append([255,0,0])
    args.outputs.labels << [@x + x_offset + (@block_size * 2 - @block_offset)/2, (@y) + (@block_size * 2 - @block_offset)/2, @count.to_s]

   end

   def update args
     universalUpdate args, self
   end
end

class TShape
    attr_accessor :count, :x, :y, :home, :bold, :squareColliders, :colliders, :damageCount
    def initialize(args, x, y, block_size, orientation, block_offset)
        @x = x * block_size
        @y = y * block_size
        @block_size = block_size
        @block_offset = block_offset
        @orientation = orientation
        @damageCount = []
        @home = "tshapes"

        Kernel.srand()
        @r = rand(255)
        @g = rand(255)
        @b = rand(255)

        @count = rand(MAX_COUNT)+1


        @shapePoints = getShapePoints(args)
        minX={x:INFINITY, y:0}
        minY={x:0, y:INFINITY}
        maxX={x:-INFINITY, y:0}
        maxY={x:0, y:-INFINITY}
        for p in @shapePoints
          if p.x < minX.x
            minX = p
          end
          if p.x > maxX.x
            maxX = p
          end
          if p.y < minY.y
            minY = p
          end
          if p.y > maxY.y
            maxY = p
          end
        end


        hypotenuse=args.state.ball_hypotenuse

        @bold = [(minX.x-hypotenuse/2)-1, (minY.y-hypotenuse/2)-1, -((minX.x-hypotenuse/2)-1)+(maxX.x + hypotenuse + 2), -((minY.y-hypotenuse/2)-1)+(maxY.y + hypotenuse + 2)]
    end
    def getShapePoints(args)
      points=[]
      x_offset = (args.state.board_width + args.grid.w / 8) + (@block_offset / 2)

      if @orientation == :right
          #args.outputs.solids << [@x + x_offset, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
          #args.outputs.solids << [@x + x_offset, @y + @block_size, @block_size * 2, @block_size, @r, @g, @b]
          points = [
            {x:@x + x_offset, y:@y},
            {x:(@x + x_offset)+(@block_size - @block_offset), y:@y},
            {x:(@x + x_offset)+(@block_size - @block_offset),y:@y + @block_size},
            {x:(@x + x_offset)+ @block_size * 2,y:@y + @block_size},
            {x:(@x + x_offset)+ @block_size * 2,y:@y + @block_size+@block_size},
            {x:(@x + x_offset)+(@block_size - @block_offset),y:@y + @block_size+@block_size},
            {x:(@x + x_offset)+(@block_size - @block_offset), y:@y+ @block_size * 3 - @block_offset},
            {x:@x + x_offset , y:@y+ @block_size * 3 - @block_offset}
          ]
          @squareColliders = [
            SquareCollider.new(points[0].x,points[0].y,{x:-1,y:-1}),
            SquareCollider.new(points[1].x-COLLISIONWIDTH,points[1].y,{x:1,y:-1}),
            SquareCollider.new(points[2].x,points[2].y-COLLISIONWIDTH,{x:1,y:-1}),
            SquareCollider.new(points[3].x-COLLISIONWIDTH,points[3].y,{x:1,y:-1}),
            SquareCollider.new(points[4].x-COLLISIONWIDTH,points[4].y-COLLISIONWIDTH,{x:1,y:1}),
            SquareCollider.new(points[5].x,points[5].y,{x:1,y:1}),
            SquareCollider.new(points[6].x-COLLISIONWIDTH,points[6].y-COLLISIONWIDTH,{x:1,y:1}),
            SquareCollider.new(points[7].x,points[7].y-COLLISIONWIDTH,{x:-1,y:1}),
          ]
          @colliders = [
            LinearCollider.new(points[0],points[1], :neg),
            LinearCollider.new(points[1],points[2], :neg),
            LinearCollider.new(points[2],points[3], :neg),
            LinearCollider.new(points[3],points[4], :neg),
            LinearCollider.new(points[4],points[5], :pos),
            LinearCollider.new(points[5],points[6], :neg),
            LinearCollider.new(points[6],points[7], :pos),
            LinearCollider.new(points[0],points[7], :pos)
          ]
      elsif @orientation == :up
          #args.outputs.solids << [@x + x_offset, @y, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
          #args.outputs.solids << [@x + x_offset + @block_size, @y, @block_size, @block_size * 2, @r, @g, @b]
          points = [
            {x:@x + x_offset, y:@y},
            {x:(@x + x_offset)+(@block_size * 3 - @block_offset), y:@y},
            {x:(@x + x_offset)+(@block_size * 3 - @block_offset), y:@y+(@block_size - @block_offset)},
            {x:@x + x_offset + @block_size + @block_size, y:@y+(@block_size - @block_offset)},
            {x:@x + x_offset + @block_size + @block_size, y:@y+@block_size*2},
            {x:@x + x_offset + @block_size, y:@y+@block_size*2},
            {x:@x + x_offset + @block_size, y:@y+(@block_size - @block_offset)},
            {x:@x + x_offset, y:@y+(@block_size - @block_offset)}
          ]
          @squareColliders = [
            SquareCollider.new(points[0].x,points[0].y,{x:-1,y:-1}),
            SquareCollider.new(points[1].x-COLLISIONWIDTH,points[1].y,{x:1,y:-1}),
            SquareCollider.new(points[2].x-COLLISIONWIDTH,points[2].y-COLLISIONWIDTH,{x:1,y:1}),
            SquareCollider.new(points[3].x,points[3].y,{x:1,y:1}),
            SquareCollider.new(points[4].x-COLLISIONWIDTH,points[4].y-COLLISIONWIDTH,{x:1,y:1}),
            SquareCollider.new(points[5].x,points[5].y-COLLISIONWIDTH,{x:-1,y:1}),
            SquareCollider.new(points[6].x-COLLISIONWIDTH,points[6].y,{x:-1,y:1}),
            SquareCollider.new(points[7].x,points[7].y-COLLISIONWIDTH,{x:-1,y:1}),
          ]
          @colliders = [
            LinearCollider.new(points[0],points[1], :neg),
            LinearCollider.new(points[1],points[2], :neg),
            LinearCollider.new(points[2],points[3], :pos),
            LinearCollider.new(points[3],points[4], :neg),
            LinearCollider.new(points[4],points[5], :pos),
            LinearCollider.new(points[5],points[6], :neg),
            LinearCollider.new(points[6],points[7], :pos),
            LinearCollider.new(points[0],points[7], :pos)
          ]
      elsif @orientation == :left
          #args.outputs.solids << [@x + x_offset + @block_size, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
          #args.outputs.solids << [@x + x_offset, @y + @block_size, @block_size * 2 - @block_offset, @block_size - @block_offset, @r, @g, @b]
          xh = @x + x_offset
          #points = [
            #{x:@x + x_offset, y:@y},
            #{x:(@x + x_offset)+(@block_size - @block_offset), y:@y},
            #{x:(@x + x_offset)+(@block_size - @block_offset),y:@y + @block_size},
            #{x:(@x + x_offset)+ @block_size * 2,y:@y + @block_size},
            #{x:(@x + x_offset)+ @block_size * 2,y:@y + @block_size+@block_size},
            #{x:(@x + x_offset)+(@block_size - @block_offset),y:@y + @block_size+@block_size},
            #{x:(@x + x_offset)+(@block_size - @block_offset), y:@y+ @block_size * 3 - @block_offset},
            #{x:@x + x_offset , y:@y+ @block_size * 3 - @block_offset}
          #]
          points = [
            {x:@x + x_offset + @block_size, y:@y},
            {x:@x + x_offset + @block_size + (@block_size - @block_offset), y:@y},
            {x:@x + x_offset + @block_size + (@block_size - @block_offset),y:@y+@block_size*3- @block_offset},
            {x:@x + x_offset + @block_size, y:@y+@block_size*3- @block_offset},
            {x:@x + x_offset+@block_size, y:@y+@block_size*2- @block_offset},
            {x:@x + x_offset, y:@y+@block_size*2- @block_offset},
            {x:@x + x_offset, y:@y+@block_size},
            {x:@x + x_offset+@block_size, y:@y+@block_size}
          ]
          @squareColliders = [
            SquareCollider.new(points[0].x,points[0].y,{x:-1,y:-1}),
            SquareCollider.new(points[1].x-COLLISIONWIDTH,points[1].y,{x:1,y:-1}),
            SquareCollider.new(points[2].x-COLLISIONWIDTH,points[2].y-COLLISIONWIDTH,{x:1,y:1}),
            SquareCollider.new(points[3].x,points[3].y-COLLISIONWIDTH,{x:-1,y:1}),
            SquareCollider.new(points[4].x-COLLISIONWIDTH,points[4].y,{x:-1,y:1}),
            SquareCollider.new(points[5].x,points[5].y-COLLISIONWIDTH,{x:-1,y:1}),
            SquareCollider.new(points[6].x,points[6].y,{x:-1,y:-1}),
            SquareCollider.new(points[7].x-COLLISIONWIDTH,points[7].y-COLLISIONWIDTH,{x:-1,y:-1}),
          ]
          @colliders = [
            LinearCollider.new(points[0],points[1], :neg),
            LinearCollider.new(points[1],points[2], :neg),
            LinearCollider.new(points[2],points[3], :pos),
            LinearCollider.new(points[3],points[4], :neg),
            LinearCollider.new(points[4],points[5], :pos),
            LinearCollider.new(points[5],points[6], :neg),
            LinearCollider.new(points[6],points[7], :neg),
            LinearCollider.new(points[0],points[7], :pos)
          ]
      elsif @orientation == :down
          #args.outputs.solids << [@x + x_offset, @y + @block_size, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
          #args.outputs.solids << [@x + x_offset + @block_size, @y, @block_size - @block_offset, @block_size * 2 - @block_offset, @r, @g, @b]

          points = [
            {x:@x + x_offset, y:@y+(@block_size*2)-@block_offset},
            {x:@x + x_offset+ @block_size*3-@block_offset, y:@y+(@block_size*2)-@block_offset},
            {x:@x + x_offset+ @block_size*3-@block_offset, y:@y+(@block_size)},
            {x:@x + x_offset+ @block_size*2-@block_offset, y:@y+(@block_size)},
            {x:@x + x_offset+ @block_size*2-@block_offset, y:@y},#
            {x:@x + x_offset+ @block_size, y:@y},#
            {x:@x + x_offset + @block_size, y:@y+(@block_size)},
            {x:@x + x_offset, y:@y+(@block_size)}
          ]
          @squareColliders = [
            SquareCollider.new(points[0].x,points[0].y-COLLISIONWIDTH,{x:-1,y:1}),
            SquareCollider.new(points[1].x-COLLISIONWIDTH,points[1].y-COLLISIONWIDTH,{x:1,y:1}),
            SquareCollider.new(points[2].x-COLLISIONWIDTH,points[2].y,{x:1,y:-1}),
            SquareCollider.new(points[3].x,points[3].y-COLLISIONWIDTH,{x:1,y:-1}),
            SquareCollider.new(points[4].x-COLLISIONWIDTH,points[4].y,{x:1,y:-1}),
            SquareCollider.new(points[5].x,points[5].y,{x:-1,y:-1}),
            SquareCollider.new(points[6].x-COLLISIONWIDTH,points[6].y-COLLISIONWIDTH,{x:-1,y:-1}),
            SquareCollider.new(points[7].x,points[7].y,{x:-1,y:-1}),
          ]
          @colliders = [
            LinearCollider.new(points[0],points[1], :pos),
            LinearCollider.new(points[1],points[2], :pos),
            LinearCollider.new(points[2],points[3], :neg),
            LinearCollider.new(points[3],points[4], :pos),
            LinearCollider.new(points[4],points[5], :neg),
            LinearCollider.new(points[5],points[6], :pos),
            LinearCollider.new(points[6],points[7], :neg),
            LinearCollider.new(points[0],points[7], :neg)
          ]
      end
      return points
    end

    def draw(args)
        #Offset the coordinates to the edge of the game area
        x_offset = (args.state.board_width + args.grid.w / 8) + (@block_offset / 2)

        if @orientation == :right
            #args.outputs.solids << [@x + x_offset, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset), y: @y, w: @block_size - @block_offset, h: (@block_size * 3 - @block_offset), r: @r , g: @g, b: @b}
            #args.outputs.solids << [@x + x_offset, @y + @block_size, @block_size * 2, @block_size, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset), y: (@y + @block_size), w: (@block_size * 2), h: (@block_size), r: @r , g: @g, b: @b }
        elsif @orientation == :up
            #args.outputs.solids << [@x + x_offset, @y, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset), y: (@y), w: (@block_size * 3 - @block_offset), h: (@block_size - @block_offset), r: @r , g: @g, b: @b}
            #args.outputs.solids << [@x + x_offset + @block_size, @y, @block_size, @block_size * 2, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset + @block_size), y: (@y), w: (@block_size), h: (@block_size * 2), r: @r , g: @g, b: @b}
        elsif @orientation == :left
            #args.outputs.solids << [@x + x_offset + @block_size, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset + @block_size), y: (@y), w: (@block_size - @block_offset), h: (@block_size * 3 - @block_offset), r: @r , g: @g, b: @b}
            #args.outputs.solids << [@x + x_offset, @y + @block_size, @block_size * 2 - @block_offset, @block_size - @block_offset, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset), y: (@y + @block_size), w: (@block_size * 2 - @block_offset), h: (@block_size - @block_offset), r: @r , g: @g, b: @b}
        elsif @orientation == :down
            #args.outputs.solids << [@x + x_offset, @y + @block_size, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset), y: (@y + @block_size), w: (@block_size * 3 - @block_offset), h: (@block_size - @block_offset), r: @r , g: @g, b: @b}
            #args.outputs.solids << [@x + x_offset + @block_size, @y, @block_size - @block_offset, @block_size * 2 - @block_offset, @r, @g, @b]
            args.outputs.solids << {x: (@x + x_offset + @block_size), y: (@y), w: (@block_size - @block_offset), h: ( @block_size * 2 - @block_offset), r: @r , g: @g, b: @b}
        end

        #psize = 5.0
        #for p in @shapePoints
          #args.outputs.solids << [p.x-psize/2, p.y-psize/2, psize, psize, 0, 0, 0]
        #end
        args.outputs.labels << [@x + x_offset + (@block_size * 2 - @block_offset)/2, (@y) + (@block_size * 2 - @block_offset)/2, @count.to_s]

    end

    def updateOne_old args
      didHit = false
      hitter = nil
      toCollide = nil
      for b in args.state.balls
        if [b.x, b.y, b.width, b.height].intersect_rect?(@bold)
          didSquare = false
          for s in @squareColliders
            if (s.collision?(args, b))
              didSquare = true
              didHit = true
              #s.collide(args, b)
              toCollide = s
              hitter = b
              break
            end
          end
          if (didSquare == false)
            for c in @colliders
              #puts args.state.ball.velocity
              if c.collision?(args, b.getPoints(args),b)
                #c.collide args, b
                toCollide = c
                didHit = true
                hitter = b
                break
              end
            end
          end
        end
        if didHit
          break
        end
      end
      if (didHit)
        @count=0
        hitter.makeLeader args
        #toCollide.collide(args, hitter)
        args.state.tshapes.delete(self)
        #puts "HIT!" + hitter.number
      end
    end

    def update_old args
      if (@count == 1)
        updateOne args
        return
      end
      didHit = false
      hitter = nil
      for b in args.state.ballParents
        if [b.x, b.y, b.width, b.height].intersect_rect?(@bold)
          didSquare = false
          for s in @squareColliders
            if (s.collision?(args, b))
              didSquare = true
              didHit=true
              s.collide(args, b)
              hitter = b
            end
          end
          if (didSquare == false)
            for c in @colliders
              #puts args.state.ball.velocity
              if c.collision?(args, b.getPoints(args), b)
                c.collide args, b
                didHit=true
                hitter = b
              end
            end
          end
        end
      end
      if (didHit)
        @count=@count-1
        @damageCount.append([(hitter.leastChain+1 - hitter.number)-1, args.state.tick_count])

        if (@count == 0)
          args.state.tshapes.delete(self)
          return
        end
      end
      i=0

      while i < @damageCount.length
        if @damageCount[i][0] <= 0
          @damageCount.delete_at(i)
          i-=1
        elsif @damageCount[i][1].elapsed_time > BALL_DISTANCE
          @count-=1
          @damageCount[i][0]-=1
        end
        if (@count == 0)
          args.state.tshapes.delete(self)
          return
        end
        i+=1
      end
    end #end update

    def update args
      universalUpdate args, self
    end

end

class Line
    attr_accessor :count, :x, :y, :home, :bold, :squareColliders, :colliders, :damageCount
    def initialize(args, x, y, block_size, orientation, block_offset)
        @x = x * block_size
        @y = y * block_size
        @block_size = block_size
        @block_offset = block_offset
        @orientation = orientation
        @damageCount = []
        @home = "lines"

        Kernel.srand()
        @r = rand(255)
        @g = rand(255)
        @b = rand(255)

        @count = rand(MAX_COUNT)+1

        @shapePoints = getShapePoints(args)
        minX={x:INFINITY, y:0}
        minY={x:0, y:INFINITY}
        maxX={x:-INFINITY, y:0}
        maxY={x:0, y:-INFINITY}
        for p in @shapePoints
          if p.x < minX.x
            minX = p
          end
          if p.x > maxX.x
            maxX = p
          end
          if p.y < minY.y
            minY = p
          end
          if p.y > maxY.y
            maxY = p
          end
        end


        hypotenuse=args.state.ball_hypotenuse

        @bold = [(minX.x-hypotenuse/2)-1, (minY.y-hypotenuse/2)-1, -((minX.x-hypotenuse/2)-1)+(maxX.x + hypotenuse + 2), -((minY.y-hypotenuse/2)-1)+(maxY.y + hypotenuse + 2)]
    end

    def getShapePoints(args)
      points=[]
      x_offset = (args.state.board_width + args.grid.w / 8) + (@block_offset / 2)

      if @orientation == :right
        #args.outputs.solids << [@x + x_offset, @y, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
        xa =@x + x_offset
        ya =@y
        wa =@block_size * 3 - @block_offset
        ha =(@block_size - @block_offset)
      elsif @orientation == :up
        #args.outputs.solids << [@x + x_offset, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
        xa =@x + x_offset
        ya =@y
        wa =@block_size - @block_offset
        ha =@block_size * 3 - @block_offset

      elsif @orientation == :left
        #args.outputs.solids << [@x + x_offset, @y, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
        xa =@x + x_offset
        ya =@y
        wa =@block_size * 3 - @block_offset
        ha =@block_size - @block_offset
      elsif @orientation == :down
        #args.outputs.solids << [@x + x_offset, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
        xa =@x + x_offset
        ya =@y
        wa =@block_size - @block_offset
        ha =@block_size * 3 - @block_offset
      end
      points = [
        {x: xa, y:ya},
        {x: xa + wa,y:ya},
        {x: xa + wa,y:ya+ha},
        {x: xa, y:ya+ha},
      ]
      @squareColliders = [
        SquareCollider.new(points[0].x,points[0].y,{x:-1,y:-1}),
        SquareCollider.new(points[1].x-COLLISIONWIDTH,points[1].y,{x:1,y:-1}),
        SquareCollider.new(points[2].x-COLLISIONWIDTH,points[2].y-COLLISIONWIDTH,{x:1,y:1}),
        SquareCollider.new(points[3].x,points[3].y-COLLISIONWIDTH,{x:-1,y:1}),
      ]
      @colliders = [
        LinearCollider.new(points[0],points[1], :neg),
        LinearCollider.new(points[1],points[2], :neg),
        LinearCollider.new(points[2],points[3], :pos),
        LinearCollider.new(points[0],points[3], :pos),
      ]
      return points
    end

    def update args
      universalUpdate args, self
    end

    def draw(args)
        x_offset = (args.state.board_width + args.grid.w / 8) + @block_offset / 2

        if @orientation == :right
            args.outputs.solids << [@x + x_offset, @y, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
        elsif @orientation == :up
            args.outputs.solids << [@x + x_offset, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
        elsif @orientation == :left
            args.outputs.solids << [@x + x_offset, @y, @block_size * 3 - @block_offset, @block_size - @block_offset, @r, @g, @b]
        elsif @orientation == :down
            args.outputs.solids << [@x + x_offset, @y, @block_size - @block_offset, @block_size * 3 - @block_offset, @r, @g, @b]
        end

        args.outputs.labels << [@x + x_offset + (@block_size * 2 - @block_offset)/2, (@y) + (@block_size * 2 - @block_offset)/2, @count.to_s]

    end
end

    Arbitrary Collision - linear_collider.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/linear_collider.rb

COLLISIONWIDTH=8

class LinearCollider
  attr_reader :pointA, :pointB
  def initialize (pointA, pointB, mode,collisionWidth=COLLISIONWIDTH)
    @pointA = pointA
    @pointB = pointB
    @mode = mode
    @collisionWidth = collisionWidth

    if (@pointA.x > @pointB.x)
      @pointA, @pointB = @pointB, @pointA
    end

    @linearCollider_collision_once = false
  end

  def collisionSlope args
    if (@[email protected] == 0)
      return INFINITY
    end
    return (@pointB.y - @pointA.y) / (@pointB.x - @pointA.x)
  end


  def collision? (args, points, ball=nil)

    slope = collisionSlope args
    result = false

    # calculate a vector with a magnitude of (1/2)collisionWidth and a direction perpendicular to the collision line
    vect=nil;mag=nil;vect=nil;
    if @mode == :both
      vect = {x: @pointB.x - @pointA.x, y:@pointB.y - @pointA.y}
      mag  = (vect.x**2 + vect.y**2)**0.5
      vect = {y: -1*(vect.x/(mag))*@collisionWidth*0.5, x: (vect.y/(mag))*@collisionWidth*0.5}
    else
      vect = {x: @pointB.x - @pointA.x, y:@pointB.y - @pointA.y}
      mag  = (vect.x**2 + vect.y**2)**0.5
      vect = {y: -1*(vect.x/(mag))*@collisionWidth, x: (vect.y/(mag))*@collisionWidth}
    end

    rpointA=nil;rpointB=nil;rpointC=nil;rpointD=nil;
    if @mode == :pos
      rpointA = {x:@pointA.x + vect.x, y:@pointA.y + vect.y}
      rpointB = {x:@pointB.x + vect.x, y:@pointB.y + vect.y}
      rpointC = {x:@pointB.x, y:@pointB.y}
      rpointD = {x:@pointA.x, y:@pointA.y}
    elsif @mode == :neg
      rpointA = {x:@pointA.x, y:@pointA.y}
      rpointB = {x:@pointB.x, y:@pointB.y}
      rpointC = {x:@pointB.x - vect.x, y:@pointB.y - vect.y}
      rpointD = {x:@pointA.x - vect.x, y:@pointA.y - vect.y}
    elsif @mode == :both
      rpointA = {x:@pointA.x + vect.x, y:@pointA.y + vect.y}
      rpointB = {x:@pointB.x + vect.x, y:@pointB.y + vect.y}
      rpointC = {x:@pointB.x - vect.x, y:@pointB.y - vect.y}
      rpointD = {x:@pointA.x - vect.x, y:@pointA.y - vect.y}
    end
    #four point rectangle



    if ball != nil
      xs = [rpointA.x,rpointB.x,rpointC.x,rpointD.x]
      ys = [rpointA.y,rpointB.y,rpointC.y,rpointD.y]
      correct = 1
      rect1 = [ball.x, ball.y, ball.width, ball.height]
      #$r1 = rect1
      rect2 = [xs.min-correct,ys.min-correct,(xs.max-xs.min)+correct*2,(ys.max-ys.min)+correct*2]
      #$r2 = rect2
      if rect1.intersect_rect?(rect2) == false
        return false
      end
    end


    #area of a triangle
    triArea = -> (a,b,c) { ((a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y))/2.0).abs }

    #if at least on point is in the rectangle then collision? is true - otherwise false
    for point in points
      #Check whether a given point lies inside a rectangle or not:
      #if the sum of the area of traingls, PAB, PBC, PCD, PAD equal the area of the rec, then an intersection has occured
      areaRec =  triArea.call(rpointA, rpointB, rpointC)+triArea.call(rpointA, rpointC, rpointD)
      areaSum = [
        triArea.call(point, rpointA, rpointB),triArea.call(point, rpointB, rpointC),
        triArea.call(point, rpointC, rpointD),triArea.call(point, rpointA, rpointD)
      ].inject(0){|sum,x| sum + x }
      e = 0.0001 #allow for minor error
      if areaRec>= areaSum-e and areaRec<= areaSum+e
        result = true
        #return true
        break
      end
    end

    #args.outputs.lines << [@pointA.x, @pointA.y, @pointB.x, @pointB.y,     000, 000, 000]
    #args.outputs.lines << [rpointA.x, rpointA.y, rpointB.x, rpointB.y,     255, 000, 000]
    #args.outputs.lines << [rpointC.x, rpointC.y, rpointD.x, rpointD.y,     000, 000, 255]


    #puts (rpointA.x.to_s + " " +  rpointA.y.to_s + " " + rpointB.x.to_s + " "+ rpointB.y.to_s)
    return result
  end #end collision?

  def getRepelMagnitude (fbx, fby, vrx, vry, ballMag)
    a = fbx ; b = vrx ; c = fby
    d = vry ; e = ballMag
    if b**2 + d**2 == 0
      #unexpected
    end
    x1 = (-a*b+-c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 + d**2 - a**2 * d**2)**0.5)/(b**2 + d**2)
    x2 = -((a*b + c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 * d**2 - a**2 * d**2)**0.5)/(b**2 + d**2))
    err = 0.00001
    o = ((fbx + x1*vrx)**2 + (fby + x1*vry)**2 ) ** 0.5
    p = ((fbx + x2*vrx)**2 + (fby + x2*vry)**2 ) ** 0.5
    r = 0
    if (ballMag >= o-err and ballMag <= o+err)
      r = x1
    elsif (ballMag >= p-err and ballMag <= p+err)
      r = x2
    else
      #unexpected
    end
    return r
  end

  def collide args, ball
    slope = collisionSlope args

    # perpVect: normal vector perpendicular to collision
    perpVect = {x: @pointB.x - @pointA.x, y:@pointB.y - @pointA.y}
    mag  = (perpVect.x**2 + perpVect.y**2)**0.5
    perpVect = {x: perpVect.x/(mag), y: perpVect.y/(mag)}
    perpVect = {x: -perpVect.y, y: perpVect.x}
    if perpVect.y > 0 #ensure perpVect points upward
      perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
    end
    previousPosition = {
      x:ball.x-ball.velocity.x,
      y:ball.y-ball.velocity.y
    }
    yInterc = @pointA.y + -slope*@pointA.x
    if slope == INFINITY
      if previousPosition.x < @pointA.x
        perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
        yInterc = -INFINITY
      end
    elsif previousPosition.y < slope*previousPosition.x + yInterc #check if ball is bellow or above the collider to determine if perpVect is - or +
      perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
    end

    velocityMag = (ball.velocity.x**2 + ball.velocity.y**2)**0.5
    theta_ball=Math.atan2(ball.velocity.y,ball.velocity.x) #the angle of the ball's velocity
    theta_repel=Math.atan2(perpVect.y,perpVect.x) #the angle of the repelling force(perpVect)

    fbx = velocityMag * Math.cos(theta_ball) #the x component of the ball's velocity
    fby = velocityMag * Math.sin(theta_ball) #the y component of the ball's velocity

    #the magnitude of the repelling force
    repelMag = getRepelMagnitude(fbx, fby, perpVect.x, perpVect.y, (ball.velocity.x**2 + ball.velocity.y**2)**0.5)
    frx = repelMag* Math.cos(theta_repel) #the x component of the repel's velocity | magnitude is set to twice of fbx
    fry = repelMag* Math.sin(theta_repel) #the y component of the repel's velocity | magnitude is set to twice of fby

    fsumx = fbx+frx #sum of x forces
    fsumy = fby+fry #sum of y forces
    fr = velocityMag#fr is the resulting magnitude
    thetaNew = Math.atan2(fsumy, fsumx)  #thetaNew is the resulting angle
    xnew = fr*Math.cos(thetaNew)#resulting x velocity
    ynew = fr*Math.sin(thetaNew)#resulting y velocity
    if (velocityMag < MAX_VELOCITY)
      ball.velocity =  Vector2d.new(xnew*1.1, ynew*1.1)
    else
      ball.velocity =  Vector2d.new(xnew, ynew)
    end

  end
end

    Arbitrary Collision - main.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/main.rb
INFINITY= 10**10
MAX_VELOCITY = 8.0
BALL_COUNT = 90
BALL_DISTANCE = 20
require 'app/vector2d.rb'
require 'app/blocks.rb'
require 'app/ball.rb'
require 'app/rectangle.rb'
require 'app/linear_collider.rb'
require 'app/square_collider.rb'



#Method to init default values
def defaults args
  args.state.board_width ||= args.grid.w / 4
  args.state.board_height ||= args.grid.h
  args.state.game_area ||= [(args.state.board_width + args.grid.w / 8), 0, args.state.board_width, args.grid.h]
  args.state.balls ||= []
  args.state.num_balls ||= 0
  args.state.ball_created_at ||= args.state.tick_count
  args.state.ball_hypotenuse = (10**2 + 10**2)**0.5
  args.state.ballParents ||= []

  init_blocks args
  init_balls args
end

begin :default_methods
  def init_blocks args
    block_size = args.state.board_width / 8
    #Space inbetween each block
    block_offset = 4

    args.state.squares ||=[
      Square.new(args, 2, 0, block_size, :right, block_offset),
      Square.new(args, 5, 0, block_size, :right, block_offset),
      Square.new(args, 6, 7, block_size, :right, block_offset)
    ]


    #Possible orientations are :right, :left, :up, :down


    args.state.tshapes ||= [
      TShape.new(args, 0, 6, block_size, :left, block_offset),
      TShape.new(args, 3, 3, block_size, :down, block_offset),
      TShape.new(args, 0, 3, block_size, :right, block_offset),
      TShape.new(args, 0, 11, block_size, :up, block_offset)
    ]

    args.state.lines ||= [
      Line.new(args,3, 8, block_size, :down, block_offset),
      Line.new(args, 7, 3, block_size, :up, block_offset),
      Line.new(args, 3, 7, block_size, :right, block_offset)
    ]

    #exit()
  end

  def init_balls args
    return unless args.state.num_balls < BALL_COUNT


    #only create a new ball every 10 ticks
    return unless args.state.ball_created_at.elapsed_time > 10

    if (args.state.num_balls == 0)
      args.state.balls.append(Ball.new(args,args.state.num_balls,BALL_COUNT-1, nil, nil))
      args.state.ballParents = [args.state.balls[0]]
    else
      args.state.balls.append(Ball.new(args,args.state.num_balls,BALL_COUNT-1, args.state.balls.last, nil) )
      args.state.balls[-2].child = args.state.balls[-1]
    end
    args.state.ball_created_at = args.state.tick_count
    args.state.num_balls += 1
  end
end

#Render loop
def render args
  bgClr = {r:10, g:10, b:200}
  bgClr = {r:255-30, g:255-30, b:255-30}

  args.outputs.solids << [0, 0, $args.grid.right, $args.grid.top, bgClr[:r], bgClr[:g], bgClr[:b]];
  args.outputs.borders << args.state.game_area

  render_instructions args
  render_shapes args

  render_balls args

  #args.state.rectangle.draw args

  args.outputs.sprites << [$args.grid.right-(args.state.board_width + args.grid.w / 8), 0, $args.grid.right, $args.grid.top, "sprites/square-white-2.png", 0, 255, bgClr[:r], bgClr[:g], bgClr[:b]]
  args.outputs.sprites << [0, 0, (args.state.board_width + args.grid.w / 8), $args.grid.top, "sprites/square-white-2.png", 0, 255, bgClr[:r], bgClr[:g], bgClr[:b]]

end

begin :render_methods
  def render_instructions args
    #gtk.current_framerate
    args.outputs.labels << [20, $args.grid.top-20, "FPS: " + $gtk.current_framerate.to_s]
    if (args.state.balls != nil && args.state.balls[0] != nil)
        bx =  args.state.balls[0].velocity.x
        by =  args.state.balls[0].velocity.y
        bmg = (bx**2.0 + by**2.0)**0.5
        args.outputs.labels << [20, $args.grid.top-20-20, "V: " + bmg.to_s ]
    end


  end

  def render_shapes args
    for s in args.state.squares
      s.draw args
    end

    for l in args.state.lines
      l.draw args
    end

    for t in args.state.tshapes
      t.draw args
    end


  end

  def render_balls args
    #args.state.balls.each do |ball|
      #ball.draw args
    #end

    args.outputs.sprites << args.state.balls.map do |ball|
      ball.getDraw args
    end
  end
end

#Calls all methods necessary for performing calculations
def calc args
  for b in args.state.ballParents
    b.update args
  end

  for s in args.state.squares
    s.update args
  end

  for l in args.state.lines
    l.update args
  end

  for t in args.state.tshapes
    t.update args
  end



end

begin :calc_methods

end

def tick args
  defaults args
  render args
  calc args
end

    Arbitrary Collision - paddle.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/paddle.rb
class Paddle
  attr_accessor :enabled

  def initialize ()
    @x=WIDTH/2
    @y=100
    @width=100
    @height=20
    @speed=10

    @xyCollision  = LinearCollider.new({x: @x,y: @y+@height+5}, {x: @x+@width, y: @y+@height+5})
    @xyCollision2 = LinearCollider.new({x: @x,y: @y}, {x: @x+@width, y: @y}, :pos)
    @xyCollision3 = LinearCollider.new({x: @x,y: @y}, {x: @x, y: @y+@height+5})
    @xyCollision4 = LinearCollider.new({x: @x+@width,y: @y}, {x: @x+@width, y: @y+@height+5}, :pos)

    @enabled = true
  end

  def update args
    @xyCollision.resetPoints({x: @x,y: @y+@height+5}, {x: @x+@width, y: @y+@height+5})
    @xyCollision2.resetPoints({x: @x,y: @y}, {x: @x+@width, y: @y})
    @xyCollision3.resetPoints({x: @x,y: @y}, {x: @x, y: @y+@height+5})
    @xyCollision4.resetPoints({x: @x+@width,y: @y}, {x: @x+@width, y: @y+@height+5})

    @xyCollision.update  args
    @xyCollision2.update args
    @xyCollision3.update args
    @xyCollision4.update args

    args.inputs.keyboard.key_held.left  ||= false
    args.inputs.keyboard.key_held.right  ||= false

    if not (args.inputs.keyboard.key_held.left == args.inputs.keyboard.key_held.right)
      if args.inputs.keyboard.key_held.left && @enabled
        @x-=@speed
      elsif args.inputs.keyboard.key_held.right && @enabled
        @x+=@speed
      end
    end

    xmin =WIDTH/4
    xmax = 3*(WIDTH/4)
    @x = (@x+@width > xmax) ? xmax-@width : (@x<xmin) ? xmin : @x;
  end

  def render args
    args.outputs.solids << [@x,@y,@width,@height,255,0,0];
  end

  def rect
    [@x, @y, @width, @height]
  end
end

    Arbitrary Collision - rectangle.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/rectangle.rb
class Rectangle
  def initialize args

    @image = "sprites/roundSquare_white.png"
    @width  = 160.0
    @height = 80.0
    @x=$args.grid.right/2.0 - @width/2.0
    @y=$args.grid.top/2.0 - @height/2.0

    @xtmp = @width  * (1.0/10.0)
    @ytmp = @height * (1.0/10.0)

    #ball0 = args.state.balls[0]
    #hypotenuse = (args.state.balls[0].width**2 + args.state.balls[0].height**2)**0.5
    hypotenuse=args.state.ball_hypotenuse
    @boldXY = {x:(@x-hypotenuse/2)-1, y:(@y-hypotenuse/2)-1}
    @boldWidth = @width + hypotenuse + 2
    @boldHeight = @height + hypotenuse + 2
    @bold = [(@x-hypotenuse/2)-1,(@y-hypotenuse/2)-1,@width + hypotenuse + 2,@height + hypotenuse + 2]


    @points = [
      {x:@x,        y:@y+@ytmp},
      {x:@x+@xtmp,        y:@y},
      {x:@x+@width-@xtmp, y:@y},
      {x:@x+@width, y:@y+@ytmp},
      {x:@x+@width, y:@y+@height-@ytmp},#
      {x:@x+@width-@xtmp, y:@y+@height},
      {x:@x+@xtmp,        y:@y+@height},
      {x:@x,        y:@y+@height-@ytmp}
    ]

    @colliders = []
    #i = 0
    #while i < @points.length-1
      #@colliders.append(LinearCollider.new(@points[i],@points[i+1],:pos))
      #i+=1
    #end
    @colliders.append(LinearCollider.new(@points[0],@points[1], :neg))
    @colliders.append(LinearCollider.new(@points[1],@points[2], :neg))
    @colliders.append(LinearCollider.new(@points[2],@points[3], :neg))
    @colliders.append(LinearCollider.new(@points[3],@points[4], :neg))
    @colliders.append(LinearCollider.new(@points[4],@points[5], :pos))
    @colliders.append(LinearCollider.new(@points[5],@points[6], :pos))
    @colliders.append(LinearCollider.new(@points[6],@points[7], :pos))
    @colliders.append(LinearCollider.new(@points[0],@points[7], :pos))

  end

  def update args

    for b in args.state.balls
      if [b.x, b.y, b.width, b.height].intersect_rect?(@bold)
        for c in @colliders
          if c.collision?(args, b.getPoints(args),b)
            c.collide args, b
          end
        end
      end
    end
  end

  def draw args
    args.outputs.sprites << [
      @x,                                       # X
      @y,                                       # Y
      @width,                                   # W
      @height,                                  # H
      @image,                                   # PATH
      0,                                        # ANGLE
      255,                                      # ALPHA
      219,                                      # RED_SATURATION
      112,                                      # GREEN_SATURATION
      147                                       # BLUE_SATURATION
    ]
    #args.outputs.sprites << [@x, @y, @width, @height, "sprites/roundSquare_small_black.png"]
  end

  def serialize
  	{x: @x, y:@y}
  end

  def inspect
  	serialize.to_s
  end

  def to_s
  	serialize.to_s
  end
end

    Arbitrary Collision - square_collider.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/square_collider.rb

class SquareCollider
  def initialize x,y,direction,size=COLLISIONWIDTH
    @x = x
    @y = y
    @size = size
    @direction = direction

  end
  def collision? args, ball
    #args.outputs.solids <<  [@x, @y, @size, @size,     000, 255, 255]


    return [@x,@y,@size,@size].intersect_rect?([ball.x,ball.y,ball.width,ball.height])
  end

  def collide args, ball
    vmag = (ball.velocity.x**2.0 +ball.velocity.y**2.0)**0.5
    a = ((2.0**0.5)*vmag)/2.0
    if vmag < MAX_VELOCITY
      ball.velocity.x = (a) * @direction.x * 1.1
      ball.velocity.y = (a) * @direction.y * 1.1
    else
      ball.velocity.x = (a) * @direction.x
      ball.velocity.y = (a) * @direction.y
    end

  end
end

    Arbitrary Collision - vector2d.rb link

    # ./samples/04_physics_and_collisions/09_arbitrary_collision/app/vector2d.rb
class Vector2d
    attr_accessor :x, :y

    def initialize x=0, y=0
      @x=x
      @y=y
    end

    #returns a vector multiplied by scalar x
    #x [float] scalar
    def mult x
      r = Vector2d.new(0,0)
      r.x=@x*x
      r.y=@y*x
      r
    end

    # vect [Vector2d] vector to copy
    def copy vect
      Vector2d.new(@x, @y)
    end

    #returns a new vector equivalent to this+vect
    #vect [Vector2d] vector to add to self
    def add vect
      Vector2d.new(@x+vect.x,@y+vect.y)
    end

    #returns a new vector equivalent to this-vect
    #vect [Vector2d] vector to subtract to self
    def sub vect
      Vector2d.new(@x-vect.c, @y-vect.y)
    end

    #return the magnitude of the vector
    def mag
      ((@x**2)+(@y**2))**0.5
    end

    #returns a new normalize version of the vector
    def normalize
      Vector2d.new(@x/mag, @y/mag)
    end

    #TODO delet?
    def distABS vect
      (((vect.x-@x)**2+(vect.y-@y)**2)**0.5).abs()
    end
  end

    Collision With Object Removal - ball.rb link

    # ./samples/04_physics_and_collisions/10_collision_with_object_removal/app/ball.rb
class Ball
  #TODO limit accessors?
  attr_accessor :xy, :width, :height, :velocity


  #@xy [Vector2d] x,y position
  #@velocity [Vector2d] velocity of ball
  def initialize
    @xy = Vector2d.new(WIDTH/2,500)
    @velocity = Vector2d.new(4,-4)
    @width =  20
    @height = 20
  end

  #move the ball according to its velocity
  def update args
    @[email protected]
    @[email protected]
  end

  #render the ball to the screen
  def render args
    args.outputs.solids << [@xy.x,@xy.y,@width,@height,255,0,255];
    #args.outputs.labels << [20,HEIGHT-50,"velocity: " [email protected]_s+","[email protected]_s + "   magnitude:" + @velocity.mag.to_s]
  end

  def rect
    [@xy.x,@xy.y,@width,@height]
  end

end

    Collision With Object Removal - linear_collider.rb link

    # ./samples/04_physics_and_collisions/10_collision_with_object_removal/app/linear_collider.rb
#The LinearCollider (theoretically) produces collisions upon a line segment defined point.y two x,y cordinates

class LinearCollider

  #start [Array of length 2] start of the line segment as a x,y cordinate
  #last [Array of length 2] end of the line segment as a x,y cordinate

  #inorder for the LinearCollider to be functional the line segment must be said to have a thickness
  #(as it is unlikly that a colliding object will land exactly on the linesegment)

  #extension defines if the line's thickness extends negatively or positively
  #extension :pos     extends positively
  #extension :neg     extends negatively

  #thickness [float] how thick the line should be (should always be atleast as large as the magnitude of the colliding object)
  def initialize (pointA, pointB, extension=:neg, thickness=10)
    @pointA = pointA
    @pointB = pointB
    @thickness = thickness
    @extension = extension

    @pointAExtended={
      x: @pointA.x + @thickness*(@extension == :neg ? -1 : 1),
      y: @pointA.y + @thickness*(@extension == :neg ? -1 : 1)
    }
    @pointBExtended={
      x: @pointB.x + @thickness*(@extension == :neg ? -1 : 1),
      y: @pointB.y + @thickness*(@extension == :neg ? -1 : 1)
    }

  end

  def resetPoints(pointA,pointB)
    @pointA = pointA
    @pointB = pointB

    @pointAExtended={
      x:@pointA.x + @thickness*(@extension == :neg ? -1 : 1),
      y:@pointA.y + @thickness*(@extension == :neg ? -1 : 1)
    }
    @pointBExtended={
      x:@pointB.x + @thickness*(@extension == :neg ? -1 : 1),
      y:@pointB.y + @thickness*(@extension == :neg ? -1 : 1)
    }
  end

  #TODO: Ugly function
  def slope (pointA, pointB)
    return (pointB.x==pointA.x) ? INFINITY : (pointB.y+-pointA.y)/(pointB.x+-pointA.x)
  end

  #TODO: Ugly function
  def intercept(pointA, pointB)
    if (slope(pointA, pointB) == INFINITY)
      -INFINITY
    elsif slope(pointA, pointB) == -1*INFINITY
      INFINITY
    else
      pointA.y+-1.0*(slope(pointA, pointB)*pointA.x)
    end
  end

  def calcY(pointA, pointB, x)
    return slope(pointA, pointB)*x + intercept(pointA, pointB)
  end

  #test if a collision has occurred
  def isCollision? (point)
    #INFINITY slop breaks down when trying to determin collision, ergo it requires a special test
    if slope(@pointA, @pointB) ==  INFINITY &&
      point.x >= [@pointA.x,@pointB.x].min+(@extension == :pos ? -@thickness : 0) &&
      point.x <= [@pointA.x,@pointB.x].max+(@extension == :neg ?  @thickness : 0) &&
      point.y >= [@pointA.y,@pointB.y].min && point.y <= [@pointA.y,@pointB.y].max
        return true
    end

    isNegInLine   = @extension == :neg &&
                    point.y <= slope(@pointA, @pointB)*point.x+intercept(@pointA,@pointB) &&
                    point.y >= point.x*slope(@pointAExtended, @pointBExtended)+intercept(@pointAExtended,@pointBExtended)
    isPosInLine   = @extension == :pos &&
                    point.y >= slope(@pointA, @pointB)*point.x+intercept(@pointA,@pointB) &&
                    point.y <= point.x*slope(@pointAExtended, @pointBExtended)+intercept(@pointAExtended,@pointBExtended)
    isInBoxBounds = point.x >= [@pointA.x,@pointB.x].min &&
                    point.x <= [@pointA.x,@pointB.x].max &&
                    point.y >= [@pointA.y,@pointB.y].min+(@extension == :neg ? -@thickness : 0) &&
                    point.y <= [@pointA.y,@pointB.y].max+(@extension == :pos ? @thickness : 0)

    return isInBoxBounds && (isNegInLine || isPosInLine)

  end

  def getRepelMagnitude (fbx, fby, vrx, vry, args)
    a = fbx ; b = vrx ; c = fby
    d = vry ; e = args.state.ball.velocity.mag

    if b**2 + d**2 == 0
      puts "magnitude error"
    end

    x1 = (-a*b+-c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 + d**2 - a**2 * d**2)**0.5)/(b**2 + d**2)
    x2 = -((a*b + c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 * d**2 - a**2 * d**2)**0.5)/(b**2 + d**2))
    return ((a+x1*b)**2 + (c+x1*d)**2 == e**2) ? x1 : x2
  end

  def update args
    #each of the four points on the square ball - NOTE simple to extend to a circle
    points= [ {x: args.state.ball.xy.x,                          y: args.state.ball.xy.y},
              {x: args.state.ball.xy.x+args.state.ball.width,    y: args.state.ball.xy.y},
              {x: args.state.ball.xy.x,                          y: args.state.ball.xy.y+args.state.ball.height},
              {x: args.state.ball.xy.x+args.state.ball.width,    y: args.state.ball.xy.y + args.state.ball.height}
            ]

    #for each point p in points
    for point in points
      #isCollision.md has more information on this section
      #TODO: section can certainly be simplifyed
      if isCollision?(point)
        u = Vector2d.new(1.0,((slope(@pointA, @pointB)==0) ? INFINITY : -1/slope(@pointA, @pointB))*1.0).normalize #normal perpendicular (to line segment) vector

        #the vector with the repeling force can be u or -u depending of where the ball was coming from in relation to the line segment
        previousBallPosition=Vector2d.new(point.x-args.state.ball.velocity.x,point.y-args.state.ball.velocity.y)
        choiceA = (u.mult(1))
        choiceB =  (u.mult(-1))
        vectorRepel = nil

        if (slope(@pointA, @pointB))!=INFINITY && u.y < 0
          choiceA, choiceB = choiceB, choiceA
        end
        vectorRepel = (previousBallPosition.y > calcY(@pointA, @pointB, previousBallPosition.x)) ? choiceA : choiceB

        #vectorRepel = (previousBallPosition.y > slope(@pointA, @pointB)*previousBallPosition.x+intercept(@pointA,@pointB)) ? choiceA : choiceB)
        if (slope(@pointA, @pointB) == INFINITY) #slope INFINITY breaks down in the above test, ergo it requires a custom test
          vectorRepel = (previousBallPosition.x > @pointA.x) ? (u.mult(1)) : (u.mult(-1))
        end
        #puts ("     " + $t[0].to_s + "," + $t[1].to_s + "    " + $t[2].to_s + "," + $t[3].to_s + "     " + "   " + u.x.to_s + "," + u.y.to_s)
        #vectorRepel now has the repeling force

        mag = args.state.ball.velocity.mag
        theta_ball=Math.atan2(args.state.ball.velocity.y,args.state.ball.velocity.x) #the angle of the ball's velocity
        theta_repel=Math.atan2(vectorRepel.y,vectorRepel.x) #the angle of the repeling force
        #puts ("theta:" + theta_ball.to_s + " " + theta_repel.to_s) #theta okay

        fbx = mag * Math.cos(theta_ball) #the x component of the ball's velocity
        fby = mag * Math.sin(theta_ball) #the y component of the ball's velocity

        repelMag = getRepelMagnitude(fbx, fby, vectorRepel.x, vectorRepel.y, args)

        frx = repelMag* Math.cos(theta_repel) #the x component of the repel's velocity | magnitude is set to twice of fbx
        fry = repelMag* Math.sin(theta_repel) #the y component of the repel's velocity | magnitude is set to twice of fby

        fsumx = fbx+frx #sum of x forces
        fsumy = fby+fry #sum of y forces
        fr = mag#fr is the resulting magnitude
        thetaNew = Math.atan2(fsumy, fsumx)  #thetaNew is the resulting angle
        xnew = fr*Math.cos(thetaNew) #resulting x velocity
        ynew = fr*Math.sin(thetaNew) #resulting y velocity

        args.state.ball.velocity = Vector2d.new(xnew,ynew)
        #args.state.ball.xy.add(args.state.ball.velocity)
        break #no need to check the other points ?
      else
      end
    end
  end #end update

end

    Collision With Object Removal - main.rb link

    # ./samples/04_physics_and_collisions/10_collision_with_object_removal/app/main.rb
# coding: utf-8
INFINITY= 10**10
WIDTH=1280
HEIGHT=720

require 'app/vector2d.rb'
require 'app/paddle.rb'
require 'app/ball.rb'
require 'app/linear_collider.rb'

#Method to init default values
def defaults args
  args.state.game_board ||= [(args.grid.w / 2 - args.grid.w / 4), 0, (args.grid.w / 2), args.grid.h]
  args.state.bricks ||= []
  args.state.num_bricks ||= 0
  args.state.game_over_at ||= 0
  args.state.paddle ||= Paddle.new
  args.state.ball   ||= Ball.new
  args.state.westWall  ||= LinearCollider.new({x: args.grid.w/4,      y: 0},          {x: args.grid.w/4,      y: args.grid.h}, :pos)
  args.state.eastWall  ||= LinearCollider.new({x: 3*args.grid.w*0.25, y: 0},          {x: 3*args.grid.w*0.25, y: args.grid.h})
  args.state.southWall ||= LinearCollider.new({x: 0,                  y: 0},          {x: args.grid.w,        y: 0})
  args.state.northWall ||= LinearCollider.new({x: 0,                  y:args.grid.h}, {x: args.grid.w,        y: args.grid.h}, :pos)

  #args.state.testWall ||= LinearCollider.new({x:0 , y:0},{x:args.grid.w, y:args.grid.h})
end

#Render loop
def render args
  render_instructions args
  render_board args
  render_bricks args
end

begin :render_methods
  #Method to display the instructions of the game
  def render_instructions args
    args.outputs.labels << [225, args.grid.h - 30, "← and → to move the paddle left and right",  0, 1]
  end

  def render_board args
    args.outputs.borders << args.state.game_board
  end

  def render_bricks args
    args.outputs.solids << args.state.bricks.map(&:rect)
  end
end

#Calls all methods necessary for performing calculations
def calc args
  add_new_bricks args
  reset_game args
  calc_collision args
  win_game args

  args.state.westWall.update args
  args.state.eastWall.update args
  args.state.southWall.update args
  args.state.northWall.update args
  args.state.paddle.update args
  args.state.ball.update args

  #args.state.testWall.update args

  args.state.paddle.render args
  args.state.ball.render args
end

begin :calc_methods
  def add_new_bricks args
    return if args.state.num_bricks > 40

    #Width of the game board is 640px
    brick_width = (args.grid.w / 2) / 10
    brick_height = brick_width / 2

    (4).map_with_index do |y|
      #Make a box that is 10 bricks wide and 4 bricks tall
      args.state.bricks += (10).map_with_index do |x|
        args.state.new_entity(:brick) do |b|
          b.x = x * brick_width + (args.grid.w / 2 - args.grid.w / 4)
          b.y = args.grid.h - ((y + 1) * brick_height)
          b.rect = [b.x + 1, b.y - 1, brick_width - 2, brick_height - 2, 235, 50 * y, 52]

          #Add linear colliders to the brick
          b.collider_bottom = LinearCollider.new([(b.x-2), (b.y-5)], [(b.x+brick_width+1), (b.y-5)], :pos, brick_height)
          b.collider_right = LinearCollider.new([(b.x+brick_width+1), (b.y-5)], [(b.x+brick_width+1), (b.y+brick_height+1)], :pos)
          b.collider_left = LinearCollider.new([(b.x-2), (b.y-5)], [(b.x-2), (b.y+brick_height+1)], :neg)
          b.collider_top = LinearCollider.new([(b.x-2), (b.y+brick_height+1)], [(b.x+brick_width+1), (b.y+brick_height+1)], :neg)

          # @xyCollision  = LinearCollider.new({x: @x,y: @y+@height}, {x: @x+@width, y: @y+@height})
          # @xyCollision2 = LinearCollider.new({x: @x,y: @y}, {x: @x+@width, y: @y}, :pos)
          # @xyCollision3 = LinearCollider.new({x: @x,y: @y}, {x: @x, y: @y+@height})
          # @xyCollision4 = LinearCollider.new({x: @x+@width,y: @y}, {x: @x+@width, y: @y+@height}, :pos)

          b.broken = false

          args.state.num_bricks += 1
        end
      end
    end
  end

  def reset_game args
    if args.state.ball.xy.y < 20 && args.state.game_over_at.elapsed_time > 60
      #Freeze the ball
      args.state.ball.velocity.x = 0
      args.state.ball.velocity.y = 0
      #Freeze the paddle
      args.state.paddle.enabled = false

      args.state.game_over_at = args.state.tick_count
    end

    if args.state.game_over_at.elapsed_time < 60 && args.state.tick_count > 60 && args.state.bricks.count != 0
      #Display a "Game over" message
      args.outputs.labels << [100, 100, "GAME OVER", 10]
    end

    #If 60 frames have passed since the game ended, restart the game
    if args.state.game_over_at != 0 && args.state.game_over_at.elapsed_time == 60
      # FIXME: only put value types in state
      args.state.ball = Ball.new

      # FIXME: only put value types in state
      args.state.paddle = Paddle.new

      args.state.bricks = []
      args.state.num_bricks = 0
    end
  end

  def calc_collision args
    #Remove the brick if it is hit with the ball
    ball = args.state.ball
    ball_rect = [ball.xy.x, ball.xy.y, 20, 20]

    #Loop through each brick to see if the ball is colliding with it
    args.state.bricks.each do |b|
      if b.rect.intersect_rect?(ball_rect)
        #Run the linear collider for the brick if there is a collision
        b[:collider_bottom].update args
        b[:collider_right].update args
        b[:collider_left].update args
        b[:collider_top].update args

        b.broken = true
      end
    end

    args.state.bricks = args.state.bricks.reject(&:broken)
  end

  def win_game args
    if args.state.bricks.count == 0 && args.state.game_over_at.elapsed_time > 60
      #Freeze the ball
      args.state.ball.velocity.x = 0
      args.state.ball.velocity.y = 0
      #Freeze the paddle
      args.state.paddle.enabled = false

      args.state.game_over_at = args.state.tick_count
    end

    if args.state.game_over_at.elapsed_time < 60 && args.state.tick_count > 60 && args.state.bricks.count == 0
      #Display a "Game over" message
      args.outputs.labels << [100, 100, "CONGRATULATIONS!", 10]
    end
  end

end

def tick args
  defaults args
  render args
  calc args

  #args.outputs.lines << [0, 0, args.grid.w, args.grid.h]

  #$tc+=1
  #if $tc == 5
    #$train << [args.state.ball.xy.x, args.state.ball.xy.y]
    #$tc = 0
  #end
  #for t in $train

    #args.outputs.solids << [t[0],t[1],5,5,255,0,0];
  #end
end

    Collision With Object Removal - paddle.rb link

    # ./samples/04_physics_and_collisions/10_collision_with_object_removal/app/paddle.rb
class Paddle
  attr_accessor :enabled

  def initialize ()
    @x=WIDTH/2
    @y=100
    @width=100
    @height=20
    @speed=10

    @xyCollision  = LinearCollider.new({x: @x,y: @y+@height+5}, {x: @x+@width, y: @y+@height+5})
    @xyCollision2 = LinearCollider.new({x: @x,y: @y}, {x: @x+@width, y: @y}, :pos)
    @xyCollision3 = LinearCollider.new({x: @x,y: @y}, {x: @x, y: @y+@height+5})
    @xyCollision4 = LinearCollider.new({x: @x+@width,y: @y}, {x: @x+@width, y: @y+@height+5}, :pos)

    @enabled = true
  end

  def update args
    @xyCollision.resetPoints({x: @x,y: @y+@height+5}, {x: @x+@width, y: @y+@height+5})
    @xyCollision2.resetPoints({x: @x,y: @y}, {x: @x+@width, y: @y})
    @xyCollision3.resetPoints({x: @x,y: @y}, {x: @x, y: @y+@height+5})
    @xyCollision4.resetPoints({x: @x+@width,y: @y}, {x: @x+@width, y: @y+@height+5})

    @xyCollision.update  args
    @xyCollision2.update args
    @xyCollision3.update args
    @xyCollision4.update args

    args.inputs.keyboard.key_held.left  ||= false
    args.inputs.keyboard.key_held.right  ||= false

    if not (args.inputs.keyboard.key_held.left == args.inputs.keyboard.key_held.right)
      if args.inputs.keyboard.key_held.left && @enabled
        @x-=@speed
      elsif args.inputs.keyboard.key_held.right && @enabled
        @x+=@speed
      end
    end

    xmin =WIDTH/4
    xmax = 3*(WIDTH/4)
    @x = (@x+@width > xmax) ? xmax-@width : (@x<xmin) ? xmin : @x;
  end

  def render args
    args.outputs.solids << [@x,@y,@width,@height,255,0,0];
  end

  def rect
    [@x, @y, @width, @height]
  end
end

    Collision With Object Removal - tests.rb link

    # ./samples/04_physics_and_collisions/10_collision_with_object_removal/app/tests.rb
# For advanced users:
# You can put some quick verification tests here, any method
# that starts with the `test_` will be run when you save this file.

# Here is an example test and game

# To run the test: ./dragonruby mygame --eval app/tests.rb --no-tick

class MySuperHappyFunGame
  attr_gtk

  def tick
    outputs.solids << [100, 100, 300, 300]
  end
end

def test_universe args, assert
  game = MySuperHappyFunGame.new
  game.args = args
  game.tick
  assert.true!  args.outputs.solids.length == 1, "failure: a solid was not added after tick"
  assert.false! 1 == 2, "failure: some how, 1 equals 2, the world is ending"
  puts "test_universe completed successfully"
end

puts "running tests"
$gtk.reset 100
$gtk.log_level = :off
$gtk.tests.start

    Collision With Object Removal - vector2d.rb link

    # ./samples/04_physics_and_collisions/10_collision_with_object_removal/app/vector2d.rb

class Vector2d
  attr_accessor :x, :y

  def initialize x=0, y=0
    @x=x
    @y=y
  end

  #returns a vector multiplied by scalar x
  #x [float] scalar
  def mult x
    r = Vector2d.new(0,0)
    r.x=@x*x
    r.y=@y*x
    r
  end

  # vect [Vector2d] vector to copy
  def copy vect
    Vector2d.new(@x, @y)
  end

  #returns a new vector equivalent to this+vect
  #vect [Vector2d] vector to add to self
  def add vect
    Vector2d.new(@x+vect.x,@y+vect.y)
  end

  #returns a new vector equivalent to this-vect
  #vect [Vector2d] vector to subtract to self
  def sub vect
    Vector2d.new(@x-vect.c, @y-vect.y)
  end

  #return the magnitude of the vector
  def mag
    ((@x**2)+(@y**2))**0.5
  end

  #returns a new normalize version of the vector
  def normalize
    Vector2d.new(@x/mag, @y/mag)
  end

  #TODO delet?
  def distABS vect
    (((vect.x-@x)**2+(vect.y-@y)**2)**0.5).abs()
  end
end

    Bouncing Ball With Gravity - main.rb link

    # ./samples/04_physics_and_collisions/11_bouncing_ball_with_gravity/app/main.rb
class Game
  attr_gtk

  def tick
    outputs.labels << { x: 30, y: 30.from_top,
                        text: "left/right arrow keys to spin, up arrow to jump, ctrl+r to reset, click two points to place terrain" }
    defaults
    calc
    render
  end

  def defaults
    state.terrain ||= []

    state.player ||= { x: 100,
                       y: 640,
                       dx: 0,
                       dy: 0,
                       radius: 12,
                       drag: 0.05477,
                       gravity: 0.03,
                       entropy: 0.9,
                       angle: 0,
                       facing: 1,
                       angle_velocity: 0,
                       elasticity: 0.5 }

    state.grid_points ||= (1280.idiv(40) + 1).flat_map do |x|
      (720.idiv(40) + 1).map do |y|
        { x: x * 40,
          y: y * 40,
          w: 40,
          h: 40,
          anchor_x: 0.5,
          anchor_y: 0.5 }
      end
    end
  end

  def calc
    player.y = 720  if player.y < 0
    player.x = 1280 if player.x < 0
    player.x = 0    if player.x > 1280
    player.angle_velocity = player.angle_velocity.clamp(-30, 30)
    calc_edit_mode
    calc_play_mode
  end

  def calc_edit_mode
    state.current_grid_point = geometry.find_intersect_rect(inputs.mouse, state.grid_points)
    calc_edit_mode_click
  end

  def calc_edit_mode_click
    return if !state.current_grid_point
    return if !inputs.mouse.click

    if !state.start_point
      state.start_point = state.current_grid_point
    else
      state.terrain << { x: state.start_point.x,
                         y: state.start_point.y,
                         x2: state.current_grid_point.x,
                         y2: state.current_grid_point.y }
      state.start_point = nil
    end
  end

  def calc_play_mode
    player.x += player.dx
    player.dy -= player.gravity
    player.y += player.dy
    player.angle += player.angle_velocity
    player.dy += player.dy * player.drag ** 2 * -1
    player.dx += player.dx * player.drag ** 2 * -1
    player.colliding = false
    player.colliding_with = nil

    if inputs.keyboard.key_down.up
      player.dy += 5 * player.angle.vector_y
      player.dx += 5 * player.angle.vector_x
    end
    player.angle_velocity += inputs.left_right * -1
    player.facing = if inputs.left_right == -1
                      -1
                    elsif inputs.left_right == 1
                      1
                    else
                      player.facing
                    end

    collisions = player_terrain_collisions
    collisions.each do |collision|
      collide! player, collision
    end

    if player.colliding_with
      roll! player, player.colliding_with
    end
  end

  def reflect_velocity! circle, line
    slope = geometry.line_slope line, replace_infinity: 1000
    slope_angle = geometry.line_angle line
    if slope_angle == 90 || slope_angle == 270
      circle.dx *= -circle.elasticity
    else
      circle.angle_velocity += slope * (circle.dx.abs + circle.dy.abs)
      vec = line.x2 - line.x, line.y2 - line.y
      len = Math.sqrt(vec.x**2 + vec.y**2)

      vec.x /= len
      vec.y /= len

      n = geometry.vec2_normal vec

      v_dot_n = geometry.vec2_dot_product({ x: circle.dx, y: circle.dy }, n)

      circle.dx = circle.dx - n.x * (2 * v_dot_n)
      circle.dy = circle.dy - n.y * (2 * v_dot_n)
      circle.dx *= circle.elasticity
      circle.dy *= circle.elasticity
      half_terminal_velocity = 10
      impact_intensity = (circle.dy.abs) / half_terminal_velocity
      impact_intensity = 1 if impact_intensity > 1

      final = (0.9 - 0.8 * impact_intensity)
      next_angular_velocity = circle.angle_velocity * final
      circle.angle_velocity *= final

      if (circle.dx.abs + circle.dy.abs) <= 0.2
        circle.dx = 0
        circle.dy = 0
        circle.angle_velocity *= 0.99
      end

      if circle.angle_velocity.abs <= 0.1
        circle.angle_velocity = 0
      end
    end
  end

  def position_on_line! circle, line
    circle.colliding = true
    point = geometry.line_normal line, circle
    if point.y > circle.y
      circle.colliding_from_above = true
    else
      circle.colliding_from_above = false
    end

    circle.colliding_with = line

    if !geometry.point_on_line? point, line
      distance_from_start_of_line = geometry.distance_squared({ x: line.x, y: line.y }, point)
      distance_from_end_of_line = geometry.distance_squared({ x: line.x2, y: line.y2 }, point)
      if distance_from_start_of_line < distance_from_end_of_line
        point = { x: line.x, y: line.y }
      else
        point = { x: line.x2, y: line.y2 }
      end
    end
    angle = geometry.angle_to point, circle
    circle.y = point.y + angle.vector_y * (circle.radius)
    circle.x = point.x + angle.vector_x * (circle.radius)
  end

  def collide! circle, line
    return if !line
    position_on_line! circle, line
    reflect_velocity! circle, line
    next_player = { x: player.x + player.dx,
                    y: player.y + player.dy,
                    radius: player.radius }
  end

  def roll! circle, line
    slope_angle = geometry.line_angle line
    return if slope_angle == 90 || slope_angle == 270

    ax = -circle.gravity * slope_angle.vector_y
    ay = -circle.gravity * slope_angle.vector_x

    if ax.abs < 0.05 && ay.abs < 0.05
      ax = 0
      ay = 0
    end

    friction_coefficient = 0.0001
    friction_force = friction_coefficient * circle.gravity * slope_angle.vector_x

    circle.dy += ay
    circle.dx += ax

    if circle.colliding_from_above
      circle.dx += circle.angle_velocity * slope_angle.vector_x * 0.1
      circle.dy += circle.angle_velocity * slope_angle.vector_y * 0.1
    else
      circle.dx += circle.angle_velocity * slope_angle.vector_x * -0.1
      circle.dy += circle.angle_velocity * slope_angle.vector_y * -0.1
    end

    if circle.dx != 0
      circle.dx -= friction_force * (circle.dx / circle.dx.abs)
    end

    if circle.dy != 0
      circle.dy -= friction_force * (circle.dy / circle.dy.abs)
    end
  end

  def player_terrain_collisions
    terrain.find_all do |terrain|
             geometry.circle_intersect_line? player, terrain
           end
           .sort_by do |terrain|
             if player.facing == -1
               -terrain.x
             else
               terrain.x
             end
           end
  end

  def render
    render_current_grid_point
    render_preview_line
    render_grid_points
    render_terrain
    render_player
    render_player_terrain_collisions
  end

  def render_player_terrain_collisions
    collisions = player_terrain_collisions
    outputs.lines << collisions.map do |collision|
                       { x: collision.x,
                         y: collision.y,
                         x2: collision.x2,
                         y2: collision.y2,
                         r: 255,
                         g: 0,
                         b: 0 }
                     end
  end

  def render_current_grid_point
    return if state.game_mode == :play
    return if !state.current_grid_point
    outputs.sprites << state.current_grid_point
                            .merge(w: 8,
                                   h: 8,
                                   anchor_x: 0.5,
                                   anchor_y: 0.5,
                                   path: :solid,
                                   g: 0,
                                   r: 0,
                                   b: 0,
                                   a: 128)
  end

  def render_preview_line
    return if state.game_mode == :play
    return if !state.start_point
    return if !state.current_grid_point

    outputs.lines << { x: state.start_point.x,
                       y: state.start_point.y,
                       x2: state.current_grid_point.x,
                       y2: state.current_grid_point.y }
  end

  def render_grid_points
    outputs
      .sprites << state
                    .grid_points
                    .map do |point|
      point.merge w: 8,
                  h: 8,
                  anchor_x: 0.5,
                  anchor_y: 0.5,
                  path: :solid,
                  g: 255,
                  r: 255,
                  b: 255,
                  a: 128
    end
  end

  def render_terrain
    outputs.lines << state.terrain
  end

  def render_player
    outputs.sprites << player_prefab
  end

  def player_prefab
    flip_horizontally = player.facing == -1
    { x: player.x,
      y: player.y,
      w: player.radius * 2,
      h: player.radius * 2,
      angle: player.angle,
      anchor_x: 0.5,
      anchor_y: 0.5,
      path: "sprites/circle/blue.png" }
  end

  def player
    state.player
  end

  def terrain
    state.terrain
  end
end

def tick args
  $game ||= Game.new
  $game.args = args
  $game.tick
end

def reset args
  $terrain = args.state.terrain
  $game = nil
end

    Ramp Collision - main.rb link

    # ./samples/04_physics_and_collisions/12_ramp_collision/app/main.rb
# sample app shows how to do ramp collision
# based off of the writeup here:
# http://higherorderfun.com/blog/2012/05/20/the-guide-to-implementing-2d-platformers/

# NOTE: at the bottom of the file you'll find $gtk.reset_and_replay "replay.txt"
#       whenever you make changes to this file, a replay will automatically run so you can
#       see how your changes affected the game. Comment out the line at the bottom if you
#       don't want the replay to autmatically run.

# toolbar interaction is in a seperate file
require 'app/toolbar.rb'

def tick args
  tick_toolbar args
  tick_game args
end

def tick_game args
  game_defaults args
  game_input args
  game_calc args
  game_render args
end

def game_input args
  # if space is pressed or held (signifying a jump)
  if args.inputs.keyboard.space
    # change the player's dy to the jump power if the
    # player is not currently touching a ceiling
    if !args.state.player.on_ceiling
      args.state.player.dy = args.state.player.jump_power
      args.state.player.on_floor = false
      args.state.player.jumping = true
    end
  else
    # if the space key is released, then jumping is false
    # and the player will no longer be on the ceiling
    args.state.player.jumping = false
    args.state.player.on_ceiling = false
  end

  # set the player's dx value to the left/right input
  # NOTE: that the speed of the player's dx movement has
  #       a sensitive relation ship with collision detection.
  #       If you increase the speed of the player, you may
  #       need to tweak the collision code to compensate for
  #       the extra horizontal speed.
  args.state.player.dx = args.inputs.left_right * 2
end

def game_render args
  # for each terrain entry, render the line that represents the connection
  # from the tile's left_height to the tile's right_height
  args.outputs.primitives << args.state.terrain.map { |t| t.line }

  # determine if the player sprite needs to be flipped hoizontally
  flip_horizontally = args.state.player.facing == -1

  # render the player
  args.outputs.sprites << args.state.player.merge(flip_horizontally: flip_horizontally)

  args.outputs.labels << {
    x: 640,
    y: 100,
    alignment_enum: 1,
    text: "Left and Right to move player. Space to jump. Use the toolbar at the top to add more terrain."
  }

  args.outputs.labels << {
    x: 640,
    y: 60,
    alignment_enum: 1,
    text: "Click any existing terrain on the map to delete it."
  }
end

def game_calc args
  # set the direction the player is facing based on the
  # the dx value of the player
  if args.state.player.dx > 0
    args.state.player.facing = 1
  elsif args.state.player.dx < 0
    args.state.player.facing = -1
  end

  # preform the calcuation of ramp collision
  calc_collision args

  # reset the player if the go off screen
  calc_off_screen args
end

def game_defaults args
  # how much gravity is in the game
  args.state.gravity ||= 0.1

  # initialized the player to the center of the screen
  args.state.player ||= {
    x: 640,
    y: 360,
    w: 16,
    h: 16,
    dx: 0,
    dy: 0,
    jump_power: 3,
    path: 'sprites/square/blue.png',
    on_floor: false,
    on_ceiling: false,
    facing: 1
  }
end

def calc_collision args
  # increment the players x position by the dx value
  args.state.player.x += args.state.player.dx

  # if the player is not on the floor
  if !args.state.player.on_floor
    # then apply gravity
    args.state.player.dy -= args.state.gravity
    # clamp the max dy value to -12 to 12
    args.state.player.dy = args.state.player.dy.clamp(-12, 12)

    # update the player's y position by the dy value
    args.state.player.y += args.state.player.dy
  end

  # get all colisions between the player and the terrain
  collisions = args.state.geometry.find_all_intersect_rect args.state.player, args.state.terrain

  # if there are no collisions, then the player is not on the floor or ceiling
  # return from the method since there is nothing more to process
  if collisions.length == 0
    args.state.player.on_floor = false
    args.state.player.on_ceiling = false
    return
  end

  # set a local variable to the player since
  # we'll be accessing it a lot
  player = args.state.player

  # sort the collisions by the distance from the collision's center to the player's center
  sorted_collisions = collisions.sort_by do |collision|
    player_center = player.x + player.w / 2
    collision_center = collision.x + collision.w / 2
    (player_center - collision_center).abs
  end

  # define a one pixel wide rectangle that represents the center of the player
  # we'll use this value to determine the location of the player's feet on
  # a ramp
  player_center_rect = {
    x: player.x + player.w / 2 - 0.5,
    y: player.y,
    w: 1,
    h: player.h
  }

  # for each collision...
  sorted_collisions.each do |collision|
    # if the player doesn't intersect with the collision,
    # then set the player's on_floor and on_ceiling values to false
    # and continue to the next collision
    if !collision.intersect_rect? player_center_rect
      player.on_floor = false
      player.on_ceiling = false
      next
    end

    if player.dy < 0
      # if the player is falling
      # the percentage of the player's center relative to the collision
      # is a difference from the collision to the player (as opposed to the player to the collision)
      perc = (collision.x - player_center_rect.x) / player.w
      height_of_slope = collision.tile.left_height - collision.tile.right_height

      new_y = (collision.y + collision.tile.left_height + height_of_slope * perc)
      diff = new_y - player.y

      if diff < 0
        # if the current fall rate of the player is less than the difference
        # of the player's new y position and the player's current y position
        # then don't set the player's y position to the new y position
        # and wait for another application of gravity to bring the player a little
        # closer
        if player.dy.abs >= diff.abs
          # if the player's current fall speed can cover the distance to the
          # new y position, then set the player's y position to the new y position
          # and mark them as being on the floor so that gravity no longer get's processed
          player.y = new_y
          player.on_floor = true

          # given the player's speed, set the player's dy to a value that will
          # keep them from bouncing off the floor when the ramp is steep
          # NOTE: if you change the player's speed, then this value will need to be adjusted
          #       to keep the player from bouncing off the floor
          player.dy = -1
        end
      elsif diff > 0 && diff < 8
        # there's a small edge case where collision may be processed from
        # below the terrain (eg when the player is jumping up and hitting the
        # ramp from below). The moment when jump is released, the player's dy
        # value could result in the player tunneling through the terrain,
        # and get popped on to the top side.

        # testing to make sure the distance that will be displaced is less than
        # 8 pixels will keep this tunneling from happening
        player.y = new_y
        player.on_floor = true

        # given the player's speed, set the player's dy to a value that will
        # keep them from bouncing off the floor when the ramp is steep
        # NOTE: if you change the player's speed, then this value will need to be adjusted
        #       to keep the player from bouncing off the floor
        player.dy = -1
      end
    elsif player.dy > 0
      # if the player is jumping
      # the percentage of the player's center relative to the collision
      # is a difference is reversed from the player to the collision (as opposed to the player to the collision)
      perc = (player_center_rect.x - collision.x) / player.w

      # the height of the slope is also reversed when approaching the collision from the bottom
      height_of_slope = collision.tile.right_height - collision.tile.left_height

      new_y = collision.y + collision.tile.left_height + height_of_slope * perc

      # since this collision is being processed from below, the difference
      # between the current players position and the new y position is
      # based off of the player's top position (their head)
      player_top = player.y + player.h

      diff = new_y - player_top

      # we also need to calculate the difference between the player's bottom
      # and the new position. This will be used to determine if the player
      # can jump from the new_y position
      diff_bottom = new_y - player.y


      # if the player's current rising speed can cover the distance to the
      # new y position, then set the player's y position to the new y position
      # an mark them as being on the floor so that gravity no longer get's processed
      can_cover_distance_to_new_y = player.dy >= diff.abs && player.dy.sign == diff.sign

      # another scenario that needs to be covered is if the player's top is already passed
      # the new_y position (their rising speed made them partially clip through the collision)
      player_top_above_new_y = player_top > new_y

      # if either of the conditions above is true then we want to set the player's y position
      if can_cover_distance_to_new_y || player_top_above_new_y
        # only set the player's y position to the new y position if the player's
        # cannot escape the collision by jumping up from the new_y position
        if diff_bottom >= player.jump_power
          player.y = new_y.floor - player.h

          # after setting the new_y position, we need to determine if the player
          # if the player is touching the ceiling or not
          # touching the ceiling disables the ability for the player to jump/increase
          # their dy value any more than it already is
          if player.jumping
            # disable jumping if the player is currently moving upwards
            player.on_ceiling = true

            # NOTE: if you change the player's speed, then this value will need to be adjusted
            #       to keep the player from bouncing off the ceiling as they move right and left
            player.dy = 1
          else
            # if the player is not currently jumping, then set their dy to 0
            # so they can immediately start falling after the collision
            # this also means that they are no longer on the ceiling and can jump again
            player.dy = 0
            player.on_ceiling = false
          end
        end
      end
    end
  end
end

def calc_off_screen args
  below_screen = args.state.player.y + args.state.player.h < 0
  above_screen = args.state.player.y > 720 + args.state.player.h
  off_screen_left = args.state.player.x + args.state.player.w < 0
  off_screen_right = args.state.player.x > 1280

  # if the player is off the screen, then reset them to the top of the screen
  if below_screen || above_screen || off_screen_left || off_screen_right
    args.state.player.x = 640
    args.state.player.y = 720
    args.state.player.dy = 0
    args.state.player.on_floor = false
  end
end

$gtk.reset_and_replay "replay.txt", speed: 2

    Ramp Collision - toolbar.rb link

    # ./samples/04_physics_and_collisions/12_ramp_collision/app/toolbar.rb
def tick_toolbar args
  # ================================================
  # tollbar defaults
  # ================================================
  if !args.state.toolbar
    # these are the tiles you can select from
    tile_definitions = [
      { name: "16-12", left_height: 16, right_height: 12  },
      { name: "12-8",  left_height: 12, right_height: 8   },
      { name: "8-4",   left_height: 8,  right_height: 4   },
      { name: "4-0",   left_height: 4,  right_height: 0   },
      { name: "0-4",   left_height: 0,  right_height: 4   },
      { name: "4-8",   left_height: 4,  right_height: 8   },
      { name: "8-12",  left_height: 8,  right_height: 12  },
      { name: "12-16", left_height: 12, right_height: 16  },

      { name: "16-8",  left_height: 16, right_height: 8   },
      { name: "8-0",   left_height: 8,  right_height: 0   },
      { name: "0-8",   left_height: 0,  right_height: 8   },
      { name: "8-16",  left_height: 8,  right_height: 16  },

      { name: "0-0",   left_height: 0,  right_height: 0   },
      { name: "8-8",   left_height: 8,  right_height: 8   },
      { name: "16-16", left_height: 16, right_height: 16  },
    ]

    # toolbar data representation which will be used to render the toolbar.
    # the buttons array will be used to render the buttons
    # the toolbar_rect will be used to restrict the creation of tiles
    # within the toolbar area
    args.state.toolbar = {
      toolbar_rect: nil,
      buttons: []
    }

    # for each tile definition, create a button
    args.state.toolbar.buttons = tile_definitions.map_with_index do |spec, index|
      left_height  = spec.left_height
      right_height = spec.right_height
      button_size  = 48
      column_size  = 15
      column_padding = 2
      column = index % column_size
      column_padding = column * column_padding
      margin = 10
      row = index.idiv(column_size)
      row_padding = row * 2
      x = margin + column_padding + (column * button_size)
      y = (margin + button_size + row_padding + (row * button_size)).from_top

      # when a tile is added, the data of this button will be used
      # to construct the terrain

      # each tile has an x, y, w, h which represents the bounding box
      # of the button.
      # the button also contains the left_height and right_height which is
      # important when determining collision of the ramps
      {
        name: spec.name,
        left_height: left_height,
        right_height: right_height,
        button_rect: {
          x: x,
          y: y,
          w: 48,
          h: 48
        }
      }
    end

    # with the buttons populated, compute the bounding box of the entire
    # toolbar (again this will be used to restrict the creation of tiles)
    min_x = args.state.toolbar.buttons.map { |t| t.button_rect.x }.min
    min_y = args.state.toolbar.buttons.map { |t| t.button_rect.y }.min

    max_x = args.state.toolbar.buttons.map { |t| t.button_rect.x }.max
    max_y = args.state.toolbar.buttons.map { |t| t.button_rect.y }.max

    args.state.toolbar.rect = {
      x: min_x - 10,
      y: min_y - 10,
      w: max_x - min_x + 10 + 64,
      h: max_y - min_y + 10 + 64
    }
  end

  # set the selected tile to the last button in the toolbar
  args.state.selected_tile ||= args.state.toolbar.buttons.last

  # ================================================
  # starting terrain generation
  # ================================================
  if !args.state.terrain
    world = [
      { row: 14, col: 25, name: "0-8"   },
      { row: 14, col: 26, name: "8-16"  },
      { row: 15, col: 27, name: "0-8"   },
      { row: 15, col: 28, name: "8-16"  },
      { row: 16, col: 29, name: "0-8"   },
      { row: 16, col: 30, name: "8-16"  },
      { row: 17, col: 31, name: "0-8"   },
      { row: 17, col: 32, name: "8-16"  },
      { row: 18, col: 33, name: "0-8"   },
      { row: 18, col: 34, name: "8-16"  },
      { row: 18, col: 35, name: "16-12" },
      { row: 18, col: 36, name: "12-8"  },
      { row: 18, col: 37, name: "8-4"   },
      { row: 18, col: 38, name: "4-0"   },
      { row: 18, col: 39, name: "0-0"   },
      { row: 18, col: 40, name: "0-0"   },
      { row: 18, col: 41, name: "0-0"   },
      { row: 18, col: 42, name: "0-4"   },
      { row: 18, col: 43, name: "4-8"   },
      { row: 18, col: 44, name: "8-12"  },
      { row: 18, col: 45, name: "12-16" },
    ]

    args.state.terrain = world.map do |tile|
      template = tile_by_name(args, tile.name)
      next if !template
      grid_rect = grid_rect_for(tile.row, tile.col)
      new_terrain_definition(grid_rect, template)
    end
  end

  # ================================================
  # toolbar input and rendering
  # ================================================
  # store the mouse position alligned to the tile grid
  mouse_grid_aligned_rect = grid_aligned_rect args.inputs.mouse, 16

  # determine if the mouse intersects the toolbar
  mouse_intersects_toolbar = args.state.toolbar.rect.intersect_rect? args.inputs.mouse

  # determine if the mouse intersects a toolbar button
  toolbar_button = args.state.toolbar.buttons.find { |t| t.button_rect.intersect_rect? args.inputs.mouse }

  # determine if the mouse click occurred over a tile in the terrain
  terrain_tile = args.geometry.find_intersect_rect mouse_grid_aligned_rect, args.state.terrain


  # if a mouse click occurs....
  if args.inputs.mouse.click
    if toolbar_button
      # if a toolbar button was clicked, set the currently selected tile to the toolbar tile
      args.state.selected_tile = toolbar_button
    elsif terrain_tile
      # if a tile was clicked, delete it from the terrain
      args.state.terrain.delete terrain_tile
    elsif !args.state.toolbar.rect.intersect_rect? args.inputs.mouse
      # if the mouse was not clicked in the toolbar area
      # add a new terrain based off of the information in the selected tile
      args.state.terrain << new_terrain_definition(mouse_grid_aligned_rect, args.state.selected_tile)
    end
  end

  # render a light blue background for the toolbar button that is currently
  # being hovered over (if any)
  if toolbar_button
    args.outputs.primitives << toolbar_button.button_rect.merge(primitive_marker: :solid, a: 64, b: 255)
  end

  # put a blue background around the currently selected tile
  args.outputs.primitives << args.state.selected_tile.button_rect.merge(primitive_marker: :solid, b: 255, r: 128, a: 64)

  if !mouse_intersects_toolbar
    if terrain_tile
      # if the mouse is hoving over an existing terrain tile, render a red border around the
      # tile to signify that it will be deleted if the mouse is clicked
      args.outputs.borders << terrain_tile.merge(a: 255, r: 255)
    else
      # if the mouse is not hovering over an existing terrain tile, render the currently
      # selected tile at the mouse position
      grid_aligned_rect = grid_aligned_rect args.inputs.mouse, 16

      args.outputs.solids << {
        **grid_aligned_rect,
        a: 30,
        g: 128
      }

      args.outputs.lines << {
        x:  grid_aligned_rect.x,
        y:  grid_aligned_rect.y + args.state.selected_tile.left_height,
        x2: grid_aligned_rect.x + grid_aligned_rect.w,
        y2: grid_aligned_rect.y + args.state.selected_tile.right_height,
      }
    end
  end

  # render each toolbar button using two primitives, a border to denote
  # the click area of the button, and a line to denote the terrain that
  # will be created when the button is clicked
  args.outputs.primitives << args.state.toolbar.buttons.map do |toolbar_tile|
    primitives = []
    scale = toolbar_tile.button_rect.w / 16

    primitive_type = :border

    [
      {
        **toolbar_tile.button_rect,
        primitive_marker: primitive_type,
        a: 64,
        g: 128
      },
      {
        x:  toolbar_tile.button_rect.x,
        y:  toolbar_tile.button_rect.y + toolbar_tile.left_height * scale,
        x2: toolbar_tile.button_rect.x + toolbar_tile.button_rect.w,
        y2: toolbar_tile.button_rect.y + toolbar_tile.right_height * scale
      }
    ]
  end
end

# ================================================
# helper methods
#=================================================

# converts a row and column on the grid to
# a rect
def grid_rect_for row, col
  { x: col * 16, y: row * 16, w: 16, h: 16 }
end

# find a tile by name
def tile_by_name args, name
  args.state.toolbar.buttons.find { |b| b.name == name }
end

# data structure containing terrain information
# specifcially tile.left_height and tile.right_height
def new_terrain_definition grid_rect, tile
  grid_rect.merge(
    tile: tile,
    line: {
      x:  grid_rect.x,
      y:  grid_rect.y + tile.left_height,
      x2: grid_rect.x + grid_rect.w,
      y2: grid_rect.y + tile.right_height
    }
  )
end

# helper method that returns a grid aligned rect given
# an arbitrary rect and a grid size
def grid_aligned_rect point, size
  grid_aligned_x = point.x - (point.x % size)
  grid_aligned_y = point.y - (point.y % size)
  { x: grid_aligned_x.to_i, y: grid_aligned_y.to_i, w: size.to_i, h: size.to_i }
end

    Mouse link

    Mouse Click - main.rb link

    # ./samples/05_mouse/01_mouse_click/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - product: Returns an array of all combinations of elements from all arrays.

   For example, [1,2].product([1,2]) would return the following array...
   [[1,1], [1,2], [2,1], [2,2]]
   More than two arrays can be given to product and it will still work,
   such as [1,2].product([1,2],[3,4]). What would product return in this case?

   Answer:
   [[1,1,3],[1,1,4],[1,2,3],[1,2,4],[2,1,3],[2,1,4],[2,2,3],[2,2,4]]

 - num1.fdiv(num2): Returns the float division (will have a decimal) of the two given numbers.
   For example, 5.fdiv(2) = 2.5 and 5.fdiv(5) = 1.0

 - yield: Allows you to call a method with a code block and yield to that block.

 Reminders:

 - Hash#inside_rect?: Returns true or false depending on if the point is inside the rect.

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

 - args.inputs.mouse.click: This property will be set if the mouse was clicked.

 - Ternary operator (?): Will evaluate a statement (just like an if statement)
   and perform an action if the result is true or another action if it is false.

 - reject: Removes elements from a collection if they meet certain requirements.

 - args.outputs.borders: An array. The values generate a border.
   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
   For more information about borders, go to mygame/documentation/03-solids-and-borders.md.

 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.

=end

# This sample app is a classic game of Tic Tac Toe.
class TicTacToe
  attr_gtk # class macro that adds outputs, inputs, state, etc to class

  def tick
    init_new_game
    render_board
    input_board
  end

  def init_new_game
    state.current_turn       ||= :x
    state.space_combinations ||= [-1, 0, 1].product([-1, 0, 1]).to_a
    if !state.spaces
      state.square_size ||= 80
      state.board_left  ||= grid.w_half - state.square_size * 1.5
      state.board_top   ||= grid.h_half - state.square_size * 1.5
      state.spaces = {}
      state.space_combinations.each do |x, y|
        state.spaces[x]    ||= {}
        state.spaces[x][y] ||= {}
        state.spaces[x][y].hitbox ||= {
          x: state.board_left + (x + 1) * state.square_size,
          y: state.board_top  + (y + 1) * state.square_size,
          w: state.square_size,
          h: state.square_size
        }
      end
    end
  end

  # Uses borders to create grid squares for the game's board. Also outputs the game pieces using labels.
  def render_board
    # At first glance, the add(1) looks pretty trivial. But if you remove it,
    # you'll see that the positioning of the board would be skewed without it!
    # Or if you put 2 in the parenthesis, the pieces will be placed in the wrong squares
    # due to the change in board placement.
    outputs.borders << all_spaces.map do |space| # outputs borders for all board spaces
                         space.hitbox
                       end

    hovered_box = all_spaces.find do |space|
      inputs.mouse.inside_rect?(space.hitbox) && !space.piece
    end

    if hovered_box && !state.game_over
      args.outputs.solids << { x: hovered_box.hitbox.x,
                               y: hovered_box.hitbox.y,
                               w: hovered_box.hitbox.w,
                               h: hovered_box.hitbox.h,
                               r: 0,
                               g: 100,
                               b: 200,
                               a: 80 }
    end

    # put label in each filled space of board
    outputs.labels << filled_spaces.map do |space|
      { x: space.hitbox.x + space.hitbox.w / 2,
        y: space.hitbox.y + space.hitbox.h / 2,
        anchor_x: 0.5,
        anchor_y: 0.5,
        size_px: 40,
        text: space.piece }
    end

    # Uses a label to output whether x or o won, or if a draw occurred.
    # If the game is ongoing, a label shows whose turn it currently is.
    outputs.labels << if state.x_won
                        { x: 640, y: 600, text: "x won", size_px: 40, anchor_x: 0.5, anchor_y: 0.5 }
                      elsif state.o_won
                        { x: 640, y: 600, text: "o won", size_px: 40, anchor_x: 0.5, anchor_y: 0.5 }
                      elsif state.draw
                        { x: 640, y: 600, text: "draw", size_px: 40, anchor_x: 0.5, anchor_y: 0.5 }
                      else
                        { x: 640, y: 600, text: "turn: #{state.current_turn}", size_px: 40, anchor_x: 0.5, anchor_y: 0.5 }
                      end
  end

  # Calls the methods responsible for handling user input and determining the winner.
  # Does nothing unless the mouse is clicked.
  def input_board
    return unless inputs.mouse.click
    input_place_piece
    input_restart_game
    determine_winner
  end

  # Handles user input for placing pieces on the board.
  def input_place_piece
    return if state.game_over

    # Checks to find the space that the mouse was clicked inside of, and makes sure the space does not already
    # have a piece in it.
    space = all_spaces.find do |space|
      inputs.mouse.click.point.inside_rect?(space.hitbox) && !space.piece
    end

    # The piece that goes into the space belongs to the player whose turn it currently is.
    return unless space

    space.piece = state.current_turn

    # This ternary operator statement allows us to change the current player's turn.
    # If it is currently x's turn, it becomes o's turn. If it is not x's turn, it become's x's turn.
    state.current_turn = state.current_turn == :x ? :o : :x
  end

  # Resets the game.
  def input_restart_game
    return unless state.game_over
    gtk.reset
    init_new_game
  end

  # Checks if x or o won the game.
  # If neither player wins and all nine squares are filled, a draw happens.
  # Once a player is chosen as the winner or a draw happens, the game is over.
  def determine_winner
    state.x_won = won? :x # evaluates to either true or false (boolean values)
    state.o_won = won? :o
    state.draw = true if filled_spaces.length == 9 && !state.x_won && !state.o_won
    state.game_over = state.x_won || state.o_won || state.draw
  end

  # Determines if a player won by checking if there is a horizontal match or vertical match.
  # Horizontal_match and vertical_match have boolean values. If either is true, the game has been won.
  def won? piece
    # performs action on all space combinations
    won = [[-1, 0, 1]].product([-1, 0, 1]).map do |xs, y|
      # Checks if the 3 grid spaces with the same y value (or same row) and
      # x values that are next to each other have pieces that belong to the same player.
      # Remember, the value of piece is equal to the current turn (which is the player).
      horizontal_match = state.spaces[xs[0]][y].piece == piece &&
                         state.spaces[xs[1]][y].piece == piece &&
                         state.spaces[xs[2]][y].piece == piece

      # Checks if the 3 grid spaces with the same x value (or same column) and
      # y values that are next to each other have pieces that belong to the same player.
      # The && represents an "and" statement: if even one part of the statement is false,
      # the entire statement evaluates to false.
      vertical_match = state.spaces[y][xs[0]].piece == piece &&
                       state.spaces[y][xs[1]].piece == piece &&
                       state.spaces[y][xs[2]].piece == piece

      horizontal_match || vertical_match # if either is true, true is returned
    end

    # Sees if there is a diagonal match, starting from the bottom left and ending at the top right.
    # Is added to won regardless of whether the statement is true or false.
    won << (state.spaces[-1][-1].piece == piece && # bottom left
            state.spaces[ 0][ 0].piece == piece && # center
            state.spaces[ 1][ 1].piece == piece)   # top right

    # Sees if there is a diagonal match, starting at the bottom right and ending at the top left
    # and is added to won.
    won << (state.spaces[ 1][-1].piece == piece && # bottom right
            state.spaces[ 0][ 0].piece == piece && # center
            state.spaces[-1][ 1].piece == piece)   # top left

    # Any false statements (meaning false diagonal matches) are rejected from won
    won.reject_false.any?
  end

  # Defines filled spaces on the board by rejecting all spaces that do not have game pieces in them.
  # The ! before a statement means "not". For example, we are rejecting any space combinations that do
  # NOT have pieces in them.
  def filled_spaces
    all_spaces.reject { |space| !space.piece } # reject spaces with no pieces in them
  end

  # Defines all spaces on the board.
  def all_spaces
    state.space_combinations.map do |x, y|
      state.spaces[x][y] # yield if a block is given
    end
  end
end

$tic_tac_toe = nil

def tick args
  args.outputs.labels << { x: 640,
                           y: 700,
                           anchor_x: 0.5,
                           anchor_y: 0.5,
                           text: "Sample app shows how to work with mouse clicks and hitboxes." }
  $tic_tac_toe ||= TicTacToe.new
  $tic_tac_toe.args = args
  $tic_tac_toe.tick
end

    Mouse Move - main.rb link

    # ./samples/05_mouse/02_mouse_move/app/main.rb
=begin

 Reminders:

 - find_all: Finds all elements of a collection that meet certain requirements.
   For example, in this sample app, we're using find_all to find all zombies that have intersected
   or hit the player's sprite since these zombies have been killed.

 - args.inputs.keyboard.key_down.KEY: Determines if a key is being held or pressed.
   Stores the frame the "down" event occurred.
   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.

 - args.outputs.sprites: An array. The values generate a sprite.
   The parameters are [X, Y, WIDTH, HEIGHT, PATH, ANGLE, ALPHA, RED, GREEN, BLUE]
   For more information about sprites, go to mygame/documentation/05-sprites.md.

 - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
   When we want to create a new object, we can declare it as a new entity and then define
   its properties. (Remember, you can use state to define ANY property and it will
   be retained across frames.)

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

 - map: Ruby method used to transform data; used in arrays, hashes, and collections.
   Can be used to perform an action on every element of a collection, such as multiplying
   each element by 2 or declaring every element as a new entity.

 - sample: Chooses a random element from the array.

 - reject: Removes elements that meet certain requirements.
   In this sample app, we're removing/rejecting zombies that reach the center of the screen. We're also
   rejecting zombies that were killed more than 30 frames ago.

=end

# This sample app allows users to move around the screen in order to kill zombies. Zombies appear from every direction so the goal
# is to kill the zombies as fast as possible!

class ProtectThePuppiesFromTheZombies
  attr_accessor :grid, :inputs, :state, :outputs

  # Calls the methods necessary for the game to run properly.
  def tick
    defaults
    render
    calc
    input
  end

  # Sets default values for the zombies and for the player.
  # Initialization happens only in the first frame.
  def defaults
    state.flash_at               ||= 0
    state.zombie_min_spawn_rate  ||= 60
    state.zombie_spawn_countdown ||= random_spawn_countdown state.zombie_min_spawn_rate
    state.zombies                ||= []
    state.killed_zombies         ||= []

    # Declares player as a new entity and sets its properties.
    # The player begins the game in the center of the screen, not moving in any direction.
    state.player ||= { x: 640,
                       y: 360,
                       w: 4 * 3,
                       h: 8 * 3,
                       attack_angle: 0,
                       dx: 0,
                       dy: 0,
                       created_at: state.tick_count }
  end

  # Outputs a gray background.
  # Calls the methods needed to output the player, zombies, etc onto the screen.
  def render
    outputs.background_color = [100, 100, 100]
    render_zombies
    render_killed_zombies
    render_player
    render_flash
  end

  # Outputs the zombies on the screen and sets values for the sprites, such as the position, width, height, and animation.
  def render_zombies
    outputs.sprites << state.zombies.map do |z| # performs action on all zombies in the collection
      z.merge path: animation_sprite(z)  # sets definition for sprite, calls animation_sprite method
    end
  end

  # Outputs sprites of killed zombies, and displays a slash image to show that a zombie has been killed.
  def render_killed_zombies
    outputs.sprites << state.killed_zombies.map do |z| # performs action on all killed zombies in collection
      zombie = { x: z.x,
                 y: z.y,
                 w: 4 * 3,
                 h: 8 * 3,
                 path: animation_sprite(z, z.death_at), # calls animation_sprite method
                 a: 255 * z.death_at.ease(30, :flip) }  # transparency of a zombie changes when they die

      # Sets values to output the slash over the zombie's sprite when a zombie is killed.
      # The slash is tilted 45 degrees from the angle of the player's attack.
      # Change the 3 inside scale_rect to 30 and the slash will be HUGE! Scale_rect positions
      # the slash over the killed zombie's sprite.
      [zombie,
       zombie.merge(path: 'sprites/slash.png',
                    angle: 45 + (state.player.attack_angle_on_click || 0)).scale_rect(3, 0.5, 0.5)]
    end
  end

  # Outputs the player sprite using the images in the sprites folder.
  def render_player
    # Outputs a small red square that previews the angles that the player can attack in.
    # It can be moved in a perfect circle around the player to show possible movements.
    # Change the 60 in the parenthesis and see what happens to the movement of the red square.
    outputs.sprites << { x: state.player.x + state.player.attack_angle.vector_x(60),
                         y: state.player.y + state.player.attack_angle.vector_y(60),
                         w: 3,
                         h: 3,
                         r: 255,
                         g: 0,
                         b: 0,
                         path: :solid }

    outputs.sprites << { x: state.player.x,
                         y: state.player.y,
                         w: 4 * 3,
                         h: 8 * 3,
                         path: "sprites/player-#{animation_index(state.player.created_at.elapsed_time)}.png" } # string interpolation
  end

  # Renders flash as a solid. The screen turns white for 10 frames when a zombie is killed.
  def render_flash
    return if state.flash_at.elapsed_time > 10 # return if more than 10 frames have passed since flash.
    # Transparency gradually changes (or eases) during the 10 frames of flash.
    outputs.primitives << { **grid.rect, r: 255, g: 255, b: 255, a: 255 * state.flash_at.ease(10, :flip), path: :solid }
  end

  # Calls all methods necessary for performing calculations.
  def calc
    calc_spawn_zombie
    calc_move_zombies
    calc_player
    calc_kill_zombie
  end

  # Decreases the zombie spawn countdown by 1 if it has a value greater than 0.
  def calc_spawn_zombie
    if state.zombie_spawn_countdown > 0
      state.zombie_spawn_countdown -= 1
      return
    end

    # New zombies are created, positioned on the screen, and added to the zombies collection.
    state.zombies << (if rand > 0.5
                       {
                         x: grid.rect.w.randomize(:ratio), # random x position on screen (within grid scope)
                         y: [-10, 730].sample, # y position is set to either -10 or 730 (randomly chosen)
                         w: 4 * 3, h: 8 * 3,
                         created_at: state.tick_count
                       }
                      else
                       {
                         x: [-10, 1290].sample, # x position is set to either -10 or 1290 (randomly chosen)
                         y: grid.rect.w.randomize(:ratio), # random y position on screen
                         w: 4 * 3, h: 8 * 3,
                         created_at: state.tick_count
                       }
                      end)

    # Calls random_spawn_countdown method (determines how fast new zombies appear)
    state.zombie_spawn_countdown = random_spawn_countdown state.zombie_min_spawn_rate
    state.zombie_min_spawn_rate -= 1
    # set to either the current zombie_min_spawn_rate or 0, depending on which value is greater
    state.zombie_min_spawn_rate  = state.zombie_min_spawn_rate.clamp(0)
  end

  # Moves all zombies towards the center of the screen.
  # All zombies that reach the center (640, 360) are rejected from the zombies collection and disappear.
  def calc_move_zombies
    state.zombies.each do |z| # for each zombie in the collection
      z.y = z.y.towards(360, 0.1) # move the zombie towards the center (640, 360) at a rate of 0.1
      z.x = z.x.towards(640, 0.1) # change 0.1 to 1.1 and see how much faster the zombies move to the center
    end
    state.zombies = state.zombies.reject { |z| z.y == 360 && z.x == 640 } # remove zombies that are in center
  end

  # Calculates the position and movement of the player on the screen.
  def calc_player
    state.player.x += state.player.dx # changes x based on dx (change in x)
    state.player.y += state.player.dy # changes y based on dy (change in y)

    state.player.dx *= 0.9 # scales dx down
    state.player.dy *= 0.9 # scales dy down

    # Compares player's x to 1280 to find lesser value, then compares result to 0 to find greater value.
    # This ensures that the player remains within the screen's scope.
    state.player.x = state.player.x.clamp(0, 1280)
    state.player.y = state.player.y.clamp(0, 720) # same with player's y
  end

  # Finds all zombies that intersect with the player's sprite. These zombies are removed from the zombies collection
  # and added to the killed_zombies collection since any zombie that intersects with the player is killed.
  def calc_kill_zombie

    # Find all zombies that intersect with the player. They are considered killed.
    killed_this_frame = state.zombies.find_all { |z| (z.intersect_rect? state.player) }
    state.zombies = state.zombies - killed_this_frame # remove newly killed zombies from zombies collection
    state.killed_zombies += killed_this_frame # add newly killed zombies to killed zombies

    if killed_this_frame.length > 0 # if atleast one zombie was killed in the frame
      state.flash_at = state.tick_count # flash_at set to the frame when the zombie was killed
    # Don't forget, the rendered flash lasts for 10 frames after the zombie is killed (look at render_flash method)
    end

    # Sets the tick_count (passage of time) as the value of the death_at variable for each killed zombie.
    # Death_at stores the frame a zombie was killed.
    killed_this_frame.each do |z|
      z.death_at = state.tick_count
    end

    # Zombies are rejected from the killed_zombies collection depending on when they were killed.
    # They are rejected if more than 30 frames have passed since their death.
    state.killed_zombies = state.killed_zombies.reject { |z| state.tick_count - z.death_at > 30 }
  end

  # Uses input from the user to move the player around the screen.
  def input

    # If the "a" key or left key is pressed, the x position of the player decreases.
    # Otherwise, if the "d" key or right key is pressed, the x position of the player increases.
    if inputs.keyboard.key_held.a || inputs.keyboard.key_held.left
      state.player.x -= 5
    elsif inputs.keyboard.key_held.d || inputs.keyboard.key_held.right
      state.player.x += 5
    end

    # If the "w" or up key is pressed, the y position of the player increases.
    # Otherwise, if the "s" or down key is pressed, the y position of the player decreases.
    if inputs.keyboard.key_held.w || inputs.keyboard.key_held.up
      state.player.y += 5
    elsif inputs.keyboard.key_held.s || inputs.keyboard.key_held.down
      state.player.y -= 5
    end

    # Sets the attack angle so the player can move and attack in the precise direction it wants to go.
    # If the mouse is moved, the attack angle is changed (based on the player's position and mouse position).
    # Attack angle also contributes to the position of red square.
    if inputs.mouse.moved
      state.player.attack_angle = inputs.mouse.position.angle_from [state.player.x, state.player.y]
    end

    if inputs.mouse.click && state.player.dx < 0.5 && state.player.dy < 0.5
      state.player.attack_angle_on_click = inputs.mouse.position.angle_from [state.player.x, state.player.y]
      state.player.attack_angle = state.player.attack_angle_on_click # player's attack angle is set
      state.player.dx = state.player.attack_angle.vector_x(25) # change in player's position
      state.player.dy = state.player.attack_angle.vector_y(25)
    end
  end

  # Sets the zombie spawn's countdown to a random number.
  # How fast zombies appear (change the 60 to 6 and too many zombies will appear at once!)
  def random_spawn_countdown minimum
    10.randomize(:ratio, :sign).to_i + 60
  end

  # Helps to iterate through the images in the sprites folder by setting the animation index.
  # 3 frames is how long to show an image, and 6 is how many images to flip through.
  def animation_index at
    at.idiv(3).mod(6)
  end

  # Animates the zombies by using the animation index to go through the images in the sprites folder.
  def animation_sprite zombie, at = nil
    at ||= zombie.created_at.elapsed_time # how long it is has been since a zombie was created
    index = animation_index at
    "sprites/zombie-#{index}.png" # string interpolation to iterate through images
  end
end

$protect_the_puppies_from_the_zombies = ProtectThePuppiesFromTheZombies.new

def tick args
  $protect_the_puppies_from_the_zombies.grid    = args.grid
  $protect_the_puppies_from_the_zombies.inputs  = args.inputs
  $protect_the_puppies_from_the_zombies.state    = args.state
  $protect_the_puppies_from_the_zombies.outputs = args.outputs
  $protect_the_puppies_from_the_zombies.tick
  tick_instructions args, "How to get the mouse position and translate it to an x, y position using .vector_x and .vector_y. CLICK to play."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Mouse Move Paint App - main.rb link

    # ./samples/05_mouse/03_mouse_move_paint_app/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - Floor: Method that returns an integer number smaller than or equal to the original with no decimal.

   For example, if we have a variable, a = 13.7, and we called floor on it, it would look like this...
   puts a.floor()
   which would print out 13.
   (There is also a ceil method, which returns an integer number greater than or equal to the original
   with no decimal. If we had called ceil on the variable a, the result would have been 14.)

 Reminders:

 - Hashes: Collection of unique keys and their corresponding values. The value can be found
   using their keys.

   For example, if we have a "numbers" hash that stores numbers in English as the
   key and numbers in Spanish as the value, we'd have a hash that looks like this...
   numbers = { "one" => "uno", "two" => "dos", "three" => "tres" }
   and on it goes.

   Now if we wanted to find the corresponding value of the "one" key, we could say
   puts numbers["one"]
   which would print "uno" to the console.

 - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
   In this sample app, new_entity is used to create a new button that clears the grid.
   (Remember, you can use state to define ANY property and it will be retained across frames.)

 - args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.

 - args.inputs.mouse.click.point.created_at: The frame the mouse click occurred in.

 - args.outputs.labels: An array. The values in the array generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - ARRAY#inside_rect?: Returns true or false depending on if the point is inside the rect.

=end

# This sample app shows an empty grid that the user can paint on.
# To paint, the user must keep their mouse presssed and drag it around the grid.
# The "clear" button allows users to clear the grid so they can start over.

class PaintApp
  attr_accessor :inputs, :state, :outputs, :grid, :args

  # Runs methods necessary for the game to function properly.
  def tick
    print_title
    add_grid
    check_click
    draw_buttons
  end

  # Prints the title onto the screen by using a label.
  # Also separates the title from the grid with a line as a horizontal separator.
  def print_title
    args.outputs.labels << [ 640, 700, 'Paint!', 0, 1 ]
    outputs.lines << horizontal_separator(660, 0, 1280)
  end

  # Sets the starting position, ending position, and color for the horizontal separator.
  # The starting and ending positions have the same y values.
  def horizontal_separator y, x, x2
    [x, y, x2, y, 150, 150, 150]
  end

  # Sets the starting position, ending position, and color for the vertical separator.
  # The starting and ending positions have the same x values.
  def vertical_separator x, y, y2
    [x, y, x, y2, 150, 150, 150]
  end

  # Outputs a border and a grid containing empty squares onto the screen.
  def add_grid

    # Sets the x, y, height, and width of the grid.
    # There are 31 horizontal lines and 31 vertical lines in the grid.
    # Feel free to count them yourself before continuing!
    x, y, h, w = 640 - 500/2, 640 - 500, 500, 500 # calculations done so the grid appears in screen's center
    lines_h = 31
    lines_v = 31

    # Sets values for the grid's border, grid lines, and filled squares.
    # The filled_squares variable is initially set to an empty array.
    state.grid_border ||= [ x, y, h, w ] # definition of grid's outer border
    state.grid_lines ||= draw_grid(x, y, h, w, lines_h, lines_v) # calls draw_grid method
    state.filled_squares ||= [] # there are no filled squares until the user fills them in

    # Outputs the grid lines, border, and filled squares onto the screen.
    outputs.lines.concat state.grid_lines
    outputs.borders << state.grid_border
    outputs.solids << state.filled_squares
  end

  # Draws the grid by adding in vertical and horizontal separators.
  def draw_grid x, y, h, w, lines_h, lines_v

    # The grid starts off empty.
    grid = []

    # Calculates the placement and adds horizontal lines or separators into the grid.
    curr_y = y # start at the bottom of the box
    dist_y = h / (lines_h + 1) # finds distance to place horizontal lines evenly throughout 500 height of grid
    lines_h.times do
      curr_y += dist_y # increment curr_y by the distance between the horizontal lines
      grid << horizontal_separator(curr_y, x, x + w - 1) # add a separator into the grid
    end

    # Calculates the placement and adds vertical lines or separators into the grid.
    curr_x = x # now start at the left of the box
    dist_x = w / (lines_v + 1) # finds distance to place vertical lines evenly throughout 500 width of grid
    lines_v.times do
      curr_x += dist_x # increment curr_x by the distance between the vertical lines
      grid << vertical_separator(curr_x, y + 1, y  + h) # add separator
    end

    # paint_grid uses a hash to assign values to keys.
    state.paint_grid ||= {"x" => x, "y" => y, "h" => h, "w" => w, "lines_h" => lines_h,
                          "lines_v" => lines_v, "dist_x" => dist_x,
                          "dist_y" => dist_y }

    return grid
  end

  # Checks if the user is keeping the mouse pressed down and sets the mouse_hold variable accordingly using boolean values.
  # If the mouse is up, the user cannot drag the mouse.
  def check_click
    if inputs.mouse.down #is mouse up or down?
      state.mouse_held = true # mouse is being held down
    elsif inputs.mouse.up # if mouse is up
    state.mouse_held = false # mouse is not being held down or dragged
      state.mouse_dragging = false
    end

    if state.mouse_held &&    # mouse needs to be down
      !inputs.mouse.click &&     # must not be first click
      ((inputs.mouse.previous_click.point.x - inputs.mouse.position.x).abs > 15) # Need to move 15 pixels before "drag"
      state.mouse_dragging = true
    end

    # If the user clicks their mouse inside the grid, the search_lines method is called with a click input type.
    if ((inputs.mouse.click) && (inputs.mouse.click.point.inside_rect? state.grid_border))
      search_lines(inputs.mouse.click.point, :click)

    # If the user drags their mouse inside the grid, the search_lines method is called with a drag input type.
    elsif ((state.mouse_dragging) && (inputs.mouse.position.inside_rect? state.grid_border))
      search_lines(inputs.mouse.position, :drag)
    end
  end

  # Sets the definition of a grid box and handles user input to fill in or clear grid boxes.
  def search_lines (point, input_type)
    point.x -= state.paint_grid["x"] # subtracts the value assigned to the "x" key in the paint_grid hash
    point.y -= state.paint_grid["y"] # subtracts the value assigned to the "y" key in the paint_grid hash

    # Remove code following the .floor and see what happens when you try to fill in grid squares
    point.x = (point.x / state.paint_grid["dist_x"]).floor * state.paint_grid["dist_x"]
    point.y = (point.y / state.paint_grid["dist_y"]).floor * state.paint_grid["dist_y"]

    point.x += state.paint_grid["x"]
    point.y += state.paint_grid["y"]

    # Sets definition of a grid box, meaning its x, y, width, and height.
    # Floor is called on the point.x and point.y variables.
    # Ceil method is called on values of the distance hash keys, setting the width and height of a box.
    grid_box = [ point.x.floor, point.y.floor, state.paint_grid["dist_x"].ceil, state.paint_grid["dist_y"].ceil ]

    if input_type == :click # if user clicks their mouse
      if state.filled_squares.include? grid_box # if grid box is already filled in
        state.filled_squares.delete grid_box # box is cleared and removed from filled_squares
      else
        state.filled_squares << grid_box # otherwise, box is filled in and added to filled_squares
      end
    elsif input_type == :drag # if user drags mouse
      unless state.filled_squares.include? grid_box # unless the grid box dragged over is already filled in
        state.filled_squares << grid_box # the box is filled in and added to filled_squares
      end
    end
  end

  # Creates and outputs a "Clear" button on the screen using a label and a border.
  # If the button is clicked, the filled squares are cleared, making the filled_squares collection empty.
  def draw_buttons
    x, y, w, h = 390, 50, 240, 50
    state.clear_button        ||= state.new_entity(:button_with_fade)

    # The x and y positions are set to display the label in the center of the button.
    # Try changing the first two parameters to simply x, y and see what happens to the text placement!
    state.clear_button.label  ||= [x + w.half, y + h.half + 10, "Clear", 0, 1] # placed in center of border
    state.clear_button.border ||= [x, y, w, h]

    # If the mouse is clicked inside the borders of the clear button,
    # the filled_squares collection is emptied and the squares are cleared.
    if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.clear_button.border)
      state.clear_button.clicked_at = inputs.mouse.click.created_at # time (frame) the click occurred
      state.filled_squares.clear
      inputs.mouse.previous_click = nil
    end

    outputs.labels << state.clear_button.label
    outputs.borders << state.clear_button.border

    # When the clear button is clicked, the color of the button changes
    # and the transparency changes, as well. If you change the time from
    # 0.25.seconds to 1.25.seconds or more, the change will last longer.
    if state.clear_button.clicked_at
      outputs.solids << [x, y, w, h, 0, 180, 80, 255 * state.clear_button.clicked_at.ease(0.25.seconds, :flip)]
    end
  end
end

$paint_app = PaintApp.new

def tick args
  $paint_app.inputs = args.inputs
  $paint_app.state = args.state
  $paint_app.grid = args.grid
  $paint_app.args = args
  $paint_app.outputs = args.outputs
  $paint_app.tick
  tick_instructions args, "How to create a simple paint app. CLICK and HOLD to draw."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Coordinate Systems - main.rb link

    # ./samples/05_mouse/04_coordinate_systems/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - args.inputs.mouse.click.position: Coordinates of the mouse's position on the screen.
   Unlike args.inputs.mouse.click.point, the mouse does not need to be pressed down for
   position to know the mouse's coordinates.
   For more information about the mouse, go to mygame/documentation/07-mouse.md.

 Reminders:

 - args.inputs.mouse.click: This property will be set if the mouse was clicked.

 - args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

   In this sample app, string interpolation is used to show the current position of the mouse
   in a label.

 - args.outputs.labels: An array that generates a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - args.outputs.solids: An array that generates a solid.
   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE, ALPHA]
   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.

 - args.outputs.lines: An array that generates a line.
   The parameters are [X, Y, X2, Y2, RED, GREEN, BLUE, ALPHA]
   For more information about lines, go to mygame/documentation/04-lines.md.

=end

# This sample app shows a coordinate system or grid. The user can move their mouse around the screen and the
# coordinates of their position on the screen will be displayed. Users can choose to view one quadrant or
# four quadrants by pressing the button.

def tick args

  # The addition and subtraction in the first two parameters of the label and solid
  # ensure that the outputs don't overlap each other. Try removing them and see what happens.
  pos = args.inputs.mouse.position # stores coordinates of mouse's position
  args.outputs.labels << [pos.x + 10, pos.y + 10, "#{pos}"] # outputs label of coordinates
  args.outputs.solids << [pos.x -  2, pos.y - 2, 5, 5] # outputs small blackk box placed where mouse is hovering

  button = [0, 0, 370, 50] # sets definition of toggle button
  args.outputs.borders << button # outputs button as border (not filled in)
  args.outputs.labels << [10, 35, "click here toggle coordinate system"] # label of button
  args.outputs.lines << [    0, -720,    0, 720] # vertical line dividing quadrants
  args.outputs.lines << [-1280,    0, 1280,   0] # horizontal line dividing quadrants

  if args.inputs.mouse.click # if the user clicks the mouse
    pos = args.inputs.mouse.click.point # pos's value is point where user clicked (coordinates)
    if pos.inside_rect? button # if the click occurred inside the button
      if args.grid.name == :bottom_left # if the grid shows bottom left as origin
        args.grid.origin_center! # origin will be shown in center
      else
        args.grid.origin_bottom_left! # otherwise, the view will change to show bottom left as origin
      end
    end
  end

  tick_instructions args, "Sample app shows the two supported coordinate systems in Game Toolkit."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Clicking Buttons - main.rb link

    # ./samples/05_mouse/05_clicking_buttons/app/main.rb
def tick args
  # create buttons
  args.state.buttons ||= [
    create_button(args, id: :button_1, row: 0, col: 0, text: "button 1"),
    create_button(args, id: :button_2, row: 1, col: 0, text: "button 2"),
    create_button(args, id: :clear,    row: 2, col: 0, text: "clear")
  ]

  # render button's border and label
  args.outputs.primitives << args.state.buttons.map do |b|
    b.primitives
  end

  # render center label if the text is set
  if args.state.center_label_text
    args.outputs.labels << { x: 640,
                             y: 360,
                             text: args.state.center_label_text,
                             alignment_enum: 1,
                             vertical_alignment_enum: 1 }
  end

  # if the mouse is clicked, see if the mouse click intersected
  # with a button
  if args.inputs.mouse.click
    button = args.state.buttons.find do |b|
      args.inputs.mouse.intersect_rect? b
    end

    # update the center label text based on button clicked
    case button.id
    when :button_1
      args.state.center_label_text = "button 1 was clicked"
    when :button_2
      args.state.center_label_text = "button 2 was clicked"
    when :clear
      args.state.center_label_text = nil
    end
  end
end

def create_button args, id:, row:, col:, text:;
  # args.layout.rect(row:, col:, w:, h:) is method that will
  # return a rectangle inside of a grid with 12 rows and 24 columns
  rect = args.layout.rect row: row, col: col, w: 3, h: 1

  # get senter of rect for label
  center = args.geometry.rect_center_point rect

  {
    id: id,
    x: rect.x,
    y: rect.y,
    w: rect.w,
    h: rect.h,
    primitives: [
      {
        x: rect.x,
        y: rect.y,
        w: rect.w,
        h: rect.h,
        primitive_marker: :border
      },
      {
        x: center.x,
        y: center.y,
        text: text,
        size_enum: -1,
        alignment_enum: 1,
        vertical_alignment_enum: 1,
        primitive_marker: :label
      }
    ]
  }
end

$gtk.reset

    Save Load link

    Reading Writing Files - main.rb link

    # ./samples/06_save_load/00_reading_writing_files/app/main.rb
# APIs covered:
#   args.gtk.write_file "file-1.txt", args.state.tick_count.to_s
#   args.gtk.append_file "file-1.txt", args.state.tick_count.to_s

#   stat = args.gtk.stat_file "file-1.txt"

#   contents = args.gtk.read_file "file-1.txt"

#   args.gtk.delete_file "file-1.txt"
#   args.gtk.delete_file_if_exist "file-1.txt"

#   root_files = args.gtk.list_files ""
#   app_files  = args.gtk.list_files "app"

def tick args
  # create buttons
  args.state.buttons ||= [
    create_button(args, id: :write_file_1,  row: 0, col: 0, text: "write file-1.txt"),
    create_button(args, id: :append_file_1, row: 1, col: 0, text: "append file-1.txt"),
    create_button(args, id: :delete_file_1, row: 2, col: 0, text: "delete file-1.txt"),

    create_button(args, id: :read_file_1,   row: 0, col: 3, text: "read file-1.txt"),
    create_button(args, id: :stat_file_1,   row: 1, col: 3, text: "stat file-1.txt"),
    create_button(args, id: :list_files,    row: 2, col: 3, text: "list files"),
  ]

  # render button's border and label
  args.outputs.primitives << args.state.buttons.map do |b|
    b.primitives
  end

  # render center label if the text is set
  if args.state.center_label_text
    long_string = args.state.center_label_text
    max_character_length = 80
    long_strings_split = args.string.wrapped_lines long_string, max_character_length
    line_height = 23
    offset = (long_strings_split.length / 2) * line_height
    args.outputs.labels << long_strings_split.map_with_index do |s, i|
      {
        x: 400,
        y: 60.from_top - (i * line_height),
        text: s
      }
    end
  end

  # if the mouse is clicked, see if the mouse click intersected
  # with a button
  if args.inputs.mouse.click
    button = args.state.buttons.find do |b|
      args.inputs.mouse.intersect_rect? b
    end

    # update the center label text based on button clicked
    case button.id
    when :write_file_1
      args.gtk.write_file("file-1.txt", args.state.tick_count.to_s + "\n")

      args.state.center_label_text = ""
      args.state.center_label_text += "* Success (#{args.state.tick_count}):\n"
      args.state.center_label_text += "  Click \"read file-1.txt\" to see the contents.\n"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "** Sample Code\n"
      args.state.center_label_text += "   args.gtk.write_file(\"file-1.txt\", args.state.tick_count.to_s + \"\\n\")\n"
    when :append_file_1
      args.gtk.append_file("file-1.txt", args.state.tick_count.to_s + "\n")

      args.state.center_label_text = ""
      args.state.center_label_text += "* Success (#{args.state.tick_count}):\n"
      args.state.center_label_text += "  Click \"read file-1.txt\" to see the contents.\n"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "** Sample Code\n"
      args.state.center_label_text += "   args.gtk.append_file(\"file-1.txt\", args.state.tick_count.to_s + \"\\n\")\n"
    when :stat_file_1
      stat = args.gtk.stat_file "file-1.txt"

      args.state.center_label_text = ""
      args.state.center_label_text += "* Stat File (#{args.state.tick_count})\n"
      args.state.center_label_text += "#{stat || "nil (file does not exist)"}"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "** Sample Code\n"
      args.state.center_label_text += "   args.gtk.stat_files(\"file-1.txt\")\n"
    when :read_file_1
      contents = args.gtk.read_file("file-1.txt")

      args.state.center_label_text = ""
      if contents
        args.state.center_label_text += "* Contents (#{args.state.tick_count}):\n"
        args.state.center_label_text += contents
        args.state.center_label_text += "\n"
        args.state.center_label_text += "** Sample Code\n"
        args.state.center_label_text += "   contents = args.gtk.read_file(\"file-1.txt\")\n"
      else
        args.state.center_label_text += "* Contents (#{args.state.tick_count}):\n"
        args.state.center_label_text += "Contents of file was nil. Click stat file-1.txt for file information."
        args.state.center_label_text += "\n"
        args.state.center_label_text += "** Sample Code\n"
        args.state.center_label_text += "   contents = args.gtk.read_file(\"file-1.txt\")\n"
      end
    when :delete_file_1
      args.state.center_label_text = ""

      if args.gtk.stat_file "file-1.txt"
        args.gtk.delete_file "file-1.txt"
        args.state.center_label_text += "* Delete File\n"
        args.state.center_label_text += "file-1.txt was deleted. Click \"list files\" or \"stat file-1.txt\" for more info."
        args.state.center_label_text += "\n"
        args.state.center_label_text += "\n"
        args.state.center_label_text += "** Sample Code\n"
        args.state.center_label_text += "   args.gtk.delete_file(\"file-1.txt\")\n"
      else
        args.state.center_label_text = ""
        args.state.center_label_text += "* Delete File\n"
        args.state.center_label_text += "File does not exist. Click \"write file-1.txt\" or \"append file-1.txt\" to create file."
        args.state.center_label_text += "\n"
        args.state.center_label_text += "\n"
        args.state.center_label_text += "** Sample Code\n"
        args.state.center_label_text += "   if args.gtk.stat_file(\"file-1.txt\") ...\n"
      end
    when :list_files
      root_files = args.gtk.list_files ""
      app_files  = args.gtk.list_files "app"

      args.state.center_label_text = ""
      args.state.center_label_text += "** Root Files (#{args.state.tick_count}):\n"
      args.state.center_label_text += root_files.join "\n"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "** App Files (#{args.state.tick_count}):\n"
      args.state.center_label_text += app_files.join "\n"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "\n"
      args.state.center_label_text += "** Sample Code\n"
      args.state.center_label_text += "   root_files = args.gtk.list_files(\"\")\n"
      args.state.center_label_text += "   app_files = args.gtk.list_files(\"app\")\n"
    end
  end
end

def create_button args, id:, row:, col:, text:;
  # args.layout.rect(row:, col:, w:, h:) is method that will
  # return a rectangle inside of a grid with 12 rows and 24 columns
  rect = args.layout.rect row: row, col: col, w: 3, h: 1

  # get senter of rect for label
  center = args.geometry.rect_center_point rect

  {
    id: id,
    x: rect.x,
    y: rect.y,
    w: rect.w,
    h: rect.h,
    primitives: [
      {
        x: rect.x,
        y: rect.y,
        w: rect.w,
        h: rect.h,
        primitive_marker: :border
      },
      {
        x: center.x,
        y: center.y,
        text: text,
        size_enum: -2,
        alignment_enum: 1,
        vertical_alignment_enum: 1,
        primitive_marker: :label
      }
    ]
  }
end

$gtk.reset

    Save Load Game - main.rb link

    # ./samples/06_save_load/01_save_load_game/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - Symbol (:): Ruby object with a name and an internal ID. Symbols are useful
   because with a given symbol name, you can refer to the same object throughout
   a Ruby program.

   In this sample app, we're using symbols for our buttons. We have buttons that
   light fires, save, load, etc. Each of these buttons has a distinct symbol like
   :light_fire, :save_game, :load_game, etc.

 - to_sym: Returns the symbol corresponding to the given string; creates the symbol
   if it does not already exist.
   For example,
   'car'.to_sym
   would return the symbol :car.

 - last: Returns the last element of an array.

 Reminders:

 - num1.lesser(num2): finds the lower value of the given options.
   For example, in the statement
   a = 4.lesser(3)
   3 has a lower value than 4, which means that the value of a would be set to 3,
   but if the statement had been
   a = 4.lesser(5)
   4 has a lower value than 5, which means that the value of a would be set to 4.

 - num1.fdiv(num2): returns the float division (will have a decimal) of the two given numbers.
   For example, 5.fdiv(2) = 2.5 and 5.fdiv(5) = 1.0

 - String interpolation: uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

 - args.outputs.labels: An array. Values generate a label.
   Parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information, go to mygame/documentation/02-labels.md.

 - ARRAY#inside_rect?: An array with at least two values is considered a point. An array
   with at least four values is considered a rect. The inside_rect? function returns true
   or false depending on if the point is inside the rect.

=end

# This code allows users to perform different tasks, such as saving and loading the game.
# Users also have options to reset the game and light a fire.

class TextedBasedGame

  # Contains methods needed for game to run properly.
  # Increments tick count by 1 each time it runs (60 times in a single second)
  def tick
    default
    show_intro
    state.engine_tick_count += 1
    tick_fire
  end

  # Sets default values.
  # The ||= ensures that a variable's value is only set to the value following the = sign
  # if the value has not already been set before. Intialization happens only in the first frame.
  def default
    state.engine_tick_count ||= 0
    state.active_module     ||= :room
    state.fire_progress     ||= 0
    state.fire_ready_in     ||= 10
    state.previous_fire     ||= :dead
    state.fire              ||= :dead
  end

  def show_intro
    return unless state.engine_tick_count == 0 # return unless the game just started
    set_story_line "awake." # calls set_story_line method, sets to "awake"
  end

  # Sets story line.
  def set_story_line story_line
    state.story_line    = story_line # story line set to value of parameter
    state.active_module = :alert # active module set to alert
  end

  # Clears story line.
  def clear_storyline
    state.active_module = :none # active module set to none
    state.story_line = nil # story line is cleared, set to nil (or empty)
  end

  # Determines fire progress (how close the fire is to being ready to light).
  def tick_fire
    return if state.active_module == :alert # return if active module is alert
    state.fire_progress += 1 # increment fire progress
    # fire_ready_in is 10. The fire_progress is either the current value or 10, whichever has a lower value.
    state.fire_progress = state.fire_progress.lesser(state.fire_ready_in)
  end

  # Sets the value of fire (whether it is dead or roaring), and the story line
  def light_fire
    return unless fire_ready? # returns unless the fire is ready to be lit
    state.fire = :roaring # fire is lit, set to roaring
    state.fire_progress = 0 # the fire progress returns to 0, since the fire has been lit
    if state.fire != state.previous_fire
      set_story_line "the fire is #{state.fire}." # the story line is set using string interpolation
      state.previous_fire = state.fire
    end
  end

  # Checks if the fire is ready to be lit. Returns a boolean value.
  def fire_ready?
    # If fire_progress (value between 0 and 10) is equal to fire_ready_in (value of 10),
    # the fire is ready to be lit.
    state.fire_progress == state.fire_ready_in
  end

  # Divides the value of the fire_progress variable by 10 to determine how close the user is to
  # being able to light a fire.
  def light_fire_progress
    state.fire_progress.fdiv(10) # float division
  end

  # Defines fire as the state.fire variable.
  def fire
    state.fire
  end

  # Sets the title of the room.
  def room_title
    return "a room that is dark" if state.fire == :dead # room is dark if the fire is dead
    return "a room that is lit" # room is lit if the fire is not dead
  end

  # Sets the active_module to room.
  def go_to_room
    state.active_module = :room
  end

  # Defines active_module as the state.active_module variable.
  def active_module
    state.active_module
  end

  # Defines story_line as the state.story_line variable.
  def story_line
    state.story_line
  end

  # Update every 60 frames (or every second)
  def should_tick?
    state.tick_count.mod_zero?(60)
  end

  # Sets the value of the game state provider.
  def initialize game_state_provider
    @game_state_provider = game_state_provider
  end

  # Defines the game state.
  # Any variable prefixed with an @ symbol is an instance variable.
  def state
    @game_state_provider.state
  end

  # Saves the state of the game in a text file called game_state.txt.
  def save
    $gtk.serialize_state('game_state.txt', state)
  end

  # Loads the game state from the game_state.txt text file.
  # If the load is unsuccessful, the user is informed since the story line indicates the failure.
  def load
    parsed_state = $gtk.deserialize_state('game_state.txt')
    if !parsed_state
      set_story_line "no game to load. press save first."
    else
      $gtk.args.state = parsed_state
    end
  end

  # Resets the game.
  def reset
    $gtk.reset
  end
end

class TextedBasedGamePresenter
  attr_accessor :state, :outputs, :inputs

  # Creates empty collection called highlights.
  # Calls methods necessary to run the game.
  def tick
    state.layout.highlights ||= []
    game.tick if game.should_tick?
    render
    process_input
  end

  # Outputs a label of the tick count (passage of time) and calls all render methods.
  def render
    outputs.labels << [10, 30, state.tick_count]
    render_alert
    render_room
    render_highlights
  end

  # Outputs a label onto the screen that shows the story line, and also outputs a "close" button.
  def render_alert
    return unless game.active_module == :alert

    outputs.labels << [640, 480, game.story_line, 5, 1]  # outputs story line label
    outputs.primitives << button(:alert_dismiss, 490, 380, "close")  # positions "close" button under story line
  end

  def render_room
    return unless game.active_module == :room
    outputs.labels << [640, 700, game.room_title, 4, 1] # outputs room title label at top of screen

    # The parameters for these outputs are (symbol, x, y, text, value/percentage) and each has a y value
    # that positions it 60 pixels lower than the previous output.

    # outputs the light_fire_progress bar, uses light_fire_progress for its percentage (which changes bar's appearance)
    outputs.primitives << progress_bar(:light_fire, 490, 600, "light fire", game.light_fire_progress)
    outputs.primitives << button(       :save_game, 490, 540, "save") # outputs save button
    outputs.primitives << button(       :load_game, 490, 480, "load") # outputs load button
    outputs.primitives << button(      :reset_game, 490, 420, "reset") # outputs reset button
    outputs.labels << [640, 30, "the fire is #{game.fire}", 0, 1] # outputs fire label at bottom of screen
  end

  # Outputs a collection of highlights using an array to set their values, and also rejects certain values from the collection.
  def render_highlights
    state.layout.highlights.each do |h| # for each highlight in the collection
        h.lifetime -= 1 # decrease the value of its lifetime
      end

      outputs.solids << state.layout.highlights.map do |h| # outputs highlights collection
        [h.x, h.y, h.w, h.h, h.color, 255 * h.lifetime / h.max_lifetime] # sets definition for each highlight
        # transparency changes; divide lifetime by max_lifetime, multiply result by 255
      end

      # reject highlights from collection that have no remaining lifetime
      state.layout.highlights = state.layout.highlights.reject { |h| h.lifetime <= 0 }
  end

  # Checks whether or not a button was clicked.
  # Returns a boolean value.
  def process_input
    button = button_clicked? # calls button_clicked? method
  end

  # Returns a boolean value.
  # Finds the button that was clicked from the button list and determines what method to call.
  # Adds a highlight to the highlights collection.
  def button_clicked?
    return nil unless click_pos # return nil unless click_pos holds coordinates of mouse click
      button = @button_list.find do |k, v| # goes through button_list to find button clicked
        click_pos.inside_rect? v[:primitives].last.rect # was the mouse clicked inside the rect of button?
      end
      return unless button # return unless a button was clicked
      method_to_call = "#{button[0]}_clicked".to_sym # sets method_to_call to symbol (like :save_game or :load_game)
      if self.respond_to? method_to_call # returns true if self responds to the given method (method actually exists)
        border = button[1][:primitives].last # sets border definition using value of last key in button list hash

        # declares each highlight as a new entity, sets properties
        state.layout.highlights << state.new_entity(:highlight) do |h|
            h.x = border.x
            h.y = border.y
            h.w = border.w
            h.h = border.h
            h.max_lifetime = 10
            h.lifetime = h.max_lifetime
            h.color = [120, 120, 180] # sets color to shade of purple
          end

          self.send method_to_call # invoke method identified by symbol
        else # otherwise, if self doesn't respond to given method
          border = button[1][:primitives].last # sets border definition using value of last key in hash

          # declares each highlight as a new entity, sets properties
          state.layout.highlights << state.new_entity(:highlight) do |h|
            h.x = border.x
            h.y = border.y
            h.w = border.w
            h.h = border.h
            h.max_lifetime = 4 # different max_lifetime than the one set if respond_to? had been true
            h.lifetime = h.max_lifetime
            h.color = [120, 80, 80] # sets color to dark color
          end

          # instructions for users on how to add the missing method_to_call to the code
          puts "It looks like #{method_to_call} doesn't exists on TextedBasedGamePresenter. Please add this method:"
          puts "Just copy the code below and put it in the #{TextedBasedGamePresenter} class definition."
          puts ""
          puts "```"
          puts "class TextedBasedGamePresenter <--- find this class and put the method below in it"
          puts ""
          puts "  def #{method_to_call}"
          puts "    puts 'Yay that worked!'"
          puts "  end"
          puts ""
          puts "end <-- make sure to put the #{method_to_call} method in between the `class` word and the final `end` statement."
          puts "```"
          puts ""
      end
  end

  # Returns the position of the mouse when it is clicked.
  def click_pos
    return nil unless inputs.mouse.click # returns nil unless the mouse was clicked
    return inputs.mouse.click.point # returns location of mouse click (coordinates)
  end

  # Creates buttons for the button_list and sets their values using a hash (uses symbols as keys)
  def button id, x, y, text
    @button_list[id] ||= { # assigns values to hash keys
      id: id,
      text: text,
      primitives: [
        [x + 10, y + 30, text, 2, 0].label, # positions label inside border
        [x, y, 300, 50].border,             # sets definition of border
      ]
    }

    @button_list[id][:primitives] # returns label and border for buttons
  end

  # Creates a progress bar (used for lighting the fire) and sets its values.
  def progress_bar id, x, y, text, percentage
    @button_list[id] = { # assigns values to hash keys
      id: id,
      text: text,
      primitives: [
        [x, y, 300, 50, 100, 100, 100].solid, # sets definition for solid (which fills the bar with gray)
        [x + 10, y + 30, text, 2, 0].label, # sets definition for label, positions inside border
        [x, y, 300, 50].border, # sets definition of border
      ]
    }

    # Fills progress bar based on percentage. If the fire was ready to be lit (100%) and we multiplied by
    # 100, only 1/3 of the bar would only be filled in. 200 would cause only 2/3 to be filled in.
    @button_list[id][:primitives][0][2] = 300 * percentage
    @button_list[id][:primitives]
  end

  # Defines the game.
  def game
    @game
  end

  # Initalizes the game and creates an empty list of buttons.
  def initialize
    @game = TextedBasedGame.new self
    @button_list ||= {}
  end

  # Clears the storyline and takes the user to the room.
  def alert_dismiss_clicked
    game.clear_storyline
    game.go_to_room
  end

  # Lights the fire when the user clicks the "light fire" option.
  def light_fire_clicked
    game.light_fire
  end

  # Saves the game when the user clicks the "save" option.
  def save_game_clicked
    game.save
  end

  # Resets the game when the user clicks the "reset" option.
  def reset_game_clicked
    game.reset
  end

  # Loads the game when the user clicks the "load" option.
  def load_game_clicked
    game.load
  end
end

$text_based_rpg = TextedBasedGamePresenter.new

def tick args
  $text_based_rpg.state = args.state
  $text_based_rpg.outputs = args.outputs
  $text_based_rpg.inputs = args.inputs
  $text_based_rpg.tick
end

    Advanced Audio link

    Audio Mixer - main.rb link

    # ./samples/07_advanced_audio/01_audio_mixer/app/main.rb
# these are the properties that you can sent on args.audio
def spawn_new_sound args, name, path
  # Spawn randomly in an area that won't be covered by UI.
  screenx = (rand * 600.0) + 200.0
  screeny = (rand * 400.0) + 100.0

  id = new_sound_id! args
  # you can hang anything on the audio hashes you want, so we store the
  #  actual screen position in here for convenience.
  args.audio[id] = {
    name: name,
    input: path,
    screenx: screenx,
    screeny: screeny,
    x: ((screenx / 1279.0) * 2.0) - 1.0,  # scale to -1.0 - 1.0 range
    y: ((screeny / 719.0) * 2.0) - 1.0,   # scale to -1.0 - 1.0 range
    z: 0.0,
    gain: 1.0,
    pitch: 1.0,
    looping: true,
    paused: false
  }

  args.state.selected = id
end

# these are values you can change on the ~args.audio~ data structure
def input_panel args
  return unless args.state.panel
  return if args.state.dragging

  audio_entry = args.audio[args.state.selected]
  results = args.state.panel

  if args.state.mouse_state == :held && args.inputs.mouse.position.inside_rect?(results.pitch_slider_rect.rect)
    audio_entry.pitch = 2.0 * ((args.inputs.mouse.x - results.pitch_slider_rect.rect.x).to_f / (results.pitch_slider_rect.rect.w - 1.0))
  elsif args.state.mouse_state == :held && args.inputs.mouse.position.inside_rect?(results.playtime_slider_rect.rect)
    audio_entry.playtime = audio_entry.length_ * ((args.inputs.mouse.x - results.playtime_slider_rect.rect.x).to_f / (results.playtime_slider_rect.rect.w - 1.0))
  elsif args.state.mouse_state == :held && args.inputs.mouse.position.inside_rect?(results.gain_slider_rect.rect)
    audio_entry.gain = (args.inputs.mouse.x - results.gain_slider_rect.rect.x).to_f / (results.gain_slider_rect.rect.w - 1.0)
  elsif args.inputs.mouse.click && args.inputs.mouse.position.inside_rect?(results.looping_checkbox_rect.rect)
    audio_entry.looping = !audio_entry.looping
  elsif args.inputs.mouse.click && args.inputs.mouse.position.inside_rect?(results.paused_checkbox_rect.rect)
    audio_entry.paused = !audio_entry.paused
  elsif args.inputs.mouse.click && args.inputs.mouse.position.inside_rect?(results.delete_button_rect.rect)
    args.audio.delete args.state.selected
  end
end

def render_sources args
  args.outputs.primitives << args.audio.keys.map do |k|
    s = args.audio[k]

    isselected = (k == args.state.selected)

    color = isselected ? [ 0, 255, 0, 255 ] : [ 0, 0, 255, 255 ]
    [
      [s.screenx, s.screeny, args.state.boxsize, args.state.boxsize, *color].solid,

      {
        x: s.screenx + args.state.boxsize.half,
        y: s.screeny,
        text: s.name,
        r: 255,
        g: 255,
        b: 255,
        alignment_enum: 1
      }.label!
    ]
  end
end

def playtime_str t
  return "" unless t
  minutes = (t / 60.0).floor
  seconds = t - (minutes * 60.0).to_f
  return minutes.to_s + ':' + seconds.floor.to_s + ((seconds - seconds.floor).to_s + "000")[1..3]
end

def label_with_drop_shadow x, y, text
  [
    { x: x + 1, y: y + 1, text: text, vertical_alignment_enum: 1, alignment_enum: 1, r:   0, g:   0, b:   0 }.label!,
    { x: x + 2, y: y + 0, text: text, vertical_alignment_enum: 1, alignment_enum: 1, r:   0, g:   0, b:   0 }.label!,
    { x: x + 0, y: y + 1, text: text, vertical_alignment_enum: 1, alignment_enum: 1, r: 200, g: 200, b: 200 }.label!
  ]
end

def check_box opts = {}
  checkbox_template = opts.args.layout.rect(w: 0.5, h: 0.5, col: 2)
  final_rect = checkbox_template.center_inside_rect_y(opts.args.layout.rect(row: opts.row, col: opts.col))
  color = { r:   0, g:   0, b:   0 }
  color = { r: 255, g: 255, b: 255 } if opts.checked

  {
    rect: final_rect,
    primitives: [
      (final_rect.to_solid color)
    ]
  }
end

def progress_bar opts = {}
  outer_rect  = opts.args.layout.rect(row: opts.row, col: opts.col, w: 5, h: 1)
  color = opts.percentage * 255
  baseline_progress_bar = opts.args
                              .layout
                              .rect(w: 5, h: 0.5)

  final_rect = baseline_progress_bar.center_inside_rect(outer_rect)
  center = final_rect.rect_center_point

  {
    rect: final_rect,
    primitives: [
      final_rect.merge(r: color, g: color, b: color, a: 128).solid!,
      label_with_drop_shadow(center.x, center.y, opts.text)
    ]
  }
end

def panel_primitives args, audio_entry
  results = { primitives: [] }

  return results unless audio_entry

  # this uses DRGTK's layout apis to layout the controls
  # imagine the screen is split into equal cells (24 cells across, 12 cells up and down)
  # args.layout.rect returns a hash which we merge values with to create primitives
  # using args.layout.rect removes the need for pixel pushing

  # args.outputs.debug << args.layout.debug_primitives(r: 255, g: 255, b: 255)

  white_color = { r: 255, g: 255, b: 255 }
  label_style = white_color.merge(vertical_alignment_enum: 1)

  # panel background
  results.primitives << args.layout.rect(row: 0, col: 0, w: 7, h: 6, include_col_gutter: true, include_row_gutter: true)
                                   .border!(r: 255, g: 255, b: 255)

  # title
  results.primitives << args.layout.point(row: 0, col: 3.5, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text:           "Source #{args.state.selected} (#{args.audio[args.state.selected].name})",
                                          size_enum:      3,
                                          alignment_enum: 1)

  # seperator line
  results.primitives << args.layout.rect(row: 1, col: 0, w: 7, h: 0)
                                   .line!(white_color)

  # screen location
  results.primitives << args.layout.point(row: 1.0, col: 0, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "screen:")

  results.primitives << args.layout.point(row: 1.0, col: 2, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "(#{audio_entry.screenx.to_i}, #{audio_entry.screeny.to_i})")

  # position
  results.primitives << args.layout.point(row: 1.5, col: 0, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "position:")

  results.primitives << args.layout.point(row: 1.5, col: 2, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "(#{audio_entry[:x].round(5).to_s[0..6]}, #{audio_entry[:y].round(5).to_s[0..6]})")

  results.primitives << args.layout.point(row: 2.0, col: 0, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "pitch:")

  results.pitch_slider_rect = progress_bar(row: 2.0, col: 2,
                                           percentage: audio_entry.pitch / 2.0,
                                           text: "#{audio_entry.pitch.to_sf}",
                                           args: args)

  results.primitives << results.pitch_slider_rect.primitives

  results.primitives << args.layout.point(row: 2.5, col: 0, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "playtime:")

  results.playtime_slider_rect = progress_bar(args: args,
                                              row:  2.5,
                                              col:  2,
                                              percentage: (audio_entry.playtime || 1) / (audio_entry.length_ || 1),
                                              text: "#{playtime_str(audio_entry.playtime)} / #{playtime_str(audio_entry.length_)}")

  results.primitives << results.playtime_slider_rect.primitives

  results.primitives << args.layout.point(row: 3.0, col: 0, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "gain:")

  results.gain_slider_rect = progress_bar(args: args,
                                          row:  3.0,
                                          col:  2,
                                          percentage: audio_entry.gain,
                                          text: "#{audio_entry.gain.to_sf}")

  results.primitives << results.gain_slider_rect.primitives


  results.primitives << args.layout.point(row: 3.5, col: 0, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "looping:")

  checkbox_template = args.layout.rect(w: 0.5, h: 0.5, col: 2)

  results.looping_checkbox_rect = check_box(args: args, row: 3.5, col: 2, checked: audio_entry.looping)
  results.primitives << results.looping_checkbox_rect.primitives

  results.primitives << args.layout.point(row: 4.0, col: 0, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "paused:")

  checkbox_template = args.layout.rect(w: 0.5, h: 0.5, col: 2)

  results.paused_checkbox_rect = check_box(args: args, row: 4.0, col: 2, checked: !audio_entry.paused)
  results.primitives << results.paused_checkbox_rect.primitives

  results.delete_button_rect = { rect: args.layout.rect(row: 5, col: 0, w: 7, h: 1) }

  results.primitives << results.delete_button_rect.rect.to_solid(r: 180)

  results.primitives << args.layout.point(row: 5, col: 3.5, row_anchor: 0.5)
                                   .merge(label_style)
                                   .merge(text: "DELETE", alignment_enum: 1)

  return results
end

def render_panel args
  args.state.panel = nil
  audio_entry = args.audio[args.state.selected]
  return unless audio_entry

  mouse_down = (args.state.mouse_held >= 0)
  args.state.panel = panel_primitives args, audio_entry
  args.outputs.primitives << args.state.panel.primitives
end

def new_sound_id! args
  args.state.sound_id ||= 0
  args.state.sound_id  += 1
  args.state.sound_id
end

def render_launcher args
  args.outputs.primitives << args.state.spawn_sound_buttons.map(&:primitives)
end

def render_ui args
  render_launcher args
  render_panel args
end

def tick args
  defaults args
  render args
  input args
end

def input args
  if !args.audio[args.state.selected]
    args.state.selected = nil
    args.state.dragging = nil
  end

  # spawn button and node interaction
  if args.inputs.mouse.click
    spawn_sound_button = args.state.spawn_sound_buttons.find { |b| args.inputs.mouse.inside_rect? b.rect }

    audio_click_key, audio_click_value = args.audio.find do |k, v|
      args.inputs.mouse.inside_rect? [v.screenx, v.screeny, args.state.boxsize, args.state.boxsize]
    end

    if spawn_sound_button
      args.state.selected = nil
      spawn_new_sound args, spawn_sound_button.name, spawn_sound_button.path
    elsif audio_click_key
      args.state.selected = audio_click_key
    end
  end

  if args.state.mouse_state == :held && args.state.selected
    v = args.audio[args.state.selected]
    if args.inputs.mouse.inside_rect? [v.screenx, v.screeny, args.state.boxsize, args.state.boxsize]
      args.state.dragging = args.state.selected
    end

    if args.state.dragging
      s = args.audio[args.state.selected]
      # you can hang anything on the audio hashes you want, so we store the
      #  actual screen position so it doesn't scale weirdly vs your mouse.
      s.screenx = args.inputs.mouse.x - (args.state.boxsize / 2)
      s.screeny = args.inputs.mouse.y - (args.state.boxsize / 2)

      s.screeny = 50 if s.screeny < 50
      s.screeny = (719 - args.state.boxsize) if s.screeny > (719 - args.state.boxsize)
      s.screenx = 0 if s.screenx < 0
      s.screenx = (1279 - args.state.boxsize) if s.screenx > (1279 - args.state.boxsize)

      s.x = ((s.screenx / 1279.0) * 2.0) - 1.0  # scale to -1.0 - 1.0 range
      s.y = ((s.screeny / 719.0) * 2.0) - 1.0   # scale to -1.0 - 1.0 range
    end
  elsif args.state.mouse_state == :released
    args.state.dragging = nil
  end

  input_panel args
end

def defaults args
  args.state.mouse_state      ||= :released
  args.state.dragging_source  ||= false
  args.state.selected         ||= 0
  args.state.next_sound_index ||= 0
  args.state.boxsize          ||= 30
  args.state.sound_files      ||= [
    { name: :tada,   path: "sounds/tada.wav"   },
    { name: :splash, path: "sounds/splash.wav" },
    { name: :drum,   path: "sounds/drum.mp3"   },
    { name: :spring, path: "sounds/spring.wav" },
    { name: :music,  path: "sounds/music.ogg"  }
  ]

  # generate buttons based off the sound collection above
  args.state.spawn_sound_buttons ||= begin
    # create a group of buttons
    # column centered (using col_offset to calculate the column offset)
    # where each item is 2 columns apart
    rects = args.layout.rect_group row:   11,
                                   col_offset: {
                                     count: args.state.sound_files.length,
                                     w:     2
                                   },
                                   dcol:  2,
                                   w:     2,
                                   h:     1,
                                   group: args.state.sound_files

    # now that you have the rects
    # construct the metadata for the buttons
    rects.map do |rect|
      {
        rect: rect,
        name: rect.name,
        path: rect.path,
        primitives: [
          rect.to_border(r: 255, g: 255, b: 255),
          rect.to_label(x: rect.center_x,
                        y: rect.center_y,
                        text: "#{rect.name}",
                        alignment_enum: 1,
                        vertical_alignment_enum: 1,
                        r: 255, g: 255, b: 255)
        ]
      }
    end
  end

  if args.inputs.mouse.up
    args.state.mouse_state = :released
    args.state.dragging_source = false
  elsif args.inputs.mouse.down
    args.state.mouse_state = :held
  end

  args.outputs.background_color = [ 0, 0, 0, 255 ]
end

def render args
  render_ui args
  render_sources args
end

    Audio Mixer - server_ip_address.txt link

    # ./samples/07_advanced_audio/01_audio_mixer/app/server_ip_address.txt
192.168.1.65

    Sound Synthesis - main.rb link

    # ./samples/07_advanced_audio/02_sound_synthesis/app/main.rb
begin # region: top level tick methods
  def tick args
    defaults args
    render args
    input args
    process_audio_queue args
  end

  def defaults args
    args.state.sine_waves      ||= {}
    args.state.square_waves    ||= {}
    args.state.saw_tooth_waves ||= {}
    args.state.triangle_waves  ||= {}
    args.state.audio_queue     ||= []
    args.state.buttons         ||= [
      (frequency_buttons args),
      (sine_wave_note_buttons args),
      (bell_buttons args),
      (square_wave_note_buttons args),
      (saw_tooth_wave_note_buttons args),
      (triangle_wave_note_buttons args),
    ].flatten
  end

  def render args
    args.outputs.borders << args.state.buttons.map { |b| b[:border] }
    args.outputs.labels  << args.state.buttons.map { |b| b[:label]  }
  end

  def input args
    args.state.buttons.each do |b|
      if args.inputs.mouse.click && (args.inputs.mouse.click.inside_rect? b[:rect])
        parameter_string = (b.slice :frequency, :note, :octave).map { |k, v| "#{k}: #{v}" }.join ", "
        args.gtk.notify! "#{b[:method_to_call]} #{parameter_string}"
        send b[:method_to_call], args, b
      end
    end

    if args.inputs.mouse.click && (args.inputs.mouse.click.inside_rect? (args.layout.rect(row: 0).yield_self { |r| r.merge y: r.y + r.h.half, h: r.h.half }))
      args.gtk.openurl 'https://www.youtube.com/watch?v=zEzovM5jT-k&ab_channel=AmirRajan'
    end
  end

  def process_audio_queue args
    to_queue = args.state.audio_queue.find_all { |v| v[:queue_at] <= args.tick_count }
    args.state.audio_queue -= to_queue
    to_queue.each { |a| args.audio[a[:id]] = a }

    args.audio.find_all { |k, v| v[:decay_rate] }
      .each     { |k, v| v[:gain] -= v[:decay_rate] }

    sounds_to_stop = args.audio
                       .find_all { |k, v| v[:stop_at] && args.state.tick_count >= v[:stop_at] }
                       .map { |k, v| k }

    sounds_to_stop.each { |k| args.audio.delete k }
  end
end

begin # region: button definitions, ui layout, callback functions
  def button args, opts
    button_def = opts.merge rect: (args.layout.rect (opts.merge w: 2, h: 1))

    button_def[:border] = button_def[:rect].merge r: 0, g: 0, b: 0

    label_offset_x = 5
    label_offset_y = 30

    button_def[:label]  = button_def[:rect].merge text: opts[:text],
                                                  size_enum: -2.5,
                                                  x: button_def[:rect].x + label_offset_x,
                                                  y: button_def[:rect].y + label_offset_y

    button_def
  end

  def play_sine_wave args, sender
    queue_sine_wave args,
                    frequency: sender[:frequency],
                    duration: 1.seconds,
                    fade_out: true
  end

  def play_note args, sender
    method_to_call = :queue_sine_wave
    method_to_call = :queue_square_wave    if sender[:type] == :square
    method_to_call = :queue_saw_tooth_wave if sender[:type] == :saw_tooth
    method_to_call = :queue_triangle_wave  if sender[:type] == :triangle
    method_to_call = :queue_bell           if sender[:type] == :bell

    send method_to_call, args,
         frequency: (frequency_for note: sender[:note], octave: sender[:octave]),
         duration: 1.seconds,
         fade_out: true
  end

  def frequency_buttons args
    [
      (button args,
              row: 4.0, col: 0, text: "300hz",
              frequency: 300,
              method_to_call: :play_sine_wave),
      (button args,
              row: 5.0, col: 0, text: "400hz",
              frequency: 400,
              method_to_call: :play_sine_wave),
      (button args,
              row: 6.0, col: 0, text: "500hz",
              frequency: 500,
              method_to_call: :play_sine_wave),
    ]
  end

  def sine_wave_note_buttons args
    [
      (button args,
              row: 1.5, col: 2, text: "Sine C4",
              note: :c, octave: 4, type: :sine, method_to_call: :play_note),
      (button args,
              row: 2.5, col: 2, text: "Sine D4",
              note: :d, octave: 4, type: :sine, method_to_call: :play_note),
      (button args,
              row: 3.5, col: 2, text: "Sine E4",
              note: :e, octave: 4, type: :sine, method_to_call: :play_note),
      (button args,
              row: 4.5, col: 2, text: "Sine F4",
              note: :f, octave: 4, type: :sine, method_to_call: :play_note),
      (button args,
              row: 5.5, col: 2, text: "Sine G4",
              note: :g, octave: 4, type: :sine, method_to_call: :play_note),
      (button args,
              row: 6.5, col: 2, text: "Sine A5",
              note: :a, octave: 5, type: :sine, method_to_call: :play_note),
      (button args,
              row: 7.5, col: 2, text: "Sine B5",
              note: :b, octave: 5, type: :sine, method_to_call: :play_note),
      (button args,
              row: 8.5, col: 2, text: "Sine C5",
              note: :c, octave: 5, type: :sine, method_to_call: :play_note),
    ]
  end

  def square_wave_note_buttons args
    [
      (button args,
              row: 1.5, col: 6, text: "Square C4",
              note: :c, octave: 4, type: :square, method_to_call: :play_note),
      (button args,
              row: 2.5, col: 6, text: "Square D4",
              note: :d, octave: 4, type: :square, method_to_call: :play_note),
      (button args,
              row: 3.5, col: 6, text: "Square E4",
              note: :e, octave: 4, type: :square, method_to_call: :play_note),
      (button args,
              row: 4.5, col: 6, text: "Square F4",
              note: :f, octave: 4, type: :square, method_to_call: :play_note),
      (button args,
              row: 5.5, col: 6, text: "Square G4",
              note: :g, octave: 4, type: :square, method_to_call: :play_note),
      (button args,
              row: 6.5, col: 6, text: "Square A5",
              note: :a, octave: 5, type: :square, method_to_call: :play_note),
      (button args,
              row: 7.5, col: 6, text: "Square B5",
              note: :b, octave: 5, type: :square, method_to_call: :play_note),
      (button args,
              row: 8.5, col: 6, text: "Square C5",
              note: :c, octave: 5, type: :square, method_to_call: :play_note),
    ]
  end
  def saw_tooth_wave_note_buttons args
    [
      (button args,
              row: 1.5, col: 8, text: "Saw C4",
              note: :c, octave: 4, type: :saw_tooth, method_to_call: :play_note),
      (button args,
              row: 2.5, col: 8, text: "Saw D4",
              note: :d, octave: 4, type: :saw_tooth, method_to_call: :play_note),
      (button args,
              row: 3.5, col: 8, text: "Saw E4",
              note: :e, octave: 4, type: :saw_tooth, method_to_call: :play_note),
      (button args,
              row: 4.5, col: 8, text: "Saw F4",
              note: :f, octave: 4, type: :saw_tooth, method_to_call: :play_note),
      (button args,
              row: 5.5, col: 8, text: "Saw G4",
              note: :g, octave: 4, type: :saw_tooth, method_to_call: :play_note),
      (button args,
              row: 6.5, col: 8, text: "Saw A5",
              note: :a, octave: 5, type: :saw_tooth, method_to_call: :play_note),
      (button args,
              row: 7.5, col: 8, text: "Saw B5",
              note: :b, octave: 5, type: :saw_tooth, method_to_call: :play_note),
      (button args,
              row: 8.5, col: 8, text: "Saw C5",
              note: :c, octave: 5, type: :saw_tooth, method_to_call: :play_note),
    ]
  end

  def triangle_wave_note_buttons args
    [
      (button args,
              row: 1.5, col: 10, text: "Triangle C4",
              note: :c, octave: 4, type: :triangle, method_to_call: :play_note),
      (button args,
              row: 2.5, col: 10, text: "Triangle D4",
              note: :d, octave: 4, type: :triangle, method_to_call: :play_note),
      (button args,
              row: 3.5, col: 10, text: "Triangle E4",
              note: :e, octave: 4, type: :triangle, method_to_call: :play_note),
      (button args,
              row: 4.5, col: 10, text: "Triangle F4",
              note: :f, octave: 4, type: :triangle, method_to_call: :play_note),
      (button args,
              row: 5.5, col: 10, text: "Triangle G4",
              note: :g, octave: 4, type: :triangle, method_to_call: :play_note),
      (button args,
              row: 6.5, col: 10, text: "Triangle A5",
              note: :a, octave: 5, type: :triangle, method_to_call: :play_note),
      (button args,
              row: 7.5, col: 10, text: "Triangle B5",
              note: :b, octave: 5, type: :triangle, method_to_call: :play_note),
      (button args,
              row: 8.5, col: 10, text: "Triangle C5",
              note: :c, octave: 5, type: :triangle, method_to_call: :play_note),
    ]
  end

  def bell_buttons args
    [
      (button args,
              row: 1.5, col: 4, text: "Bell C4",
              note: :c, octave: 4, type: :bell, method_to_call: :play_note),
      (button args,
              row: 2.5, col: 4, text: "Bell D4",
              note: :d, octave: 4, type: :bell, method_to_call: :play_note),
      (button args,
              row: 3.5, col: 4, text: "Bell E4",
              note: :e, octave: 4, type: :bell, method_to_call: :play_note),
      (button args,
              row: 4.5, col: 4, text: "Bell F4",
              note: :f, octave: 4, type: :bell, method_to_call: :play_note),
      (button args,
              row: 5.5, col: 4, text: "Bell G4",
              note: :g, octave: 4, type: :bell, method_to_call: :play_note),
      (button args,
              row: 6.5, col: 4, text: "Bell A5",
              note: :a, octave: 5, type: :bell, method_to_call: :play_note),
      (button args,
              row: 7.5, col: 4, text: "Bell B5",
              note: :b, octave: 5, type: :bell, method_to_call: :play_note),
      (button args,
              row: 8.5, col: 4, text: "Bell C5",
              note: :c, octave: 5, type: :bell, method_to_call: :play_note),
    ]
  end
end

begin # region: wave generation
  begin # sine wave
    def defaults_sine_wave_for
      { frequency: 440, sample_rate: 48000 }
    end

    def sine_wave_for opts = {}
      opts = defaults_sine_wave_for.merge opts
      frequency   = opts[:frequency]
      sample_rate = opts[:sample_rate]
      period_size = (sample_rate.fdiv frequency).ceil
      period_size.map_with_index do |i|
        Math::sin((2.0 * Math::PI) / (sample_rate.to_f / frequency.to_f) * i)
      end.to_a
    end

    def defaults_queue_sine_wave
      { frequency: 440, duration: 60, gain: 1.0, fade_out: false, queue_in: 0 }
    end

    def queue_sine_wave args, opts = {}
      opts        = defaults_queue_sine_wave.merge opts
      frequency   = opts[:frequency]
      sample_rate = 48000

      sine_wave = sine_wave_for frequency: frequency, sample_rate: sample_rate
      args.state.sine_waves[frequency] ||= sine_wave_for frequency: frequency, sample_rate: sample_rate

      proc = lambda do
        generate_audio_data args.state.sine_waves[frequency], sample_rate
      end

      audio_state = new_audio_state args, opts
      audio_state[:input] = [1, sample_rate, proc]
      queue_audio args, audio_state: audio_state, wave: sine_wave
    end
  end

  begin # region: square wave
    def defaults_square_wave_for
      { frequency: 440, sample_rate: 48000 }
    end

    def square_wave_for opts = {}
      opts = defaults_square_wave_for.merge opts
      sine_wave = sine_wave_for opts
      sine_wave.map do |v|
        if v >= 0
          1.0
        else
          -1.0
        end
      end.to_a
    end

    def defaults_queue_square_wave
      { frequency: 440, duration: 60, gain: 0.3, fade_out: false, queue_in: 0 }
    end

    def queue_square_wave args, opts = {}
      opts        = defaults_queue_square_wave.merge opts
      frequency   = opts[:frequency]
      sample_rate = 48000

      square_wave = square_wave_for frequency: frequency, sample_rate: sample_rate
      args.state.square_waves[frequency] ||= square_wave_for frequency: frequency, sample_rate: sample_rate

      proc = lambda do
        generate_audio_data args.state.square_waves[frequency], sample_rate
      end

      audio_state = new_audio_state args, opts
      audio_state[:input] = [1, sample_rate, proc]
      queue_audio args, audio_state: audio_state, wave: square_wave
    end
  end

  begin # region: saw tooth wave
    def defaults_saw_tooth_wave_for
      { frequency: 440, sample_rate: 48000 }
    end

    def saw_tooth_wave_for opts = {}
      opts = defaults_saw_tooth_wave_for.merge opts
      sine_wave = sine_wave_for opts
      period_size = sine_wave.length
      sine_wave.map_with_index do |v, i|
        (((i % period_size).fdiv period_size) * 2) - 1
      end
    end

    def defaults_queue_saw_tooth_wave
      { frequency: 440, duration: 60, gain: 0.3, fade_out: false, queue_in: 0 }
    end

    def queue_saw_tooth_wave args, opts = {}
      opts        = defaults_queue_saw_tooth_wave.merge opts
      frequency   = opts[:frequency]
      sample_rate = 48000

      saw_tooth_wave = saw_tooth_wave_for frequency: frequency, sample_rate: sample_rate
      args.state.saw_tooth_waves[frequency] ||= saw_tooth_wave_for frequency: frequency, sample_rate: sample_rate

      proc = lambda do
        generate_audio_data args.state.saw_tooth_waves[frequency], sample_rate
      end

      audio_state = new_audio_state args, opts
      audio_state[:input] = [1, sample_rate, proc]
      queue_audio args, audio_state: audio_state, wave: saw_tooth_wave
    end
  end

  begin # region: triangle wave
    def defaults_triangle_wave_for
      { frequency: 440, sample_rate: 48000 }
    end

    def triangle_wave_for opts = {}
      opts = defaults_saw_tooth_wave_for.merge opts
      sine_wave = sine_wave_for opts
      period_size = sine_wave.length
      sine_wave.map_with_index do |v, i|
        ratio = (i.fdiv period_size)
        if ratio <= 0.5
          (ratio * 4) - 1
        else
          ratio -= 0.5
          1 - (ratio * 4)
        end
      end
    end

    def defaults_queue_triangle_wave
      { frequency: 440, duration: 60, gain: 1.0, fade_out: false, queue_in: 0 }
    end

    def queue_triangle_wave args, opts = {}
      opts        = defaults_queue_triangle_wave.merge opts
      frequency   = opts[:frequency]
      sample_rate = 48000

      triangle_wave = triangle_wave_for frequency: frequency, sample_rate: sample_rate
      args.state.triangle_waves[frequency] ||= triangle_wave_for frequency: frequency, sample_rate: sample_rate

      proc = lambda do
        generate_audio_data args.state.triangle_waves[frequency], sample_rate
      end

      audio_state = new_audio_state args, opts
      audio_state[:input] = [1, sample_rate, proc]
      queue_audio args, audio_state: audio_state, wave: triangle_wave
    end
  end

  begin # region: bell
    def defaults_queue_bell
      { frequency: 440, duration: 1.seconds, queue_in: 0 }
    end

    def queue_bell args, opts = {}
      (bell_to_sine_waves (defaults_queue_bell.merge opts)).each { |b| queue_sine_wave args, b }
    end

    def bell_harmonics
      [
        { frequency_ratio: 0.5, duration_ratio: 1.00 },
        { frequency_ratio: 1.0, duration_ratio: 0.80 },
        { frequency_ratio: 2.0, duration_ratio: 0.60 },
        { frequency_ratio: 3.0, duration_ratio: 0.40 },
        { frequency_ratio: 4.2, duration_ratio: 0.25 },
        { frequency_ratio: 5.4, duration_ratio: 0.20 },
        { frequency_ratio: 6.8, duration_ratio: 0.15 }
      ]
    end

    def defaults_bell_to_sine_waves
      { frequency: 440, duration: 1.seconds, queue_in: 0 }
    end

    def bell_to_sine_waves opts = {}
      opts = defaults_bell_to_sine_waves.merge opts
      bell_harmonics.map do |b|
        {
          frequency: opts[:frequency] * b[:frequency_ratio],
          duration:  opts[:duration] * b[:duration_ratio],
          queue_in:  opts[:queue_in],
          gain:      (1.fdiv bell_harmonics.length),
          fade_out:  true
        }
      end
    end
  end

  begin # audio entity construction
    def generate_audio_data sine_wave, sample_rate
      sample_size = (sample_rate.fdiv (1000.fdiv 60)).ceil
      copy_count  = (sample_size.fdiv sine_wave.length).ceil
      sine_wave * copy_count
    end

    def defaults_new_audio_state
      { frequency: 440, duration: 60, gain: 1.0, fade_out: false, queue_in: 0 }
    end

    def new_audio_state args, opts = {}
      opts        = defaults_new_audio_state.merge opts
      decay_rate  = 0
      decay_rate  = 1.fdiv(opts[:duration]) * opts[:gain] if opts[:fade_out]
      frequency   = opts[:frequency]
      sample_rate = 48000

      {
        id:               (new_id! args),
        frequency:        frequency,
        sample_rate:      48000,
        stop_at:          args.tick_count + opts[:queue_in] + opts[:duration],
        gain:             opts[:gain].to_f,
        queue_at:         args.state.tick_count + opts[:queue_in],
        decay_rate:       decay_rate,
        pitch:            1.0,
        looping:          true,
        paused:           false
      }
    end

    def queue_audio args, opts = {}
      graph_wave args, opts[:wave], opts[:audio_state][:frequency]
      args.state.audio_queue << opts[:audio_state]
    end

    def new_id! args
      args.state.audio_id ||= 0
      args.state.audio_id  += 1
    end

    def graph_wave args, wave, frequency
      if args.state.tick_count != args.state.graphed_at
        args.outputs.static_lines.clear
        args.outputs.static_sprites.clear
      end

      wave = wave

      r, g, b = frequency.to_i % 85,
                frequency.to_i % 170,
                frequency.to_i % 255

      starting_rect = args.layout.rect(row: 5, col: 13)
      x_scale    = 10
      y_scale    = 100
      max_points = 25

      points = wave
      if wave.length > max_points
        resolution = wave.length.idiv max_points
        points = wave.find_all.with_index { |y, i| (i % resolution == 0) }
      end

      args.outputs.static_lines << points.map_with_index do |y, x|
        next_y = points[x + 1]

        if next_y
          {
            x:  starting_rect.x + (x * x_scale),
            y:  starting_rect.y + starting_rect.h.half + y_scale * y,
            x2: starting_rect.x + ((x + 1) * x_scale),
            y2: starting_rect.y + starting_rect.h.half + y_scale * next_y,
            r:  r,
            g:  g,
            b:  b
          }
        end
      end

      args.outputs.static_sprites << points.map_with_index do |y, x|
        {
          x:  (starting_rect.x + (x * x_scale)) - 2,
          y:  (starting_rect.y + starting_rect.h.half + y_scale * y) - 2,
          w:  4,
          h:  4,
          path: 'sprites/square-white.png',
          r: r,
          g: g,
          b: b
        }
      end

      args.state.graphed_at = args.state.tick_count
    end
  end

  begin # region: musical note mapping
    def defaults_frequency_for
      { note: :a, octave: 5, sharp:  false, flat:   false }
    end

    def frequency_for opts = {}
      opts = defaults_frequency_for.merge opts
      octave_offset_multiplier  = opts[:octave] - 5
      note = note_frequencies_octave_5[opts[:note]]
      if octave_offset_multiplier < 0
        note = note * 1 / (octave_offset_multiplier.abs + 1)
      elsif octave_offset_multiplier > 0
        note = note * (octave_offset_multiplier.abs + 1) / 1
      end
      note
    end

    def note_frequencies_octave_5
      {
        a: 440.0,
        a_sharp: 466.16, b_flat: 466.16,
        b: 493.88,
        c: 523.25,
        c_sharp: 554.37, d_flat: 587.33,
        d: 587.33,
        d_sharp: 622.25, e_flat: 659.25,
        e: 659.25,
        f: 698.25,
        f_sharp: 739.99, g_flat: 739.99,
        g: 783.99,
        g_sharp: 830.61, a_flat: 830.61
      }
    end
  end
end

$gtk.reset

    Advanced Rendering link

    Labels With Wrapped Text - main.rb link

    # ./samples/07_advanced_rendering/00_labels_with_wrapped_text/app/main.rb
def tick args
  # defaults
  args.state.scroll_location  ||= 0
  args.state.textbox.messages ||= []
  args.state.textbox.scroll   ||= 0

  # render
  args.outputs.background_color = [0, 0, 0, 255]
  render_messages args
  render_instructions args

  # inputs
  if args.inputs.keyboard.key_down.one
    queue_message args, "Hello there neighbour! my name is mark, how is your day today?"
  end

  if args.inputs.keyboard.key_down.two
    queue_message args, "I'm doing great sir, actually I'm having a picnic today"
  end

  if args.inputs.keyboard.key_down.three
    queue_message args, "Well that sounds wonderful!"
  end

  if args.inputs.keyboard.key_down.home
    args.state.scroll_location = 1
  end

  if args.inputs.keyboard.key_down.delete
    clear_message_queue args
  end
end

def queue_message args, msg
  args.state.textbox.messages.concat msg.wrapped_lines 50
end

def clear_message_queue args
  args.state.textbox.messages = nil
  args.state.textbox.scroll = 0
end

def render_messages args
  args.outputs[:textbox].transient!
  args.outputs[:textbox].w = 400
  args.outputs[:textbox].h = 720

  args.outputs.primitives << args.state.textbox.messages.each_with_index.map do |s, idx|
    {
      x: 0,
      y: 20 * (args.state.textbox.messages.size - idx) + args.state.textbox.scroll * 20,
      text: s,
      size_enum: -3,
      alignment_enum: 0,
      r: 255, g:255, b: 255, a: 255
    }
  end

  args.outputs[:textbox].labels << args.state.textbox.messages.each_with_index.map do |s, idx|
    {
      x: 0,
      y: 20 * (args.state.textbox.messages.size - idx) + args.state.textbox.scroll * 20,
      text: s,
      size_enum: -3,
      alignment_enum: 0,
      r: 255, g:255, b: 255, a: 255
    }
  end

  args.outputs[:textbox].borders << [0, 0, args.outputs[:textbox].w, 720]

  args.state.textbox.scroll += args.inputs.mouse.wheel.y unless args.inputs.mouse.wheel.nil?

  if args.state.scroll_location > 0
    args.state.textbox.scroll = 0
    args.state.scroll_location = 0
  end

  args.outputs.sprites << [900, 0, args.outputs[:textbox].w, 720, :textbox]
end

def render_instructions args
  args.outputs.labels << [30,
                          30.from_top,
                          "press 1, 2, 3 to display messages, MOUSE WHEEL to scroll, HOME to go to top, BACKSPACE to delete.",
                          0, 255, 255]

  args.outputs.primitives << [0, 55.from_top, 1280, 30, :pixel, 0, 255, 0, 0, 0].sprite
end

    Rotating Label - main.rb link

    # ./samples/07_advanced_rendering/00_rotating_label/app/main.rb
def tick args
  # set the render target width and height to match the label
  args.outputs[:scene].transient!
  args.outputs[:scene].w = 220
  args.outputs[:scene].h = 30


  # make the background transparent
  args.outputs[:scene].background_color = [255, 255, 255, 0]

  # set the blendmode of the label to 0 (no blending)
  # center it inside of the scene
  # set the vertical_alignment_enum to 1 (center)
  args.outputs[:scene].labels  << { x: 0,
                                    y: 15,
                                    text: "label in render target",
                                    blendmode_enum: 0,
                                    vertical_alignment_enum: 1 }

  # add a border to the render target
  args.outputs[:scene].borders << { x: 0,
                                    y: 0,
                                    w: args.outputs[:scene].w,
                                    h: args.outputs[:scene].h }

  # add the rendertarget to the main output as a sprite
  args.outputs.sprites << { x: 640 - args.outputs[:scene].w.half,
                            y: 360 - args.outputs[:scene].h.half,
                            w: args.outputs[:scene].w,
                            h: args.outputs[:scene].h,
                            angle: args.state.tick_count,
                            path: :scene }
end

    Render Targets Clip Area - main.rb link

    # ./samples/07_advanced_rendering/01_render_targets_clip_area/app/main.rb
def tick args
  # define your state
  args.state.player ||= { x: 0, y: 0, w: 300, h: 300, path: "sprites/square/blue.png" }

  # controller input for player
  args.state.player.x += args.inputs.left_right * 5
  args.state.player.y += args.inputs.up_down * 5

  # create a render target that holds the
  # full view that you want to render

  # make the background transparent
  args.outputs[:clipped_area].background_color = [0, 0, 0, 0]

  # set the w/h to match the screen
  args.outputs[:clipped_area].w = 1280
  args.outputs[:clipped_area].h = 720

  # mark it as transient so that the render target
  # isn't cached (since we are going to be changing it every frame)
  args.outputs[:clipped_area].transient!

  # render the player in the render target
  args.outputs[:clipped_area].sprites << args.state.player

  # render the player and clip area as borders to
  # keep track of where everything is at regardless of clip mode
  args.outputs.borders << args.state.player
  args.outputs.borders << { x: 540, y: 460, w: 200, h: 200 }

  # render the render target, but only the clipped area
  args.outputs.sprites << {
    # where to render the render target
    x: 540,
    y: 460,
    w: 200,
    h: 200,
    # what part of the render target to render
    source_x: 540,
    source_y: 460,
    source_w: 200,
    source_h: 200,
    # path of render target to render
    path: :clipped_area
  }

  # mini map
  args.outputs.borders << { x: 1280 - 160, y: 0, w: 160, h: 90 }
  args.outputs.sprites << { x: 1280 - 160, y: 0, w: 160, h: 90, path: :clipped_area }
end

$gtk.reset

    Render Targets Combining Sprites - main.rb link

    # ./samples/07_advanced_rendering/01_render_targets_combining_sprites/app/main.rb
# sample app shows how to use a render target to
# create a combined sprite
def tick args
  create_combined_sprite args

  # render the combined sprite
  # using its name :two_squares
  # have it move across the screen and rotate
  args.outputs.sprites << { x: args.state.tick_count % 1280,
                            y: 0,
                            w: 80,
                            h: 80,
                            angle: args.state.tick_count,
                            path: :two_squares }
end

def create_combined_sprite args
  # NOTE: you can have the construction of the combined
  #       sprite to happen every tick or only once (if the
  #       combined sprite never changes).
  #
  # if the combined sprite never changes, comment out the line
  # below to only construct it on the first frame and then
  # use the cached texture
  # return if args.state.tick_count != 0 # <---- guard clause to only construct on first frame and cache

  # define the dimensions of the combined sprite
  # the name of the combined sprite is :two_squares
  args.outputs[:two_squares].transient!
  args.outputs[:two_squares].w = 80
  args.outputs[:two_squares].h = 80

  # put a blue sprite within the combined sprite
  # who's width is "thin"
  args.outputs[:two_squares].sprites << {
    x: 40 - 10,
    y: 0,
    w: 20,
    h: 80,
    path: 'sprites/square/blue.png'
  }

  # put a red sprite within the combined sprite
  # who's height is "thin"
  args.outputs[:two_squares].sprites << {
    x: 0,
    y: 40 - 10,
    w: 80,
    h: 20,
    path: 'sprites/square/red.png'
  }
end

    Simple Render Targets - main.rb link

    # ./samples/07_advanced_rendering/01_simple_render_targets/app/main.rb
def tick args
  # args.outputs.render_targets are really really powerful.
  # They essentially allow you to create a sprite programmatically and cache the result.

  # Create a render_target of a :block and a :gradient on tick zero.
  if args.state.tick_count == 0
    args.render_target(:block).solids << [0, 0, 1280, 100]

    # The gradient is actually just a collection of black solids with increasing
    # opacities.
    args.render_target(:gradient).solids << 90.map_with_index do |x|
      50.map_with_index do |y|
        [x * 15, y * 15, 15, 15, 0, 0, 0, (x * 3).fdiv(255) * 255]
      end
    end
  end

  # Take the :block render_target and present it horizontally centered.
  # Use a subsection of the render_targetd specified by source_x,
  # source_y, source_w, source_h.
  args.outputs.sprites << { x: 0,
                            y: 310,
                            w: 1280,
                            h: 100,
                            path: :block,
                            source_x: 0,
                            source_y: 0,
                            source_w: 1280,
                            source_h: 100 }

  # After rendering :block, render gradient on top of :block.
  args.outputs.sprites << [0, 0, 1280, 720, :gradient]

  args.outputs.labels  << [1270, 710, args.gtk.current_framerate, 0, 2, 255, 255, 255]
  tick_instructions args, "Sample app shows how to use render_targets (programmatically create cached sprites)."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

$gtk.reset

    Coordinate Systems And Render Targets - main.rb link

    # ./samples/07_advanced_rendering/02_coordinate_systems_and_render_targets/app/main.rb
def tick args
  # every 4.5 seconds, swap between origin_bottom_left and origin_center
  args.state.origin_state ||= :bottom_left

  if args.state.tick_count.zmod? 270
    args.state.origin_state = if args.state.origin_state == :bottom_left
                                :center
                              else
                                :bottom_left
                              end
  end

  if args.state.origin_state == :bottom_left
    tick_origin_bottom_left args
  else
    tick_origin_center args
  end
end

def tick_origin_center args
  # set the coordinate system to origin_center
  args.grid.origin_center!
  args.outputs.labels <<  { x: 0, y: 100, text: "args.grid.origin_center! with sprite inside of a render target, centered at 0, 0", vertical_alignment_enum: 1, alignment_enum: 1 }

  # create a render target with a sprint in the center assuming the origin is center screen
  args.outputs[:scene].transient!
  args.outputs[:scene].sprites << { x: -50, y: -50, w: 100, h: 100, path: 'sprites/square/blue.png' }
  args.outputs.sprites << { x: -640, y: -360, w: 1280, h: 720, path: :scene }
end

def tick_origin_bottom_left args
  args.grid.origin_bottom_left!
  args.outputs.labels <<  { x: 640, y: 360 + 100, text: "args.grid.origin_bottom_left! with sprite inside of a render target, centered at 640, 360", vertical_alignment_enum: 1, alignment_enum: 1 }

  # create a render target with a sprint in the center assuming the origin is bottom left
  args.outputs[:scene].transient!
  args.outputs[:scene].sprites << { x: 640 - 50, y: 360 - 50, w: 100, h: 100, path: 'sprites/square/blue.png' }
  args.outputs.sprites << { x: 0, y: 0, w: 1280, h: 720, path: :scene }
end

    Render Targets Repeating Texture - main.rb link

    # ./samples/07_advanced_rendering/02_render_targets_repeating_texture/app/main.rb
# Sample app shows how to leverage render targets to create a repeating
# texture given a source sprite.
def tick args
  args.outputs.sprites << repeating_texture(args,
                                            x: 640,
                                            y: 360,
                                            w: 1280,
                                            h: 720,
                                            anchor_x: 0.5,
                                            anchor_y: 0.5,
                                            path: 'sprites/square/blue.png')
end

def repeating_texture args, x:, y:, w:, h:, path:, anchor_x: 0, anchor_y: 0
  # create an area to store state for function
  args.state.repeating_texture_lookup ||= {}

  # create a unique name for the repeating texture
  rt_name = "#{path.hash}-#{w}-#{h}"

  # if the repeating texture has not been created yet, create it
  if args.state.repeating_texture_lookup[rt_name]
    return { x: x,
             y: y,
             w: w,
             h: h,
             anchor_x: anchor_x,
             anchor_y: anchor_y,
             path: rt_name }
  end

  # create a render target to store the repeating texture
  args.outputs[rt_name].w = w
  args.outputs[rt_name].h = h

  # calculate the sprite box for the repeating texture
  sprite_w, sprite_h = args.gtk.calcspritebox path

  # calculate the number of rows and columns needed to fill the repeating texture
  rows = h.idiv(sprite_h) + 1
  cols = w.idiv(sprite_w) + 1

  # generate the repeating texture using a render target
  # this only needs to be done once and will be cached
  args.outputs[rt_name].sprites << rows.map do |r|
                                     cols.map do |c|
                                       { x: sprite_w * c,
                                         y:  h - sprite_h * (r + 1),
                                         w: sprite_w,
                                         h: sprite_h,
                                         path: path }
                                     end
                                   end

  # store a flag in state denoting that the repeating
  # texture has been generated
  args.state.repeating_texture_lookup[rt_name] = true

  # return the repeating texture
  repeating_texture args, x: x, y: y, w: w, h: h, path: path
end

$gtk.reset

    Render Targets Thick Lines - main.rb link

    # ./samples/07_advanced_rendering/02_render_targets_thick_lines/app/main.rb
# Sample app shows how you can use render targets to create arbitrary shapes like a thicker line
def tick args
  args.state.line_cache ||= {}
  args.outputs.primitives << thick_line(args,
                                        args.state.line_cache,
                                        x: 0, y: 0, x2: 640, y2: 360, thickness: 3).merge(r: 0, g: 0, b: 0)
end

def thick_line args, cache, line
  line_length = Math.sqrt((line.x2 - line.x)**2 + (line.y2 - line.y)**2)
  name = "line-sprite-#{line_length}-#{line.thickness}"
  cached_line = cache[name]
  line_angle = Math.atan2(line.y2 - line.y1, line.x2 - line.x1) * 180 / Math::PI
  if cached_line
    perpendicular_angle = (line_angle + 90) % 360
    return cached_line.sprite.merge(x: line.x - perpendicular_angle.vector_x * (line.thickness / 2),
                                    y: line.y - perpendicular_angle.vector_y * (line.thickness / 2),
                                    angle: line_angle)
  end

  cache[name] = {
    line: line,
    thickness: line.thickness,
    sprite: {
      w: line_length,
      h: line.thickness,
      path: name,
      angle_anchor_x: 0,
      angle_anchor_y: 0
    }
  }

  args.outputs[name].w = line_length
  args.outputs[name].h = line.thickness
  args.outputs[name].solids << { x: 0, y: 0, w: line_length, h: line.thickness, r: 255, g: 255, b: 255 }
  return thick_line args, cache, line
end

    Render Targets With Tile Manipulation - main.rb link

    # ./samples/07_advanced_rendering/02_render_targets_with_tile_manipulation/app/main.rb
# This sample is meant to show you how to do that dripping transition thing
#  at the start of the original Doom. Most of this file is here to animate
#  a scene to wipe away; the actual wipe effect is in the last 20 lines or
#  so.

$gtk.reset   # reset all game state if reloaded.

def circle_of_blocks pass, xoffset, yoffset, angleoffset, blocksize, distance
  numblocks = 10

  for i in 1..numblocks do
    angle = ((360 / numblocks) * i) + angleoffset
    radians = angle * (Math::PI / 180)
    x = (xoffset + (distance * Math.cos(radians))).round
    y = (yoffset + (distance * Math.sin(radians))).round
    pass.solids << [ x, y, blocksize, blocksize, 255, 255, 0 ]
  end
end

def draw_scene args, pass
  pass.solids << [0, 360, 1280, 360, 0, 0, 200]
  pass.solids << [0, 0, 1280, 360, 0, 127, 0]

  blocksize = 100
  angleoffset = args.state.tick_count * 2.5
  centerx = (1280 - blocksize) / 2
  centery = (720 - blocksize) / 2

  circle_of_blocks pass, centerx, centery, angleoffset, blocksize * 2, 500
  circle_of_blocks pass, centerx, centery, angleoffset, blocksize, 325
  circle_of_blocks pass, centerx, centery, angleoffset, blocksize / 2, 200
  circle_of_blocks pass, centerx, centery, angleoffset, blocksize / 4, 100
end

def tick args
  segments = 160

  # On the first tick, initialize some stuff.
  if !args.state.yoffsets
    args.state.baseyoff = 0
    args.state.yoffsets = []
    for i in 0..segments do
      args.state.yoffsets << rand * 100
    end
  end

  # Just draw some random stuff for a few seconds.
  args.state.static_debounce ||= 60 * 2.5
  if args.state.static_debounce > 0
    last_frame = args.state.static_debounce == 1
    target = last_frame ? args.render_target(:last_frame) : args.outputs
    draw_scene args, target
    args.state.static_debounce -= 1
    return unless last_frame
  end

  # build up the wipe...

  # this is the thing we're wiping to.
  args.outputs.sprites << [ 0, 0, 1280, 720, 'dragonruby.png' ]

  return if (args.state.baseyoff > (1280 + 100))  # stop when done sliding

  segmentw = 1280 / segments

  x = 0
  for i in 0..segments do
    yoffset = 0
    if args.state.yoffsets[i] < args.state.baseyoff
      yoffset = args.state.baseyoff - args.state.yoffsets[i]
    end

    # (720 - yoffset) flips the coordinate system, (- 720) adjusts for the height of the segment.
    args.outputs.sprites << [ x, (720 - yoffset) - 720, segmentw, 720, 'last_frame', 0, 255, 255, 255, 255, x, 0, segmentw, 720 ]
    x += segmentw
  end

  args.state.baseyoff += 4

  tick_instructions args, "Sample app shows an advanced usage of render_target."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Render Target Viewports - main.rb link

    # ./samples/07_advanced_rendering/03_render_target_viewports/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
   For example, if we want to create a new button, we would declare it as a new entity and
   then define its properties. (Remember, you can use state to define ANY property and it will
   be retained across frames.)

   If you have a solar system and you're creating args.state.sun and setting its image path to an
   image in the sprites folder, you would do the following:
   (See samples/99_sample_nddnug_workshop for more details.)

   args.state.sun ||= args.state.new_entity(:sun) do |s|
   s.path = 'sprites/sun.png'
   end

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

   For example, if we have a variable
   name = "Ruby"
   then the line
   puts "How are you, #{name}?"
   would print "How are you, Ruby?" to the console.
   (Remember, string interpolation only works with double quotes!)

 - Ternary operator (?): Similar to if statement; first evalulates whether a statement is
   true or false, and then executes a command depending on that result.
   For example, if we had a variable
   grade = 75
   and used the ternary operator in the command
   pass_or_fail = grade > 65 ? "pass" : "fail"
   then the value of pass_or_fail would be "pass" since grade's value was greater than 65.

 Reminders:

 - args.grid.(left|right|top|bottom): Pixel value for the boundaries of the virtual
   720 p screen (Dragon Ruby Game Toolkits's virtual resolution is always 1280x720).

 - Numeric#shift_(left|right|up|down): Shifts the Numeric in the correct direction
   by adding or subracting.

 - ARRAY#inside_rect?: An array with at least two values is considered a point. An array
   with at least four values is considered a rect. The inside_rect? function returns true
   or false depending on if the point is inside the rect.

 - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.

 - args.inputs.mouse.click: This property will be set if the mouse was clicked.
   For more information about the mouse, go to mygame/documentation/07-mouse.md.

 - args.inputs.keyboard.key_up.KEY: The value of the properties will be set
   to the frame  that the key_up event occurred (the frame correlates
   to args.state.tick_count).
   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.

 - args.state.labels:
   The parameters for a label are
   1. the position (x, y)
   2. the text
   3. the size
   4. the alignment
   5. the color (red, green, and blue saturations)
   6. the alpha (or transparency)
   For more information about labels, go to mygame/documentation/02-labels.md.

 - args.state.lines:
   The parameters for a line are
   1. the starting position (x, y)
   2. the ending position (x2, y2)
   3. the color (red, green, and blue saturations)
   4. the alpha (or transparency)
   For more information about lines, go to mygame/documentation/04-lines.md.

 - args.state.solids (and args.state.borders):
   The parameters for a solid (or border) are
   1. the position (x, y)
   2. the width (w)
   3. the height (h)
   4. the color (r, g, b)
   5. the alpha (or transparency)
   For more information about solids and borders, go to mygame/documentation/03-solids-and-borders.md.

 - args.state.sprites:
   The parameters for a sprite are
   1. the position (x, y)
   2. the width (w)
   3. the height (h)
   4. the image path
   5. the angle
   6. the alpha (or transparency)
   For more information about sprites, go to mygame/documentation/05-sprites.md.
=end

# This sample app shows different objects that can be used when making games, such as labels,
# lines, sprites, solids, buttons, etc. Each demo section shows how these objects can be used.

# Also note that state.tick_count refers to the passage of time, or current frame.

class TechDemo
  attr_accessor :inputs, :state, :outputs, :grid, :args

  # Calls all methods necessary for the app to run properly.
  def tick
    labels_tech_demo
    lines_tech_demo
    solids_tech_demo
    borders_tech_demo
    sprites_tech_demo
    keyboards_tech_demo
    controller_tech_demo
    mouse_tech_demo
    point_to_rect_tech_demo
    rect_to_rect_tech_demo
    button_tech_demo
    export_game_state_demo
    window_state_demo
    render_seperators
  end

  # Shows output of different kinds of labels on the screen
  def labels_tech_demo
    outputs.labels << [grid.left.shift_right(5), grid.top.shift_down(5), "This is a label located at the top left."]
    outputs.labels << [grid.left.shift_right(5), grid.bottom.shift_up(30), "This is a label located at the bottom left."]
    outputs.labels << [ 5, 690, "Labels (x, y, text, size, align, r, g, b, a)"]
    outputs.labels << [ 5, 660, "Smaller label.",  -2]
    outputs.labels << [ 5, 630, "Small label.",    -1]
    outputs.labels << [ 5, 600, "Medium label.",    0]
    outputs.labels << [ 5, 570, "Large label.",     1]
    outputs.labels << [ 5, 540, "Larger label.",    2]
    outputs.labels << [300, 660, "Left aligned.",    0, 2]
    outputs.labels << [300, 640, "Center aligned.",  0, 1]
    outputs.labels << [300, 620, "Right aligned.",   0, 0]
    outputs.labels << [175, 595, "Red Label.",       0, 0, 255,   0,   0]
    outputs.labels << [175, 575, "Green Label.",     0, 0,   0, 255,   0]
    outputs.labels << [175, 555, "Blue Label.",      0, 0,   0,   0, 255]
    outputs.labels << [175, 535, "Faded Label.",     0, 0,   0,   0,   0, 128]
  end

  # Shows output of lines on the screen
  def lines_tech_demo
    outputs.labels << [5, 500, "Lines (x, y, x2, y2, r, g, b, a)"]
    outputs.lines  << [5, 450, 100, 450]
    outputs.lines  << [5, 430, 300, 430]
    outputs.lines  << [5, 410, 300, 410, state.tick_count % 255, 0, 0, 255] # red saturation changes
    outputs.lines  << [5, 390 - state.tick_count % 25, 300, 390, 0, 0, 0, 255] # y position changes
    outputs.lines  << [5 + state.tick_count % 200, 360, 300, 360, 0, 0, 0, 255] # x position changes
  end

  # Shows output of different kinds of solids on the screen
  def solids_tech_demo
    outputs.labels << [  5, 350, "Solids (x, y, w, h, r, g, b, a)"]
    outputs.solids << [ 10, 270, 50, 50]
    outputs.solids << [ 70, 270, 50, 50, 0, 0, 0]
    outputs.solids << [130, 270, 50, 50, 255, 0, 0]
    outputs.solids << [190, 270, 50, 50, 255, 0, 0, 128]
    outputs.solids << [250, 270, 50, 50, 0, 0, 0, 128 + state.tick_count % 128] # transparency changes
  end

  # Shows output of different kinds of borders on the screen
  # The parameters for a border are the same as the parameters for a solid
  def borders_tech_demo
    outputs.labels <<  [  5, 260, "Borders (x, y, w, h, r, g, b, a)"]
    outputs.borders << [ 10, 180, 50, 50]
    outputs.borders << [ 70, 180, 50, 50, 0, 0, 0]
    outputs.borders << [130, 180, 50, 50, 255, 0, 0]
    outputs.borders << [190, 180, 50, 50, 255, 0, 0, 128]
    outputs.borders << [250, 180, 50, 50, 0, 0, 0, 128 + state.tick_count % 128] # transparency changes
  end

  # Shows output of different kinds of sprites on the screen
  def sprites_tech_demo
    outputs.labels <<  [   5, 170, "Sprites (x, y, w, h, path, angle, a)"]
    outputs.sprites << [  10, 40, 128, 101, 'dragonruby.png']
    outputs.sprites << [ 150, 40, 128, 101, 'dragonruby.png', state.tick_count % 360] # angle changes
    outputs.sprites << [ 300, 40, 128, 101, 'dragonruby.png', 0, state.tick_count % 255] # transparency changes
  end

  # Holds size, alignment, color (black), and alpha (transparency) parameters
  # Using small_font as a parameter accounts for all remaining parameters
  # so they don't have to be repeatedly typed
  def small_font
    [-2, 0, 0, 0, 0, 255]
  end

  # Sets position of each row
  # Converts given row value to pixels that DragonRuby understands
  def row_to_px row_number

    # Row 0 starts 5 units below the top of the grid.
    # Each row afterward is 20 units lower.
    grid.top.shift_down(5).shift_down(20 * row_number)
  end

  # Uses labels to output current game time (passage of time), and whether or not "h" was pressed
  # If "h" is pressed, the frame is output when the key_up event occurred
  def keyboards_tech_demo
    outputs.labels << [460, row_to_px(0), "Current game time: #{state.tick_count}", small_font]
    outputs.labels << [460, row_to_px(2), "Keyboard input: inputs.keyboard.key_up.h", small_font]
    outputs.labels << [460, row_to_px(3), "Press \"h\" on the keyboard.", small_font]

    if inputs.keyboard.key_up.h # if "h" key_up event occurs
      state.h_pressed_at = state.tick_count # frame it occurred is stored
    end

    # h_pressed_at is initially set to false, and changes once the user presses the "h" key.
    state.h_pressed_at ||= false

    if state.h_pressed_at # if h is pressed (pressed_at has a frame number and is no longer false)
      outputs.labels << [460, row_to_px(4), "\"h\" was pressed at time: #{state.h_pressed_at}", small_font]
    else # otherwise, label says "h" was never pressed
      outputs.labels << [460, row_to_px(4), "\"h\" has never been pressed.", small_font]
    end

    # border around keyboard input demo section
    outputs.borders << [455, row_to_px(5), 360, row_to_px(2).shift_up(5) - row_to_px(5)]
  end

  # Sets definition for a small label
  # Makes it easier to position labels in respect to the position of other labels
  def small_label x, row, message
    [x, row_to_px(row), message, small_font]
  end

  # Uses small labels to show whether the "a" button on the controller is down, held, or up.
  # y value of each small label is set by calling the row_to_px method
  def controller_tech_demo
    x = 460
    outputs.labels << small_label(x, 6, "Controller one input: inputs.controller_one")
    outputs.labels << small_label(x, 7, "Current state of the \"a\" button.")
    outputs.labels << small_label(x, 8, "Check console window for more info.")

    if inputs.controller_one.key_down.a # if "a" is in "down" state
      outputs.labels << small_label(x, 9, "\"a\" button down: #{inputs.controller_one.key_down.a}")
      puts "\"a\" button down at #{inputs.controller_one.key_down.a}" # prints frame the event occurred
    elsif inputs.controller_one.key_held.a # if "a" is held down
      outputs.labels << small_label(x, 9, "\"a\" button held: #{inputs.controller_one.key_held.a}")
    elsif inputs.controller_one.key_up.a # if "a" is in up state
      outputs.labels << small_label(x, 9, "\"a\" button up: #{inputs.controller_one.key_up.a}")
      puts "\"a\" key up at #{inputs.controller_one.key_up.a}"
    else # if no event has occurred
      outputs.labels << small_label(x, 9, "\"a\" button state is nil.")
    end

    # border around controller input demo section
    outputs.borders << [455, row_to_px(10), 360, row_to_px(6).shift_up(5) - row_to_px(10)]
  end

  # Outputs when the mouse was clicked, as well as the coordinates on the screen
  # of where the click occurred
  def mouse_tech_demo
    x = 460

    outputs.labels << small_label(x, 11, "Mouse input: inputs.mouse")

    if inputs.mouse.click # if click has a value and is not nil
      state.last_mouse_click = inputs.mouse.click # coordinates of click are stored
    end

    if state.last_mouse_click # if mouse is clicked (has coordinates as value)
      # outputs the time (frame) the click occurred, as well as how many frames have passed since the event
      outputs.labels << small_label(x, 12, "Mouse click happened at: #{state.last_mouse_click.created_at}, #{state.last_mouse_click.created_at_elapsed}")
      # outputs coordinates of click
      outputs.labels << small_label(x, 13, "Mouse click location: #{state.last_mouse_click.point.x}, #{state.last_mouse_click.point.y}")
    else # otherwise if the mouse has not been clicked
      outputs.labels << small_label(x, 12, "Mouse click has not occurred yet.")
      outputs.labels << small_label(x, 13, "Please click mouse.")
    end
  end

  # Outputs whether a mouse click occurred inside or outside of a box
  def point_to_rect_tech_demo
    x = 460

    outputs.labels << small_label(x, 15, "Click inside the blue box maybe ---->")

    box = [765, 370, 50, 50, 0, 0, 170] # blue box
    outputs.borders << box

    if state.last_mouse_click # if the mouse was clicked
      if state.last_mouse_click.point.inside_rect? box # if mouse clicked inside box
        outputs.labels << small_label(x, 16, "Mouse click happened inside the box.")
      else # otherwise, if mouse was clicked outside the box
        outputs.labels << small_label(x, 16, "Mouse click happened outside the box.")
      end
    else # otherwise, if was not clicked at all
      outputs.labels << small_label(x, 16, "Mouse click has not occurred yet.") # output if the mouse was not clicked
    end

    # border around mouse input demo section
    outputs.borders << [455, row_to_px(14), 360, row_to_px(11).shift_up(5) - row_to_px(14)]
  end

  # Outputs a red box onto the screen. A mouse click from the user inside of the red box will output
  # a smaller box. If two small boxes are inside of the red box, it will be determined whether or not
  # they intersect.
  def rect_to_rect_tech_demo
    x = 460

    outputs.labels << small_label(x, 17.5, "Click inside the red box below.") # label with instructions
    red_box = [460, 250, 355, 90, 170, 0, 0] # definition of the red box
    outputs.borders << red_box # output as a border (not filled in)

    # If the mouse is clicked inside the red box, two collision boxes are created.
    if inputs.mouse.click
      if inputs.mouse.click.point.inside_rect? red_box
        if !state.box_collision_one # if the collision_one box does not yet have a definition
          # Subtracts 25 from the x and y positions of the click point in order to make the click point the center of the box.
          # You can try deleting the subtraction to see how it impacts the box placement.
          state.box_collision_one = [inputs.mouse.click.point.x - 25, inputs.mouse.click.point.y - 25, 50, 50, 180, 0,   0, 180]  # sets definition
        elsif !state.box_collision_two # if collision_two does not yet have a definition
          state.box_collision_two = [inputs.mouse.click.point.x - 25, inputs.mouse.click.point.y - 25, 50, 50,   0, 0, 180, 180] # sets definition
        else
          state.box_collision_one = nil # both boxes are empty
          state.box_collision_two = nil
        end
      end
    end

    # If collision boxes exist, they are output onto screen inside the red box as solids
    if state.box_collision_one
      outputs.solids << state.box_collision_one
    end

    if state.box_collision_two
      outputs.solids << state.box_collision_two
    end

    # Outputs whether or not the two collision boxes intersect.
    if state.box_collision_one && state.box_collision_two # if both collision_boxes are defined (and not nil or empty)
      if state.box_collision_one.intersect_rect? state.box_collision_two # if the two boxes intersect
        outputs.labels << small_label(x, 23.5, 'The boxes intersect.')
      else # otherwise, if the two boxes do not intersect
        outputs.labels << small_label(x, 23.5, 'The boxes do not intersect.')
      end
    else
      outputs.labels << small_label(x, 23.5, '--') # if the two boxes are not defined (are nil or empty), this label is output
    end
  end

  # Creates a button and outputs it onto the screen using labels and borders.
  # If the button is clicked, the color changes to make it look faded.
  def button_tech_demo
    x, y, w, h = 460, 160, 300, 50
    state.button        ||= state.new_entity(:button_with_fade)

    # Adds w.half to x and h.half + 10 to y in order to display the text inside the button's borders.
    state.button.label  ||= [x + w.half, y + h.half + 10, "click me and watch me fade", 0, 1]
    state.button.border ||= [x, y, w, h]

    if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.button.border) # if mouse is clicked, and clicked inside button's border
      state.button.clicked_at = inputs.mouse.click.created_at # stores the time the click occurred
    end

    outputs.labels << state.button.label
    outputs.borders << state.button.border

    if state.button.clicked_at # if button was clicked (variable has a value and is not nil)

      # The appearance of the button changes for 0.25 seconds after the time the button is clicked at.
      # The color changes (rgb is set to 0, 180, 80) and the transparency gradually changes.
      # Change 0.25 to 1.25 and notice that the transparency takes longer to return to normal.
      outputs.solids << [x, y, w, h, 0, 180, 80, 255 * state.button.clicked_at.ease(0.25.seconds, :flip)]
    end
  end

  # Creates a new button by declaring it as a new entity, and sets values.
  def new_button_prefab x, y, message
    w, h = 300, 50
    button        = state.new_entity(:button_with_fade)
    button.label  = [x + w.half, y + h.half + 10, message, 0, 1] # '+ 10' keeps label's text within button's borders
    button.border = [x, y, w, h] # sets border definition
    button
  end

  # If the mouse has been clicked and the click's location is inside of the button's border, that means
  # that the button has been clicked. This method returns a boolean value.
  def button_clicked? button
    inputs.mouse.click && inputs.mouse.click.point.inside_rect?(button.border)
  end

  # Determines if button was clicked, and changes its appearance if it is clicked
  def tick_button_prefab button
    outputs.labels << button.label # outputs button's label and border
    outputs.borders << button.border

    if button_clicked? button # if button is clicked
      button.clicked_at = inputs.mouse.click.created_at # stores the time that the button was clicked
    end

    if button.clicked_at # if clicked_at has a frame value and is not nil
      # button is output; color changes and transparency changes for 0.25 seconds after click occurs
      outputs.solids << [button.border.x, button.border.y, button.border.w, button.border.h,
                         0, 180, 80, 255 * button.clicked_at.ease(0.25.seconds, :flip)] # transparency changes for 0.25 seconds
    end
  end

  # Exports the app's game state if the export button is clicked.
  def export_game_state_demo
    state.export_game_state_button ||= new_button_prefab(460, 100, "click to export app state")
    tick_button_prefab(state.export_game_state_button) # calls method to output button
    if button_clicked? state.export_game_state_button # if the export button is clicked
      args.gtk.export! "Exported from clicking the export button in the tech demo." # the export occurs
    end
  end

  # The mouse and keyboard focus are set to "yes" when the Dragonruby window is the active window.
  def window_state_demo
    m = $gtk.args.inputs.mouse.has_focus ? 'Y' : 'N' # ternary operator (similar to if statement)
    k = $gtk.args.inputs.keyboard.has_focus ? 'Y' : 'N'
    outputs.labels << [460, 20, "mouse focus: #{m}   keyboard focus: #{k}", small_font]
  end

  #Sets values for the horizontal separator (divides demo sections)
  def horizontal_seperator y, x, x2
    [x, y, x2, y, 150, 150, 150]
  end

  #Sets the values for the vertical separator (divides demo sections)
  def vertical_seperator x, y, y2
    [x, y, x, y2, 150, 150, 150]
  end

  # Outputs vertical and horizontal separators onto the screen to separate each demo section.
  def render_seperators
    outputs.lines << horizontal_seperator(505, grid.left, 445)
    outputs.lines << horizontal_seperator(353, grid.left, 445)
    outputs.lines << horizontal_seperator(264, grid.left, 445)
    outputs.lines << horizontal_seperator(174, grid.left, 445)

    outputs.lines << vertical_seperator(445, grid.top, grid.bottom)

    outputs.lines << horizontal_seperator(690, 445, 820)
    outputs.lines << horizontal_seperator(426, 445, 820)

    outputs.lines << vertical_seperator(820, grid.top, grid.bottom)
  end
end

$tech_demo = TechDemo.new

def tick args
  $tech_demo.inputs = args.inputs
  $tech_demo.state = args.state
  $tech_demo.grid = args.grid
  $tech_demo.args = args
  $tech_demo.outputs = args.render_target(:mini_map)
  $tech_demo.outputs.transient = true
  $tech_demo.tick
  args.outputs.labels  << [830, 715, "Render target:", [-2, 0, 0, 0, 0, 255]]
  args.outputs.sprites << [0, 0, 1280, 720, :mini_map]
  args.outputs.sprites << [830, 300, 675, 379, :mini_map]
  tick_instructions args, "Sample app shows all the rendering apis available."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Render Primitive Hierarchies - main.rb link

    # ./samples/07_advanced_rendering/04_render_primitive_hierarchies/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - Nested array: An array whose individual elements are also arrays; useful for
   storing groups of similar data.  Also called multidimensional arrays.

   In this sample app, we see nested arrays being used in object definitions.
   Notice the parameters for solids, listed below. Parameters 1-3 set the
   definition for the rect, and parameter 4 sets the definition of the color.

   Instead of having a solid definition that looks like this,
   [X, Y, W, H, R, G, B]
   we can separate it into two separate array definitions in one, like this
   [[X, Y, W, H], [R, G, B]]
   and both options work fine in defining our solid (or any object).

 - Collections: Lists of data; useful for organizing large amounts of data.
   One element of a collection could be an array (which itself contains many elements).
   For example, a collection that stores two solid objects would look like this:
   [
    [100, 100, 50, 50, 0, 0, 0],
    [100, 150, 50, 50, 255, 255, 255]
   ]
   If this collection was added to args.outputs.solids, two solids would be output
   next to each other, one black and one white.
   Nested arrays can be used in collections, as you will see in this sample app.

 Reminders:

 - args.outputs.solids: An array. The values generate a solid.
   The parameters for a solid are
   1. The position on the screen (x, y)
   2. The width (w)
   3. The height (h)
   4. The color (r, g, b) (if a color is not assigned, the object's default color will be black)
   NOTE: THE PARAMETERS ARE THE SAME FOR BORDERS!

   Here is an example of a (red) border or solid definition:
   [100, 100, 400, 500, 255, 0, 0]
   It will be a solid or border depending on if it is added to args.outputs.solids or args.outputs.borders.
   For more information about solids and borders, go to mygame/documentation/03-solids-and-borders.md.

 - args.outputs.sprites: An array. The values generate a sprite.
   The parameters for sprites are
   1. The position on the screen (x, y)
   2. The width (w)
   3. The height (h)
   4. The image path (p)

   Here is an example of a sprite definition:
   [100, 100, 400, 500, 'sprites/dragonruby.png']
   For more information about sprites, go to mygame/documentation/05-sprites.md.

=end

# This code demonstrates the creation and output of objects like sprites, borders, and solids
# If filled in, they are solids
# If hollow, they are borders
# If images, they are sprites

# Solids are added to args.outputs.solids
# Borders are added to args.outputs.borders
# Sprites are added to args.outputs.sprites

# The tick method runs 60 frames every second.
# Your game is going to happen under this one function.
def tick args
  border_as_solid_and_solid_as_border args
  sprite_as_border_or_solids args
  collection_of_borders_and_solids args
  collection_of_sprites args
end

# Shows a border being output onto the screen as a border and a solid
# Also shows how colors can be set
def border_as_solid_and_solid_as_border args
  border = [0, 0, 50, 50]
  args.outputs.borders << border
  args.outputs.solids  << border

  # Red, green, blue saturations (last three parameters) can be any number between 0 and 255
  border_with_color = [0, 100, 50, 50, 255, 0, 0]
  args.outputs.borders << border_with_color
  args.outputs.solids  << border_with_color

  border_with_nested_color = [0, 200, 50, 50, [0, 255, 0]] # nested color
  args.outputs.borders << border_with_nested_color
  args.outputs.solids  << border_with_nested_color

  border_with_nested_rect = [[0, 300, 50, 50], 0, 0, 255] # nested rect
  args.outputs.borders << border_with_nested_rect
  args.outputs.solids  << border_with_nested_rect

  border_with_nested_color_and_rect = [[0, 400, 50, 50], [255, 0, 255]] # nested rect and color
  args.outputs.borders << border_with_nested_color_and_rect
  args.outputs.solids  << border_with_nested_color_and_rect
end

# Shows a sprite output onto the screen as a sprite, border, and solid
# Demonstrates that all three outputs appear differently on screen
def sprite_as_border_or_solids args
  sprite = [100, 0, 50, 50, 'sprites/ship.png']
  args.outputs.sprites << sprite

  # Sprite_as_border variable has same parameters (excluding position) as above object,
  # but will appear differently on screen because it is added to args.outputs.borders
  sprite_as_border = [100, 100, 50, 50, 'sprites/ship.png']
  args.outputs.borders << sprite_as_border

  # Sprite_as_solid variable has same parameters (excluding position) as above object,
  # but will appear differently on screen because it is added to args.outputs.solids
  sprite_as_solid = [100, 200, 50, 50, 'sprites/ship.png']
  args.outputs.solids << sprite_as_solid
end

# Holds and outputs a collection of borders and a collection of solids
# Collections are created by using arrays to hold parameters of each individual object
def collection_of_borders_and_solids args
  collection_borders = [
    [
      [200,  0, 50, 50],                    # black border
      [200,  100, 50, 50, 255, 0, 0],       # red border
      [200,  200, 50, 50, [0, 255, 0]],     # nested color
    ],
    [[200, 300, 50, 50], 0, 0, 255],        # nested rect
    [[200, 400, 50, 50], [255, 0, 255]]     # nested rect and nested color
  ]

  args.outputs.borders << collection_borders

  collection_solids = [
    [
      [[300, 300, 50, 50], 0, 0, 255],      # nested rect
      [[300, 400, 50, 50], [255, 0, 255]]   # nested rect and nested color
    ],
    [300,  0, 50, 50],
    [300,  100, 50, 50, 255, 0, 0],
    [300,  200, 50, 50, [0, 255, 0]],       # nested color
  ]

  args.outputs.solids << collection_solids
end

# Holds and outputs a collection of sprites by adding it to args.outputs.sprites
# Also outputs a collection with same parameters (excluding position) by adding
# it to args.outputs.solids and another to args.outputs.borders
def collection_of_sprites args
  sprites_collection = [
    [
      [400, 0, 50, 50, 'sprites/ship.png'],
      [400, 100, 50, 50, 'sprites/ship.png'],
    ],
    [400, 200, 50, 50, 'sprites/ship.png']
  ]

  args.outputs.sprites << sprites_collection

  args.outputs.solids << [
    [500, 0, 50, 50, 'sprites/ship.png'],
    [500, 100, 50, 50, 'sprites/ship.png'],
    [[[500, 200, 50, 50, 'sprites/ship.png']]]
  ]

  args.outputs.borders << [
    [
      [600, 0, 50, 50, 'sprites/ship.png'],
      [600, 100, 50, 50, 'sprites/ship.png'],
    ],
    [600, 200, 50, 50, 'sprites/ship.png']
  ]
end

    Render Primitives As Hash - main.rb link

    # ./samples/07_advanced_rendering/05_render_primitives_as_hash/app/main.rb
=begin

 Reminders:

 - Hashes: Collection of unique keys and their corresponding values. The value can be found
   using their keys.

   For example, if we have a "numbers" hash that stores numbers in English as the
   key and numbers in Spanish as the value, we'd have a hash that looks like this...
   numbers = { "one" => "uno", "two" => "dos", "three" => "tres" }
   and on it goes.

   Now if we wanted to find the corresponding value of the "one" key, we could say
   puts numbers["one"]
   which would print "uno" to the console.

 - args.outputs.sprites: An array. The values generate a sprite.
   The parameters are [X, Y, WIDTH, HEIGHT, PATH, ANGLE, ALPHA, RED, GREEN, BLUE]
   For more information about sprites, go to mygame/documentation/05-sprites.md.

 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - args.outputs.solids: An array. The values generate a solid.
   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE, ALPHA]
   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.

 - args.outputs.borders: An array. The values generate a border.
   The parameters are the same as a solid.
   For more information about borders, go to mygame/documentation/03-solids-and-borders.md.

 - args.outputs.lines: An array. The values generate a line.
   The parameters are [X1, Y1, X2, Y2, RED, GREEN, BLUE]
   For more information about labels, go to mygame/documentation/02-labels.md.

=end

# This sample app demonstrates how hashes can be used to output different kinds of objects.

def tick args
  args.state.angle ||= 0 # initializes angle to 0
  args.state.angle  += 1 # increments angle by 1 every frame (60 times a second)

  # Outputs sprite using a hash
  args.outputs.sprites << {
    x: 30,                          # sprite position
    y: 550,
    w: 128,                         # sprite size
    h: 101,
    path: "dragonruby.png",         # image path
    angle: args.state.angle,        # angle
    a: 255,                         # alpha (transparency)
    r: 255,                         # color saturation
    g: 255,
    b: 255,
    tile_x:  0,                     # sprite sub division/tile
    tile_y:  0,
    tile_w: -1,
    tile_h: -1,
    flip_vertically: false,         # don't flip sprite
    flip_horizontally: false,
    angle_anchor_x: 0.5,            # rotation center set to middle
    angle_anchor_y: 0.5
  }

  # Outputs label using a hash
  args.outputs.labels << {
    x:              200,                 # label position
    y:              550,
    text:           "dragonruby",        # label text
    size_enum:      2,
    alignment_enum: 1,
    r:              155,                 # color saturation
    g:              50,
    b:              50,
    a:              255,                 # transparency
    font:           "fonts/manaspc.ttf"  # font style; without mentioned file, label won't output correctly
  }

  # Outputs solid using a hash
  # [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE, ALPHA]
  args.outputs.solids << {
    x: 400,                         # position
    y: 550,
    w: 160,                         # size
    h:  90,
    r: 120,                         # color saturation
    g:  50,
    b:  50,
    a: 255                          # transparency
  }

  # Outputs border using a hash
  # Same parameters as a solid
  args.outputs.borders << {
    x: 600,
    y: 550,
    w: 160,
    h:  90,
    r: 120,
    g:  50,
    b:  50,
    a: 255
  }

  # Outputs line using a hash
  args.outputs.lines << {
    x:  900,                        # starting position
    y:  550,
    x2: 1200,                       # ending position
    y2: 550,
    r:  120,                        # color saturation
    g:   50,
    b:   50,
    a:  255                         # transparency
  }

  # Outputs sprite as a primitive using a hash
  args.outputs.primitives << {
    x: 30,                          # position
    y: 200,
    w: 128,                         # size
    h: 101,
    path: "dragonruby.png",         # image path
    angle: args.state.angle,        # angle
    a: 255,                         # transparency
    r: 255,                         # color saturation
    g: 255,
    b: 255,
    tile_x:  0,                     # sprite sub division/tile
    tile_y:  0,
    tile_w: -1,
    tile_h: -1,
    flip_vertically: false,         # don't flip
    flip_horizontally: false,
    angle_anchor_x: 0.5,            # rotation center set to middle
    angle_anchor_y: 0.5
  }.sprite!

  # Outputs label as primitive using a hash
  args.outputs.primitives << {
    x:         200,                 # position
    y:         200,
    text:      "dragonruby",        # text
    size:      2,
    alignment: 1,
    r:         155,                 # color saturation
    g:         50,
    b:         50,
    a:         255,                 # transparency
    font:      "fonts/manaspc.ttf"  # font style
  }.label!

  # Outputs solid as primitive using a hash
  args.outputs.primitives << {
    x: 400,                         # position
    y: 200,
    w: 160,                         # size
    h:  90,
    r: 120,                         # color saturation
    g:  50,
    b:  50,
    a: 255                          # transparency
  }.solid!

  # Outputs border as primitive using a hash
  # Same parameters as solid
  args.outputs.primitives << {
    x: 600,                         # position
    y: 200,
    w: 160,                         # size
    h:  90,
    r: 120,                         # color saturation
    g:  50,
    b:  50,
    a: 255                          # transparency
  }.border!

  # Outputs line as primitive using a hash
  args.outputs.primitives << {
    x:  900,                        # starting position
    y:  200,
    x2: 1200,                       # ending position
    y2: 200,
    r:  120,                        # color saturation
    g:   50,
    b:   50,
    a:  255                         # transparency
  }.line!
end

    Buttons As Render Targets - main.rb link

    # ./samples/07_advanced_rendering/06_buttons_as_render_targets/app/main.rb
def tick args
  # create a texture/render_target that's composed of a border and a label
  create_button args, :hello_world_button, "Hello World", 500, 50

  # two button primitives using the hello_world_button render_target
  args.state.buttons ||= [
    # one button at the top
    { id: :top_button, x: 640 - 250, y: 80.from_top, w: 500, h: 50, path: :hello_world_button },

    # another button at the buttom, upside down, and flipped horizontally
    { id: :bottom_button, x: 640 - 250, y: 30, w: 500, h: 50, path: :hello_world_button, angle: 180, flip_horizontally: true },
  ]

  # check if a mouse click occurred
  if args.inputs.mouse.click
    # check to see if any of the buttons were intersected
    # and set the selected button if so
    args.state.selected_button = args.state.buttons.find { |b| b.intersect_rect? args.inputs.mouse }
  end

  # render the buttons
  args.outputs.sprites << args.state.buttons

  # if there was a selected button, print it's id
  if args.state.selected_button
    args.outputs.labels << { x: 30, y: 30.from_top, text: "#{args.state.selected_button.id} was clicked." }
  end
end

def create_button args, id, text, w, h
  # render_targets only need to be created once, we use the the id to determine if the texture
  # has already been created
  args.state.created_buttons ||= {}
  return if args.state.created_buttons[id]

  # if the render_target hasn't been created, then generate it and store it in the created_buttons cache
  args.state.created_buttons[id] = { created_at: args.state.tick_count, id: id, w: w, h: h, text: text }

  # define the w/h of the texture
  args.outputs[id].w = w
  args.outputs[id].h = h

  # create a border
  args.outputs[id].borders << { x: 0, y: 0, w: w, h: h }

  # create a label centered vertically and horizontally within the texture
  args.outputs[id].labels << { x: w / 2, y: h / 2, text: text, vertical_alignment_enum: 1, alignment_enum: 1 }
end

    Pixel Arrays - main.rb link

    # ./samples/07_advanced_rendering/06_pixel_arrays/app/main.rb
def tick args
  args.state.posinc ||= 1
  args.state.pos ||= 0
  args.state.rotation ||= 0

  dimension = 10  # keep it small and let the GPU scale it when rendering the sprite.

  # Set up our "scanner" pixel array and fill it with black pixels.
  args.pixel_array(:scanner).width = dimension
  args.pixel_array(:scanner).height = dimension
  args.pixel_array(:scanner).pixels.fill(0xFF000000, 0, dimension * dimension)  # black, full alpha

  # Draw a green line that bounces up and down the sprite.
  args.pixel_array(:scanner).pixels.fill(0xFF00FF00, dimension * args.state.pos, dimension)  # green, full alpha

  # Adjust position for next frame.
  args.state.pos += args.state.posinc
  if args.state.posinc > 0 && args.state.pos >= dimension
    args.state.posinc = -1
    args.state.pos = dimension - 1
  elsif args.state.posinc < 0 && args.state.pos < 0
    args.state.posinc = 1
    args.state.pos = 1
  end

  # New/changed pixel arrays get uploaded to the GPU before we render
  #  anything. At that point, they can be scaled, rotated, and otherwise
  #  used like any other sprite.
  w = 100
  h = 100
  x = (1280 - w) / 2
  y = (720 - h) / 2
  args.outputs.background_color = [64, 0, 128]
  args.outputs.primitives << [x, y, w, h, :scanner, args.state.rotation].sprite
  args.state.rotation += 1

  args.outputs.primitives << args.gtk.current_framerate_primitives
end


$gtk.reset

    Pixel Arrays From File - main.rb link

    # ./samples/07_advanced_rendering/06_pixel_arrays_from_file/app/main.rb
def tick args
  args.state.rotation ||= 0

  # on load, get pixels from png and load it into a pixel array
  if args.state.tick_count == 0
    pixel_array = args.gtk.get_pixels 'sprites/square/blue.png'
    args.pixel_array(:square).w = pixel_array.w
    args.pixel_array(:square).h = pixel_array.h
    pixel_array.pixels.each_with_index do |p, i|
      args.pixel_array(:square).pixels[i] = p
    end
  end

  w = 100
  h = 100
  x = (1280 - w) / 2
  y = (720 - h) / 2
  args.outputs.background_color = [64, 0, 128]
  # render the pixel array by name
  args.outputs.primitives << { x: x, y: y, w: w, h: h, path: :square, angle: args.state.rotation }
  args.state.rotation += 1

  args.outputs.primitives << args.gtk.current_framerate_primitives
end

$gtk.reset

    Shake Camera - main.rb link

    # ./samples/07_advanced_rendering/07_shake_camera/app/main.rb
# Demo of camera shake
# Hold space to shake and release to stop

class ScreenShake
  attr_gtk

  def tick
    defaults
    calc_camera

    outputs.labels << { x: 600, y: 400, text: "Hold Space!" }

    # Add outputs to :scene
    outputs[:scene].transient!
    outputs[:scene].sprites << { x: 100, y: 100,          w: 80, h: 80, path: 'sprites/square/blue.png' }
    outputs[:scene].sprites << { x: 200, y: 300.from_top, w: 80, h: 80, path: 'sprites/square/blue.png' }
    outputs[:scene].sprites << { x: 900, y: 200,          w: 80, h: 80, path: 'sprites/square/blue.png' }

    # Describe how to render :scene
    outputs.sprites << { x: 0 - state.camera.x_offset,
                         y: 0 - state.camera.y_offset,
                         w: 1280,
                         h: 720,
                         angle: state.camera.angle,
                         path: :scene }
  end

  def defaults
    state.camera.trauma ||= 0
    state.camera.angle ||= 0
    state.camera.x_offset ||= 0
    state.camera.y_offset ||= 0
  end

  def calc_camera
    if inputs.keyboard.key_held.space
      state.camera.trauma += 0.02
    end

    next_camera_angle = 180.0 / 20.0 * state.camera.trauma**2
    next_offset       = 100.0 * state.camera.trauma**2

    # Ensure that the camera angle always switches from
    # positive to negative and vice versa
    # which gives the effect of shaking back and forth
    state.camera.angle = state.camera.angle > 0 ?
                           next_camera_angle * -1 :
                           next_camera_angle

    state.camera.x_offset = next_offset.randomize(:sign, :ratio)
    state.camera.y_offset = next_offset.randomize(:sign, :ratio)

    # Gracefully degrade trauma
    state.camera.trauma *= 0.95
  end
end

def tick args
  $screen_shake ||= ScreenShake.new
  $screen_shake.args = args
  $screen_shake.tick
end

    Simple Camera - main.rb link

    # ./samples/07_advanced_rendering/07_simple_camera/app/main.rb
def tick args
  # variables you can play around with
  args.state.world.w      ||= 1280
  args.state.world.h      ||= 720

  args.state.player.x     ||= 0
  args.state.player.y     ||= 0
  args.state.player.size  ||= 32

  args.state.enemy.x      ||= 700
  args.state.enemy.y      ||= 700
  args.state.enemy.size   ||= 16

  args.state.camera.x                ||= 640
  args.state.camera.y                ||= 300
  args.state.camera.scale            ||= 1.0
  args.state.camera.show_empty_space ||= :yes

  # instructions
  args.outputs.primitives << { x: 0, y:  80.from_top, w: 360, h: 80, r: 0, g: 0, b: 0, a: 128 }.solid!
  args.outputs.primitives << { x: 10, y: 10.from_top, text: "arrow keys to move around", r: 255, g: 255, b: 255}.label!
  args.outputs.primitives << { x: 10, y: 30.from_top, text: "+/- to change zoom of camera", r: 255, g: 255, b: 255}.label!
  args.outputs.primitives << { x: 10, y: 50.from_top, text: "tab to change camera edge behavior", r: 255, g: 255, b: 255}.label!

  # render scene
  args.outputs[:scene].transient!
  args.outputs[:scene].w = args.state.world.w
  args.outputs[:scene].h = args.state.world.h

  args.outputs[:scene].solids << { x: 0, y: 0, w: args.state.world.w, h: args.state.world.h, r: 20, g: 60, b: 80 }
  args.outputs[:scene].solids << { x: args.state.player.x, y: args.state.player.y,
                                   w: args.state.player.size, h: args.state.player.size, r: 80, g: 155, b: 80 }
  args.outputs[:scene].solids << { x: args.state.enemy.x, y: args.state.enemy.y,
                                   w: args.state.enemy.size, h: args.state.enemy.size, r: 155, g: 80, b: 80 }

  # render camera
  scene_position = calc_scene_position args
  args.outputs.sprites << { x: scene_position.x,
                            y: scene_position.y,
                            w: scene_position.w,
                            h: scene_position.h,
                            path: :scene }

  # move player
  if args.inputs.directional_angle
    args.state.player.x += args.inputs.directional_angle.vector_x * 5
    args.state.player.y += args.inputs.directional_angle.vector_y * 5
    args.state.player.x  = args.state.player.x.clamp(0, args.state.world.w - args.state.player.size)
    args.state.player.y  = args.state.player.y.clamp(0, args.state.world.h - args.state.player.size)
  end

  # +/- to zoom in and out
  if args.inputs.keyboard.plus && args.state.tick_count.zmod?(3)
    args.state.camera.scale += 0.05
  elsif args.inputs.keyboard.hyphen && args.state.tick_count.zmod?(3)
    args.state.camera.scale -= 0.05
  elsif args.inputs.keyboard.key_down.tab
    if args.state.camera.show_empty_space == :yes
      args.state.camera.show_empty_space = :no
    else
      args.state.camera.show_empty_space = :yes
    end
  end

  args.state.camera.scale = args.state.camera.scale.greater(0.1)
end

def calc_scene_position args
  result = { x: args.state.camera.x - (args.state.player.x * args.state.camera.scale),
             y: args.state.camera.y - (args.state.player.y * args.state.camera.scale),
             w: args.state.world.w * args.state.camera.scale,
             h: args.state.world.h * args.state.camera.scale,
             scale: args.state.camera.scale }

  return result if args.state.camera.show_empty_space == :yes

  if result.w < args.grid.w
    result.merge!(x: (args.grid.w - result.w).half)
  elsif (args.state.player.x * result.scale) < args.grid.w.half
    result.merge!(x: 10)
  elsif (result.x + result.w) < args.grid.w
    result.merge!(x: - result.w + (args.grid.w - 10))
  end

  if result.h < args.grid.h
    result.merge!(y: (args.grid.h - result.h).half)
  elsif (result.y) > 10
    result.merge!(y: 10)
  elsif (result.y + result.h) < args.grid.h
    result.merge!(y: - result.h + (args.grid.h - 10))
  end

  result
end

    Simple Camera Multiple Targets - main.rb link

    # ./samples/07_advanced_rendering/07_simple_camera_multiple_targets/app/main.rb
def tick args
  args.outputs.background_color = [0, 0, 0]

  # variables you can play around with
  args.state.world.w                ||= 1280
  args.state.world.h                ||= 720
  args.state.target_hero            ||= :hero_1
  args.state.target_hero_changed_at ||= -30
  args.state.hero_size              ||= 32

  # initial state of heros and camera
  args.state.hero_1 ||= { x: 100, y: 100 }
  args.state.hero_2 ||= { x: 100, y: 600 }
  args.state.camera ||= { x: 640, y: 360, scale: 1.0 }

  # render instructions
  args.outputs.primitives << { x: 0,  y: 80.from_top, w: 360, h: 80, r: 0, g: 0, b: 0, a: 128 }.solid!
  args.outputs.primitives << { x: 10, y: 10.from_top, text: "+/- to change zoom of camera", r: 255, g: 255, b: 255}.label!
  args.outputs.primitives << { x: 10, y: 30.from_top, text: "arrow keys to move target hero", r: 255, g: 255, b: 255}.label!
  args.outputs.primitives << { x: 10, y: 50.from_top, text: "space to cycle target hero", r: 255, g: 255, b: 255}.label!

  # render scene
  args.outputs[:scene].transient!
  args.outputs[:scene].w = args.state.world.w
  args.outputs[:scene].h = args.state.world.h

  # render world
  args.outputs[:scene].solids << { x: 0, y: 0, w: args.state.world.w, h: args.state.world.h, r: 20, g: 60, b: 80 }

  # render hero_1
  args.outputs[:scene].solids << { x: args.state.hero_1.x, y: args.state.hero_1.y,
                                   w: args.state.hero_size, h: args.state.hero_size, r: 255, g: 155, b: 80 }

  # render hero_2
  args.outputs[:scene].solids << { x: args.state.hero_2.x, y: args.state.hero_2.y,
                                   w: args.state.hero_size, h: args.state.hero_size, r: 155, g: 255, b: 155 }

  # render scene relative to camera
  scene_position = calc_scene_position args

  args.outputs.sprites << { x: scene_position.x,
                            y: scene_position.y,
                            w: scene_position.w,
                            h: scene_position.h,
                            path: :scene }

  # mini map
  args.outputs.borders << { x: 10,
                            y: 10,
                            w: args.state.world.w.idiv(8),
                            h: args.state.world.h.idiv(8),
                            r: 255,
                            g: 255,
                            b: 255 }
  args.outputs.sprites << { x: 10,
                            y: 10,
                            w: args.state.world.w.idiv(8),
                            h: args.state.world.h.idiv(8),
                            path: :scene }

  # cycle target hero
  if args.inputs.keyboard.key_down.space
    if args.state.target_hero == :hero_1
      args.state.target_hero = :hero_2
    else
      args.state.target_hero = :hero_1
    end
    args.state.target_hero_changed_at = args.state.tick_count
  end

  # move target hero
  hero_to_move = if args.state.target_hero == :hero_1
                   args.state.hero_1
                 else
                   args.state.hero_2
                 end

  if args.inputs.directional_angle
    hero_to_move.x += args.inputs.directional_angle.vector_x * 5
    hero_to_move.y += args.inputs.directional_angle.vector_y * 5
    hero_to_move.x  = hero_to_move.x.clamp(0, args.state.world.w - hero_to_move.size)
    hero_to_move.y  = hero_to_move.y.clamp(0, args.state.world.h - hero_to_move.size)
  end

  # +/- to zoom in and out
  if args.inputs.keyboard.plus && args.state.tick_count.zmod?(3)
    args.state.camera.scale += 0.05
  elsif args.inputs.keyboard.hyphen && args.state.tick_count.zmod?(3)
    args.state.camera.scale -= 0.05
  end

  args.state.camera.scale = 0.1 if args.state.camera.scale < 0.1
end

def other_hero args
  if args.state.target_hero == :hero_1
    return args.state.hero_2
  else
    return args.state.hero_1
  end
end

def calc_scene_position args
  target_hero = if args.state.target_hero == :hero_1
                  args.state.hero_1
                else
                  args.state.hero_2
                end

  other_hero = if args.state.target_hero == :hero_1
                 args.state.hero_2
               else
                 args.state.hero_1
               end

  # calculate the lerp percentage based on the time since the target hero changed
  lerp_percentage = args.easing.ease args.state.target_hero_changed_at,
                                     args.state.tick_count,
                                     30,
                                     :smooth_stop_quint,
                                     :flip

  # calculate the angle and distance between the target hero and the other hero
  angle_to_other_hero = args.geometry.angle_to target_hero, other_hero

  # calculate the distance between the target hero and the other hero
  distance_to_other_hero = args.geometry.distance target_hero, other_hero

  # the camera position is the target hero position plus the angle and distance to the other hero (lerped)
  { x: args.state.camera.x - (target_hero.x + (angle_to_other_hero.vector_x * distance_to_other_hero * lerp_percentage)) * args.state.camera.scale,
    y: args.state.camera.y - (target_hero.y + (angle_to_other_hero.vector_y * distance_to_other_hero * lerp_percentage)) * args.state.camera.scale,
    w: args.state.world.w * args.state.camera.scale,
    h: args.state.world.h * args.state.camera.scale }
end

    Splitscreen Camera - main.rb link

    # ./samples/07_advanced_rendering/08_splitscreen_camera/app/main.rb
class CameraMovement
  attr_accessor :state, :inputs, :outputs, :grid

  #==============================================================================================
  #Serialize
  def serialize
    {state: state, inputs: inputs, outputs: outputs, grid: grid }
  end

  def inspect
    serialize.to_s
  end

  def to_s
    serialize.to_s
  end

  #==============================================================================================
  #Tick
  def tick
    defaults
    calc
    render
    input
  end

  #==============================================================================================
  #Default functions
  def defaults
    outputs[:scene].transient!
    outputs[:scene].background_color = [0,0,0]
    state.trauma ||= 0.0
    state.trauma_power ||= 2
    state.player_cyan ||= new_player_cyan
    state.player_magenta ||= new_player_magenta
    state.camera_magenta ||= new_camera_magenta
    state.camera_cyan ||= new_camera_cyan
    state.camera_center ||= new_camera_center
    state.room ||= new_room
  end

  def default_player x, y, w, h, sprite_path
    state.new_entity(:player,
                     { x: x,
                       y: y,
                       dy: 0,
                       dx: 0,
                       w: w,
                       h: h,
                       damage: 0,
                       dead: false,
                       orientation: "down",
                       max_alpha: 255,
                       sprite_path: sprite_path})
  end

  def default_floor_tile x, y, w, h, sprite_path
    state.new_entity(:room,
                     { x: x,
                       y: y,
                       w: w,
                       h: h,
                       sprite_path: sprite_path})
  end

  def default_camera x, y, w, h
    state.new_entity(:camera,
                     { x: x,
                       y: y,
                       dx: 0,
                       dy: 0,
                       w: w,
                       h: h})
  end

  def new_player_cyan
    default_player(0, 0, 64, 64,
                   "sprites/player/player_#{state.player_cyan.orientation}_standing.png")
  end

  def new_player_magenta
    default_player(64, 0, 64, 64,
                   "sprites/player/player_#{state.player_magenta.orientation}_standing.png")
  end

  def new_camera_magenta
    default_camera(0,0,720,720)
  end

  def new_camera_cyan
    default_camera(0,0,720,720)
  end

  def new_camera_center
    default_camera(0,0,1280,720)
  end


  def new_room
    default_floor_tile(0,0,1024,1024,'sprites/rooms/camera_room.png')
  end

  #==============================================================================================
  #Calculation functions
  def calc
    calc_camera_magenta
    calc_camera_cyan
    calc_camera_center
    calc_player_cyan
    calc_player_magenta
    calc_trauma_decay
  end

  def center_camera_tolerance
    return Math.sqrt(((state.player_magenta.x - state.player_cyan.x) ** 2) +
              ((state.player_magenta.y - state.player_cyan.y) ** 2)) > 640
  end

  def calc_player_cyan
    state.player_cyan.x += state.player_cyan.dx
    state.player_cyan.y += state.player_cyan.dy
  end

  def calc_player_magenta
    state.player_magenta.x += state.player_magenta.dx
    state.player_magenta.y += state.player_magenta.dy
  end

  def calc_camera_center
    timeScale = 1
    midX = (state.player_magenta.x + state.player_cyan.x)/2
    midY = (state.player_magenta.y + state.player_cyan.y)/2
    targetX = midX - state.camera_center.w/2
    targetY = midY - state.camera_center.h/2
    state.camera_center.x += (targetX - state.camera_center.x) * 0.1 * timeScale
    state.camera_center.y += (targetY - state.camera_center.y) * 0.1 * timeScale
  end


  def calc_camera_magenta
    timeScale = 1
    targetX = state.player_magenta.x + state.player_magenta.w - state.camera_magenta.w/2
    targetY = state.player_magenta.y + state.player_magenta.h - state.camera_magenta.h/2
    state.camera_magenta.x += (targetX - state.camera_magenta.x) * 0.1 * timeScale
    state.camera_magenta.y += (targetY - state.camera_magenta.y) * 0.1 * timeScale
  end

  def calc_camera_cyan
    timeScale = 1
    targetX = state.player_cyan.x + state.player_cyan.w - state.camera_cyan.w/2
    targetY = state.player_cyan.y + state.player_cyan.h - state.camera_cyan.h/2
    state.camera_cyan.x += (targetX - state.camera_cyan.x) * 0.1 * timeScale
    state.camera_cyan.y += (targetY - state.camera_cyan.y) * 0.1 * timeScale
  end

  def calc_player_quadrant angle
    if angle < 45 and angle > -45 and state.player_cyan.x < state.player_magenta.x
      return 1
    elsif angle < 45 and angle > -45 and state.player_cyan.x > state.player_magenta.x
      return 3
    elsif (angle > 45 or angle < -45) and state.player_cyan.y < state.player_magenta.y
      return 2
    elsif (angle > 45 or angle < -45) and state.player_cyan.y > state.player_magenta.y
      return 4
    end
  end

  def calc_camera_shake
    state.trauma
  end

  def calc_trauma_decay
    state.trauma = state.trauma * 0.9
  end

  def calc_random_float_range(min, max)
    rand * (max-min) + min
  end

  #==============================================================================================
  #Render Functions
  def render
    render_floor
    render_player_cyan
    render_player_magenta
    if center_camera_tolerance
      render_split_camera_scene
    else
      render_camera_center_scene
    end
  end

  def render_player_cyan
    outputs[:scene].sprites << {x: state.player_cyan.x,
                                y: state.player_cyan.y,
                                w: state.player_cyan.w,
                                h: state.player_cyan.h,
                                path: "sprites/player/player_#{state.player_cyan.orientation}_standing.png",
                                r: 0,
                                g: 255,
                                b: 255}
  end

  def render_player_magenta
    outputs[:scene].sprites << {x: state.player_magenta.x,
                                y: state.player_magenta.y,
                                w: state.player_magenta.w,
                                h: state.player_magenta.h,
                                path: "sprites/player/player_#{state.player_magenta.orientation}_standing.png",
                                r: 255,
                                g: 0,
                                b: 255}
  end

  def render_floor
    outputs[:scene].sprites << [state.room.x, state.room.y,
                                state.room.w, state.room.h,
                                state.room.sprite_path]
  end

  def render_camera_center_scene
    zoomFactor = 1
    outputs[:scene].width = state.room.w
    outputs[:scene].height = state.room.h

    maxAngle = 10.0
    maxOffset = 20.0
    angle = maxAngle * calc_camera_shake * calc_random_float_range(-1,1)
    offsetX = 32 - (maxOffset * calc_camera_shake * calc_random_float_range(-1,1))
    offsetY = 32 - (maxOffset * calc_camera_shake * calc_random_float_range(-1,1))

    outputs.sprites << {x: (-state.camera_center.x - offsetX)/zoomFactor,
                        y: (-state.camera_center.y - offsetY)/zoomFactor,
                        w: outputs[:scene].width/zoomFactor,
                        h: outputs[:scene].height/zoomFactor,
                        path: :scene,
                        angle: angle,
                        source_w: -1,
                        source_h: -1}
    outputs.labels << [128,64,"#{state.trauma.round(1)}",8,2,255,0,255,255]
  end

  def render_split_camera_scene
     outputs[:scene].width = state.room.w
     outputs[:scene].height = state.room.h
     render_camera_magenta_scene
     render_camera_cyan_scene

     angle = Math.atan((state.player_magenta.y - state.player_cyan.y)/(state.player_magenta.x- state.player_cyan.x)) * 180/Math::PI
     output_split_camera angle

  end

  def render_camera_magenta_scene
     zoomFactor = 1
     offsetX = 32
     offsetY = 32

     outputs[:scene_magenta].transient!
     outputs[:scene_magenta].sprites << {x: (-state.camera_magenta.x*2),
                                         y: (-state.camera_magenta.y),
                                         w: outputs[:scene].width*2,
                                         h: outputs[:scene].height,
                                         path: :scene}

  end

  def render_camera_cyan_scene
    zoomFactor = 1
    offsetX = 32
    offsetY = 32
    outputs[:scene_cyan].transient!
    outputs[:scene_cyan].sprites << {x: (-state.camera_cyan.x*2),
                                     y: (-state.camera_cyan.y),
                                     w: outputs[:scene].width*2,
                                     h: outputs[:scene].height,
                                     path: :scene}
  end

  def output_split_camera angle
    #TODO: Clean this up!
    quadrant = calc_player_quadrant angle
    outputs.labels << [128,64,"#{quadrant}",8,2,255,0,255,255]
    if quadrant == 1
      set_camera_attributes(w: 640, h: 720, m_x: 640, m_y: 0, c_x: 0, c_y: 0)

    elsif quadrant == 2
      set_camera_attributes(w: 1280, h: 360, m_x: 0, m_y: 360, c_x: 0, c_y: 0)

    elsif quadrant == 3
      set_camera_attributes(w: 640, h: 720, m_x: 0, m_y: 0, c_x: 640, c_y: 0)

    elsif quadrant == 4
      set_camera_attributes(w: 1280, h: 360, m_x: 0, m_y: 0, c_x: 0, c_y: 360)

    end
  end

  def set_camera_attributes(w: 0, h: 0, m_x: 0, m_y: 0, c_x: 0, c_y: 0)
    state.camera_cyan.w = w + 64
    state.camera_cyan.h = h + 64
    outputs[:scene_cyan].width = (w) * 2
    outputs[:scene_cyan].height = h

    state.camera_magenta.w = w + 64
    state.camera_magenta.h = h + 64
    outputs[:scene_magenta].width = (w) * 2
    outputs[:scene_magenta].height = h
    outputs.sprites << {x: m_x,
                        y: m_y,
                        w: w,
                        h: h,
                        path: :scene_magenta}
    outputs.sprites << {x: c_x,
                        y: c_y,
                        w: w,
                        h: h,
                        path: :scene_cyan}
  end

  def add_trauma amount
    state.trauma = [state.trauma + amount, 1.0].min
  end

  def remove_trauma amount
    state.trauma = [state.trauma - amount, 0.0].max
  end
  #==============================================================================================
  #Input functions
  def input
    input_move_cyan
    input_move_magenta

    if inputs.keyboard.key_down.t
      add_trauma(0.5)
    elsif inputs.keyboard.key_down.y
      remove_trauma(0.1)
    end
  end

  def input_move_cyan
    if inputs.keyboard.key_held.up
      state.player_cyan.dy = 5
      state.player_cyan.orientation = "up"
    elsif inputs.keyboard.key_held.down
      state.player_cyan.dy = -5
      state.player_cyan.orientation = "down"
    else
      state.player_cyan.dy *= 0.8
    end
    if inputs.keyboard.key_held.left
      state.player_cyan.dx = -5
      state.player_cyan.orientation = "left"
    elsif inputs.keyboard.key_held.right
      state.player_cyan.dx = 5
      state.player_cyan.orientation = "right"
    else
      state.player_cyan.dx *= 0.8
    end

    outputs.labels << [128,512,"#{state.player_cyan.x.round()}",8,2,0,255,255,255]
    outputs.labels << [128,480,"#{state.player_cyan.y.round()}",8,2,0,255,255,255]
  end

  def input_move_magenta
    if inputs.keyboard.key_held.w
      state.player_magenta.dy = 5
      state.player_magenta.orientation = "up"
    elsif inputs.keyboard.key_held.s
      state.player_magenta.dy = -5
      state.player_magenta.orientation = "down"
    else
      state.player_magenta.dy *= 0.8
    end
    if inputs.keyboard.key_held.a
      state.player_magenta.dx = -5
      state.player_magenta.orientation = "left"
    elsif inputs.keyboard.key_held.d
      state.player_magenta.dx = 5
      state.player_magenta.orientation = "right"
    else
      state.player_magenta.dx *= 0.8
    end

    outputs.labels << [128,360,"#{state.player_magenta.x.round()}",8,2,255,0,255,255]
    outputs.labels << [128,328,"#{state.player_magenta.y.round()}",8,2,255,0,255,255]
  end
end

$camera_movement = CameraMovement.new

def tick args
  args.outputs.background_color = [0,0,0]
  $camera_movement.inputs  = args.inputs
  $camera_movement.outputs = args.outputs
  $camera_movement.state   = args.state
  $camera_movement.grid    = args.grid
  $camera_movement.tick
end

    Z Targeting Camera - main.rb link

    # ./samples/07_advanced_rendering/09_z_targeting_camera/app/main.rb
class Game
  attr_gtk

  def tick
    defaults
    render
    input
    calc
  end

  def defaults
    outputs.background_color = [219, 208, 191]
    player.x        ||= 634
    player.y        ||= 153
    player.angle    ||= 90
    player.distance ||= arena_radius
    target.x        ||= 634
    target.y        ||= 359
  end

  def render
    outputs[:scene].transient!
    outputs[:scene].sprites << ({ x: 0, y: 0, w: 933, h: 700, path: 'sprites/arena.png' }.center_inside_rect grid.rect)
    outputs[:scene].sprites << target_sprite
    outputs[:scene].sprites << player_sprite
    outputs.sprites << scene
  end

  def target_sprite
    {
      x: target.x, y: target.y,
      w: 10, h: 10,
      path: 'sprites/square/black.png'
    }.anchor_rect 0.5, 0.5
  end

  def input
    if inputs.up && player.distance > 30
      player.distance -= 2
    elsif inputs.down && player.distance < 200
      player.distance += 2
    end

    player.angle += inputs.left_right * -1
  end

  def calc
    player.x = target.x + ((player.angle *  1).vector_x player.distance)
    player.y = target.y + ((player.angle * -1).vector_y player.distance)
  end

  def player_sprite
    {
      x: player.x,
      y: player.y,
      w: 50,
      h: 100,
      path: 'sprites/player.png',
      angle: (player.angle * -1) + 90
    }.anchor_rect 0.5, 0
  end

  def center_map
    { x: 634, y: 359 }
  end

  def zoom_factor_single
    2 - ((args.geometry.distance player, center_map).fdiv arena_radius)
  end

  def zoom_factor
    zoom_factor_single ** 2
  end

  def arena_radius
    206
  end

  def scene
    {
      x:    (640 - player.x) + (640 - (640 * zoom_factor)),
      y:    (360 - player.y - (75 * zoom_factor)) + (320 - (320 * zoom_factor)),
      w:    1280 * zoom_factor,
      h:     720 * zoom_factor,
      path: :scene,
      angle: player.angle - 90,
      angle_anchor_x: (player.x.fdiv 1280),
      angle_anchor_y: (player.y.fdiv 720)
    }
  end

  def player
    state.player
  end

  def target
    state.target
  end
end

def tick args
  $game ||= Game.new
  $game.args = args
  $game.tick
end

$gtk.reset

    Camera And Large Map - main.rb link

    # ./samples/07_advanced_rendering/10_camera_and_large_map/app/main.rb
def tick args
  # you want to make sure all of your pngs are a maximum size of 1280x1280
  # low-end android devices and machines with underpowered GPUs are unable to
  # load very large textures.

  # this sample app creates 640x640 tiles of a 6400x6400 pixel png and displays them
  # on the screen relative to the player's position

  # tile creation process
  create_tiles_if_needed args

  # if tiles are already present the show map
  display_tiles args
end

def display_tiles args
  # set the player's starting location
  args.state.player ||= {
    x:  0,
    y:  0,
    w: 40,
    h: 40,
    path: "sprites/square/blue.png"
  }

  # if all tiles have been created, then we are
  # in "displaying_tiles" mode
  if args.state.displaying_tiles
    # create a render target that can hold 9 640x640 tiles
    args.outputs[:scene].transient!
    args.outputs[:scene].background_color = [0, 0, 0, 0]
    args.outputs[:scene].w = 1920
    args.outputs[:scene].h = 1920

    # allow player to be moved with arrow keys
    args.state.player.x += args.inputs.left_right * 10
    args.state.player.y += args.inputs.up_down * 10

    # given the player's location, return a collection of primitives
    # to render that are within the 1920x1920 viewport
    args.outputs[:scene].primitives << tiles_in_viewport(args)

    # place the player in the center of the render_target
    args.outputs[:scene].primitives << {
      x: 960 - 20,
      y: 960 - 20,
      w: 40,
      h: 40,
      path: "sprites/square/blue.png"
    }

    # center the 1920x1920 render target within the 1280x720 window
    args.outputs.sprites << {
      x: -320,
      y: -600,
      w: 1920,
      h: 1920,
      path: :scene
    }
  end
end

def tiles_in_viewport args
  state = args.state
  # define the size of each tile
  tile_size = 640

  # determine what tile the player is on
  tile_player_is_on = { x: state.player.x.idiv(tile_size), y: state.player.y.idiv(tile_size) }

  # calculate the x and y offset of the player so that tiles are positioned correctly
  offset_x = 960 - (state.player.x - (tile_player_is_on.x * tile_size))
  offset_y = 960 - (state.player.y - (tile_player_is_on.y * tile_size))

  primitives = []

  # get 9 tiles in total (the tile the player is on and the 8 surrounding tiles)

  # center tile
  primitives << (tile_in_viewport size:       tile_size,
                                  from_row:   tile_player_is_on.y,
                                  from_col:   tile_player_is_on.x,
                                  offset_row: 0,
                                  offset_col: 0,
                                  dy:         offset_y,
                                  dx:         offset_x)

  # tile to the right
  primitives << (tile_in_viewport size:       tile_size,
                                  from_row:   tile_player_is_on.y,
                                  from_col:   tile_player_is_on.x,
                                  offset_row: 0,
                                  offset_col: 1,
                                  dy:         offset_y,
                                  dx:         offset_x)
  # tile to the left
  primitives << (tile_in_viewport size:        tile_size,
                                  from_row:    tile_player_is_on.y,
                                  from_col:    tile_player_is_on.x,
                                  offset_row:  0,
                                  offset_col: -1,
                                  dy:          offset_y,
                                  dx:          offset_x)

  # tile directly above
  primitives << (tile_in_viewport size:       tile_size,
                                  from_row:   tile_player_is_on.y,
                                  from_col:   tile_player_is_on.x,
                                  offset_row: 1,
                                  offset_col: 0,
                                  dy:         offset_y,
                                  dx:         offset_x)
  # tile directly below
  primitives << (tile_in_viewport size:         tile_size,
                                  from_row:     tile_player_is_on.y,
                                  from_col:     tile_player_is_on.x,
                                  offset_row:  -1,
                                  offset_col:   0,
                                  dy:           offset_y,
                                  dx:           offset_x)
  # tile up and to the left
  primitives << (tile_in_viewport size:        tile_size,
                                  from_row:    tile_player_is_on.y,
                                  from_col:    tile_player_is_on.x,
                                  offset_row:  1,
                                  offset_col: -1,
                                  dy:          offset_y,
                                  dx:          offset_x)

  # tile up and to the right
  primitives << (tile_in_viewport size:       tile_size,
                                  from_row:   tile_player_is_on.y,
                                  from_col:   tile_player_is_on.x,
                                  offset_row: 1,
                                  offset_col: 1,
                                  dy:         offset_y,
                                  dx:         offset_x)

  # tile down and to the left
  primitives << (tile_in_viewport size:        tile_size,
                                  from_row:    tile_player_is_on.y,
                                  from_col:    tile_player_is_on.x,
                                  offset_row: -1,
                                  offset_col: -1,
                                  dy:          offset_y,
                                  dx:          offset_x)

  # tile down and to the right
  primitives << (tile_in_viewport size:        tile_size,
                                  from_row:    tile_player_is_on.y,
                                  from_col:    tile_player_is_on.x,
                                  offset_row: -1,
                                  offset_col:  1,
                                  dy:          offset_y,
                                  dx:          offset_x)

  primitives
end

def tile_in_viewport size:, from_row:, from_col:, offset_row:, offset_col:, dy:, dx:;
  x = size * offset_col + dx
  y = size * offset_row + dy

  return nil if (from_row + offset_row) < 0
  return nil if (from_row + offset_row) > 9

  return nil if (from_col + offset_col) < 0
  return nil if (from_col + offset_col) > 9

  # return the tile sprite, a border demarcation, and label of which tile x and y
  [
    {
      x: x,
      y: y,
      w: size,
      h: size,
      path: "sprites/tile-#{from_col + offset_col}-#{from_row + offset_row}.png",
    },
    {
      x: x,
      y: y,
      w: size,
      h: size,
      r: 255,
      primitive_marker: :border,
    },
    {
      x: x + size / 2 - 150,
      y: y + size / 2 - 25,
      w: 300,
      h: 50,
      primitive_marker: :solid,
      r: 0,
      g: 0,
      b: 0,
      a: 128
    },
    {
      x: x + size / 2,
      y: y + size / 2,
      text: "tile #{from_col + offset_col}, #{from_row + offset_row}",
      alignment_enum: 1,
      vertical_alignment_enum: 1,
      size_enum: 2,
      r: 255,
      g: 255,
      b: 255
    },
  ]
end

def create_tiles_if_needed args
  # We are going to use args.outputs.screenshots to generate tiles of a
  # png of size 6400x6400 called sprites/large.png.
  if !args.gtk.stat_file("sprites/tile-9-9.png") && !args.state.creating_tiles
    args.state.displaying_tiles = false
    args.outputs.labels << {
      x: 960,
      y: 360,
      text: "Press enter to generate tiles of sprites/large.png.",
      alignment_enum: 1,
      vertical_alignment_enum: 1
    }
  elsif !args.state.creating_tiles
    args.state.displaying_tiles = true
  end

  # pressing enter will start the tile creation process
  if args.inputs.keyboard.key_down.enter && !args.state.creating_tiles
    args.state.displaying_tiles = false
    args.state.creating_tiles = true
    args.state.tile_clock = 0
  end

  # the tile creation process renders an area of sprites/large.png
  # to the screen and takes a screenshot of it every half second
  # until all tiles are generated.
  # once all tiles are generated a map viewport will be rendered that
  # stitches tiles together.
  if args.state.creating_tiles
    args.state.tile_x ||= 0
    args.state.tile_y ||= 0

    # render a sub-square of the large png.
    args.outputs.sprites << {
      x: 0,
      y: 0,
      w: 640,
      h: 640,
      source_x: args.state.tile_x * 640,
      source_y: args.state.tile_y * 640,
      source_w: 640,
      source_h: 640,
      path: "sprites/large.png"
    }

    # determine tile file name
    tile_path = "sprites/tile-#{args.state.tile_x}-#{args.state.tile_y}.png"

    args.outputs.labels << {
      x: 960,
      y: 320,
      text: "Generating #{tile_path}",
      alignment_enum: 1,
      vertical_alignment_enum: 1
    }

    # take a screenshot on frames divisible by 29
    if args.state.tile_clock.zmod?(29)
      args.outputs.screenshots << {
        x: 0,
        y: 0,
        w: 640,
        h: 640,
        path: tile_path,
        a: 255
      }
    end

    # increment tile to render on frames divisible by 30 (half a second)
    # (one frame is allotted to take screenshot)
    if args.state.tile_clock.zmod?(30)
      args.state.tile_x += 1
      if args.state.tile_x >= 10
        args.state.tile_x  = 0
        args.state.tile_y += 1
      end

      # once all of tile tiles are created, begin displaying map
      if args.state.tile_y >= 10
        args.state.creating_tiles = false
        args.state.displaying_tiles = true
      end
    end

    args.state.tile_clock += 1
  end
end

$gtk.reset

    Blend Modes - main.rb link

    # ./samples/07_advanced_rendering/11_blend_modes/app/main.rb
$gtk.reset

def draw_blendmode args, mode
  w = 160
  h = w
  args.state.x += (1280-w) / (args.state.blendmodes.length + 1)
  x = args.state.x
  y = (720 - h) / 2
  s = 'sprites/blue-feathered.png'
  args.outputs.sprites << { blendmode_enum: mode.value, x: x, y: y, w: w, h: h, path: s }
  args.outputs.labels << [x + (w/2), y, mode.name.to_s, 1, 1, 255, 255, 255]
end

def tick args

  # Different blend modes do different things, depending on what they
  # blend against (in this case, the pixels of the background color).
  args.state.bg_element ||= 1
  args.state.bg_color ||= 255
  args.state.bg_color_direction ||= 1
  bg_r = (args.state.bg_element == 1) ? args.state.bg_color : 0
  bg_g = (args.state.bg_element == 2) ? args.state.bg_color : 0
  bg_b = (args.state.bg_element == 3) ? args.state.bg_color : 0
  args.state.bg_color += args.state.bg_color_direction
  if (args.state.bg_color_direction > 0) && (args.state.bg_color >= 255)
    args.state.bg_color_direction = -1
    args.state.bg_color = 255
  elsif (args.state.bg_color_direction < 0) && (args.state.bg_color <= 0)
    args.state.bg_color_direction = 1
    args.state.bg_color = 0
    args.state.bg_element += 1
    if args.state.bg_element >= 4
      args.state.bg_element = 1
    end
  end

  args.outputs.background_color = [ bg_r, bg_g, bg_b, 255 ]

  args.state.blendmodes ||= [
    { name: :none,  value: 0 },
    { name: :blend, value: 1 },
    { name: :add,   value: 2 },
    { name: :mod,   value: 3 },
    { name: :mul,   value: 4 }
  ]

  args.state.x = 0  # reset this, draw_blendmode will increment it.
  args.state.blendmodes.each { |blendmode| draw_blendmode args, blendmode }
end

    Render Target Noclear - main.rb link

    # ./samples/07_advanced_rendering/12_render_target_noclear/app/main.rb
def tick args
  args.state.x ||= 500
  args.state.y ||= 350
  args.state.xinc ||= 7
  args.state.yinc ||= 7
  args.state.bgcolor ||= 1
  args.state.bginc ||= 1

  # clear the render target on the first tick, and then never again. Draw
  #  another box to it every tick, accumulating over time.
  clear_target = (args.state.tick_count == 0) || (args.inputs.keyboard.key_down.space)
  args.render_target(:accumulation).transient = true
  args.render_target(:accumulation).background_color = [ 0, 0, 0, 0 ];
  args.render_target(:accumulation).clear_before_render = clear_target
  args.render_target(:accumulation).solids << [args.state.x, args.state.y, 25, 25, 255, 0, 0, 255];
  args.state.x += args.state.xinc
  args.state.y += args.state.yinc
  args.state.bgcolor += args.state.bginc

  # animation upkeep...change where we draw the next box and what color the
  #  window background will be.
  if args.state.xinc > 0 && args.state.x >= 1280
    args.state.xinc = -7
  elsif args.state.xinc < 0 && args.state.x < 0
    args.state.xinc = 7
  end

  if args.state.yinc > 0 && args.state.y >= 720
    args.state.yinc = -7
  elsif args.state.yinc < 0 && args.state.y < 0
    args.state.yinc = 7
  end

  if args.state.bginc > 0 && args.state.bgcolor >= 255
    args.state.bginc = -1
  elsif args.state.bginc < 0 && args.state.bgcolor <= 0
    args.state.bginc = 1
  end

  # clear the screen to a shade of blue and draw the render target, which
  #  is not clearing every frame, on top of it. Note that you can NOT opt to
  #  skip clearing the screen, only render targets. The screen clears every
  #  frame; double-buffering would prevent correct updates between frames.
  args.outputs.background_color = [ 0, 0, args.state.bgcolor, 255 ]
  args.outputs.sprites << [ 0, 0, 1280, 720, :accumulation ]
end

$gtk.reset

    Lighting - main.rb link

    # ./samples/07_advanced_rendering/13_lighting/app/main.rb
def calc args
  args.state.swinging_light_sign     ||= 1
  args.state.swinging_light_start_at ||= 0
  args.state.swinging_light_duration ||= 300
  args.state.swinging_light_perc       = args.state
                                             .swinging_light_start_at
                                             .ease_spline_extended args.state.tick_count,
                                                                   args.state.swinging_light_duration,
                                                                   [
                                                                     [0.0, 1.0, 1.0, 1.0],
                                                                     [1.0, 1.0, 1.0, 0.0]
                                                                   ]
  args.state.max_swing_angle ||= 45

  if args.state.swinging_light_start_at.elapsed_time > args.state.swinging_light_duration
    args.state.swinging_light_start_at = args.state.tick_count
    args.state.swinging_light_sign *= -1
  end

  args.state.swinging_light_angle = 360 + ((args.state.max_swing_angle * args.state.swinging_light_perc) * args.state.swinging_light_sign)
end

def render args
  args.outputs.background_color = [0, 0, 0]

  # render scene
  args.outputs[:scene].transient!
  args.outputs[:scene].sprites << { x:        0, y:   0, w: 1280, h: 720, path: :pixel }
  args.outputs[:scene].sprites << { x: 640 - 40, y: 100, w:   80, h:  80, path: 'sprites/square/blue.png' }
  args.outputs[:scene].sprites << { x: 640 - 40, y: 200, w:   80, h:  80, path: 'sprites/square/blue.png' }
  args.outputs[:scene].sprites << { x: 640 - 40, y: 300, w:   80, h:  80, path: 'sprites/square/blue.png' }
  args.outputs[:scene].sprites << { x: 640 - 40, y: 400, w:   80, h:  80, path: 'sprites/square/blue.png' }
  args.outputs[:scene].sprites << { x: 640 - 40, y: 500, w:   80, h:  80, path: 'sprites/square/blue.png' }

  # render light
  swinging_light_w = 1100
  args.outputs[:lights].transient!
  args.outputs[:lights].background_color = [0, 0, 0, 0]
  args.outputs[:lights].sprites << { x: 640 - swinging_light_w.half,
                                     y: -1300,
                                     w: swinging_light_w,
                                     h: 3000,
                                     angle_anchor_x: 0.5,
                                     angle_anchor_y: 1.0,
                                     path: "sprites/lights/mask.png",
                                     angle: args.state.swinging_light_angle }

  args.outputs[:lights].sprites << { x: args.inputs.mouse.x - 400,
                                     y: args.inputs.mouse.y - 400,
                                     w: 800,
                                     h: 800,
                                     path: "sprites/lights/mask.png" }

  # merge unlighted scene with lights
  args.outputs[:lighted_scene].transient!
  args.outputs[:lighted_scene].sprites << { x: 0, y: 0, w: 1280, h: 720, path: :lights, blendmode_enum: 0 }
  args.outputs[:lighted_scene].sprites << { blendmode_enum: 2, x: 0, y: 0, w: 1280, h: 720, path: :scene }

  # output lighted scene to main canvas
  args.outputs.sprites << { x: 0, y: 0, w: 1280, h: 720, path: :lighted_scene }

  # render lights and scene render_targets as a mini map
  args.outputs.debug  << { x: 16,      y: (16 + 90).from_top, w: 160, h: 90, r: 255, g: 255, b: 255 }.solid!
  args.outputs.debug  << { x: 16,      y: (16 + 90).from_top, w: 160, h: 90, path: :lights }
  args.outputs.debug  << { x: 16 + 80, y: (16 + 90 + 8).from_top, text: ":lights render_target", r: 255, g: 255, b: 255, size_enum: -3, alignment_enum: 1 }

  args.outputs.debug  << { x: 16 + 160 + 16,      y: (16 + 90).from_top, w: 160, h: 90, r: 255, g: 255, b: 255 }.solid!
  args.outputs.debug  << { x: 16 + 160 + 16,      y: (16 + 90).from_top, w: 160, h: 90, path: :scene }
  args.outputs.debug  << { x: 16 + 160 + 16 + 80, y: (16 + 90 + 8).from_top, text: ":scene render_target", r: 255, g: 255, b: 255, size_enum: -3, alignment_enum: 1 }
end

def tick args
  render args
  calc args
end

$gtk.reset

    Triangles - main.rb link

    # ./samples/07_advanced_rendering/14_triangles/app/main.rb
def tick args
  args.outputs.labels << {
    x: 640,
    y: 30.from_top,
    text: "Triangle rendering is available in Indie and Pro versions (ignored in Standard Edition).",
    alignment_enum: 1
  }

  dragonruby_logo_width  = 128
  dragonruby_logo_height = 101

  row_0 = 400
  row_1 = 250

  col_0 = 384 - dragonruby_logo_width.half + dragonruby_logo_width * 0
  col_1 = 384 - dragonruby_logo_width.half + dragonruby_logo_width * 1
  col_2 = 384 - dragonruby_logo_width.half + dragonruby_logo_width * 2
  col_3 = 384 - dragonruby_logo_width.half + dragonruby_logo_width * 3
  col_4 = 384 - dragonruby_logo_width.half + dragonruby_logo_width * 4

  # row 0
  args.outputs.solids << make_triangle(
    col_0,
    row_0,
    col_0 + dragonruby_logo_width.half,
    row_0 + dragonruby_logo_height,
    col_0 + dragonruby_logo_width.half + dragonruby_logo_width.half,
    row_0,
    0, 128, 128,
    128
  )

  args.outputs.solids << {
    x:  col_1,
    y:  row_0,
    x2: col_1 + dragonruby_logo_width.half,
    y2: row_0 + dragonruby_logo_height,
    x3: col_1 + dragonruby_logo_width,
    y3: row_0,
  }

  args.outputs.sprites << {
    x:  col_2,
    y:  row_0,
    w:  dragonruby_logo_width,
    h:  dragonruby_logo_height,
    path: 'dragonruby.png'
  }

  args.outputs.sprites << {
    x:  col_3,
    y:  row_0,
    x2: col_3 + dragonruby_logo_width.half,
    y2: row_0 + dragonruby_logo_height,
    x3: col_3 + dragonruby_logo_width,
    y3: row_0,
    path: 'dragonruby.png',
    source_x:  0,
    source_y:  0,
    source_x2: dragonruby_logo_width.half,
    source_y2: dragonruby_logo_height,
    source_x3: dragonruby_logo_width,
    source_y3: 0
  }

  args.outputs.sprites << TriangleLogo.new(x:  col_4,
                                           y:  row_0,
                                           x2: col_4 + dragonruby_logo_width.half,
                                           y2: row_0 + dragonruby_logo_height,
                                           x3: col_4 + dragonruby_logo_width,
                                           y3: row_0,
                                           path: 'dragonruby.png',
                                           source_x:  0,
                                           source_y:  0,
                                           source_x2: dragonruby_logo_width.half,
                                           source_y2: dragonruby_logo_height,
                                           source_x3: dragonruby_logo_width,
                                           source_y3: 0)

  # row 1
  args.outputs.primitives << make_triangle(
    col_0,
    row_1,
    col_0 + dragonruby_logo_width.half,
    row_1 + dragonruby_logo_height,
    col_0 + dragonruby_logo_width,
    row_1,
    0, 128, 128,
    args.state.tick_count.to_radians.sin_r.abs * 255
  )

  args.outputs.primitives << {
    x:  col_1,
    y:  row_1,
    x2: col_1 + dragonruby_logo_width.half,
    y2: row_1 + dragonruby_logo_height,
    x3: col_1 + dragonruby_logo_width,
    y3: row_1,
    r:  0, g: 0, b: 0, a: args.state.tick_count.to_radians.sin_r.abs * 255
  }

  args.outputs.sprites << {
    x:  col_2,
    y:  row_1,
    w:  dragonruby_logo_width,
    h:  dragonruby_logo_height,
    path: 'dragonruby.png',
    source_x:  0,
    source_y:  0,
    source_w:  dragonruby_logo_width,
    source_h:  dragonruby_logo_height.half +
               dragonruby_logo_height.half * Math.sin(args.state.tick_count.to_radians).abs,
  }

  args.outputs.primitives << {
    x:  col_3,
    y:  row_1,
    x2: col_3 + dragonruby_logo_width.half,
    y2: row_1 + dragonruby_logo_height,
    x3: col_3 + dragonruby_logo_width,
    y3: row_1,
    path: 'dragonruby.png',
    source_x:  0,
    source_y:  0,
    source_x2: dragonruby_logo_width.half,
    source_y2: dragonruby_logo_height.half +
               dragonruby_logo_height.half * Math.sin(args.state.tick_count.to_radians).abs,
    source_x3: dragonruby_logo_width,
    source_y3: 0
  }

  args.outputs.primitives << TriangleLogo.new(x:  col_4,
                                              y:  row_1,
                                              x2: col_4 + dragonruby_logo_width.half,
                                              y2: row_1 + dragonruby_logo_height,
                                              x3: col_4 + dragonruby_logo_width,
                                              y3: row_1,
                                              path: 'dragonruby.png',
                                              source_x:  0,
                                              source_y:  0,
                                              source_x2: dragonruby_logo_width.half,
                                              source_y2: dragonruby_logo_height.half +
                                                         dragonruby_logo_height.half * Math.sin(args.state.tick_count.to_radians).abs,
                                              source_x3: dragonruby_logo_width,
                                              source_y3: 0)
end

def make_triangle *opts
  x, y, x2, y2, x3, y3, r, g, b, a = opts
  {
    x: x, y: y, x2: x2, y2: y2, x3: x3, y3: y3,
    r: r || 0,
    g: g || 0,
    b: b || 0,
    a: a || 255
  }
end

class TriangleLogo
  attr_sprite

  def initialize x:, y:, x2:, y2:, x3:, y3:, path:, source_x:, source_y:, source_x2:, source_y2:, source_x3:, source_y3:;
    @x         = x
    @y         = y
    @x2        = x2
    @y2        = y2
    @x3        = x3
    @y3        = y3
    @path      = path
    @source_x  = source_x
    @source_y  = source_y
    @source_x2 = source_x2
    @source_y2 = source_y2
    @source_x3 = source_x3
    @source_y3 = source_y3
  end
end

    Triangles Trapezoid - main.rb link

    # ./samples/07_advanced_rendering/15_triangles_trapezoid/app/main.rb
def tick args
  args.outputs.labels << {
    x: 640,
    y: 30.from_top,
    text: "Triangle rendering is available in Indie and Pro versions (ignored in Standard Edition).",
    alignment_enum: 1
  }

  transform_scale = ((args.state.tick_count / 3).sin.abs ** 5).half
  args.outputs.sprites << [
    { x:         600,
      y:         320,
      x2:        600,
      y2:        400,
      x3:        640,
      y3:        360,
      path:      "sprites/square/blue.png",
      source_x:  0,
      source_y:  0,
      source_x2: 0,
      source_y2: 80,
      source_x3: 40,
      source_y3: 40 },
    { x:         600,
      y:         400,
      x2:        680,
      y2:        (400 - 80 * transform_scale).round,
      x3:        640,
      y3:        360,
      path:      "sprites/square/blue.png",
      source_x:  0,
      source_y:  80,
      source_x2: 80,
      source_y2: 80,
      source_x3: 40,
      source_y3: 40 },
    { x:         640,
      y:         360,
      x2:        680,
      y2:        (400 - 80 * transform_scale).round,
      x3:        680,
      y3:        (320 + 80 * transform_scale).round,
      path:      "sprites/square/blue.png",
      source_x:  40,
      source_y:  40,
      source_x2: 80,
      source_y2: 80,
      source_x3: 80,
      source_y3: 0 },
    { x:         600,
      y:         320,
      x2:        640,
      y2:        360,
      x3:        680,
      y3:        (320 + 80 * transform_scale).round,
      path:      "sprites/square/blue.png",
      source_x:  0,
      source_y:  0,
      source_x2: 40,
      source_y2: 40,
      source_x3: 80,
      source_y3: 0 }
  ]
end

    Camera Space World Space Simple - main.rb link

    # ./samples/07_advanced_rendering/16_camera_space_world_space_simple/app/main.rb
def tick args
  # camera must have the following properties (x, y, and scale)
  args.state.camera ||= {
    x: 0,
    y: 0,
    scale: 1
  }

  args.state.camera.x += args.inputs.left_right * 10 * args.state.camera.scale
  args.state.camera.y += args.inputs.up_down * 10 * args.state.camera.scale

  # generate 500 shapes with random positions
  args.state.objects ||= 500.map do
    {
      x: -2000 + rand(4000),
      y: -2000 + rand(4000),
      w: 16,
      h: 16,
      path: 'sprites/square/blue.png'
    }
  end

  # "i" to zoom in, "o" to zoom out
  if args.inputs.keyboard.key_down.i || args.inputs.keyboard.key_down.equal_sign || args.inputs.keyboard.key_down.plus
    args.state.camera.scale += 0.1
  elsif args.inputs.keyboard.key_down.o || args.inputs.keyboard.key_down.minus
    args.state.camera.scale -= 0.1
    args.state.camera.scale = 0.1 if args.state.camera.scale < 0.1
  end

  # "zero" to reset zoom and camera
  if args.inputs.keyboard.key_down.zero
    args.state.camera.scale = 1
    args.state.camera.x = 0
    args.state.camera.y = 0
  end

  # if mouse is clicked
  if args.inputs.mouse.click
    # convert the mouse to world space and delete any objects that intersect with the mouse
    rect = Camera.to_world_space args.state.camera, args.inputs.mouse
    args.state.objects.reject! { |o| rect.intersect_rect? o }
  end

  # "r" to reset
  if args.inputs.keyboard.key_down.r
    $gtk.reset_next_tick
  end

  # define scene
  args.outputs[:scene].transient!
  args.outputs[:scene].w = Camera::WORLD_SIZE
  args.outputs[:scene].h = Camera::WORLD_SIZE

  # render diagonals and background of scene
  args.outputs[:scene].lines << { x: 0, y: 0, x2: 1500, y2: 1500, r: 0, g: 0, b: 0, a: 255 }
  args.outputs[:scene].lines << { x: 0, y: 1500, x2: 1500, y2: 0, r: 0, g: 0, b: 0, a: 255 }
  args.outputs[:scene].solids << { x: 0, y: 0, w: 1500, h: 1500, a: 128 }

  # find all objects to render
  objects_to_render = Camera.find_all_intersect_viewport args.state.camera, args.state.objects

  # for objects that were found, convert the rect to screen coordinates and place them in scene
  args.outputs[:scene].sprites << objects_to_render.map { |o| Camera.to_screen_space args.state.camera, o }

  # render scene to screen
  args.outputs.sprites << { **Camera.viewport, path: :scene }

  # render instructions
  args.outputs.sprites << { x: 0, y: 110.from_top, w: 1280, h: 110, path: :pixel, r: 0, g: 0, b: 0, a: 128 }
  label_style = { r: 255, g: 255, b: 255, anchor_y: 0.5 }
  args.outputs.labels << { x: 30, y: 30.from_top, text: "Arrow keys to move around. I and O Keys to zoom in and zoom out (0 to reset camera, R to reset everything).", **label_style }
  args.outputs.labels << { x: 30, y: 60.from_top, text: "Click square to remove from world.", **label_style }
  args.outputs.labels << { x: 30, y: 90.from_top, text: "Mouse locationin world: #{(Camera.to_world_space args.state.camera, args.inputs.mouse).to_sf}", **label_style }
end

# helper methods to create a camera and go to and from screen space and world space
class Camera
  SCREEN_WIDTH = 1280
  SCREEN_HEIGHT = 720
  WORLD_SIZE = 1500
  WORLD_SIZE_HALF = WORLD_SIZE / 2
  OFFSET_X = (SCREEN_WIDTH - WORLD_SIZE) / 2
  OFFSET_Y = (SCREEN_HEIGHT - WORLD_SIZE) / 2

  class << self
    # given a rect in screen space, converts the rect to world space
    def to_world_space camera, rect
      rect_x = rect.x
      rect_y = rect.y
      rect_w = rect.w || 0
      rect_h = rect.h || 0
      x = (rect_x - WORLD_SIZE_HALF + camera.x * camera.scale - OFFSET_X) / camera.scale
      y = (rect_y - WORLD_SIZE_HALF + camera.y * camera.scale - OFFSET_Y) / camera.scale
      w = rect_w / camera.scale
      h = rect_h / camera.scale
      rect.merge x: x, y: y, w: w, h: h
    end

    # given a rect in world space, converts the rect to screen space
    def to_screen_space camera, rect
      rect_x = rect.x
      rect_y = rect.y
      rect_w = rect.w || 0
      rect_h = rect.h || 0
      x = rect_x * camera.scale - camera.x * camera.scale + WORLD_SIZE_HALF
      y = rect_y * camera.scale - camera.y * camera.scale + WORLD_SIZE_HALF
      w = rect_w * camera.scale
      h = rect_h * camera.scale
      rect.merge x: x, y: y, w: w, h: h
    end

    # viewport of the scene
    def viewport
      {
        x: OFFSET_X,
        y: OFFSET_Y,
        w: 1500,
        h: 1500
      }
    end

    # viewport in the context of the world
    def viewport_world camera
      to_world_space camera, viewport
    end

    # helper method to find objects within viewport
    def find_all_intersect_viewport camera, os
      Geometry.find_all_intersect_rect viewport_world(camera), os
    end
  end
end

$gtk.reset

    Camera Space World Space Simple Grid Map - main.rb link

    # ./samples/07_advanced_rendering/16_camera_space_world_space_simple_grid_map/app/main.rb
def tick args
  defaults args
  calc args
  render args
end

def defaults args
  tile_size = 100
  tiles_per_row = 32
  number_of_rows = 32
  number_of_tiles = tiles_per_row * number_of_rows

  # generate map tiles
  args.state.tiles ||= number_of_tiles.map_with_index do |i|
    row = i.idiv(tiles_per_row)
    col = i.mod(tiles_per_row)
    {
      x: row * tile_size,
      y: col * tile_size,
      w: tile_size,
      h: tile_size,
      path: 'sprites/square/blue.png'
    }
  end

  center_map = {
    x: tiles_per_row.idiv(2) * tile_size,
    y: number_of_rows.idiv(2) * tile_size,
    w: 1,
    h: 1
  }

  args.state.center_tile ||= args.state.tiles.find { |o| o.intersect_rect? center_map }
  args.state.selected_tile ||= args.state.center_tile

  # camera must have the following properties (x, y, and scale)
  if !args.state.camera
    args.state.camera = {
      x: 0,
      y: 0,
      scale: 1,
      target_x: 0,
      target_y: 0,
      target_scale: 1
    }

    args.state.camera.target_x = args.state.selected_tile.x + args.state.selected_tile.w.half
    args.state.camera.target_y = args.state.selected_tile.y + args.state.selected_tile.h.half
    args.state.camera.x = args.state.camera.target_x
    args.state.camera.y = args.state.camera.target_y
  end
end

def calc args
  calc_inputs args
  calc_camera args
end

def calc_inputs args
  # "i" to zoom in, "o" to zoom out
  if args.inputs.keyboard.key_down.i || args.inputs.keyboard.key_down.equal_sign || args.inputs.keyboard.key_down.plus
    args.state.camera.target_scale += 0.1 * args.state.camera.scale
  elsif args.inputs.keyboard.key_down.o || args.inputs.keyboard.key_down.minus
    args.state.camera.target_scale -= 0.1 * args.state.camera.scale
    args.state.camera.target_scale = 0.1 if args.state.camera.scale < 0.1
  end

  # "zero" to reset zoom and camera
  if args.inputs.keyboard.key_down.zero
    args.state.camera.target_scale = 1
    args.state.selected_tile = args.state.center_tile
  end

  # if mouse is clicked
  if args.inputs.mouse.click
    # convert the mouse to world space and delete any tiles that intersect with the mouse
    rect = Camera.to_world_space args.state.camera, args.inputs.mouse
    selected_tile = args.state.tiles.find { |o| rect.intersect_rect? o }
    if selected_tile
      args.state.selected_tile = selected_tile
      args.state.camera.target_scale = 1
    end
  end

  # "r" to reset
  if args.inputs.keyboard.key_down.r
    $gtk.reset_next_tick
  end
end

def calc_camera args
  args.state.camera.target_x = args.state.selected_tile.x + args.state.selected_tile.w.half
  args.state.camera.target_y = args.state.selected_tile.y + args.state.selected_tile.h.half
  dx = args.state.camera.target_x - args.state.camera.x
  dy = args.state.camera.target_y - args.state.camera.y
  ds = args.state.camera.target_scale - args.state.camera.scale
  args.state.camera.x += dx * 0.1 * args.state.camera.scale
  args.state.camera.y += dy * 0.1 * args.state.camera.scale
  args.state.camera.scale += ds * 0.1
end

def render args
  args.outputs.background_color = [0, 0, 0]

  # define scene
  args.outputs[:scene].transient!
  args.outputs[:scene].w = Camera::WORLD_SIZE
  args.outputs[:scene].h = Camera::WORLD_SIZE
  args.outputs[:scene].background_color = [0, 0, 0, 0]

  # render diagonals and background of scene
  args.outputs[:scene].lines << { x: 0, y: 0, x2: 1500, y2: 1500, r: 0, g: 0, b: 0, a: 255 }
  args.outputs[:scene].lines << { x: 0, y: 1500, x2: 1500, y2: 0, r: 0, g: 0, b: 0, a: 255 }
  args.outputs[:scene].solids << { x: 0, y: 0, w: 1500, h: 1500, a: 128 }

  # find all tiles to render
  objects_to_render = Camera.find_all_intersect_viewport args.state.camera, args.state.tiles

  # convert mouse to world space to see if it intersects with any tiles (hover color)
  mouse_in_world = Camera.to_world_space args.state.camera, args.inputs.mouse

  # for tiles that were found, convert the rect to screen coordinates and place them in scene
  args.outputs[:scene].sprites << objects_to_render.map do |o|
    if o == args.state.selected_tile
      tile_to_render = o.merge path: 'sprites/square/green.png'
    elsif o.intersect_rect? mouse_in_world
      tile_to_render = o.merge path: 'sprites/square/orange.png'
    else
      tile_to_render = o.merge path: 'sprites/square/blue.png'
    end

    Camera.to_screen_space args.state.camera, tile_to_render
  end

  # render scene to screen
  args.outputs.sprites << { **Camera.viewport, path: :scene }

  # render instructions
  args.outputs.sprites << { x: 0, y: 110.from_top, w: 1280, h: 110, path: :pixel, r: 0, g: 0, b: 0, a: 200 }
  label_style = { r: 255, g: 255, b: 255, anchor_y: 0.5 }
  args.outputs.labels << { x: 30, y: 30.from_top, text: "I/O or +/- keys to zoom in and zoom out (0 to reset camera, R to reset everything).", **label_style }
  args.outputs.labels << { x: 30, y: 60.from_top, text: "Click to center on square.", **label_style }
  args.outputs.labels << { x: 30, y: 90.from_top, text: "Mouse location in world: #{(Camera.to_world_space args.state.camera, args.inputs.mouse).to_sf}", **label_style }
end

# helper methods to create a camera and go to and from screen space and world space
class Camera
  SCREEN_WIDTH = 1280
  SCREEN_HEIGHT = 720
  WORLD_SIZE = 1500
  WORLD_SIZE_HALF = WORLD_SIZE / 2
  OFFSET_X = (SCREEN_WIDTH - WORLD_SIZE) / 2
  OFFSET_Y = (SCREEN_HEIGHT - WORLD_SIZE) / 2

  class << self
    # given a rect in screen space, converts the rect to world space
    def to_world_space camera, rect
      rect_x = rect.x
      rect_y = rect.y
      rect_w = rect.w || 0
      rect_h = rect.h || 0
      x = (rect_x - WORLD_SIZE_HALF + camera.x * camera.scale - OFFSET_X) / camera.scale
      y = (rect_y - WORLD_SIZE_HALF + camera.y * camera.scale - OFFSET_Y) / camera.scale
      w = rect_w / camera.scale
      h = rect_h / camera.scale
      rect.merge x: x, y: y, w: w, h: h
    end

    # given a rect in world space, converts the rect to screen space
    def to_screen_space camera, rect
      rect_x = rect.x
      rect_y = rect.y
      rect_w = rect.w || 0
      rect_h = rect.h || 0
      x = rect_x * camera.scale - camera.x * camera.scale + WORLD_SIZE_HALF
      y = rect_y * camera.scale - camera.y * camera.scale + WORLD_SIZE_HALF
      w = rect_w * camera.scale
      h = rect_h * camera.scale
      rect.merge x: x, y: y, w: w, h: h
    end

    # viewport of the scene
    def viewport
      {
        x: OFFSET_X,
        y: OFFSET_Y,
        w: WORLD_SIZE,
        h: WORLD_SIZE
      }
    end

    # viewport in the context of the world
    def viewport_world camera
      to_world_space camera, viewport
    end

    # helper method to find objects within viewport
    def find_all_intersect_viewport camera, os
      Geometry.find_all_intersect_rect viewport_world(camera), os
    end
  end
end

$gtk.reset

    Matrix And Triangles 2d - main.rb link

    # ./samples/07_advanced_rendering/16_matrix_and_triangles_2d/app/main.rb
include MatrixFunctions

def tick args
  args.state.square_one_sprite = { x:        0,
                                   y:        0,
                                   w:        100,
                                   h:        100,
                                   path:     "sprites/square/blue.png",
                                   source_x: 0,
                                   source_y: 0,
                                   source_w: 80,
                                   source_h: 80 }

  args.state.square_two_sprite = { x:        0,
                                   y:        0,
                                   w:        100,
                                   h:        100,
                                   path:     "sprites/square/red.png",
                                   source_x: 0,
                                   source_y: 0,
                                   source_w: 80,
                                   source_h: 80 }

  args.state.square_one        = sprite_to_triangles args.state.square_one_sprite
  args.state.square_two        = sprite_to_triangles args.state.square_two_sprite
  args.state.camera.x        ||= 0
  args.state.camera.y        ||= 0
  args.state.camera.zoom     ||= 1
  args.state.camera.rotation ||= 0

  zmod = 1
  move_multiplier = 1
  dzoom = 0.01

  if args.state.tick_count.zmod? zmod
    args.state.camera.x += args.inputs.left_right * -1 * move_multiplier
    args.state.camera.y += args.inputs.up_down * -1 * move_multiplier
  end

  if args.inputs.keyboard.i
    args.state.camera.zoom += dzoom
  elsif args.inputs.keyboard.o
    args.state.camera.zoom -= dzoom
  end

  args.state.camera.zoom = args.state.camera.zoom.clamp(0.25, 10)

  args.outputs.sprites << triangles_mat3_mul(args.state.square_one,
                                             mat3_translate(-50, -50),
                                             mat3_rotate(args.state.tick_count),
                                             mat3_translate(0, 0),
                                             mat3_translate(args.state.camera.x, args.state.camera.y),
                                             mat3_scale(args.state.camera.zoom),
                                             mat3_translate(640, 360))

  args.outputs.sprites << triangles_mat3_mul(args.state.square_two,
                                             mat3_translate(-50, -50),
                                             mat3_rotate(args.state.tick_count),
                                             mat3_translate(100, 100),
                                             mat3_translate(args.state.camera.x, args.state.camera.y),
                                             mat3_scale(args.state.camera.zoom),
                                             mat3_translate(640, 360))

  mouse_coord = vec3 args.inputs.mouse.x,
                     args.inputs.mouse.y,
                     1

  mouse_coord = mul mouse_coord,
                    mat3_translate(-640, -360),
                    mat3_scale(args.state.camera.zoom),
                    mat3_translate(-args.state.camera.x, -args.state.camera.y)

  args.outputs.lines  << { x: 640, y:   0, h:  720 }
  args.outputs.lines  << { x:   0, y: 360, w: 1280 }
  args.outputs.labels << { x: 30, y: 60.from_top, text: "x: #{args.state.camera.x.to_sf} y: #{args.state.camera.y.to_sf} z: #{args.state.camera.zoom.to_sf}" }
  args.outputs.labels << { x: 30, y: 90.from_top, text: "Mouse: #{mouse_coord.x.to_sf} #{mouse_coord.y.to_sf}" }
  args.outputs.labels << { x: 30,
                           y: 30.from_top,
                           text: "W,A,S,D to move. I, O to zoom. Triangles is a Indie/Pro Feature and will be ignored in Standard." }
end

def sprite_to_triangles sprite
  [
    {
      x:         sprite.x,                          y:  sprite.y,
      x2:        sprite.x,                          y2: sprite.y + sprite.h,
      x3:        sprite.x + sprite.w,               y3: sprite.y + sprite.h,
      source_x:  sprite.source_x,                   source_y:  sprite.source_y,
      source_x2: sprite.source_x,                   source_y2: sprite.source_y + sprite.source_h,
      source_x3: sprite.source_x + sprite.source_w, source_y3: sprite.source_y + sprite.source_h,
      path:      sprite.path
    },
    {
      x:  sprite.x,                                 y:  sprite.y,
      x2: sprite.x + sprite.w,                      y2: sprite.y + sprite.h,
      x3: sprite.x + sprite.w,                      y3: sprite.y,
      source_x:  sprite.source_x,                   source_y:  sprite.source_y,
      source_x2: sprite.source_x + sprite.source_w, source_y2: sprite.source_y + sprite.source_h,
      source_x3: sprite.source_x + sprite.source_w, source_y3: sprite.source_y,
      path:      sprite.path
    }
  ]
end

def mat3_translate dx, dy
  mat3 1, 0, dx,
       0, 1, dy,
       0, 0,  1
end

def mat3_rotate angle_d
  angle_r = angle_d.to_radians
  mat3 Math.cos(angle_r), -Math.sin(angle_r), 0,
       Math.sin(angle_r),  Math.cos(angle_r), 0,
                       0,                  0, 1
end

def mat3_scale scale
  mat3 scale,     0, 0,
           0, scale, 0,
           0,     0, 1
end

def triangles_mat3_mul triangles, *matrices
  triangles.map { |triangle| triangle_mat3_mul triangle, *matrices }
end

def triangle_mat3_mul triangle, *matrices
  result = [
    (vec3 triangle.x,  triangle.y,  1),
    (vec3 triangle.x2, triangle.y2, 1),
    (vec3 triangle.x3, triangle.y3, 1)
  ].map do |coord|
    mul coord, *matrices
  end

  {
    **triangle,
    x:  result[0].x,
    y:  result[0].y,
    x2: result[1].x,
    y2: result[1].y,
    x3: result[2].x,
    y3: result[2].y,
  }
rescue Exception => e
  pretty_print triangle
  pretty_print result
  pretty_print matrices
  puts "#{matrices}"
  raise e
end

    Matrix And Triangles 3d - main.rb link

    # ./samples/07_advanced_rendering/16_matrix_and_triangles_3d/app/main.rb
include MatrixFunctions

def tick args
  args.outputs.labels << { x: 0,
                           y: 30.from_top,
                           text: "W,A,S,D to move. Q,E,U,O to turn, I,K for elevation. Triangles is a Indie/Pro Feature and will be ignored in Standard.",
                           alignment_enum: 1 }

  args.grid.origin_center!

  args.state.cam_x ||= 0.00
  if args.inputs.keyboard.left
    args.state.cam_x += 0.01
  elsif args.inputs.keyboard.right
    args.state.cam_x -= 0.01
  end

  args.state.cam_y ||= 0.00
  if args.inputs.keyboard.i
    args.state.cam_y += 0.01
  elsif args.inputs.keyboard.k
    args.state.cam_y -= 0.01
  end

  args.state.cam_z ||= 6.5
  if args.inputs.keyboard.s
    args.state.cam_z += 0.1
  elsif args.inputs.keyboard.w
    args.state.cam_z -= 0.1
  end

  args.state.cam_angle_y ||= 0
  if args.inputs.keyboard.q
    args.state.cam_angle_y += 0.25
  elsif args.inputs.keyboard.e
    args.state.cam_angle_y -= 0.25
  end

  args.state.cam_angle_x ||= 0
  if args.inputs.keyboard.u
    args.state.cam_angle_x += 0.1
  elsif args.inputs.keyboard.o
    args.state.cam_angle_x -= 0.1
  end

  # model A
  args.state.a = [
    [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
    [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
  ]

  # model to world
  args.state.a_world = mul_world args,
                                 args.state.a,
                                 (translate -0.25, -0.25, 0),
                                 (translate  0, 0, 0.25),
                                 (rotate_x args.state.tick_count)

  args.state.a_camera = mul_cam args, args.state.a_world
  args.state.a_projected = mul_perspective args, args.state.a_camera
  render_projection args, args.state.a_projected

  # model B
  args.state.b = [
    [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
    [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
  ]

  # model to world
  args.state.b_world = mul_world args,
                                 args.state.b,
                                 (translate -0.25, -0.25, 0),
                                 (translate  0, 0, -0.25),
                                 (rotate_x args.state.tick_count)

  args.state.b_camera = mul_cam args, args.state.b_world
  args.state.b_projected = mul_perspective args, args.state.b_camera
  render_projection args, args.state.b_projected

  # model C
  args.state.c = [
    [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
    [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
  ]

  # model to world
  args.state.c_world = mul_world args,
                                 args.state.c,
                                 (translate -0.25, -0.25, 0),
                                 (rotate_y 90),
                                 (translate -0.25,  0, 0),
                                 (rotate_x args.state.tick_count)

  args.state.c_camera = mul_cam args, args.state.c_world
  args.state.c_projected = mul_perspective args, args.state.c_camera
  render_projection args, args.state.c_projected

  # model D
  args.state.d = [
    [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
    [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
  ]

  # model to world
  args.state.d_world = mul_world args,
                                 args.state.d,
                                 (translate -0.25, -0.25, 0),
                                 (rotate_y 90),
                                 (translate  0.25,  0, 0),
                                 (rotate_x args.state.tick_count)

  args.state.d_camera = mul_cam args, args.state.d_world
  args.state.d_projected = mul_perspective args, args.state.d_camera
  render_projection args, args.state.d_projected

  # model E
  args.state.e = [
    [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
    [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
  ]

  # model to world
  args.state.e_world = mul_world args,
                                 args.state.e,
                                 (translate -0.25, -0.25, 0),
                                 (rotate_x 90),
                                 (translate  0,  0.25, 0),
                                 (rotate_x args.state.tick_count)

  args.state.e_camera = mul_cam args, args.state.e_world
  args.state.e_projected = mul_perspective args, args.state.e_camera
  render_projection args, args.state.e_projected

  # model E
  args.state.f = [
    [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
    [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
  ]

  # model to world
  args.state.f_world = mul_world args,
                                 args.state.f,
                                 (translate -0.25, -0.25, 0),
                                 (rotate_x 90),
                                 (translate  0,  -0.25, 0),
                                 (rotate_x args.state.tick_count)

  args.state.f_camera = mul_cam args, args.state.f_world
  args.state.f_projected = mul_perspective args, args.state.f_camera
  render_projection args, args.state.f_projected

  # render_debug args, args.state.a, args.state.a_transform, args.state.a_projected
  # args.outputs.labels << { x: -630, y:  10.from_top,  text: "x:         #{args.state.cam_x.to_sf} -> #{( args.state.cam_x * 1000 ).to_sf}" }
  # args.outputs.labels << { x: -630, y:  30.from_top,  text: "y:         #{args.state.cam_y.to_sf} -> #{( args.state.cam_y * 1000 ).to_sf}" }
  # args.outputs.labels << { x: -630, y:  50.from_top,  text: "z:         #{args.state.cam_z.fdiv(10).to_sf} -> #{( args.state.cam_z * 100 ).to_sf}" }
end

def mul_world args, model, *mul_def
  model.map do |vecs|
    vecs.map do |vec|
      mul vec,
          *mul_def
    end
  end
end

def mul_cam args, world_vecs
  world_vecs.map do |vecs|
    vecs.map do |vec|
      mul vec,
          (translate -args.state.cam_x, args.state.cam_y, -args.state.cam_z),
          (rotate_y args.state.cam_angle_y),
          (rotate_x args.state.cam_angle_x)
    end
  end
end

def mul_perspective args, camera_vecs
  camera_vecs.map do |vecs|
    vecs.map do |vec|
      perspective vec
    end
  end
end

def render_debug args, model, transform, projected
  args.outputs.labels << { x: -630, y:  10.from_top,  text: "model:     #{vecs_to_s model[0]}" }
  args.outputs.labels << { x: -630, y:  30.from_top,  text: "           #{vecs_to_s model[1]}" }
  args.outputs.labels << { x: -630, y:  50.from_top,  text: "transform: #{vecs_to_s transform[0]}" }
  args.outputs.labels << { x: -630, y:  70.from_top,  text: "           #{vecs_to_s transform[1]}" }
  args.outputs.labels << { x: -630, y:  90.from_top,  text: "projected: #{vecs_to_s projected[0]}" }
  args.outputs.labels << { x: -630, y: 110.from_top,  text: "           #{vecs_to_s projected[1]}" }
end

def render_projection args, projection
  p0 = projection[0]
  args.outputs.sprites << {
    x:  p0[0].x,   y: p0[0].y,
    x2: p0[1].x,  y2: p0[1].y,
    x3: p0[2].x,  y3: p0[2].y,
    source_x:   0, source_y:   0,
    source_x2: 80, source_y2:  0,
    source_x3:  0, source_y3: 80,
    a: 40,
    # r: 128, g: 128, b: 128,
    path: 'sprites/square/blue.png'
  }

  p1 = projection[1]
  args.outputs.sprites << {
    x:  p1[0].x,   y: p1[0].y,
    x2: p1[1].x,  y2: p1[1].y,
    x3: p1[2].x,  y3: p1[2].y,
    source_x:  80, source_y:   0,
    source_x2: 80, source_y2: 80,
    source_x3:  0, source_y3: 80,
    a: 40,
    # r: 128, g: 128, b: 128,
    path: 'sprites/square/blue.png'
  }
end

def perspective vec
  left   = -1.0
  right  =  1.0
  bottom = -1.0
  top    =  1.0
  near   =  300.0
  far    =  1000.0
  sx = 2 * near / (right - left)
  sy = 2 * near / (top - bottom)
  c2 = - (far + near) / (far - near)
  c1 = 2 * near * far / (near - far)
  tx = -near * (left + right) / (right - left)
  ty = -near * (bottom + top) / (top - bottom)

  p = mat4 sx, 0, 0, tx,
           0, sy, 0, ty,
           0, 0, c2, c1,
           0, 0, -1, 0

  r = mul vec, p
  r.x *= r.z / r.w / 100
  r.y *= r.z / r.w / 100
  r
end

def mat_scale scale
  mat4 scale,     0,     0,   0,
           0, scale,     0,   0,
           0,     0, scale,   0,
           0,     0,     0,   1
end

def rotate_y angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  (mat4  cos_t,  0, sin_t, 0,
         0,      1, 0,     0,
         -sin_t, 0, cos_t, 0,
         0,      0, 0,     1)
end

def rotate_z angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  (mat4 cos_t, -sin_t, 0, 0,
        sin_t,  cos_t, 0, 0,
        0,      0,     1, 0,
        0,      0,     0, 1)
end

def translate dx, dy, dz
  mat4 1, 0, 0, dx,
       0, 1, 0, dy,
       0, 0, 1, dz,
       0, 0, 0,  1
end


def rotate_x angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  (mat4  1,     0,      0, 0,
         0, cos_t, -sin_t, 0,
         0, sin_t,  cos_t, 0,
         0,     0,      0, 1)
end

def vecs_to_s vecs
  vecs.map do |vec|
    "[#{vec.x.to_sf} #{vec.y.to_sf} #{vec.z.to_sf}]"
  end.join " "
end

    Matrix Camera Space World Space - main.rb link

    # ./samples/07_advanced_rendering/16_matrix_camera_space_world_space/app/main.rb
# sample app shows how to translate between screen and world coordinates using matrix multiplication
class Game
  attr_gtk

  def tick
    defaults
    input
    calc
    render
  end

  def defaults
    return if state.tick_count != 0

    # define the size of the world
    state.world_size = 1280

    # initialize the camera
    state.camera = {
      x: 0,
      y: 0,
      zoom: 1
    }

    # initialize entities: place entities randomly in the world
    state.entities = 200.map do
      {
        x: (rand * state.world_size - 100).to_i * (rand > 0.5 ? 1 : -1),
        y: (rand * state.world_size - 100).to_i * (rand > 0.5 ? 1 : -1),
        w: 32,
        h: 32,
        angle: 0,
        path: "sprites/square/blue.png",
        rotation_speed: rand * 5
      }
    end

    # backdrop for the world
    state.backdrop = { x: -state.world_size,
                       y: -state.world_size,
                       w: state.world_size * 2,
                       h: state.world_size * 2,
                       r: 200,
                       g: 100,
                       b: 0,
                       a: 128,
                       path: :pixel }

    # rect representing the screen
    state.screen_rect = { x: 0, y: 0, w: 1280, h: 720 }

    # update the camera matricies (initial state)
    update_matricies!
  end

  # if the camera is ever changed, recompute the matricies that are used
  # to translate between screen and world coordinates. we want to cache
  # the resolved matrix for speed
  def update_matricies!
    # camera space is defined with three matricies
    # every entity is:
    # - offset by the location of the camera
    # - scaled
    # - then centered on the screen
    state.to_camera_space_matrix = MatrixFunctions.mul(mat3_translate(state.camera.x, state.camera.y),
                                                       mat3_scale(state.camera.zoom),
                                                       mat3_translate(640, 360))

    # world space is defined based off the camera matricies but inverted:
    # every entity is:
    # - uncentered from the screen
    # - unscaled
    # - offset by the location of the camera in the opposite direction
    state.to_world_space_matrix = MatrixFunctions.mul(mat3_translate(-640, -360),
                                                      mat3_scale(1.0 / state.camera.zoom),
                                                      mat3_translate(-state.camera.x, -state.camera.y))

    # the viewport is computed by taking the screen rect and moving it into world space.
    # what entities get rendered is based off of the viewport
    state.viewport = rect_mul_matrix(state.screen_rect, state.to_world_space_matrix)
  end

  def input
    # if the camera is changed, invalidate/recompute the translation matricies
    should_update_matricies = false

    # + and - keys zoom in and out
    if inputs.keyboard.equal_sign || inputs.keyboard.plus || inputs.mouse.wheel && inputs.mouse.wheel.y > 0
      state.camera.zoom += 0.01 * state.camera.zoom
      should_update_matricies = true
    elsif inputs.keyboard.minus || inputs.mouse.wheel && inputs.mouse.wheel.y < 0
      state.camera.zoom -= 0.01 * state.camera.zoom
      should_update_matricies = true
    end

    # clamp the zoom to a minimum of 0.25
    if state.camera.zoom < 0.25
      state.camera.zoom = 0.25
      should_update_matricies = true
    end

    # left and right keys move the camera left and right
    if inputs.left_right != 0
      state.camera.x += -1 * (inputs.left_right * 10) * state.camera.zoom
      should_update_matricies = true
    end

    # up and down keys move the camera up and down
    if inputs.up_down != 0
      state.camera.y += -1 * (inputs.up_down * 10) * state.camera.zoom
      should_update_matricies = true
    end

    # reset the camera to the default position
    if inputs.keyboard.key_down.zero
      state.camera.x = 0
      state.camera.y = 0
      state.camera.zoom = 1
      should_update_matricies = true
    end

    # if the update matricies flag is set, recompute the matricies
    update_matricies! if should_update_matricies
  end

  def calc
    # rotate all the entities by their rotation speed
    # and reset their hovered state
    state.entities.each do |entity|
      entity.hovered = false
      entity.angle += entity.rotation_speed
    end

    # find all the entities that are hovered by the mouse and update their state back to hovered
    mouse_in_world = rect_to_world_coordinates inputs.mouse.rect
    hovered_entities = geometry.find_all_intersect_rect mouse_in_world, state.entities
    hovered_entities.each { |entity| entity.hovered = true }
  end

  def render
    # create a render target to represent the camera's viewport
    outputs[:scene].transient!
    outputs[:scene].w = state.world_size
    outputs[:scene].h = state.world_size

    # render the backdrop
    outputs[:scene].primitives << rect_to_screen_coordinates(state.backdrop)

    # get all entities that are within the camera's viewport
    entities_to_render = geometry.find_all_intersect_rect state.viewport, state.entities

    # render all the entities within the viewport
    outputs[:scene].primitives << entities_to_render.map do |entity|
      r = rect_to_screen_coordinates entity

      # change the color of the entity if it's hovered
      r.merge!(path: "sprites/square/red.png") if entity.hovered

      r
    end

    # render the camera's viewport
    outputs.sprites << {
      x: 0,
      y: 0,
      w: state.world_size,
      h: state.world_size,
      path: :scene
    }

    # show a label that shows the mouse's screen and world coordinates
    outputs.labels << { x: 30, y: 30.from_top, text: "#{gtk.current_framerate.to_sf}" }

    mouse_in_world = rect_to_world_coordinates inputs.mouse.rect

    outputs.labels << {
      x: 30,
      y: 55.from_top,
      text: "Screen Coordinates: #{inputs.mouse.x}, #{inputs.mouse.y}",
    }

    outputs.labels << {
      x: 30,
      y: 80.from_top,
      text: "World Coordinates: #{mouse_in_world.x.to_sf}, #{mouse_in_world.y.to_sf}",
    }
  end

  def rect_to_screen_coordinates rect
    rect_mul_matrix rect, state.to_camera_space_matrix
  end

  def rect_to_world_coordinates rect
    rect_mul_matrix rect, state.to_world_space_matrix
  end

  def rect_mul_matrix rect, matrix
    # the bottom left and top right corners of the rect
    # are multiplied by the matrix to get the new coordinates
    bottom_left = MatrixFunctions.mul (MatrixFunctions.vec3 rect.x, rect.y, 1), matrix
    top_right   = MatrixFunctions.mul (MatrixFunctions.vec3 rect.x + rect.w, rect.y + rect.h, 1), matrix

    # with the points of the rect recomputed, reconstruct the rect
    rect.merge x: bottom_left.x,
               y: bottom_left.y,
               w: top_right.x - bottom_left.x,
               h: top_right.y - bottom_left.y
  end

  # this is the definition of how to move a point in 2d space using a matrix
  def mat3_translate x, y
    MatrixFunctions.mat3 1, 0, x,
                         0, 1, y,
                         0, 0, 1
  end

  # this is the definition of how to scale a point in 2d space using a matrix
  def mat3_scale scale
    MatrixFunctions.mat3 scale, 0, 0,
                         0, scale, 0,
                         0,     0, 1
  end
end

$game = Game.new

def tick args
  $game.args = args
  $game.tick
end

$gtk.reset

    Matrix Cubeworld - main.rb link

    # ./samples/07_advanced_rendering/16_matrix_cubeworld/app/main.rb
require 'app/modeling-api.rb'

include MatrixFunctions

def tick args
  args.outputs.labels << { x: 0,
                           y: 30.from_top,
                           text: "W,A,S,D to move. Mouse to look. Triangles is a Indie/Pro Feature and will be ignored in Standard.",
                           alignment_enum: 1 }

  args.grid.origin_center!

  args.state.cam_y ||= 0.00
  if args.inputs.keyboard.i
    args.state.cam_y += 0.01
  elsif args.inputs.keyboard.k
    args.state.cam_y -= 0.01
  end

  args.state.cam_angle_y ||= 0
  if args.inputs.keyboard.q
    args.state.cam_angle_y += 0.25
  elsif args.inputs.keyboard.e
    args.state.cam_angle_y -= 0.25
  end

  args.state.cam_angle_x ||= 0
  if args.inputs.keyboard.u
    args.state.cam_angle_x += 0.1
  elsif args.inputs.keyboard.o
    args.state.cam_angle_x -= 0.1
  end

  if args.inputs.mouse.has_focus
    y_change_rate = (args.inputs.mouse.x / 640) ** 2
    if args.inputs.mouse.x < 0
      args.state.cam_angle_y -= 0.8 * y_change_rate
    else
      args.state.cam_angle_y += 0.8 * y_change_rate
    end

    x_change_rate = (args.inputs.mouse.y / 360) ** 2
    if args.inputs.mouse.y < 0
      args.state.cam_angle_x += 0.8 * x_change_rate
    else
      args.state.cam_angle_x -= 0.8 * x_change_rate
    end
  end

  args.state.cam_z ||= 6.4
  if args.inputs.keyboard.up
    point_1 = { x: 0, y: 0.02 }
    point_r = args.geometry.rotate_point point_1, args.state.cam_angle_y
    args.state.cam_x -= point_r.x
    args.state.cam_z -= point_r.y
  elsif args.inputs.keyboard.down
    point_1 = { x: 0, y: -0.02 }
    point_r = args.geometry.rotate_point point_1, args.state.cam_angle_y
    args.state.cam_x -= point_r.x
    args.state.cam_z -= point_r.y
  end

  args.state.cam_x ||= 0.00
  if args.inputs.keyboard.right
    point_1 = { x: -0.02, y: 0 }
    point_r = args.geometry.rotate_point point_1, args.state.cam_angle_y
    args.state.cam_x -= point_r.x
    args.state.cam_z -= point_r.y
  elsif args.inputs.keyboard.left
    point_1 = { x:  0.02, y: 0 }
    point_r = args.geometry.rotate_point point_1, args.state.cam_angle_y
    args.state.cam_x -= point_r.x
    args.state.cam_z -= point_r.y
  end


  if args.inputs.keyboard.key_down.r || args.inputs.keyboard.key_down.zero
    args.state.cam_x = 0.00
    args.state.cam_y = 0.00
    args.state.cam_z = 1.00
    args.state.cam_angle_y = 0
    args.state.cam_angle_x = 0
  end

  if !args.state.models
    args.state.models = []
    25.times do
      args.state.models.concat new_random_cube
    end
  end

  args.state.models.each do |m|
    render_triangles args, m
  end

  args.outputs.lines << { x:   0, y: -50, h: 100, a: 80 }
  args.outputs.lines << { x: -50, y:   0, w: 100, a: 80 }
end

def mul_triangles model, *mul_def
  combined = mul mul_def
  model.map do |vecs|
    vecs.map do |vec|
      mul vec, *combined
    end
  end
end

def mul_cam args, world_vecs
  mul_triangles world_vecs,
                (translate -args.state.cam_x, -args.state.cam_y, -args.state.cam_z),
                (rotate_y args.state.cam_angle_y),
                (rotate_x args.state.cam_angle_x)
end

def mul_perspective camera_vecs
  camera_vecs.map do |vecs|
    r = vecs.map do |vec|
      perspective vec
    end

    r if r[0] && r[1] && r[2]
  end.reject_nil
end

def render_debug args, model, transform, projected
  args.outputs.labels << { x: -630, y:  10.from_top,  text: "model:     #{vecs_to_s model[0]}" }
  args.outputs.labels << { x: -630, y:  30.from_top,  text: "           #{vecs_to_s model[1]}" }
  args.outputs.labels << { x: -630, y:  50.from_top,  text: "transform: #{vecs_to_s transform[0]}" }
  args.outputs.labels << { x: -630, y:  70.from_top,  text: "           #{vecs_to_s transform[1]}" }
  args.outputs.labels << { x: -630, y:  90.from_top,  text: "projected: #{vecs_to_s projected[0]}" }
  args.outputs.labels << { x: -630, y: 110.from_top,  text: "           #{vecs_to_s projected[1]}" }
end

def render_triangles args, triangles
  camera_space = mul_cam args, triangles
  projection = mul_perspective camera_space

  args.outputs.sprites << projection.map_with_index do |i, index|
    if i
      {
        x:  i[0].x,   y: i[0].y,
        x2: i[1].x,  y2: i[1].y,
        x3: i[2].x,  y3: i[2].y,
        source_x:   0, source_y:   0,
        source_x2: 80, source_y2:  0,
        source_x3:  0, source_y3: 80,
        r: 128, g: 128, b: 128,
        a: 80 + 128 * 1 / (index + 1),
        path: :pixel
      }
    end
  end
end

def perspective vec
  left   =  100.0
  right  = -100.0
  bottom =  100.0
  top    = -100.0
  near   =  3000.0
  far    =  8000.0
  sx = 2 * near / (right - left)
  sy = 2 * near / (top - bottom)
  c2 = - (far + near) / (far - near)
  c1 = 2 * near * far / (near - far)
  tx = -near * (left + right) / (right - left)
  ty = -near * (bottom + top) / (top - bottom)

  p = mat4 sx, 0, 0, tx,
           0, sy, 0, ty,
           0, 0, c2, c1,
           0, 0, -1, 0

  r = mul vec, p
  return nil if r.w < 0
  r.x *= r.z / r.w / 100
  r.y *= r.z / r.w / 100
  r
end

def mat_scale scale
  mat4 scale,     0,     0,   0,
           0, scale,     0,   0,
           0,     0, scale,   0,
           0,     0,     0,   1
end

def rotate_y angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  (mat4  cos_t,  0, sin_t, 0,
         0,      1, 0,     0,
         -sin_t, 0, cos_t, 0,
         0,      0, 0,     1)
end

def rotate_z angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  (mat4 cos_t, -sin_t, 0, 0,
        sin_t,  cos_t, 0, 0,
        0,      0,     1, 0,
        0,      0,     0, 1)
end

def translate dx, dy, dz
  mat4 1, 0, 0, dx,
       0, 1, 0, dy,
       0, 0, 1, dz,
       0, 0, 0,  1
end


def rotate_x angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  (mat4  1,     0,      0, 0,
         0, cos_t, -sin_t, 0,
         0, sin_t,  cos_t, 0,
         0,     0,      0, 1)
end

def vecs_to_s vecs
  vecs.map do |vec|
    "[#{vec.x.to_sf} #{vec.y.to_sf} #{vec.z.to_sf}]"
  end.join " "
end

def new_random_cube
  cube_w = rand * 0.2 + 0.1
  cube_h = rand * 0.2 + 0.1
  randx = rand * 2.0 * [1, -1].sample
  randy = rand * 2.0
  randz = rand * 5   * [1, -1].sample

  cube = [
    square do
      scale x: cube_w, y: cube_h
      translate x: -cube_w / 2, y: -cube_h / 2
      rotate_x 90
      translate y: -cube_h / 2
      translate x: randx, y: randy, z: randz
    end,
    square do
      scale x: cube_w, y: cube_h
      translate x: -cube_w / 2, y: -cube_h / 2
      rotate_x 90
      translate y:  cube_h / 2
      translate x: randx, y: randy, z: randz
    end,
    square do
      scale x: cube_h, y: cube_h
      translate x: -cube_h / 2, y: -cube_h / 2
      rotate_y 90
      translate x: -cube_w / 2
      translate x: randx, y: randy, z: randz
    end,
    square do
      scale x: cube_h, y: cube_h
      translate x: -cube_h / 2, y: -cube_h / 2
      rotate_y 90
      translate x:  cube_w / 2
      translate x: randx, y: randy, z: randz
    end,
    square do
      scale x: cube_w, y: cube_h
      translate x: -cube_w / 2, y: -cube_h / 2
      translate z: -cube_h / 2
      translate x: randx, y: randy, z: randz
    end,
    square do
      scale x: cube_w, y: cube_h
      translate x: -cube_w / 2, y: -cube_h / 2
      translate z:  cube_h / 2
      translate x: randx, y: randy, z: randz
    end
  ]

  cube
end

$gtk.reset

    Matrix Cubeworld - modeling-api.rb link

    # ./samples/07_advanced_rendering/16_matrix_cubeworld/app/modeling-api.rb
class ModelingApi
  attr :matricies

  def initialize
    @matricies = []
  end

  def scale x: 1, y: 1, z: 1
    @matricies << scale_matrix(x: x, y: y, z: z)
    if block_given?
      yield
      @matricies << scale_matrix(x: -x, y: -y, z: -z)
    end
  end

  def translate x: 0, y: 0, z: 0
    @matricies << translate_matrix(x: x, y: y, z: z)
    if block_given?
      yield
      @matricies << translate_matrix(x: -x, y: -y, z: -z)
    end
  end

  def rotate_x x
    @matricies << rotate_x_matrix(x)
    if block_given?
      yield
      @matricies << rotate_x_matrix(-x)
    end
  end

  def rotate_y y
    @matricies << rotate_y_matrix(y)
    if block_given?
      yield
      @matricies << rotate_y_matrix(-y)
    end
  end

  def rotate_z z
    @matricies << rotate_z_matrix(z)
    if block_given?
      yield
      @matricies << rotate_z_matrix(-z)
    end
  end

  def scale_matrix x:, y:, z:;
    mat4 x, 0, 0, 0,
         0, y, 0, 0,
         0, 0, z, 0,
         0, 0, 0, 1
  end

  def translate_matrix x:, y:, z:;
    mat4 1, 0, 0, x,
         0, 1, 0, y,
         0, 0, 1, z,
         0, 0, 0, 1
  end

  def rotate_y_matrix angle_d
    cos_t = Math.cos angle_d.to_radians
    sin_t = Math.sin angle_d.to_radians
    (mat4  cos_t,  0, sin_t, 0,
           0,      1, 0,     0,
           -sin_t, 0, cos_t, 0,
           0,      0, 0,     1)
  end

  def rotate_z_matrix angle_d
    cos_t = Math.cos angle_d.to_radians
    sin_t = Math.sin angle_d.to_radians
    (mat4 cos_t, -sin_t, 0, 0,
          sin_t,  cos_t, 0, 0,
          0,      0,     1, 0,
          0,      0,     0, 1)
  end

  def rotate_x_matrix angle_d
    cos_t = Math.cos angle_d.to_radians
    sin_t = Math.sin angle_d.to_radians
    (mat4  1,     0,      0, 0,
           0, cos_t, -sin_t, 0,
           0, sin_t,  cos_t, 0,
           0,     0,      0, 1)
  end

  def __mul_triangles__ model, *mul_def
    model.map do |vecs|
      vecs.map do |vec|
        mul vec,
            *mul_def
      end
    end
  end
end

def square &block
  square_verticies = [
    [vec4(0, 0, 0, 1),   vec4(1.0, 0, 0, 1),   vec4(0, 1.0, 0, 1)],
    [vec4(1.0, 0, 0, 1), vec4(1.0, 1.0, 0, 1), vec4(0, 1.0, 0, 1)]
  ]

  m = ModelingApi.new
  m.instance_eval &block if block
  m.__mul_triangles__ square_verticies, *m.matricies
end

    Override Core Rendering - main.rb link

    # ./samples/07_advanced_rendering/17_override_core_rendering/app/main.rb
class GTK::Runtime
  # You can completely override how DR renders by defining this method
  # It is strongly recommend that you do not do this unless you know what you're doing.
  def primitives pass
    # fn.each_send pass.solids,            self, :draw_solid
    # fn.each_send pass.static_solids,     self, :draw_solid
    # fn.each_send pass.sprites,           self, :draw_sprite
    # fn.each_send pass.static_sprites,    self, :draw_sprite
    # fn.each_send pass.primitives,        self, :draw_primitive
    # fn.each_send pass.static_primitives, self, :draw_primitive
    fn.each_send pass.labels,            self, :draw_label
    fn.each_send pass.static_labels,     self, :draw_label
    # fn.each_send pass.lines,             self, :draw_line
    # fn.each_send pass.static_lines,      self, :draw_line
    # fn.each_send pass.borders,           self, :draw_border
    # fn.each_send pass.static_borders,    self, :draw_border

    # if !self.production
    #   fn.each_send pass.debug,           self, :draw_primitive
    #   fn.each_send pass.static_debug,    self, :draw_primitive
    # end

    # fn.each_send pass.reserved,          self, :draw_primitive
    # fn.each_send pass.static_reserved,   self, :draw_primitive
  end
end

def tick args
  args.outputs.labels << { x: 30, y: 30, text: "primitives function defined, only labels rendered" }
  args.outputs.sprites << { x: 100, y: 100, w: 100, h: 100, path: "dragonruby.png" }
end

    Layouts - main.rb link

    # ./samples/07_advanced_rendering/18_layouts/app/main.rb
def tick args
  args.outputs.solids << args.layout.rect(row: 0,
                                          col: 0,
                                          w: 24,
                                          h: 12,
                                          include_row_gutter: true,
                                          include_col_gutter: true).merge(b: 255, a: 80)
  render_row_examples args
  render_column_examples args
  render_max_width_max_height_examples args
  render_points_with_anchored_label_examples args
  render_centered_rect_examples args
  render_rect_group_examples args
end

def render_row_examples args
  # rows (light blue)
  args.outputs.labels << args.layout.rect(row: 1, col: 6 + 3).merge(text: "row examples", anchor_x: 0.5, anchor_y: 0.5)
  4.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row, col: 6, w: 1, h: 1).merge(**light_blue)
  end

  2.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row * 2, col: 6 + 1, w: 1, h: 2).merge(**light_blue)
  end

  4.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row, col: 6 + 2, w: 2, h: 1).merge(**light_blue)
  end

  2.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row * 2, col: 6 + 4, w: 2, h: 2).merge(**light_blue)
  end
end

def render_column_examples args
  # columns (yellow)
  yellow = { r: 255, g: 255, b: 128 }
  args.outputs.labels << args.layout.rect(row: 1, col: 12 + 3).merge(text: "column examples", anchor_x: 0.5, anchor_y: 0.5)
  6.times do |col|
    args.outputs.solids << args.layout.rect(row: 0, col: 12 + col, w: 1, h: 1).merge(**yellow)
  end

  3.times do |col|
    args.outputs.solids << args.layout.rect(row: 1, col: 12 + col * 2, w: 2, h: 1).merge(**yellow)
  end

  6.times do |col|
    args.outputs.solids << args.layout.rect(row: 2, col: 12 + col, w: 1, h: 2).merge(**yellow)
  end
end

def render_max_width_max_height_examples args
  # max width/height baseline (transparent green)
  args.outputs.labels << args.layout.rect(row: 4, col: 12).merge(text: "max width/height examples", anchor_x: 0.5, anchor_y: 0.5)
  args.outputs.solids << args.layout.rect(row: 4, col: 0, w: 24, h: 2).merge(a: 64, **green)

  # max height
  args.outputs.solids << args.layout.rect(row: 4, col: 0, w: 24, h: 2, max_height: 1).merge(a: 64, **green)

  # max width
  args.outputs.solids << args.layout.rect(row: 4, col: 0, w: 24, h: 2, max_width: 12).merge(a: 64, **green)
end

def render_points_with_anchored_label_examples args
  # labels relative to rects
  label_color = { r: 0, g: 0, b: 0 }

  # labels realtive to point, achored at 0.0, 0.0
  args.outputs.borders << args.layout.rect(row: 6, col: 3, w: 6, h: 5)
  args.outputs.labels << args.layout.rect(row: 6, col: 3, w: 6, h: 1).center.merge(text: "layout.point anchored to 0.0, 0.0", anchor_x: 0.5, anchor_y: 0.5, size_px: 15)
  grey = { r: 128, g: 128, b: 128 }
  args.outputs.solids << args.layout.rect(row: 7, col: 4.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 7, col: 4.5, row_anchor: 1.0, col_anchor: 0.0).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 7, col: 5.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 7, col: 5.5, row_anchor: 1.0, col_anchor: 0.5).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 7, col: 6.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 7, col: 6.5, row_anchor: 1.0, col_anchor: 1.0).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 8, col: 4.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 8, col: 4.5, row_anchor: 0.5, col_anchor: 0.0).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 8, col: 5.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 8, col: 5.5, row_anchor: 0.5, col_anchor: 0.5).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 8, col: 6.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 8, col: 6.5, row_anchor: 0.5, col_anchor: 1.0).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 9, col: 4.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 9, col: 4.5, row_anchor: 0.0, col_anchor: 0.0).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 9, col: 5.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 9, col: 5.5, row_anchor: 0.0, col_anchor: 0.5).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)

  args.outputs.solids << args.layout.rect(row: 9, col: 6.5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 9, col: 6.5, row_anchor: 0.0, col_anchor: 1.0).merge(text: "[x]", anchor_x: 0.5, anchor_y: 0.5, **label_color)
end

def render_centered_rect_examples args
  # centering rects
  args.outputs.borders << args.layout.rect(row: 6, col: 9, w: 6, h: 5)
  args.outputs.labels << args.layout.rect(row: 6, col: 9, w: 6, h: 1).center.merge(text: "layout.rect centered inside another rect", anchor_x: 0.5, anchor_y: 0.5, size_px: 15)
  outer_rect = args.layout.rect(row: 7, col: 10.5, w: 3, h: 3)

  # render outer rect
  args.outputs.solids << outer_rect.merge(**light_blue)

  # # center a yellow rect with w and h of two
  args.outputs.solids << args.layout.rect_center(
    args.layout.rect(w: 1, h: 5), # inner rect
    outer_rect, # outer rect
  ).merge(**yellow)

  # # center a black rect with w three h of one
  args.outputs.solids << args.layout.rect_center(
    args.layout.rect(w: 5, h: 1), # inner rect
    outer_rect, # outer rect
  )
end

def render_rect_group_examples args
  args.outputs.labels << args.layout.rect(row: 6, col: 15, w: 6, h: 1).center.merge(text: "layout.rect_group usage", anchor_x: 0.5, anchor_y: 0.5, size_px: 15)
  args.outputs.borders << args.layout.rect(row: 6, col: 15, w: 6, h: 5)

  horizontal_markers = [
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
  ]

  args.outputs.solids << args.layout.rect_group(row: 7,
                                                col: 15,
                                                dcol: 1,
                                                w: 1,
                                                h: 1,
                                                group: horizontal_markers)

  vertical_markers = [
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 }
  ]

  args.outputs.solids << args.layout.rect_group(row: 7,
                                                col: 15,
                                                drow: 1,
                                                w: 1,
                                                h: 1,
                                                group: vertical_markers)

  colors = [
    { r:   0, g:   0, b:   0 },
    { r:  50, g:  50, b:  50 },
    { r: 100, g: 100, b: 100 },
    { r: 150, g: 150, b: 150 },
    { r: 200, g: 200, b: 200 },
    { r: 250, g: 250, b: 250 },
  ]

  args.outputs.solids << args.layout.rect_group(row: 8,
                                                col: 15,
                                                dcol: 1,
                                                w: 1,
                                                h: 1,
                                                group: colors)
end

def light_blue
  { r: 128, g: 255, b: 255 }
end

def yellow
  { r: 255, g: 255, b: 128 }
end

def green
  { r: 0, g: 128, b: 80 }
end

def white
  { r: 255, g: 255, b: 255 }
end

def label_color
  { r: 0, g: 0, b: 0 }
end

$gtk.reset

    Advanced Rendering Hd link

    Hd Labels - main.rb link

    # ./samples/07_advanced_rendering_hd/01_hd_labels/app/main.rb
def tick args
  args.state.output_cycle ||= :top_level

  args.outputs.background_color = [0, 0, 0]
  args.outputs.solids << [0, 0, 1280, 720, 255, 255, 255]
  if args.state.output_cycle == :top_level
    render_main args
  else
    render_scene args
  end

  # cycle between labels in top level args.outputs
  # and labels inside of render target
  if args.state.tick_count.zmod? 300
    if args.state.output_cycle == :top_level
      args.state.output_cycle = :render_target
    else
      args.state.output_cycle = :top_level
    end
  end
end

def render_main args
  # center line
  args.outputs.lines   << { x:   0, y: 360, x2: 1280, y2: 360 }
  args.outputs.lines   << { x: 640, y:   0, x2:  640, y2: 720 }

  # horizontal ruler
  args.outputs.lines   << { x:   0, y: 370, x2: 1280, y2: 370 }
  args.outputs.lines   << { x:   0, y: 351, x2: 1280, y2: 351 }

  # vertical ruler
  args.outputs.lines   << { x:  575, y: 0, x2: 575, y2: 720 }
  args.outputs.lines   << { x:  701, y: 0, x2: 701, y2: 720 }

  args.outputs.sprites << { x: 640 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square/blue.png", a: 128 }
  args.outputs.labels  << { x:  640, y:   0, text: "(bottom)",  alignment_enum: 1, vertical_alignment_enum: 0 }
  args.outputs.labels  << { x:  640, y: 425, text: "top_level", alignment_enum: 1, vertical_alignment_enum: 1 }
  args.outputs.labels  << { x:  640, y: 720, text: "(top)",     alignment_enum: 1, vertical_alignment_enum: 2 }
  args.outputs.labels  << { x:    0, y: 360, text: "(left)",    alignment_enum: 0, vertical_alignment_enum: 1 }
  args.outputs.labels  << { x: 1280, y: 360, text: "(right)",   alignment_enum: 2, vertical_alignment_enum: 1 }
end

def render_scene args
  args.outputs[:scene].transient!
  args.outputs[:scene].background_color = [255, 255, 255, 0]

  # center line
  args.outputs[:scene].lines   << { x:   0, y: 360, x2: 1280, y2: 360 }
  args.outputs[:scene].lines   << { x: 640, y:   0, x2:  640, y2: 720 }

  # horizontal ruler
  args.outputs[:scene].lines   << { x:   0, y: 370, x2: 1280, y2: 370 }
  args.outputs[:scene].lines   << { x:   0, y: 351, x2: 1280, y2: 351 }

  # vertical ruler
  args.outputs[:scene].lines   << { x:  575, y: 0, x2: 575, y2: 720 }
  args.outputs[:scene].lines   << { x:  701, y: 0, x2: 701, y2: 720 }

  args.outputs[:scene].sprites << { x: 640 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square/blue.png", a: 128, blendmode_enum: 0 }
  args.outputs[:scene].labels  << { x:  640, y:   0, text: "(bottom)",      alignment_enum: 1, vertical_alignment_enum: 0, blendmode_enum: 0 }
  args.outputs[:scene].labels  << { x:  640, y: 425, text: "render target", alignment_enum: 1, vertical_alignment_enum: 1, blendmode_enum: 0 }
  args.outputs[:scene].labels  << { x:  640, y: 720, text: "(top)",         alignment_enum: 1, vertical_alignment_enum: 2, blendmode_enum: 0 }
  args.outputs[:scene].labels  << { x:    0, y: 360, text: "(left)",        alignment_enum: 0, vertical_alignment_enum: 1, blendmode_enum: 0 }
  args.outputs[:scene].labels  << { x: 1280, y: 360, text: "(right)",       alignment_enum: 2, vertical_alignment_enum: 1, blendmode_enum: 0 }

  args.outputs.sprites << { x: 0, y: 0, w: 1280, h: 720, path: :scene }
end

    Texture Atlases - main.rb link

    # ./samples/07_advanced_rendering_hd/02_texture_atlases/app/main.rb
# With HD mode enabled. DragonRuby will automatically use HD sprites given the following
# naming convention (assume we are using a sprite called =player.png=):
#
# | Name  | Resolution | File Naming Convention        |
# |-------+------------+-------------------------------|
# | 720p  |   1280x720 | =player.png=                  |
# | HD+   |   1600x900 | [email protected]=              |
# | 1080p |  1920x1080 | [email protected]=              |
# | 1440p |  2560x1440 | [email protected]=              |
# | 1800p |  3200x1800 | [email protected]=              |
# | 4k    |  3200x2160 | [email protected]=              |
# | 5k    |  6400x2880 | [email protected]=              |

# Note: Review the sample app's game_metadata.txt file for what configurations are enabled.

def tick args
  args.outputs.background_color = [0, 0, 0]
  args.outputs.borders << { x: 0, y: 0, w: 1280, h: 720, r: 255, g: 255, b: 255 }

  args.outputs.labels << { x: 30, y: 30.from_top, text: "render scale: #{args.grid.native_scale}", r: 255, g: 255, b: 255 }
  args.outputs.labels << { x: 30, y: 60.from_top, text: "render scale: #{args.grid.native_scale_enum}", r: 255, g: 255, b: 255 }

  args.outputs.sprites << { x: -640 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x: -320 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }

  args.outputs.sprites << { x:    0 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x:  320 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x:  640 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x:  960 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x: 1280 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }

  args.outputs.sprites << { x: 1600 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x: 1920 - 50, y: 360 - 50, w: 100, h: 100, path: "sprites/square.png" }

  args.outputs.sprites << { x:  640 - 50, y:          720, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x:  640 - 50, y: 100.from_top, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x:  640 - 50, y:     360 - 50, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x:  640 - 50, y:            0, w: 100, h: 100, path: "sprites/square.png" }
  args.outputs.sprites << { x:  640 - 50, y:         -100, w: 100, h: 100, path: "sprites/square.png" }
end

    Allscreen Properties - main.rb link

    # ./samples/07_advanced_rendering_hd/03_allscreen_properties/app/main.rb
def tick args
  label_style = { r: 255, g: 255, b: 255, size_enum: 4 }
  args.outputs.background_color = [0, 0, 0]
  args.outputs.borders << { x: 0, y: 0, w: 1280, h: 720, r: 255, g: 255, b: 255 }

  args.outputs.labels << { x: 10, y:  10.from_top, text: "native_scale:       #{args.grid.native_scale}", **label_style }
  args.outputs.labels << { x: 10, y:  40.from_top, text: "native_scale_enum:  #{args.grid.native_scale_enum}",  **label_style }
  args.outputs.labels << { x: 10, y:  70.from_top, text: "hd_offset_x:        #{args.grid.hd_offset_x}", **label_style }
  args.outputs.labels << { x: 10, y: 100.from_top, text: "hd_offset_y:        #{args.grid.hd_offset_y}", **label_style }

  if (args.state.tick_count % 500) < 250
    args.outputs.labels << { x: 10, y: 130.from_top, text: "cropped to:         grid", **label_style }

    args.outputs.sprites << { x:        0,
                              y:        0,
                              w:        1280,
                              h:        720,
                              source_x: 2000 - 640,
                              source_y: 2000 - 320,
                              source_w: 1280,
                              source_h: 720,
                              path: "sprites/world.png" }
  else
    args.outputs.labels << { x: 10, y: 130.from_top, text: "cropped to:         allscreen", **label_style }

    args.outputs.sprites << { x:        0    - args.grid.hd_offset_x,
                              y:        0    - args.grid.hd_offset_y,
                              w:        1280 + args.grid.hd_offset_x * 2,
                              h:        720  + args.grid.hd_offset_y * 2,
                              source_x: 2000 - 640 - args.grid.hd_offset_x,
                              source_y: 2000 - 320 - args.grid.hd_offset_y,
                              source_w: 1280 + args.grid.hd_offset_x * 2,
                              source_h: 720  + args.grid.hd_offset_y * 2,
                              path:     "sprites/world.png" }

    args.outputs.sprites << { x:        0    - args.grid.hd_offset_x,
                              y:        0    - args.grid.hd_offset_y,
                              w:        1280 + args.grid.hd_offset_x * 2,
                              h:        720  + args.grid.hd_offset_y * 2,
                              source_x: 2000 - 640 - args.grid.hd_offset_x,
                              source_y: 2000 - 320 - args.grid.hd_offset_y,
                              source_w: 1280 + args.grid.hd_offset_x * 2,
                              source_h: 720  + args.grid.hd_offset_y * 2,
                              path:     "sprites/world.png" }
  end

  args.outputs.sprites << { x: 0, y: 0.from_top - 165, w: 410, h: 165, r: 0, g: 0, b: 0, a: 200, path: :pixel }
end

    Layouts And Portrait Mode - main.rb link

    # ./samples/07_advanced_rendering_hd/04_layouts_and_portrait_mode/app/main.rb
def tick args
  args.outputs.solids << args.layout.rect(row: 0, col: 0, w: 12, h: 24, include_row_gutter: true, include_col_gutter: true).merge(b: 255, a: 80)

  # rows (light blue)
  light_blue = { r: 128, g: 255, b: 255 }
  args.outputs.labels << args.layout.rect(row: 1, col: 3).merge(text: "row examples", vertical_alignment_enum: 1, alignment_enum: 1)
  4.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row, col: 0, w: 1, h: 1).merge(**light_blue)
  end

  2.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row * 2, col: 1, w: 1, h: 2).merge(**light_blue)
  end

  4.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row, col: 2, w: 2, h: 1).merge(**light_blue)
  end

  2.map_with_index do |row|
    args.outputs.solids << args.layout.rect(row: row * 2, col: 4, w: 2, h: 2).merge(**light_blue)
  end

  # columns (yellow)
  yellow = { r: 255, g: 255, b: 128 }
  args.outputs.labels << args.layout.rect(row: 1, col: 9).merge(text: "column examples", vertical_alignment_enum: 1, alignment_enum: 1)
  6.times do |col|
    args.outputs.solids << args.layout.rect(row: 0, col: 6 + col, w: 1, h: 1).merge(**yellow)
  end

  3.times do |col|
    args.outputs.solids << args.layout.rect(row: 1, col: 6 + col * 2, w: 2, h: 1).merge(**yellow)
  end

  6.times do |col|
    args.outputs.solids << args.layout.rect(row: 2, col: 6 + col, w: 1, h: 2).merge(**yellow)
  end

  # max width/height baseline (transparent green)
  green = { r: 0, g: 128, b: 80 }
  args.outputs.labels << args.layout.rect(row: 4, col: 6).merge(text: "max width/height examples", vertical_alignment_enum: 1, alignment_enum: 1)
  args.outputs.solids << args.layout.rect(row: 4, col: 0, w: 12, h: 2).merge(a: 64, **green)

  # max height
  args.outputs.solids << args.layout.rect(row: 4, col: 0, w: 12, h: 2, max_height: 1).merge(a: 64, **green)

  # max width
  args.outputs.solids << args.layout.rect(row: 4, col: 0, w: 12, h: 2, max_width: 6).merge(a: 64, **green)

  # labels relative to rects
  label_color = { r: 0, g: 0, b: 0 }
  white = { r: 232, g: 232, b: 232 }

  # labels realtive to point, achored at 0.0, 0.0
  args.outputs.labels << args.layout.rect(row: 5.5, col: 6).merge(text: "labels using args.layout.point anchored to 0.0, 0.0", vertical_alignment_enum: 1, alignment_enum: 1)
  grey = { r: 128, g: 128, b: 128 }
  args.outputs.solids << args.layout.rect(row: 7, col: 4).merge(**grey)
  args.outputs.labels << args.layout.point(row: 7, col: 4, row_anchor: 1.0, col_anchor: 0.0).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 7, col: 5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 7, col: 5, row_anchor: 1.0, col_anchor: 0.5).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 7, col: 6).merge(**grey)
  args.outputs.labels << args.layout.point(row: 7, col: 6, row_anchor: 1.0, col_anchor: 1.0).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 8, col: 4).merge(**grey)
  args.outputs.labels << args.layout.point(row: 8, col: 4, row_anchor: 0.5, col_anchor: 0.0).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 8, col: 5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 8, col: 5, row_anchor: 0.5, col_anchor: 0.5).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 8, col: 6).merge(**grey)
  args.outputs.labels << args.layout.point(row: 8, col: 6, row_anchor: 0.5, col_anchor: 1.0).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 9, col: 4).merge(**grey)
  args.outputs.labels << args.layout.point(row: 9, col: 4, row_anchor: 0.0, col_anchor: 0.0).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 9, col: 5).merge(**grey)
  args.outputs.labels << args.layout.point(row: 9, col: 5, row_anchor: 0.0, col_anchor: 0.5).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  args.outputs.solids << args.layout.rect(row: 9, col: 6).merge(**grey)
  args.outputs.labels << args.layout.point(row: 9, col: 6, row_anchor: 0.0, col_anchor: 1.0).merge(text: "[x]", alignment_enum: 1, vertical_alignment_enum: 1, **label_color)

  # centering rects
  args.outputs.labels << args.layout.rect(row: 10.5, col: 6).merge(text: "layout.rect centered inside another layout.rect", vertical_alignment_enum: 1, alignment_enum: 1)
  outer_rect = args.layout.rect(row: 12, col: 4, w: 3, h: 3)

  # render outer rect
  args.outputs.solids << outer_rect.merge(**light_blue)

  # center a yellow rect with w and h of two
  args.outputs.solids << args.layout.rect_center(
    args.layout.rect(w: 1, h: 5), # inner rect
    outer_rect, # outer rect
  ).merge(**yellow)

  # center a black rect with w three h of one
  args.outputs.solids << args.layout.rect_center(
    args.layout.rect(w: 5, h: 1), # inner rect
    outer_rect, # outer rect
  )

  args.outputs.labels << args.layout.rect(row: 16.5, col: 6).merge(text: "layout.rect_group usage", vertical_alignment_enum: 1, alignment_enum: 1)

  horizontal_markers = [
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 }
  ]

  args.outputs.solids << args.layout.rect_group(row: 18,
                                                dcol: 1,
                                                w: 1,
                                                h: 1,
                                                group: horizontal_markers)

  vertical_markers = [
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 },
    { r: 0, g: 0, b: 0 }
  ]

  args.outputs.solids << args.layout.rect_group(row: 18,
                                                drow: 1,
                                                w: 1,
                                                h: 1,
                                                group: vertical_markers)

  colors = [
    { r:   0, g:   0, b:   0 },
    { r:  50, g:  50, b:  50 },
    { r: 100, g: 100, b: 100 },
    { r: 150, g: 150, b: 150 },
    { r: 200, g: 200, b: 200 },
  ]

  args.outputs.solids << args.layout.rect_group(row: 19,
                                                col: 1,
                                                dcol: 2,
                                                w: 2,
                                                h: 1,
                                                group: colors)

  args.outputs.solids << args.layout.rect_group(row: 19,
                                                col: 1,
                                                drow: 1,
                                                w: 2,
                                                h: 1,
                                                group: colors)
end

$gtk.reset

    Tweening Lerping Easing Functions link

    Easing Functions - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/01_easing_functions/app/main.rb
def tick args
  # STOP! Watch the following presentation first!!!!
  # Math for Game Programmers: Fast and Funky 1D Nonlinear Transformations
  # https://www.youtube.com/watch?v=mr5xkf6zSzk

  # You've watched the talk, yes? YES???

  # define starting and ending points of properties to animate
  args.state.target_x = 1180
  args.state.target_y = 620
  args.state.target_w = 100
  args.state.target_h = 100
  args.state.starting_x = 0
  args.state.starting_y = 0
  args.state.starting_w = 300
  args.state.starting_h = 300

  # define start time and duration of animation
  args.state.start_animate_at = 3.seconds # this is the same as writing 60 * 5 (or 300)
  args.state.duration = 2.seconds # this is the same as writing 60 * 2 (or 120)

  # define type of animations
  # Here are all the options you have for values you can put in the array:
  # :identity, :quad, :cube, :quart, :quint, :flip

  # Linear is defined as:
  # [:identity]
  #
  # Smooth start variations are:
  # [:quad]
  # [:cube]
  # [:quart]
  # [:quint]

  # Linear reversed, and smooth stop are the same as the animations defined above, but reversed:
  # [:flip, :identity]
  # [:flip, :quad, :flip]
  # [:flip, :cube, :flip]
  # [:flip, :quart, :flip]
  # [:flip, :quint, :flip]

  # You can also do custom definitions. See the bottom of the file details
  # on how to do that. I've defined a couple for you:
  # [:smoothest_start]
  # [:smoothest_stop]

  # CHANGE THIS LINE TO ONE OF THE LINES ABOVE TO SEE VARIATIONS
  args.state.animation_type = [:identity]
  # args.state.animation_type = [:quad]
  # args.state.animation_type = [:cube]
  # args.state.animation_type = [:quart]
  # args.state.animation_type = [:quint]
  # args.state.animation_type = [:flip, :identity]
  # args.state.animation_type = [:flip, :quad, :flip]
  # args.state.animation_type = [:flip, :cube, :flip]
  # args.state.animation_type = [:flip, :quart, :flip]
  # args.state.animation_type = [:flip, :quint, :flip]
  # args.state.animation_type = [:smoothest_start]
  # args.state.animation_type = [:smoothest_stop]

  # THIS IS WHERE THE MAGIC HAPPENS!
  # Numeric#ease
  progress = args.state.start_animate_at.ease(args.state.duration, args.state.animation_type)

  # Numeric#ease needs to called:
  # 1. On the number that represents the point in time you want to start, and takes two parameters:
  #   a. The first parameter is how long the animation should take.
  #   b. The second parameter represents the functions that need to be called.
  #
  # For example, if I wanted an animate to start 3 seconds in, and last for 10 seconds,
  # and I want to animation to start fast and end slow, I would do:
  # (60 * 3).ease(60 * 10, :flip, :quint, :flip)

  #        initial value           delta to the final value
  calc_x = args.state.starting_x + (args.state.target_x - args.state.starting_x) * progress
  calc_y = args.state.starting_y + (args.state.target_y - args.state.starting_y) * progress
  calc_w = args.state.starting_w + (args.state.target_w - args.state.starting_w) * progress
  calc_h = args.state.starting_h + (args.state.target_h - args.state.starting_h) * progress

  args.outputs.solids << [calc_x, calc_y, calc_w, calc_h, 0, 0, 0]

  # count down
  count_down = args.state.start_animate_at - args.state.tick_count
  if count_down > 0
    args.outputs.labels << [640, 375, "Running: #{args.state.animation_type} in...", 3, 1]
    args.outputs.labels << [640, 345, "%.2f" % count_down.fdiv(60), 3, 1]
  elsif progress >= 1
    args.outputs.labels << [640, 360, "Click screen to reset.", 3, 1]
    if args.inputs.click
      $gtk.reset
    end
  end
end

# $gtk.reset

# you can make own variations of animations using this
module Easing
  # you have access to all the built in functions: identity, flip, quad, cube, quart, quint
  def self.smoothest_start x
    quad(quint(x))
  end

  def self.smoothest_stop x
    flip(quad(quint(flip(x))))
  end

  # this is the source for the existing easing functions
  def self.identity x
    x
  end

  def self.flip x
    1 - x
  end

  def self.quad x
    x * x
  end

  def self.cube x
    x * x * x
  end

  def self.quart x
    x * x * x * x * x
  end

  def self.quint x
    x * x * x * x * x * x
  end
end

    Cubic Bezier - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/02_cubic_bezier/app/main.rb
def tick args
  args.outputs.background_color = [33, 33, 33]
  args.outputs.lines << bezier(100, 100,
                               100, 620,
                               1180, 620,
                               1180, 100,
                               0)

  args.outputs.lines << bezier(100, 100,
                               100, 620,
                               1180, 620,
                               1180, 100,
                               20)
end


def bezier x1, y1, x2, y2, x3, y3, x4, y4, step
  step ||= 0
  color = [200, 200, 200]
  points = points_for_bezier [x1, y1], [x2, y2], [x3, y3], [x4, y4], step

  points.each_cons(2).map do |p1, p2|
    [p1, p2, color]
  end
end

def points_for_bezier p1, p2, p3, p4, step
  points = []
  if step == 0
    [p1, p2, p3, p4]
  else
    t_step = 1.fdiv(step + 1)
    t = 0
    t += t_step
    points = []
    while t < 1
      points << [
        b_for_t(p1.x, p2.x, p3.x, p4.x, t),
        b_for_t(p1.y, p2.y, p3.y, p4.y, t),
      ]
      t += t_step
    end

    [
      p1,
      *points,
      p4
    ]
  end
end

def b_for_t v0, v1, v2, v3, t
  pow(1 - t, 3) * v0 +
  3 * pow(1 - t, 2) * t * v1 +
  3 * (1 - t) * pow(t, 2) * v2 +
  pow(t, 3) * v3
end

def pow n, to
  n ** to
end

    Easing Using Spline - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/03_easing_using_spline/app/main.rb
def tick args
  args.state.duration = 10.seconds
  args.state.spline = [
    [0.0, 0.33, 0.66, 1.0],
    [1.0, 1.0,  1.0,  1.0],
    [1.0, 0.66, 0.33, 0.0],
  ]

  args.state.simulation_tick = args.state.tick_count % args.state.duration
  progress = 0.ease_spline_extended args.state.simulation_tick, args.state.duration, args.state.spline
  args.outputs.borders << args.grid.rect
  args.outputs.solids << [20 + 1240 * progress,
                          20 +  680 * progress,
                          20, 20].anchor_rect(0.5, 0.5)
  args.outputs.labels << [10,
                          710,
                          "perc: #{"%.2f" % (args.state.simulation_tick / args.state.duration)} t: #{args.state.simulation_tick}"]
end

    Pulsing Button - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/04_pulsing_button/app/main.rb
# game concept from: https://youtu.be/Tz-AinJGDIM

# This class encapsulates the logic of a button that pulses when clicked.
# It is used in the StartScene and GameOverScene classes.
class PulseButton
  # a block is passed into the constructor and is called when the button is clicked,
  # and after the pulse animation is complete
  def initialize rect, text, &on_click
    @rect = rect
    @text = text
    @on_click = on_click
    @pulse_animation_spline = [[0.0, 0.90, 1.0, 1.0], [1.0, 0.10, 0.0, 0.0]]
    @duration = 10
  end

  # the button is ticked every frame and check to see if the mouse
  # intersects the button's bounding box.
  # if it does, then pertinent information is stored in the @clicked_at variable
  # which is used to calculate the pulse animation
  def tick tick_count, mouse
    @tick_count = tick_count

    if @clicked_at && @clicked_at.elapsed_time > @duration
      @clicked_at = nil
      @on_click.call
    end

    return if !mouse.click
    return if !mouse.inside_rect? @rect
    @clicked_at = tick_count
  end

  # this function returns an array of primitives that can be rendered
  def prefab easing
    # calculate the percentage of the pulse animation that has completed
    # and use the percentage to compute the size and position of the button
    perc = if @clicked_at
             easing.ease_spline @clicked_at, @tick_count, @duration, @pulse_animation_spline
           else
             0
           end

    rect = { x: @rect.x - 50 * perc / 2,
             y: @rect.y - 50 * perc / 2,
             w: @rect.w + 50 * perc,
             h: @rect.h + 50 * perc }

    point = { x: @rect.x + @rect.w / 2, y: @rect.y + @rect.h / 2 }
    [
      { **rect, path: :pixel },
      { **point, text: @text, size_px: 32, anchor_x: 0.5, anchor_y: 0.5 }
    ]
  end
end

class Game
  attr_gtk

  def initialize args
    self.args = args
    @pulse_button ||= PulseButton.new({ x: 640 - 100, y: 360 - 50, w: 200, h: 100 }, 'Click Me!') do
      $gtk.notify! "Animation complete and block invoked!"
    end
  end

  def tick
    @pulse_button.tick state.tick_count, inputs.mouse
    outputs.primitives << @pulse_button.prefab(easing)
  end
end

def tick args
  $game ||= Game.new args
  $game.args = args
  $game.tick
end

    Scene Transitions - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/05_scene_transitions/app/main.rb
# This sample app shows a more advanced implementation of scenes:
# 1. "Scene 1" has a label on it that says "I am scene ONE. Press enter to go to scene TWO."
# 2. "Scene 2" has a label on it that says "I am scene TWO. Press enter to go to scene ONE."
# 3. When the game starts, Scene 1 is presented.
# 4. When the player presses enter, the scene transitions to Scene 2 (fades out Scene 1 over half a second, then fades in Scene 2 over half a second).
# 5. When the player presses enter again, the scene transitions to Scene 1 (fades out Scene 2 over half a second, then fades in Scene 1 over half a second).
# 6. During the fade transitions, spamming the enter key is ignored (scenes don't accept a transition/respond to the enter key until the current transition is completed).
class SceneOne
  attr_gtk

  def tick
    outputs[:scene].transient!
    outputs[:scene].labels << { x: 640,
                                y: 360,
                                text: "I am scene ONE. Press enter to go to scene TWO.",
                                alignment_enum: 1,
                                vertical_alignment_enum: 1 }

    state.next_scene = :scene_two if inputs.keyboard.key_down.enter
  end
end

class SceneTwo
  attr_gtk

  def tick
    outputs[:scene].transient!
    outputs[:scene].labels << { x: 640,
                                y: 360,
                                text: "I am scene TWO. Press enter to go to scene ONE.",
                                alignment_enum: 1,
                                vertical_alignment_enum: 1 }

    state.next_scene = :scene_one if inputs.keyboard.key_down.enter
  end
end

class RootScene
  attr_gtk

  def initialize
    @scene_one = SceneOne.new
    @scene_two = SceneTwo.new
  end

  def tick
    defaults
    render
    tick_scene
  end

  def defaults
    set_current_scene! :scene_one if state.tick_count == 0
    state.scene_transition_duration ||= 30
  end

  def render
    a = if state.transition_scene_at
          255 * state.transition_scene_at.ease(state.scene_transition_duration, :flip)
        elsif state.current_scene_at
          255 * state.current_scene_at.ease(state.scene_transition_duration)
        else
          255
        end

    outputs.sprites << { x: 0, y: 0, w: 1280, h: 720, path: :scene, a: a }
  end

  def tick_scene
    current_scene = state.current_scene

    @current_scene.args = args
    @current_scene.tick

    if current_scene != state.current_scene
      raise "state.current_scene changed mid tick from #{current_scene} to #{state.current_scene}. To change scenes, set state.next_scene."
    end

    if state.next_scene && state.next_scene != state.transition_scene && state.next_scene != state.current_scene
      state.transition_scene_at = state.tick_count
      state.transition_scene = state.next_scene
    end

    if state.transition_scene_at && state.transition_scene_at.elapsed_time >= state.scene_transition_duration
      set_current_scene! state.transition_scene
    end

    state.next_scene = nil
  end

  def set_current_scene! id
    return if state.current_scene == id
    state.current_scene = id
    state.current_scene_at = state.tick_count
    state.transition_scene = nil
    state.transition_scene_at = nil

    if state.current_scene == :scene_one
      @current_scene = @scene_one
    elsif state.current_scene == :scene_two
      @current_scene = @scene_two
    end
  end
end

def tick args
  $game ||= RootScene.new
  $game.args = args
  $game.tick
end

    Animation Queues - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/06_animation_queues/app/main.rb
# here's how to create a "fire and forget" sprite animation queue
def tick args
  args.outputs.labels << { x: 640,
                           y: 360,
                           text: "Click anywhere on the screen.",
                           alignment_enum: 1,
                           vertical_alignment_enum: 1 }

  # initialize the queue to an empty array
  args.state.fade_out_queue ||=[]

  # if the mouse is click, add a sprite to the fire and forget
  # queue to be processed
  if args.inputs.mouse.click
    args.state.fade_out_queue << {
      x: args.inputs.mouse.x - 20,
      y: args.inputs.mouse.y - 20,
      w: 40,
      h: 40,
      path: "sprites/square/blue.png"
    }
  end

  # process the queue
  args.state.fade_out_queue.each do |item|
    # default the alpha value if it isn't specified
    item.a ||= 255

    # decrement the alpha by 5 each frame
    item.a -= 5
  end

  # remove the item if it's completely faded out
  args.state.fade_out_queue.reject! { |item| item.a <= 0 }

  # render the sprites in the queue
  args.outputs.sprites << args.state.fade_out_queue
end

    Animation Queues Advanced - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/07_animation_queues_advanced/app/main.rb
# sample app shows how to perform a fire and forget animation when a collision occurs
def tick args
  defaults args
  spawn_bullets args
  calc_bullets args
  render args
end

def defaults args
  # place a player on the far left with sprite and hp information
  args.state.player ||= { x: 100, y: 360 - 50, w: 100, h: 100, path: "sprites/square/blue.png", hp: 30 }
  # create an array of bullets
  args.state.bullets ||= []
  # create a queue for handling bullet explosions
  args.state.explosion_queue ||= []
end

def spawn_bullets args
  # span a bullet in a random location on the far right every half second
  return if !args.state.tick_count.zmod? 30
  args.state.bullets << {
    x: 1280 - 100,
    y: rand(720 - 100),
    w: 100,
    h: 100,
    path: "sprites/square/red.png"
  }
end

def calc_bullets args
  # for each bullet
  args.state.bullets.each do |b|
    # move it to the left by 20 pixels
    b.x -= 20

    # determine if the bullet collides with the player
    if b.intersect_rect? args.state.player
      # decrement the player's health if it does
      args.state.player.hp -= 1
      # mark the bullet as exploded
      b.exploded = true

      # queue the explosion by adding it to the explosion queue
      args.state.explosion_queue << b.merge(exploded_at: args.state.tick_count)
    end
  end

  # remove bullets that have exploded so they wont be rendered
  args.state.bullets.reject! { |b| b.exploded }

  # remove animations from the animation queue that have completed
  # frame index will return nil once the animation has completed
  args.state.explosion_queue.reject! { |e| !e.exploded_at.frame_index(7, 4, false) }
end

def render args
  # render the player's hp above the sprite
  args.outputs.labels << {
    x: args.state.player.x + 50,
    y: args.state.player.y + 110,
    text: "#{args.state.player.hp}",
    alignment_enum: 1,
    vertical_alignment_enum: 0
  }

  # render the player
  args.outputs.sprites << args.state.player

  # render the bullets
  args.outputs.sprites << args.state.bullets

  # process the animation queue
  args.outputs.sprites << args.state.explosion_queue.map do |e|
    number_of_frames = 7
    hold_each_frame_for = 4
    repeat_animation = false
    # use the exploded_at property and the frame_index function to determine when the animation should start
    frame_index = e.exploded_at.frame_index(number_of_frames, hold_each_frame_for, repeat_animation)
    # take the explosion primitive and set the path variariable
    e.merge path: "sprites/misc/explosion-#{frame_index}.png"
  end
end

    Cutscenes - main.rb link

    # ./samples/08_tweening_lerping_easing_functions/08_cutscenes/app/main.rb
# sample app shows how you can user a queue/callback mechanism to create cutscenes
class Game
  attr_gtk

  def initialize
    # this class controls the cutscene orchestration
    @tick_queue = TickQueue.new
  end

  def tick
    @tick_queue.args = args
    state.player ||= { x: 0, y: 0, w: 100, h: 100, path: :pixel, r: 0, g: 255, b: 0 }
    state.fade_to_black ||= 0
    state.back_and_forth_count ||= 0

    # if the mouse is clicked, start the cutscene
    if inputs.mouse.click && !state.cutscene_started
      start_cutscene
    end

    outputs.primitives << state.player
    outputs.primitives << { x: 0, y: 0, w: 1280, h: 720, path: :pixel, r: 0, g: 0, b: 0, a: state.fade_to_black }
    @tick_queue.tick
  end

  def start_cutscene
    # don't start the cutscene if it's already started
    return if state.cutscene_started
    state.cutscene_started = true

    # start the cutscene by moving right
    queue_move_to_right_side
  end

  def queue_move_to_right_side
    # use the tick queue mechanism to kick off the player moving right
    @tick_queue.queue_tick state.tick_count do |args, entry|
      state.player.x += 30
      # once the player is done moving right, stage the next step of the cutscene (moving left)
      if state.player.x + state.player.w > 1280
        state.player.x = 1280 - state.player.w
        queue_move_to_left_side

        # marke the queued tick entry as complete so it doesn't get run again
        entry.complete!
      end
    end
  end

  def queue_move_to_left_side
    # use the tick queue mechanism to kick off the player moving right
    @tick_queue.queue_tick state.tick_count do |args, entry|
      args.state.player.x -= 30
      # once the player id done moving left, decide on whether they should move right again or fade to black
      # the decision point is based on the number of times the player has moved left and right
      if args.state.player.x < 0
        state.player.x = 0
        args.state.back_and_forth_count += 1
        if args.state.back_and_forth_count < 3
          # if they haven't moved left and right 3 times, move them right again
          queue_move_to_right_side
        else
          # if they have moved left and right 3 times, fade to black
          queue_fade_to_black
        end

        # marke the queued tick entry as complete so it doesn't get run again
        entry.complete!
      end
    end
  end

  def queue_fade_to_black
    # we know the cutscene will end in 255 tickes, so we can queue a notification that will kick off in the future notifying that the cutscene is done
    @tick_queue.queue_one_time_tick state.tick_count + 255 do |args, entry|
      $gtk.notify "Cutscene complete!"
    end

    # start the fade to black
    @tick_queue.queue_tick state.tick_count do |args, entry|
      args.state.fade_to_black += 1
      entry.complete! if state.fade_to_black > 255
    end
  end
end

# this construct handles the execution of animations/cutscenes
# the key methods that are used are queue_tick and queue_one_time_tick
class TickQueue
  attr_gtk

  attr :queued_ticks
  attr :queued_ticks_currently_running

  def initialize
    @queued_ticks ||= {}
    @queued_ticks_currently_running ||= []
  end

  # adds a callback that will be processed
  def queue_tick at, &block
    @queued_ticks[at] ||= []
    @queued_ticks[at] << QueuedTick.new(at, &block)
  end

  # adds a callback that will be processed and immediately marked as complete
  def queue_one_time_tick at, **metadata, &block
    @queued_ticks ||= {}
    @queued_ticks[at] ||= []
    @queued_ticks[at] << QueuedOneTimeTick.new(at, &block)
  end

  def tick
    # get all queued callbacs that need to start running on the current frame
    entries_this_tick = @queued_ticks.delete args.state.tick_count

    # if there are values, then add them to the list of currently running callbacks
    if entries_this_tick
      @queued_ticks_currently_running.concat entries_this_tick
    end

    # run tick on each entry
    @queued_ticks_currently_running.each do |queued_tick|
      queued_tick.tick args
    end

    # remove all entries that are complete
    @queued_ticks_currently_running.reject!(&:complete?)

    # there is a chance that a queued tick will queue another tick, so we need to check
    # if there are any queued ticks for the current frame. if so, then recursively call tick again
    if @queued_ticks[args.state.tick_count] && @queued_ticks[args.state.tick_count].length > 0
      tick
    end
  end
end

# small data structure that holds the callback and status
# queue_tick constructs an instance of this class to faciltate
# the execution of the block and it's completion
class QueuedTick
  attr :queued_at, :block

  def initialize queued_at, &block
    @queued_at = queued_at
    @is_complete = false
    @block = block
  end

  def complete!
    @is_complete = true
  end

  def complete?
    @is_complete
  end

  def tick args
    @block.call args, self
  end
end

# small data structure that holds the callback and status
# queue_one_time_tick constructs an instance of this class to faciltate
# the execution of the block and it's completion
class QueuedOneTimeTick < QueuedTick
  def tick args
    @block.call args, self
    @is_complete = true
  end
end


$game = Game.new
def tick args
  $game.args = args
  $game.tick
end

$gtk.reset

    Performance link

    Sprites As Hash - main.rb link

    # ./samples/09_performance/01_sprites_as_hash/app/main.rb

# Sprites represented as Hashes using the queue ~args.outputs.sprites~
# code up, but are the "slowest" to render.
# The reason for this is the access of the key in the Hash and also
# because the data args.outputs.sprites is cleared every tick.
def random_x args
  (args.grid.w.randomize :ratio) * -1
end

def random_y args
  (args.grid.h.randomize :ratio) * -1
end

def random_speed
  1 + (4.randomize :ratio)
end

def new_star args
  {
    x: (random_x args),
    y: (random_y args),
    w: 4, h: 4, path: 'sprites/tiny-star.png',
    s: random_speed
  }
end

def move_star args, star
  star.x += star[:s]
  star.y += star[:s]
  if star.x > args.grid.w || star.y > args.grid.h
    star.x = (random_x args)
    star.y = (random_y args)
    star[:s] = random_speed
  end
end

def tick args
  args.state.star_count ||= 0

  # sets console command when sample app initially opens
  if Kernel.global_tick_count == 0
    puts ""
    puts ""
    puts "========================================================="
    puts "* INFO: Sprites, Hashes"
    puts "* INFO: Please specify the number of sprites to render."
    args.gtk.console.set_command "reset_with count: 100"
  end

  # init
  if args.state.tick_count == 0
    args.state.stars = args.state.star_count.map { |i| new_star args }
  end

  # update
  args.state.stars.each { |s| move_star args, s }

  # render
  args.outputs.sprites << args.state.stars
  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

# resets game, and assigns star count given by user
def reset_with count: count
  $gtk.reset
  $gtk.args.state.star_count = count
end

    Sprites As Entities - main.rb link

    # ./samples/09_performance/02_sprites_as_entities/app/main.rb
# Sprites represented as Entities using the queue ~args.outputs.sprites~
# yields nicer access apis over Hashes, but require a bit more code upfront.
# The hash sample has to use star[:s] to get the speed of the star, but
# an entity can use .s instead.
def random_x args
  (args.grid.w.randomize :ratio) * -1
end

def random_y args
  (args.grid.h.randomize :ratio) * -1
end

def random_speed
  1 + (4.randomize :ratio)
end

def new_star args
  args.state.new_entity :star, {
    x: (random_x args),
    y: (random_y args),
    w: 4, h: 4,
    path: 'sprites/tiny-star.png',
    s: random_speed
  }
end

def move_star args, star
  star.x += star.s
  star.y += star.s
  if star.x > args.grid.w || star.y > args.grid.h
    star.x = (random_x args)
    star.y = (random_y args)
    star.s = random_speed
  end
end

def tick args
  args.state.star_count ||= 0

  # sets console command when sample app initially opens
  if Kernel.global_tick_count == 0
    puts ""
    puts ""
    puts "========================================================="
    puts "* INFO: Sprites, Open Entities"
    puts "* INFO: Please specify the number of sprites to render."
    args.gtk.console.set_command "reset_with count: 100"
  end

  # init
  if args.state.tick_count == 0
    args.state.stars = args.state.star_count.map { |i| new_star args }
  end

  # update
  args.state.stars.each { |s| move_star args, s }

  # render
  args.outputs.sprites << args.state.stars
  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

# resets game, and assigns star count given by user
def reset_with count: count
  $gtk.reset
  $gtk.args.state.star_count = count
end

    Sprites As Strict Entities - main.rb link

    # ./samples/09_performance/04_sprites_as_strict_entities/app/main.rb
# Sprites represented as StrictEntities using the queue ~args.outputs.sprites~
# yields apis access similar to Entities, but all properties that can be set on the
# entity must be predefined with a default value. Strict entities do not support the
# addition of new properties after the fact. They are more performant than OpenEntities
# because of this constraint.
def random_x args
  (args.grid.w.randomize :ratio) * -1
end

def random_y args
  (args.grid.h.randomize :ratio) * -1
end

def random_speed
  1 + (4.randomize :ratio)
end

def new_star args
  args.state.new_entity_strict(:star,
                               x: (random_x args),
                               y: (random_y args),
                               w: 4, h: 4,
                               path: 'sprites/tiny-star.png',
                               s: random_speed) do |entity|
    # invoke attr_sprite so that it responds to
    # all properties that are required to render a sprite
    entity.attr_sprite
  end
end

def move_star args, star
  star.x += star.s
  star.y += star.s
  if star.x > args.grid.w || star.y > args.grid.h
    star.x = (random_x args)
    star.y = (random_y args)
    star.s = random_speed
  end
end

def tick args
  args.state.star_count ||= 0

  # sets console command when sample app initially opens
  if Kernel.global_tick_count == 0
    puts ""
    puts ""
    puts "========================================================="
    puts "* INFO: Sprites, Strict Entities"
    puts "* INFO: Please specify the number of sprites to render."
    args.gtk.console.set_command "reset_with count: 100"
  end

  # init
  if args.state.tick_count == 0
    args.state.stars = args.state.star_count.map { |i| new_star args }
  end

  # update
  args.state.stars.each { |s| move_star args, s }

  # render
  args.outputs.sprites << args.state.stars
  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

# resets game, and assigns star count given by user
def reset_with count: count
  $gtk.reset
  $gtk.args.state.star_count = count
end

    Sprites As Classes - main.rb link

    # ./samples/09_performance/05_sprites_as_classes/app/main.rb
# Sprites represented as Classes using the queue ~args.outputs.sprites~.
# gives you full control of property declaration and method invocation.
# They are more performant than OpenEntities and StrictEntities, but more code upfront.
class Star
  attr_sprite

  def initialize grid
    @grid = grid
    @x = (rand @grid.w) * -1
    @y = (rand @grid.h) * -1
    @w    = 4
    @h    = 4
    @s    = 1 + (4.randomize :ratio)
    @path = 'sprites/tiny-star.png'
  end

  def move
    @x += @s
    @y += @s
    @x = (rand @grid.w) * -1 if @x > @grid.right
    @y = (rand @grid.h) * -1 if @y > @grid.top
  end
end

# calls methods needed for game to run properly
def tick args
  # sets console command when sample app initially opens
  if Kernel.global_tick_count == 0
    puts ""
    puts ""
    puts "========================================================="
    puts "* INFO: Sprites, Classes"
    puts "* INFO: Please specify the number of sprites to render."
    args.gtk.console.set_command "reset_with count: 100"
  end

  args.state.star_count ||= 0

  # init
  if args.state.tick_count == 0
    args.state.stars = args.state.star_count.map { |i| Star.new args.grid }
  end

  # update
  args.state.stars.each(&:move)

  # render
  args.outputs.sprites << args.state.stars
  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

# resets game, and assigns star count given by user
def reset_with count: count
  $gtk.reset
  $gtk.args.state.star_count = count
end

    Static Sprites As Classes - main.rb link

    # ./samples/09_performance/06_static_sprites_as_classes/app/main.rb
# Sprites represented as Classes using the queue ~args.outputs.static_sprites~.
# bypasses the queue behavior of ~args.outputs.sprites~. All instances are held
# by reference. You get better performance, but you are mutating state of held objects
# which is less functional/data oriented.
class Star
  attr_sprite

  def initialize grid
    @grid = grid
    @x = (rand @grid.w) * -1
    @y = (rand @grid.h) * -1
    @w    = 4
    @h    = 4
    @s    = 1 + (4.randomize :ratio)
    @path = 'sprites/tiny-star.png'
  end

  def move
    @x += @s
    @y += @s
    @x = (rand @grid.w) * -1 if @x > @grid.right
    @y = (rand @grid.h) * -1 if @y > @grid.top
  end
end

# calls methods needed for game to run properly
def tick args
  # sets console command when sample app initially opens
  if Kernel.global_tick_count == 0
    puts ""
    puts ""
    puts "========================================================="
    puts "* INFO: Static Sprites, Classes"
    puts "* INFO: Please specify the number of sprites to render."
    args.gtk.console.set_command "reset_with count: 100"
  end

  args.state.star_count ||= 0

  # init
  if args.state.tick_count == 0
    args.state.stars = args.state.star_count.map { |i| Star.new args.grid }
    args.outputs.static_sprites << args.state.stars
  end

  # update
  args.state.stars.each(&:move)

  # render
  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

# resets game, and assigns star count given by user
def reset_with count: count
  $gtk.reset
  $gtk.args.state.star_count = count
end

    Static Sprites As Classes With Custom Drawing - main.rb link

    # ./samples/09_performance/07_static_sprites_as_classes_with_custom_drawing/app/main.rb
# Sprites represented as Classes, with a draw_override method, and using the queue ~args.outputs.static_sprites~.
# is the fastest approach. This is comparable to what other game engines set as the default behavior.
# There are tradeoffs for all this speed if the creation of a full blown class, and bypassing
# functional/data-oriented practices.
class Star
  def initialize grid
    @grid = grid
    @x = (rand @grid.w) * -1
    @y = (rand @grid.h) * -1
    @w    = 4
    @h    = 4
    @s    = 1 + (4.randomize :ratio)
    @path = 'sprites/tiny-star.png'
  end

  def move
    @x += @s
    @y += @s
    @x = (rand @grid.w) * -1 if @x > @grid.right
    @y = (rand @grid.h) * -1 if @y > @grid.top
  end

  # if the object that is in args.outputs.sprites (or static_sprites)
  # respond_to? :draw_override, then the method is invoked giving you
  # access to the class used to draw to the canvas.
  def draw_override ffi_draw
    # first move then draw
    move

    # The argument order for ffi.draw_sprite is:
    # x, y, w, h, path
    ffi_draw.draw_sprite @x, @y, @w, @h, @path

    # The argument order for ffi_draw.draw_sprite_2 is (pass in nil for default value):
    # x, y, w, h, path,
    # angle, alpha

    # The argument order for ffi_draw.draw_sprite_3 is:
    # x, y, w, h,
    # path,
    # angle,
    # alpha, red_saturation, green_saturation, blue_saturation
    # tile_x, tile_y, tile_w, tile_h,
    # flip_horizontally, flip_vertically,
    # angle_anchor_x, angle_anchor_y,
    # source_x, source_y, source_w, source_h

    # The argument order for ffi_draw.draw_sprite_4 is:
    # x, y, w, h,
    # path,
    # angle,
    # alpha, red_saturation, green_saturation, blue_saturation
    # tile_x, tile_y, tile_w, tile_h,
    # flip_horizontally, flip_vertically,
    # angle_anchor_x, angle_anchor_y,
    # source_x, source_y, source_w, source_h,
    # blendmode_enum

    # The argument order for ffi_draw.draw_sprite_5 is:
    # x, y, w, h,
    # path,
    # angle,
    # alpha, red_saturation, green_saturation, blue_saturation
    # tile_x, tile_y, tile_w, tile_h,
    # flip_horizontally, flip_vertically,
    # angle_anchor_x, angle_anchor_y,
    # source_x, source_y, source_w, source_h,
    # blendmode_enum
    # anchor_x
    # anchor_y
  end
end

# calls methods needed for game to run properly
def tick args
  # sets console command when sample app initially opens
  if Kernel.global_tick_count == 0
    puts ""
    puts ""
    puts "========================================================="
    puts "* INFO: Static Sprites, Classes, Draw Override"
    puts "* INFO: Please specify the number of sprites to render."
    args.gtk.console.set_command "reset_with count: 100"
  end

  args.state.star_count ||= 0

  # init
  if args.state.tick_count == 0
    args.state.stars = args.state.star_count.map { |i| Star.new args.grid }
    args.outputs.static_sprites << args.state.stars
  end

  # render framerate
  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

# resets game, and assigns star count given by user
def reset_with count: count
  $gtk.reset
  $gtk.args.state.star_count = count
end

    Collision Limits - main.rb link

    # ./samples/09_performance/08_collision_limits/app/main.rb
=begin

 Reminders:
 - find_all: Finds all elements of a collection that meet certain requirements.
   In this sample app, we're finding all bodies that intersect with the center body.

 - args.outputs.solids: An array. The values generate a solid.
   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.

 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - ARRAY#intersect_rect?: Returns true or false depending on if two rectangles intersect.

=end

# This code demonstrates moving objects that loop around once they exceed the scope of the screen,
# which has dimensions of 1280 by 720, and also detects collisions between objects called "bodies".

def body_count num
  $gtk.args.state.other_bodies = num.map { [1280 * rand, 720 * rand, 10, 10] } # other_bodies set using num collection
end

def tick args

  # Center body's values are set using an array
  # Map is used to set values of 5000 other bodies
  # All bodies that intersect with center body are stored in collisions collection
  args.state.center_body  ||= { x: 640 - 100, y: 360 - 100, w: 200, h: 200 } # calculations done to place body in center
  args.state.other_bodies ||= 5000.map do
    { x: 1280 * rand,
      y: 720 * rand,
      w: 2,
      h: 2,
      path: :pixel,
      r: 0,
      g: 0,
      b: 0 }
  end # 2000 bodies given random position on screen

  # finds all bodies that intersect with center body, stores them in collisions
  collisions = args.state.other_bodies.find_all { |b| b.intersect_rect? args.state.center_body }

  args.borders << args.state.center_body # outputs center body as a black border

  # transparency changes based on number of collisions; the more collisions, the redder (more transparent) the box becomes
  args.sprites  << { x: args.state.center_body.x,
                     y: args.state.center_body.y,
                     w: args.state.center_body.w,
                     h: args.state.center_body.h,
                     path: :pixel,
                     a: collisions.length.idiv(2), # alpha value represents the number of collisions that occured
                     r: 255,
                     g: 0,
                     b: 0 } # center body is red solid
  args.sprites  << args.state.other_bodies # other bodies are output as (black) solids, as well

  args.labels  << [10, 30, args.gtk.current_framerate.to_sf] # outputs frame rate in bottom left corner

  # Bodies are returned to bottom left corner if positions exceed scope of screen
  args.state.other_bodies.each do |b| # for each body in the other_bodies collection
    b.x += 5 # x and y are both incremented by 5
    b.y += 5
    b.x = 0 if b.x > 1280 # x becomes 0 if star exceeds scope of screen (goes too far right)
    b.y = 0 if b.y > 720 # y becomes 0 if star exceeds scope of screen (goes too far up)
  end
end

# Resets the game.
$gtk.reset

    Collision Limits Aabb - main.rb link

    # ./samples/09_performance/09_collision_limits_aabb/app/main.rb
def tick args
  args.state.id_seed    ||= 1
  args.state.bullets    ||= []
  args.state.terrain    ||= [
    {
      x: 40, y: 0, w: 1200, h: 40, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 1240, y: 0, w: 40, h: 720, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 0, y: 0, w: 40, h: 720, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 40, y: 680, w: 1200, h: 40, path: :pixel, r: 0, g: 0, b: 0
    },

    {
      x: 760, y: 420, w: 180, h: 40, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 720, y: 420, w: 40, h: 100, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 940, y: 420, w: 40, h: 100, path: :pixel, r: 0, g: 0, b: 0
    },

    {
      x: 660, y: 220, w: 280, h: 40, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 620, y: 220, w: 40, h: 100, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 940, y: 220, w: 40, h: 100, path: :pixel, r: 0, g: 0, b: 0
    },

    {
      x: 460, y: 40, w: 280, h: 40, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 420, y: 40, w: 40, h: 100, path: :pixel, r: 0, g: 0, b: 0
    },
    {
      x: 740, y: 40, w: 40, h: 100, path: :pixel, r: 0, g: 0, b: 0
    },
  ]

  if args.inputs.keyboard.space
      b = {
        id: args.state.id_seed,
        x: 60,
        y: 60,
        w: 10,
        h: 10,
        dy: rand(20) + 10,
        dx: rand(20) + 10,
        path: 'sprites/square/blue.png'
      }

      args.state.bullets << b # if b.id == 122

      args.state.id_seed += 1
  end

  terrain = args.state.terrain

  args.state.bullets.each do |b|
    next if b.still
    # if b.still
    #   x_dir = if rand > 0.5
    #             -1
    #           else
    #             1
    #           end

    #   y_dir = if rand > 0.5
    #             -1
    #           else
    #             1
    #           end

    #   b.dy = rand(20) + 10 * x_dir
    #   b.dx = rand(20) + 10 * y_dir
    #   b.still = false
    #   b.on_floor = false
    # end

    if b.on_floor
      b.dx *= 0.9
    end

    b.x += b.dx

    collision_x = args.geometry.find_intersect_rect(b, terrain)

    if collision_x
      if b.dx > 0
        b.x = collision_x.x - b.w
      elsif b.dx < 0
        b.x = collision_x.x + collision_x.w
      end
      b.dx *= -0.8
    end

    b.dy -= 0.25
    b.y += b.dy

    collision_y = args.geometry.find_intersect_rect(b, terrain)

    if collision_y
      if b.dy > 0
        b.y = collision_y.y - b.h
      elsif b.dy < 0
        b.y = collision_y.y + collision_y.h
      end

      if b.dy < 0 && b.dy.abs < 1
        b.on_floor = true
      end

      b.dy *= -0.8
    end

    if b.on_floor && (b.dy.abs + b.dx.abs) < 0.1
      b.still = true
    end
  end

  args.outputs.labels << { x: 60, y: 60.from_top, text: "Hold space bar to add squares." }
  args.outputs.labels << { x: 60, y: 90.from_top, text: "FPS: #{args.gtk.current_framerate.to_sf}" }
  args.outputs.labels << { x: 60, y: 120.from_top, text: "Count: #{args.state.bullets.length}" }
  args.outputs.borders << args.state.terrain
  args.outputs.sprites << args.state.bullets
end

# $gtk.reset

    Collision Limits Find Single - main.rb link

    # ./samples/09_performance/09_collision_limits_find_single/app/main.rb
def tick args
  if args.state.should_reset_framerate_calculation
    args.gtk.reset_framerate_calculation
    args.state.should_reset_framerate_calculation = nil
  end

  if !args.state.rects
    args.state.rects = []
    add_10_000_random_rects args
  end

  args.state.player_rect ||= { x: 640 - 20, y: 360 - 20, w: 40, h: 40 }
  args.state.collision_type ||= :using_lambda

  if args.state.tick_count == 0
    generate_scene args, args.state.quad_tree
  end

  # inputs
  # have a rectangle that can be moved around using arrow keys
  args.state.player_rect.x += args.inputs.left_right * 4
  args.state.player_rect.y += args.inputs.up_down * 4

  if args.inputs.mouse.click
    add_10_000_random_rects args
    args.state.should_reset_framerate_calculation = true
  end

  if args.inputs.keyboard.key_down.tab
    if args.state.collision_type == :using_lambda
      args.state.collision_type = :using_while_loop
    elsif args.state.collision_type == :using_while_loop
      args.state.collision_type = :using_find_intersect_rect
    elsif args.state.collision_type == :using_find_intersect_rect
      args.state.collision_type = :using_lambda
    end
    args.state.should_reset_framerate_calculation = true
  end

  # calc
  if args.state.collision_type == :using_lambda
    args.state.current_collision = args.state.rects.find { |r| r.intersect_rect? args.state.player_rect }
  elsif args.state.collision_type == :using_while_loop
    args.state.current_collision = nil
    idx = 0
    l = args.state.rects.length
    rects = args.state.rects
    player = args.state.player_rect
    while idx < l
      if rects[idx].intersect_rect? player
        args.state.current_collision = rects[idx]
        break
      end
      idx += 1
    end
  else
    args.state.current_collision = args.geometry.find_intersect_rect args.state.player_rect, args.state.rects
  end

  # render
  render_instructions args
  args.outputs.sprites << { x: 0, y: 0, w: 1280, h: 720, path: :scene }

  if args.state.current_collision
    args.outputs.sprites << args.state.current_collision.merge(path: :pixel, r: 255, g: 0, b: 0)
  end

  args.outputs.sprites << args.state.player_rect.merge(path: :pixel, a: 80, r: 0, g: 255, b: 0)
  args.outputs.labels  << {
    x: args.state.player_rect.x + args.state.player_rect.w / 2,
    y: args.state.player_rect.y + args.state.player_rect.h / 2,
    text: "player",
    alignment_enum: 1,
    vertical_alignment_enum: 1,
    size_enum: -4
  }

end

def add_10_000_random_rects args
  add_rects args, 10_000.map { { x: rand(1080) + 100, y: rand(520) + 100 } }
end

def add_rects args, points
  args.state.rects.concat(points.map { |point| { x: point.x, y: point.y, w: 5, h: 5 } })
  # args.state.quad_tree = args.geometry.quad_tree_create args.state.rects
  generate_scene args, args.state.quad_tree
end

def add_rect args, x, y
  args.state.rects << { x: x, y: y, w: 5, h: 5 }
  # args.state.quad_tree = args.geometry.quad_tree_create args.state.rects
  generate_scene args, args.state.quad_tree
end

def generate_scene args, quad_tree
  args.outputs[:scene].transient!
  args.outputs[:scene].w = 1280
  args.outputs[:scene].h = 720
  args.outputs[:scene].solids << { x: 0, y: 0, w: 1280, h: 720, r: 255, g: 255, b: 255 }
  args.outputs[:scene].sprites << args.state.rects.map { |r| r.merge(path: :pixel, r: 0, g: 0, b: 255) }
end

def render_instructions args
  args.outputs.primitives << { x:  0, y: 90.from_top, w: 1280, h: 100, r: 0, g: 0, b: 0, a: 200 }.solid!
  args.outputs.labels << { x: 10, y: 10.from_top, r: 255, g: 255, b: 255, size_enum: -2, text: "Click to add 10,000 random rects. Tab to change collision algorithm." }
  args.outputs.labels << { x: 10, y: 40.from_top, r: 255, g: 255, b: 255, size_enum: -2, text: "Algorithm: #{args.state.collision_type}" }
  args.outputs.labels << { x: 10, y: 55.from_top, r: 255, g: 255, b: 255, size_enum: -2, text: "Rect Count: #{args.state.rects.length}" }
  args.outputs.labels << { x: 10, y: 70.from_top, r: 255, g: 255, b: 255, size_enum: -2, text: "FPS: #{args.gtk.current_framerate.to_sf}" }
end

    Collision Limits Many To Many - main.rb link

    # ./samples/09_performance/09_collision_limits_many_to_many/app/main.rb
class Square
  attr_sprite

  def initialize
    @x    = rand 1280
    @y    = rand 720
    @w    = 15
    @h    = 15
    @path = 'sprites/square/blue.png'
    @dir = 1
  end

  def mark_collisions all
    @path = if all[self]
              'sprites/square/red.png'
            else
              'sprites/square/blue.png'
            end
  end

  def move
    @dir  = -1 if (@x + @w >= 1280) && @dir ==  1
    @dir  =  1 if (@x      <=    0) && @dir == -1
    @x   += @dir
  end
end

def reset_if_needed args
  if args.state.tick_count == 0 || args.inputs.mouse.click
    args.state.star_count = 1500
    args.state.stars = args.state.star_count.map { |i| Square.new }.to_a
    args.outputs.static_sprites.clear
    args.outputs.static_sprites << args.state.stars
  end
end

def tick args
  reset_if_needed args

  Fn.each args.state.stars do |s| s.move end

  all = GTK::Geometry.find_collisions args.state.stars
  Fn.each args.state.stars do |s| s.mark_collisions all end

  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

    Ui Controls link

    Checkboxes - main.rb link

    # ./samples/09_ui_controls/01_checkboxes/app/main.rb
def tick args
  # use layout apis to position check boxes
  args.state.checkboxes ||= [
    args.layout.rect(row: 0, col: 0, w: 1, h: 1).merge(id: :option1, text: "Option 1", checked: false, changed_at: -120),
    args.layout.rect(row: 1, col: 0, w: 1, h: 1).merge(id: :option1, text: "Option 2", checked: false, changed_at: -120),
    args.layout.rect(row: 2, col: 0, w: 1, h: 1).merge(id: :option1, text: "Option 3", checked: false, changed_at: -120),
    args.layout.rect(row: 3, col: 0, w: 1, h: 1).merge(id: :option1, text: "Option 4", checked: false, changed_at: -120),
  ]

  # check for click of checkboxes
  if args.inputs.mouse.click
    args.state.checkboxes.find_all do |checkbox|
      args.inputs.mouse.inside_rect? checkbox
    end.each do |checkbox|
      # mark checkbox value
      checkbox.checked = !checkbox.checked
      # set the time the checkbox was changed
      checkbox.changed_at = args.state.tick_count
    end
  end

  # render checkboxes
  args.outputs.primitives << args.state.checkboxes.map do |checkbox|
    # baseline prefab for checkbox
    prefab = {
      x: checkbox.x,
      y: checkbox.y,
      w: checkbox.w,
      h: checkbox.h
    }

    # label for checkbox centered vertically
    label = {
      x: checkbox.x + checkbox.w + 10,
      y: checkbox.y + checkbox.h / 2,
      text: checkbox.text,
      alignment_enum: 0,
      vertical_alignment_enum: 1
    }

    # rendering if checked or not
    if checkbox.checked
      # fade in
      a = 255 * args.easing.ease(checkbox.changed_at, args.state.tick_count, 30, :smooth_stop_quint)

      [
        label,
        prefab.merge(primitive_marker: :solid, a: a),
        prefab.merge(primitive_marker: :border)
      ]
    else
      # fade out
      a = 255 * args.easing.ease(checkbox.changed_at, args.state.tick_count, 30, :smooth_stop_quint, :flip)

      [
        label,
        prefab.merge(primitive_marker: :solid, a: a),
        prefab.merge(primitive_marker: :border)
      ]
    end
  end
end

    Advanced Debugging link

    Logging - main.rb link

    # ./samples/10_advanced_debugging/00_logging/app/main.rb
def tick args
  args.outputs.background_color = [255, 255, 255, 0]
  if args.state.tick_count == 0
    args.gtk.log_spam "log level spam"
    args.gtk.log_debug "log level debug"
    args.gtk.log_info "log level info"
    args.gtk.log_warn "log level warn"
    args.gtk.log_error "log level error"
    args.gtk.log_unfiltered "log level unfiltered"
    puts "This is a puts call"
    args.gtk.console.show
  end

  if args.state.tick_count == 60
    puts "This is a puts call on tick 60"
  elsif args.state.tick_count == 120
    puts "This is a puts call on tick 120"
  end
end

    Unit Tests - benchmark_api_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/benchmark_api_tests.rb
def test_benchmark_api args, assert
  result = args.gtk.benchmark iterations: 100,
                              only_one: -> () {
                                r = 0
                                (1..100).each do |i|
                                  r += 1
                                end
                              }

  assert.equal! result.first_place.name, :only_one

  result = args.gtk.benchmark iterations: 100,
                              iterations_100: -> () {
                                r = 0
                                (1..100).each do |i|
                                  r += 1
                                end
                              },
                              iterations_50: -> () {
                                r = 0
                                (1..50).each do |i|
                                  r += 1
                                end
                              }

  assert.equal! result.first_place.name, :iterations_50

  result = args.gtk.benchmark iterations: 1,
                              iterations_100: -> () {
                                r = 0
                                (1..100).each do |i|
                                  r += 1
                                end
                              },
                              iterations_50: -> () {
                                r = 0
                                (1..50).each do |i|
                                  r += 1
                                end
                              }

  assert.equal! result.too_small_to_measure, true
end

    Unit Tests - exception_raising_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/exception_raising_tests.rb
begin :shared
  class ExceptionalClass
    def initialize exception_to_throw = nil
      raise exception_to_throw if exception_to_throw
    end
  end
end

def test_exception_in_newing_object args, assert
  begin
    ExceptionalClass.new TypeError
    raise "Exception wasn't thrown!"
  rescue Exception => e
    assert.equal! e.class, TypeError, "Exceptions within constructor should be retained."
  end
end

    Unit Tests - fn_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/fn_tests.rb
def infinity
  1 / 0
end

def neg_infinity
  -1 / 0
end

def nan
  0.0 / 0
end

def test_add args, assert
  assert.equal! (args.fn.add), 0
  assert.equal! (args.fn.+), 0
  assert.equal! (args.fn.+ 1, 2, 3), 6
  assert.equal! (args.fn.+ 0), 0
  assert.equal! (args.fn.+ 0, nil), 0
  assert.equal! (args.fn.+ 0, nan), nil
  assert.equal! (args.fn.+ 0, nil, infinity), nil
  assert.equal! (args.fn.+ [1, 2, 3, [4, 5, 6]]), 21
  assert.equal! (args.fn.+ [nil, [4, 5, 6]]), 15
end

def test_sub args, assert
  neg_infinity = infinity * -1
  assert.equal! (args.fn.+), 0
  assert.equal! (args.fn.- 1, 2, 3), -4
  assert.equal! (args.fn.- 4), -4
  assert.equal! (args.fn.- 4, nan), nil
  assert.equal! (args.fn.- 0, nil), 0
  assert.equal! (args.fn.- 0, nil, infinity), nil
  assert.equal! (args.fn.- [0, 1, 2, 3, [4, 5, 6]]), -21
  assert.equal! (args.fn.- [nil, 0, [4, 5, 6]]), -15
end

def test_div args, assert
  assert.equal! (args.fn.div), 1
  assert.equal! (args.fn./), 1
  assert.equal! (args.fn./ 6, 3), 2
  assert.equal! (args.fn./ 6, infinity), nil
  assert.equal! (args.fn./ 6, nan), nil
  assert.equal! (args.fn./ infinity), nil
  assert.equal! (args.fn./ 0), nil
  assert.equal! (args.fn./ 6, [3]), 2
end

def test_idiv args, assert
  assert.equal! (args.fn.idiv), 1
  assert.equal! (args.fn.idiv 7, 3), 2
  assert.equal! (args.fn.idiv 6, infinity), nil
  assert.equal! (args.fn.idiv 6, nan), nil
  assert.equal! (args.fn.idiv infinity), nil
  assert.equal! (args.fn.idiv 0), nil
  assert.equal! (args.fn.idiv 7, [3]), 2
end

def test_mul args, assert
  assert.equal! (args.fn.mul), 1
  assert.equal! (args.fn.*), 1
  assert.equal! (args.fn.* 7, 3), 21
  assert.equal! (args.fn.* 6, nan), nil
  assert.equal! (args.fn.* 6, infinity), nil
  assert.equal! (args.fn.* infinity), nil
  assert.equal! (args.fn.* 0), 0
  assert.equal! (args.fn.* 7, [3]), 21
end

def test_acopy args, assert
  orig  = [1, 2, 3]
  clone = args.fn.acopy orig
  assert.equal! clone, [1, 2, 3]
  assert.equal! clone, orig
  assert.not_equal! clone.object_id, orig.object_id
end

def test_aget args, assert
  assert.equal! (args.fn.aget [:a, :b, :c], 1), :b
  assert.equal! (args.fn.aget [:a, :b, :c], nil), nil
  assert.equal! (args.fn.aget nil, 1), nil
end

def test_alength args, assert
  assert.equal! (args.fn.alength [:a, :b, :c]), 3
  assert.equal! (args.fn.alength nil), nil
end

def test_amap args, assert
  inc = lambda { |i| i + 1 }
  ary = [1, 2, 3]
  assert.equal! (args.fn.amap ary, inc), [2, 3, 4]
  assert.equal! (args.fn.amap nil, inc), nil
  assert.equal! (args.fn.amap ary, nil), nil
  assert.equal! (args.fn.amap ary, inc).class, Array
end

def test_and args, assert
  assert.equal! (args.fn.and 1, 2, 3, 4), 4
  assert.equal! (args.fn.and 1, 2, nil, 4), nil
  assert.equal! (args.fn.and), true
end

def test_or args, assert
  assert.equal! (args.fn.or 1, 2, 3, 4), 1
  assert.equal! (args.fn.or 1, 2, nil, 4), 1
  assert.equal! (args.fn.or), nil
  assert.equal! (args.fn.or nil, nil, false, 5, 10), 5
end

def test_eq_eq args, assert
  assert.equal! (args.fn.eq?), true
  assert.equal! (args.fn.eq? 1, 0), false
  assert.equal! (args.fn.eq? 1, 1, 1), true
  assert.equal! (args.fn.== 1, 1, 1), true
  assert.equal! (args.fn.== nil, nil), true
end

def test_apply args, assert
  assert.equal! (args.fn.and [nil, nil, nil]), [nil, nil, nil]
  assert.equal! (args.fn.apply [nil, nil, nil], args.fn.method(:and)), nil
  and_lambda = lambda {|*xs| args.fn.and(*xs)}
  assert.equal! (args.fn.apply [nil, nil, nil], and_lambda), nil
end

def test_areduce args, assert
  assert.equal! (args.fn.areduce [1, 2, 3], 0, lambda { |i, a| i + a }), 6
end

def test_array_hash args, assert
  assert.equal! (args.fn.array_hash :a, 1, :b, 2), { a: 1, b: 2 }
  assert.equal! (args.fn.array_hash), { }
end

    Unit Tests - gen_docs.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/gen_docs.rb
# ./dragonruby . --eval samples/10_advanced_debugging/03_unit_tests/gen_docs.rb --no-tick
# OR
# ./dragonruby ./samples/10_advanced_debugging/03_unit_tests --test gen_docs.rb
Kernel.export_docs!

    Unit Tests - geometry_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/geometry_tests.rb
begin :shared
  def primitive_representations x, y, w, h
    [
      [x, y, w, h],
      { x: x, y: y, w: w, h: h },
      RectForTest.new(x, y, w, h)
    ]
  end

  class RectForTest
    attr_sprite

    def initialize x, y, w, h
      @x = x
      @y = y
      @w = w
      @h = h
    end

    def to_s
      "RectForTest: #{[x, y, w, h]}"
    end
  end
end

begin :intersect_rect?
  def test_intersect_rect_point args, assert
    assert.true! [16, 13].intersect_rect?([13, 12, 4, 4]), "point intersects with rect."
  end

  def test_intersect_rect args, assert
    intersecting = primitive_representations(0, 0, 100, 100) +
                   primitive_representations(20, 20, 20, 20)

    intersecting.product(intersecting).each do |rect_one, rect_two|
      assert.true! rect_one.intersect_rect?(rect_two),
                   "intersect_rect? assertion failed for #{rect_one}, #{rect_two} (expected true)."
    end

    not_intersecting = [
      [ 0, 0, 5, 5],
      { x: 10, y: 10, w: 5, h: 5 },
      RectForTest.new(20, 20, 5, 5)
    ]

    not_intersecting.product(not_intersecting)
      .reject { |rect_one, rect_two| rect_one == rect_two }
      .each do |rect_one, rect_two|
      assert.false! rect_one.intersect_rect?(rect_two),
                    "intersect_rect? assertion failed for #{rect_one}, #{rect_two} (expected false)."
    end
  end
end

begin :inside_rect?
  def assert_inside_rect outer: nil, inner: nil, expected: nil, assert: nil
    assert.true! inner.inside_rect?(outer) == expected,
                 "inside_rect? assertion failed for outer: #{outer} inner: #{inner} (expected #{expected})."
  end

  def test_inside_rect args, assert
    outer_rects = primitive_representations(0, 0, 10, 10)
    inner_rects = primitive_representations(1, 1, 5, 5)
    primitive_representations(0, 0, 10, 10).product(primitive_representations(1, 1, 5, 5))
      .each do |outer, inner|
      assert_inside_rect outer: outer, inner: inner,
                         expected: true, assert: assert
    end
  end
end

begin :angle_to
  def test_angle_to args, assert
    origins = primitive_representations(0, 0, 0, 0)
    rights = primitive_representations(1, 0, 0, 0)
    aboves = primitive_representations(0, 1, 0, 0)

    origins.product(aboves).each do |origin, above|
      assert.equal! origin.angle_to(above), 90,
                    "A point directly above should be 90 degrees."

      assert.equal! above.angle_from(origin), 90,
                    "A point coming from above should be 90 degrees."
    end

    origins.product(rights).each do |origin, right|
      assert.equal! origin.angle_to(right) % 360, 0,
                    "A point directly to the right should be 0 degrees."

      assert.equal! right.angle_from(origin) % 360, 0,
                    "A point coming from the right should be 0 degrees."

    end
  end
end

begin :scale_rect
  def test_scale_rect args, assert
    assert.equal! [0, 0, 100, 100].scale_rect(0.5, 0.5),
                  [25.0, 25.0, 50.0, 50.0]

    assert.equal! [0, 0, 100, 100].scale_rect(0.5),
                  [0.0, 0.0, 50.0, 50.0]

    assert.equal! [0, 0, 100, 100].scale_rect_extended(percentage_x: 0.5, percentage_y: 0.5, anchor_x: 0.5, anchor_y: 0.5),
                  [25.0, 25.0, 50.0, 50.0]

    assert.equal! [0, 0, 100, 100].scale_rect_extended(percentage_x: 0.5, percentage_y: 0.5, anchor_x: 0, anchor_y: 0),
                  [0.0, 0.0, 50.0, 50.0]
  end
end

    Unit Tests - http_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/http_tests.rb
def try_assert_or_schedule args, assert
  if $result[:complete]
    log_info "Request completed! Verifying."
    if $result[:http_response_code] != 200
      log_info "The request yielded a result of #{$result[:http_response_code]} instead of 200."
      exit
    end
    log_info ":try_assert_or_schedule succeeded!"
  else
    args.gtk.schedule_callback Kernel.tick_count + 10 do
      try_assert_or_schedule args, assert
    end
  end
end

def test_http args, assert
  $result = $gtk.http_get 'http://dragonruby.org'
  try_assert_or_schedule args, assert
end

    Unit Tests - input_emulation_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/input_emulation_tests.rb
def test_keyboard args, assert
  args.inputs.keyboard.key_down.i = true
  assert.true! args.inputs.keyboard.truthy_keys.include?(:i)
end

    Unit Tests - nil_coercion_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/nil_coercion_tests.rb
# numbers
def test_open_entity_add_number args, assert
  assert.nil! args.state.i_value
  args.state.i_value += 5
  assert.equal! args.state.i_value, 5

  assert.nil! args.state.f_value
  args.state.f_value += 5.5
  assert.equal! args.state.f_value, 5.5
end

def test_open_entity_subtract_number args, assert
  assert.nil! args.state.i_value
  args.state.i_value -= 5
  assert.equal! args.state.i_value, -5

  assert.nil! args.state.f_value
  args.state.f_value -= 5.5
  assert.equal! args.state.f_value, -5.5
end

def test_open_entity_multiply_number args, assert
  assert.nil! args.state.i_value
  args.state.i_value *= 5
  assert.equal! args.state.i_value, 0

  assert.nil! args.state.f_value
  args.state.f_value *= 5.5
  assert.equal! args.state.f_value, 0
end

def test_open_entity_divide_number args, assert
  assert.nil! args.state.i_value
  args.state.i_value /= 5
  assert.equal! args.state.i_value, 0

  assert.nil! args.state.f_value
  args.state.f_value /= 5.5
  assert.equal! args.state.f_value, 0
end

# array
def test_open_entity_add_array args, assert
  assert.nil! args.state.values
  args.state.values += [:a, :b, :c]
  assert.equal! args.state.values, [:a, :b, :c]
end

def test_open_entity_subtract_array args, assert
  assert.nil! args.state.values
  args.state.values -= [:a, :b, :c]
  assert.equal! args.state.values, []
end

def test_open_entity_shovel_array args, assert
  assert.nil! args.state.values
  args.state.values << :a
  assert.equal! args.state.values, [:a]
end

def test_open_entity_enumerate args, assert
  assert.nil! args.state.values
  args.state.values = args.state.values.map_with_index { |i| i }
  assert.equal! args.state.values, []

  assert.nil! args.state.values_2
  args.state.values_2 = args.state.values_2.map { |i| i }
  assert.equal! args.state.values_2, []

  assert.nil! args.state.values_3
  args.state.values_3 = args.state.values_3.flat_map { |i| i }
  assert.equal! args.state.values_3, []
end

# hashes
def test_open_entity_indexer args, assert
  GTK::Entity.__reset_id__!
  assert.nil! args.state.values
  args.state.values[:test] = :value
  assert.equal! args.state.values.to_s, { entity_id: 1, entity_name: :values, entity_keys_by_ref: {}, test: :value }.to_s
end

# bug
def test_open_entity_nil_bug args, assert
  GTK::Entity.__reset_id__!
  args.state.foo.a
  args.state.foo.b
  @hello[:foobar]
  assert.nil! args.state.foo.a, "a was not nil."
  # the line below fails
  # assert.nil! args.state.foo.b, "b was not nil."
end

    Unit Tests - object_to_primitive_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/object_to_primitive_tests.rb
class PlayerSpriteForTest
end

def test_array_to_sprite args, assert
  array = [[0, 0, 100, 100, "test.png"]].sprites
  puts "No exception was thrown. Sweet!"
end

def test_class_to_sprite args, assert
  array = [PlayerSprite.new].sprites
  assert.true! array.first.is_a?(PlayerSprite)
  puts "No exception was thrown. Sweet!"
end

    Unit Tests - parsing_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/parsing_tests.rb
def test_parse_json args, assert
  result = args.gtk.parse_json '{ "name": "John Doe", "aliases": ["JD"] }'
  assert.equal! result, { "name"=>"John Doe", "aliases"=>["JD"] }, "Parsing JSON failed."
end

def test_parse_xml args, assert
  result = args.gtk.parse_xml <<-S
<Person id="100">
  <Name>John Doe</Name>
</Person>
S

 expected = {:type=>:element,
             :name=>nil,
             :children=>[{:type=>:element,
                          :name=>"Person",
                          :children=>[{:type=>:element,
                                       :name=>"Name",
                                       :children=>[{:type=>:content,
                                                    :data=>"John Doe"}]}],
                          :attributes=>{"id"=>"100"}}]}

 assert.equal! result, expected, "Parsing xml failed."
end

    Unit Tests - pretty_format_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/pretty_format_tests.rb
def H opts
  opts
end

def A *opts
  opts
end

def assert_format args, assert, hash, expected
  actual = args.fn.pretty_format hash
  assert.are_equal! actual, expected
end

def test_pretty_print args, assert
  # =============================
  # hash with single value
  # =============================
  input = (H first_name: "John")
  expected = <<-S
{:first_name "John"}
S
  (assert_format args, assert, input, expected)

  # =============================
  # hash with two values
  # =============================
  input = (H first_name: "John", last_name: "Smith")
  expected = <<-S
{:first_name "John"
 :last_name "Smith"}
S

  (assert_format args, assert, input, expected)

  # =============================
  # hash with inner hash
  # =============================
  input = (H first_name: "John",
             last_name: "Smith",
             middle_initial: "I",
             so: (H first_name: "Pocahontas",
                    last_name: "Tsenacommacah"),
             friends: (A (H first_name: "Side", last_name: "Kick"),
                         (H first_name: "Tim", last_name: "Wizard")))
  expected = <<-S
{:first_name "John"
 :last_name "Smith"
 :middle_initial "I"
 :so {:first_name "Pocahontas"
      :last_name "Tsenacommacah"}
 :friends [{:first_name "Side"
            :last_name "Kick"}
           {:first_name "Tim"
            :last_name "Wizard"}]}
S

  (assert_format args, assert, input, expected)

  # =============================
  # array with one value
  # =============================
  input = (A 1)
  expected = <<-S
[1]
S
  (assert_format args, assert, input, expected)

  # =============================
  # array with multiple values
  # =============================
  input = (A 1, 2, 3)
  expected = <<-S
[1
 2
 3]
S
  (assert_format args, assert, input, expected)

  # =============================
  # array with multiple values hashes
  # =============================
  input = (A (H first_name: "Side", last_name: "Kick"),
             (H first_name: "Tim", last_name: "Wizard"))
  expected = <<-S
[{:first_name "Side"
  :last_name "Kick"}
 {:first_name "Tim"
  :last_name "Wizard"}]
S

  (assert_format args, assert, input, expected)
end

def test_nested_nested args, assert
  # =============================
  # nested array in nested hash
  # =============================
  input = (H type: :root,
             text: "Root",
             children: (A (H level: 1,
                             text: "Level 1",
                             children: (A (H level: 2,
                                             text: "Level 2",
                                             children: [])))))

  expected = <<-S
{:type :root
 :text "Root"
 :children [{:level 1
             :text "Level 1"
             :children [{:level 2
                         :text "Level 2"
                         :children []}]}]}

S

  (assert_format args, assert, input, expected)
end

def test_scene args, assert
  script = <<-S
* Scene 1
** Narrator
They say happy endings don't exist.
** Narrator
They say true love is a lie.
S
  input = parse_org args, script
  puts (args.fn.pretty_format input)
end

    Unit Tests - require_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/require_tests.rb
def write_src path, src
  $gtk.write_file path, src
end

write_src 'app/unit_testing_game.rb', <<-S
module UnitTesting
  class Game
  end
end
S

write_src 'lib/unit_testing_lib.rb', <<-S
module UnitTesting
  class Lib
  end
end
S

write_src 'app/nested/unit_testing_nested.rb', <<-S
module UnitTesting
  class Nested
  end
end
S

require 'app/unit_testing_game.rb'
require 'app/nested/unit_testing_nested.rb'
require 'lib/unit_testing_lib.rb'

def test_require args, assert
  UnitTesting::Game.new
  UnitTesting::Lib.new
  UnitTesting::Nested.new
  $gtk.exec 'rm ./mygame/app/unit_testing_game.rb'
  $gtk.exec 'rm ./mygame/app/nested/unit_testing_nested.rb'
  $gtk.exec 'rm ./mygame/lib/unit_testing_lib.rb'
  assert.ok!
end

    Unit Tests - serialize_deserialize_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/serialize_deserialize_tests.rb
def assert_hash_strings! assert, string_1, string_2
  Kernel.eval("$assert_hash_string_1 = #{string_1}")
  Kernel.eval("$assert_hash_string_2 = #{string_2}")
  assert.equal! $assert_hash_string_1, $assert_hash_string_2
end


def test_serialize args, assert
  args.state.player_one = "test"
  result = args.gtk.serialize_state args.state
  assert_hash_strings! assert, result, "{:entity_id=>1, :entity_keys_by_ref=>{}, :tick_count=>-1, :player_one=>\"test\"}"

  args.gtk.write_file 'state.txt', ''
  result = args.gtk.serialize_state 'state.txt', args.state
  assert_hash_strings! assert, result, "{:entity_id=>1, :entity_keys_by_ref=>{}, :tick_count=>-1, :player_one=>\"test\"}"
end

def test_deserialize args, assert
  result = args.gtk.deserialize_state '{:entity_id=>3, :tick_count=>-1, :player_one=>"test"}'
  assert.equal! result.player_one, "test"

  args.gtk.write_file 'state.txt',  '{:entity_id=>3, :tick_count=>-1, :player_one=>"test"}'
  result = args.gtk.deserialize_state 'state.txt'
  assert.equal! result.player_one, "test"
end

def test_very_large_serialization args, assert
  args.gtk.write_file("logs/log.txt", "")
  size = 3000
  size.map_with_index do |i|
    args.state.send("k#{i}=".to_sym, i)
  end

  result = args.gtk.serialize_state args.state
  assert.true! $serialize_state_serialization_too_large
end

def test_strict_entity_serialization args, assert
  args.state.player_one = args.state.new_entity(:player, name: "Ryu")
  args.state.player_two = args.state.new_entity_strict(:player_strict, name: "Ken")

  serialized_state = args.gtk.serialize_state args.state
  assert_hash_strings! assert, serialized_state, '{:entity_id=>1, :entity_keys_by_ref=>{}, :tick_count=>-1, :player_one=>{:entity_id=>3, :entity_name=>:player, :entity_keys_by_ref=>{}, :entity_type=>:player, :created_at=>-1, :global_created_at=>-1, :name=>"Ryu"}, :player_two=>{:entity_id=>5, :entity_name=>:player_strict, :entity_type=>:player_strict, :created_at=>-1, :global_created_at_elapsed=>-1, :entity_strict=>true, :entity_keys_by_ref=>{}, :name=>"Ken"}}'

  deserialize_state = args.gtk.deserialize_state serialized_state

  assert.equal! args.state.player_one.name, deserialize_state.player_one.name
  assert.true! args.state.player_one.is_a? GTK::OpenEntity

  assert.equal! args.state.player_two.name, deserialize_state.player_two.name
  assert.true! args.state.player_two.is_a? GTK::StrictEntity
end

def test_strict_entity_serialization_with_nil args, assert
  args.state.player_one = args.state.new_entity(:player, name: "Ryu")
  args.state.player_two = args.state.new_entity_strict(:player_strict, name: "Ken", blood_type: nil)

  serialized_state = args.gtk.serialize_state args.state
  assert_hash_strings! assert, serialized_state, '{:entity_id=>1, :entity_keys_by_ref=>{}, :tick_count=>-1, :player_one=>{:entity_id=>3, :entity_name=>:player, :entity_keys_by_ref=>{}, :entity_type=>:player, :created_at=>-1, :global_created_at=>-1, :name=>"Ryu"}, :player_two=>{:entity_name=>:player_strict, :global_created_at_elapsed=>-1, :created_at=>-1, :blood_type=>nil, :name=>"Ken", :entity_type=>:player_strict, :entity_strict=>true, :entity_keys_by_ref=>{}, :entity_id=>4}}'

  deserialized_state = args.gtk.deserialize_state serialized_state

  assert.equal! args.state.player_one.name, deserialized_state.player_one.name
  assert.true! args.state.player_one.is_a? GTK::OpenEntity

  assert.equal! args.state.player_two.name, deserialized_state.player_two.name
  assert.equal! args.state.player_two.blood_type, deserialized_state.player_two.blood_type
  assert.equal! deserialized_state.player_two.blood_type, nil
  assert.true! args.state.player_two.is_a? GTK::StrictEntity

  deserialized_state.player_two.blood_type = :O
  assert.equal! deserialized_state.player_two.blood_type, :O
end

def test_multiple_strict_entities args, assert
  args.state.player = args.state.new_entity_strict(:player_one, name: "Ryu")
  args.state.enemy = args.state.new_entity_strict(:enemy, name: "Bison", other_property: 'extra mean')

  serialized_state = args.gtk.serialize_state args.state

  deserialized_state = args.gtk.deserialize_state serialized_state

  assert.equal! deserialized_state.player.name, "Ryu"
  assert.equal! deserialized_state.enemy.other_property, "extra mean"
end

def test_by_reference_state args, assert
  args.state.a = args.state.new_entity(:person, name: "Jane Doe")
  args.state.b = args.state.a
  assert.equal! args.state.a.object_id, args.state.b.object_id
  serialized_state = args.gtk.serialize_state args.state

  deserialized_state = args.gtk.deserialize_state serialized_state
  assert.equal! deserialized_state.a.object_id, deserialized_state.b.object_id
end

def test_by_reference_state_strict_entities args, assert
  args.state.strict_entity = args.state.new_entity_strict(:couple) do |e|
    e.one = args.state.new_entity_strict(:person, name: "Jane")
    e.two = e.one
  end
  assert.equal! args.state.strict_entity.one, args.state.strict_entity.two
  serialized_state = args.gtk.serialize_state args.state

  deserialized_state = args.gtk.deserialize_state serialized_state
  assert.equal! deserialized_state.strict_entity.one, deserialized_state.strict_entity.two
end

def test_serialization_excludes_thrash_count args, assert
  args.state.player.name = "Ryu"
  # force a nil pun
  if args.state.player.age > 30
  end
  assert.equal! args.state.player.as_hash[:__thrash_count__][:>], 1
  result = args.gtk.serialize_state args.state
  assert.false! (result.include? "__thrash_count__"),
                "The __thrash_count__ key exists in state when it shouldn't have."
end

def test_serialization_does_not_mix_up_zero_and_true args, assert
  args.state.enemy.evil = true
  args.state.enemy.hp = 0
  serialized = args.gtk.serialize_state args.state.enemy

  deserialized = args.gtk.deserialize_state serialized

  assert.equal! deserialized.hp, 0,
                "Value should have been deserialized as 0, but was #{deserialized.hp}"
  assert.equal! deserialized.evil, true,
                "Value should have been deserialized as true, but was #{deserialized.evil}"
end

    Unit Tests - state_serialization_experimental_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/state_serialization_experimental_tests.rb
MAX_CODE_GEN_LENGTH = 50

# NOTE: This is experimental/advanced stuff.
def needs_partitioning? target
  target[:value].to_s.length > MAX_CODE_GEN_LENGTH
end

def partition target
  return [] unless needs_partitioning? target
  if target[:value].is_a? GTK::OpenEntity
    target[:value] = target[:value].hash
  end

  results = []
  idx = 0
  left, right = target[:value].partition do
    idx += 1
    idx.even?
  end
  left, right = Hash[left], Hash[right]
  left = { value: left }
  right = { value: right}
  [left, right]
end

def add_partition target, path, aggregate, final_result
  partitions = partition target
  partitions.each do |part|
    if needs_partitioning? part
      if part[:value].keys.length == 1
        first_key = part[:value].keys[0]
        new_part = { value: part[:value][first_key] }
        path.push first_key
        add_partition new_part, path, aggregate, final_result
        path.pop
      else
        add_partition part, path, aggregate, final_result
      end
    else
      final_result << { value: { __path__: [*path] } }
      final_result << { value: part[:value] }
    end
  end
end

def state_to_string state
  parts_queue = []
  final_queue = []
  add_partition({ value: state.hash },
                [],
                parts_queue,
                final_queue)
  final_queue.reject {|i| i[:value].keys.length == 0}.map do |i|
    i[:value].to_s
  end.join("\n#==================================================#\n")
end

def state_from_string string
  Kernel.eval("$load_data = {}")
  lines = string.split("\n#==================================================#\n")
  lines.each do |l|
    puts "todo: #{l}"
  end

  GTK::OpenEntity.parse_from_hash $load_data
end

def test_save_and_load args, assert
  args.state.item_1.name = "Jane"
  string = state_to_string args.state
  state = state_from_string string
  assert.equal! args.state.item_1.name, state.item_1.name
end

def test_save_and_load_big args, assert
  size = 1000
  size.map_with_index do |i|
    args.state.send("k#{i}=".to_sym, i)
  end

  string = state_to_string args.state
  state = state_from_string string
  size.map_with_index do |i|
    assert.equal! args.state.send("k#{i}".to_sym), state.send("k#{i}".to_sym)
    assert.equal! args.state.send("k#{i}".to_sym), i
    assert.equal! state.send("k#{i}".to_sym), i
  end
end

def test_save_and_load_big_nested args, assert
  args.state.player_one.friend.nested_hash.k0 = 0
  args.state.player_one.friend.nested_hash.k1 = 1
  args.state.player_one.friend.nested_hash.k2 = 2
  args.state.player_one.friend.nested_hash.k3 = 3
  args.state.player_one.friend.nested_hash.k4 = 4
  args.state.player_one.friend.nested_hash.k5 = 5
  args.state.player_one.friend.nested_hash.k6 = 6
  args.state.player_one.friend.nested_hash.k7 = 7
  args.state.player_one.friend.nested_hash.k8 = 8
  args.state.player_one.friend.nested_hash.k9 = 9
  string = state_to_string args.state
  state = state_from_string string
end

    Unit Tests - suggest_autocompletion_tests.rb link

    # ./samples/10_advanced_debugging/03_unit_tests/suggest_autocompletion_tests.rb
def default_suggest_autocompletion args
  {
    index: 4,
    text: "args.",
    __meta__: {
      other_options: [
        {
          index: Fixnum,
          file: "app/main.rb"
        }
      ]
    }
  }
end

def assert_completion source, *expected
  results = suggest_autocompletion text:  (source.strip.gsub  ":cursor", ""),
                                   index: (source.strip.index ":cursor")

  puts results
end

def test_args_completion args, assert
  $gtk.write_file_root "autocomplete.txt", ($gtk.suggest_autocompletion text: <<-S, index: 128).join("\n")
require 'app/game.rb'

def tick args
  args.gtk.suppress_mailbox = false
  $game ||= Game.new
  $game.args = args
  $game.args.
  $game.tick
end
S

  puts "contents:"
  puts ($gtk.read_file "autocomplete.txt")
end

    Http link

    Retrieve Images - main.rb link

    # ./samples/11_http/01_retrieve_images/app/main.rb
$gtk.register_cvar 'app.warn_seconds', "seconds to wait before starting", :uint, 11

def tick args
  args.outputs.background_color = [0, 0, 0]

  # Show a warning at the start.
  args.state.warning_debounce ||= args.cvars['app.warn_seconds'].value * 60
  if args.state.warning_debounce > 0
    args.state.warning_debounce -= 1
    args.outputs.labels << [640, 600, "This app shows random images from the Internet.", 10, 1, 255, 255, 255]
    args.outputs.labels << [640, 500, "Quit in the next few seconds if this is a problem.", 10, 1, 255, 255, 255]
    args.outputs.labels << [640, 350, "#{(args.state.warning_debounce / 60.0).to_i}", 10, 1, 255, 255, 255]
    return
  end

  args.state.download_debounce ||= 0   # start immediately, reset to non zero later.
  args.state.photos ||= []

  # Put a little pause between each download.
  if args.state.download.nil?
    if args.state.download_debounce > 0
      args.state.download_debounce -= 1
    else
      args.state.download = $gtk.http_get 'https://picsum.photos/200/300.jpg'
    end
  end

  if !args.state.download.nil?
    if args.state.download[:complete]
      if args.state.download[:http_response_code] == 200
        fname = "sprites/#{args.state.photos.length}.jpg"
        $gtk.write_file fname, args.state.download[:response_data]
        args.state.photos << [ 100 + rand(1080), 500 - rand(480), fname, rand(80) - 40 ]
      end
      args.state.download = nil
      args.state.download_debounce = (rand(3) + 2) * 60
    end
  end

  # draw any downloaded photos...
  args.state.photos.each { |i|
    args.outputs.primitives << [i[0], i[1], 200, 300, i[2], i[3]].sprite
  }

  # Draw a download progress bar...
  args.outputs.primitives << [0, 0, 1280, 30, 0, 0, 0, 255].solid
  if !args.state.download.nil?
    br = args.state.download[:response_read]
    total = args.state.download[:response_total]
    if total != 0
      pct = br.to_f / total.to_f
      args.outputs.primitives << [0, 0, 1280 * pct, 30, 0, 0, 255, 255].solid
    end
  end
end

    In Game Web Server Http Get - main.rb link

    # ./samples/11_http/02_in_game_web_server_http_get/app/main.rb
def tick args
  args.state.port ||= 3000
  args.state.reqnum ||= 0
  # by default the embedded webserver runs on port 9001 (the port number is over 9000) and is disabled in a production build
  # to enable the http server in a production build, you need to manually start
  # the server up:
  args.gtk.start_server! port: args.state.port, enable_in_prod: true
  args.outputs.background_color = [0, 0, 0]
  args.outputs.labels << [640, 600, "Point your web browser at http://localhost:#{args.state.port}/", 10, 1, 255, 255, 255]

  if args.state.tick_count == 1
    $gtk.openurl "http://localhost:3000"
  end

  args.inputs.http_requests.each { |req|
    puts("METHOD: #{req.method}");
    puts("URI: #{req.uri}");
    puts("HEADERS:");
    req.headers.each { |k,v| puts("  #{k}: #{v}") }

    if (req.uri == '/')
      # headers and body can be nil if you don't care about them.
      # If you don't set the Content-Type, it will default to
      #  "text/html; charset=utf-8".
      # Don't set Content-Length; we'll ignore it and calculate it for you
      args.state.reqnum += 1
      req.respond 200, "<html><head><title>hello</title></head><body><h1>This #{req.method} was request number #{args.state.reqnum}!</h1></body></html>\n", { 'X-DRGTK-header' => 'Powered by DragonRuby!' }
    else
      req.reject
    end
  }
end

    In Game Web Server Http Post - main.rb link

    # ./samples/11_http/03_in_game_web_server_http_post/app/main.rb
def tick args
  # defaults
  args.state.post_button      = args.layout.rect(row: 0, col: 0, w: 5, h: 1).merge(text: "execute http_post")
  args.state.post_body_button = args.layout.rect(row: 1, col: 0, w: 5, h: 1).merge(text: "execute http_post_body")
  args.state.request_to_s ||= ""
  args.state.request_body ||= ""

  # render
  args.state.post_button.yield_self do |b|
    args.outputs.borders << b
    args.outputs.labels  << b.merge(text: b.text,
                                    y:    b.y + 30,
                                    x:    b.x + 10)
  end

  args.state.post_body_button.yield_self do |b|
    args.outputs.borders << b
    args.outputs.labels  << b.merge(text: b.text,
                                    y:    b.y + 30,
                                    x:    b.x + 10)
  end

  draw_label args, 0,  6, "Request:", args.state.request_to_s
  draw_label args, 0, 14, "Request Body Unaltered:", args.state.request_body

  # input
  if args.inputs.mouse.click
    # ============= HTTP_POST =============
    if (args.inputs.mouse.inside_rect? args.state.post_button)
      # ========= DATA TO SEND ===========
      form_fields = { "userId" => "#{Time.now.to_i}" }
      # ==================================

      args.gtk.http_post "http://localhost:9001/testing",
                         form_fields,
                         ["Content-Type: application/x-www-form-urlencoded"]

      args.gtk.notify! "http_post"
    end

    # ============= HTTP_POST_BODY =============
    if (args.inputs.mouse.inside_rect? args.state.post_body_button)
      # =========== DATA TO SEND ==============
      json = "{ \"userId\": \"#{Time.now.to_i}\"}"
      # ==================================

      args.gtk.http_post_body "http://localhost:9001/testing",
                              json,
                              ["Content-Type: application/json", "Content-Length: #{json.length}"]

      args.gtk.notify! "http_post_body"
    end
  end

  # calc
  args.inputs.http_requests.each do |r|
    puts "#{r}"
    if r.uri == "/testing"
      puts r
      args.state.request_to_s = "#{r}"
      args.state.request_body = r.raw_body
      r.respond 200, "ok"
    end
  end
end

def draw_label args, row, col, header, text
  label_pos = args.layout.rect(row: row, col: col, w: 0, h: 0)
  args.outputs.labels << "#{header}\n\n#{text}".wrapped_lines(80).map_with_index do |l, i|
    { x: label_pos.x, y: label_pos.y - (i * 15), text: l, size_enum: -2 }
  end
end

    C Extensions link

    Basics - main.rb link

    # ./samples/12_c_extensions/01_basics/app/main.rb
$gtk.ffi_misc.gtk_dlopen("ext")
include FFI::CExt

def tick args
  args.outputs.labels  << [640, 500, "mouse.x = #{args.mouse.x.to_i}", 5, 1]
  args.outputs.labels  << [640, 460, "square(mouse.x) = #{square(args.mouse.x.to_i)}", 5, 1]
  args.outputs.labels  << [640, 420, "mouse.y = #{args.mouse.y.to_i}", 5, 1]
  args.outputs.labels  << [640, 380, "square(mouse.y) = #{square(args.mouse.y.to_i)}", 5, 1]
end

    Intermediate - main.rb link

    # ./samples/12_c_extensions/02_intermediate/app/main.rb
$gtk.ffi_misc.gtk_dlopen("ext")
include FFI::RE

def split_words(input)
  words = []
  last = IntPointer.new
  re = re_compile("\\w+")
  first = re_matchp(re, input, last)
  while first != -1
    words << input.slice(first, last.value)
    input = input.slice(last.value + first, input.length)
    first = re_matchp(re, input, last)
  end
  words
end

def tick args
  args.outputs.labels  << [640, 500, split_words("hello, dragonriders!").join(' '), 5, 1]
end

    Native Pixel Arrays - main.rb link

    # ./samples/12_c_extensions/03_native_pixel_arrays/app/main.rb
$gtk.ffi_misc.gtk_dlopen("ext")
include FFI::CExt

def tick args
  args.state.rotation ||= 0

  update_scanner_texture   # this calls into a C extension!

  # New/changed pixel arrays get uploaded to the GPU before we render
  #  anything. At that point, they can be scaled, rotated, and otherwise
  #  used like any other sprite.
  w = 100
  h = 100
  x = (1280 - w) / 2
  y = (720 - h) / 2
  args.outputs.background_color = [64, 0, 128]
  args.outputs.primitives << [x, y, w, h, :scanner, args.state.rotation].sprite
  args.state.rotation += 1

  args.outputs.primitives << args.gtk.current_framerate_primitives
end

    Handcrafted Extension - main.rb link

    # ./samples/12_c_extensions/04_handcrafted_extension/app/main.rb
$gtk.ffi_misc.gtk_dlopen("ext")
include FFI::CExt

puts Adder.new.add_all(1, 2, 3, [4, 5, 6.0])

def tick args
end

    Handcrafted Extension - license.txt link

    # ./samples/12_c_extensions/04_handcrafted_extension/license.txt
Copyright 2022 DragonRuby LLC

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Handcrafted Extension Advanced - main.rb link

    # ./samples/12_c_extensions/04_handcrafted_extension_advanced/app/main.rb
def build_c_extension
  v = Time.now.to_i
  $gtk.exec("cd ./mygame && (env SUFFIX=#{v} sh ./pre.sh 2>&1 | tee ./build-results.txt)")
  build_output = $gtk.read_file("build-results.txt")
  {
    dll_name: "ext_#{v}",
    build_output: build_output
  }
end

def tick args
  # sets console command when sample app initially opens
  if Kernel.global_tick_count == 0
    results = build_c_extension
    dll = results.dll_name
    $gtk.dlopen(dll)
    puts ""
    puts ""
    puts "========================================================="
    puts "* INFO: Static Sprites, Classes, Draw Override"
    puts "* INFO: Please specify the number of sprites to render."
    args.gtk.console.set_command "reset_with count: 100"
  end

  args.state.star_count ||= 0

  # init
  if args.state.tick_count == 0
    args.state.stars = args.state.star_count.map { |i| Star.new }
    args.outputs.static_sprites << args.state.stars
  end

  # render framerate
  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.gtk.current_framerate_primitives
end

# resets game, and assigns star count given by user
def reset_with count: count
  $gtk.reset
  $gtk.args.state.star_count = count
end

$gtk.reset

    Handcrafted Extension Advanced - license.txt link

    # ./samples/12_c_extensions/04_handcrafted_extension_advanced/license.txt
Copyright 2022 DragonRuby LLC

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Handcrafted Extension Advanced - Metadata - cvars.txt link

    # ./samples/12_c_extensions/04_handcrafted_extension_advanced/metadata/cvars.txt
log.filter_subsystems=HTTPServer

# Whether or not the game should use the whole display, be sure to
# expose $gtk.set_window_fullscreen(false) or $gtk.request_quit
# to the player so they can get out of full screen mode.
# renderer.fullscreen=true

# Milliseconds to sleep per frame when in the background (zero to disable)
# renderer.background_sleep=0

# Set the window as borderless.
# Note: the ability to quit the application via OS shortcuts will not
# work if this value is true and you must provide a means to exit the
# game and wire it up to $gtk.request_quit
# renderer.borderless=true

    Ios main.rb link

    # ./samples/12_c_extensions/05_ios_c_extensions/app/main.rb
# NOTE: This is assumed to be executed with mygame as the root directory
#       you'll need to copy this code over there to try it out.

# Steps:
# 1. Create ext.h and ext.m
# 2. Create Info.plist file
# 3. Add before_create_payload to IOSWizard (which does the following):
#    a. run ./dragonruby-bind against C Extension and update implementation file
#    b. create output location for iOS Framework
#    c. compile C extension into Framework
#    d. copy framework to Payload directory and Sign
# 4. Run $wizards.ios.start env: (:prod|:dev|:hotload) to create ipa
# 5. Invoke args.gtk.dlopen giving the name of the C Extensions (~1s to load).
# 6. Invoke methods as needed.

# ===================================================
# before_create_payload iOS Wizard
# ===================================================
class IOSWizard < Wizard
  def before_create_payload
    puts "* INFO - before_create_payload"

    # invoke ./dragonruby-bind
    sh "./dragonruby-bind --output=mygame/ext-bind.m mygame/ext.h"

    # update generated implementation file
    contents = $gtk.read_file "ext-bind.m"
    contents = contents.gsub("#include \"mygame/ext.h\"", "#include \"mygame/ext.h\"\n#include \"mygame/ext.m\"")
    puts contents

    $gtk.write_file "ext-bind.m", contents

    # create output location
    sh "rm -rf ./mygame/native/ios-device/ext.framework"
    sh "mkdir -p ./mygame/native/ios-device/ext.framework"

    # compile C extension into framework
    sh <<-S
clang -I. -I./mruby/include -I./include -o "./mygame/native/ios-device/ext.framework/ext" \\
      -arch arm64 -dynamiclib -isysroot "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk" \\
      -install_name @rpath/ext.framework/ext \\
      -fembed-bitcode -Xlinker -rpath -Xlinker @loader_path/Frameworks -dead_strip -Xlinker -rpath -fobjc-arc -fobjc-link-runtime \\
      -F/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/System/Library/Frameworks \\
      -miphoneos-version-min=10.3 -Wl,-no_pie -licucore -stdlib=libc++ \\
      -framework CFNetwork -framework UIKit -framework Foundation \\
      ./mygame/ext-bind.m
S

    # stage extension
    sh "cp ./mygame/native/ios-device/Info.plist ./mygame/native/ios-device/ext.framework/Info.plist"
    sh "mkdir -p \"#{app_path}/Frameworks/ext.framework/\""
    sh "cp -r \"#{root_folder}/native/ios-device/ext.framework/\" \"#{app_path}/Frameworks/ext.framework/\""

    # sign
    sh <<-S
CODESIGN_ALLOCATE=#{codesign_allocate_path} #{codesign_path} \\
                                            -f -s \"#{certificate_name}\" \\
                                            \"#{app_path}/Frameworks/ext.framework/ext\"
S
  end
end

def tick args
  if args.state.tick_count == 60 && args.gtk.platform?(:ios)
    args.gtk.dlopen 'ext'
    include FFI::CExt
    puts "the results of hello world are:"
    puts hello_world()
    $gtk.console.show
  end
end

    Ios Metadata - cvars.txt link

    # ./samples/12_c_extensions/05_ios_c_extensions/metadata/cvars.txt

    Ios Metadata - ios_metadata.txt link

    # ./samples/12_c_extensions/05_ios_c_extensions/metadata/ios_metadata.txt
teamid=TEAMID
appid=APPID
appname=ICON NAME
version=1.0
devcert=NAME OF DEV CERT
prodcert=NAME OF PROD CERT

    Path Finding Algorithms link

    Breadth First Search - main.rb link

    # ./samples/13_path_finding_algorithms/01_breadth_first_search/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# A visual demonstration of a breadth first search
# Inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html

# An animation that can respond to user input in real time

# A breadth first search expands in all directions one step at a time
# The frontier is a queue of cells to be expanded from
# The visited hash allows quick lookups of cells that have been expanded from
# The walls hash allows quick lookup of whether a cell is a wall

# The breadth first search starts by adding the red star to the frontier array
# and marking it as visited
# Each step a cell is removed from the front of the frontier array (queue)
# Unless the neighbor is a wall or visited, it is added to the frontier array
# The neighbor is then marked as visited

# The frontier is blue
# Visited cells are light brown
# Walls are camo green
# Even when walls are visited, they will maintain their wall color

# The star can be moved by clicking and dragging
# Walls can be added and removed by clicking and dragging

class BreadthFirstSearch
  attr_gtk

  def initialize(args)
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    args.state.grid.width     = 30
    args.state.grid.height    = 15
    args.state.grid.cell_size = 40

    # Stores which step of the animation is being rendered
    # When the user moves the star or messes with the walls,
    # the breadth first search is recalculated up to this step
    args.state.anim_steps = 0

    # At some step the animation will end,
    # and further steps won't change anything (the whole grid will be explored)
    # This step is roughly the grid's width * height
    # When anim_steps equals max_steps no more calculations will occur
    # and the slider will be at the end
    args.state.max_steps  = args.state.grid.width * args.state.grid.height

    # Whether the animation should play or not
    # If true, every tick moves anim_steps forward one
    # Pressing the stepwise animation buttons will pause the animation
    args.state.play       = true

    # The location of the star and walls of the grid
    # They can be modified to have a different initial grid
    # Walls are stored in a hash for quick look up when doing the search
    args.state.star       = [0, 0]
    args.state.walls      = {
      [3, 3] => true,
      [3, 4] => true,
      [3, 5] => true,
      [3, 6] => true,
      [3, 7] => true,
      [3, 8] => true,
      [3, 9] => true,
      [3, 10] => true,
      [3, 11] => true,
      [4, 3] => true,
      [4, 4] => true,
      [4, 5] => true,
      [4, 6] => true,
      [4, 7] => true,
      [4, 8] => true,
      [4, 9] => true,
      [4, 10] => true,
      [4, 11] => true,

      [13, 0] => true,
      [13, 1] => true,
      [13, 2] => true,
      [13, 3] => true,
      [13, 4] => true,
      [13, 5] => true,
      [13, 6] => true,
      [13, 7] => true,
      [13, 8] => true,
      [13, 9] => true,
      [13, 10] => true,
      [14, 0] => true,
      [14, 1] => true,
      [14, 2] => true,
      [14, 3] => true,
      [14, 4] => true,
      [14, 5] => true,
      [14, 6] => true,
      [14, 7] => true,
      [14, 8] => true,
      [14, 9] => true,
      [14, 10] => true,

      [21, 8] => true,
      [21, 9] => true,
      [21, 10] => true,
      [21, 11] => true,
      [21, 12] => true,
      [21, 13] => true,
      [21, 14] => true,
      [22, 8] => true,
      [22, 9] => true,
      [22, 10] => true,
      [22, 11] => true,
      [22, 12] => true,
      [22, 13] => true,
      [22, 14] => true,
      [23, 8] => true,
      [23, 9] => true,
      [24, 8] => true,
      [24, 9] => true,
      [25, 8] => true,
      [25, 9] => true,
    }

    # Variables that are used by the breadth first search
    # Storing cells that the search has visited, prevents unnecessary steps
    # Expanding the frontier of the search in order makes the search expand
    # from the center outward
    args.state.visited    = {}
    args.state.frontier   = []


    # What the user is currently editing on the grid
    # Possible values are: :none, :slider, :star, :remove_wall, :add_wall

    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    args.state.click_and_drag = :none

    # Store the rects of the buttons that control the animation
    # They are here for user customization
    # Editing these might require recentering the text inside them
    # Those values can be found in the render_button methods

    args.state.buttons.left   = { x: 450, y: 600, w: 50,  h: 50 }
    args.state.buttons.center = { x: 500, y: 600, w: 200, h: 50 }
    args.state.buttons.right  = { x: 700, y: 600, w: 50,  h: 50 }

    # The variables below are related to the slider
    # They allow the user to customize them
    # They also give a central location for the render and input methods to get
    # information from
    # x & y are the coordinates of the leftmost part of the slider line
    args.state.slider.x = 400
    args.state.slider.y = 675
    # This is the width of the line
    args.state.slider.w = 360
    # This is the offset for the circle
    # Allows the center of the circle to be on the line,
    # as opposed to the upper right corner
    args.state.slider.offset = 20
    # This is the spacing between each of the notches on the slider
    # Notches are places where the circle can rest on the slider line
    # There needs to be a notch for each step before the maximum number of steps
    args.state.slider.spacing = args.state.slider.w.to_f / args.state.max_steps.to_f
  end

  # This method is called every frame/tick
  # Every tick, the current state of the search is rendered on the screen,
  # User input is processed, and
  # The next step in the search is calculated
  def tick
    render
    input
    # If animation is playing, and max steps have not been reached
    # Move the search a step forward
    if state.play && state.anim_steps < state.max_steps
      # Variable that tells the program what step to recalculate up to
      state.anim_steps += 1
      calc
    end
  end

  # Draws everything onto the screen
  def render
    render_buttons
    render_slider

    render_background
    render_visited
    render_frontier
    render_walls
    render_star
  end

  # The methods below subdivide the task of drawing everything to the screen

  # Draws the buttons that control the animation step and state
  def render_buttons
    render_left_button
    render_center_button
    render_right_button
  end

  # Draws the button which steps the search backward
  # Shows the user where to click to move the search backward
  def render_left_button
    # Draws the gray button, and a black border
    # The border separates the buttons visually
    outputs.solids  << buttons.left.merge(gray)
    outputs.borders << buttons.left

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    # If the button size is changed, the label might need to be edited as well
    # to keep the label in the center of the button
    label_x = buttons.left[:x] + 20
    label_y = buttons.left[:y] + 35
    outputs.labels << { x: label_x, y: label_y, text: '<' }
  end

  def render_center_button
    # Draws the gray button, and a black border
    # The border separates the buttons visually
    outputs.solids  << buttons.center.merge(gray)
    outputs.borders << buttons.center

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    # If the button size is changed, the label might need to be edited as well
    # to keep the label in the center of the button
    label_x = buttons.center[:x] + 37
    label_y = buttons.center[:y] + 35
    label_text = state.play ? "Pause Animation" : "Play Animation"
    outputs.labels << { x: label_x, y: label_y, text: label_text }
  end

  def render_right_button
    # Draws the gray button, and a black border
    # The border separates the buttons visually
    outputs.solids  << buttons.right.merge(gray)
    outputs.borders << buttons.right

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    label_x = buttons.right[:x] + 20
    label_y = buttons.right[:y] + 35
    outputs.labels << { x: label_x, y: label_y, text: ">" }
  end

  # Draws the slider so the user can move it and see the progress of the search
  def render_slider
    # Using a solid instead of a line, hides the line under the circle of the slider
    # Draws the line
    outputs.solids << {
      x: slider.x,
      y: slider.y,
      w: slider.w,
      h: 2
    }
    # The circle needs to be offset so that the center of the circle
    # overlaps the line instead of the upper right corner of the circle
    # The circle's x value is also moved based on the current seach step
    circle_x = (slider.x - slider.offset) + (state.anim_steps * slider.spacing)
    circle_y = (slider.y - slider.offset)
    outputs.sprites << {
      x: circle_x,
      y: circle_y,
      w: 37,
      h: 37,
      path: 'circle-white.png'
    }
  end

  # Draws what the grid looks like with nothing on it
  def render_background
    render_unvisited
    render_grid_lines
  end

  # Draws a rectangle the size of the entire grid to represent unvisited cells
  def render_unvisited
    rect = { x: 0, y: 0, w: grid.width, h: grid.height }
    rect = rect.transform_values { |v| v * grid.cell_size }
    outputs.solids << rect.merge(unvisited_color)
  end

  # Draws grid lines to show the division of the grid into cells
  def render_grid_lines
    outputs.lines << (0..grid.width).map { |x| vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| horizontal_line(y) }
  end

  # Easy way to draw vertical lines given an index
  def vertical_line x
    line = { x: x, y: 0, w: 0, h: grid.height }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Easy way to draw horizontal lines given an index
  def horizontal_line y
    line = { x: 0, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Draws the area that is going to be searched from
  # The frontier is the most outward parts of the search
  def render_frontier
    outputs.solids << state.frontier.map do |cell|
      render_cell cell, frontier_color
    end
  end

  # Draws the walls
  def render_walls
    outputs.solids << state.walls.map do |wall|
      render_cell wall, wall_color
    end
  end

  # Renders cells that have been searched in the appropriate color
  def render_visited
    outputs.solids << state.visited.map do |cell|
      render_cell cell, visited_color
    end
  end

  # Renders the star
  def render_star
    outputs.sprites << render_cell(state.star, { path: 'star.png' })
  end

  def render_cell cell, attrs
    {
      x: cell.x * grid.cell_size,
      y: cell.y * grid.cell_size,
      w: grid.cell_size,
      h: grid.cell_size
    }.merge attrs
  end

  # In code, the cells are represented as 1x1 rectangles
  # When drawn, the cells are larger than 1x1 rectangles
  # This method is used to scale up cells, and lines
  # Objects are scaled up according to the grid.cell_size variable
  # This allows for easy customization of the visual scale of the grid
  def scale_up(cell)
    # Prevents the original value of cell from being edited
    cell = cell.clone

    # If cell is just an x and y coordinate
    if cell.size == 2
      # Add a width and height of 1
      cell << 1
      cell << 1
    end

    # Scale all the values up
    cell.map! { |value| value * grid.cell_size }

    # Returns the scaled up cell
    cell
  end

  # This method processes user input every tick
  # This method allows the user to use the buttons, slider, and edit the grid
  # There are 2 types of input:
  #   Button Input
  #   Click and Drag Input
  #
  #   Button Input is used for the backward step and forward step buttons
  #   Input is detected by mouse up within the bounds of the rect
  #
  #   Click and Drag Input is used for moving the star, adding walls,
  #   removing walls, and the slider
  #
  #   When the mouse is down on the star, the click_and_drag variable is set to :star
  #   While click_and_drag equals :star, the cursor's position is used to calculate the
  #   appropriate drag behavior
  #
  #   When the mouse goes up click_and_drag is set to :none
  #
  #   A variable has to be used because the star has to continue being edited even
  #   when the cursor is no longer over the star
  #
  #   Similar things occur for the other Click and Drag inputs
  def input
    # Checks whether any of the buttons are being clicked
    input_buttons

    # The detection and processing of click and drag inputs are separate
    # The program has to remember that the user is dragging an object
    # even when the mouse is no longer over that object
    detect_click_and_drag
    process_click_and_drag
  end

  # Detects and Process input for each button
  def input_buttons
    input_left_button
    input_center_button
    input_next_step_button
  end

  # Checks if the previous step button is clicked
  # If it is, it pauses the animation and moves the search one step backward
  def input_left_button
    if left_button_clicked?
      state.play = false
      state.anim_steps -= 1
      recalculate
    end
  end

  # Controls the play/pause button
  # Inverses whether the animation is playing or not when clicked
  def input_center_button
    if center_button_clicked? or inputs.keyboard.key_down.space
      state.play = !state.play
    end
  end

  # Checks if the next step button is clicked
  # If it is, it pauses the animation and moves the search one step forward
  def input_next_step_button
    if right_button_clicked?
      state.play = false
      state.anim_steps += 1
      calc
    end
  end

  # Determines what the user is editing and stores the value
  # Storing the value allows the user to continue the same edit as long as the
  # mouse left click is held
  def detect_click_and_drag
    if inputs.mouse.up
      state.click_and_drag = :none
    elsif star_clicked?
      state.click_and_drag = :star
    elsif wall_clicked?
      state.click_and_drag = :remove_wall
    elsif grid_clicked?
      state.click_and_drag = :add_wall
    elsif slider_clicked?
      state.click_and_drag = :slider
    end
  end

  # Processes click and drag based on what the user is currently dragging
  def process_click_and_drag
    if state.click_and_drag == :star
      input_star
    elsif state.click_and_drag == :remove_wall
      input_remove_wall
    elsif state.click_and_drag == :add_wall
      input_add_wall
    elsif state.click_and_drag == :slider
      input_slider
    end
  end

  # Moves the star to the grid closest to the mouse
  # Only recalculates the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def input_star
    old_star = state.star.clone
    state.star = cell_closest_to_mouse
    unless old_star == state.star
      recalculate
    end
  end

  # Removes walls that are under the cursor
  def input_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if mouse_inside_grid?
      if state.walls.key?(cell_closest_to_mouse)
        state.walls.delete(cell_closest_to_mouse)
        recalculate
      end
    end
  end

  # Adds walls at cells under the cursor
  def input_add_wall
    if mouse_inside_grid?
      unless state.walls.key?(cell_closest_to_mouse)
        state.walls[cell_closest_to_mouse] = true
        recalculate
      end
    end
  end

  # This method is called when the user is editing the slider
  # It pauses the animation and moves the white circle to the closest integer point
  # on the slider
  # Changes the step of the search to be animated
  def input_slider
    state.play = false
    mouse_x = inputs.mouse.point.x

    # Bounds the mouse_x to the closest x value on the slider line
    mouse_x = slider.x if mouse_x < slider.x
    mouse_x = slider.x + slider.w if mouse_x > slider.x + slider.w

    # Sets the current search step to the one represented by the mouse x value
    # The slider's circle moves due to the render_slider method using anim_steps
    state.anim_steps = ((mouse_x - slider.x) / slider.spacing).to_i

    recalculate
  end

  # Whenever the user edits the grid,
  # The search has to be recalculated upto the current step
  # with the current grid as the initial state of the grid
  def recalculate
    # Resets the search
    state.frontier = []
    state.visited = {}

    # Moves the animation forward one step at a time
    state.anim_steps.times { calc }
  end


  # This method moves the search forward one step
  # When the animation is playing it is called every tick
  # And called whenever the current step of the animation needs to be recalculated

  # Moves the search forward one step
  # Parameter called_from_tick is true if it is called from the tick method
  # It is false when the search is being recalculated after user editing the grid
  def calc

    # The setup to the search
    # Runs once when the there is no frontier or visited cells
    if state.frontier.empty? && state.visited.empty?
      state.frontier << state.star
      state.visited[state.star] = true
    end

    # A step in the search
    unless state.frontier.empty?
      # Takes the next frontier cell
      new_frontier = state.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless state.visited.key?(neighbor) || state.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          state.frontier << neighbor
          state.visited[neighbor] = true
        end
      end
    end
  end


  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors(cell)
    neighbors = []

    neighbors << [cell.x, cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y] unless cell.x == grid.width - 1
    neighbors << [cell.x, cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y] unless cell.x == 0

    neighbors
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse helps with this
  def cell_closest_to_mouse
    # Closest cell to the mouse
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Bound x and y to the grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # These methods detect when the buttons are clicked
  def left_button_clicked?
    inputs.mouse.up && inputs.mouse.point.inside_rect?(buttons.left)
  end

  def center_button_clicked?
    inputs.mouse.up && inputs.mouse.point.inside_rect?(buttons.center)
  end

  def right_button_clicked?
    inputs.mouse.up && inputs.mouse.point.inside_rect?(buttons.right)
  end

  # Signal that the user is going to be moving the slider
  # Is the mouse down on the circle of the slider?
  def slider_clicked?
    circle_x = (slider.x - slider.offset) + (state.anim_steps * slider.spacing)
    circle_y = (slider.y - slider.offset)
    circle_rect = [circle_x, circle_y, 37, 37]
    inputs.mouse.down && inputs.mouse.point.inside_rect?(circle_rect)
  end

  # Signal that the user is going to be moving the star
  def star_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(scale_up(state.star))
  end

  # Signal that the user is going to be removing walls
  def wall_clicked?
    inputs.mouse.down && mouse_inside_a_wall?
  end

  # Signal that the user is going to be adding walls
  def grid_clicked?
    inputs.mouse.down && mouse_inside_grid?
  end

  # Returns whether the mouse is inside of a wall
  # Part of the condition that checks whether the user is removing a wall
  def mouse_inside_a_wall?
    state.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(scale_up([wall.x, wall.y]))
    end

    false
  end

  # Returns whether the mouse is inside of a grid
  # Part of the condition that checks whether the user is adding a wall
  def mouse_inside_grid?
    inputs.mouse.point.inside_rect?(scale_up([0, 0, grid.width, grid.height]))
  end

  # Light brown
  def unvisited_color
    { r: 221, g: 212, b: 213 }
  end

  # Dark Brown
  def visited_color
    { r: 204, g: 191, b: 179 }
  end

  # Blue
  def frontier_color
    { r: 103, g: 136, b: 204 }
  end

  # Camo Green
  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  # Button Background
  def gray
    { r: 190, g: 190, b: 190 }
  end

  # These methods make the code more concise
  def grid
    state.grid
  end

  def buttons
    state.buttons
  end

  def slider
    state.slider
  end
end

# Method that is called by DragonRuby periodically
# Used for updating animations and calculations
def tick args

  # Pressing r will reset the application
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  # Every tick, new args are passed, and the Breadth First Search tick is called
  $breadth_first_search ||= BreadthFirstSearch.new(args)
  $breadth_first_search.args = args
  $breadth_first_search.tick
end


def reset
  $breadth_first_search = nil
end

    Detailed Breadth First Search - main.rb link

    # ./samples/13_path_finding_algorithms/02_detailed_breadth_first_search/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# A visual demonstration of a breadth first search
# Inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html

# An animation that can respond to user input in real time

# A breadth first search expands in all directions one step at a time
# The frontier is a queue of cells to be expanded from
# The visited hash allows quick lookups of cells that have been expanded from
# The walls hash allows quick lookup of whether a cell is a wall

# The breadth first search starts by adding the red star to the frontier array
# and marking it as visited
# Each step a cell is removed from the front of the frontier array (queue)
# Unless the neighbor is a wall or visited, it is added to the frontier array
# The neighbor is then marked as visited

# The frontier is blue
# Visited cells are light brown
# Walls are camo green
# Even when walls are visited, they will maintain their wall color

# This search numbers the order in which new cells are explored
# The next cell from where the search will continue is highlighted yellow
# And the cells that will be considered for expansion are in semi-transparent green

# The star can be moved by clicking and dragging
# Walls can be added and removed by clicking and dragging

class DetailedBreadthFirstSearch
  attr_gtk

  def initialize(args)
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    args.state.grid.width     = 9
    args.state.grid.height    = 4
    args.state.grid.cell_size = 90

    # Stores which step of the animation is being rendered
    # When the user moves the star or messes with the walls,
    # the breadth first search is recalculated up to this step
    args.state.anim_steps = 0

    # At some step the animation will end,
    # and further steps won't change anything (the whole grid will be explored)
    # This step is roughly the grid's width * height
    # When anim_steps equals max_steps no more calculations will occur
    # and the slider will be at the end
    args.state.max_steps  = args.state.grid.width * args.state.grid.height

    # The location of the star and walls of the grid
    # They can be modified to have a different initial grid
    # Walls are stored in a hash for quick look up when doing the search
    args.state.star       = [3, 2]
    args.state.walls      = {}

    # Variables that are used by the breadth first search
    # Storing cells that the search has visited, prevents unnecessary steps
    # Expanding the frontier of the search in order makes the search expand
    # from the center outward
    args.state.visited    = {}
    args.state.frontier   = []
    args.state.cell_numbers = []



    # What the user is currently editing on the grid
    # Possible values are: :none, :slider, :star, :remove_wall, :add_wall

    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    args.state.click_and_drag = :none

    # The x, y, w, h values for the buttons
    # Allow easy movement of the buttons location
    # A centralized location to get values to detect input and draw the buttons
    # Editing these values might mean needing to edit the label offsets
    # which can be found in the appropriate render button methods
    args.state.buttons.left  = [450, 600, 160, 50]
    args.state.buttons.right = [610, 600, 160, 50]

    # The variables below are related to the slider
    # They allow the user to customize them
    # They also give a central location for the render and input methods to get
    # information from
    # x & y are the coordinates of the leftmost part of the slider line
    args.state.slider.x = 400
    args.state.slider.y = 675
    # This is the width of the line
    args.state.slider.w = 360
    # This is the offset for the circle
    # Allows the center of the circle to be on the line,
    # as opposed to the upper right corner
    args.state.slider.offset = 20
    # This is the spacing between each of the notches on the slider
    # Notches are places where the circle can rest on the slider line
    # There needs to be a notch for each step before the maximum number of steps
    args.state.slider.spacing = args.state.slider.w.to_f / args.state.max_steps.to_f
  end

  # This method is called every frame/tick
  # Every tick, the current state of the search is rendered on the screen,
  # User input is processed, and
  def tick
    render
    input
  end

  # This method is called from tick and renders everything every tick
  def render
    render_buttons
    render_slider

    render_background
    render_visited
    render_frontier
    render_walls
    render_star

    render_highlights
    render_cell_numbers
  end

  # The methods below subdivide the task of drawing everything to the screen

  # Draws the buttons that move the search backward or forward
  # These buttons are rendered so the user knows where to click to move the search
  def render_buttons
    render_left_button
    render_right_button
  end

  # Renders the button which steps the search backward
  # Shows the user where to click to move the search backward
  def render_left_button
    # Draws the gray button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.left, gray]
    outputs.borders << [buttons.left]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    label_x = buttons.left.x + 05
    label_y = buttons.left.y + 35
    outputs.labels  << [label_x, label_y, "< Step backward"]
  end

  # Renders the button which steps the search forward
  # Shows the user where to click to move the search forward
  def render_right_button
    # Draws the gray button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.right, gray]
    outputs.borders << [buttons.right]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    label_x = buttons.right.x + 10
    label_y = buttons.right.y + 35
    outputs.labels  << [label_x, label_y, "Step forward >"]
  end

  # Draws the slider so the user can move it and see the progress of the search
  def render_slider
    # Using primitives hides the line under the white circle of the slider
    # Draws the line
    outputs.primitives << [slider.x, slider.y, slider.x + slider.w, slider.y].line
    # The circle needs to be offset so that the center of the circle
    # overlaps the line instead of the upper right corner of the circle
    # The circle's x value is also moved based on the current seach step
    circle_x = (slider.x - slider.offset) + (state.anim_steps * slider.spacing)
    circle_y = (slider.y - slider.offset)
    circle_rect = [circle_x, circle_y, 37, 37]
    outputs.primitives << [circle_rect, 'circle-white.png'].sprite
  end

  # Draws what the grid looks like with nothing on it
  # Which is a bunch of unvisited cells
  # Drawn first so other things can draw on top of it
  def render_background
    render_unvisited

    # The grid lines make the cells appear separate
    render_grid_lines
  end

  # Draws a rectangle the size of the entire grid to represent unvisited cells
  # Unvisited cells are the default cell
  def render_unvisited
    background = [0, 0, grid.width, grid.height]
    outputs.solids << scale_up(background).merge(unvisited_color)
  end

  # Draws grid lines to show the division of the grid into cells
  def render_grid_lines
    outputs.lines << (0..grid.width).map do |x|
      scale_up(vertical_line(x)).merge(grid_line_color)
    end
    outputs.lines << (0..grid.height).map do |y|
      scale_up(horizontal_line(y)).merge(grid_line_color)
    end
  end

  # Easy way to get a vertical line given an index
  def vertical_line column
    [column, 0, 0, grid.height]
  end

  # Easy way to get a horizontal line given an index
  def horizontal_line row
    [0, row, grid.width, 0]
  end

  # Draws the area that is going to be searched from
  # The frontier is the most outward parts of the search
  def render_frontier
    state.frontier.each do |cell|
      outputs.solids << scale_up(cell).merge(frontier_color)
    end
  end

  # Draws the walls
  def render_walls
    state.walls.each_key do |wall|
      outputs.solids << scale_up(wall).merge(wall_color)
    end
  end

  # Renders cells that have been searched in the appropriate color
  def render_visited
    state.visited.each_key do |cell|
      outputs.solids << scale_up(cell).merge(visited_color)
    end
  end

  # Renders the star
  def render_star
    outputs.sprites << scale_up(state.star).merge({ path: 'star.png' })
  end

  # Cells have a number rendered in them based on when they were explored
  # This is based off of their index in the cell_numbers array
  # Cells are added to this array the same time they are added to the frontier array
  def render_cell_numbers
    state.cell_numbers.each_with_index do |cell, index|
      # Math that approx centers the number in the cell
      label_x = (cell.x * grid.cell_size) + grid.cell_size / 2 - 5
      label_y = (cell.y * grid.cell_size) + (grid.cell_size / 2) + 5

      outputs.labels << [label_x, label_y, (index + 1).to_s]
    end
  end

  # The next frontier to be expanded is highlighted yellow
  # Its adjacent non-wall neighbors have their border highlighted green
  # This is to show the user how the search expands
  def render_highlights
    return if state.frontier.empty?

    # Highlight the next frontier to be expanded yellow
    next_frontier = state.frontier[0]
    outputs.solids << scale_up(next_frontier).merge(highlighter_yellow)

    # Neighbors have a semi-transparent green layer over them
    # Unless the neighbor is a wall
    adjacent_neighbors(next_frontier).each do |neighbor|
      unless state.walls.key?(neighbor)
        outputs.solids << scale_up(neighbor).merge(highlighter_green)
      end
    end
  end


  # Cell Size is used when rendering to allow the grid to be scaled up or down
  # Cells in the frontier array and visited hash and walls hash are stored as x & y
  # Scaling up cells and lines when rendering allows omitting of width and height
  def scale_up(cell)
    if cell.size == 2
      return {
        x: cell.x * grid.cell_size,
        y: cell.y * grid.cell_size,
        w: grid.cell_size,
        h: grid.cell_size
      }
    else
      return {
        x: cell.x * grid.cell_size,
        y: cell.y * grid.cell_size,
        w: cell.w * grid.cell_size,
        h: cell.h * grid.cell_size
      }
    end
  end


  # This method processes user input every tick
  # This method allows the user to use the buttons, slider, and edit the grid
  # There are 2 types of input:
  #   Button Input
  #   Click and Drag Input
  #
  #   Button Input is used for the backward step and forward step buttons
  #   Input is detected by mouse up within the bounds of the rect
  #
  #   Click and Drag Input is used for moving the star, adding walls,
  #   removing walls, and the slider
  #
  #   When the mouse is down on the star, the click_and_drag variable is set to :star
  #   While click_and_drag equals :star, the cursor's position is used to calculate the
  #   appropriate drag behavior
  #
  #   When the mouse goes up click_and_drag is set to :none
  #
  #   A variable has to be used because the star has to continue being edited even
  #   when the cursor is no longer over the star
  #
  #   Similar things occur for the other Click and Drag inputs
  def input
    # Processes inputs for the buttons
    input_buttons

    # Detects which if any click and drag input is occurring
    detect_click_and_drag

    # Does the appropriate click and drag input based on the click_and_drag variable
    process_click_and_drag
  end

  # Detects and Process input for each button
  def input_buttons
    input_left_button
    input_right_button
  end

  # Checks if the previous step button is clicked
  # If it is, it pauses the animation and moves the search one step backward
  def input_left_button
    if left_button_clicked?
      unless state.anim_steps == 0
        state.anim_steps -= 1
        recalculate
      end
    end
  end

  # Checks if the next step button is clicked
  # If it is, it pauses the animation and moves the search one step forward
  def input_right_button
    if right_button_clicked?
      unless state.anim_steps == state.max_steps
        state.anim_steps += 1
        # Although normally recalculate would be called here
        # because the right button only moves the search forward
        # We can just do that
        calc
      end
    end
  end

  # Whenever the user edits the grid,
  # The search has to be recalculated upto the current step

  def recalculate
    # Resets the search
    state.frontier = []
    state.visited = {}
    state.cell_numbers = []

    # Moves the animation forward one step at a time
    state.anim_steps.times { calc }
  end


  # Determines what the user is clicking and planning on dragging
  # Click and drag input is initiated by a click on the appropriate item
  # and ended by mouse up
  # Storing the value allows the user to continue the same edit as long as the
  # mouse left click is held
  def detect_click_and_drag
    if inputs.mouse.up
      state.click_and_drag = :none
    elsif star_clicked?
      state.click_and_drag = :star
    elsif wall_clicked?
      state.click_and_drag = :remove_wall
    elsif grid_clicked?
      state.click_and_drag = :add_wall
    elsif slider_clicked?
      state.click_and_drag = :slider
    end
  end

  # Processes input based on what the user is currently dragging
  def process_click_and_drag
    if state.click_and_drag == :slider
      input_slider
    elsif state.click_and_drag == :star
      input_star
    elsif state.click_and_drag == :remove_wall
      input_remove_wall
    elsif state.click_and_drag == :add_wall
      input_add_wall
    end
  end

  # This method is called when the user is dragging the slider
  # It moves the current animation step to the point represented by the slider
  def input_slider
    mouse_x = inputs.mouse.point.x

    # Bounds the mouse_x to the closest x value on the slider line
    mouse_x = slider.x if mouse_x < slider.x
    mouse_x = slider.x + slider.w if mouse_x > slider.x + slider.w

    # Sets the current search step to the one represented by the mouse x value
    # The slider's circle moves due to the render_slider method using anim_steps
    state.anim_steps = ((mouse_x - slider.x) / slider.spacing).to_i

    recalculate
  end

  # Moves the star to the grid closest to the mouse
  # Only recalculates the search if the star changes position
  # Called whenever the user is dragging the star
  def input_star
    old_star = state.star.clone
    state.star = cell_closest_to_mouse
    unless old_star == state.star
      recalculate
    end
  end

  # Removes walls that are under the cursor
  def input_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if mouse_inside_grid?
      if state.walls.key?(cell_closest_to_mouse)
        state.walls.delete(cell_closest_to_mouse)
        recalculate
      end
    end
  end

  # Adds walls at cells under the cursor
  def input_add_wall
    # Adds a wall to the hash
    # We can use the grid closest to mouse, because the cursor is inside the grid
    if mouse_inside_grid?
      unless state.walls.key?(cell_closest_to_mouse)
        state.walls[cell_closest_to_mouse] = true
        recalculate
      end
    end
  end

  # This method moves the search forward one step
  # When the animation is playing it is called every tick
  # And called whenever the current step of the animation needs to be recalculated

  # Moves the search forward one step
  # Parameter called_from_tick is true if it is called from the tick method
  # It is false when the search is being recalculated after user editing the grid
  def calc
    # The setup to the search
    # Runs once when the there is no frontier or visited cells
    if state.frontier.empty? && state.visited.empty?
      state.frontier << state.star
      state.visited[state.star] = true
    end

    # A step in the search
    unless state.frontier.empty?
      # Takes the next frontier cell
      new_frontier = state.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless state.visited.key?(neighbor) || state.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          state.frontier << neighbor
          state.visited[neighbor] = true

          # Also assign them a frontier number
          state.cell_numbers << neighbor
        end
      end
    end
  end


  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors cell
    neighbors = []

    neighbors << [cell.x, cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y] unless cell.x == grid.width - 1
    neighbors << [cell.x, cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y] unless cell.x == 0

    neighbors
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the grid closest to the mouse helps with this
  def cell_closest_to_mouse
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    [x, y]
  end


  # These methods detect when the buttons are clicked
  def left_button_clicked?
    (inputs.mouse.up && inputs.mouse.point.inside_rect?(buttons.left)) || inputs.keyboard.key_up.left
  end

  def right_button_clicked?
    (inputs.mouse.up && inputs.mouse.point.inside_rect?(buttons.right)) || inputs.keyboard.key_up.right
  end

  # Signal that the user is going to be moving the slider
  def slider_clicked?
    circle_x = (slider.x - slider.offset) + (state.anim_steps * slider.spacing)
    circle_y = (slider.y - slider.offset)
    circle_rect = [circle_x, circle_y, 37, 37]
    inputs.mouse.down && inputs.mouse.point.inside_rect?(circle_rect)
  end

  # Signal that the user is going to be moving the star
  def star_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(scale_up(state.star))
  end

  # Signal that the user is going to be removing walls
  def wall_clicked?
    inputs.mouse.down && mouse_inside_a_wall?
  end

  # Signal that the user is going to be adding walls
  def grid_clicked?
    inputs.mouse.down && mouse_inside_grid?
  end

  # Returns whether the mouse is inside of a wall
  # Part of the condition that checks whether the user is removing a wall
  def mouse_inside_a_wall?
    state.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(scale_up(wall))
    end

    false
  end

  # Returns whether the mouse is inside of a grid
  # Part of the condition that checks whether the user is adding a wall
  def mouse_inside_grid?
    inputs.mouse.point.inside_rect?(scale_up([0, 0, grid.width, grid.height]))
  end

  # These methods provide handy aliases to colors

  # Light brown
  def unvisited_color
    { r: 221, g: 212, b: 213 }
  end

  # Black
  def grid_line_color
    { r: 255, g: 255, b: 255 }
  end

  # Dark Brown
  def visited_color
    { r: 204, g: 191, b: 179 }
  end

  # Blue
  def frontier_color
    { r: 103, g: 136, b: 204 }
  end

  # Camo Green
  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  # Next frontier to be expanded
  def highlighter_yellow
    { r: 214, g: 231, b: 125 }
  end

  # The neighbors of the next frontier to be expanded
  def highlighter_green
    { r: 65, g: 191, b: 127, a: 70 }
  end

  # Button background
  def gray
    [190, 190, 190]
  end

  # These methods make the code more concise
  def grid
    state.grid
  end

  def buttons
    state.buttons
  end

  def slider
    state.slider
  end
end


def tick args
  # Pressing r resets the program
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  $detailed_breadth_first_search ||= DetailedBreadthFirstSearch.new(args)
  $detailed_breadth_first_search.args = args
  $detailed_breadth_first_search.tick
end


def reset
  $detailed_breadth_first_search = nil
end

    Breadcrumbs - main.rb link

    # ./samples/13_path_finding_algorithms/03_breadcrumbs/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# This program is inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html

class Breadcrumbs
  attr_gtk

  # This method is called every frame/tick
  # Every tick, the current state of the search is rendered on the screen,
  # User input is processed, and
  # The next step in the search is calculated
  def tick
    defaults
    # If the grid has not been searched
    if search.came_from.empty?
      calc
      # Calc Path
    end
    render
    input
  end

  def defaults
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    grid.width     ||= 30
    grid.height    ||= 15
    grid.cell_size ||= 40
    grid.rect      ||= [0, 0, grid.width, grid.height]

    # The location of the star and walls of the grid
    # They can be modified to have a different initial grid
    # Walls are stored in a hash for quick look up when doing the search
    grid.star   ||= [2, 8]
    grid.target ||= [10, 5]
    grid.walls  ||= {
      [3, 3] => true,
      [3, 4] => true,
      [3, 5] => true,
      [3, 6] => true,
      [3, 7] => true,
      [3, 8] => true,
      [3, 9] => true,
      [3, 10] => true,
      [3, 11] => true,
      [4, 3] => true,
      [4, 4] => true,
      [4, 5] => true,
      [4, 6] => true,
      [4, 7] => true,
      [4, 8] => true,
      [4, 9] => true,
      [4, 10] => true,
      [4, 11] => true,
      [13, 0] => true,
      [13, 1] => true,
      [13, 2] => true,
      [13, 3] => true,
      [13, 4] => true,
      [13, 5] => true,
      [13, 6] => true,
      [13, 7] => true,
      [13, 8] => true,
      [13, 9] => true,
      [13, 10] => true,
      [14, 0] => true,
      [14, 1] => true,
      [14, 2] => true,
      [14, 3] => true,
      [14, 4] => true,
      [14, 5] => true,
      [14, 6] => true,
      [14, 7] => true,
      [14, 8] => true,
      [14, 9] => true,
      [14, 10] => true,
      [21, 8] => true,
      [21, 9] => true,
      [21, 10] => true,
      [21, 11] => true,
      [21, 12] => true,
      [21, 13] => true,
      [21, 14] => true,
      [22, 8] => true,
      [22, 9] => true,
      [22, 10] => true,
      [22, 11] => true,
      [22, 12] => true,
      [22, 13] => true,
      [22, 14] => true,
      [23, 8] => true,
      [23, 9] => true,
      [24, 8] => true,
      [24, 9] => true,
      [25, 8] => true,
      [25, 9] => true,
    }

    # Variables that are used by the breadth first search
    # Storing cells that the search has visited, prevents unnecessary steps
    # Expanding the frontier of the search in order makes the search expand
    # from the center outward

    # The cells from which the search is to expand
    search.frontier              ||= []
    # A hash of where each cell was expanded from
    # The key is a cell, and the value is the cell it came from
    search.came_from             ||= {}
    # Cells that are part of the path from the target to the star
    search.path                  ||= {}

    # What the user is currently editing on the grid
    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    state.current_input ||= :none
  end

  def calc
    # Setup the search to start from the star
    search.frontier << grid.star
    search.came_from[grid.star] = nil

    # Until there are no more cells to expand from
    until search.frontier.empty?
      # Takes the next frontier cell
      new_frontier = search.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless search.came_from.has_key?(neighbor) || grid.walls.has_key?(neighbor)
          # Add them to the frontier and mark them as visited in the first grid
          # Unless the target has been visited
          # Add the neighbor to the frontier and remember which cell it came from
          search.frontier << neighbor
          search.came_from[neighbor] = new_frontier
        end
      end
    end
  end


  # Draws everything onto the screen
  def render
    render_background
    # render_heat_map
    render_walls
    # render_path
    # render_labels
    render_arrows
    render_star
    render_target
    unless grid.walls.has_key?(grid.target)
      render_trail
    end
  end

  def render_trail(current_cell=grid.target)
    return if current_cell == grid.star
    parent_cell = search.came_from[current_cell]
    if current_cell && parent_cell
      outputs.lines << [(current_cell.x + 0.5) * grid.cell_size, (current_cell.y + 0.5) * grid.cell_size,
      (parent_cell.x + 0.5) * grid.cell_size, (parent_cell.y + 0.5) * grid.cell_size, purple]

    end
    render_trail(parent_cell)
  end

  def render_arrows
    search.came_from.each do |child, parent|
      if parent && child
        arrow_cell = [(child.x + parent.x) / 2, (child.y + parent.y) / 2]
        if parent.x > child.x # If the parent cell is to the right of the child cell
          # Point arrow right
          outputs.sprites << scale_up(arrow_cell).merge({ path: 'arrow.png', angle: 0})
        elsif parent.x < child.x # If the parent cell is to the right of the child cell
          outputs.sprites << scale_up(arrow_cell).merge({ path: 'arrow.png', angle: 180})
        elsif parent.y > child.y # If the parent cell is to the right of the child cell
          outputs.sprites << scale_up(arrow_cell).merge({ path: 'arrow.png', angle: 90})
        elsif parent.y < child.y # If the parent cell is to the right of the child cell
          outputs.sprites << scale_up(arrow_cell).merge({ path: 'arrow.png', angle: 270})
        end
      end
    end
  end

  # The methods below subdivide the task of drawing everything to the screen

  # Draws what the grid looks like with nothing on it
  def render_background
    render_unvisited
    render_grid_lines
  end

  # Draws both grids
  def render_unvisited
    outputs.solids << scale_up(grid.rect).merge(unvisited_color)
  end

  # Draws grid lines to show the division of the grid into cells
  def render_grid_lines
    outputs.lines << (0..grid.width).map { |x| vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| horizontal_line(y) }
  end

  # Easy way to draw vertical lines given an index
  def vertical_line x
    line = { x: x, y: 0, w: 0, h: grid.height }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Easy way to draw horizontal lines given an index
  def horizontal_line y
    line = { x: 0, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Draws the walls on both grids
  def render_walls
    outputs.solids << grid.walls.map do |key, value|
      scale_up(key).merge(wall_color)
    end
  end

  # Renders the star on both grids
  def render_star
    outputs.sprites << scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the target on both grids
  def render_target
    outputs.sprites << scale_up(grid.target).merge({ path: 'target.png'})
  end

  # Labels the grids
  def render_labels
    outputs.labels << [200, 625, "Without early exit"]
  end

  # Renders the path based off of the search.path hash
  def render_path
    # If the star and target are disconnected there will only be one path
    # The path should not render in that case
    unless search.path.size == 1
      search.path.each_key do | cell |
        # Renders path on both grids
        outputs.solids << [scale_up(cell), path_color]
      end
    end
  end

  # Calculates the path from the target to the star after the search is over
  # Relies on the came_from hash
  # Fills the search.path hash, which is later rendered on screen
  def calc_path
    endpoint = grid.target
    while endpoint
      search.path[endpoint] = true
      endpoint = search.came_from[endpoint]
    end
  end

  # In code, the cells are represented as 1x1 rectangles
  # When drawn, the cells are larger than 1x1 rectangles
  # This method is used to scale up cells, and lines
  # Objects are scaled up according to the grid.cell_size variable
  # This allows for easy customization of the visual scale of the grid
  def scale_up(cell)
    x = cell.x * grid.cell_size
    y = cell.y * grid.cell_size
    w = cell.w.zero? ? grid.cell_size : cell.w * grid.cell_size
    h = cell.h.zero? ? grid.cell_size : cell.h * grid.cell_size
    { x: x, y: y, w: w, h: h }
  end

  # This method processes user input every tick
  # Any method with "1" is related to the first grid
  # Any method with "2" is related to the second grid
  def input
    # The program has to remember that the user is dragging an object
    # even when the mouse is no longer over that object
    # So detecting input and processing input is separate
    # detect_input
    # process_input
    if inputs.mouse.up
      state.current_input = :none
    elsif star_clicked?
      state.current_input = :star
    end

    if mouse_inside_grid?
      unless grid.target == cell_closest_to_mouse
        grid.target = cell_closest_to_mouse
      end
      if state.current_input == :star
        unless grid.star == cell_closest_to_mouse
          grid.star = cell_closest_to_mouse
        end
      end
    end
  end

  # Determines what the user is editing and stores the value
  # Storing the value allows the user to continue the same edit as long as the
  # mouse left click is held
  def detect_input
    # When the mouse is up, nothing is being edited
    if inputs.mouse.up
      state.current_input = :none
    # When the star in the no second grid is clicked
    elsif star_clicked?
      state.current_input = :star
    # When the target in the no second grid is clicked
    elsif target_clicked?
      state.current_input = :target
    # When a wall in the first grid is clicked
    elsif wall_clicked?
      state.current_input = :remove_wall
    # When the first grid is clicked
    elsif grid_clicked?
      state.current_input = :add_wall
    end
  end

  # Processes click and drag based on what the user is currently dragging
  def process_input
    if state.current_input == :star
      input_star
    elsif state.current_input == :target
      input_target
    elsif state.current_input == :remove_wall
      input_remove_wall
    elsif state.current_input == :add_wall
      input_add_wall
    end
  end

  # Moves the star to the cell closest to the mouse in the first grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def input_star
    old_star = grid.star.clone
    grid.star = cell_closest_to_mouse
    unless old_star == grid.star
      reset_search
    end
  end

  # Moves the target to the grid closest to the mouse in the first grid
  # Only reset_searchs the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def input_target
    old_target = grid.target.clone
    grid.target = cell_closest_to_mouse
    unless old_target == grid.target
      reset_search
    end
  end

  # Removes walls in the first grid that are under the cursor
  def input_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if mouse_inside_grid?
      if grid.walls.key?(cell_closest_to_mouse)
        grid.walls.delete(cell_closest_to_mouse)
        reset_search
      end
    end
  end

  # Adds a wall in the first grid in the cell the mouse is over
  def input_add_wall
    if mouse_inside_grid?
      unless grid.walls.key?(cell_closest_to_mouse)
        grid.walls[cell_closest_to_mouse] = true
        reset_search
      end
    end
  end


  # Whenever the user edits the grid,
  # The search has to be reset_searchd upto the current step
  # with the current grid as the initial state of the grid
  def reset_search
    # Reset_Searchs the search
    search.frontier  = []
    search.came_from = {}
    search.path      = {}
  end


  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors(cell)
    neighbors = []

    # Gets all the valid neighbors into the array
    # From southern neighbor, clockwise
    neighbors << [cell.x, cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y] unless cell.x == 0
    neighbors << [cell.x, cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y] unless cell.x == grid.width - 1

    # Sorts the neighbors so the rendered path is a zigzag path
    # Cells in a diagonal direction are given priority
    # Comment this line to see the difference
    neighbors = neighbors.sort_by { |neighbor_x, neighbor_y|  proximity_to_star(neighbor_x, neighbor_y) }

    neighbors
  end

  # Finds the vertical and horizontal distance of a cell from the star
  # and returns the larger value
  # This method is used to have a zigzag pattern in the rendered path
  # A cell that is [5, 5] from the star,
  # is explored before over a cell that is [0, 7] away.
  # So, if possible, the search tries to go diagonal (zigzag) first
  def proximity_to_star(x, y)
    distance_x = (grid.star.x - x).abs
    distance_y = (grid.star.y - y).abs

    if distance_x > distance_y
      return distance_x
    else
      return distance_y
    end
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse helps with this
  def cell_closest_to_mouse
    # Closest cell to the mouse in the first grid
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Bound x and y to the grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # Signal that the user is going to be moving the star from the first grid
  def star_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(scale_up(grid.star))
  end

  # Signal that the user is going to be moving the target from the first grid
  def target_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(scale_up(grid.target))
  end

  # Signal that the user is going to be adding walls from the first grid
  def grid_clicked?
    inputs.mouse.down && mouse_inside_grid?
  end

  # Returns whether the mouse is inside of the first grid
  # Part of the condition that checks whether the user is adding a wall
  def mouse_inside_grid?
    inputs.mouse.point.inside_rect?(scale_up(grid.rect))
  end

  # These methods provide handy aliases to colors

  # Light brown
  def unvisited_color
    { r: 221, g: 212, b: 213 }
  end

  # Camo Green
  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  # Pastel White
  def path_color
    [231, 230, 228]
  end

  def red
    [255, 0, 0]
  end

  def purple
    [149, 64, 191]
  end

  # Makes code more concise
  def grid
    state.grid
  end

  def search
    state.search
  end
end

# Method that is called by DragonRuby periodically
# Used for updating animations and calculations
def tick args

  # Pressing r will reset the application
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  # Every tick, new args are passed, and the Breadth First Search tick is called
  $breadcrumbs ||= Breadcrumbs.new
  $breadcrumbs.args = args
  $breadcrumbs.tick
end


def reset
  $breadcrumbs = nil
end

 #  # Representation of how far away visited cells are from the star
 #  # Replaces the render_visited method
 #  # Visually demonstrates the effectiveness of early exit for pathfinding
 #  def render_heat_map
 #    # THIS CODE NEEDS SOME FIXING DUE TO REFACTORING
 #    search.came_from.each_key do | cell |
 #      distance = (grid.star.x - visited_cell.x).abs + (state.star.y - visited_cell.y).abs
 #      max_distance = grid.width + grid.height
 #      alpha = 255.to_i * distance.to_i / max_distance.to_i
 #      outputs.solids << [scale_up(visited_cell), red, alpha]
 #      # outputs.solids << [early_exit_scale_up(visited_cell), red, alpha]
 #    end
 #  end

    Early Exit - main.rb link

    # ./samples/13_path_finding_algorithms/04_early_exit/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# Comparison of a breadth first search with and without early exit
# Inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html

# Demonstrates the exploration difference caused by early exit
# Also demonstrates how breadth first search is used for path generation

# The left grid is a breadth first search without early exit
# The right grid is a breadth first search with early exit
# The red squares represent how far the search expanded
# The darker the red, the farther the search proceeded
# Comparison of the heat map reveals how much searching can be saved by early exit
# The white path shows path generation via breadth first search
class EarlyExitBreadthFirstSearch
  attr_gtk

  # This method is called every frame/tick
  # Every tick, the current state of the search is rendered on the screen,
  # User input is processed, and
  # The next step in the search is calculated
  def tick
    defaults
    # If the grid has not been searched
    if state.visited.empty?
      # Complete the search
      state.max_steps.times { step }
      # And calculate the path
      calc_path
    end
    render
    input
  end

  def defaults
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    grid.width     ||= 15
    grid.height    ||= 15
    grid.cell_size ||= 40
    grid.rect      ||= [0, 0, grid.width, grid.height]

    # At some step the animation will end,
    # and further steps won't change anything (the whole grid.widthill be explored)
    # This step is roughly the grid's width * height
    # When anim_steps equals max_steps no more calculations will occur
    # and the slider will be at the end
    state.max_steps  ||= args.state.grid.width * args.state.grid.height

    # The location of the star and walls of the grid
    # They can be modified to have a different initial grid
    # Walls are stored in a hash for quick look up when doing the search
    state.star   ||= [2, 8]
    state.target ||= [10, 5]
    state.walls  ||= {}

    # Variables that are used by the breadth first search
    # Storing cells that the search has visited, prevents unnecessary steps
    # Expanding the frontier of the search in order makes the search expand
    # from the center outward

    # Visited cells in the first grid
    state.visited               ||= {}
    # Visited cells in the second grid
    state.early_exit_visited    ||= {}
    # The cells from which the search is to expand
    state.frontier              ||= []
    # A hash of where each cell was expanded from
    # The key is a cell, and the value is the cell it came from
    state.came_from             ||= {}
    # Cells that are part of the path from the target to the star
    state.path                  ||= {}

    # What the user is currently editing on the grid
    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    state.current_input ||= :none
  end

  # Draws everything onto the screen
  def render
    render_background
    render_heat_map
    render_walls
    render_path
    render_star
    render_target
    render_labels
  end

  # The methods below subdivide the task of drawing everything to the screen

  # Draws what the grid looks like with nothing on it
  def render_background
    render_unvisited
    render_grid_lines
  end

  # Draws both grids
  def render_unvisited
    outputs.solids << scale_up(grid.rect).merge(unvisited_color)
    outputs.solids << early_exit_scale_up(grid.rect).merge(unvisited_color)
  end

  # Draws grid lines to show the division of the grid into cells
  def render_grid_lines
    outputs.lines << (0..grid.width).map { |x| vertical_line(x) }
    outputs.lines << (0..grid.width).map { |x| early_exit_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| horizontal_line(y) }
    outputs.lines << (0..grid.height).map { |y| early_exit_horizontal_line(y) }
  end

  # Easy way to draw vertical lines given an index
  def vertical_line x
    line = { x: x, y: 0, w: 0, h: grid.height }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Easy way to draw horizontal lines given an index
  def horizontal_line y
    line = { x: 0, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Easy way to draw vertical lines given an index
  def early_exit_vertical_line x
    vertical_line(x + grid.width + 1)
  end

  # Easy way to draw horizontal lines given an index
  def early_exit_horizontal_line y
    line = { x: grid.width + 1, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Draws the walls on both grids
  def render_walls
    state.walls.each_key do |wall|
      outputs.solids << scale_up(wall).merge(wall_color)
      outputs.solids << early_exit_scale_up(wall).merge(wall_color)
    end
  end

  # Renders the star on both grids
  def render_star
    outputs.sprites << scale_up(state.star).merge({path: 'star.png'})
    outputs.sprites << early_exit_scale_up(state.star).merge({path: 'star.png'})
  end

  # Renders the target on both grids
  def render_target
    outputs.sprites << scale_up(state.target).merge({path: 'target.png'})
    outputs.sprites << early_exit_scale_up(state.target).merge({path: 'target.png'})
  end

  # Labels the grids
  def render_labels
    outputs.labels << [200, 625, "Without early exit"]
    outputs.labels << [875, 625, "With early exit"]
  end

  # Renders the path based off of the state.path hash
  def render_path
    # If the star and target are disconnected there will only be one path
    # The path should not render in that case
    unless state.path.size == 1
      state.path.each_key do | cell |
        # Renders path on both grids
        outputs.solids << scale_up(cell).merge(path_color)
        outputs.solids << early_exit_scale_up(cell).merge(path_color)
      end
    end
  end

  # Calculates the path from the target to the star after the search is over
  # Relies on the came_from hash
  # Fills the state.path hash, which is later rendered on screen
  def calc_path
    endpoint = state.target
    while endpoint
      state.path[endpoint] = true
      endpoint = state.came_from[endpoint]
    end
  end

  # Representation of how far away visited cells are from the star
  # Replaces the render_visited method
  # Visually demonstrates the effectiveness of early exit for pathfinding
  def render_heat_map
    state.visited.each_key do | visited_cell |
      distance = (state.star.x - visited_cell.x).abs + (state.star.y - visited_cell.y).abs
      max_distance = grid.width + grid.height
      alpha = 255.to_i * distance.to_i / max_distance.to_i
      heat_color = red.merge({a: alpha })
      outputs.solids << scale_up(visited_cell).merge(heat_color)
    end

    state.early_exit_visited.each_key do | visited_cell |
      distance = (state.star.x - visited_cell.x).abs + (state.star.y - visited_cell.y).abs
      max_distance = grid.width + grid.height
      alpha = 255.to_i * distance.to_i / max_distance.to_i
      heat_color = red.merge({a: alpha })
      outputs.solids << early_exit_scale_up(visited_cell).merge(heat_color)
    end
  end

  # Translates the given cell grid.width + 1 to the right and then scales up
  # Used to draw cells for the second grid
  # This method does not work for lines,
  # so separate methods exist for the grid lines
  def early_exit_scale_up(cell)
    cell_clone = cell.clone
    cell_clone.x += grid.width + 1
    scale_up(cell_clone)
  end

  # In code, the cells are represented as 1x1 rectangles
  # When drawn, the cells are larger than 1x1 rectangles
  # This method is used to scale up cells, and lines
  # Objects are scaled up according to the grid.cell_size variable
  # This allows for easy customization of the visual scale of the grid
  def scale_up(cell)
    if cell.size == 2
      return {
        x: cell.x * grid.cell_size,
        y: cell.y * grid.cell_size,
        w: grid.cell_size,
        h: grid.cell_size
      }
    else
      return {
        x: cell.x * grid.cell_size,
        y: cell.y * grid.cell_size,
        w: cell.w * grid.cell_size,
        h: cell.h * grid.cell_size
      }
    end
  end

  # This method processes user input every tick
  # Any method with "1" is related to the first grid
  # Any method with "2" is related to the second grid
  def input
    # The program has to remember that the user is dragging an object
    # even when the mouse is no longer over that object
    # So detecting input and processing input is separate
    detect_input
    process_input
  end

  # Determines what the user is editing and stores the value
  # Storing the value allows the user to continue the same edit as long as the
  # mouse left click is held
  def detect_input
    # When the mouse is up, nothing is being edited
    if inputs.mouse.up
      state.current_input = :none
    # When the star in the no second grid is clicked
    elsif star_clicked?
      state.current_input = :star
    # When the star in the second grid is clicked
    elsif star2_clicked?
      state.current_input = :star2
    # When the target in the no second grid is clicked
    elsif target_clicked?
      state.current_input = :target
    # When the target in the second grid is clicked
    elsif target2_clicked?
      state.current_input = :target2
    # When a wall in the first grid is clicked
    elsif wall_clicked?
      state.current_input = :remove_wall
    # When a wall in the second grid is clicked
    elsif wall2_clicked?
      state.current_input = :remove_wall2
    # When the first grid is clicked
    elsif grid_clicked?
      state.current_input = :add_wall
    # When the second grid is clicked
    elsif grid2_clicked?
      state.current_input = :add_wall2
    end
  end

  # Processes click and drag based on what the user is currently dragging
  def process_input
    if state.current_input == :star
      input_star
    elsif state.current_input == :star2
      input_star2
    elsif state.current_input == :target
      input_target
    elsif state.current_input == :target2
      input_target2
    elsif state.current_input == :remove_wall
      input_remove_wall
    elsif state.current_input == :remove_wall2
      input_remove_wall2
    elsif state.current_input == :add_wall
      input_add_wall
    elsif state.current_input == :add_wall2
      input_add_wall2
    end
  end

  # Moves the star to the cell closest to the mouse in the first grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def input_star
    old_star = state.star.clone
    state.star = cell_closest_to_mouse
    unless old_star == state.star
      reset_search
    end
  end

  # Moves the star to the cell closest to the mouse in the second grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def input_star2
    old_star = state.star.clone
    state.star = cell_closest_to_mouse2
    unless old_star == state.star
      reset_search
    end
  end

  # Moves the target to the grid closest to the mouse in the first grid
  # Only reset_searchs the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def input_target
    old_target = state.target.clone
    state.target = cell_closest_to_mouse
    unless old_target == state.target
      reset_search
    end
  end

  # Moves the target to the cell closest to the mouse in the second grid
  # Only reset_searchs the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def input_target2
    old_target = state.target.clone
    state.target = cell_closest_to_mouse2
    unless old_target == state.target
      reset_search
    end
  end

  # Removes walls in the first grid that are under the cursor
  def input_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if mouse_inside_grid?
      if state.walls.key?(cell_closest_to_mouse)
        state.walls.delete(cell_closest_to_mouse)
        reset_search
      end
    end
  end

  # Removes walls in the second grid that are under the cursor
  def input_remove_wall2
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if mouse_inside_grid2?
      if state.walls.key?(cell_closest_to_mouse2)
        state.walls.delete(cell_closest_to_mouse2)
        reset_search
      end
    end
  end

  # Adds a wall in the first grid in the cell the mouse is over
  def input_add_wall
    if mouse_inside_grid?
      unless state.walls.key?(cell_closest_to_mouse)
        state.walls[cell_closest_to_mouse] = true
        reset_search
      end
    end
  end


  # Adds a wall in the second grid in the cell the mouse is over
  def input_add_wall2
    if mouse_inside_grid2?
      unless state.walls.key?(cell_closest_to_mouse2)
        state.walls[cell_closest_to_mouse2] = true
        reset_search
      end
    end
  end

  # Whenever the user edits the grid,
  # The search has to be reset_searchd upto the current step
  # with the current grid as the initial state of the grid
  def reset_search
    # Reset_Searchs the search
    state.frontier  = []
    state.visited   = {}
    state.early_exit_visited   = {}
    state.came_from = {}
    state.path      = {}
  end

  # Moves the search forward one step
  def step
    # The setup to the search
    # Runs once when there are no visited cells
    if state.visited.empty?
      state.visited[state.star] = true
      state.early_exit_visited[state.star] = true
      state.frontier << state.star
      state.came_from[state.star] = nil
    end

    # A step in the search
    unless state.frontier.empty?
      # Takes the next frontier cell
      new_frontier = state.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless state.visited.key?(neighbor) || state.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited in the first grid
          state.visited[neighbor] = true
          # Unless the target has been visited
          unless state.visited.key?(state.target)
            # Mark the neighbor as visited in the second grid as well
            state.early_exit_visited[neighbor] = true
          end

          # Add the neighbor to the frontier and remember which cell it came from
          state.frontier << neighbor
          state.came_from[neighbor] = new_frontier
        end
      end
    end
  end


  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors(cell)
    neighbors = []

    # Gets all the valid neighbors into the array
    # From southern neighbor, clockwise
    neighbors << [cell.x, cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y] unless cell.x == 0
    neighbors << [cell.x, cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y] unless cell.x == grid.width - 1

    # Sorts the neighbors so the rendered path is a zigzag path
    # Cells in a diagonal direction are given priority
    # Comment this line to see the difference
    neighbors = neighbors.sort_by { |neighbor_x, neighbor_y|  proximity_to_star(neighbor_x, neighbor_y) }

    neighbors
  end

  # Finds the vertical and horizontal distance of a cell from the star
  # and returns the larger value
  # This method is used to have a zigzag pattern in the rendered path
  # A cell that is [5, 5] from the star,
  # is explored before over a cell that is [0, 7] away.
  # So, if possible, the search tries to go diagonal (zigzag) first
  def proximity_to_star(x, y)
    distance_x = (state.star.x - x).abs
    distance_y = (state.star.y - y).abs

    if distance_x > distance_y
      return distance_x
    else
      return distance_y
    end
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse helps with this
  def cell_closest_to_mouse
    # Closest cell to the mouse in the first grid
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Bound x and y to the grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse in the second grid helps with this
  def cell_closest_to_mouse2
    # Closest cell grid to the mouse in the second
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Translate the cell to the first grid
    x -= grid.width + 1
    # Bound x and y to the first grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # Signal that the user is going to be moving the star from the first grid
  def star_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(scale_up(state.star))
  end

  # Signal that the user is going to be moving the star from the second grid
  def star2_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(early_exit_scale_up(state.star))
  end

  # Signal that the user is going to be moving the target from the first grid
  def target_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(scale_up(state.target))
  end

  # Signal that the user is going to be moving the target from the second grid
  def target2_clicked?
    inputs.mouse.down && inputs.mouse.point.inside_rect?(early_exit_scale_up(state.target))
  end

  # Signal that the user is going to be removing walls from the first grid
  def wall_clicked?
    inputs.mouse.down && mouse_inside_wall?
  end

  # Signal that the user is going to be removing walls from the second grid
  def wall2_clicked?
    inputs.mouse.down && mouse_inside_wall2?
  end

  # Signal that the user is going to be adding walls from the first grid
  def grid_clicked?
    inputs.mouse.down && mouse_inside_grid?
  end

  # Signal that the user is going to be adding walls from the second grid
  def grid2_clicked?
    inputs.mouse.down && mouse_inside_grid2?
  end

  # Returns whether the mouse is inside of a wall in the first grid
  # Part of the condition that checks whether the user is removing a wall
  def mouse_inside_wall?
    state.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(scale_up(wall))
    end

    false
  end

  # Returns whether the mouse is inside of a wall in the second grid
  # Part of the condition that checks whether the user is removing a wall
  def mouse_inside_wall2?
    state.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(early_exit_scale_up(wall))
    end

    false
  end

  # Returns whether the mouse is inside of the first grid
  # Part of the condition that checks whether the user is adding a wall
  def mouse_inside_grid?
    inputs.mouse.point.inside_rect?(scale_up(grid.rect))
  end

  # Returns whether the mouse is inside of the second grid
  # Part of the condition that checks whether the user is adding a wall
  def mouse_inside_grid2?
    inputs.mouse.point.inside_rect?(early_exit_scale_up(grid.rect))
  end

  # These methods provide handy aliases to colors

  # Light brown
  def unvisited_color
    [221, 212, 213]
    { r: 221, g: 212, b: 213 }
  end

  # Camo Green
  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  # Pastel White
  def path_color
    { r: 231, g: 230, b: 228 }
  end

  def red
    { r: 255, g: 0, b: 0 }
  end

  # Makes code more concise
  def grid
    state.grid
  end
end

# Method that is called by DragonRuby periodically
# Used for updating animations and calculations
def tick args

  # Pressing r will reset the application
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  # Every tick, new args are passed, and the Breadth First Search tick is called
  $early_exit_breadth_first_search ||= EarlyExitBreadthFirstSearch.new
  $early_exit_breadth_first_search.args = args
  $early_exit_breadth_first_search.tick
end


def reset
  $early_exit_breadth_first_search = nil
end

    Dijkstra - main.rb link

    # ./samples/13_path_finding_algorithms/05_dijkstra/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# Demonstrates how Dijkstra's Algorithm allows movement costs to be considered

# Inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html

# The first grid is a breadth first search with an early exit.
# It shows a heat map of all the cells that were visited by the search and their relative distance.

# The second grid is an implementation of Dijkstra's algorithm.
# Light green cells have 5 times the movement cost of regular cells.
# The heat map will darken based on movement cost.

# Dark green cells are walls, and the search cannot go through them.
class Movement_Costs
  attr_gtk

  # This method is called every frame/tick
  # Every tick, the current state of the search is rendered on the screen,
  # User input is processed, and
  # The next step in the search is calculated
  def tick
    defaults
    render
    input
    calc
  end

  def defaults
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    grid.width     ||= 10
    grid.height    ||= 10
    grid.cell_size ||= 60
    grid.rect      ||= [0, 0, grid.width, grid.height]

    # The location of the star and walls of the grid
    # They can be modified to have a different initial grid
    # Walls are stored in a hash for quick look up when doing the search
    state.star   ||= [1, 5]
    state.target ||= [8, 4]
    state.walls  ||= {[1, 1] => true, [2, 1] => true, [3, 1] => true, [1, 2] => true, [2, 2] => true, [3, 2] => true}
    state.hills  ||= {
      [4, 1] => true,
      [5, 1] => true,
      [4, 2] => true,
      [5, 2] => true,
      [6, 2] => true,
      [4, 3] => true,
      [5, 3] => true,
      [6, 3] => true,
      [3, 4] => true,
      [4, 4] => true,
      [5, 4] => true,
      [6, 4] => true,
      [7, 4] => true,
      [3, 5] => true,
      [4, 5] => true,
      [5, 5] => true,
      [6, 5] => true,
      [7, 5] => true,
      [4, 6] => true,
      [5, 6] => true,
      [6, 6] => true,
      [7, 6] => true,
      [4, 7] => true,
      [5, 7] => true,
      [6, 7] => true,
      [4, 8] => true,
      [5, 8] => true,
    }

    # What the user is currently editing on the grid
    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    state.user_input ||= :none

    # Values that are used for the breadth first search
    # Keeping track of what cells were visited prevents counting cells multiple times
    breadth_first_search.visited    ||= {}
    # The cells from which the breadth first search will expand
    breadth_first_search.frontier   ||= []
    # Keeps track of which cell all cells were searched from
    # Used to recreate the path from the target to the star
    breadth_first_search.came_from  ||= {}

    # Keeps track of the movement cost so far to be at a cell
    # Allows the costs of new cells to be quickly calculated
    # Also doubles as a way to check if cells have already been visited
    dijkstra_search.cost_so_far ||= {}
    # The cells from which the Dijkstra search will expand
    dijkstra_search.frontier    ||= []
    # Keeps track of which cell all cells were searched from
    # Used to recreate the path from the target to the star
    dijkstra_search.came_from   ||= {}
  end

  # Draws everything onto the screen
  def render
    render_background

    render_heat_maps

    render_star
    render_target
    render_hills
    render_walls

    render_paths
  end
  # The methods below subdivide the task of drawing everything to the screen

  # Draws what the grid looks like with nothing on it
  def render_background
    render_unvisited
    render_grid_lines
    render_labels
  end

  # Draws two rectangles the size of the grid in the default cell color
  # Used as part of the background
  def render_unvisited
    outputs.solids << scale_up(grid.rect).merge(unvisited_color)
    outputs.solids << move_and_scale_up(grid.rect).merge(unvisited_color)
  end

  # Draws grid lines to show the division of the grid into cells
  def render_grid_lines
    outputs.lines << (0..grid.width).map { |x| vertical_line(x) }
    outputs.lines << (0..grid.width).map { |x| shifted_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| horizontal_line(y) }
    outputs.lines << (0..grid.height).map { |y| shifted_horizontal_line(y) }
  end

  # A line the size of the grid, multiplied by the cell size for rendering
  def vertical_line x
    line = { x: x, y: 0, w: 0, h: grid.height }
    line.transform_values { |v| v * grid.cell_size }
  end

  # A line the size of the grid, multiplied by the cell size for rendering
  def horizontal_line y
    line = { x: 0, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Translate vertical line by the size of the grid and 1
  def shifted_vertical_line x
    vertical_line(x + grid.width + 1)
  end

  # Get horizontal line and shift to the right
  def shifted_horizontal_line y
    line = { x: grid.width + 1, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Labels the grids
  def render_labels
    outputs.labels << [175, 650, "Number of steps", 3]
    outputs.labels << [925, 650, "Distance", 3]
  end

  def render_paths
    render_breadth_first_search_path
    render_dijkstra_path
  end

  def render_heat_maps
    render_breadth_first_search_heat_map
    render_dijkstra_heat_map
  end

  # This heat map shows the cells explored by the breadth first search and how far they are from the star.
  def render_breadth_first_search_heat_map
    # For each cell explored
    breadth_first_search.visited.each_key do | visited_cell |
      # Find its distance from the star
      distance = (state.star.x - visited_cell.x).abs + (state.star.y - visited_cell.y).abs
      max_distance = grid.width + grid.height
      # Get it as a percent of the maximum distance and scale to 255 for use as an alpha value
      alpha = 255.to_i * distance.to_i / max_distance.to_i
      heat_color = red.merge({a: alpha })
      outputs.solids << scale_up(visited_cell).merge(heat_color)
    end
  end

  def render_breadth_first_search_path
    # If the search found the target
    if breadth_first_search.visited.has_key?(state.target)
      # Start from the target
      endpoint = state.target
      # And the cell it came from
      next_endpoint = breadth_first_search.came_from[endpoint]
      while endpoint && next_endpoint
        # Draw a path between these two cells
        path = get_path_between(endpoint, next_endpoint)
        outputs.solids << scale_up(path).merge(path_color)
        # And get the next pair of cells
        endpoint = next_endpoint
        next_endpoint = breadth_first_search.came_from[endpoint]
        # Continue till there are no more cells
      end
    end
  end

  def render_dijkstra_heat_map
    dijkstra_search.cost_so_far.each do |visited_cell, cost|
      max_cost = (grid.width + grid.height) #* 5
      alpha = 255.to_i * cost.to_i / max_cost.to_i
      heat_color = red.merge({a: alpha})
      outputs.solids << move_and_scale_up(visited_cell).merge(heat_color)
    end
  end

  def render_dijkstra_path
    # If the search found the target
    if dijkstra_search.came_from.has_key?(state.target)
      # Get the target and the cell it came from
      endpoint = state.target
      next_endpoint = dijkstra_search.came_from[endpoint]
      while endpoint && next_endpoint
        # Draw a path between them
        path = get_path_between(endpoint, next_endpoint)
        outputs.solids << move_and_scale_up(path).merge(path_color)

        # Shift one cell down the path
        endpoint = next_endpoint
        next_endpoint = dijkstra_search.came_from[endpoint]

        # Repeat till the end of the path
      end
    end
  end

  # Renders the star on both grids
  def render_star
    outputs.sprites << scale_up(state.star).merge({path: 'star.png'})
    outputs.sprites << move_and_scale_up(state.star).merge({path: 'star.png'})
  end

  # Renders the target on both grids
  def render_target
    outputs.sprites << scale_up(state.target).merge({path: 'target.png'})
    outputs.sprites << move_and_scale_up(state.target).merge({path: 'target.png'})
  end

  def render_hills
    state.hills.each_key do |hill|
      outputs.solids << scale_up(hill).merge(hill_color)
      outputs.solids << move_and_scale_up(hill).merge(hill_color)
    end
  end

  # Draws the walls on both grids
  def render_walls
    state.walls.each_key do |wall|
      outputs.solids << scale_up(wall).merge(wall_color)
      outputs.solids << move_and_scale_up(wall).merge(wall_color)
    end
  end

  def get_path_between(cell_one, cell_two)
    path = nil
    if cell_one.x == cell_two.x
      if cell_one.y < cell_two.y
        path = [cell_one.x + 0.3, cell_one.y + 0.3, 0.4, 1.4]
      else
        path = [cell_two.x + 0.3, cell_two.y + 0.3, 0.4, 1.4]
      end
    else
      if cell_one.x < cell_two.x
        path = [cell_one.x + 0.3, cell_one.y + 0.3, 1.4, 0.4]
      else
        path = [cell_two.x + 0.3, cell_two.y + 0.3, 1.4, 0.4]
      end
    end
    path
  end

  # Translates the given cell grid.width + 1 to the right and then scales up
  # Used to draw cells for the second grid
  # This method does not work for lines,
  # so separate methods exist for the grid lines
  def move_and_scale_up(cell)
    cell_clone = cell.clone
    cell_clone.x += grid.width + 1
    scale_up(cell_clone)
  end

  # In code, the cells are represented as 1x1 rectangles
  # When drawn, the cells are larger than 1x1 rectangles
  # This method is used to scale up cells, and lines
  # Objects are scaled up according to the grid.cell_size variable
  # This allows for easy customization of the visual scale of the grid
  def scale_up(cell)
    if cell.size == 2
      return {
        x: cell.x * grid.cell_size,
        y: cell.y * grid.cell_size,
        w: grid.cell_size,
        h: grid.cell_size
      }
    else
      return {
        x: cell.x * grid.cell_size,
        y: cell.y * grid.cell_size,
        w: cell.w * grid.cell_size,
        h: cell.h * grid.cell_size
      }
    end
  end

  # Handles user input every tick so the grid can be edited
  # Separate input detection and processing is needed
  # For example: Adding walls is started by clicking down on a hill,
  # but the mouse doesn't need to remain over hills to add walls
  def input
    # If the mouse was lifted this tick
    if inputs.mouse.up
      # Set current input to none
      state.user_input = :none
    end

    # If the mouse was clicked this tick
    if inputs.mouse.down
      # Determine what the user is editing and edit the state.user_input variable
      determine_input
    end

    # Process user input based on user_input variable and current mouse position
    process_input
  end

  # Determines what the user is editing and stores the value
  # This method is called the tick the mouse is clicked
  # Storing the value allows the user to continue the same edit as long as the
  # mouse left click is held
  def determine_input
    # If the mouse is over the star in the first grid
    if mouse_over_star?
      # The user is editing the star from the first grid
      state.user_input = :star
    # If the mouse is over the star in the second grid
    elsif mouse_over_star2?
      # The user is editing the star from the second grid
      state.user_input = :star2
    # If the mouse is over the target in the first grid
    elsif mouse_over_target?
      # The user is editing the target from the first grid
      state.user_input = :target
    # If the mouse is over the target in the second grid
    elsif mouse_over_target2?
      # The user is editing the target from the second grid
      state.user_input = :target2
    # If the mouse is over a wall in the first grid
    elsif mouse_over_wall?
      # The user is removing a wall from the first grid
      state.user_input = :remove_wall
    # If the mouse is over a wall in the second grid
    elsif mouse_over_wall2?
      # The user is removing a wall from the second grid
      state.user_input = :remove_wall2
    # If the mouse is over a hill in the first grid
    elsif mouse_over_hill?
      # The user is adding a wall from the first grid
      state.user_input = :add_wall
    # If the mouse is over a hill in the second grid
    elsif mouse_over_hill2?
      # The user is adding a wall from the second grid
      state.user_input = :add_wall2
    # If the mouse is over the first grid
    elsif mouse_over_grid?
      # The user is adding a hill from the first grid
      state.user_input = :add_hill
    # If the mouse is over the second grid
    elsif mouse_over_grid2?
      # The user is adding a hill from the second grid
      state.user_input = :add_hill2
    end
  end

  # Processes click and drag based on what the user is currently dragging
  def process_input
    if state.user_input == :star
      input_star
    elsif state.user_input == :star2
      input_star2
    elsif state.user_input == :target
      input_target
    elsif state.user_input == :target2
      input_target2
    elsif state.user_input == :remove_wall
      input_remove_wall
    elsif state.user_input == :remove_wall2
      input_remove_wall2
    elsif state.user_input == :add_hill
      input_add_hill
    elsif state.user_input == :add_hill2
      input_add_hill2
    elsif state.user_input == :add_wall
      input_add_wall
    elsif state.user_input == :add_wall2
      input_add_wall2
    end
  end

  # Calculates the two searches
  def calc
    # If the searches have not started
    if breadth_first_search.visited.empty?
      # Calculate the two searches
      calc_breadth_first
      calc_dijkstra
    end
  end


  def calc_breadth_first
    # Sets up the Breadth First Search
    breadth_first_search.visited[state.star]   = true
    breadth_first_search.frontier              << state.star
    breadth_first_search.came_from[state.star] = nil

    until breadth_first_search.frontier.empty?
      return if breadth_first_search.visited.key?(state.target)
      # A step in the search
      # Takes the next frontier cell
      new_frontier = breadth_first_search.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do | neighbor |
        # That have not been visited and are not walls
        unless breadth_first_search.visited.key?(neighbor) || state.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited in the first grid
          breadth_first_search.visited[neighbor] = true
          breadth_first_search.frontier << neighbor
          # Remember which cell the neighbor came from
          breadth_first_search.came_from[neighbor] = new_frontier
        end
      end
    end
  end

  # Calculates the Dijkstra Search from the beginning to the end

  def calc_dijkstra
    # The initial values for the Dijkstra search
    dijkstra_search.frontier                << [state.star, 0]
    dijkstra_search.came_from[state.star]   = nil
    dijkstra_search.cost_so_far[state.star] = 0

    # Until their are no more cells to be explored
    until dijkstra_search.frontier.empty?
      # Get the next cell to be explored from
      # We get the first element of the array which is the cell. The second element is the priority.
      current = dijkstra_search.frontier.shift[0]

      # Stop the search if we found the target
      return if current == state.target

      # For each of the neighbors
      adjacent_neighbors(current).each do | neighbor |
        # Unless this cell is a wall or has already been explored.
        unless dijkstra_search.came_from.key?(neighbor) or state.walls.key?(neighbor)
          # Calculate the movement cost of getting to this cell and memo
          new_cost = dijkstra_search.cost_so_far[current] + cost(neighbor)
          dijkstra_search.cost_so_far[neighbor] = new_cost

          # Add this neighbor to the cells too be explored
          dijkstra_search.frontier << [neighbor, new_cost]
          dijkstra_search.came_from[neighbor] = current
        end
      end

      # Sort the frontier so exploration occurs that have a low cost so far.
      # My implementation of a priority queue
      dijkstra_search.frontier = dijkstra_search.frontier.sort_by {|cell, priority| priority}
    end
  end

  def cost(cell)
    return 5 if state.hills.key? cell
    1
  end




  # Moves the star to the cell closest to the mouse in the first grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def input_star
    old_star = state.star.clone
    unless cell_closest_to_mouse == state.target
      state.star = cell_closest_to_mouse
    end
    unless old_star == state.star
      reset_search
    end
  end

  # Moves the star to the cell closest to the mouse in the second grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def input_star2
    old_star = state.star.clone
    unless cell_closest_to_mouse2 == state.target
      state.star = cell_closest_to_mouse2
    end
    unless old_star == state.star
      reset_search
    end
  end

  # Moves the target to the grid closest to the mouse in the first grid
  # Only reset_searchs the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def input_target
    old_target = state.target.clone
    unless cell_closest_to_mouse == state.star
      state.target = cell_closest_to_mouse
    end
    unless old_target == state.target
      reset_search
    end
  end

  # Moves the target to the cell closest to the mouse in the second grid
  # Only reset_searchs the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def input_target2
    old_target = state.target.clone
    unless cell_closest_to_mouse2 == state.star
      state.target = cell_closest_to_mouse2
    end
    unless old_target == state.target
      reset_search
    end
  end

  # Removes walls in the first grid that are under the cursor
  def input_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if mouse_over_grid?
      if state.walls.key?(cell_closest_to_mouse) or state.hills.key?(cell_closest_to_mouse)
        state.walls.delete(cell_closest_to_mouse)
        state.hills.delete(cell_closest_to_mouse)
        reset_search
      end
    end
  end

  # Removes walls in the second grid that are under the cursor
  def input_remove_wall2
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if mouse_over_grid2?
      if state.walls.key?(cell_closest_to_mouse2) or state.hills.key?(cell_closest_to_mouse2)
        state.walls.delete(cell_closest_to_mouse2)
        state.hills.delete(cell_closest_to_mouse2)
        reset_search
      end
    end
  end

  # Adds a hill in the first grid in the cell the mouse is over
  def input_add_hill
    if mouse_over_grid?
      unless state.hills.key?(cell_closest_to_mouse)
        state.hills[cell_closest_to_mouse] = true
        reset_search
      end
    end
  end


  # Adds a hill in the second grid in the cell the mouse is over
  def input_add_hill2
    if mouse_over_grid2?
      unless state.hills.key?(cell_closest_to_mouse2)
        state.hills[cell_closest_to_mouse2] = true
        reset_search
      end
    end
  end

  # Adds a wall in the first grid in the cell the mouse is over
  def input_add_wall
    if mouse_over_grid?
      unless state.walls.key?(cell_closest_to_mouse)
        state.hills.delete(cell_closest_to_mouse)
        state.walls[cell_closest_to_mouse] = true
        reset_search
      end
    end
  end

  # Adds a wall in the second grid in the cell the mouse is over
  def input_add_wall2
    if mouse_over_grid2?
      unless state.walls.key?(cell_closest_to_mouse2)
        state.hills.delete(cell_closest_to_mouse2)
        state.walls[cell_closest_to_mouse2] = true
        reset_search
      end
    end
  end

  # Whenever the user edits the grid,
  # The search has to be reset_searchd upto the current step
  # with the current grid as the initial state of the grid
  def reset_search
    breadth_first_search.visited    = {}
    breadth_first_search.frontier   = []
    breadth_first_search.came_from  = {}

    dijkstra_search.frontier    = []
    dijkstra_search.came_from   = {}
    dijkstra_search.cost_so_far = {}
  end



  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors(cell)
    neighbors = []

    # Gets all the valid neighbors into the array
    # From southern neighbor, clockwise
    neighbors << [cell.x    , cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y    ] unless cell.x == 0
    neighbors << [cell.x    , cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y    ] unless cell.x == grid.width - 1

    # Sorts the neighbors so the rendered path is a zigzag path
    # Cells in a diagonal direction are given priority
    # Comment this line to see the difference
    neighbors = neighbors.sort_by { |neighbor_x, neighbor_y|  proximity_to_star(neighbor_x, neighbor_y) }

    neighbors
  end

  # Finds the vertical and horizontal distance of a cell from the star
  # and returns the larger value
  # This method is used to have a zigzag pattern in the rendered path
  # A cell that is [5, 5] from the star,
  # is explored before over a cell that is [0, 7] away.
  # So, if possible, the search tries to go diagonal (zigzag) first
  def proximity_to_star(x, y)
    distance_x = (state.star.x - x).abs
    distance_y = (state.star.y - y).abs

    if distance_x > distance_y
      return distance_x
    else
      return distance_y
    end
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse helps with this
  def cell_closest_to_mouse
    # Closest cell to the mouse in the first grid
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Bound x and y to the grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse in the second grid helps with this
  def cell_closest_to_mouse2
    # Closest cell grid to the mouse in the second
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Translate the cell to the first grid
    x -= grid.width + 1
    # Bound x and y to the first grid
    x = 0 if x < 0
    y = 0 if y < 0
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # Signal that the user is going to be moving the star from the first grid
  def mouse_over_star?
    inputs.mouse.point.inside_rect?(scale_up(state.star))
  end

  # Signal that the user is going to be moving the star from the second grid
  def mouse_over_star2?
    inputs.mouse.point.inside_rect?(move_and_scale_up(state.star))
  end

  # Signal that the user is going to be moving the target from the first grid
  def mouse_over_target?
    inputs.mouse.point.inside_rect?(scale_up(state.target))
  end

  # Signal that the user is going to be moving the target from the second grid
  def mouse_over_target2?
    inputs.mouse.point.inside_rect?(move_and_scale_up(state.target))
  end

  # Signal that the user is going to be removing walls from the first grid
  def mouse_over_wall?
    state.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be removing walls from the second grid
  def mouse_over_wall2?
    state.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(move_and_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be removing hills from the first grid
  def mouse_over_hill?
    state.hills.each_key do | hill |
      return true if inputs.mouse.point.inside_rect?(scale_up(hill))
    end

    false
  end

  # Signal that the user is going to be removing hills from the second grid
  def mouse_over_hill2?
    state.hills.each_key do | hill |
      return true if inputs.mouse.point.inside_rect?(move_and_scale_up(hill))
    end

    false
  end

  # Signal that the user is going to be adding walls from the first grid
  def mouse_over_grid?
    inputs.mouse.point.inside_rect?(scale_up(grid.rect))
  end

  # Signal that the user is going to be adding walls from the second grid
  def mouse_over_grid2?
    inputs.mouse.point.inside_rect?(move_and_scale_up(grid.rect))
  end

  # These methods provide handy aliases to colors

  # Light brown
  def unvisited_color
    { r: 221, g: 212, b: 213 }
  end

  # Camo Green
  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  # Pastel White
  def path_color
    { r: 231, g: 230, b: 228 }
  end

  def red
    { r: 255, g: 0, b: 0 }
  end

  # A Green
  def hill_color
    { r: 139, g: 173, b: 132 }
  end

  # Makes code more concise
  def grid
    state.grid
  end

  def breadth_first_search
    state.breadth_first_search
  end

  def dijkstra_search
    state.dijkstra_search
  end
end

# Method that is called by DragonRuby periodically
# Used for updating animations and calculations
def tick args

  # Pressing r will reset the application
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  # Every tick, new args are passed, and the Dijkstra tick method is called
  $movement_costs ||= Movement_Costs.new
  $movement_costs.args = args
  $movement_costs.tick
end


def reset
  $movement_costs = nil
end

    Heuristic - main.rb link

    # ./samples/13_path_finding_algorithms/06_heuristic/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# This program is inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html
# The effectiveness of the Heuristic search algorithm is shown through this demonstration.
# Notice that both searches find the shortest path
# The heuristic search, however, explores less of the grid, and is therefore faster.
# The heuristic search prioritizes searching cells that are closer to the target.
# Make sure to look at the Heuristic with walls program to see some of the downsides of the heuristic algorithm.

class Heuristic
  attr_gtk

  def tick
    defaults
    render
    input
    # If animation is playing, and max steps have not been reached
    # Move the search a step forward
    if state.play && state.current_step < state.max_steps
      # Variable that tells the program what step to recalculate up to
      state.current_step += 1
      move_searches_one_step_forward
    end
  end

  def defaults
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    grid.width     ||= 15
    grid.height    ||= 15
    grid.cell_size ||= 40
    grid.rect      ||= [0, 0, grid.width, grid.height]

    grid.star      ||= [0, 2]
    grid.target    ||= [14, 12]
    grid.walls     ||= {}
    # There are no hills in the Heuristic Search Demo

    # What the user is currently editing on the grid
    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    state.user_input ||= :none

    # These variables allow the breadth first search to take place
    # Came_from is a hash with a key of a cell and a value of the cell that was expanded from to find the key.
    # Used to prevent searching cells that have already been found
    # and to trace a path from the target back to the starting point.
    # Frontier is an array of cells to expand the search from.
    # The search is over when there are no more cells to search from.
    # Path stores the path from the target to the star, once the target has been found
    # It prevents calculating the path every tick.
    bfs.came_from  ||= {}
    bfs.frontier   ||= []
    bfs.path       ||= []

    heuristic.came_from ||= {}
    heuristic.frontier  ||= []
    heuristic.path      ||= []

    # Stores which step of the animation is being rendered
    # When the user moves the star or messes with the walls,
    # the searches are recalculated up to this step
    unless state.current_step
      state.current_step = 0
    end

    # At some step the animation will end,
    # and further steps won't change anything (the whole grid will be explored)
    # This step is roughly the grid's width * height
    # When anim_steps equals max_steps no more calculations will occur
    # and the slider will be at the end
    state.max_steps = grid.width * grid.height

    # Whether the animation should play or not
    # If true, every tick moves anim_steps forward one
    # Pressing the stepwise animation buttons will pause the animation
    # An if statement instead of the ||= operator is used for assigning a boolean value.
    # The || operator does not differentiate between nil and false.
    if state.play == nil
      state.play = false
    end

    # Store the rects of the buttons that control the animation
    # They are here for user customization
    # Editing these might require recentering the text inside them
    # Those values can be found in the render_button methods
    buttons.left   = [470, 600, 50, 50]
    buttons.center = [520, 600, 200, 50]
    buttons.right  = [720, 600, 50, 50]

    # The variables below are related to the slider
    # They allow the user to customize them
    # They also give a central location for the render and input methods to get
    # information from
    # x & y are the coordinates of the leftmost part of the slider line
    slider.x = 440
    slider.y = 675
    # This is the width of the line
    slider.w = 360
    # This is the offset for the circle
    # Allows the center of the circle to be on the line,
    # as opposed to the upper right corner
    slider.offset = 20
    # This is the spacing between each of the notches on the slider
    # Notches are places where the circle can rest on the slider line
    # There needs to be a notch for each step before the maximum number of steps
    slider.spacing = slider.w.to_f / state.max_steps.to_f
  end

  # All methods with render draw stuff on the screen
  # UI has buttons, the slider, and labels
  # The search specific rendering occurs in the respective methods
  def render
    render_ui
    render_bfs
    render_heuristic
  end

  def render_ui
    render_buttons
    render_slider
    render_labels
  end

  def render_buttons
    render_left_button
    render_center_button
    render_right_button
  end

  def render_bfs
    render_bfs_grid
    render_bfs_star
    render_bfs_target
    render_bfs_visited
    render_bfs_walls
    render_bfs_frontier
    render_bfs_path
  end

  def render_heuristic
    render_heuristic_grid
    render_heuristic_star
    render_heuristic_target
    render_heuristic_visited
    render_heuristic_walls
    render_heuristic_frontier
    render_heuristic_path
  end

  # This method handles user input every tick
  def input
    # Check and handle button input
    input_buttons

    # If the mouse was lifted this tick
    if inputs.mouse.up
      # Set current input to none
      state.user_input = :none
    end

    # If the mouse was clicked this tick
    if inputs.mouse.down
      # Determine what the user is editing and appropriately edit the state.user_input variable
      determine_input
    end

    # Process user input based on user_input variable and current mouse position
    process_input
  end

  # Determines what the user is editing
  # This method is called when the mouse is clicked down
  def determine_input
    if mouse_over_slider?
      state.user_input = :slider
    # If the mouse is over the star in the first grid
    elsif bfs_mouse_over_star?
      # The user is editing the star from the first grid
      state.user_input = :bfs_star
    # If the mouse is over the star in the second grid
    elsif heuristic_mouse_over_star?
      # The user is editing the star from the second grid
      state.user_input = :heuristic_star
    # If the mouse is over the target in the first grid
    elsif bfs_mouse_over_target?
      # The user is editing the target from the first grid
      state.user_input = :bfs_target
    # If the mouse is over the target in the second grid
    elsif heuristic_mouse_over_target?
      # The user is editing the target from the second grid
      state.user_input = :heuristic_target
    # If the mouse is over a wall in the first grid
    elsif bfs_mouse_over_wall?
      # The user is removing a wall from the first grid
      state.user_input = :bfs_remove_wall
    # If the mouse is over a wall in the second grid
    elsif heuristic_mouse_over_wall?
      # The user is removing a wall from the second grid
      state.user_input = :heuristic_remove_wall
    # If the mouse is over the first grid
    elsif bfs_mouse_over_grid?
      # The user is adding a wall from the first grid
      state.user_input = :bfs_add_wall
    # If the mouse is over the second grid
    elsif heuristic_mouse_over_grid?
      # The user is adding a wall from the second grid
      state.user_input = :heuristic_add_wall
    end
  end

  # Processes click and drag based on what the user is currently dragging
  def process_input
    if state.user_input == :slider
      process_input_slider
    elsif state.user_input == :bfs_star
      process_input_bfs_star
    elsif state.user_input == :heuristic_star
      process_input_heuristic_star
    elsif state.user_input == :bfs_target
      process_input_bfs_target
    elsif state.user_input == :heuristic_target
      process_input_heuristic_target
    elsif state.user_input == :bfs_remove_wall
      process_input_bfs_remove_wall
    elsif state.user_input == :heuristic_remove_wall
      process_input_heuristic_remove_wall
    elsif state.user_input == :bfs_add_wall
      process_input_bfs_add_wall
    elsif state.user_input == :heuristic_add_wall
      process_input_heuristic_add_wall
    end
  end

  def render_slider
    # Using primitives hides the line under the white circle of the slider
    # Draws the line
    outputs.primitives << [slider.x, slider.y, slider.x + slider.w, slider.y].line
    # The circle needs to be offset so that the center of the circle
    # overlaps the line instead of the upper right corner of the circle
    # The circle's x value is also moved based on the current seach step
    circle_x = (slider.x - slider.offset) + (state.current_step * slider.spacing)
    circle_y = (slider.y - slider.offset)
    circle_rect = [circle_x, circle_y, 37, 37]
    outputs.primitives << [circle_rect, 'circle-white.png'].sprite
  end

  def render_labels
    outputs.labels << [205, 625, "Breadth First Search"]
    outputs.labels << [820, 625, "Heuristic Best-First Search"]
  end

  def render_left_button
    # Draws the button_color button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.left, button_color]
    outputs.borders << [buttons.left]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    # If the button size is changed, the label might need to be edited as well
    # to keep the label in the center of the button
    label_x = buttons.left.x + 20
    label_y = buttons.left.y + 35
    outputs.labels  << [label_x, label_y, "<"]
  end

  def render_center_button
    # Draws the button_color button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.center, button_color]
    outputs.borders << [buttons.center]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    # If the button size is changed, the label might need to be edited as well
    # to keep the label in the center of the button
    label_x    = buttons.center.x + 37
    label_y    = buttons.center.y + 35
    label_text = state.play ? "Pause Animation" : "Play Animation"
    outputs.labels << [label_x, label_y, label_text]
  end

  def render_right_button
    # Draws the button_color button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.right, button_color]
    outputs.borders << [buttons.right]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    label_x = buttons.right.x + 20
    label_y = buttons.right.y + 35
    outputs.labels  << [label_x, label_y, ">"]
  end

  def render_bfs_grid
    # A large rect the size of the grid
    outputs.solids << bfs_scale_up(grid.rect).merge(default_color)

    outputs.lines << (0..grid.width).map { |x| bfs_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| bfs_horizontal_line(y) }
  end

  def render_heuristic_grid
    # A large rect the size of the grid
    outputs.solids << heuristic_scale_up(grid.rect).merge(default_color)

    outputs.lines << (0..grid.width).map { |x| heuristic_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| heuristic_horizontal_line(y) }
  end

  # Returns a vertical line for a column of the first grid
  def bfs_vertical_line x
    line = { x: x, y: 0, w: 0, h: grid.height }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Returns a horizontal line for a column of the first grid
  def bfs_horizontal_line y
    line = { x: 0, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Returns a vertical line for a column of the second grid
  def heuristic_vertical_line x
    bfs_vertical_line(x + grid.width + 1)
  end

  # Returns a horizontal line for a column of the second grid
  def heuristic_horizontal_line y
    line = { x: grid.width + 1, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Renders the star on the first grid
  def render_bfs_star
    outputs.sprites << bfs_scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the star on the second grid
  def render_heuristic_star
    outputs.sprites << heuristic_scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the target on the first grid
  def render_bfs_target
    outputs.sprites << bfs_scale_up(grid.target).merge({ path: 'target.png' })
  end

  # Renders the target on the second grid
  def render_heuristic_target
    outputs.sprites << heuristic_scale_up(grid.target).merge({ path: 'target.png' })
  end

  # Renders the walls on the first grid
  def render_bfs_walls
    outputs.solids << grid.walls.map do |key, value|
      bfs_scale_up(key).merge(wall_color)
    end
  end

  # Renders the walls on the second grid
  def render_heuristic_walls
    outputs.solids << grid.walls.map do |key, value|
      heuristic_scale_up(key).merge(wall_color)
    end
  end

  # Renders the visited cells on the first grid
  def render_bfs_visited
    outputs.solids << bfs.came_from.map do |key, value|
      bfs_scale_up(key).merge(visited_color)
    end
  end

  # Renders the visited cells on the second grid
  def render_heuristic_visited
    outputs.solids << heuristic.came_from.map do |key, value|
      heuristic_scale_up(key).merge(visited_color)
    end
  end

  # Renders the frontier cells on the first grid
  def render_bfs_frontier
    outputs.solids << bfs.frontier.map do |cell|
      bfs_scale_up(cell).merge(frontier_color)
    end
  end

  # Renders the frontier cells on the second grid
  def render_heuristic_frontier
    outputs.solids << heuristic.frontier.map do |cell|
      heuristic_scale_up(cell).merge(frontier_color)
    end
  end

  # Renders the path found by the breadth first search on the first grid
  def render_bfs_path
    outputs.solids << bfs.path.map do |path|
      bfs_scale_up(path).merge(path_color)
    end
  end

  # Renders the path found by the heuristic search on the second grid
  def render_heuristic_path
    outputs.solids << heuristic.path.map do |path|
      heuristic_scale_up(path).merge(path_color)
    end
  end

  # Returns the rect for the path between two cells based on their relative positions
  def get_path_between(cell_one, cell_two)
    path = nil

    # If cell one is above cell two
    if cell_one.x == cell_two.x && cell_one.y > cell_two.y
      # Path starts from the center of cell two and moves upward to the center of cell one
      path = [cell_two.x + 0.3, cell_two.y + 0.3, 0.4, 1.4]
    # If cell one is below cell two
    elsif cell_one.x == cell_two.x && cell_one.y < cell_two.y
      # Path starts from the center of cell one and moves upward to the center of cell two
      path = [cell_one.x + 0.3, cell_one.y + 0.3, 0.4, 1.4]
    # If cell one is to the left of cell two
    elsif cell_one.x > cell_two.x && cell_one.y == cell_two.y
      # Path starts from the center of cell two and moves rightward to the center of cell one
      path = [cell_two.x + 0.3, cell_two.y + 0.3, 1.4, 0.4]
    # If cell one is to the right of cell two
    elsif cell_one.x < cell_two.x && cell_one.y == cell_two.y
      # Path starts from the center of cell one and moves rightward to the center of cell two
      path = [cell_one.x + 0.3, cell_one.y + 0.3, 1.4, 0.4]
    end

    path
  end

  # In code, the cells are represented as 1x1 rectangles
  # When drawn, the cells are larger than 1x1 rectangles
  # This method is used to scale up cells, and lines
  # Objects are scaled up according to the grid.cell_size variable
  # This allows for easy customization of the visual scale of the grid
  # This method scales up cells for the first grid
  def bfs_scale_up(cell)
    x = cell.x * grid.cell_size
    y = cell.y * grid.cell_size
    w = cell.w.zero? ? grid.cell_size : cell.w * grid.cell_size
    h = cell.h.zero? ? grid.cell_size : cell.h * grid.cell_size
    {x: x, y: y, w: w, h: h}
    # {x:, y:, w:, h:}
  end

  # Translates the given cell grid.width + 1 to the right and then scales up
  # Used to draw cells for the second grid
  # This method does not work for lines,
  # so separate methods exist for the grid lines
  def heuristic_scale_up(cell)
    # Prevents the original value of cell from being edited
    cell = cell.clone
    # Translates the cell to the second grid equivalent
    cell.x += grid.width + 1
    # Proceeds as if scaling up for the first grid
    bfs_scale_up(cell)
  end

  # Checks and handles input for the buttons
  # Called when the mouse is lifted
  def input_buttons
    input_left_button
    input_center_button
    input_right_button
  end

  # Checks if the previous step button is clicked
  # If it is, it pauses the animation and moves the search one step backward
  def input_left_button
    if left_button_clicked?
      state.play = false
      state.current_step -= 1
      recalculate_searches
    end
  end

  # Controls the play/pause button
  # Inverses whether the animation is playing or not when clicked
  def input_center_button
    if center_button_clicked? || inputs.keyboard.key_down.space
      state.play = !state.play
    end
  end

  # Checks if the next step button is clicked
  # If it is, it pauses the animation and moves the search one step forward
  def input_right_button
    if right_button_clicked?
      state.play = false
      state.current_step += 1
      move_searches_one_step_forward
    end
  end

  # These methods detect when the buttons are clicked
  def left_button_clicked?
    inputs.mouse.point.inside_rect?(buttons.left) && inputs.mouse.up
  end

  def center_button_clicked?
    inputs.mouse.point.inside_rect?(buttons.center) && inputs.mouse.up
  end

  def right_button_clicked?
    inputs.mouse.point.inside_rect?(buttons.right) && inputs.mouse.up
  end


  # Signal that the user is going to be moving the slider
  # Is the mouse over the circle of the slider?
  def mouse_over_slider?
    circle_x = (slider.x - slider.offset) + (state.current_step * slider.spacing)
    circle_y = (slider.y - slider.offset)
    circle_rect = [circle_x, circle_y, 37, 37]
    inputs.mouse.point.inside_rect?(circle_rect)
  end

  # Signal that the user is going to be moving the star from the first grid
  def bfs_mouse_over_star?
    inputs.mouse.point.inside_rect?(bfs_scale_up(grid.star))
  end

  # Signal that the user is going to be moving the star from the second grid
  def heuristic_mouse_over_star?
    inputs.mouse.point.inside_rect?(heuristic_scale_up(grid.star))
  end

  # Signal that the user is going to be moving the target from the first grid
  def bfs_mouse_over_target?
    inputs.mouse.point.inside_rect?(bfs_scale_up(grid.target))
  end

  # Signal that the user is going to be moving the target from the second grid
  def heuristic_mouse_over_target?
    inputs.mouse.point.inside_rect?(heuristic_scale_up(grid.target))
  end

  # Signal that the user is going to be removing walls from the first grid
  def bfs_mouse_over_wall?
    grid.walls.each_key do |wall|
      return true if inputs.mouse.point.inside_rect?(bfs_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be removing walls from the second grid
  def heuristic_mouse_over_wall?
    grid.walls.each_key do |wall|
      return true if inputs.mouse.point.inside_rect?(heuristic_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be adding walls from the first grid
  def bfs_mouse_over_grid?
    inputs.mouse.point.inside_rect?(bfs_scale_up(grid.rect))
  end

  # Signal that the user is going to be adding walls from the second grid
  def heuristic_mouse_over_grid?
    inputs.mouse.point.inside_rect?(heuristic_scale_up(grid.rect))
  end

  # This method is called when the user is editing the slider
  # It pauses the animation and moves the white circle to the closest integer point
  # on the slider
  # Changes the step of the search to be animated
  def process_input_slider
    state.play = false
    mouse_x = inputs.mouse.point.x

    # Bounds the mouse_x to the closest x value on the slider line
    mouse_x = slider.x if mouse_x < slider.x
    mouse_x = slider.x + slider.w if mouse_x > slider.x + slider.w

    # Sets the current search step to the one represented by the mouse x value
    # The slider's circle moves due to the render_slider method using anim_steps
    state.current_step = ((mouse_x - slider.x) / slider.spacing).to_i

    recalculate_searches
  end

  # Moves the star to the cell closest to the mouse in the first grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def process_input_bfs_star
    old_star = grid.star.clone
    unless bfs_cell_closest_to_mouse == grid.target
      grid.star = bfs_cell_closest_to_mouse
    end
    unless old_star == grid.star
      recalculate_searches
    end
  end

  # Moves the star to the cell closest to the mouse in the second grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def process_input_heuristic_star
    old_star = grid.star.clone
    unless heuristic_cell_closest_to_mouse == grid.target
      grid.star = heuristic_cell_closest_to_mouse
    end
    unless old_star == grid.star
      recalculate_searches
    end
  end

  # Moves the target to the grid closest to the mouse in the first grid
  # Only recalculate_searchess the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def process_input_bfs_target
    old_target = grid.target.clone
    unless bfs_cell_closest_to_mouse == grid.star
      grid.target = bfs_cell_closest_to_mouse
    end
    unless old_target == grid.target
      recalculate_searches
    end
  end

  # Moves the target to the cell closest to the mouse in the second grid
  # Only recalculate_searchess the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def process_input_heuristic_target
    old_target = grid.target.clone
    unless heuristic_cell_closest_to_mouse == grid.star
      grid.target = heuristic_cell_closest_to_mouse
    end
    unless old_target == grid.target
      recalculate_searches
    end
  end

  # Removes walls in the first grid that are under the cursor
  def process_input_bfs_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if bfs_mouse_over_grid?
      if grid.walls.key?(bfs_cell_closest_to_mouse)
        grid.walls.delete(bfs_cell_closest_to_mouse)
        recalculate_searches
      end
    end
  end

  # Removes walls in the second grid that are under the cursor
  def process_input_heuristic_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if heuristic_mouse_over_grid?
      if grid.walls.key?(heuristic_cell_closest_to_mouse)
        grid.walls.delete(heuristic_cell_closest_to_mouse)
        recalculate_searches
      end
    end
  end
  # Adds a wall in the first grid in the cell the mouse is over
  def process_input_bfs_add_wall
    if bfs_mouse_over_grid?
      unless grid.walls.key?(bfs_cell_closest_to_mouse)
        grid.walls[bfs_cell_closest_to_mouse] = true
        recalculate_searches
      end
    end
  end

  # Adds a wall in the second grid in the cell the mouse is over
  def process_input_heuristic_add_wall
    if heuristic_mouse_over_grid?
      unless grid.walls.key?(heuristic_cell_closest_to_mouse)
        grid.walls[heuristic_cell_closest_to_mouse] = true
        recalculate_searches
      end
    end
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse helps with this
  def bfs_cell_closest_to_mouse
    # Closest cell to the mouse in the first grid
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Bound x and y to the grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse in the second grid helps with this
  def heuristic_cell_closest_to_mouse
    # Closest cell grid to the mouse in the second
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Translate the cell to the first grid
    x -= grid.width + 1
    # Bound x and y to the first grid
    x = 0 if x < 0
    y = 0 if y < 0
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  def recalculate_searches
    # Reset the searches
    bfs.came_from    = {}
    bfs.frontier     = []
    bfs.path         = []
    heuristic.came_from = {}
    heuristic.frontier  = []
    heuristic.path      = []

    # Move the searches forward to the current step
    state.current_step.times { move_searches_one_step_forward }
  end

  def move_searches_one_step_forward
    bfs_one_step_forward
    heuristic_one_step_forward
  end

  def bfs_one_step_forward
    return if bfs.came_from.key?(grid.target)

    # Only runs at the beginning of the search as setup.
    if bfs.came_from.empty?
      bfs.frontier << grid.star
      bfs.came_from[grid.star] = nil
    end

    # A step in the search
    unless bfs.frontier.empty?
      # Takes the next frontier cell
      new_frontier = bfs.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless bfs.came_from.key?(neighbor) || grid.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          bfs.frontier << neighbor
          bfs.came_from[neighbor] = new_frontier
        end
      end
    end

    # Sort the frontier so that cells that are in a zigzag pattern are prioritized over those in an line
    # Comment this line and let a path generate to see the difference
    bfs.frontier = bfs.frontier.sort_by { |cell| proximity_to_star(cell) }

    # If the search found the target
    if bfs.came_from.key?(grid.target)
      # Calculate the path between the target and star
      bfs_calc_path
    end
  end

  # Calculates the path between the target and star for the breadth first search
  # Only called when the breadth first search finds the target
  def bfs_calc_path
    # Start from the target
    endpoint = grid.target
    # And the cell it came from
    next_endpoint = bfs.came_from[endpoint]
    while endpoint && next_endpoint
      # Draw a path between these two cells and store it
      path = get_path_between(endpoint, next_endpoint)
      bfs.path << path
      # And get the next pair of cells
      endpoint = next_endpoint
      next_endpoint = bfs.came_from[endpoint]
      # Continue till there are no more cells
    end
  end

  # Moves the heuristic search forward one step
  # Can be called from tick while the animation is playing
  # Can also be called when recalculating the searches after the user edited the grid
  def heuristic_one_step_forward
    # Stop the search if the target has been found
    return if heuristic.came_from.key?(grid.target)

    # If the search has not begun
    if heuristic.came_from.empty?
      # Setup the search to begin from the star
      heuristic.frontier << grid.star
      heuristic.came_from[grid.star] = nil
    end

    # One step in the heuristic search

    # Unless there are no more cells to explore from
    unless heuristic.frontier.empty?
      # Get the next cell to explore from
      new_frontier = heuristic.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless heuristic.came_from.key?(neighbor) || grid.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          heuristic.frontier << neighbor
          heuristic.came_from[neighbor] = new_frontier
        end
      end
    end

    # Sort the frontier so that cells that are in a zigzag pattern are prioritized over those in an line
    heuristic.frontier = heuristic.frontier.sort_by { |cell| proximity_to_star(cell) }
    # Sort the frontier so cells that are close to the target are then prioritized
    heuristic.frontier = heuristic.frontier.sort_by { |cell| heuristic_heuristic(cell) }

    # If the search found the target
    if heuristic.came_from.key?(grid.target)
      # Calculate the path between the target and star
      heuristic_calc_path
    end
  end

  # Returns one-dimensional absolute distance between cell and target
  # Returns a number to compare distances between cells and the target
  def heuristic_heuristic(cell)
    (grid.target.x - cell.x).abs + (grid.target.y - cell.y).abs
  end

  # Calculates the path between the target and star for the heuristic search
  # Only called when the heuristic search finds the target
  def heuristic_calc_path
    # Start from the target
    endpoint = grid.target
    # And the cell it came from
    next_endpoint = heuristic.came_from[endpoint]
    while endpoint && next_endpoint
      # Draw a path between these two cells and store it
      path = get_path_between(endpoint, next_endpoint)
      heuristic.path << path
      # And get the next pair of cells
      endpoint = next_endpoint
      next_endpoint = heuristic.came_from[endpoint]
      # Continue till there are no more cells
    end
  end

  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors(cell)
    neighbors = []

    # Gets all the valid neighbors into the array
    # From southern neighbor, clockwise
    neighbors << [cell.x    , cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y    ] unless cell.x == 0
    neighbors << [cell.x    , cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y    ] unless cell.x == grid.width - 1

    neighbors
  end

  # Finds the vertical and horizontal distance of a cell from the star
  # and returns the larger value
  # This method is used to have a zigzag pattern in the rendered path
  # A cell that is [5, 5] from the star,
  # is explored before over a cell that is [0, 7] away.
  # So, if possible, the search tries to go diagonal (zigzag) first
  def proximity_to_star(cell)
    distance_x = (grid.star.x - cell.x).abs
    distance_y = (grid.star.y - cell.y).abs

    [distance_x, distance_y].max
  end

  # Methods that allow code to be more concise. Subdivides args.state, which is where all variables are stored.
  def grid
    state.grid
  end

  def buttons
    state.buttons
  end

  def slider
    state.slider
  end

  def bfs
    state.bfs
  end

  def heuristic
    state.heuristic
  end

  # Descriptive aliases for colors
  def default_color
    { r: 221, g: 212, b: 213 }
  end

  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  def visited_color
    { r: 204, g: 191, b: 179 }
  end

  def frontier_color
    { r: 103, g: 136, b: 204, a: 200 }
  end

  def path_color
    { r: 231, g: 230, b: 228 }
  end

  def button_color
    [190, 190, 190] # Gray
  end
end
# Method that is called by DragonRuby periodically
# Used for updating animations and calculations
def tick args

  # Pressing r will reset the application
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  # Every tick, new args are passed, and the Breadth First Search tick is called
  $heuristic ||= Heuristic.new
  $heuristic.args = args
  $heuristic.tick
end


def reset
  $heuristic = nil
end

    Heuristic With Walls - main.rb link

    # ./samples/13_path_finding_algorithms/07_heuristic_with_walls/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# This program is inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html

# This time the heuristic search still explored less of the grid, hence finishing faster.
# However, it did not find the shortest path between the star and the target.

# The only difference between this app and Heuristic is the change of the starting position.

class Heuristic_With_Walls
  attr_gtk

  def tick
    defaults
    render
    input
    # If animation is playing, and max steps have not been reached
    # Move the search a step forward
    if state.play && state.current_step < state.max_steps
      # Variable that tells the program what step to recalculate up to
      state.current_step += 1
      move_searches_one_step_forward
    end
  end

  def defaults
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    grid.width     ||= 15
    grid.height    ||= 15
    grid.cell_size ||= 40
    grid.rect      ||= [0, 0, grid.width, grid.height]

    grid.star      ||= [0, 2]
    grid.target    ||= [14, 12]
    grid.walls     ||= {
      [2, 2] => true,
      [3, 2] => true,
      [4, 2] => true,
      [5, 2] => true,
      [6, 2] => true,
      [7, 2] => true,
      [8, 2] => true,
      [9, 2] => true,
      [10, 2] => true,
      [11, 2] => true,
      [12, 2] => true,
      [12, 3] => true,
      [12, 4] => true,
      [12, 5] => true,
      [12, 6] => true,
      [12, 7] => true,
      [12, 8] => true,
      [12, 9] => true,
      [12, 10] => true,
      [12, 11] => true,
      [12, 12] => true,
      [2, 12] => true,
      [3, 12] => true,
      [4, 12] => true,
      [5, 12] => true,
      [6, 12] => true,
      [7, 12] => true,
      [8, 12] => true,
      [9, 12] => true,
      [10, 12] => true,
      [11, 12] => true,
      [12, 12] => true
    }
    # There are no hills in the Heuristic Search Demo

    # What the user is currently editing on the grid
    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    state.user_input ||= :none

    # These variables allow the breadth first search to take place
    # Came_from is a hash with a key of a cell and a value of the cell that was expanded from to find the key.
    # Used to prevent searching cells that have already been found
    # and to trace a path from the target back to the starting point.
    # Frontier is an array of cells to expand the search from.
    # The search is over when there are no more cells to search from.
    # Path stores the path from the target to the star, once the target has been found
    # It prevents calculating the path every tick.
    bfs.came_from  ||= {}
    bfs.frontier   ||= []
    bfs.path       ||= []

    heuristic.came_from ||= {}
    heuristic.frontier  ||= []
    heuristic.path      ||= []

    # Stores which step of the animation is being rendered
    # When the user moves the star or messes with the walls,
    # the searches are recalculated up to this step
    unless state.current_step
      state.current_step = 0
    end

    # At some step the animation will end,
    # and further steps won't change anything (the whole grid will be explored)
    # This step is roughly the grid's width * height
    # When anim_steps equals max_steps no more calculations will occur
    # and the slider will be at the end
    state.max_steps = grid.width * grid.height

    # Whether the animation should play or not
    # If true, every tick moves anim_steps forward one
    # Pressing the stepwise animation buttons will pause the animation
    # An if statement instead of the ||= operator is used for assigning a boolean value.
    # The || operator does not differentiate between nil and false.
    if state.play == nil
      state.play = false
    end

    # Store the rects of the buttons that control the animation
    # They are here for user customization
    # Editing these might require recentering the text inside them
    # Those values can be found in the render_button methods
    buttons.left   = [470, 600, 50, 50]
    buttons.center = [520, 600, 200, 50]
    buttons.right  = [720, 600, 50, 50]

    # The variables below are related to the slider
    # They allow the user to customize them
    # They also give a central location for the render and input methods to get
    # information from
    # x & y are the coordinates of the leftmost part of the slider line
    slider.x = 440
    slider.y = 675
    # This is the width of the line
    slider.w = 360
    # This is the offset for the circle
    # Allows the center of the circle to be on the line,
    # as opposed to the upper right corner
    slider.offset = 20
    # This is the spacing between each of the notches on the slider
    # Notches are places where the circle can rest on the slider line
    # There needs to be a notch for each step before the maximum number of steps
    slider.spacing = slider.w.to_f / state.max_steps.to_f
  end

  # All methods with render draw stuff on the screen
  # UI has buttons, the slider, and labels
  # The search specific rendering occurs in the respective methods
  def render
    render_ui
    render_bfs
    render_heuristic
  end

  def render_ui
    render_buttons
    render_slider
    render_labels
  end

  def render_buttons
    render_left_button
    render_center_button
    render_right_button
  end

  def render_bfs
    render_bfs_grid
    render_bfs_star
    render_bfs_target
    render_bfs_visited
    render_bfs_walls
    render_bfs_frontier
    render_bfs_path
  end

  def render_heuristic
    render_heuristic_grid
    render_heuristic_star
    render_heuristic_target
    render_heuristic_visited
    render_heuristic_walls
    render_heuristic_frontier
    render_heuristic_path
  end

  # This method handles user input every tick
  def input
    # Check and handle button input
    input_buttons

    # If the mouse was lifted this tick
    if inputs.mouse.up
      # Set current input to none
      state.user_input = :none
    end

    # If the mouse was clicked this tick
    if inputs.mouse.down
      # Determine what the user is editing and appropriately edit the state.user_input variable
      determine_input
    end

    # Process user input based on user_input variable and current mouse position
    process_input
  end

  # Determines what the user is editing
  # This method is called when the mouse is clicked down
  def determine_input
    if mouse_over_slider?
      state.user_input = :slider
    # If the mouse is over the star in the first grid
    elsif bfs_mouse_over_star?
      # The user is editing the star from the first grid
      state.user_input = :bfs_star
    # If the mouse is over the star in the second grid
    elsif heuristic_mouse_over_star?
      # The user is editing the star from the second grid
      state.user_input = :heuristic_star
    # If the mouse is over the target in the first grid
    elsif bfs_mouse_over_target?
      # The user is editing the target from the first grid
      state.user_input = :bfs_target
    # If the mouse is over the target in the second grid
    elsif heuristic_mouse_over_target?
      # The user is editing the target from the second grid
      state.user_input = :heuristic_target
    # If the mouse is over a wall in the first grid
    elsif bfs_mouse_over_wall?
      # The user is removing a wall from the first grid
      state.user_input = :bfs_remove_wall
    # If the mouse is over a wall in the second grid
    elsif heuristic_mouse_over_wall?
      # The user is removing a wall from the second grid
      state.user_input = :heuristic_remove_wall
    # If the mouse is over the first grid
    elsif bfs_mouse_over_grid?
      # The user is adding a wall from the first grid
      state.user_input = :bfs_add_wall
    # If the mouse is over the second grid
    elsif heuristic_mouse_over_grid?
      # The user is adding a wall from the second grid
      state.user_input = :heuristic_add_wall
    end
  end

  # Processes click and drag based on what the user is currently dragging
  def process_input
    if state.user_input == :slider
      process_input_slider
    elsif state.user_input == :bfs_star
      process_input_bfs_star
    elsif state.user_input == :heuristic_star
      process_input_heuristic_star
    elsif state.user_input == :bfs_target
      process_input_bfs_target
    elsif state.user_input == :heuristic_target
      process_input_heuristic_target
    elsif state.user_input == :bfs_remove_wall
      process_input_bfs_remove_wall
    elsif state.user_input == :heuristic_remove_wall
      process_input_heuristic_remove_wall
    elsif state.user_input == :bfs_add_wall
      process_input_bfs_add_wall
    elsif state.user_input == :heuristic_add_wall
      process_input_heuristic_add_wall
    end
  end

  def render_slider
    # Using primitives hides the line under the white circle of the slider
    # Draws the line
    outputs.primitives << [slider.x, slider.y, slider.x + slider.w, slider.y].line
    # The circle needs to be offset so that the center of the circle
    # overlaps the line instead of the upper right corner of the circle
    # The circle's x value is also moved based on the current seach step
    circle_x = (slider.x - slider.offset) + (state.current_step * slider.spacing)
    circle_y = (slider.y - slider.offset)
    circle_rect = [circle_x, circle_y, 37, 37]
    outputs.primitives << [circle_rect, 'circle-white.png'].sprite
  end

  def render_labels
    outputs.labels << [205, 625, "Breadth First Search"]
    outputs.labels << [820, 625, "Heuristic Best-First Search"]
  end

  def render_left_button
    # Draws the button_color button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.left, button_color]
    outputs.borders << [buttons.left]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    # If the button size is changed, the label might need to be edited as well
    # to keep the label in the center of the button
    label_x = buttons.left.x + 20
    label_y = buttons.left.y + 35
    outputs.labels  << [label_x, label_y, "<"]
  end

  def render_center_button
    # Draws the button_color button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.center, button_color]
    outputs.borders << [buttons.center]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    # If the button size is changed, the label might need to be edited as well
    # to keep the label in the center of the button
    label_x    = buttons.center.x + 37
    label_y    = buttons.center.y + 35
    label_text = state.play ? "Pause Animation" : "Play Animation"
    outputs.labels << [label_x, label_y, label_text]
  end

  def render_right_button
    # Draws the button_color button, and a black border
    # The border separates the buttons visually
    outputs.solids  << [buttons.right, button_color]
    outputs.borders << [buttons.right]

    # Renders an explanatory label in the center of the button
    # Explains to the user what the button does
    label_x = buttons.right.x + 20
    label_y = buttons.right.y + 35
    outputs.labels  << [label_x, label_y, ">"]
  end

  def render_bfs_grid
    # A large rect the size of the grid
    outputs.solids << bfs_scale_up(grid.rect).merge(default_color)

    outputs.lines << (0..grid.width).map { |x| bfs_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| bfs_horizontal_line(y) }
  end

  def render_heuristic_grid
    # A large rect the size of the grid
    outputs.solids << heuristic_scale_up(grid.rect).merge(default_color)

    outputs.lines << (0..grid.width).map { |x| heuristic_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| heuristic_horizontal_line(y) }
  end

  # Returns a vertical line for a column of the first grid
  def bfs_vertical_line x
    line = { x: x, y: 0, w: 0, h: grid.height }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Returns a horizontal line for a column of the first grid
  def bfs_horizontal_line y
    line = { x: 0, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Returns a vertical line for a column of the second grid
  def heuristic_vertical_line x
    bfs_vertical_line(x + grid.width + 1)
  end

  # Returns a horizontal line for a column of the second grid
  def heuristic_horizontal_line y
    line = { x: grid.width + 1, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Renders the star on the first grid
  def render_bfs_star
    outputs.sprites << bfs_scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the star on the second grid
  def render_heuristic_star
    outputs.sprites << heuristic_scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the target on the first grid
  def render_bfs_target
    outputs.sprites << bfs_scale_up(grid.target).merge({ path: 'target.png' })
  end

  # Renders the target on the second grid
  def render_heuristic_target
    outputs.sprites << heuristic_scale_up(grid.target).merge({ path: 'target.png' })
  end

  # Renders the walls on the first grid
  def render_bfs_walls
    outputs.solids << grid.walls.map do |key, value|
      bfs_scale_up(key).merge(wall_color)
    end
  end

  # Renders the walls on the second grid
  def render_heuristic_walls
    outputs.solids << grid.walls.map do |key, value|
      heuristic_scale_up(key).merge(wall_color)
    end
  end

  # Renders the visited cells on the first grid
  def render_bfs_visited
    outputs.solids << bfs.came_from.map do |key, value|
      bfs_scale_up(key).merge(visited_color)
    end
  end

  # Renders the visited cells on the second grid
  def render_heuristic_visited
    outputs.solids << heuristic.came_from.map do |key, value|
      heuristic_scale_up(key).merge(visited_color)
    end
  end

  # Renders the frontier cells on the first grid
  def render_bfs_frontier
    outputs.solids << bfs.frontier.map do |cell|
      bfs_scale_up(cell).merge(frontier_color)
    end
  end

  # Renders the frontier cells on the second grid
  def render_heuristic_frontier
    outputs.solids << heuristic.frontier.map do |cell|
      heuristic_scale_up(cell).merge(frontier_color)
    end
  end

  # Renders the path found by the breadth first search on the first grid
  def render_bfs_path
    outputs.solids << bfs.path.map do |path|
      bfs_scale_up(path).merge(path_color)
    end
  end

  # Renders the path found by the heuristic search on the second grid
  def render_heuristic_path
    outputs.solids << heuristic.path.map do |path|
      heuristic_scale_up(path).merge(path_color)
    end
  end

  # Returns the rect for the path between two cells based on their relative positions
  def get_path_between(cell_one, cell_two)
    path = nil

    # If cell one is above cell two
    if cell_one.x == cell_two.x && cell_one.y > cell_two.y
      # Path starts from the center of cell two and moves upward to the center of cell one
      path = [cell_two.x + 0.3, cell_two.y + 0.3, 0.4, 1.4]
    # If cell one is below cell two
    elsif cell_one.x == cell_two.x && cell_one.y < cell_two.y
      # Path starts from the center of cell one and moves upward to the center of cell two
      path = [cell_one.x + 0.3, cell_one.y + 0.3, 0.4, 1.4]
    # If cell one is to the left of cell two
    elsif cell_one.x > cell_two.x && cell_one.y == cell_two.y
      # Path starts from the center of cell two and moves rightward to the center of cell one
      path = [cell_two.x + 0.3, cell_two.y + 0.3, 1.4, 0.4]
    # If cell one is to the right of cell two
    elsif cell_one.x < cell_two.x && cell_one.y == cell_two.y
      # Path starts from the center of cell one and moves rightward to the center of cell two
      path = [cell_one.x + 0.3, cell_one.y + 0.3, 1.4, 0.4]
    end

    path
  end

  # In code, the cells are represented as 1x1 rectangles
  # When drawn, the cells are larger than 1x1 rectangles
  # This method is used to scale up cells, and lines
  # Objects are scaled up according to the grid.cell_size variable
  # This allows for easy customization of the visual scale of the grid
  # This method scales up cells for the first grid
  def bfs_scale_up(cell)
    x = cell.x * grid.cell_size
    y = cell.y * grid.cell_size
    w = cell.w.zero? ? grid.cell_size : cell.w * grid.cell_size
    h = cell.h.zero? ? grid.cell_size : cell.h * grid.cell_size
    {x: x, y: y, w: w, h: h}
    # {x:, y:, w:, h:}
  end

  # Translates the given cell grid.width + 1 to the right and then scales up
  # Used to draw cells for the second grid
  # This method does not work for lines,
  # so separate methods exist for the grid lines
  def heuristic_scale_up(cell)
    # Prevents the original value of cell from being edited
    cell = cell.clone
    # Translates the cell to the second grid equivalent
    cell.x += grid.width + 1
    # Proceeds as if scaling up for the first grid
    bfs_scale_up(cell)
  end

  # Checks and handles input for the buttons
  # Called when the mouse is lifted
  def input_buttons
    input_left_button
    input_center_button
    input_right_button
  end

  # Checks if the previous step button is clicked
  # If it is, it pauses the animation and moves the search one step backward
  def input_left_button
    if left_button_clicked?
      state.play = false
      state.current_step -= 1
      recalculate_searches
    end
  end

  # Controls the play/pause button
  # Inverses whether the animation is playing or not when clicked
  def input_center_button
    if center_button_clicked? || inputs.keyboard.key_down.space
      state.play = !state.play
    end
  end

  # Checks if the next step button is clicked
  # If it is, it pauses the animation and moves the search one step forward
  def input_right_button
    if right_button_clicked?
      state.play = false
      state.current_step += 1
      move_searches_one_step_forward
    end
  end

  # These methods detect when the buttons are clicked
  def left_button_clicked?
    inputs.mouse.point.inside_rect?(buttons.left) && inputs.mouse.up
  end

  def center_button_clicked?
    inputs.mouse.point.inside_rect?(buttons.center) && inputs.mouse.up
  end

  def right_button_clicked?
    inputs.mouse.point.inside_rect?(buttons.right) && inputs.mouse.up
  end


  # Signal that the user is going to be moving the slider
  # Is the mouse over the circle of the slider?
  def mouse_over_slider?
    circle_x = (slider.x - slider.offset) + (state.current_step * slider.spacing)
    circle_y = (slider.y - slider.offset)
    circle_rect = [circle_x, circle_y, 37, 37]
    inputs.mouse.point.inside_rect?(circle_rect)
  end

  # Signal that the user is going to be moving the star from the first grid
  def bfs_mouse_over_star?
    inputs.mouse.point.inside_rect?(bfs_scale_up(grid.star))
  end

  # Signal that the user is going to be moving the star from the second grid
  def heuristic_mouse_over_star?
    inputs.mouse.point.inside_rect?(heuristic_scale_up(grid.star))
  end

  # Signal that the user is going to be moving the target from the first grid
  def bfs_mouse_over_target?
    inputs.mouse.point.inside_rect?(bfs_scale_up(grid.target))
  end

  # Signal that the user is going to be moving the target from the second grid
  def heuristic_mouse_over_target?
    inputs.mouse.point.inside_rect?(heuristic_scale_up(grid.target))
  end

  # Signal that the user is going to be removing walls from the first grid
  def bfs_mouse_over_wall?
    grid.walls.each_key do |wall|
      return true if inputs.mouse.point.inside_rect?(bfs_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be removing walls from the second grid
  def heuristic_mouse_over_wall?
    grid.walls.each_key do |wall|
      return true if inputs.mouse.point.inside_rect?(heuristic_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be adding walls from the first grid
  def bfs_mouse_over_grid?
    inputs.mouse.point.inside_rect?(bfs_scale_up(grid.rect))
  end

  # Signal that the user is going to be adding walls from the second grid
  def heuristic_mouse_over_grid?
    inputs.mouse.point.inside_rect?(heuristic_scale_up(grid.rect))
  end

  # This method is called when the user is editing the slider
  # It pauses the animation and moves the white circle to the closest integer point
  # on the slider
  # Changes the step of the search to be animated
  def process_input_slider
    state.play = false
    mouse_x = inputs.mouse.point.x

    # Bounds the mouse_x to the closest x value on the slider line
    mouse_x = slider.x if mouse_x < slider.x
    mouse_x = slider.x + slider.w if mouse_x > slider.x + slider.w

    # Sets the current search step to the one represented by the mouse x value
    # The slider's circle moves due to the render_slider method using anim_steps
    state.current_step = ((mouse_x - slider.x) / slider.spacing).to_i

    recalculate_searches
  end

  # Moves the star to the cell closest to the mouse in the first grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def process_input_bfs_star
    old_star = grid.star.clone
    unless bfs_cell_closest_to_mouse == grid.target
      grid.star = bfs_cell_closest_to_mouse
    end
    unless old_star == grid.star
      recalculate_searches
    end
  end

  # Moves the star to the cell closest to the mouse in the second grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def process_input_heuristic_star
    old_star = grid.star.clone
    unless heuristic_cell_closest_to_mouse == grid.target
      grid.star = heuristic_cell_closest_to_mouse
    end
    unless old_star == grid.star
      recalculate_searches
    end
  end

  # Moves the target to the grid closest to the mouse in the first grid
  # Only recalculate_searchess the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def process_input_bfs_target
    old_target = grid.target.clone
    unless bfs_cell_closest_to_mouse == grid.star
      grid.target = bfs_cell_closest_to_mouse
    end
    unless old_target == grid.target
      recalculate_searches
    end
  end

  # Moves the target to the cell closest to the mouse in the second grid
  # Only recalculate_searchess the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def process_input_heuristic_target
    old_target = grid.target.clone
    unless heuristic_cell_closest_to_mouse == grid.star
      grid.target = heuristic_cell_closest_to_mouse
    end
    unless old_target == grid.target
      recalculate_searches
    end
  end

  # Removes walls in the first grid that are under the cursor
  def process_input_bfs_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if bfs_mouse_over_grid?
      if grid.walls.key?(bfs_cell_closest_to_mouse)
        grid.walls.delete(bfs_cell_closest_to_mouse)
        recalculate_searches
      end
    end
  end

  # Removes walls in the second grid that are under the cursor
  def process_input_heuristic_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if heuristic_mouse_over_grid?
      if grid.walls.key?(heuristic_cell_closest_to_mouse)
        grid.walls.delete(heuristic_cell_closest_to_mouse)
        recalculate_searches
      end
    end
  end
  # Adds a wall in the first grid in the cell the mouse is over
  def process_input_bfs_add_wall
    if bfs_mouse_over_grid?
      unless grid.walls.key?(bfs_cell_closest_to_mouse)
        grid.walls[bfs_cell_closest_to_mouse] = true
        recalculate_searches
      end
    end
  end

  # Adds a wall in the second grid in the cell the mouse is over
  def process_input_heuristic_add_wall
    if heuristic_mouse_over_grid?
      unless grid.walls.key?(heuristic_cell_closest_to_mouse)
        grid.walls[heuristic_cell_closest_to_mouse] = true
        recalculate_searches
      end
    end
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse helps with this
  def bfs_cell_closest_to_mouse
    # Closest cell to the mouse in the first grid
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Bound x and y to the grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse in the second grid helps with this
  def heuristic_cell_closest_to_mouse
    # Closest cell grid to the mouse in the second
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Translate the cell to the first grid
    x -= grid.width + 1
    # Bound x and y to the first grid
    x = 0 if x < 0
    y = 0 if y < 0
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  def recalculate_searches
    # Reset the searches
    bfs.came_from    = {}
    bfs.frontier     = []
    bfs.path         = []
    heuristic.came_from = {}
    heuristic.frontier  = []
    heuristic.path      = []

    # Move the searches forward to the current step
    state.current_step.times { move_searches_one_step_forward }
  end

  def move_searches_one_step_forward
    bfs_one_step_forward
    heuristic_one_step_forward
  end

  def bfs_one_step_forward
    return if bfs.came_from.key?(grid.target)

    # Only runs at the beginning of the search as setup.
    if bfs.came_from.empty?
      bfs.frontier << grid.star
      bfs.came_from[grid.star] = nil
    end

    # A step in the search
    unless bfs.frontier.empty?
      # Takes the next frontier cell
      new_frontier = bfs.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless bfs.came_from.key?(neighbor) || grid.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          bfs.frontier << neighbor
          bfs.came_from[neighbor] = new_frontier
        end
      end
    end

    # Sort the frontier so that cells that are in a zigzag pattern are prioritized over those in an line
    # Comment this line and let a path generate to see the difference
    bfs.frontier = bfs.frontier.sort_by { |cell| proximity_to_star(cell) }

    # If the search found the target
    if bfs.came_from.key?(grid.target)
      # Calculate the path between the target and star
      bfs_calc_path
    end
  end

  # Calculates the path between the target and star for the breadth first search
  # Only called when the breadth first search finds the target
  def bfs_calc_path
    # Start from the target
    endpoint = grid.target
    # And the cell it came from
    next_endpoint = bfs.came_from[endpoint]
    while endpoint && next_endpoint
      # Draw a path between these two cells and store it
      path = get_path_between(endpoint, next_endpoint)
      bfs.path << path
      # And get the next pair of cells
      endpoint = next_endpoint
      next_endpoint = bfs.came_from[endpoint]
      # Continue till there are no more cells
    end
  end

  # Moves the heuristic search forward one step
  # Can be called from tick while the animation is playing
  # Can also be called when recalculating the searches after the user edited the grid
  def heuristic_one_step_forward
    # Stop the search if the target has been found
    return if heuristic.came_from.key?(grid.target)

    # If the search has not begun
    if heuristic.came_from.empty?
      # Setup the search to begin from the star
      heuristic.frontier << grid.star
      heuristic.came_from[grid.star] = nil
    end

    # One step in the heuristic search

    # Unless there are no more cells to explore from
    unless heuristic.frontier.empty?
      # Get the next cell to explore from
      new_frontier = heuristic.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do |neighbor|
        # That have not been visited and are not walls
        unless heuristic.came_from.key?(neighbor) || grid.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          heuristic.frontier << neighbor
          heuristic.came_from[neighbor] = new_frontier
        end
      end
    end

    # Sort the frontier so that cells that are in a zigzag pattern are prioritized over those in an line
    heuristic.frontier = heuristic.frontier.sort_by { |cell| proximity_to_star(cell) }
    # Sort the frontier so cells that are close to the target are then prioritized
    heuristic.frontier = heuristic.frontier.sort_by { |cell| heuristic_heuristic(cell) }

    # If the search found the target
    if heuristic.came_from.key?(grid.target)
      # Calculate the path between the target and star
      heuristic_calc_path
    end
  end

  # Returns one-dimensional absolute distance between cell and target
  # Returns a number to compare distances between cells and the target
  def heuristic_heuristic(cell)
    (grid.target.x - cell.x).abs + (grid.target.y - cell.y).abs
  end

  # Calculates the path between the target and star for the heuristic search
  # Only called when the heuristic search finds the target
  def heuristic_calc_path
    # Start from the target
    endpoint = grid.target
    # And the cell it came from
    next_endpoint = heuristic.came_from[endpoint]
    while endpoint && next_endpoint
      # Draw a path between these two cells and store it
      path = get_path_between(endpoint, next_endpoint)
      heuristic.path << path
      # And get the next pair of cells
      endpoint = next_endpoint
      next_endpoint = heuristic.came_from[endpoint]
      # Continue till there are no more cells
    end
  end

  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors(cell)
    neighbors = []

    # Gets all the valid neighbors into the array
    # From southern neighbor, clockwise
    neighbors << [cell.x    , cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y    ] unless cell.x == 0
    neighbors << [cell.x    , cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y    ] unless cell.x == grid.width - 1

    neighbors
  end

  # Finds the vertical and horizontal distance of a cell from the star
  # and returns the larger value
  # This method is used to have a zigzag pattern in the rendered path
  # A cell that is [5, 5] from the star,
  # is explored before over a cell that is [0, 7] away.
  # So, if possible, the search tries to go diagonal (zigzag) first
  def proximity_to_star(cell)
    distance_x = (grid.star.x - cell.x).abs
    distance_y = (grid.star.y - cell.y).abs

    [distance_x, distance_y].max
  end

  # Methods that allow code to be more concise. Subdivides args.state, which is where all variables are stored.
  def grid
    state.grid
  end

  def buttons
    state.buttons
  end

  def slider
    state.slider
  end

  def bfs
    state.bfs
  end

  def heuristic
    state.heuristic
  end

  # Descriptive aliases for colors
  def default_color
    { r: 221, g: 212, b: 213 }
  end

  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  def visited_color
    { r: 204, g: 191, b: 179 }
  end

  def frontier_color
    { r: 103, g: 136, b: 204, a: 200 }
  end

  def path_color
    { r: 231, g: 230, b: 228 }
  end

  def button_color
    [190, 190, 190] # Gray
  end
end
# Method that is called by DragonRuby periodically
# Used for updating animations and calculations
def tick args

  # Pressing r will reset the application
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  # Every tick, new args are passed, and the Breadth First Search tick is called
  $heuristic_with_walls ||= Heuristic_With_Walls.new
  $heuristic_with_walls.args = args
  $heuristic_with_walls.tick
end


def reset
  $heuristic_with_walls = nil
end

    A Star - main.rb link

    # ./samples/13_path_finding_algorithms/08_a_star/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# This program is inspired by https://www.redblobgames.com/pathfinding/a-star/introduction.html

# The A* Search works by incorporating both the distance from the starting point
# and the distance from the target in its heurisitic.

# It tends to find the correct (shortest) path even when the Greedy Best-First Search does not,
# and it explores less of the grid, and is therefore faster, than Dijkstra's Search.

class A_Star_Algorithm
  attr_gtk

  def tick
    defaults
    render
    input

    if dijkstra.came_from.empty?
      calc_searches
    end
  end

  def defaults
    # Variables to edit the size and appearance of the grid
    # Freely customizable to user's liking
    grid.width     ||= 15
    grid.height    ||= 15
    grid.cell_size ||= 27
    grid.rect      ||= [0, 0, grid.width, grid.height]

    grid.star      ||= [0, 2]
    grid.target    ||= [11, 13]
    grid.walls     ||= {
      [2, 2] => true,
      [3, 2] => true,
      [4, 2] => true,
      [5, 2] => true,
      [6, 2] => true,
      [7, 2] => true,
      [8, 2] => true,
      [9, 2] => true,
      [10, 2] => true,
      [11, 2] => true,
      [12, 2] => true,
      [12, 3] => true,
      [12, 4] => true,
      [12, 5] => true,
      [12, 6] => true,
      [12, 7] => true,
      [12, 8] => true,
      [12, 9] => true,
      [12, 10] => true,
      [12, 11] => true,
      [12, 12] => true,
      [5, 12] => true,
      [6, 12] => true,
      [7, 12] => true,
      [8, 12] => true,
      [9, 12] => true,
      [10, 12] => true,
      [11, 12] => true,
      [12, 12] => true
    }

    # What the user is currently editing on the grid
    # We store this value, because we want to remember the value even when
    # the user's cursor is no longer over what they're interacting with, but
    # they are still clicking down on the mouse.
    state.user_input ||= :none

    # These variables allow the breadth first search to take place
    # Came_from is a hash with a key of a cell and a value of the cell that was expanded from to find the key.
    # Used to prevent searching cells that have already been found
    # and to trace a path from the target back to the starting point.
    # Frontier is an array of cells to expand the search from.
    # The search is over when there are no more cells to search from.
    # Path stores the path from the target to the star, once the target has been found
    # It prevents calculating the path every tick.
    dijkstra.came_from   ||= {}
    dijkstra.cost_so_far ||= {}
    dijkstra.frontier    ||= []
    dijkstra.path        ||= []

    greedy.came_from ||= {}
    greedy.frontier  ||= []
    greedy.path      ||= []

    a_star.frontier    ||= []
    a_star.came_from   ||= {}
    a_star.path        ||= []
    a_star.cost_so_far ||= {}
  end

  # All methods with render draw stuff on the screen
  # UI has buttons, the slider, and labels
  # The search specific rendering occurs in the respective methods
  def render
    render_labels
    render_dijkstra
    render_greedy
    render_a_star
  end

  def render_labels
    outputs.labels << [150, 450, "Dijkstra's"]
    outputs.labels << [550, 450, "Greedy Best-First"]
    outputs.labels << [1025, 450, "A* Search"]
  end

  def render_dijkstra
    render_dijkstra_grid
    render_dijkstra_star
    render_dijkstra_target
    render_dijkstra_visited
    render_dijkstra_walls
    render_dijkstra_path
  end

  def render_greedy
    render_greedy_grid
    render_greedy_star
    render_greedy_target
    render_greedy_visited
    render_greedy_walls
    render_greedy_path
  end

  def render_a_star
    render_a_star_grid
    render_a_star_star
    render_a_star_target
    render_a_star_visited
    render_a_star_walls
    render_a_star_path
  end

  # This method handles user input every tick
  def input
    # If the mouse was lifted this tick
    if inputs.mouse.up
      # Set current input to none
      state.user_input = :none
    end

    # If the mouse was clicked this tick
    if inputs.mouse.down
      # Determine what the user is editing and appropriately edit the state.user_input variable
      determine_input
    end

    # Process user input based on user_input variable and current mouse position
    process_input
  end

  # Determines what the user is editing
  # This method is called when the mouse is clicked down
  def determine_input
    # If the mouse is over the star in the first grid
    if dijkstra_mouse_over_star?
      # The user is editing the star from the first grid
      state.user_input = :dijkstra_star
    # If the mouse is over the star in the second grid
    elsif greedy_mouse_over_star?
      # The user is editing the star from the second grid
      state.user_input = :greedy_star
    # If the mouse is over the star in the third grid
    elsif a_star_mouse_over_star?
      # The user is editing the star from the third grid
      state.user_input = :a_star_star
    # If the mouse is over the target in the first grid
    elsif dijkstra_mouse_over_target?
      # The user is editing the target from the first grid
      state.user_input = :dijkstra_target
    # If the mouse is over the target in the second grid
    elsif greedy_mouse_over_target?
      # The user is editing the target from the second grid
      state.user_input = :greedy_target
    # If the mouse is over the target in the third grid
    elsif a_star_mouse_over_target?
      # The user is editing the target from the third grid
      state.user_input = :a_star_target
    # If the mouse is over a wall in the first grid
    elsif dijkstra_mouse_over_wall?
      # The user is removing a wall from the first grid
      state.user_input = :dijkstra_remove_wall
    # If the mouse is over a wall in the second grid
    elsif greedy_mouse_over_wall?
      # The user is removing a wall from the second grid
      state.user_input = :greedy_remove_wall
    # If the mouse is over a wall in the third grid
    elsif a_star_mouse_over_wall?
      # The user is removing a wall from the third grid
      state.user_input = :a_star_remove_wall
    # If the mouse is over the first grid
    elsif dijkstra_mouse_over_grid?
      # The user is adding a wall from the first grid
      state.user_input = :dijkstra_add_wall
    # If the mouse is over the second grid
    elsif greedy_mouse_over_grid?
      # The user is adding a wall from the second grid
      state.user_input = :greedy_add_wall
    # If the mouse is over the third grid
    elsif a_star_mouse_over_grid?
      # The user is adding a wall from the third grid
      state.user_input = :a_star_add_wall
    end
  end

  # Processes click and drag based on what the user is currently dragging
  def process_input
    if state.user_input == :dijkstra_star
      process_input_dijkstra_star
    elsif state.user_input == :greedy_star
      process_input_greedy_star
    elsif state.user_input == :a_star_star
      process_input_a_star_star
    elsif state.user_input == :dijkstra_target
      process_input_dijkstra_target
    elsif state.user_input == :greedy_target
      process_input_greedy_target
    elsif state.user_input == :a_star_target
      process_input_a_star_target
    elsif state.user_input == :dijkstra_remove_wall
      process_input_dijkstra_remove_wall
    elsif state.user_input == :greedy_remove_wall
      process_input_greedy_remove_wall
    elsif state.user_input == :a_star_remove_wall
      process_input_a_star_remove_wall
    elsif state.user_input == :dijkstra_add_wall
      process_input_dijkstra_add_wall
    elsif state.user_input == :greedy_add_wall
      process_input_greedy_add_wall
    elsif state.user_input == :a_star_add_wall
      process_input_a_star_add_wall
    end
  end

  def render_dijkstra_grid
    # A large rect the size of the grid
    outputs.solids << dijkstra_scale_up(grid.rect).merge(default_color)

    outputs.lines << (0..grid.width).map { |x| dijkstra_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| dijkstra_horizontal_line(y) }
  end

  def render_greedy_grid
    # A large rect the size of the grid
    outputs.solids << greedy_scale_up(grid.rect).merge(default_color)

    outputs.lines << (0..grid.width).map { |x| greedy_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| greedy_horizontal_line(y) }
  end

  def render_a_star_grid
    # A large rect the size of the grid
    outputs.solids << a_star_scale_up(grid.rect).merge(default_color)

    outputs.lines << (0..grid.width).map { |x| a_star_vertical_line(x) }
    outputs.lines << (0..grid.height).map { |y| a_star_horizontal_line(y) }
  end

  # Returns a vertical line for a column of the first grid
  def dijkstra_vertical_line x
    line = { x: x, y: 0, w: 0, h: grid.height }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Returns a horizontal line for a column of the first grid
  def dijkstra_horizontal_line y
    line = { x: 0, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Returns a vertical line for a column of the second grid
  def greedy_vertical_line x
    dijkstra_vertical_line(x + grid.width + 1)
  end

  # Returns a horizontal line for a column of the second grid
  def greedy_horizontal_line y
    line = { x: grid.width + 1, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Returns a vertical line for a column of the third grid
  def a_star_vertical_line x
    dijkstra_vertical_line(x + grid.width + 1 + grid.width + 1)
  end

  # Returns a horizontal line for a column of the third grid
  def a_star_horizontal_line y
    line = { x: grid.width + 1 + grid.width + 1, y: y, w: grid.width, h: 0 }
    line.transform_values { |v| v * grid.cell_size }
  end

  # Renders the star on the first grid
  def render_dijkstra_star
    outputs.sprites << dijkstra_scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the star on the second grid
  def render_greedy_star
    outputs.sprites << greedy_scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the star on the third grid
  def render_a_star_star
    outputs.sprites << a_star_scale_up(grid.star).merge({ path: 'star.png' })
  end

  # Renders the target on the first grid
  def render_dijkstra_target
    outputs.sprites << dijkstra_scale_up(grid.target).merge({ path: 'target.png' })
  end

  # Renders the target on the second grid
  def render_greedy_target
    outputs.sprites << greedy_scale_up(grid.target).merge({ path: 'target.png' })
  end

  # Renders the target on the third grid
  def render_a_star_target
    outputs.sprites << a_star_scale_up(grid.target).merge({ path: 'target.png' })
  end

  # Renders the walls on the first grid
  def render_dijkstra_walls
    outputs.solids << grid.walls.map do |key, value|
      dijkstra_scale_up(key).merge(wall_color)
    end
  end

  # Renders the walls on the second grid
  def render_greedy_walls
    outputs.solids << grid.walls.map do |key, value|
      greedy_scale_up(key).merge(wall_color)
    end
  end

  # Renders the walls on the third grid
  def render_a_star_walls
    outputs.solids << grid.walls.map do |key, value|
      a_star_scale_up(key).merge(wall_color)
    end
  end

  # Renders the visited cells on the first grid
  def render_dijkstra_visited
    outputs.solids << dijkstra.came_from.map do |key, value|
      dijkstra_scale_up(key).merge(visited_color)
    end
  end

  # Renders the visited cells on the second grid
  def render_greedy_visited
    outputs.solids << greedy.came_from.map do |key, value|
      greedy_scale_up(key).merge(visited_color)
    end
  end

  # Renders the visited cells on the third grid
  def render_a_star_visited
    outputs.solids << a_star.came_from.map do |key, value|
      a_star_scale_up(key).merge(visited_color)
    end
  end

  # Renders the path found by the breadth first search on the first grid
  def render_dijkstra_path
    outputs.solids << dijkstra.path.map do |path|
      dijkstra_scale_up(path).merge(path_color)
    end
  end

  # Renders the path found by the greedy search on the second grid
  def render_greedy_path
    outputs.solids << greedy.path.map do |path|
      greedy_scale_up(path).merge(path_color)
    end
  end

  # Renders the path found by the a_star search on the third grid
  def render_a_star_path
    outputs.solids << a_star.path.map do |path|
      a_star_scale_up(path).merge(path_color)
    end
  end

  # Returns the rect for the path between two cells based on their relative positions
  def get_path_between(cell_one, cell_two)
    path = []

    # If cell one is above cell two
    if cell_one.x == cell_two.x && cell_one.y > cell_two.y
      # Path starts from the center of cell two and moves upward to the center of cell one
      path = [cell_two.x + 0.3, cell_two.y + 0.3, 0.4, 1.4]
    # If cell one is below cell two
    elsif cell_one.x == cell_two.x && cell_one.y < cell_two.y
      # Path starts from the center of cell one and moves upward to the center of cell two
      path = [cell_one.x + 0.3, cell_one.y + 0.3, 0.4, 1.4]
    # If cell one is to the left of cell two
    elsif cell_one.x > cell_two.x && cell_one.y == cell_two.y
      # Path starts from the center of cell two and moves rightward to the center of cell one
      path = [cell_two.x + 0.3, cell_two.y + 0.3, 1.4, 0.4]
    # If cell one is to the right of cell two
    elsif cell_one.x < cell_two.x && cell_one.y == cell_two.y
      # Path starts from the center of cell one and moves rightward to the center of cell two
      path = [cell_one.x + 0.3, cell_one.y + 0.3, 1.4, 0.4]
    end

    path
  end

  # In code, the cells are represented as 1x1 rectangles
  # When drawn, the cells are larger than 1x1 rectangles
  # This method is used to scale up cells, and lines
  # Objects are scaled up according to the grid.cell_size variable
  # This allows for easy customization of the visual scale of the grid
  # This method scales up cells for the first grid
  def dijkstra_scale_up(cell)
    x = cell.x * grid.cell_size
    y = cell.y * grid.cell_size
    w = cell.w.zero? ? grid.cell_size : cell.w * grid.cell_size
    h = cell.h.zero? ? grid.cell_size : cell.h * grid.cell_size
    {x: x, y: y, w: w, h: h}
  end

  # Translates the given cell grid.width + 1 to the right and then scales up
  # Used to draw cells for the second grid
  # This method does not work for lines,
  # so separate methods exist for the grid lines
  def greedy_scale_up(cell)
    # Prevents the original value of cell from being edited
    cell = cell.clone
    # Translates the cell to the second grid equivalent
    cell.x += grid.width + 1
    # Proceeds as if scaling up for the first grid
    dijkstra_scale_up(cell)
  end

  # Translates the given cell (grid.width + 1) * 2 to the right and then scales up
  # Used to draw cells for the third grid
  # This method does not work for lines,
  # so separate methods exist for the grid lines
  def a_star_scale_up(cell)
    # Prevents the original value of cell from being edited
    cell = cell.clone
    # Translates the cell to the second grid equivalent
    cell.x += grid.width + 1
    # Translates the cell to the third grid equivalent
    cell.x += grid.width + 1
    # Proceeds as if scaling up for the first grid
    dijkstra_scale_up(cell)
  end

  # Signal that the user is going to be moving the star from the first grid
  def dijkstra_mouse_over_star?
    inputs.mouse.point.inside_rect?(dijkstra_scale_up(grid.star))
  end

  # Signal that the user is going to be moving the star from the second grid
  def greedy_mouse_over_star?
    inputs.mouse.point.inside_rect?(greedy_scale_up(grid.star))
  end

  # Signal that the user is going to be moving the star from the third grid
  def a_star_mouse_over_star?
    inputs.mouse.point.inside_rect?(a_star_scale_up(grid.star))
  end

  # Signal that the user is going to be moving the target from the first grid
  def dijkstra_mouse_over_target?
    inputs.mouse.point.inside_rect?(dijkstra_scale_up(grid.target))
  end

  # Signal that the user is going to be moving the target from the second grid
  def greedy_mouse_over_target?
    inputs.mouse.point.inside_rect?(greedy_scale_up(grid.target))
  end

  # Signal that the user is going to be moving the target from the third grid
  def a_star_mouse_over_target?
    inputs.mouse.point.inside_rect?(a_star_scale_up(grid.target))
  end

  # Signal that the user is going to be removing walls from the first grid
  def dijkstra_mouse_over_wall?
    grid.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(dijkstra_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be removing walls from the second grid
  def greedy_mouse_over_wall?
    grid.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(greedy_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be removing walls from the third grid
  def a_star_mouse_over_wall?
    grid.walls.each_key do | wall |
      return true if inputs.mouse.point.inside_rect?(a_star_scale_up(wall))
    end

    false
  end

  # Signal that the user is going to be adding walls from the first grid
  def dijkstra_mouse_over_grid?
    inputs.mouse.point.inside_rect?(dijkstra_scale_up(grid.rect))
  end

  # Signal that the user is going to be adding walls from the second grid
  def greedy_mouse_over_grid?
    inputs.mouse.point.inside_rect?(greedy_scale_up(grid.rect))
  end

  # Signal that the user is going to be adding walls from the third grid
  def a_star_mouse_over_grid?
    inputs.mouse.point.inside_rect?(a_star_scale_up(grid.rect))
  end

  # Moves the star to the cell closest to the mouse in the first grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def process_input_dijkstra_star
    old_star = grid.star.clone
    unless dijkstra_cell_closest_to_mouse == grid.target
      grid.star = dijkstra_cell_closest_to_mouse
    end
    unless old_star == grid.star
      reset_searches
    end
  end

  # Moves the star to the cell closest to the mouse in the second grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def process_input_greedy_star
    old_star = grid.star.clone
    unless greedy_cell_closest_to_mouse == grid.target
      grid.star = greedy_cell_closest_to_mouse
    end
    unless old_star == grid.star
      reset_searches
    end
  end

  # Moves the star to the cell closest to the mouse in the third grid
  # Only resets the search if the star changes position
  # Called whenever the user is editing the star (puts mouse down on star)
  def process_input_a_star_star
    old_star = grid.star.clone
    unless a_star_cell_closest_to_mouse == grid.target
      grid.star = a_star_cell_closest_to_mouse
    end
    unless old_star == grid.star
      reset_searches
    end
  end

  # Moves the target to the grid closest to the mouse in the first grid
  # Only reset_searchess the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def process_input_dijkstra_target
    old_target = grid.target.clone
    unless dijkstra_cell_closest_to_mouse == grid.star
      grid.target = dijkstra_cell_closest_to_mouse
    end
    unless old_target == grid.target
      reset_searches
    end
  end

  # Moves the target to the cell closest to the mouse in the second grid
  # Only reset_searchess the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def process_input_greedy_target
    old_target = grid.target.clone
    unless greedy_cell_closest_to_mouse == grid.star
      grid.target = greedy_cell_closest_to_mouse
    end
    unless old_target == grid.target
      reset_searches
    end
  end

  # Moves the target to the cell closest to the mouse in the third grid
  # Only reset_searchess the search if the target changes position
  # Called whenever the user is editing the target (puts mouse down on target)
  def process_input_a_star_target
    old_target = grid.target.clone
    unless a_star_cell_closest_to_mouse == grid.star
      grid.target = a_star_cell_closest_to_mouse
    end
    unless old_target == grid.target
      reset_searches
    end
  end

  # Removes walls in the first grid that are under the cursor
  def process_input_dijkstra_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if dijkstra_mouse_over_grid?
      if grid.walls.has_key?(dijkstra_cell_closest_to_mouse)
        grid.walls.delete(dijkstra_cell_closest_to_mouse)
        reset_searches
      end
    end
  end

  # Removes walls in the second grid that are under the cursor
  def process_input_greedy_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if greedy_mouse_over_grid?
      if grid.walls.key?(greedy_cell_closest_to_mouse)
        grid.walls.delete(greedy_cell_closest_to_mouse)
        reset_searches
      end
    end
  end

  # Removes walls in the third grid that are under the cursor
  def process_input_a_star_remove_wall
    # The mouse needs to be inside the grid, because we only want to remove walls
    # the cursor is directly over
    # Recalculations should only occur when a wall is actually deleted
    if a_star_mouse_over_grid?
      if grid.walls.key?(a_star_cell_closest_to_mouse)
        grid.walls.delete(a_star_cell_closest_to_mouse)
        reset_searches
      end
    end
  end

  # Adds a wall in the first grid in the cell the mouse is over
  def process_input_dijkstra_add_wall
    if dijkstra_mouse_over_grid?
      unless grid.walls.key?(dijkstra_cell_closest_to_mouse)
        grid.walls[dijkstra_cell_closest_to_mouse] = true
        reset_searches
      end
    end
  end

  # Adds a wall in the second grid in the cell the mouse is over
  def process_input_greedy_add_wall
    if greedy_mouse_over_grid?
      unless grid.walls.key?(greedy_cell_closest_to_mouse)
        grid.walls[greedy_cell_closest_to_mouse] = true
        reset_searches
      end
    end
  end

  # Adds a wall in the third grid in the cell the mouse is over
  def process_input_a_star_add_wall
    if a_star_mouse_over_grid?
      unless grid.walls.key?(a_star_cell_closest_to_mouse)
        grid.walls[a_star_cell_closest_to_mouse] = true
        reset_searches
      end
    end
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse helps with this
  def dijkstra_cell_closest_to_mouse
    # Closest cell to the mouse in the first grid
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Bound x and y to the grid
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse in the second grid helps with this
  def greedy_cell_closest_to_mouse
    # Closest cell grid to the mouse in the second
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Translate the cell to the first grid
    x -= grid.width + 1
    # Bound x and y to the first grid
    x = 0 if x < 0
    y = 0 if y < 0
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  # When the user grabs the star and puts their cursor to the far right
  # and moves up and down, the star is supposed to move along the grid as well
  # Finding the cell closest to the mouse in the third grid helps with this
  def a_star_cell_closest_to_mouse
    # Closest cell grid to the mouse in the second
    x = (inputs.mouse.point.x / grid.cell_size).to_i
    y = (inputs.mouse.point.y / grid.cell_size).to_i
    # Translate the cell to the first grid
    x -= (grid.width + 1) * 2
    # Bound x and y to the first grid
    x = 0 if x < 0
    y = 0 if y < 0
    x = grid.width - 1 if x > grid.width - 1
    y = grid.height - 1 if y > grid.height - 1
    # Return closest cell
    [x, y]
  end

  def reset_searches
    # Reset the searches
    dijkstra.came_from      = {}
    dijkstra.cost_so_far    = {}
    dijkstra.frontier       = []
    dijkstra.path           = []

    greedy.came_from = {}
    greedy.frontier  = []
    greedy.path      = []
    a_star.came_from = {}
    a_star.frontier  = []
    a_star.path      = []
  end

  def calc_searches
    calc_dijkstra
    calc_greedy
    calc_a_star
    # Move the searches forward to the current step
    # state.current_step.times { move_searches_one_step_forward }
  end

  def calc_dijkstra
    # Sets up the search to begin from the star
    dijkstra.frontier << grid.star
    dijkstra.came_from[grid.star] = nil
    dijkstra.cost_so_far[grid.star] = 0

    # Until the target is found or there are no more cells to explore from
    until dijkstra.came_from.key?(grid.target) or dijkstra.frontier.empty?
      # Take the next frontier cell. The first element is the cell, the second is the priority.
      new_frontier = dijkstra.frontier.shift#[0]
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do | neighbor |
        # That have not been visited and are not walls
        unless dijkstra.came_from.key?(neighbor) or grid.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          dijkstra.frontier << neighbor
          dijkstra.came_from[neighbor] = new_frontier
          dijkstra.cost_so_far[neighbor] = dijkstra.cost_so_far[new_frontier] + 1
        end
      end

      # Sort the frontier so that cells that are in a zigzag pattern are prioritized over those in an line
      # Comment this line and let a path generate to see the difference
      dijkstra.frontier = dijkstra.frontier.sort_by {| cell | proximity_to_star(cell) }
      dijkstra.frontier = dijkstra.frontier.sort_by {| cell | dijkstra.cost_so_far[cell] }
    end


    # If the search found the target
    if dijkstra.came_from.key?(grid.target)
      # Calculate the path between the target and star
      dijkstra_calc_path
    end
  end

  def calc_greedy
    # Sets up the search to begin from the star
    greedy.frontier << grid.star
    greedy.came_from[grid.star] = nil

    # Until the target is found or there are no more cells to explore from
    until greedy.came_from.key?(grid.target) or greedy.frontier.empty?
      # Take the next frontier cell
      new_frontier = greedy.frontier.shift
      # For each of its neighbors
      adjacent_neighbors(new_frontier).each do | neighbor |
        # That have not been visited and are not walls
        unless greedy.came_from.key?(neighbor) or grid.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          greedy.frontier << neighbor
          greedy.came_from[neighbor] = new_frontier
        end
      end
      # Sort the frontier so that cells that are in a zigzag pattern are prioritized over those in an line
      # Comment this line and let a path generate to see the difference
      greedy.frontier = greedy.frontier.sort_by {| cell | proximity_to_star(cell) }
      # Sort the frontier so cells that are close to the target are then prioritized
      greedy.frontier = greedy.frontier.sort_by {| cell | greedy_heuristic(cell)  }
    end


    # If the search found the target
    if greedy.came_from.key?(grid.target)
      # Calculate the path between the target and star
      greedy_calc_path
    end
  end

  def calc_a_star
    # Setup the search to start from the star
    a_star.came_from[grid.star] = nil
    a_star.cost_so_far[grid.star] = 0
    a_star.frontier << grid.star

    # Until there are no more cells to explore from or the search has found the target
    until a_star.frontier.empty? or a_star.came_from.key?(grid.target)
      # Get the next cell to expand from
      current_frontier = a_star.frontier.shift

      # For each of that cells neighbors
      adjacent_neighbors(current_frontier).each do | neighbor |
        # That have not been visited and are not walls
        unless a_star.came_from.key?(neighbor) or grid.walls.key?(neighbor)
          # Add them to the frontier and mark them as visited
          a_star.frontier << neighbor
          a_star.came_from[neighbor] = current_frontier
          a_star.cost_so_far[neighbor] = a_star.cost_so_far[current_frontier] + 1
        end
      end

      # Sort the frontier so that cells that are in a zigzag pattern are prioritized over those in an line
      # Comment this line and let a path generate to see the difference
      a_star.frontier = a_star.frontier.sort_by {| cell | proximity_to_star(cell) }
      a_star.frontier = a_star.frontier.sort_by {| cell | a_star.cost_so_far[cell] + greedy_heuristic(cell) }
    end

    # If the search found the target
    if a_star.came_from.key?(grid.target)
      # Calculate the path between the target and star
      a_star_calc_path
    end
  end

  # Calculates the path between the target and star for the breadth first search
  # Only called when the breadth first search finds the target
  def dijkstra_calc_path
    # Start from the target
    endpoint = grid.target
    # And the cell it came from
    next_endpoint = dijkstra.came_from[endpoint]
    while endpoint && next_endpoint
      # Draw a path between these two cells and store it
      path = get_path_between(endpoint, next_endpoint)
      dijkstra.path << path
      # And get the next pair of cells
      endpoint = next_endpoint
      next_endpoint = dijkstra.came_from[endpoint]
      # Continue till there are no more cells
    end
  end

  # Returns one-dimensional absolute distance between cell and target
  # Returns a number to compare distances between cells and the target
  def greedy_heuristic(cell)
    (grid.target.x - cell.x).abs + (grid.target.y - cell.y).abs
  end

  # Calculates the path between the target and star for the greedy search
  # Only called when the greedy search finds the target
  def greedy_calc_path
    # Start from the target
    endpoint = grid.target
    # And the cell it came from
    next_endpoint = greedy.came_from[endpoint]
    while endpoint && next_endpoint
      # Draw a path between these two cells and store it
      path = get_path_between(endpoint, next_endpoint)
      greedy.path << path
      # And get the next pair of cells
      endpoint = next_endpoint
      next_endpoint = greedy.came_from[endpoint]
      # Continue till there are no more cells
    end
  end

  # Calculates the path between the target and star for the a_star search
  # Only called when the a_star search finds the target
  def a_star_calc_path
    # Start from the target
    endpoint = grid.target
    # And the cell it came from
    next_endpoint = a_star.came_from[endpoint]

    while endpoint && next_endpoint
      # Draw a path between these two cells and store it
      path = get_path_between(endpoint, next_endpoint)
      a_star.path << path
      # And get the next pair of cells
      endpoint = next_endpoint
      next_endpoint = a_star.came_from[endpoint]
      # Continue till there are no more cells
    end
  end

  # Returns a list of adjacent cells
  # Used to determine what the next cells to be added to the frontier are
  def adjacent_neighbors(cell)
    neighbors = []

    # Gets all the valid neighbors into the array
    # From southern neighbor, clockwise
    neighbors << [cell.x    , cell.y - 1] unless cell.y == 0
    neighbors << [cell.x - 1, cell.y    ] unless cell.x == 0
    neighbors << [cell.x    , cell.y + 1] unless cell.y == grid.height - 1
    neighbors << [cell.x + 1, cell.y    ] unless cell.x == grid.width - 1

    neighbors
  end

  # Finds the vertical and horizontal distance of a cell from the star
  # and returns the larger value
  # This method is used to have a zigzag pattern in the rendered path
  # A cell that is [5, 5] from the star,
  # is explored before over a cell that is [0, 7] away.
  # So, if possible, the search tries to go diagonal (zigzag) first
  def proximity_to_star(cell)
    distance_x = (grid.star.x - cell.x).abs
    distance_y = (grid.star.y - cell.y).abs

    if distance_x > distance_y
      return distance_x
    else
      return distance_y
    end
  end

  # Methods that allow code to be more concise. Subdivides args.state, which is where all variables are stored.
  def grid
    state.grid
  end

  def dijkstra
    state.dijkstra
  end

  def greedy
    state.greedy
  end

  def a_star
    state.a_star
  end

  # Descriptive aliases for colors
  def default_color
    { r: 221, g: 212, b: 213 }
  end

  def wall_color
    { r: 134, g: 134, b: 120 }
  end

  def visited_color
    { r: 204, g: 191, b: 179 }
  end

  def path_color
    { r: 231, g: 230, b: 228 }
  end

  def button_color
    [190, 190, 190] # Gray
  end
end


# Method that is called by DragonRuby periodically
# Used for updating animations and calculations
def tick args

  # Pressing r will reset the application
  if args.inputs.keyboard.key_down.r
    args.gtk.reset
    reset
    return
  end

  # Every tick, new args are passed, and the Breadth First Search tick is called
  $a_star_algorithm ||= A_Star_Algorithm.new
  $a_star_algorithm.args = args
  $a_star_algorithm.tick
end


def reset
  $a_star_algorithm = nil
end

    Tower Defense - main.rb link

    # ./samples/13_path_finding_algorithms/09_tower_defense/app/main.rb
# Contributors outside of DragonRuby who also hold Copyright:
# - Sujay Vadlakonda: https://github.com/sujayvadlakonda

# An example of some major components in a tower defence game
# The pathing of the tanks is determined by A* algorithm -- try editing the walls

# The turrets shoot bullets at the closest tank. The bullets are heat-seeking

def tick args
  $gtk.reset if args.inputs.keyboard.key_down.r
  defaults args
  render args
  calc args
end

def defaults args
  args.outputs.background_color = wall_color
  args.state.grid_size = 5
  args.state.tile_size = 50
  args.state.grid_start ||= [0, 0]
  args.state.grid_goal  ||= [4, 4]

  # Try editing these walls to see the path change!
  args.state.walls ||= {
    [0, 4] => true,
    [1, 3] => true,
    [3, 1] => true,
    # [4, 0] => true,
  }

  args.state.a_star.frontier ||= []
  args.state.a_star.came_from ||= {}
  args.state.a_star.path ||= []

  args.state.tanks ||= []
  args.state.tank_spawn_period ||= 60
  args.state.tank_sprite_path ||= 'sprites/circle/white.png'
  args.state.tank_speed ||= 1

  args.state.turret_shoot_period = 10
  # Turrets can be entered as [x, y] but are immediately mapped to hashes
  # Walls are also added where the turrets are to prevent tanks from pathing over them
  args.state.turrets ||= [
    [2, 2]
  ].each { |turret| args.state.walls[turret] = true}.map do |x, y|
    {
      x: x * args.state.tile_size,
      y: y * args.state.tile_size,
      w: args.state.tile_size,
      h: args.state.tile_size,
      path: 'sprites/circle/gray.png',
      range: 100
    }
  end

  args.state.bullet_size ||= 25
  args.state.bullets ||= []
  args.state.bullet_path ||= 'sprites/circle/orange.png'
end

def render args
  render_grid args
  render_a_star args
  args.outputs.sprites << args.state.tanks
  args.outputs.sprites << args.state.turrets
  args.outputs.sprites << args.state.bullets
end

def render_grid args
  # Draw a square the size and color of the grid
  args.outputs.solids << {
    x: 0,
    y: 0,
    w: args.state.grid_size * args.state.tile_size,
    h: args.state.grid_size * args.state.tile_size,
  }.merge(grid_color)

  # Draw lines across the grid to show tiles
  (args.state.grid_size + 1).times do | value |
    render_horizontal_line(args, value)
    render_vertical_line(args, value)
  end

  # Render special tiles
  render_tile(args, args.state.grid_start, start_color)
  render_tile(args, args.state.grid_goal, goal_color)
  args.state.walls.keys.each { |wall| render_tile(args, wall, wall_color) }
end

def render_vertical_line args, x
  args.outputs.lines << {
    x: x * args.state.tile_size,
    y: 0,
    w: 0,
    h: args.state.grid_size * args.state.tile_size
  }
end

def render_horizontal_line args, y
  args.outputs.lines << {
    x: 0,
    y: y * args.state.tile_size,
    w: args.state.grid_size * args.state.tile_size,
    h: 0
  }
end

def render_tile args, tile, color
  args.outputs.solids << {
    x: tile.x * args.state.tile_size,
    y: tile.y * args.state.tile_size,
    w: args.state.tile_size,
    h: args.state.tile_size,
    r: color[0],
    g: color[1],
    b: color[2]
  }
end

def calc args
  calc_a_star args
  calc_tanks args
  calc_turrets args
  calc_bullets args
end

def calc_a_star args
  # Only does this one time
  return unless args.state.a_star.path.empty?

  # Start the search from the grid start
  args.state.a_star.frontier << args.state.grid_start
  args.state.a_star.came_from[args.state.grid_start] = nil

  # Until a path to the goal has been found or there are no more tiles to explore
  until (args.state.a_star.came_from.key?(args.state.grid_goal) || args.state.a_star.frontier.empty?)
    # For the first tile in the frontier
    tile_to_expand_from = args.state.a_star.frontier.shift
    # Add each of its neighbors to the frontier
    neighbors(args, tile_to_expand_from).each do |tile|
      args.state.a_star.frontier << tile
      args.state.a_star.came_from[tile] = tile_to_expand_from
    end
  end

  # Stop calculating a path if the goal was never reached
  return unless args.state.a_star.came_from.key? args.state.grid_goal

  # Fill path by tracing back from the goal
  current_cell = args.state.grid_goal
  while current_cell
    args.state.a_star.path.unshift current_cell
    current_cell = args.state.a_star.came_from[current_cell]
  end

  puts "The path has been calculated"
  puts args.state.a_star.path
end

def calc_tanks args
  spawn_tank args
  move_tanks args
end

def move_tanks args
  # Remove tanks that have reached the end of their path
  args.state.tanks.reject! { |tank| tank[:a_star].empty? }

  # Tanks have an array that has each tile it has to go to in order from a* path
  args.state.tanks.each do | tank |
    destination = tank[:a_star][0]
    # Move the tank towards the destination
    tank[:x] += copy_sign(args.state.tank_speed, ((destination.x * args.state.tile_size) - tank[:x]))
    tank[:y] += copy_sign(args.state.tank_speed, ((destination.y * args.state.tile_size) - tank[:y]))
    # If the tank has reached its destination
    if (destination.x * args.state.tile_size) == tank[:x] &&
        (destination.y * args.state.tile_size) == tank[:y]
      # Set the destination to the next point in the path
      tank[:a_star].shift
    end
  end
end

def calc_turrets args
  return unless args.state.tick_count.mod_zero? args.state.turret_shoot_period
  args.state.turrets.each do | turret |
    # Finds the closest tank
    target = nil
    shortest_distance = turret[:range] + 1
    args.state.tanks.each do | tank |
      distance = distance_between(turret[:x], turret[:y], tank[:x], tank[:y])
      if distance < shortest_distance
        target = tank
        shortest_distance = distance
      end
    end
    # If there is a tank in range, fires a bullet
    if target
      args.state.bullets << {
        x: turret[:x],
        y: turret[:y],
        w: args.state.bullet_size,
        h: args.state.bullet_size,
        path: args.state.bullet_path,
        # Note that this makes it heat-seeking, because target is passed by reference
        # Could do target.clone to make the bullet go to where the tank initially was
        target: target
      }
    end
  end
end

def calc_bullets args
  # Bullets aim for the center of their targets
  args.state.bullets.each { |bullet| move bullet, center_of(bullet[:target])}
  args.state.bullets.reject! { |b| b.intersect_rect? b[:target] }
end

def center_of object
  object = object.clone
  object[:x] += 0.5
  object[:y] += 0.5
  object
end

def render_a_star args
  args.state.a_star.path.map do |tile|
    # Map each x, y coordinate to the center of the tile and scale up
    [(tile.x + 0.5) * args.state.tile_size, (tile.y + 0.5) * args.state.tile_size]
  end.inject do | point_a,  point_b |
    # Render the line between each point
    args.outputs.lines << [point_a.x, point_a.y, point_b.x, point_b.y, a_star_color]
    point_b
  end
end

# Moves object to target at speed
def move object, target, speed = 1
  if target.is_a? Hash
    object[:x] += copy_sign(speed, target[:x] - object[:x])
    object[:y] += copy_sign(speed, target[:y] - object[:y])
  else
    object[:x] += copy_sign(speed, target.x - object[:x])
    object[:y] += copy_sign(speed, target.y - object[:y])
  end
end


def distance_between a_x, a_y, b_x, b_y
  (((b_x - a_x) ** 2) + ((b_y - a_y) ** 2)) ** 0.5
end

def copy_sign value, sign
  return 0 if sign == 0
  return value if sign > 0
  -value
end

def spawn_tank args
  return unless args.state.tick_count.mod_zero? args.state.tank_spawn_period
  args.state.tanks << {
    x: args.state.grid_start.x,
    y: args.state.grid_start.y,
    w: args.state.tile_size,
    h: args.state.tile_size,
    path: args.state.tank_sprite_path,
    a_star: args.state.a_star.path.clone
  }
end

def neighbors args, tile
  [[tile.x, tile.y - 1],
   [tile.x, tile.y + 1],
   [tile.x + 1, tile.y],
   [tile.x - 1, tile.y]].reject do |neighbor|
    args.state.a_star.came_from.key?(neighbor) || tile_out_of_bounds?(args, neighbor) ||
      args.state.walls.key?(neighbor)
  end
end

def tile_out_of_bounds? args, tile
  tile.x < 0 || tile.y < 0 || tile.x >= args.state.grid_size || tile.y >= args.state.grid_size
end

def grid_color
  { r: 133, g: 226, b: 144 }
end

def start_color
  [226, 144, 133]
end

def goal_color
  [226, 133, 144]
end

def wall_color
  [133, 144, 226]
end

def a_star_color
  [0, 0, 255]
end

    Vr link

    Skybox - main.rb link

    # ./samples/14_vr/01_skybox/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  tick_game args
end

    Skybox - tick.rb link

    # ./samples/14_vr/01_skybox/app/tick.rb
def skybox args, x, y, z, size
  sprite = { a: 80, path: 'sprites/box.png' }

  front      = { x: x, y: y, z: z, w: size, h: size, **sprite }
  front_720  = { x: x, y: y, z: z + 1, w: size, h: size * 9.fdiv(16), **sprite }
  back       = { x: x, y: y, z: z + size, w: size, h: size, **sprite }
  bottom     = { x: x, y: y - size.half, z: z + size.half, w: size, h: size, angle_x: 90, **sprite }
  top        = { x: x, y: y + size.half, z: z + size.half, w: size, h: size, angle_x: 90, **sprite }
  left       = { x: x - size.half, y: y, w: size, h: size, z: z + size.half, angle_y: 90, **sprite }
  right      = { x: x + size.half, y: y, w: size, h: size, z: z + size.half, angle_y: 90, **sprite }

  args.outputs.sprites << [back,
                           left,
                           top,
                           bottom,
                           right,
                           front,
                           front_720]
end

def tick_game args
  args.outputs.background_color = [0, 0, 0]

  args.state.z     ||= 0
  args.state.scale ||= 0.05

  if args.inputs.controller_one.key_down.a
    if args.grid.name == :bottom_left
      args.grid.origin_center!
    else
      args.grid.origin_bottom_left!
    end
  end

  args.state.scale += args.inputs.controller_one.right_analog_x_perc * 0.01
  args.state.z -= args.inputs.controller_one.right_analog_y_perc * 1.5

  args.state.scale = args.state.scale.clamp(0.05, 1.0)
  args.state.z = 0    if args.state.z < 0
  args.state.z = 1280 if args.state.z > 1280

  skybox args, 0, 0, args.state.z, 1280 * args.state.scale

  render_guides args
end

def render_guides args
  label_style = { alignment_enum: 1,
                  size_enum: -2,
                  vertical_alignment_enum: 0, r: 255, g: 255, b: 255 }

  instructions = [
    "controller position: #{args.inputs.controller_one.left_hand.x} #{args.inputs.controller_one.left_hand.y} #{args.inputs.controller_one.left_hand.z}",
    "scale: #{args.state.scale.to_sf} (right analog left/right)",
    "z: #{args.state.z.to_sf} (right analog up/down)",
    "origin: :#{args.grid.name} (A button)",
  ]

  args.outputs.labels << instructions.map_with_index do |text, i|
    { x: 640,
      y: 100 + ((instructions.length - (i + 3)) * 22),
      z: args.state.z + 2,
      a: 255,
      text: text,
      ** label_style,
      alignment_enum: 1,
      vertical_alignment_enum: 0 }
  end

  # lines for scaled box
  size      = 1280 * args.state.scale
  size_16_9 = size * 9.fdiv(16)

  args.outputs.primitives << [
    { x: size - 1280, y: size,        z:            0, w: 1280 * 2, r: 128, g: 128, b: 128, a:  64 }.line!,
    { x: size - 1280, y: size,        z: args.state.z + 2, w: 1280 * 2, r: 128, g: 128, b: 128, a: 255 }.line!,

    { x: size - 1280, y: size_16_9,   z:            0, w: 1280 * 2, r: 128, g: 128, b: 128, a:  64 }.line!,
    { x: size - 1280, y: size_16_9,   z: args.state.z + 2, w: 1280 * 2, r: 128, g: 128, b: 128, a: 255 }.line!,

    { x: size,        y: size - 1280, z:            0, h: 1280 * 2, r: 128, g: 128, b: 128, a:  64 }.line!,
    { x: size,        y: size - 1280, z: args.state.z + 2, h: 1280 * 2, r: 128, g: 128, b: 128, a: 255 }.line!,

    { x: size,        y: size,        z: args.state.z + 3, size_enum: -2,
      vertical_alignment_enum: 0,
      text: "#{size.to_sf}, #{size.to_sf}, #{args.state.z.to_sf}",
      r: 255, g: 255, b: 255, a: 255 }.label!,

    { x: size,        y: size_16_9,   z: args.state.z + 3, size_enum: -2,
      vertical_alignment_enum: 0,
      text: "#{size.to_sf}, #{size_16_9.to_sf}, #{args.state.z.to_sf}",
      r: 255, g: 255, b: 255, a: 255 }.label!,
  ]

  xs = [
    { description: "left",   x:    0, alignment_enum: 0 },
    { description: "center", x:  640, alignment_enum: 1 },
    { description: "right",  x: 1280, alignment_enum: 2 },
  ]

  ys = [
    { description: "bottom",        y:    0, vertical_alignment_enum: 0 },
    { description: "center",        y:  640, vertical_alignment_enum: 1 },
    { description: "center (720p)", y:  360, vertical_alignment_enum: 1 },
    { description: "top",           y: 1280, vertical_alignment_enum: 2 },
    { description: "top (720p)",    y:  720, vertical_alignment_enum: 2 },
  ]

  args.outputs.primitives << xs.product(ys).map do |(xdef, ydef)|
    [
      { x: xdef.x,
        y: ydef.y,
        z: args.state.z + 3,
        text: "#{xdef.x.to_sf}, #{ydef.y.to_sf} #{args.state.z.to_sf}",
        **label_style,
        alignment_enum: xdef.alignment_enum,
        vertical_alignment_enum: ydef.vertical_alignment_enum
      },
      { x: xdef.x,
        y: ydef.y - 20,
        z: args.state.z + 3,
        text: "#{ydef.description}, #{xdef.description}",
        **label_style,
        alignment_enum: xdef.alignment_enum,
        vertical_alignment_enum: ydef.vertical_alignment_enum
      }
    ]
  end

  args.outputs.primitives << xs.product(ys).map do |(xdef, ydef)|
    [
      {
        x: xdef.x - 1280,
        y: ydef.y,
        w: 1280 * 2,
        a: 64,
        r: 128, g: 128, b: 128
      }.line!,
      {
        x: xdef.x,
        y: ydef.y - 720,
        h: 720 * 2,
        a: 64,
        r: 128, g: 128, b: 128
      }.line!,
    ].map do |p|
      [
        p.merge(z:            0, a:  64),
        p.merge(z: args.state.z + 2, a: 255)
      ]
    end
  end
end

$gtk.reset

    Top Down Rpg - main.rb link

    # ./samples/14_vr/02_top_down_rpg/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  tick_game args
end

    Top Down Rpg - tick.rb link

    # ./samples/14_vr/02_top_down_rpg/app/tick.rb
class Game
  attr_gtk

  def tick
    outputs.background_color = [0, 0, 0]
    args.state.tile_size     = 80
    args.state.player_speed  = 4
    args.state.player      ||= tile(args, 7, 3, 0, 128, 180)
    generate_map args

    # adds walls, goal, and player to args.outputs.solids so they appear on screen
    args.outputs.solids << args.state.goal
    args.outputs.solids << args.state.walls
    args.outputs.solids << args.state.player

    args.outputs.solids << args.state.walls.map { |s| s.to_hash.merge(z: 2, g: 80) }
    args.outputs.solids << args.state.walls.map { |s| s.to_hash.merge(z: 10, g: 255, a: 50) }

    # if player's box intersects with goal, a label is output onto the screen
    if args.state.player.intersect_rect? args.state.goal
      args.outputs.labels << { x: 640,
                               y: 360,
                               z: 10,
                               text: "YOU'RE A GOD DAMN WIZARD, HARRY.",
                               size_enum: 10,
                               alignment_enum: 1,
                               vertical_alignment_enum: 1,
                               r: 255,
                               g: 255,
                               b: 255 }
    end

    move_player args, -1,  0 if args.inputs.keyboard.left  || args.inputs.controller_one.left # x position decreases by 1 if left key is pressed
    move_player args,  1,  0 if args.inputs.keyboard.right || args.inputs.controller_one.right # x position increases by 1 if right key is pressed
    move_player args,  0, -1 if args.inputs.keyboard.up    || args.inputs.controller_one.down # y position increases by 1 if up is pressed
    move_player args,  0,  1 if args.inputs.keyboard.down  || args.inputs.controller_one.up # y position decreases by 1 if down is pressed
  end

  # Sets position, size, and color of the tile
  def tile args, x, y, *color
    [x * args.state.tile_size, # sets definition for array using method parameters
     y * args.state.tile_size, # multiplying by tile_size sets x and y to correct position using pixel values
     args.state.tile_size,
     args.state.tile_size,
     *color]
  end

  # Creates map by adding tiles to the wall, as well as a goal (that the player needs to reach)
  def generate_map args
    return if args.state.area

    # Creates the area of the map. There are 9 rows running horizontally across the screen
    # and 16 columns running vertically on the screen. Any spot with a "1" is not
    # open for the player to move into (and is green), and any spot with a "0" is available
    # for the player to move in.
    args.state.area = [
      [1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
      [1, 1, 1, 2, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1,], # the "2" represents the goal
      [1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
      [1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
      [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,],
      [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,],
      [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,],
      [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,],
      [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 ],
    ].reverse # reverses the order of the area collection

    # By reversing the order, the way that the area appears above is how it appears
    # on the screen in the game. If we did not reverse, the map would appear inverted.

    #The wall starts off with no tiles.
    args.state.walls = []

    # If v is 1, a green tile is added to args.state.walls.
    # If v is 2, a black tile is created as the goal.
    args.state.area.map_2d do |y, x, v|
      if    v == 1
        args.state.walls << tile(args, x, y, 0, 255, 0) # green tile
      elsif v == 2 # notice there is only one "2" above because there is only one single goal
        args.state.goal   = tile(args, x, y, 180,  0, 0) # black tile
      end
    end
  end

  # Allows the player to move their box around the screen
  def move_player args, *vector
    box = args.state.player.shift_rect(vector) # box is able to move at an angle

    # If the player's box hits a wall, it is not able to move further in that direction
    return if args.state.walls
                .any_intersect_rect?(box)

    # Player's box is able to move at angles (not just the four general directions) fast
    args.state.player =
      args.state.player
        .shift_rect(vector.x * args.state.player_speed, # if we don't multiply by speed, then
                    vector.y * args.state.player_speed) # the box will move extremely slow
  end
end

$game = Game.new

def tick_game args
  $game.args = args
  $game.tick
end

$gtk.reset

    Space Invaders - main.rb link

    # ./samples/14_vr/03_space_invaders/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  tick_game args
end

    Space Invaders - tick.rb link

    # ./samples/14_vr/03_space_invaders/app/tick.rb
class Game
  attr_gtk

  def tick
    grid.origin_center!
    defaults
    outputs.background_color = [0, 0, 0]
    args.outputs.sprites << state.enemies.map { |e| enemy_prefab e }.to_a
  end

  def defaults
    state.enemy_sprite_size = 64
    state.row_size = 16
    state.max_rows = 20
    state.enemies ||= 32.map_with_index do |i|
      x = i % 16
      y = i.idiv 16
      { row: y, col: x }
    end
  end

  def enemy_prefab enemy
    if enemy.row > state.max_rows
      raise "#{enemy}"
    end
    relative_row = enemy.row + 1
    z = 50 - relative_row * 10
    x = (enemy.col * state.enemy_sprite_size) - (state.enemy_sprite_size * state.row_size).idiv(2)
    enemy_sprite(x, enemy.row * 10 + 100, z * 10, enemy)
  end

  def enemy_sprite x, y, z, meta
    index = 0.frame_index count: 2, hold_for: 50, repeat: true
    { x: x,
      y: y,
      z: z,
      w: state.enemy_sprite_size,
      h: state.enemy_sprite_size,
      path: 'sprites/enemy.png',
      source_x: 128 * index,
      source_y: 0,
      source_w: 128,
      source_h: 128,
      meta: meta }
  end
end

$game = Game.new

def tick_game args
  $game.args = args
  $game.tick
end

$gtk.reset

    Let There Be Light - main.rb link

    # ./samples/14_vr/04_let_there_be_light/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  tick_game args
end

    Let There Be Light - tick.rb link

    # ./samples/14_vr/04_let_there_be_light/app/tick.rb
class Game
  attr_gtk

  def tick
    grid.origin_center!
    defaults
    state.angle_shift_x ||= 180
    state.angle_shift_y ||= 180

    if inputs.controller_one.right_analog_y_perc.round(2) != 0.00
      args.state.star_distance += (inputs.controller_one.right_analog_y_perc * 0.25) ** 2 * inputs.controller_one.right_analog_y_perc.sign
      state.star_distance = state.star_distance.clamp(state.min_star_distance, state.max_star_distance)
      state.star_sprites = calc_star_primitives
    elsif inputs.controller_one.down
      args.state.star_distance += (1.0 * 0.25) ** 2
      state.star_distance = state.star_distance.clamp(state.min_star_distance, state.max_star_distance)
      state.star_sprites = calc_star_primitives
    elsif inputs.controller_one.up
      args.state.star_distance -= (1.0 * 0.25) ** 2
      state.star_distance = state.star_distance.clamp(state.min_star_distance, state.max_star_distance)
      state.star_sprites = calc_star_primitives
    end

    render
  end

  def calc_star_primitives
    args.state.stars.map do |s|
      w = (32 * state.star_distance).clamp(1, 32)
      h = (32 * state.star_distance).clamp(1, 32)
      x = (state.max.x * state.star_distance) * s.xr
      y = (state.max.y * state.star_distance) * s.yr
      z = state.center.z + (state.max.z * state.star_distance * 10 * s.zr)

      angle_x = Math.atan2(z - 600, y).to_degrees + 90
      angle_y = Math.atan2(z - 600, x).to_degrees + 90

      draw_x = x - w.half
      draw_y = y - 40 - h.half
      draw_z = z

      { x: draw_x,
        y: draw_y,
        z: draw_z,
        b: 255,
        w: w,
        h: h,
        angle_x: angle_x,
        angle_y: angle_y,
        path: 'sprites/star.png' }
    end
  end

  def render
    outputs.background_color = [0, 0, 0]
    if state.star_distance <= 1.0
      text_alpha = (1 - state.star_distance) * 255
      args.outputs.labels << { x: 0, y: 50, text: "Let there be light.", r: 255, g: 255, b: 255, size_enum: 1, alignment_enum: 1, a: text_alpha }
      args.outputs.labels << { x: 0, y: 25, text: "(right analog: up/down)", r: 255, g: 255, b: 255, size_enum: -2, alignment_enum: 1, a: text_alpha }
    end

    args.outputs.sprites << state.star_sprites
  end

  def random_point
    r = { xr: 2.randomize(:ratio) - 1,
          yr: 2.randomize(:ratio) - 1,
          zr: 2.randomize(:ratio) - 1 }
    if (r.xr ** 2 + r.yr ** 2 + r.zr ** 2) > 1.0
      return random_point
    else
      return r
    end
  end

  def defaults
    state.max_star_distance ||= 100
    state.min_star_distance ||= 0.001
    state.star_distance     ||= 0.001
    state.star_angle        ||= 0

    state.center.x       ||= 0
    state.center.y       ||= 0
    state.center.z       ||= 30
    state.max.x          ||= 640
    state.max.y          ||= 640
    state.max.z          ||= 50

    state.stars ||= 1500.map do
      random_point
    end

    state.star_sprites ||= calc_star_primitives
  end
end

$game = Game.new

def tick_game args
  $game.args = args
  $game.tick
end

$gtk.reset

    Draw A Cube - main.rb link

    # ./samples/14_vr/05_draw_a_cube/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  tick_game args
end

    Draw A Cube - tick.rb link

    # ./samples/14_vr/05_draw_a_cube/app/tick.rb
def cube args, x, y, z, size
  sprite = { w: size, h: size, path: 'sprites/square/blue.png', a: 80 }
  back   = { x: x,                 y: y,                 z: z - size.half + 1,              **sprite }
  front  = { x: x,                 y: y,                 z: z + size.half - 1,              **sprite }
  top    = { x: x,                 y: y + size.half - 1, z: z,                 angle_x: 90, **sprite }
  bottom = { x: x,                 y: y - size.half + 1, z: z,                 angle_x: 90, **sprite }
  left   = { x: x - size.half + 1, y: y,                 z: z,                 angle_y: 90, **sprite }
  right  = { x: x + size.half - 1, y: y,                 z: z,                 angle_y: 90, **sprite }

  args.outputs.sprites << [back, left, top, bottom, right, front]
end

def tick_game args
  args.grid.origin_center!
  args.outputs.background_color = [0, 0, 0]

  args.state.x ||= 0
  args.state.y ||= 0

  args.state.x += 10 * args.inputs.controller_one.right_analog_x_perc
  args.state.y += 10 * args.inputs.controller_one.right_analog_y_perc

  cube args, args.state.x, args.state.y, 0, 100
end

    Draw A Cube With Triangles - main.rb link

    # ./samples/14_vr/05_draw_a_cube_with_triangles/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  tick_game args
end

    Draw A Cube With Triangles - tick.rb link

    # ./samples/14_vr/05_draw_a_cube_with_triangles/app/tick.rb
include MatrixFunctions

def tick args
  args.grid.origin_center!

  # model A
  args.state.a = [
    [vec4(0, 0, 0, 1),   vec4(0.1, 0, 0, 1),   vec4(0, 0.1, 0, 1)],
    [vec4(0.1, 0, 0, 1), vec4(0.1, 0.1, 0, 1), vec4(0, 0.1, 0, 1)]
  ]

  # model to world
  args.state.back = mul_triangles args,
                                  args.state.a,
                                  (translate -0.05, -0.05, 0),
                                  (translate 0, 0, -0.05),
                                  (rotate_x args.state.tick_count),
                                  (rotate_y args.state.tick_count),
                                  (rotate_z args.state.tick_count)

  args.state.front = mul_triangles args,
                                   args.state.a,
                                   (translate -0.05, -0.05, 0),
                                   (translate 0, 0, 0.05),
                                   (rotate_x args.state.tick_count),
                                   (rotate_y args.state.tick_count),
                                   (rotate_z args.state.tick_count)

  args.state.left = mul_triangles args,
                                  args.state.a,
                                  (translate -0.05, -0.05, 0),
                                  (rotate_y 90),
                                  (translate -0.05, 0, 0),
                                  (rotate_x args.state.tick_count),
                                  (rotate_y args.state.tick_count),
                                  (rotate_z args.state.tick_count)

  args.state.right = mul_triangles args,
                                   args.state.a,
                                   (translate -0.05, -0.05, 0),
                                   (rotate_y 90),
                                   (translate  0.05, 0, 0),
                                   (rotate_x args.state.tick_count),
                                   (rotate_y args.state.tick_count),
                                   (rotate_z args.state.tick_count)

  args.state.top = mul_triangles args,
                                 args.state.a,
                                 (translate -0.05, -0.05, 0),
                                 (rotate_x 90),
                                 (translate 0, 0.05, 0),
                                 (rotate_x args.state.tick_count),
                                 (rotate_y args.state.tick_count),
                                 (rotate_z args.state.tick_count)

  args.state.bottom = mul_triangles args,
                                    args.state.a,
                                    (translate -0.05, -0.05, 0),
                                    (rotate_x 90),
                                    (translate 0, -0.05, 0),
                                    (rotate_x args.state.tick_count),
                                    (rotate_y args.state.tick_count),
                                    (rotate_z args.state.tick_count)

  render_square args, args.state.back
  render_square args, args.state.front
  render_square args, args.state.left
  render_square args, args.state.right
  render_square args, args.state.top
  render_square args, args.state.bottom
end

def render_square args, triangles
  args.outputs.sprites << { x:  triangles[0][0].x * 1280,
                            y:  triangles[0][0].y * 1280,
                            z:  triangles[0][0].z * 1280,
                            x2: triangles[0][1].x * 1280,
                            y2: triangles[0][1].y * 1280,
                            z2: triangles[0][1].z * 1280,
                            x3: triangles[0][2].x * 1280,
                            y3: triangles[0][2].y * 1280,
                            z3: triangles[0][2].z * 1280,
                            a: 255,
                            source_x:   0,
                            source_y:   0,
                            source_x2: 80,
                            source_y2:  0,
                            source_x3:  0,
                            source_y3: 80,
                            path: 'sprites/square/red.png' }

  args.outputs.sprites << { x:  triangles[1][0].x * 1280,
                            y:  triangles[1][0].y * 1280,
                            z:  triangles[1][0].z * 1280,
                            x2: triangles[1][1].x * 1280,
                            y2: triangles[1][1].y * 1280,
                            z2: triangles[1][1].z * 1280,
                            x3: triangles[1][2].x * 1280,
                            y3: triangles[1][2].y * 1280,
                            z3: triangles[1][2].z * 1280,
                            a: 255,
                            source_x:  80,
                            source_y:   0,
                            source_x2: 80,
                            source_y2: 80,
                            source_x3:  0,
                            source_y3: 80,
                            path: 'sprites/square/red.png' }
end

def mul_triangles args, triangles, *mul_def
  triangles.map do |vecs|
    vecs.map do |vec|
      mul vec, *mul_def
    end
  end
end

def scale scale
  mat4 scale,     0,     0,   0,
           0, scale,     0,   0,
           0,     0, scale,   0,
           0,     0,     0,   1
end

def rotate_y angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  mat4  cos_t,  0, sin_t, 0,
        0,      1, 0,     0,
        -sin_t, 0, cos_t, 0,
        0,      0, 0,     1
end

def rotate_z angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  mat4 cos_t, -sin_t, 0, 0,
       sin_t,  cos_t, 0, 0,
       0,      0,     1, 0,
       0,      0,     0, 1
end

def translate dx, dy, dz
  mat4 1, 0, 0, dx,
       0, 1, 0, dy,
       0, 0, 1, dz,
       0, 0, 0,  1
end


def rotate_x angle_d
  cos_t = Math.cos angle_d.to_radians
  sin_t = Math.sin angle_d.to_radians
  mat4  1,     0,      0, 0,
        0, cos_t, -sin_t, 0,
        0, sin_t,  cos_t, 0,
        0,     0,      0, 1
end

    Gimbal Lock - main.rb link

    # ./samples/14_vr/05_gimbal_lock/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  $game ||= Game.new
  $game.args = args
  $game.tick
end

    Gimbal Lock - tick.rb link

    # ./samples/14_vr/05_gimbal_lock/app/tick.rb
class Game
  attr_gtk

  def tick
    grid.origin_center!
    state.angle_x ||= 0
    state.angle_y ||= 0
    state.angle_z ||= 0

    if inputs.left
      state.angle_z += 1
    elsif inputs.right
      state.angle_z -= 1
    end

    if inputs.up
      state.angle_x += 1
    elsif inputs.down
      state.angle_x -= 1
    end

    if inputs.controller_one.a
      state.angle_y += 1
    elsif inputs.controller_one.b
      state.angle_y -= 1
    end

    outputs.sprites << {
      x: 0,
      y: 0,
      w: 100,
      h: 100,
      path: 'sprites/square/blue.png',
      angle_x: state.angle_x,
      angle_y: state.angle_y,
      angle: state.angle_z,
    }
  end
end

    Citadels - main.rb link

    # ./samples/14_vr/06_citadels/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  $game ||= Game.new
  $game.args = args
  $game.tick
end

    Citadels - tick.rb link

    # ./samples/14_vr/06_citadels/app/tick.rb
class Game
  attr_gtk

  def citadel x, y, z
    angle = state.tick_count.idiv(10) % 360
    adjacent = 40
    adjacent = adjacent.ceil
    angle = Math.atan2(40, 70).to_degrees
    y += 500
    x -= 40
    back_sprites = [
      { z: z - 40 + adjacent.half,
        x: x,
        y: y + 75,
        w: 80, h: 80, angle_x: angle, path: "sprites/triangle/equilateral/blue.png" },
      { z: z - 40,
        x: x,
        y: y - 400 + 80,
        w: 80, h: 400, path: "sprites/square/blue.png" },
    ]

    left_sprites = [
      { z: z,
        x: x - 40 + adjacent.half,
        y: y + 75,
        w: 80, h: 80, angle_x: -angle, angle_y: 90, path: "sprites/triangle/equilateral/blue.png" },
      { z: z,                      x: x - 40,
        y: y - 400 + 80,
        w: 80, h: 400, angle_y: 90, path: "sprites/square/blue.png" },
    ]

    right_sprites = [
      { z: z,
        x: x + 40 - adjacent.half,
        y: y + 75,
        w: 80, h: 80, angle_x: angle, angle_y: 90, path: "sprites/triangle/equilateral/blue.png" },
      { z: z,
        x: x + 40,
        y: y - 400 + 80,
        w: 80, h: 400, angle_y: 90, path: "sprites/square/blue.png" },
    ]

    front_sprites = [
      { z: z + 40 - adjacent.half,
        x: x,
        y: y + 75,
        w: 80, h: 80, angle_x: -angle, path: "sprites/triangle/equilateral/blue.png" },
      { z: z + 40,
        x: x,
        y: y - 400 + 80,
        w: 80, h: 400, path: "sprites/square/blue.png" },
    ]

    if x > 700
      [
        back_sprites,
        right_sprites,
        front_sprites,
        left_sprites,
      ]
    elsif x < 600
      [
        back_sprites,
        left_sprites,
        front_sprites,
        right_sprites,
      ]
    else
      [
        back_sprites,
        left_sprites,
        right_sprites,
        front_sprites,
      ]
    end

  end

  def tick
    state.z ||= 200
    state.z += inputs.controller_one.right_analog_y_perc
    state.columns ||= 100.map do
      {
        x: rand(12) * 400,
        y: 0,
        z: rand(12) * 400,
      }
    end

    outputs.sprites << state.columns.map do |col|
      citadel(col.x - 640, col.y - 400, state.z - col.z)
    end
  end
end

$game = Game.new

def tick_game args
  $game.args = args
  $game.tick
end

$gtk.reset

    Flappy credits.txt link

    # ./samples/14_vr/07_flappy_vr/CREDITS.txt
code: Amir Rajan, https://twitter.com/amirrajan
graphics and audio: Nick Culbertson, https://twitter.com/MobyPixel

    Flappy main.rb link

    # ./samples/14_vr/07_flappy_vr/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  tick_game args
end

    Flappy tick.rb link

    # ./samples/14_vr/07_flappy_vr/app/tick.rb
class FlappyDragon
  attr_accessor :grid, :inputs, :state, :outputs

  def background_z
    -640
  end

  def flappy_sprite_z
    -120
  end

  def game_text_z
    0
  end

  def menu_overlay_z
    10
  end

  def menu_text_z
    menu_overlay_z + 1
  end

  def flash_z
    1
  end

  def tick
    defaults
    render
    calc
    process_inputs
  end

  def defaults
    state.flap_power              = 11
    state.gravity                 = 0.9
    state.ceiling                 = 600
    state.ceiling_flap_power      = 6
    state.wall_countdown_length   = 100
    state.wall_gap_size           = 100
    state.wall_countdown        ||= 0
    state.hi_score              ||= 0
    state.score                 ||= 0
    state.walls                 ||= []
    state.x_starting_point      ||= 640
    state.x                     ||= state.x_starting_point
    state.y                     ||= 500
    state.z                     ||= -120
    state.dy                    ||= 0
    state.scene                 ||= :menu
    state.scene_at              ||= 0
    state.difficulty            ||= :normal
    state.new_difficulty        ||= :normal
    state.countdown             ||= 4.seconds
    state.flash_at              ||= 0
  end

  def render
    outputs.sounds << "sounds/flappy-song.ogg" if state.tick_count == 1
    render_score
    render_menu
    render_game
  end

  def render_score
    outputs.primitives << { x: 10, y: 710, z: game_text_z, text: "HI SCORE: #{state.hi_score}", **large_white_typeset }
    outputs.primitives << { x: 10, y: 680, z: game_text_z, text: "SCORE: #{state.score}", **large_white_typeset }
    outputs.primitives << { x: 10, y: 650, z: game_text_z, text: "DIFFICULTY: #{state.difficulty.upcase}", **large_white_typeset }
  end

  def render_menu
    return unless state.scene == :menu
    render_overlay

    outputs.labels << { x: 640, y: 700, z: menu_text_z, text: "Flappy Dragon", size_enum: 50, alignment_enum: 1, **white }
    outputs.labels << { x: 640, y: 500, z: menu_text_z, text: "Instructions: Press Spacebar to flap. Don't die.", size_enum: 4, alignment_enum: 1, **white }
    outputs.labels << { x: 430, y: 430, z: menu_text_z, text: "[Tab]    Change difficulty", size_enum: 4, alignment_enum: 0, **white }
    outputs.labels << { x: 430, y: 400, z: menu_text_z, text: "[Enter]  Start at New Difficulty ", size_enum: 4, alignment_enum: 0, **white }
    outputs.labels << { x: 430, y: 370, z: menu_text_z, text: "[Escape] Cancel/Resume ", size_enum: 4, alignment_enum: 0, **white }
    outputs.labels << { x: 640, y: 300, z: menu_text_z, text: "(mouse, touch, and game controllers work, too!) ", size_enum: 4, alignment_enum: 1, **white }
    outputs.labels << { x: 640, y: 200, z: menu_text_z, text: "Difficulty: #{state.new_difficulty.capitalize}", size_enum: 4, alignment_enum: 1, **white }

    outputs.labels << { x: 10, y: 100, z: menu_text_z, text: "Code:   @amirrajan",     **white }
    outputs.labels << { x: 10, y:  80, z: menu_text_z, text: "Art:    @mobypixel",     **white }
    outputs.labels << { x: 10, y:  60, z: menu_text_z, text: "Music:  @mobypixel",     **white }
    outputs.labels << { x: 10, y:  40, z: menu_text_z, text: "Engine: DragonRuby GTK", **white }
  end

  def render_overlay
    overlay_rect = grid.rect.scale_rect(1.5, 0, 0)
    outputs.primitives << { x: overlay_rect.x - overlay_rect.w,
                            y: overlay_rect.y - overlay_rect.h,
                            w: overlay_rect.w * 4,
                            h: overlay_rect.h * 2,
                            z: menu_overlay_z,
                            r: 0, g: 0, b: 0, a: 230 }.solid!
  end

  def render_game
    outputs.background_color = [0, 0, 0]
    render_game_over
    render_background
    render_walls
    render_dragon
    render_flash
  end

  def render_game_over
    return unless state.scene == :game
    outputs.labels << { x: 638, y: 358, text: score_text,     z: game_text_z - 1,  size_enum: 20, alignment_enum: 1 }
    outputs.labels << { x: 635, y: 360, text: score_text,     z: game_text_z,  size_enum: 20, alignment_enum: 1, r: 255, g: 255, b: 255 }
    outputs.labels << { x: 638, y: 428, text: countdown_text, z: game_text_z - 1,  size_enum: 20, alignment_enum: 1 }
    outputs.labels << { x: 635, y: 430, text: countdown_text, z: game_text_z,  size_enum: 20, alignment_enum: 1, r: 255, g: 255, b: 255 }
  end

  def render_background
    scroll_point_at   = state.tick_count
    scroll_point_at   = state.scene_at if state.scene == :menu
    scroll_point_at   = state.death_at if state.countdown > 0
    scroll_point_at ||= 0

    outputs.sprites << { x: -640, y: -360, z: background_z, w: 1280 * 2, h: 720 * 2, path: 'sprites/background.png' }
    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_back.png',   0.25, 1)
    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_middle.png', 0.50, 50)
    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_front.png',  1.00, 100, -80)
  end

  def scrolling_background at, path, rate, z, y = 0
    rate *= 2
    w = 1440 * 2
    h =  720 * 2
    [
      { x: w - at.*(rate) % w - w.half.half, y: y * 2 - 360, z: background_z + z, w: w, h: h, path: path },
      { x: 0 - at.*(rate) % w - w.half.half, y: y * 2 - 360, z: background_z + z, w: w, h: h, path: path },
    ]
  end

  def render_walls
    state.walls.each do |w|
      w.top_section = { x: w.x,
                        y: w.bottom_height - 720,
                        z: -120,
                        w: 100,
                        h: 720,
                        path: 'sprites/wall.png',
                        angle: 180 }

      w.bottom_section = { x: w.x,
                           y: w.top_y,
                           z: -120,
                           w: 100,
                           h: 720,
                           path: 'sprites/wallbottom.png',
                           angle: 0}
      w.sprites = [
        model_for(w.top_section),
        model_for(w.bottom_section)
      ]
    end

    outputs.sprites << state.walls.find_all { |w| w.x >= state.x }.reverse.map(&:sprites)
    outputs.sprites << state.walls.find_all { |w| w.x <  state.x }.map(&:sprites)
  end

  def model_for wall
    ratio = (wall.x - state.x_starting_point).abs.fdiv(2560 + state.x_starting_point)
    z_ratio = ratio ** 2
    z_offset = (2560 * 2) * z_ratio
    x_offset = z_offset * 0.25

    if wall.x < state.x
      x_offset *= -1
    end

    distance_from_background_to_flappy = (background_z - flappy_sprite_z).abs
    distance_to_front = z_offset

    if -z_offset < background_z + 100 + wall.w * 2
      a = 0
    else
      percentage_to_front = distance_to_front / distance_from_background_to_flappy
      a = 255 * (1 - percentage_to_front)
    end


    back  = { x:     wall.x + x_offset,
              y:     wall.y,
              z:     wall.z - wall.w.half - z_offset,
              a:     a,
              w:     wall.w,
              h:     wall.h,
              path:  wall.path,
              angle: wall.angle }
    front = { x:     wall.x + x_offset,
              y:     wall.y,
              z:     wall.z + wall.w.half - z_offset,
              a:     a,
              w:     wall.w,
              h:     wall.h,
              path:  wall.path,
              angle: wall.angle }
    left  = { x:     wall.x - wall.w.half + x_offset,
              y:     wall.y,
              z:     wall.z - z_offset,
              a:     a,
              angle_y: 90,
              w:     wall.w,
              h:     wall.h,
              path:  wall.path,
              angle: wall.angle }
    right = { x:     wall.x + wall.w.half + x_offset,
              y:     wall.y,
              z:     wall.z - z_offset,
              a:     a,
              angle_y: 90,
              w:     wall.w,
              h:     wall.h,
              path:  wall.path,
              angle: wall.angle }
    if    (wall.x - wall.w - state.x).abs < 200
      [back, left, right, front]
    elsif wall.x < state.x
      [back, left, front, right]
    else
      [back, right, front, left]
    end
  end

  def render_dragon
    state.show_death = true if state.countdown == 3.seconds

    if state.show_death == false || !state.death_at
      animation_index = state.flapped_at.frame_index 6, 2, false if state.flapped_at
      sprite_name = "sprites/dragon_fly#{animation_index.or(0) + 1}.png"
      state.dragon_sprite = { x: state.x, y: state.y, z: state.z, w: 100, h: 80, path: sprite_name, angle: state.dy * 1.2 }
    else
      sprite_name = "sprites/dragon_die.png"
      state.dragon_sprite = { x: state.x, y: state.y, z: state.z, w: 100, h: 80, path: sprite_name, angle: state.dy * 1.2 }
      sprite_changed_elapsed    = state.death_at.elapsed_time - 1.seconds
      state.dragon_sprite.angle += (sprite_changed_elapsed ** 1.3) * state.death_fall_direction * -1
      state.dragon_sprite.x     += (sprite_changed_elapsed ** 1.2) * state.death_fall_direction
      state.dragon_sprite.y     += (sprite_changed_elapsed * 14 - sprite_changed_elapsed ** 1.6)
      state.z     += 0.3
    end

    outputs.sprites << state.dragon_sprite
  end

  def render_flash
    return unless state.flash_at

    outputs.primitives << { **grid.rect.to_hash,
                            **white,
                            z: flash_z,
                            a: 255 * state.flash_at.ease(20, :flip) }.solid!

    state.flash_at = 0 if state.flash_at.elapsed_time > 20
  end

  def calc
    return unless state.scene == :game
    reset_game if state.countdown == 1
    state.countdown -= 1 and return if state.countdown > 0
    calc_walls
    calc_flap
    calc_game_over
  end

  def calc_walls
    state.walls.each { |w| w.x -= 8 }

    walls_count_before_removal = state.walls.length

    state.walls.reject! { |w| w.x < -2560 + state.x_starting_point }

    state.score += 1 if state.walls.count < walls_count_before_removal

    state.wall_countdown -= 1 and return if state.wall_countdown > 0

    state.walls << state.new_entity(:wall) do |w|
      w.x             = 2560 + state.x_starting_point
      w.opening       = grid.top
                            .randomize(:ratio)
                            .greater(200)
                            .lesser(520)
      w.opening -= w.opening * 0.5
      w.bottom_height = w.opening - state.wall_gap_size
      w.top_y         = w.opening + state.wall_gap_size
    end

    state.wall_countdown = state.wall_countdown_length
  end

  def calc_flap
    state.y += state.dy
    state.dy = state.dy.lesser state.flap_power
    state.dy -= state.gravity
    return if state.y < state.ceiling
    state.y  = state.ceiling
    state.dy = state.dy.lesser state.ceiling_flap_power
  end

  def calc_game_over
    return unless game_over?

    state.death_at = state.tick_count
    state.death_from = state.walls.first
    state.death_fall_direction = -1
    state.death_fall_direction =  1 if state.x > state.death_from.x
    outputs.sounds << "sounds/hit-sound.wav"
    begin_countdown
  end

  def process_inputs
    process_inputs_menu
    process_inputs_game
  end

  def process_inputs_menu
    return unless state.scene == :menu

    changediff = inputs.keyboard.key_down.tab || inputs.controller_one.key_down.select
    if inputs.mouse.click
      p = inputs.mouse.click.point
      if (p.y >= 165) && (p.y < 200) && (p.x >= 500) && (p.x < 800)
        changediff = true
      end
    end

    if changediff
      case state.new_difficulty
      when :easy
        state.new_difficulty = :normal
      when :normal
        state.new_difficulty = :hard
      when :hard
        state.new_difficulty = :flappy
      when :flappy
        state.new_difficulty = :easy
      end
    end

    if inputs.keyboard.key_down.enter || inputs.controller_one.key_down.start || inputs.controller_one.key_down.a
      state.difficulty = state.new_difficulty
      change_to_scene :game
      reset_game false
      state.hi_score = 0
      begin_countdown
    end

    if inputs.keyboard.key_down.escape || (inputs.mouse.click && !changediff) || inputs.controller_one.key_down.b
      state.new_difficulty = state.difficulty
      change_to_scene :game
    end
  end

  def process_inputs_game
    return unless state.scene == :game

    clicked_menu = false
    if inputs.mouse.click
      p = inputs.mouse.click.point
      clicked_menu = (p.y >= 620) && (p.x < 275)
    end

    if clicked_menu || inputs.keyboard.key_down.escape || inputs.keyboard.key_down.enter || inputs.controller_one.key_down.start
      change_to_scene :menu
    elsif (inputs.mouse.down || inputs.mouse.click || inputs.keyboard.key_down.space || inputs.controller_one.key_down.a) && state.countdown == 0
      state.dy = 0
      state.dy += state.flap_power
      state.flapped_at = state.tick_count
      outputs.sounds << "sounds/fly-sound.wav"
    end
  end

  def white
    { r: 255, g: 255, b: 255 }
  end

  def large_white_typeset
    { size_enum: 5, alignment_enum: 0, r: 255, g: 255, b: 255 }
  end

  def at_beginning?
    state.walls.count == 0
  end

  def dragon_collision_box
    { x: state.dragon_sprite.x,
      y: state.dragon_sprite.y,
      w: state.dragon_sprite.w,
      h: state.dragon_sprite.h }
         .scale_rect(1.0 - collision_forgiveness, 0.5, 0.5)
         .rect_shift_right(10)
         .rect_shift_up(state.dy * 2)
  end

  def game_over?
    return true if state.y <= 0.-(500 * collision_forgiveness) && !at_beginning?

    state.walls
         .find_all { |w| w.top_section && w.bottom_section }
         .flat_map { |w| [w.top_section, w.bottom_section] }
         .any?     { |s| s.intersect_rect?(dragon_collision_box) }
  end

  def collision_forgiveness
    case state.difficulty
    when :easy
      0.9
    when :normal
      0.7
    when :hard
      0.5
    when :flappy
      0.3
    else
      0.9
    end
  end

  def countdown_text
    state.countdown ||= -1
    return ""          if state.countdown == 0
    return "GO!"       if state.countdown.idiv(60) == 0
    return "GAME OVER" if state.death_at
    return "READY?"
  end

  def begin_countdown
    state.countdown = 4.seconds
  end

  def score_text
    return ""                        unless state.countdown > 1.seconds
    return ""                        unless state.death_at
    return "SCORE: 0 (LOL)"          if state.score == 0
    return "HI SCORE: #{state.score}" if state.score == state.hi_score
    return "SCORE: #{state.score}"
  end

  def reset_game set_flash = true
    state.flash_at = state.tick_count if set_flash
    state.walls = []
    state.y = 500
    state.x =  state.x_starting_point
    state.z = flappy_sprite_z
    state.dy = 0
    state.hi_score = state.hi_score.greater(state.score)
    state.score = 0
    state.wall_countdown = state.wall_countdown_length.fdiv(2)
    state.show_death = false
    state.death_at = nil
  end

  def change_to_scene scene
    state.scene = scene
    state.scene_at = state.tick_count
    inputs.keyboard.clear
    inputs.controller_one.clear
  end
end

$flappy_dragon = FlappyDragon.new

def tick_game args
  $flappy_dragon.grid = args.grid
  $flappy_dragon.inputs = args.inputs
  $flappy_dragon.state = args.state
  $flappy_dragon.outputs = args.outputs
  $flappy_dragon.tick
end

$gtk.reset

    Cubeworld main.rb link

    # ./samples/14_vr/08_cubeworld_vr/app/main.rb
require 'app/tick.rb'

def tick args
  args.gtk.start_server! port: 9001, enable_in_prod: true
  $game ||= Game.new
  $game.args = args
  $game.tick
end

    Cubeworld tick.rb link

    # ./samples/14_vr/08_cubeworld_vr/app/tick.rb
class Game
  include MatrixFunctions

  attr_gtk

  def cube x:, y:, z:, angle_x:, angle_y:, angle_z:;
    combined = mul (rotate_x angle_x),
                   (rotate_y angle_y),
                   (rotate_z angle_z),
                   (translate x, y, z)

    face_1 = mul_triangles state.baseline_cube.face_1, combined
    face_2 = mul_triangles state.baseline_cube.face_2, combined
    face_3 = mul_triangles state.baseline_cube.face_3, combined
    face_4 = mul_triangles state.baseline_cube.face_4, combined
    face_5 = mul_triangles state.baseline_cube.face_5, combined
    face_6 = mul_triangles state.baseline_cube.face_6, combined

    [
      face_1,
      face_2,
      face_3,
      face_4,
      face_5,
      face_6
    ]
  end

  def random_point
    r = { xr: 2.randomize(:ratio) - 1,
          yr: 2.randomize(:ratio) - 1,
          zr: 2.randomize(:ratio) - 1 }
    if (r.xr ** 2 + r.yr ** 2 + r.zr ** 2) > 1.0
      return random_point
    else
      return r
    end
  end

  def random_cube_attributes
    state.cube_count.map_with_index do |i|
      point_on_sphere = random_point
      radius = rand * 10 + 3
      {
        x: point_on_sphere.xr * radius,
        y: point_on_sphere.yr * radius,
        z: 6.4 + point_on_sphere.zr * radius
      }
    end
  end

  def defaults
    state.cube_count ||= 1
    state.cube_attributes ||= random_cube_attributes
    if !state.baseline_cube
      state.baseline_cube = {
        face_1: [
          [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
          [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
        ],
        face_2: [
          [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
          [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
        ],
        face_3: [
          [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
          [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
        ],
        face_4: [
          [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
          [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
        ],
        face_5: [
          [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
          [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
        ],
        face_6: [
          [vec4(0, 0, 0, 1),   vec4(0.5, 0, 0, 1),   vec4(0, 0.5, 0, 1)],
          [vec4(0.5, 0, 0, 1), vec4(0.5, 0.5, 0, 1), vec4(0, 0.5, 0, 1)]
        ]
      }

      state.baseline_cube.face_1 = mul_triangles state.baseline_cube.face_1,
                                                 (translate -0.25, -0.25, 0),
                                                 (translate  0, 0, 0.25)

      state.baseline_cube.face_2 = mul_triangles state.baseline_cube.face_2,
                                                 (translate -0.25, -0.25, 0),
                                                 (translate  0, 0, -0.25)

      state.baseline_cube.face_3 = mul_triangles state.baseline_cube.face_3,
                                                 (translate -0.25, -0.25, 0),
                                                 (rotate_y 90),
                                                 (translate -0.25,  0, 0)

      state.baseline_cube.face_4 = mul_triangles state.baseline_cube.face_4,
                                                 (translate -0.25, -0.25, 0),
                                                 (rotate_y 90),
                                                 (translate  0.25,  0, 0)

      state.baseline_cube.face_5 = mul_triangles state.baseline_cube.face_5,
                                                 (translate -0.25, -0.25, 0),
                                                 (rotate_x 90),
                                                 (translate  0,  0.25, 0)

      state.baseline_cube.face_6 = mul_triangles state.baseline_cube.face_6,
                                                 (translate -0.25, -0.25, 0),
                                                 (rotate_x 90),
                                                 (translate  0,  -0.25, 0)
    end
  end

  def tick
    args.grid.origin_center!
    defaults

    if inputs.controller_one.key_down.a
      state.cube_count += 1
      state.cube_attributes = random_cube_attributes
    elsif inputs.controller_one.key_down.b
      state.cube_count -= 1 if state.cube_count > 1
      state.cube_attributes = random_cube_attributes
    end

    state.cube_attributes.each do |c|
      render_cube (cube x: c.x, y: c.y, z: c.z,
                        angle_x: state.tick_count,
                        angle_y: state.tick_count,
                        angle_z: state.tick_count)
    end

    args.outputs.background_color = [255, 255, 255]
    framerate_primitives = args.gtk.current_framerate_primitives
    framerate_primitives.find { |p| p.text }.each { |p| p.z = 1 }
    framerate_primitives[-1].text = "cube count: #{state.cube_count} (#{state.cube_count * 12} triangles)"
    args.outputs.primitives << framerate_primitives
  end

  def translate dx, dy, dz
    mat4 1, 0, 0, dx,
         0, 1, 0, dy,
         0, 0, 1, dz,
         0, 0, 0,  1
  end

  def rotate_x angle_d
    cos_t = Math.cos angle_d.to_radians
    sin_t = Math.sin angle_d.to_radians
    mat4  1,     0,      0, 0,
          0, cos_t, -sin_t, 0,
          0, sin_t,  cos_t, 0,
          0,     0,      0, 1
  end

  def rotate_y angle_d
    cos_t = Math.cos angle_d.to_radians
    sin_t = Math.sin angle_d.to_radians
    mat4  cos_t,  0, sin_t, 0,
          0,      1, 0,     0,
          -sin_t, 0, cos_t, 0,
          0,      0, 0,     1
  end

  def rotate_z angle_d
    cos_t = Math.cos angle_d.to_radians
    sin_t = Math.sin angle_d.to_radians
    mat4 cos_t, -sin_t, 0, 0,
         sin_t,  cos_t, 0, 0,
         0,      0,     1, 0,
         0,      0,     0, 1
  end

  def mul_triangles model, *mul_def
    model.map do |vecs|
      vecs.map do |vec|
        vec = mul vec, *mul_def
      end
    end
  end

  def render_cube cube
    render_face cube[0]
    render_face cube[1]
    render_face cube[2]
    render_face cube[3]
    render_face cube[4]
    render_face cube[5]
  end

  def render_face face
    triangle_1 = face[0]
    args.outputs.sprites << {
      x:  triangle_1[0].x * 100,   y: triangle_1[0].y * 100,  z: triangle_1[0].z * 100,
      x2: triangle_1[1].x * 100,  y2: triangle_1[1].y * 100, z2: triangle_1[1].z * 100,
      x3: triangle_1[2].x * 100,  y3: triangle_1[2].y * 100, z3: triangle_1[2].z * 100,
      source_x:   0, source_y:   0,
      source_x2: 80, source_y2:  0,
      source_x3:  0, source_y3: 80,
      path: 'sprites/square/blue.png'
    }

    triangle_2 = face[1]
    args.outputs.sprites << {
      x:  triangle_2[0].x * 100,   y: triangle_2[0].y * 100,  z: triangle_2[0].z * 100,
      x2: triangle_2[1].x * 100,  y2: triangle_2[1].y * 100, z2: triangle_2[1].z * 100,
      x3: triangle_2[2].x * 100,  y3: triangle_2[2].y * 100, z3: triangle_2[2].z * 100,
      source_x:  80, source_y:   0,
      source_x2: 80, source_y2: 80,
      source_x3:  0, source_y3: 80,
      path: 'sprites/square/blue.png'
    }
  end
end

    Genre 3d link

    3d Cube - main.rb link

    # ./samples/99_genre_3d/01_3d_cube/app/main.rb
STARTX             = 0.0
STARTY             = 0.0
ENDY               = 20.0
ENDX               = 20.0
SPINPOINT          = 10
SPINDURATION       = 400
POINTSIZE          = 8
BOXDEPTH           = 40
YAW                = 1
DISTANCE           = 10

def tick args
  args.outputs.background_color = [0, 0, 0]
  a = Math.sin(args.state.tick_count / SPINDURATION) * Math.tan(args.state.tick_count / SPINDURATION)
  s = Math.sin(a)
  c = Math.cos(a)
  x = STARTX
  y = STARTY
  offset_x = (1280 - (ENDX - STARTX)) / 2
  offset_y =  (360 - (ENDY - STARTY)) / 2

  srand(1)
  while y < ENDY do
    while x < ENDX do
      if (y == STARTY ||
          y == (ENDY / 0.5) * 2 ||
          y == (ENDY / 0.5) * 2 + 0.5 ||
          y == ENDY - 0.5 ||
          x == STARTX ||
          x == ENDX - 0.5)
        z = rand(BOXDEPTH)
        z *= Math.sin(a / 2)
        x -= SPINPOINT
        u = (x * c) - (z * s)
        v = (x * s) + (z * c)
        k = DISTANCE.fdiv(100) + (v / 500 * YAW)
        u = u / k
        v = y / k
        w = POINTSIZE / 10 / k
        args.outputs.sprites << { x: offset_x + u - w, y: offset_y + v - w, w: w, h: w, path: 'sprites/square-blue.png'}
        x += SPINPOINT
      end
      x += 0.5
    end
    y += 0.5
    x = STARTX
  end
end

$gtk.reset

    Wireframe - main.rb link

    # ./samples/99_genre_3d/02_wireframe/app/main.rb
def tick args
  args.state.model   ||= Object3D.new('data/shuttle.off')
  args.state.mtx     ||= rotate3D(0, 0, 0)
  args.state.inv_mtx ||= rotate3D(0, 0, 0)
  delta_mtx          = rotate3D(args.inputs.up_down * 0.01, input_roll(args) * 0.01, args.inputs.left_right * 0.01)
  args.outputs.lines << args.state.model.edges
  args.state.model.fast_3x3_transform! args.state.inv_mtx
  args.state.inv_mtx = mtx_mul(delta_mtx.transpose, args.state.inv_mtx)
  args.state.mtx     = mtx_mul(args.state.mtx, delta_mtx)
  args.state.model.fast_3x3_transform! args.state.mtx
  args.outputs.background_color = [0, 0, 0]
  args.outputs.debug << args.gtk.framerate_diagnostics_primitives
end

def input_roll args
  roll = 0
  roll += 1 if args.inputs.keyboard.e
  roll -= 1 if args.inputs.keyboard.q
  roll
end

def rotate3D(theta_x = 0.1, theta_y = 0.1, theta_z = 0.1)
  c_x, s_x = Math.cos(theta_x), Math.sin(theta_x)
  c_y, s_y = Math.cos(theta_y), Math.sin(theta_y)
  c_z, s_z = Math.cos(theta_z), Math.sin(theta_z)
  rot_x    = [[1, 0, 0], [0, c_x, -s_x], [0, s_x, c_x]]
  rot_y    = [[c_y, 0, s_y], [0, 1, 0], [-s_y, 0, c_y]]
  rot_z    = [[c_z, -s_z, 0], [s_z, c_z, 0], [0, 0, 1]]
  mtx_mul(mtx_mul(rot_x, rot_y), rot_z)
end

def mtx_mul(a, b)
  is = (0...a.length)
  js = (0...b[0].length)
  ks = (0...b.length)
  is.map do |i|
    js.map do |j|
      ks.map do |k|
        a[i][k] * b[k][j]
      end.reduce(&:plus)
    end
  end
end

class Object3D
  attr_reader :vert_count, :face_count, :edge_count, :verts, :faces, :edges

  def initialize(path)
    @vert_count = 0
    @face_count = 0
    @edge_count = 0
    @verts      = []
    @faces      = []
    @edges      = []
    _init_from_file path
  end

  def _init_from_file path
    file_lines = $gtk.read_file(path).split("\n")
                     .reject { |line| line.start_with?('#') || line.split(' ').length == 0 } # Strip out simple comments and blank lines
                     .map { |line| line.split('#')[0] } # Strip out end of line comments
                     .map { |line| line.split(' ') } # Tokenize by splitting on whitespace
    raise "OFF file did not start with OFF." if file_lines.shift != ["OFF"] # OFF meshes are supposed to begin with "OFF" as the first line.
    raise "<NVertices NFaces NEdges> line malformed" if file_lines[0].length != 3 # The second line needs to have 3 numbers. Raise an error if it doesn't.
    @vert_count, @face_count, @edge_count = file_lines.shift&.map(&:to_i) # Update the counts
    # Only the vertex and face counts need to be accurate. Raise an error if they are inaccurate.
    raise "Incorrect number of vertices and/or faces (Parsed VFE header: #{@vert_count} #{@face_count} #{@edge_count})" if file_lines.length != @vert_count + @face_count
    # Grab all the lines describing vertices.
    vert_lines = file_lines[0, @vert_count]
    # Grab all the lines describing faces.
    face_lines = file_lines[@vert_count, @face_count]
    # Create all the vertices
    @verts = vert_lines.map_with_index { |line, id| Vertex.new(line, id) }
    # Create all the faces
    @faces = face_lines.map { |line| Face.new(line, @verts) }
    # Create all the edges
    @edges = @faces.flat_map(&:edges).uniq do |edge|
      sorted = edge.sorted
      [sorted.point_a, sorted.point_b]
    end
  end

  def fast_3x3_transform! mtx
    @verts.each { |vert| vert.fast_3x3_transform! mtx }
  end
end

class Face

  attr_reader :verts, :edges

  def initialize(data, verts)
    vert_count = data[0].to_i
    vert_ids   = data[1, vert_count].map(&:to_i)
    @verts     = vert_ids.map { |i| verts[i] }
    @edges     = []
    (0...vert_count).each { |i| @edges[i] = Edge.new(verts[vert_ids[i - 1]], verts[vert_ids[i]]) }
    @edges.rotate! 1
  end
end

class Edge
  attr_reader :point_a, :point_b

  def initialize(point_a, point_b)
    @point_a = point_a
    @point_b = point_b
  end

  def sorted
    @point_a.id < @point_b.id ? self : Edge.new(@point_b, @point_a)
  end

  def draw_override ffi
    ffi.draw_line(@point_a.render_x, @point_a.render_y, @point_b.render_x, @point_b.render_y, 255, 0, 0, 128)
    ffi.draw_line(@point_a.render_x+1, @point_a.render_y, @point_b.render_x+1, @point_b.render_y, 255, 0, 0, 128)
    ffi.draw_line(@point_a.render_x, @point_a.render_y+1, @point_b.render_x, @point_b.render_y+1, 255, 0, 0, 128)
    ffi.draw_line(@point_a.render_x+1, @point_a.render_y+1, @point_b.render_x+1, @point_b.render_y+1, 255, 0, 0, 128)
  end

  def primitive_marker
    :line
  end
end

class Vertex
  attr_accessor :x, :y, :z, :id

  def initialize(data, id)
    @x  = data[0].to_f
    @y  = data[1].to_f
    @z  = data[2].to_f
    @id = id
  end

  def fast_3x3_transform! mtx
    _x, _y, _z = @x, @y, @z
    @x         = mtx[0][0] * _x + mtx[0][1] * _y + mtx[0][2] * _z
    @y         = mtx[1][0] * _x + mtx[1][1] * _y + mtx[1][2] * _z
    @z         = mtx[2][0] * _x + mtx[2][1] * _y + mtx[2][2] * _z
  end

  def render_x
    @x * (10 / (5 - @y)) * 170 + 640
  end

  def render_y
    @z * (10 / (5 - @y)) * 170 + 360
  end
end

    Wireframe - Data - what-is-this.txt link

    # ./samples/99_genre_3d/02_wireframe/data/what-is-this.txt
https://en.wikipedia.org/wiki/OFF_(file_format)

    Yaw Pitch Roll - main.rb link

    # ./samples/99_genre_3d/03_yaw_pitch_roll/app/main.rb
class Game
  include MatrixFunctions

  attr_gtk

  def tick
    defaults
    render
    input
  end

  def player_ship
    [
      # engine back
      (vec4  -1,  -1,  1,  0),
      (vec4  -1,   1,  1,  0),

      (vec4  -1,   1,  1,  0),
      (vec4   1,   1,  1,  0),

      (vec4   1,   1,  1,  0),
      (vec4   1,  -1,  1,  0),

      (vec4   1,  -1,  1,  0),
      (vec4  -1,  -1,  1,  0),

      # engine front
      (vec4  -1,  -1,  -1,  0),
      (vec4  -1,   1,  -1,  0),

      (vec4  -1,   1,  -1,  0),
      (vec4   1,   1,  -1,  0),

      (vec4   1,   1,  -1,  0),
      (vec4   1,  -1,  -1,  0),

      (vec4   1,  -1,  -1,  0),
      (vec4  -1,  -1,  -1,  0),

      # engine left
      (vec4  -1,   -1,  -1,  0),
      (vec4  -1,   -1,   1,  0),

      (vec4  -1,   -1,   1,  0),
      (vec4  -1,    1,   1,  0),

      (vec4  -1,    1,   1,  0),
      (vec4  -1,    1,  -1,  0),

      (vec4  -1,    1,  -1,  0),
      (vec4  -1,   -1,  -1,  0),

      # engine right
      (vec4   1,   -1,  -1,  0),
      (vec4   1,   -1,   1,  0),

      (vec4   1,   -1,   1,  0),
      (vec4   1,    1,   1,  0),

      (vec4   1,    1,   1,  0),
      (vec4   1,    1,  -1,  0),

      (vec4   1,    1,  -1,  0),
      (vec4   1,   -1,  -1,  0),

      # top front of engine to front of ship
      (vec4   1,    1,  1,  0),
      (vec4   0,   -1,  9,  0),

      (vec4   0,   -1,  9,  0),
      (vec4  -1,    1,  1,  0),

      # bottom front of engine
      (vec4   1,   -1,  1,  0),
      (vec4   0,   -1,  9,  0),

      (vec4  -1,   -1,  1,  0),
      (vec4   0,   -1,  9,  0),

      # right wing
      # front of wing
      (vec4  1,  0.10,   1,  0),
      (vec4  9,  0.10,  -1,  0),

      (vec4   9,  0.10,  -1,  0),
      (vec4  10,  0.10,  -2,  0),

      # back of wing
      (vec4  1,  0.10,  -1,  0),
      (vec4  9,  0.10,  -1,  0),

      (vec4  10,  0.10,  -2,  0),
      (vec4   8,  0.10,  -1,  0),

      # front of wing
      (vec4  1,  -0.10,   1,  0),
      (vec4  9,  -0.10,  -1,  0),

      (vec4   9,  -0.10,  -1,  0),
      (vec4  10,  -0.10,  -2,  0),

      # back of wing
      (vec4  1,  -0.10,  -1,  0),
      (vec4  9,  -0.10,  -1,  0),

      (vec4  10,  -0.10,  -2,  0),
      (vec4   8,  -0.10,  -1,  0),

      # left wing
      # front of wing
      (vec4  -1,  0.10,   1,  0),
      (vec4  -9,  0.10,  -1,  0),

      (vec4  -9,  0.10,  -1,  0),
      (vec4  -10,  0.10,  -2,  0),

      # back of wing
      (vec4  -1,  0.10,  -1,  0),
      (vec4  -9,  0.10,  -1,  0),

      (vec4  -10,  0.10,  -2,  0),
      (vec4  -8,  0.10,  -1,  0),

      # front of wing
      (vec4  -1,  -0.10,   1,  0),
      (vec4  -9,  -0.10,  -1,  0),

      (vec4  -9,  -0.10,  -1,  0),
      (vec4  -10,  -0.10,  -2,  0),

      # back of wing
      (vec4  -1,  -0.10,  -1,  0),
      (vec4  -9,  -0.10,  -1,  0),
      (vec4  -10,  -0.10,  -2,  0),
      (vec4   -8,  -0.10,  -1,  0),

      # left fin
      # top
      (vec4  -1,  0.10,  1,  0),
      (vec4  -1,  3,  -3,  0),

      (vec4  -1,  0.10,  -1,  0),
      (vec4  -1,  3,  -3,  0),

      (vec4  -1.1,  0.10,  1,  0),
      (vec4  -1.1,  3,  -3,  0),

      (vec4  -1.1,  0.10,  -1,  0),
      (vec4  -1.1,  3,  -3,  0),

      # bottom
      (vec4  -1,  -0.10,  1,  0),
      (vec4  -1,  -2,  -2,  0),

      (vec4  -1,  -0.10,  -1,  0),
      (vec4  -1,  -2,  -2,  0),

      (vec4  -1.1,  -0.10,  1,  0),
      (vec4  -1.1,  -2,  -2,  0),

      (vec4  -1.1,  -0.10,  -1,  0),
      (vec4  -1.1,  -2,  -2,  0),

      # right fin
      (vec4   1,  0.10,  1,  0),
      (vec4   1,  3,  -3,  0),

      (vec4   1,  0.10,  -1,  0),
      (vec4   1,  3,  -3,  0),

      (vec4   1.1,  0.10,  1,  0),
      (vec4   1.1,  3,  -3,  0),

      (vec4   1.1,  0.10,  -1,  0),
      (vec4   1.1,  3,  -3,  0),

      # bottom
      (vec4   1,  -0.10,  1,  0),
      (vec4   1,  -2,  -2,  0),

      (vec4   1,  -0.10,  -1,  0),
      (vec4   1,  -2,  -2,  0),

      (vec4   1.1,  -0.10,  1,  0),
      (vec4   1.1,  -2,  -2,  0),

      (vec4   1.1,  -0.10,  -1,  0),
      (vec4   1.1,  -2,  -2,  0),
    ]
  end

  def defaults
    state.points ||= player_ship
    state.shifted_points ||= state.points.map { |point| point }

    state.scale   ||= 1
    state.angle_x ||= 0
    state.angle_y ||= 0
    state.angle_z ||= 0
  end

  def angle_z_matrix degrees
    cos_t = Math.cos degrees.to_radians
    sin_t = Math.sin degrees.to_radians
    (mat4 cos_t, -sin_t, 0, 0,
          sin_t,  cos_t, 0, 0,
          0,      0,     1, 0,
          0,      0,     0, 1)
  end

  def angle_y_matrix degrees
    cos_t = Math.cos degrees.to_radians
    sin_t = Math.sin degrees.to_radians
    (mat4  cos_t,  0, sin_t, 0,
           0,      1, 0,     0,
           -sin_t, 0, cos_t, 0,
           0,      0, 0,     1)
  end

  def angle_x_matrix degrees
    cos_t = Math.cos degrees.to_radians
    sin_t = Math.sin degrees.to_radians
    (mat4  1,     0,      0, 0,
           0, cos_t, -sin_t, 0,
           0, sin_t,  cos_t, 0,
           0,     0,      0, 1)
  end

  def scale_matrix factor
    (mat4 factor,      0,      0, 0,
          0,      factor,      0, 0,
          0,           0, factor, 0,
          0,           0,      0, 1)
  end

  def input
    if (inputs.keyboard.shift && inputs.keyboard.p)
      state.scale -= 0.1
    elsif  inputs.keyboard.p
      state.scale += 0.1
    end

    if inputs.mouse.wheel
      state.scale += inputs.mouse.wheel.y
    end

    state.scale = state.scale.clamp(0.1, 1000)

    if (inputs.keyboard.shift && inputs.keyboard.y) || inputs.keyboard.right
      state.angle_y += 1
    elsif (inputs.keyboard.y) || inputs.keyboard.left
      state.angle_y -= 1
    end

    if (inputs.keyboard.shift && inputs.keyboard.x) || inputs.keyboard.down
      state.angle_x -= 1
    elsif (inputs.keyboard.x || inputs.keyboard.up)
      state.angle_x += 1
    end

    if inputs.keyboard.shift && inputs.keyboard.z
      state.angle_z += 1
    elsif inputs.keyboard.z
      state.angle_z -= 1
    end

    if inputs.keyboard.zero
      state.angle_x = 0
      state.angle_y = 0
      state.angle_z = 0
    end

    angle_x = state.angle_x
    angle_y = state.angle_y
    angle_z = state.angle_z
    scale   = state.scale

    s_matrix = scale_matrix state.scale
    x_matrix = angle_z_matrix angle_z
    y_matrix = angle_y_matrix angle_y
    z_matrix = angle_x_matrix angle_x

    state.shifted_points = state.points.map do |point|
      (mul point, y_matrix, x_matrix, z_matrix, s_matrix).merge(original: point)
    end
  end

  def thick_line line
    [
      line.merge(y: line.y - 1, y2: line.y2 - 1, r: 0, g: 0, b: 0),
      line.merge(x: line.x - 1, x2: line.x2 - 1, r: 0, g: 0, b: 0),
      line.merge(x: line.x - 0, x2: line.x2 - 0, r: 0, g: 0, b: 0),
      line.merge(y: line.y + 1, y2: line.y2 + 1, r: 0, g: 0, b: 0),
      line.merge(x: line.x + 1, x2: line.x2 + 1, r: 0, g: 0, b: 0)
    ]
  end

  def render
    outputs.lines << state.shifted_points.each_slice(2).map do |(p1, p2)|
      perc = 0
      thick_line({ x:  p1.x.*(10) + 640, y:  p1.y.*(10) + 320,
                   x2: p2.x.*(10) + 640, y2: p2.y.*(10) + 320,
                   r: 255 * perc,
                   g: 255 * perc,
                   b: 255 * perc })
    end

    outputs.labels << [ 10, 700, "angle_x: #{state.angle_x.to_sf}", 0]
    outputs.labels << [ 10, 670, "x, shift+x", 0]

    outputs.labels << [210, 700, "angle_y: #{state.angle_y.to_sf}", 0]
    outputs.labels << [210, 670, "y, shift+y", 0]

    outputs.labels << [410, 700, "angle_z: #{state.angle_z.to_sf}", 0]
    outputs.labels << [410, 670, "z, shift+z", 0]

    outputs.labels << [610, 700, "scale: #{state.scale.to_sf}", 0]
    outputs.labels << [610, 670, "p, shift+p", 0]
  end
end

$game = Game.new

def tick args
  $game.args = args
  $game.tick
end

def set_angles x, y, z
  $game.state.angle_x = x
  $game.state.angle_y = y
  $game.state.angle_z = z
end

$gtk.reset

    Ray Caster - main.rb link

    # ./samples/99_genre_3d/04_ray_caster/app/main.rb
# https://github.com/BrennerLittle/DragonRubyRaycast
# https://github.com/3DSage/OpenGL-Raycaster_v1
# https://www.youtube.com/watch?v=gYRrGTC7GtA&ab_channel=3DSage

def tick args
  defaults args
  calc args
  render args
  args.outputs.sprites << { x: 0, y: 0, w: 1280 * 2.66, h: 720 * 2.25, path: :screen }
  args.outputs.labels  << { x: 30, y: 30.from_top, text: "FPS: #{args.gtk.current_framerate.to_sf}" }
end

def defaults args
  args.state.stage ||= {
    w: 8,
    h: 8,
    sz: 64,
    layout: [
      1, 1, 1, 1, 1, 1, 1, 1,
      1, 0, 1, 0, 0, 0, 0, 1,
      1, 0, 1, 0, 0, 1, 0, 1,
      1, 0, 1, 0, 0, 0, 0, 1,
      1, 0, 0, 0, 0, 0, 0, 1,
      1, 0, 0, 0, 0, 1, 0, 1,
      1, 0, 0, 0, 0, 0, 0, 1,
      1, 1, 1, 1, 1, 1, 1, 1,
    ]
  }

  args.state.player ||= {
    x: 250,
    y: 250,
    dx: 1,
    dy: 0,
    angle: 0
  }
end

def calc args
  xo = 0

  if args.state.player.dx < 0
    xo = -20
  else
    xo = 20
  end

  yo = 0

  if args.state.player.dy < 0
    yo = -20
  else
    yo = 20
  end

  ipx = args.state.player.x.idiv 64.0
  ipx_add_xo = (args.state.player.x + xo).idiv 64.0
  ipx_sub_xo = (args.state.player.x - xo).idiv 64.0

  ipy = args.state.player.y.idiv 64.0
  ipy_add_yo = (args.state.player.y + yo).idiv 64.0
  ipy_sub_yo = (args.state.player.y - yo).idiv 64.0

  if args.inputs.keyboard.right
    args.state.player.angle -= 5
    args.state.player.angle = args.state.player.angle % 360
    args.state.player.dx = args.state.player.angle.cos_d
    args.state.player.dy = -args.state.player.angle.sin_d
  end

  if args.inputs.keyboard.left
    args.state.player.angle += 5
    args.state.player.angle = args.state.player.angle % 360
    args.state.player.dx = args.state.player.angle.cos_d
    args.state.player.dy = -args.state.player.angle.sin_d
  end

  if args.inputs.keyboard.up
    if args.state.stage.layout[ipy * args.state.stage.w + ipx_add_xo] == 0
      args.state.player.x += args.state.player.dx * 5
    end

    if args.state.stage.layout[ipy_add_yo * args.state.stage.w + ipx] == 0
      args.state.player.y += args.state.player.dy * 5
    end
  end

  if args.inputs.keyboard.down
    if args.state.stage.layout[ipy * args.state.stage.w + ipx_sub_xo] == 0
      args.state.player.x -= args.state.player.dx * 5
    end

    if args.state.stage.layout[ipy_sub_yo * args.state.stage.w + ipx] == 0
      args.state.player.y -= args.state.player.dy * 5
    end
  end
end

def render args
  args.outputs[:screen].transient!
  args.outputs[:screen].sprites << { x: 0,
                                     y: 160,
                                     w: 750,
                                     h: 160,
                                     path: :pixel,
                                     r: 89,
                                     g: 125,
                                     b: 206 }

  args.outputs[:screen].sprites << { x: 0,
                                     y: 0,
                                     w: 750,
                                     h: 160,
                                     path: :pixel,
                                     r: 117,
                                     g: 113,
                                     b: 97 }


  ra = (args.state.player.angle + 30) % 360

  60.times do |r|
    dof = 0
    side = 0
    dis_v = 100000
    ra_tan = ra.tan_d

    if ra.cos_d > 0.001
      rx = ((args.state.player.x >> 6) << 6) + 64
      ry = (args.state.player.x - rx) * ra_tan + args.state.player.y;
      xo = 64
      yo = -xo * ra_tan
    elsif ra.cos_d < -0.001
      rx = ((args.state.player.x >> 6) << 6) - 0.0001
      ry = (args.state.player.x - rx) * ra_tan + args.state.player.y
      xo = -64
      yo = -xo * ra_tan
    else
      rx = args.state.player.x
      ry = args.state.player.y
      dof = 8
    end

    while dof < 8
      mx = rx >> 6
      mx = mx.to_i
      my = ry >> 6
      my = my.to_i
      mp = my * args.state.stage.w + mx
      if mp > 0 && mp < args.state.stage.w * args.state.stage.h && args.state.stage.layout[mp] == 1
        dof = 8
        dis_v = ra.cos_d * (rx - args.state.player.x) - ra.sin_d * (ry - args.state.player.y)
      else
        rx += xo
        ry += yo
        dof += 1
      end
    end

    vx = rx
    vy = ry

    dof = 0
    dis_h = 100000
    ra_tan = 1.0 / ra_tan

    if ra.sin_d > 0.001
      ry = ((args.state.player.y >> 6) << 6) - 0.0001;
      rx = (args.state.player.y - ry) * ra_tan + args.state.player.x;
      yo = -64;
      xo = -yo * ra_tan;
    elsif ra.sin_d < -0.001
      ry = ((args.state.player.y >> 6) << 6) + 64;
      rx = (args.state.player.y - ry) * ra_tan + args.state.player.x;
      yo = 64;
      xo = -yo * ra_tan;
    else
      rx = args.state.player.x
      ry = args.state.player.y
      dof = 8
    end

    while dof < 8
      mx = (rx) >> 6
      my = (ry) >> 6
      mp = my * args.state.stage.w + mx
      if mp > 0 && mp < args.state.stage.w * args.state.stage.h && args.state.stage.layout[mp] == 1
        dof = 8
        dis_h = ra.cos_d * (rx - args.state.player.x) - ra.sin_d * (ry - args.state.player.y)
      else
        rx += xo
        ry += yo
        dof += 1
      end
    end

    color = { r: 52, g: 101, b: 36 }

    if dis_v < dis_h
      rx = vx
      ry = vy
      dis_h = dis_v
      color = { r: 109, g: 170, b: 44 }
    end

    ca = (args.state.player.angle - ra) % 360
    dis_h = dis_h * ca.cos_d
    line_h = (args.state.stage.sz * 320) / (dis_h)
    line_h = 320 if line_h > 320

    line_off = 160 - (line_h >> 1)

    args.outputs[:screen].sprites << {
      x: r * 8,
      y: line_off,
      w: 8,
      h: line_h,
      path: :pixel,
      **color
    }

    ra = (ra - 1) % 360
  end
end

    Ray Caster Advanced - main.rb link

    # ./samples/99_genre_3d/04_ray_caster_advanced/app/main.rb
=begin

This sample is a more advanced example of raycasting that extends the previous 04_ray_caster sample.
Refer to the prior sample to to understand the fundamental raycasting algorithm.
This sample adds:
 * higher resolution of raycasting
 * Wall textures
 * Simple "drop off" lighting
 * Weapon firing
 * Drawing of sprites within the level.

# Contributors outside of DragonRuby who also hold Copyright:
# - James Stocks: https://github.com/james-stocks

=end

# https://github.com/BrennerLittle/DragonRubyRaycast
# https://github.com/3DSage/OpenGL-Raycaster_v1
# https://www.youtube.com/watch?v=gYRrGTC7GtA&ab_channel=3DSage

def tick args
  defaults args
  update_player args
  update_missiles args
  update_enemies args
  render args
  args.outputs.sprites << { x: 0, y: 0, w: 1280 * 1.5, h: 720 * 1.2, path: :screen }
  args.outputs.labels  << { x: 30, y: 30.from_top, text: "FPS: #{args.gtk.current_framerate.to_sf} X: #{args.state.player.x} Y: #{args.state.player.y}" }
end

def defaults args
  args.state.stage ||= {
    w: 8,       # Width of the tile map
    h: 8,       # Height of the tile map
    sz: 64,     # To define a 3D space, define a size (in arbitrary units) we consider one map tile to be.
    layout: [
      1, 1, 1, 1, 2, 1, 1, 1,
      1, 0, 1, 0, 0, 0, 0, 1,
      1, 0, 1, 0, 0, 3, 0, 1,
      1, 0, 1, 0, 0, 0, 0, 2,
      1, 0, 0, 0, 0, 0, 0, 1,
      1, 0, 0, 0, 0, 3, 0, 1,
      1, 0, 0, 0, 0, 0, 0, 1,
      1, 1, 1, 2, 1, 1, 1, 1,
    ]
  }

  args.state.player ||= {
    x: 250,
    y: 250,
    dx: 1,
    dy: 0,
    angle: 0,
    fire_cooldown_wait: 0,
    fire_cooldown_duration: 15
  }

  # Add an initial alien enemy.
  # The :bright property indicates that this entity doesn't produce light and should appear dimmer over distance.
  args.state.enemies ||= [{ x: 280, y: 280, type: :alien, bright: false, expired: false }]
  args.state.missiles ||= []
  args.state.splashes ||= []
end

# Update the player's input and movement
def update_player args

  player = args.state.player
  player.fire_cooldown_wait -= 1 if player.fire_cooldown_wait > 0

  xo = 0

  if player.dx < 0
    xo = -20
  else
    xo = 20
  end

  yo = 0

  if player.dy < 0
    yo = -20
  else
    yo = 20
  end

  ipx = player.x.idiv 64.0
  ipx_add_xo = (player.x + xo).idiv 64.0
  ipx_sub_xo = (player.x - xo).idiv 64.0

  ipy = player.y.idiv 64.0
  ipy_add_yo = (player.y + yo).idiv 64.0
  ipy_sub_yo = (player.y - yo).idiv 64.0

  if args.inputs.keyboard.right
    player.angle -= 5
    player.angle = player.angle % 360
    player.dx = player.angle.cos_d
    player.dy = -player.angle.sin_d
  end

  if args.inputs.keyboard.left
    player.angle += 5
    player.angle = player.angle % 360
    player.dx = player.angle.cos_d
    player.dy = -player.angle.sin_d
  end

  if args.inputs.keyboard.up
    if args.state.stage.layout[ipy * args.state.stage.w + ipx_add_xo] == 0
      player.x += player.dx * 5
    end

    if args.state.stage.layout[ipy_add_yo * args.state.stage.w + ipx] == 0
      player.y += player.dy * 5
    end
  end

  if args.inputs.keyboard.down
    if args.state.stage.layout[ipy * args.state.stage.w + ipx_sub_xo] == 0
      player.x -= player.dx * 5
    end

    if args.state.stage.layout[ipy_sub_yo * args.state.stage.w + ipx] == 0
      player.y -= player.dy * 5
    end
  end

  if args.inputs.keyboard.key_down.space && player.fire_cooldown_wait == 0
    m = { x: player.x, y: player.y, angle: player.angle, speed: 6, type: :missile, bright: true, expired: false }
    # Immediately move the missile forward a frame so it spawns ahead of the player
    m.x += m.angle.cos_d * m.speed
    m.y -= m.angle.sin_d * m.speed
    args.state.missiles << m
    player.fire_cooldown_wait = player.fire_cooldown_duration
  end
end

def update_missiles args
  # Remove expired missiles by mapping expired missiles to `nil` and then calling `compact!` to
  # remove nil entries.
  args.state.missiles.map! { |m| m.expired ? nil : m }
  args.state.missiles.compact!

  args.state.missiles.each do |m|
    new_x = m.x + m.angle.cos_d * m.speed
    new_y = m.y - m.angle.sin_d * m.speed
    # Hit enemies
    args.state.enemies.each do |e|
        if (new_x - e.x).abs < 16 && (new_y - e.y).abs < 16
            e.expired = true
            m.expired = true
            args.state.splashes << { x: m.x, y: m.y, ttl: 5, type: :splash, bright: true }
            next
        end
    end
    # Hit walls
    if(args.state.stage.layout[(new_y / 64).to_i * args.state.stage.w + (new_x / 64).to_i] != 0)
      m.expired = true
      args.state.splashes << { x: m.x, y: m.y, ttl: 5, type: :splash, bright: true }
    else
      m.x = new_x
      m.y = new_y
    end
  end
  args.state.splashes.map! { |s| s.ttl <= 0 ? nil : s }
  args.state.splashes.compact!
  args.state.splashes.each do |s|
    s.ttl -= 1
  end
end

def update_enemies args
    args.state.enemies.map! { |e| e.expired ?  nil : e }
    args.state.enemies.compact!
end

def render args
  # Render the sky
  args.outputs[:screen].transient!
  args.outputs[:screen].sprites << { x: 0,
                                     y: 320,
                                     w: 960,
                                     h: 320,
                                     path: :pixel,
                                     r: 89,
                                     g: 125,
                                     b: 206 }

  # Render the floor
  args.outputs[:screen].sprites << { x: 0,
                                     y: 0,
                                     w: 960,
                                     h: 320,
                                     path: :pixel,
                                     r: 117,
                                     g: 113,
                                     b: 97 }

  ra = (args.state.player.angle + 30) % 360

  # Collect sprites for the raycast view into an array - these will all be rendered with a single draw call.
  # This gives a substantial performance improvement over the previous sample where there was one draw call
  # per sprite.
  sprites_to_draw = []

  # Save distances of each wall hit. This is used subsequently when drawing sprites.
  depths = []

  # Cast 120 rays across 60 degress - we'll consider the next 0.5 degrees each ray
  120.times do |r|

    # The next ~120 lines are largely the same as the previous sample. The changes are:
    # - Increment by 0.5 degrees instead of 1 degree for the next ray.
    # - When a wall hit is found, the distance is stored in the `depths` array.
    #   - `depths` is used later when rendering enemies and bullet.
    # - We draw a slice of a wall texture instead of a solid color.
    # - The wall strip for the array hit is appended to `sprites_to_draw` instead of being drawn immediately.
    dof = 0
    max_dof = 8
    dis_v = 100000

    ra_tan = Math.tan(ra * Math::PI / 180)

    if ra.cos_d > 0.001
      rx = ((args.state.player.x >> 6) << 6) + 64

      ry = (args.state.player.x - rx) * ra_tan + args.state.player.y;
      xo = 64
      yo = -xo * ra_tan
    elsif ra.cos_d < -0.001
      rx = ((args.state.player.x >> 6) << 6) - 0.0001
      ry = (args.state.player.x - rx) * ra_tan + args.state.player.y
      xo = -64
      yo = -xo * ra_tan
    else
      rx = args.state.player.x
      ry = args.state.player.y
      dof = max_dof
    end

    while dof < max_dof
      mx = rx >> 6
      mx = mx.to_i
      my = ry >> 6
      my = my.to_i
      mp = my * args.state.stage.w + mx
      if mp > 0 && mp < args.state.stage.w * args.state.stage.h && args.state.stage.layout[mp] > 0
        dof = max_dof
        dis_v = ra.cos_d * (rx - args.state.player.x) - ra.sin_d * (ry - args.state.player.y)
        wall_texture_v = args.state.stage.layout[mp]
      else
        rx += xo
        ry += yo
        dof += 1
      end
    end

    vx = rx
    vy = ry

    dof = 0
    dis_h = 100000
    ra_tan = 1.0 / ra_tan

    if ra.sin_d > 0.001
      ry = ((args.state.player.y >> 6) << 6) - 0.0001;
      rx = (args.state.player.y - ry) * ra_tan + args.state.player.x;
      yo = -64;
      xo = -yo * ra_tan;
    elsif ra.sin_d < -0.001
      ry = ((args.state.player.y >> 6) << 6) + 64;
      rx = (args.state.player.y - ry) * ra_tan + args.state.player.x;
      yo = 64;
      xo = -yo * ra_tan;
    else
      rx = args.state.player.x
      ry = args.state.player.y
      dof = 8
    end

    while dof < 8
      mx = (rx) >> 6
      my = (ry) >> 6
      mp = my * args.state.stage.w + mx
      if mp > 0 && mp < args.state.stage.w * args.state.stage.h && args.state.stage.layout[mp] > 0
        dof = 8
        dis_h = ra.cos_d * (rx - args.state.player.x) - ra.sin_d * (ry - args.state.player.y)
        wall_texture = args.state.stage.layout[mp]
      else
        rx += xo
        ry += yo
        dof += 1
      end
    end

    dist = dis_h
    if dis_v < dis_h
      rx = vx
      ry = vy
      dist = dis_v
      wall_texture = wall_texture_v
    end
    # Store the distance for a wall hit at this angle
    depths << dist

    # Adjust for fish-eye across FOV
    ca = (args.state.player.angle - ra) % 360
    dist = dist * ca.cos_d
    # Determine the render height for the strip proportional to the display height
    line_h = (args.state.stage.sz * 640) / (dist)

    line_off = 320 - (line_h >> 1)

    # Tint the wall strip - the further away it is, the darker.
    tint = 1.0 - (dist / 500)

    # Wall texturing - Determine the section of source texture to use
    tx = dis_v > dis_h ? (rx.to_i % 64).to_i : (ry.to_i % 64).to_i
    # If player is looking backwards towards a tile then flip the side of the texture to sample.
    # The sample wall textures have a diagonal stripe pattern - if you comment out these 2 lines,
    # you will see what goes wrong with texturing.
    tx = 63 - tx if (ra > 180 && dis_v > dis_h)
    tx = 63 - tx if (ra > 90 && ra < 270 && dis_v < dis_h)

    sprites_to_draw << {
      x: r * 8,
      y: line_off,
      w: 8,
      h: line_h,
      path: "sprites/wall_#{wall_texture}.png",
      source_x: tx,
      source_w: 1,
      r: 255 * tint,
      g: 255 * tint,
      b: 255 * tint
    }

    # Increment the raycast angle for the next iteration of this loop
    ra = (ra - 0.5) % 360
  end

  # Render sprites
  # Use common render code for enemies, missiles and explosion splashes.
  # This works because they are all hashes with :x, :y, and :type fields.
  things_to_draw = []
  things_to_draw.push(*args.state.enemies)
  things_to_draw.push(*args.state.missiles)
  things_to_draw.push(*args.state.splashes)

  # Do a first-pass on the things to draw, calculate distance from player and then
  # sort so more-distant things are drawn first.
  things_to_draw.each do |t|
    t[:dist] = args.geometry.distance([args.state.player[:x],args.state.player[:y]],[t[:x],t[:y]]).abs
  end
  things_to_draw = things_to_draw.sort_by { |t| t[:dist] }.reverse

  # Now draw everything, most distant entities first.
  things_to_draw.each do |t|
      distance_to_thing = t[:dist]
      # The crux of drawing a sprite in a raycast view is to:
      #   1. rotate the enemy around the player's position and viewing angle to get a position relative to the view.
      #   2. Translate that position from "3D space" to screen pixels.
      # The next 6 lines get the entitiy's position relative to the player position and angle:
      tx = t[:x] - args.state.player.x
      ty = t[:y] - args.state.player.y
      cs = Math.cos(args.state.player.angle * Math::PI / 180)
      sn = Math.sin(args.state.player.angle * Math::PI / 180)
      dx = ty * cs + tx * sn
      dy = tx * cs - ty * sn

      # The next 5 lines determine the screen x and y of (the center of) the entity, and a scale
      next if dy == 0 # Avoid invalid Infinity/NaN calculations if the projected Y is 0
      ody = dy
      dx = dx*640/(dy) + 480
      dy = 32/dy + 192
      scale = 64*360/(ody / 2)

      tint = t[:bright] ? 1.0 : 1.0 - (distance_to_thing / 500)

      # Now we know the x and y on-screen for the entity, and its scale, we can draw it.
      # Simply drawing the sprite on the screen doesn't work in a raycast view because the entity might be partly obscured by a wall.
      # Instead we draw the entity in vertical strips, skipping strips if a wall is closer to the player on that strip of the screen.

      # Since dx stores the center x of the enemy on-screen, we start half the scale of the enemy to the left of dx
      x = dx - scale/2
      next if (x > 960 or (dx + scale/2 <= 0)) # Skip rendering if the X position is entirely off-screen
      strip = 0                    # Keep track of the number of strips we've drawn
      strip_width = scale / 64     # Draw the sprite in 64 strips
      sample_width = 1             # For each strip we will sample 1/64 of sprite image, here we assume 64x64 sprites

      until x >= dx + scale/2 do
          if x > 0 && x < 960
              # Here we get the distance to the wall for this strip on the screen
              wall_depth = depths[(x.to_i/8)]
              if ((distance_to_thing < wall_depth))
                  sprites_to_draw << {
                      x: x,
                      y: dy + 120 - scale * 0.6,
                      w: strip_width,
                      h: scale,
                      path: "sprites/#{t[:type]}.png",
                      source_x: strip * sample_width,
                      source_w: sample_width,
                      r: 255 * tint,
                      g: 255 * tint,
                      b: 255 * tint
                  }
              end
          end
          x += strip_width
          strip += 1
      end
  end

  # Draw all the sprites we collected in the array to the render target
  args.outputs[:screen].sprites << sprites_to_draw
end

    Genre Arcade link

    Bullet Hell - main.rb link

    # ./samples/99_genre_arcade/bullet_hell/app/main.rb
def tick args
  args.state.base_columns   ||= 10.times.map { |n| 50 * n + 1280 / 2 - 5 * 50 + 5 }
  args.state.base_rows      ||= 5.times.map { |n| 50 * n + 720 - 5 * 50 }
  args.state.offset_columns = 10.times.map { |n| (n - 4.5) * Math.sin(Kernel.tick_count.to_radians) * 12 }
  args.state.offset_rows    = 5.map { 0 }
  args.state.columns        = 10.times.map { |i| args.state.base_columns[i] + args.state.offset_columns[i] }
  args.state.rows           = 5.times.map { |i| args.state.base_rows[i] + args.state.offset_rows[i] }
  args.state.explosions     ||= []
  args.state.enemies        ||= []
  args.state.score          ||= 0
  args.state.wave           ||= 0
  if args.state.enemies.empty?
    args.state.wave      += 1
    args.state.wave_root = Math.sqrt(args.state.wave)
    args.state.enemies   = make_enemies
  end
  args.state.player         ||= {x: 620, y: 80, w: 40, h: 40, path: 'sprites/circle-gray.png', angle: 90, cooldown: 0, alive: true}
  args.state.enemy_bullets  ||= []
  args.state.player_bullets ||= []
  args.state.lives          ||= 3
  args.state.missed_shots   ||= 0
  args.state.fired_shots    ||= 0

  update_explosions args
  update_enemy_positions args

  if args.inputs.left && args.state.player[:x] > (300 + 5)
    args.state.player[:x] -= 5
  end
  if args.inputs.right && args.state.player[:x] < (1280 - args.state.player[:w] - 300 - 5)
    args.state.player[:x] += 5
  end

  args.state.enemy_bullets.each do |bullet|
    bullet[:x] += bullet[:dx]
    bullet[:y] += bullet[:dy]
  end
  args.state.player_bullets.each do |bullet|
    bullet[:x] += bullet[:dx]
    bullet[:y] += bullet[:dy]
  end

  args.state.enemy_bullets  = args.state.enemy_bullets.find_all { |bullet| bullet[:y].between?(-16, 736) }
  args.state.player_bullets = args.state.player_bullets.find_all do |bullet|
    if bullet[:y].between?(-16, 736)
      true
    else
      args.state.missed_shots += 1
      false
    end
  end

  args.state.enemies = args.state.enemies.reject do |enemy|
    if args.state.player[:alive] && 1500 > (args.state.player[:x] - enemy[:x]) ** 2 + (args.state.player[:y] - enemy[:y]) ** 2
      args.state.explosions << {x: enemy[:x] + 4, y: enemy[:y] + 4, w: 32, h: 32, path: 'sprites/explosion-0.png', age: 0}
      args.state.explosions << {x: args.state.player[:x] + 4, y: args.state.player[:y] + 4, w: 32, h: 32, path: 'sprites/explosion-0.png', age: 0}
      args.state.player[:alive] = false
      true
    else
      false
    end
  end
  args.state.enemy_bullets.each do |bullet|
    if args.state.player[:alive] && 400 > (args.state.player[:x] - bullet[:x] + 12) ** 2 + (args.state.player[:y] - bullet[:y] + 12) ** 2
      args.state.explosions << {x: args.state.player[:x] + 4, y: args.state.player[:y] + 4, w: 32, h: 32, path: 'sprites/explosion-0.png', age: 0}
      args.state.player[:alive] = false
      bullet[:despawn]          = true
    end
  end
  args.state.enemies = args.state.enemies.reject do |enemy|
    args.state.player_bullets.any? do |bullet|
      if 400 > (enemy[:x] - bullet[:x] + 12) ** 2 + (enemy[:y] - bullet[:y] + 12) ** 2
        args.state.explosions << {x: enemy[:x] + 4, y: enemy[:y] + 4, w: 32, h: 32, path: 'sprites/explosion-0.png', age: 0}
        bullet[:despawn] = true
        args.state.score += 1000 * args.state.wave
        true
      else
        false
      end
    end
  end

  args.state.player_bullets = args.state.player_bullets.reject { |bullet| bullet[:despawn] }
  args.state.enemy_bullets  = args.state.enemy_bullets.reject { |bullet| bullet[:despawn] }

  args.state.player[:cooldown] -= 1
  if args.inputs.keyboard.key_held.space && args.state.player[:cooldown] <= 0 && args.state.player[:alive]
    args.state.player_bullets << {x: args.state.player[:x] + 12, y: args.state.player[:y] + 28, w: 16, h: 16, path: 'sprites/star.png', dx: 0, dy: 8}.sprite
    args.state.fired_shots       += 1
    args.state.player[:cooldown] = 10 + 20 / args.state.wave
  end
  args.state.enemies.each do |enemy|
    if Math.rand < 0.0005 + 0.0005 * args.state.wave && args.state.player[:alive] && enemy[:move_state] == :normal
      args.state.enemy_bullets << {x: enemy[:x] + 12, y: enemy[:y] - 8, w: 16, h: 16, path: 'sprites/star.png', dx: 0, dy: -3 - args.state.wave_root}.sprite
    end
  end

  args.outputs.background_color = [0, 0, 0]
  args.outputs.primitives << args.state.enemies.map do |enemy|
    [enemy[:x], enemy[:y], 40, 40, enemy[:path], -90].sprite
  end
  args.outputs.primitives << args.state.player if args.state.player[:alive]
  args.outputs.primitives << args.state.explosions
  args.outputs.primitives << args.state.player_bullets
  args.outputs.primitives << args.state.enemy_bullets
  accuracy = args.state.fired_shots.zero? ? 1 : (args.state.fired_shots - args.state.missed_shots) / args.state.fired_shots
  args.outputs.primitives << [
    [0, 0, 300, 720, 96, 0, 0].solid,
    [1280 - 300, 0, 300, 720, 96, 0, 0].solid,
    [1280 - 290, 60, "Wave     #{args.state.wave}", 255, 255, 255].label,
    [1280 - 290, 40, "Accuracy #{(accuracy * 100).floor}%", 255, 255, 255].label,
    [1280 - 290, 20, "Score    #{(args.state.score * accuracy).floor}", 255, 255, 255].label,
  ]
  args.outputs.primitives << args.state.lives.times.map do |n|
    [1280 - 290 + 50 * n, 80, 40, 40, 'sprites/circle-gray.png', 90].sprite
  end
  #args.outputs.debug << args.gtk.framerate_diagnostics_primitives

  if (!args.state.player[:alive]) && args.state.enemy_bullets.empty? && args.state.explosions.empty? && args.state.enemies.all? { |enemy| enemy[:move_state] == :normal }
    args.state.player[:alive] = true
    args.state.player[:x]     = 624
    args.state.player[:y]     = 80
    args.state.lives          -= 1
    if args.state.lives == -1
      args.state.clear!
    end
  end
end

def make_enemies
  enemies = []
  enemies += 10.times.map { |n| {x: Math.rand * 1280 * 2 - 640, y: Math.rand * 720 * 2 + 720, row: 0, col: n, path: 'sprites/circle-orange.png', move_state: :retreat} }
  enemies += 10.times.map { |n| {x: Math.rand * 1280 * 2 - 640, y: Math.rand * 720 * 2 + 720, row: 1, col: n, path: 'sprites/circle-orange.png', move_state: :retreat} }
  enemies += 8.times.map { |n| {x: Math.rand * 1280 * 2 - 640, y: Math.rand * 720 * 2 + 720, row: 2, col: n + 1, path: 'sprites/circle-blue.png', move_state: :retreat} }
  enemies += 8.times.map { |n| {x: Math.rand * 1280 * 2 - 640, y: Math.rand * 720 * 2 + 720, row: 3, col: n + 1, path: 'sprites/circle-blue.png', move_state: :retreat} }
  enemies += 4.times.map { |n| {x: Math.rand * 1280 * 2 - 640, y: Math.rand * 720 * 2 + 720, row: 4, col: n + 3, path: 'sprites/circle-green.png', move_state: :retreat} }
  enemies
end

def update_explosions args
  args.state.explosions.each do |explosion|
    explosion[:age]  += 0.5
    explosion[:path] = "sprites/explosion-#{explosion[:age].floor}.png"
  end
  args.state.explosions = args.state.explosions.reject { |explosion| explosion[:age] >= 7 }
end

def update_enemy_positions args
  args.state.enemies.each do |enemy|
    if enemy[:move_state] == :normal
      enemy[:x]          = args.state.columns[enemy[:col]]
      enemy[:y]          = args.state.rows[enemy[:row]]
      enemy[:move_state] = :dive if Math.rand < 0.0002 + 0.00005 * args.state.wave && args.state.player[:alive]
    elsif enemy[:move_state] == :dive
      enemy[:target_x] ||= args.state.player[:x]
      enemy[:target_y] ||= args.state.player[:y]
      dx               = enemy[:target_x] - enemy[:x]
      dy               = enemy[:target_y] - enemy[:y]
      vel              = Math.sqrt(dx * dx + dy * dy)
      speed_limit      = 2 + args.state.wave_root
      if vel > speed_limit
        dx /= vel / speed_limit
        dy /= vel / speed_limit
      end
      if vel < 1 || !args.state.player[:alive]
        enemy[:move_state] = :retreat
      end
      enemy[:x] += dx
      enemy[:y] += dy
    elsif enemy[:move_state] == :retreat
      enemy[:target_x] = args.state.columns[enemy[:col]]
      enemy[:target_y] = args.state.rows[enemy[:row]]
      dx               = enemy[:target_x] - enemy[:x]
      dy               = enemy[:target_y] - enemy[:y]
      vel              = Math.sqrt(dx * dx + dy * dy)
      speed_limit      = 2 + args.state.wave_root
      if vel > speed_limit
        dx /= vel / speed_limit
        dy /= vel / speed_limit
      elsif vel < 1
        enemy[:move_state] = :normal
        enemy[:target_x]   = nil
        enemy[:target_y]   = nil
      end
      enemy[:x] += dx
      enemy[:y] += dy
    end
  end
end

    Dueling Starships - main.rb link

    # ./samples/99_genre_arcade/dueling_starships/app/main.rb
class DuelingSpaceships
  attr_gtk

  def tick
    defaults
    render
    calc
    input
  end

  def defaults
    outputs.background_color = [0, 0, 0]
    state.ship_blue       ||= new_blue_ship
    state.ship_red        ||= new_red_ship
    state.flames          ||= []
    state.bullets         ||= []
    state.ship_blue_score ||= 0
    state.ship_red_score  ||= 0
    state.stars           ||= 100.map do
      (rand + 2).yield_self do |size|
        { x: grid.w_half.randomize(:sign, :ratio),
          y: grid.h_half.randomize(:sign, :ratio),
          w: size,
          h: size,
          r: 128 + 128 * rand,
          g: 255,
          b: 255,
          path: :solid }
      end
    end
  end

  def new_ship x:, y:, angle:, path:, bullet_path:, color:;
    { x: x, y: y, w: 66, h: 66,
      dy: 0, dx: 0,
      anchor_x: 0.5, anchor_y: 0.5,
      damage: 0,
      dead: false,
      angle: angle,
      a: 255,
      path: path,
      bullet_sprite_path: bullet_path,
      color: color,
      created_at: state.tick_count,
      last_bullet_at: 0,
      fire_rate: 10 }
  end

  def new_red_ship
    new_ship x: 400,
             y: 250.randomize(:sign, :ratio),
             angle: 180, path: 'sprites/ship_red.png',
             bullet_path: 'sprites/red_bullet.png',
             color: { r: 255, g: 90, b: 90 }
  end

  def new_blue_ship
    new_ship x: -400,
             y: 250.randomize(:sign, :ratio),
             angle: 0,
             path: 'sprites/ship_blue.png',
             bullet_path: 'sprites/blue_bullet.png',
             color: { r: 110, g: 140, b: 255 }
  end

  def render
    render_instructions
    render_score
    render_universe
    render_flames
    render_ships
    render_bullets
  end

  def render_ships
    outputs.primitives << ship_prefab(state.ship_blue)
    outputs.primitives << ship_prefab(state.ship_red)
  end

  def render_instructions
    return if state.ship_blue.dx  > 0  || state.ship_blue.dy > 0  ||
              state.ship_red.dx   > 0  || state.ship_red.dy  > 0  ||
              state.flames.length > 0

    outputs.labels << { x: grid.left.shift_right(30),
                        y: grid.bottom.shift_up(30),
                        text: "Two gamepads needed to play. R1 to accelerate. Left and right on D-PAD to turn ship. Hold A to shoot. Press B to drop mines.",
                        r: 255, g: 255, b: 255 }
  end

  def calc
    calc_flames
    calc_ships
    calc_bullets
    calc_winner
  end

  def input
    input_accelerate
    input_turn
    input_bullets_and_mines
  end

  def render_score
    outputs.labels << { x: grid.left.shift_right(80),
                        y: grid.top.shift_down(40),
                        text: state.ship_blue_score,
                        size_enum: 30,
                        alignment_enum: 1, **state.ship_blue.color }

    outputs.labels << { x: grid.right.shift_left(80),
                        y: grid.top.shift_down(40),
                        text: state.ship_red_score,
                        size_enum: 30,
                        alignment_enum: 1, **state.ship_red.color }
  end

  def render_universe
    args.outputs.background_color = [0, 0, 0]
    outputs.sprites << state.stars
  end

  def apply_round_finished_alpha entity
    return entity unless state.round_finished_at
    entity.merge(a: (entity.a || 0) * state.round_finished_at.ease(2.seconds, :flip))
  end

  def ship_prefab ship
    [
      apply_round_finished_alpha(**ship,
                                 a: ship.dead ? 0 : 255 * ship.created_at.ease(2.seconds)),

      apply_round_finished_alpha(x: ship.x,
                                 y: ship.y + 100,
                                 text: "." * (5 - ship.damage.clamp(0, 5)),
                                 size_enum: 20,
                                 alignment_enum: 1,
                                 **ship.color)
    ]
  end

  def render_flames
    outputs.sprites << state.flames.map do |flame|
      apply_round_finished_alpha(flame.merge(a: 255 * flame.created_at.ease(flame.lifetime, :flip)))
    end
  end

  def render_bullets
    outputs.sprites << state.bullets.map do |b|
      apply_round_finished_alpha(b.merge(a: 255 * b.owner.created_at.ease(2.seconds)))
    end
  end

  def wrap_location! location
    location.merge! x: location.x.clamp_wrap(grid.left, grid.right),
                    y: location.y.clamp_wrap(grid.bottom, grid.top)
  end

  def calc_flames
    state.flames =
      state.flames
           .reject { |p| p.created_at.elapsed_time > p.lifetime }
           .map do |p|
             p.speed *= 0.9
             p.y += p.angle.vector_y(p.speed)
             p.x += p.angle.vector_x(p.speed)
             wrap_location! p
           end
  end

  def all_ships
    [state.ship_blue, state.ship_red]
  end

  def alive_ships
    all_ships.reject { |s| s.dead }
  end

  def calc_bullet bullet
    bullet.y += bullet.angle.vector_y(bullet.speed)
    bullet.x += bullet.angle.vector_x(bullet.speed)
    wrap_location! bullet
    explode_bullet! bullet, particle_count: 5 if bullet.created_at.elapsed_time > bullet.lifetime
    return if bullet.exploded
    return if state.round_finished
    alive_ships.each do |s|
      if s != bullet.owner && s.intersect_rect?(bullet)
        explode_bullet! bullet, particle_count: 10
        s.damage += 1
      end
    end
  end

  def calc_bullets
    state.bullets.each    { |b| calc_bullet b }
    state.bullets.reject! { |b| b.exploded }
  end

  def new_flame x:, y:, angle:, a:, lifetime:, speed:;
    { angle: angle,
      speed: speed,
      lifetime: lifetime,
      path: 'sprites/flame.png',
      x: x,
      y: y,
      w: 6,
      h: 6,
      anchor_x: 0.5,
      anchor_y: 0.5,
      created_at: state.tick_count,
      a: a }
  end

  def create_explosion! source:, particle_count:, max_speed:, lifetime:;
    state.flames.concat(particle_count.map do
                          new_flame x: source.x,
                                    y: source.y,
                                    speed: max_speed * rand,
                                    angle: 360 * rand,
                                    lifetime: lifetime,
                                    a: source.a
                        end)
  end

  def explode_bullet! bullet, particle_count: 5
    bullet.exploded = true
    create_explosion! source: bullet,
                      particle_count: particle_count,
                      max_speed: 5,
                      lifetime: 10
  end

  def calc_ship ship
    ship.x += ship.dx
    ship.y += ship.dy
    wrap_location! ship
  end

  def calc_ships
    all_ships.each { |s| calc_ship s }
    return if all_ships.any? { |s| s.dead }
    return if state.round_finished
    return unless state.ship_blue.intersect_rect?(state.ship_red)
    state.ship_blue.damage = 5
    state.ship_red.damage  = 5
  end

  def create_thruster_flames! ship
    state.flames << new_flame(x: ship.x - ship.angle.vector_x(40) + 5.randomize(:sign, :ratio),
                              y: ship.y - ship.angle.vector_y(40) + 5.randomize(:sign, :ratio),
                              angle: ship.angle + 180 + 60.randomize(:sign, :ratio),
                              speed: 5.randomize(:ratio),
                              a: 255 * ship.created_at.elapsed_time.ease(2.seconds),
                              lifetime: 30)
  end

  def input_accelerate_ship should_move_ship, ship
    return if ship.dead

    should_move_ship &&= (ship.dx + ship.dy).abs < 5

    if should_move_ship
      create_thruster_flames! ship
      ship.dx += ship.angle.vector_x 0.050
      ship.dy += ship.angle.vector_y 0.050
    else
      ship.dx *= 0.99
      ship.dy *= 0.99
    end
  end

  def input_accelerate
    input_accelerate_ship inputs.controller_one.key_held.r1 || inputs.keyboard.up, state.ship_blue
    input_accelerate_ship inputs.controller_two.key_held.r1, state.ship_red
  end

  def input_turn_ship direction, ship
    ship.angle -= 3 * direction
  end

  def input_turn
    input_turn_ship inputs.controller_one.left_right + inputs.keyboard.left_right, state.ship_blue
    input_turn_ship inputs.controller_two.left_right, state.ship_red
  end

  def new_bullet x:, y:, ship:, angle:, speed:, lifetime:;
    { owner: ship,
      angle: angle,
      speed: speed,
      lifetime: lifetime,
      created_at: state.tick_count,
      path: ship.bullet_sprite_path,
      anchor_x: 0.5,
      anchor_y: 0.5,
      w: 10,
      h: 10,
      x: x,
      y: y }
  end

  def input_bullet create_bullet, ship
    return unless create_bullet
    return if ship.dead
    return if ship.last_bullet_at.elapsed_time < ship.fire_rate

    ship.last_bullet_at = state.tick_count

    state.bullets << new_bullet(x: ship.x + ship.angle.vector_x * 32,
                                y: ship.y + ship.angle.vector_y * 32,
                                ship: ship,
                                angle: ship.angle,
                                speed: 5 + ship.dx * ship.angle.vector_x + ship.dy * ship.angle.vector_y,
                                lifetime: 120)
  end

  def input_mine create_mine, ship
    return unless create_mine
    return if ship.dead

    state.bullets << new_bullet(x: ship.x + ship.angle.vector_x * -50,
                                y: ship.y + ship.angle.vector_y * -50,
                                ship: ship,
                                angle: 360.randomize(:sign, :ratio),
                                speed: 0.02,
                                lifetime: 600)
  end

  def input_bullets_and_mines
    return if state.bullets.length > 100

    input_bullet(inputs.controller_one.key_held.a || inputs.keyboard.key_held.space,
                 state.ship_blue)

    input_mine(inputs.controller_one.key_down.b || inputs.keyboard.key_down.down,
               state.ship_blue)

    input_bullet(inputs.controller_two.key_held.a, state.ship_red)

    input_mine(inputs.controller_two.key_down.b, state.ship_red)
  end

  def calc_kill_ships
    alive_ships.find_all { |s| s.damage >= 5 }
               .each do |s|
                 s.dead = true
                 create_explosion! source: s,
                                   particle_count: 20,
                                   max_speed: 20,
                                   lifetime: 30
               end
  end

  def calc_score
    return if state.round_finished
    return if alive_ships.length > 1

    if alive_ships.first == state.ship_red
      state.ship_red_score += 1
    elsif alive_ships.first == state.ship_blue
      state.ship_blue_score += 1
    end

    state.round_finished = true
  end

  def calc_reset_ships
    return unless state.round_finished
    state.round_finished_at ||= state.tick_count
    return if state.round_finished_at.elapsed_time <= 2.seconds
    start_new_round!
  end

  def start_new_round!
    state.ship_blue = new_blue_ship
    state.ship_red  = new_red_ship
    state.round_finished = false
    state.round_finished_at = nil
    state.flames.clear
    state.bullets.clear
  end

  def calc_winner
    calc_kill_ships
    calc_score
    calc_reset_ships
  end
end

$dueling_spaceship = DuelingSpaceships.new

def tick args
  args.grid.origin_center!
  $dueling_spaceship.args = args
  $dueling_spaceship.tick
end

    arcade/flappy dragon/credits.txt link

    # ./samples/99_genre_arcade/flappy_dragon/CREDITS.txt
code: Amir Rajan, https://twitter.com/amirrajan
graphics and audio: Nick Culbertson, https://twitter.com/MobyPixel

    arcade/flappy dragon/main.rb link

    # ./samples/99_genre_arcade/flappy_dragon/app/main.rb
class FlappyDragon
  attr_accessor :grid, :inputs, :state, :outputs

  def tick
    defaults
    render
    calc
    process_inputs
  end

  def defaults
    state.flap_power              = 11
    state.gravity                 = 0.9
    state.ceiling                 = 600
    state.ceiling_flap_power      = 6
    state.wall_countdown_length   = 100
    state.wall_gap_size           = 100
    state.wall_countdown        ||= 0
    state.hi_score              ||= 0
    state.score                 ||= 0
    state.walls                 ||= []
    state.x                     ||= 50
    state.y                     ||= 500
    state.dy                    ||= 0
    state.scene                 ||= :menu
    state.scene_at              ||= 0
    state.difficulty            ||= :normal
    state.new_difficulty        ||= :normal
    state.countdown             ||= 4.seconds
    state.flash_at              ||= 0
  end

  def render
    outputs.sounds << "sounds/flappy-song.ogg" if state.tick_count == 1
    render_score
    render_menu
    render_game
  end

  def render_score
    outputs.primitives << { x: 10, y: 710, text: "HI SCORE: #{state.hi_score}", **large_white_typeset }
    outputs.primitives << { x: 10, y: 680, text: "SCORE: #{state.score}", **large_white_typeset }
    outputs.primitives << { x: 10, y: 650, text: "DIFFICULTY: #{state.difficulty.upcase}", **large_white_typeset }
  end

  def render_menu
    return unless state.scene == :menu
    render_overlay

    outputs.labels << { x: 640, y: 700, text: "Flappy Dragon", size_enum: 50, alignment_enum: 1, **white }
    outputs.labels << { x: 640, y: 500, text: "Instructions: Press Spacebar to flap. Don't die.", size_enum: 4, alignment_enum: 1, **white }
    outputs.labels << { x: 430, y: 430, text: "[Tab]    Change difficulty", size_enum: 4, alignment_enum: 0, **white }
    outputs.labels << { x: 430, y: 400, text: "[Enter]  Start at New Difficulty ", size_enum: 4, alignment_enum: 0, **white }
    outputs.labels << { x: 430, y: 370, text: "[Escape] Cancel/Resume ", size_enum: 4, alignment_enum: 0, **white }
    outputs.labels << { x: 640, y: 300, text: "(mouse, touch, and game controllers work, too!) ", size_enum: 4, alignment_enum: 1, **white }
    outputs.labels << { x: 640, y: 200, text: "Difficulty: #{state.new_difficulty.capitalize}", size_enum: 4, alignment_enum: 1, **white }

    outputs.labels << { x: 10, y: 100, text: "Code:   @amirrajan",     **white }
    outputs.labels << { x: 10, y:  80, text: "Art:    @mobypixel",     **white }
    outputs.labels << { x: 10, y:  60, text: "Music:  @mobypixel",     **white }
    outputs.labels << { x: 10, y:  40, text: "Engine: DragonRuby GTK", **white }
  end

  def render_overlay
    overlay_rect = grid.rect.scale_rect(1.1, 0, 0)
    outputs.primitives << { x: overlay_rect.x,
                            y: overlay_rect.y,
                            w: overlay_rect.w,
                            h: overlay_rect.h,
                            r: 0, g: 0, b: 0, a: 230 }.solid!
  end

  def render_game
    render_game_over
    render_background
    render_walls
    render_dragon
    render_flash
  end

  def render_game_over
    return unless state.scene == :game
    outputs.labels << { x: 638, y: 358, text: score_text,     size_enum: 20, alignment_enum: 1 }
    outputs.labels << { x: 635, y: 360, text: score_text,     size_enum: 20, alignment_enum: 1, r: 255, g: 255, b: 255 }
    outputs.labels << { x: 638, y: 428, text: countdown_text, size_enum: 20, alignment_enum: 1 }
    outputs.labels << { x: 635, y: 430, text: countdown_text, size_enum: 20, alignment_enum: 1, r: 255, g: 255, b: 255 }
  end

  def render_background
    outputs.sprites << { x: 0, y: 0, w: 1280, h: 720, path: 'sprites/background.png' }

    scroll_point_at   = state.tick_count
    scroll_point_at   = state.scene_at if state.scene == :menu
    scroll_point_at   = state.death_at if state.countdown > 0
    scroll_point_at ||= 0

    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_back.png',   0.25)
    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_middle.png', 0.50)
    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_front.png',  1.00, -80)
  end

  def scrolling_background at, path, rate, y = 0
    [
      { x:    0 - at.*(rate) % 1440, y: y, w: 1440, h: 720, path: path },
      { x: 1440 - at.*(rate) % 1440, y: y, w: 1440, h: 720, path: path }
    ]
  end

  def render_walls
    state.walls.each do |w|
      w.sprites = [
        { x: w.x, y: w.bottom_height - 720, w: 100, h: 720, path: 'sprites/wall.png',       angle: 180 },
        { x: w.x, y: w.top_y,               w: 100, h: 720, path: 'sprites/wallbottom.png', angle: 0 }
      ]
    end
    outputs.sprites << state.walls.map(&:sprites)
  end

  def render_dragon
    state.show_death = true if state.countdown == 3.seconds

    if state.show_death == false || !state.death_at
      animation_index = state.flapped_at.frame_index 6, 2, false if state.flapped_at
      sprite_name = "sprites/dragon_fly#{animation_index.or(0) + 1}.png"
      state.dragon_sprite = { x: state.x, y: state.y, w: 100, h: 80, path: sprite_name, angle: state.dy * 1.2 }
    else
      sprite_name = "sprites/dragon_die.png"
      state.dragon_sprite = { x: state.x, y: state.y, w: 100, h: 80, path: sprite_name, angle: state.dy * 1.2 }
      sprite_changed_elapsed    = state.death_at.elapsed_time - 1.seconds
      state.dragon_sprite.angle += (sprite_changed_elapsed ** 1.3) * state.death_fall_direction * -1
      state.dragon_sprite.x     += (sprite_changed_elapsed ** 1.2) * state.death_fall_direction
      state.dragon_sprite.y     += (sprite_changed_elapsed * 14 - sprite_changed_elapsed ** 1.6)
    end

    outputs.sprites << state.dragon_sprite
  end

  def render_flash
    return unless state.flash_at

    outputs.primitives << { **grid.rect.to_hash,
                            **white,
                            a: 255 * state.flash_at.ease(20, :flip) }.solid!

    state.flash_at = 0 if state.flash_at.elapsed_time > 20
  end

  def calc
    return unless state.scene == :game
    reset_game if state.countdown == 1
    state.countdown -= 1 and return if state.countdown > 0
    calc_walls
    calc_flap
    calc_game_over
  end

  def calc_walls
    state.walls.each { |w| w.x -= 8 }

    walls_count_before_removal = state.walls.length

    state.walls.reject! { |w| w.x < -100 }

    state.score += 1 if state.walls.count < walls_count_before_removal

    state.wall_countdown -= 1 and return if state.wall_countdown > 0

    state.walls << state.new_entity(:wall) do |w|
      w.x             = grid.right
      w.opening       = grid.top
                            .randomize(:ratio)
                            .greater(200)
                            .lesser(520)
      w.bottom_height = w.opening - state.wall_gap_size
      w.top_y         = w.opening + state.wall_gap_size
    end

    state.wall_countdown = state.wall_countdown_length
  end

  def calc_flap
    state.y += state.dy
    state.dy = state.dy.lesser state.flap_power
    state.dy -= state.gravity
    return if state.y < state.ceiling
    state.y  = state.ceiling
    state.dy = state.dy.lesser state.ceiling_flap_power
  end

  def calc_game_over
    return unless game_over?

    state.death_at = state.tick_count
    state.death_from = state.walls.first
    state.death_fall_direction = -1
    state.death_fall_direction =  1 if state.x > state.death_from.x
    outputs.sounds << "sounds/hit-sound.wav"
    begin_countdown
  end

  def process_inputs
    process_inputs_menu
    process_inputs_game
  end

  def process_inputs_menu
    return unless state.scene == :menu

    changediff = inputs.keyboard.key_down.tab || inputs.controller_one.key_down.select
    if inputs.mouse.click
      p = inputs.mouse.click.point
      if (p.y >= 165) && (p.y < 200) && (p.x >= 500) && (p.x < 800)
        changediff = true
      end
    end

    if changediff
      case state.new_difficulty
      when :easy
        state.new_difficulty = :normal
      when :normal
        state.new_difficulty = :hard
      when :hard
        state.new_difficulty = :flappy
      when :flappy
        state.new_difficulty = :easy
      end
    end

    if inputs.keyboard.key_down.enter || inputs.controller_one.key_down.start || inputs.controller_one.key_down.a
      state.difficulty = state.new_difficulty
      change_to_scene :game
      reset_game false
      state.hi_score = 0
      begin_countdown
    end

    if inputs.keyboard.key_down.escape || (inputs.mouse.click && !changediff) || inputs.controller_one.key_down.b
      state.new_difficulty = state.difficulty
      change_to_scene :game
    end
  end

  def process_inputs_game
    return unless state.scene == :game

    clicked_menu = false
    if inputs.mouse.click
      p = inputs.mouse.click.point
      clicked_menu = (p.y >= 620) && (p.x < 275)
    end

    if clicked_menu || inputs.keyboard.key_down.escape || inputs.keyboard.key_down.enter || inputs.controller_one.key_down.start
      change_to_scene :menu
    elsif (inputs.mouse.down || inputs.mouse.click || inputs.keyboard.key_down.space || inputs.controller_one.key_down.a) && state.countdown == 0
      state.dy = 0
      state.dy += state.flap_power
      state.flapped_at = state.tick_count
      outputs.sounds << "sounds/fly-sound.wav"
    end
  end

  def white
    { r: 255, g: 255, b: 255 }
  end

  def large_white_typeset
    { size_enum: 5, alignment_enum: 0, r: 255, g: 255, b: 255 }
  end

  def at_beginning?
    state.walls.count == 0
  end

  def dragon_collision_box
    state.dragon_sprite
         .scale_rect(1.0 - collision_forgiveness, 0.5, 0.5)
         .rect_shift_right(10)
         .rect_shift_up(state.dy * 2)
  end

  def game_over?
    return true if state.y <= 0.-(500 * collision_forgiveness) && !at_beginning?

    state.walls
        .flat_map { |w| w.sprites }
        .any? do |s|
          s && s.intersect_rect?(dragon_collision_box)
        end
  end

  def collision_forgiveness
    case state.difficulty
    when :easy
      0.9
    when :normal
      0.7
    when :hard
      0.5
    when :flappy
      0.3
    else
      0.9
    end
  end

  def countdown_text
    state.countdown ||= -1
    return ""          if state.countdown == 0
    return "GO!"       if state.countdown.idiv(60) == 0
    return "GAME OVER" if state.death_at
    return "READY?"
  end

  def begin_countdown
    state.countdown = 4.seconds
  end

  def score_text
    return ""                        unless state.countdown > 1.seconds
    return ""                        unless state.death_at
    return "SCORE: 0 (LOL)"          if state.score == 0
    return "HI SCORE: #{state.score}" if state.score == state.hi_score
    return "SCORE: #{state.score}"
  end

  def reset_game set_flash = true
    state.flash_at = state.tick_count if set_flash
    state.walls = []
    state.y = 500
    state.dy = 0
    state.hi_score = state.hi_score.greater(state.score)
    state.score = 0
    state.wall_countdown = state.wall_countdown_length.fdiv(2)
    state.show_death = false
    state.death_at = nil
  end

  def change_to_scene scene
    state.scene = scene
    state.scene_at = state.tick_count
    inputs.keyboard.clear
    inputs.controller_one.clear
  end
end

$flappy_dragon = FlappyDragon.new

def tick args
  $flappy_dragon.grid = args.grid
  $flappy_dragon.inputs = args.inputs
  $flappy_dragon.state = args.state
  $flappy_dragon.outputs = args.outputs
  $flappy_dragon.tick
end

    Pong - main.rb link

    # ./samples/99_genre_arcade/pong/app/main.rb
def tick args
  defaults args
  render args
  calc args
  input args
end

def defaults args
  args.state.ball ||= {
    debounce: 3 * 60,
    size: 10,
    size_half: 5,
    x: 640,
    y: 360,
    dx: 5.randomize(:sign),
    dy: 5.randomize(:sign)
  }

  args.state.paddle ||= {
    w: 10,
    h: 120
  }

  args.state.left_paddle  ||= { y: 360, score: 0 }
  args.state.right_paddle ||= { y: 360, score: 0 }
end

def render args
  render_center_line args
  render_scores args
  render_countdown args
  render_ball args
  render_paddles args
  render_instructions args
end

begin :render_methods
  def render_center_line args
    args.outputs.lines  << [640, 0, 640, 720]
  end

  def render_scores args
    args.outputs.labels << [
      { x: 320,
        y: 650,
        text: args.state.left_paddle.score,
        size_px: 40,
        anchor_x: 0.5,
        anchor_y: 0.5 },
      { x: 960,
        y: 650,
        text: args.state.right_paddle.score,
        size_px: 40,
        anchor_x: 0.5,
        anchor_y: 0.5 }
    ]
  end

  def render_countdown args
    return unless args.state.ball.debounce > 0
    args.outputs.labels << { x: 640,
                             y: 360,
                             text: "%.2f" % args.state.ball.debounce.fdiv(60),
                             size_px: 40,
                             anchor_x: 0.5,
                             anchor_y: 0.5 }
  end

  def render_ball args
    args.outputs.solids << solid_ball(args)
  end

  def render_paddles args
    args.outputs.solids << solid_left_paddle(args)
    args.outputs.solids << solid_right_paddle(args)
  end

  def render_instructions args
    args.outputs.labels << { x: 320,
                             y: 30,
                             text: "W and S keys to move left paddle.",
                             anchor_x: 0.5,
                             anchor_y: 0.5 }
    args.outputs.labels << { x: 920,
                             y: 30,
                             text: "O and L keys to move right paddle.",
                             anchor_x: 0.5,
                             anchor_y: 0.5 }
  end
end

def calc args
  args.state.ball.debounce -= 1 and return if args.state.ball.debounce > 0
  calc_move_ball args
  calc_collision_with_left_paddle args
  calc_collision_with_right_paddle args
  calc_collision_with_walls args
end

begin :calc_methods
  def calc_move_ball args
    args.state.ball.x += args.state.ball.dx
    args.state.ball.y += args.state.ball.dy
  end

  def calc_collision_with_left_paddle args
    if solid_left_paddle(args).intersect_rect? solid_ball(args)
      args.state.ball.dx *= -1
    elsif args.state.ball.x < 0
      args.state.right_paddle.score += 1
      calc_reset_round args
    end
  end

  def calc_collision_with_right_paddle args
    if solid_right_paddle(args).intersect_rect? solid_ball(args)
      args.state.ball.dx *= -1
    elsif args.state.ball.x > 1280
      args.state.left_paddle.score += 1
      calc_reset_round args
    end
  end

  def calc_collision_with_walls args
    if args.state.ball.y + args.state.ball.size_half > 720
      args.state.ball.y = 720 - args.state.ball.size_half
      args.state.ball.dy *= -1
    elsif args.state.ball.y - args.state.ball.size_half < 0
      args.state.ball.y = args.state.ball.size_half
      args.state.ball.dy *= -1
    end
  end

  def calc_reset_round args
    args.state.ball.x = 640
    args.state.ball.y = 360
    args.state.ball.dx = 5.randomize(:sign)
    args.state.ball.dy = 5.randomize(:sign)
    args.state.ball.debounce = 3 * 60
  end
end

def input args
  input_left_paddle args
  input_right_paddle args
end

def input_left_paddle args
  if args.inputs.controller_one.key_down.down  || args.inputs.keyboard.key_down.s
    args.state.left_paddle.y -= 40
  elsif args.inputs.controller_one.key_down.up || args.inputs.keyboard.key_down.w
    args.state.left_paddle.y += 40
  end
end

def input_right_paddle args
  if args.inputs.controller_two.key_down.down  || args.inputs.keyboard.key_down.l
    args.state.right_paddle.y -= 40
  elsif args.inputs.controller_two.key_down.up || args.inputs.keyboard.key_down.o
    args.state.right_paddle.y += 40
  end
end

def solid_ball args
  { x: args.state.ball.x,
    y: args.state.ball.y,
    w: args.state.ball.size,
    h: args.state.ball.size,
    anchor_x: 0.5,
    anchor_y: 0.5 }
end

def solid_left_paddle args
  { x: 0,
    y: args.state.left_paddle.y,
    w: args.state.paddle.w,
    h: args.state.paddle.h,
    anchor_y: 0.5 }
end

def solid_right_paddle args
  { x: 1280 - args.state.paddle.w,
    y: args.state.right_paddle.y,
    w: args.state.paddle.w,
    h: args.state.paddle.h,
    anchor_y: 0.5 }
end

    Snakemoji - main.rb link

    # ./samples/99_genre_arcade/snakemoji/app/main.rb
# coding: utf-8
################################
#  So I was working on a snake game while
#  learning DragonRuby, and at some point I had a thought
#  what if I use "😀" as a function name, surely it wont work right...?
#  RIGHT....?
#  BUT IT DID, IT WORKED
#  it all went downhill from then
#  Created by Anton K. (ai Doge)
#  https://gist.github.com/scorp200
#############LICENSE############
#  Feel free to use this anywhere and however you want
#  You can sell this to EA for $1,000,000 if you want, its completely free.
#  Just rememeber you are helping this... thing... to spread...
#  ALSO! I am not liable for any mental, physical or financial damage caused.
#############LICENSE############


class Array
  #Helper function
  def move! vector
    self.x += vector.x
    self.y += vector.y
    return self
  end

  #Helper function to draw snake body
  def draw! 🎮, 📺, color
    translate 📺.solids, 🎮.⛓, [self.x * 🎮.⚖️ + 🎮.🛶 / 2, self.y * 🎮.⚖️ + 🎮.🛶 / 2, 🎮.⚖️ - 🎮.🛶, 🎮.⚖️ - 🎮.🛶, color]
  end

  #This is where it all started, I was trying to find  good way to multiply a map by a number, * is already used so is **
  #I kept trying different combinations of symbols, when suddenly...
  def 😀 value
    self.map {|d| d * value}
  end
end

#Draw stuff with an offset
def translate output_collection, ⛓, what
  what.x += ⛓.x
  what.y += ⛓.y
  output_collection << what
end

BLUE = [33, 150, 243]
RED = [244, 67, 54]
GOLD = [255, 193, 7]
LAST = 0

def tick args
  defaults args.state
  render args.state, args.outputs
  input args.state, args.inputs
  update args.state
end

def update 🎮
  #Update every 10 frames
  if 🎮.tick_count.mod_zero? 10
    #Add new snake body piece at head's location
    🎮.🐍 << [*🎮.🤖]
    #Assign Next Direction to Direction
    🎮.🚗 = *🎮.🚦

    #Trim the snake a bit if its longer than current size
    if 🎮.🐍.length > 🎮.🛒
      🎮.🐍 = 🎮.🐍[-🎮.🛒..-1]
    end

    #Move the head in the Direction
    🎮.🤖.move! 🎮.🚗

    #If Head is outside the playing field, or inside snake's body restart game
    if 🎮.🤖.x < 0 || 🎮.🤖.x >= 🎮.🗺.x || 🎮.🤖.y < 0 || 🎮.🤖.y >= 🎮.🗺.y || 🎮.🚗 != [0, 0] && 🎮.🐍.any? {|s| s == 🎮.🤖}
      LAST = 🎮.💰
      🎮.as_hash.clear
      return
    end

    #If head lands on food add size and score
    if 🎮.🤖 == 🎮.🍎
      🎮.🛒 += 1
      🎮.💰 += (🎮.🛒 * 0.8).floor.to_i + 5
      spawn_🍎 🎮
      puts 🎮.🍎
    end
  end

  #Every second remove 1 point
  if 🎮.💰 > 0 && 🎮.tick_count.mod_zero?(60)
    🎮.💰 -= 1
  end
end

def spawn_🍎 🎮
  #Food
  🎮.🍎 ||= [*🎮.🤖]
  #Randomly spawns food inside the playing field, keep doing this if the food keeps landing on the snake's body
  while 🎮.🐍.any? {|s| s == 🎮.🍎} || 🎮.🍎 == 🎮.🤖 do
    🎮.🍎 = [rand(🎮.🗺.x), rand(🎮.🗺.y)]
  end
end

def render 🎮, 📺
  #Paint the background black
  📺.solids << [0, 0, 1280, 720, 0, 0, 0, 255]
  #Draw a border for the playing field
  translate 📺.borders, 🎮.⛓, [0, 0, 🎮.🗺.x * 🎮.⚖️, 🎮.🗺.y * 🎮.⚖️, 255, 255, 255]

  #Draw the snake's body
  🎮.🐍.map do |🐍| 🐍.draw! 🎮, 📺, BLUE end
  #Draw the head
  🎮.🤖.draw! 🎮, 📺, BLUE
  #Draw the food
  🎮.🍎.draw! 🎮, 📺, RED

  #Draw current score
  translate 📺.labels, 🎮.⛓, [5, 715, "Score: #{🎮.💰}", GOLD]
  #Draw your last score, if any
  translate 📺.labels, 🎮.⛓, [[*🎮.🤖.😀(🎮.⚖️)].move!([0, 🎮.⚖️ * 2]), "Your Last score is #{LAST}", 0, 1, GOLD] unless LAST == 0 || 🎮.🚗 != [0, 0]
  #Draw starting message, only if Direction is 0
  translate 📺.labels, 🎮.⛓, [🎮.🤖.😀(🎮.⚖️), "Press any Arrow key to start", 0, 1, GOLD] unless 🎮.🚗 != [0, 0]
end

def input 🎮, 🕹
  #Left and Right keyboard input, only change if X direction is 0
  if 🕹.keyboard.key_held.left && 🎮.🚗.x == 0
    🎮.🚦 = [-1, 0]
  elsif 🕹.keyboard.key_held.right && 🎮.🚗.x == 0
    🎮.🚦 = [1, 0]
  end

  #Up and Down keyboard input, only change if Y direction is 0
  if 🕹.keyboard.key_held.up && 🎮.🚗.y == 0
    🎮.🚦 = [0, 1]
  elsif 🕹.keyboard.key_held.down && 🎮.🚗.y == 0
    🎮.🚦 = [0, -1]
  end
end

def defaults 🎮
  #Playing field size
  🎮.🗺 ||= [20, 20]
  #Scale for drawing, screen height / Field height
  🎮.⚖️ ||= 720 / 🎮.🗺.y
  #Offset, offset all rendering to the center of the screen
  🎮.⛓ ||= [(1280 - 720).fdiv(2), 0]
  #Padding, make the snake body slightly smaller than the scale
  🎮.🛶 ||= (🎮.⚖️ * 0.2).to_i
  #Snake Size
  🎮.🛒 ||= 3
  #Snake head, the only part we are actually controlling
  🎮.🤖 ||= [🎮.🗺.x / 2, 🎮.🗺.y / 2]
  #Snake body map, follows the head
  🎮.🐍 ||= []
  #Direction the head moves to
  🎮.🚗 ||= [0, 0]
  #Next_Direction, during input check only change this variable and then when game updates asign this to Direction
  🎮.🚦 ||= [*🎮.🚗]
  #Your score
  🎮.💰 ||= 0
  #Spawns Food randomly
  spawn_🍎(🎮) unless 🎮.🍎
end

    Solar System - main.rb link

    # ./samples/99_genre_arcade/solar_system/app/main.rb
# Focused tutorial video: https://s3.amazonaws.com/s3.dragonruby.org/dragonruby-nddnug-workshop.mp4
# Workshop/Presentation which provides motivation for creating a game engine: https://www.youtube.com/watch?v=S3CFce1arC8

def defaults args
  args.outputs.background_color = [0, 0, 0]
  args.state.x ||= 640
  args.state.y ||= 360
  args.state.stars ||= 100.map do
    [1280 * rand, 720 * rand, rand.fdiv(10), 255 * rand, 255 * rand, 255 * rand]
  end

  args.state.sun ||= args.state.new_entity(:sun) do |s|
    s.s = 100
    s.path = 'sprites/sun.png'
  end

  args.state.planets = [
    [:mercury,   65,  5,          88],
    [:venus,    100, 10,         225],
    [:earth,    120, 10,         365],
    [:mars,     140,  8,         687],
    [:jupiter,  280, 30, 365 *  11.8],
    [:saturn,   350, 20, 365 *  29.5],
    [:uranus,   400, 15, 365 *    84],
    [:neptune,  440, 15, 365 * 164.8],
    [:pluto,    480,  5, 365 * 247.8],
  ].map do |name, distance, size, year_in_days|
    args.state.new_entity(name) do |p|
      p.path = "sprites/#{name}.png"
      p.distance = distance * 0.7
      p.s = size * 0.7
      p.year_in_days = year_in_days
    end
  end

  args.state.ship ||= args.state.new_entity(:ship) do |s|
    s.x = 1280 * rand
    s.y = 720 * rand
    s.angle = 0
  end
end

def to_sprite args, entity
  x = 0
  y = 0

  if entity.year_in_days
    day = args.state.tick_count
    day_in_year = day % entity.year_in_days
    entity.random_start_day ||= day_in_year * rand
    percentage_of_year = day_in_year.fdiv(entity.year_in_days)
    angle = 365 * percentage_of_year
    x = angle.vector_x(entity.distance)
    y = angle.vector_y(entity.distance)
  end

  [640 + x - entity.s.half, 360 + y - entity.s.half, entity.s, entity.s, entity.path]
end

def render args
  args.outputs.solids << [0, 0, 1280, 720]

  args.outputs.sprites << args.state.stars.map do |x, y, _, r, g, b|
    [x, y, 10, 10, 'sprites/star.png', 0, 100, r, g, b]
  end

  args.outputs.sprites << to_sprite(args, args.state.sun)
  args.outputs.sprites << args.state.planets.map { |p| to_sprite args, p }
  args.outputs.sprites << [args.state.ship.x, args.state.ship.y, 20, 20, 'sprites/ship.png', args.state.ship.angle]
end

def calc args
  args.state.stars = args.state.stars.map do |x, y, speed, r, g, b|
    x += speed
    y += speed
    x = 0 if x > 1280
    y = 0 if y > 720
    [x, y, speed, r, g, b]
  end

  if args.state.tick_count == 0
    args.audio[:bg_music] = {
      input: 'sounds/bg.ogg',
      looping: true
    }
  end
end

def process_inputs args
  if args.inputs.keyboard.left || args.inputs.controller_one.key_held.left
    args.state.ship.angle += 1
  elsif args.inputs.keyboard.right || args.inputs.controller_one.key_held.right
    args.state.ship.angle -= 1
  end

  if args.inputs.keyboard.up || args.inputs.controller_one.key_held.a
    args.state.ship.x += args.state.ship.angle.x_vector
    args.state.ship.y += args.state.ship.angle.y_vector
  end
end

def tick args
  defaults args
  render args
  calc args
  process_inputs args
end

def r
  $gtk.reset
end

    Sound Golf - main.rb link

    # ./samples/99_genre_arcade/sound_golf/app/main.rb
=begin

 APIs Listing that haven't been encountered in previous sample apps:

 - sample: Chooses random element from array.
   In this sample app, the target note is set by taking a sample from the collection
   of available notes.

 Reminders:
 - args.grid.(left|right|top|bottom): Pixel value for the boundaries of the virtual
   720 p screen (Dragon Ruby Game Toolkits's virtual resolution is always 1280x720).

 - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
   For example, if we want to create a new button, we would declare it as a new entity and
   then define its properties.

 - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - find_all: Finds all elements from a collection that meet a certain requirements (and excludes the ones that don't).

 - first: Returns the first element of an array.

 - inside_rect: Returns true or false depending on if the point is inside the rect.

 - to_sym: Returns symbol corresponding to string. Will create a symbol if it does
   not already exist.

=end

# This sample app allows users to test their musical skills by matching the piano sound that plays in each
# level to the correct note.

# Runs all the methods necessary for the game to function properly.
def tick args
  defaults args
  render args
  calc args
  input_mouse args
  tick_instructions args, "Sample app shows how to play sounds. args.outputs.sounds << \"path_to_wav.wav\""
end

# Sets default values and creates empty collections
# Initialization happens in the first frame only
def defaults args
  args.state.notes ||= []
  args.state.click_feedbacks ||= []
  args.state.current_level ||= 1
  args.state.times_wrong ||= 0 # when game starts, user hasn't guessed wrong yet
end

# Uses a label to display current level, and shows the score
# Creates a button to play the sample note, and displays the available notes that could be a potential match
def render args

  # grid.w_half positions the label in the horizontal center of the screen.
  args.outputs.labels << [args.grid.w_half, args.grid.top.shift_down(40), "Hole #{args.state.current_level} of 9", 0, 1, 0, 0, 0]

  render_score args # shows score on screen

  args.state.play_again_button ||= { x: 560, y: args.grid.h * 3 / 4 - 40, w: 160, h: 60, label: 'again' } # array definition, text/title
  args.state.play_note_button ||= { x: 560, y: args.grid.h * 3 / 4 - 40, w: 160, h: 60, label: 'play' }

  if args.state.game_over # if game is over, a "play again" button is shown
    # Calculations ensure that Play Again label is displayed in center of border
    # Remove calculations from y parameters and see what happens to border and label placement
    args.outputs.labels <<  [args.grid.w_half, args.grid.h * 3 / 4, "Play Again", 0, 1, 0, 0, 0] # outputs label
    args.outputs.borders << args.state.play_again_button # outputs border
  else # otherwise, if game is not over
    # Calculations ensure that label appears in center of border
    args.outputs.labels <<  [args.grid.w_half, args.grid.h * 3 / 4, "Play Note ##{args.state.current_level}", 0, 1, 0, 0, 0] # outputs label
    args.outputs.borders << args.state.play_note_button # outputs border
  end

  return if args.state.game_over # return if game is over

  args.outputs.labels <<   [args.grid.w_half, 400, "I think the note is a(n)...",  0, 1, 0, 0, 0] # outputs label

  # Shows all of the available notes that can be potential matches.
  available_notes.each_with_index do |note, i|
    args.state.notes[i] ||= piano_button(args, note, i + 1) # calls piano_button method on each note (creates label and border)
    args.outputs.labels <<   args.state.notes[i].label # outputs note on screen with a label and a border
    args.outputs.borders <<  args.state.notes[i].border
  end

  # Shows whether or not the user is correct by filling the screen with either red or green
  args.outputs.solids << args.state.click_feedbacks.map { |c| c.solid }
end

# Shows the score (number of times the user guesses wrong) onto the screen using labels.
def render_score args
  if args.state.times_wrong == 0 # if the user has guessed wrong zero times, the score is par
    args.outputs.labels << [args.grid.w_half, args.grid.top.shift_down(80), "Score: PAR", 0, 1, 0, 0, 0]
  else # otherwise, number of times the user has guessed wrong is shown
    args.outputs.labels << [args.grid.w_half, args.grid.top.shift_down(80), "Score: +#{args.state.times_wrong}", 0, 1, 0, 0, 0] # shows score using string interpolation
  end
end

# Sets the target note for the level and performs calculations on click_feedbacks.
def calc args
  args.state.target_note ||= available_notes.sample # chooses a note from available_notes collection as target note
  args.state.click_feedbacks.each    { |c| c.solid[-1] -= 5 } # remove this line and solid color will remain on screen indefinitely
  # comment this line out and the solid color will keep flashing on screen instead of being removed from click_feedbacks collection
  args.state.click_feedbacks.reject! { |c| c.solid[-1] <= 0 }
end

# Uses input from the user to play the target note, as well as the other notes that could be a potential match.
def input_mouse args
  return unless args.inputs.mouse.click # return unless the mouse is clicked

  # finds button that was clicked by user
  button_clicked = args.outputs.borders.find_all do |b| # go through borders collection to find all borders that meet requirements
    args.inputs.mouse.click.point.inside_rect? b # find button border that mouse was clicked inside of
  end.find_all { |b| b.is_a? Hash }.first # reject, return first element

  return unless button_clicked # return unless button_clicked as a value (a button was clicked)

  queue_click_feedback args, # calls queue_click_feedback method on the button that was clicked
                       button_clicked.x,
                       button_clicked.y,
                       button_clicked.w,
                       button_clicked.h,
                       150, 100, 200 # sets color of button to shade of purple

  if button_clicked[:label] == 'play' # if "play note" button is pressed
    args.outputs.sounds << "sounds/#{args.state.target_note}.wav" # sound of target note is output
  elsif button_clicked[:label] == 'again' # if "play game again" button is pressed
    args.state.target_note = nil # no target note
    args.state.current_level = 1 # starts at level 1 again
    args.state.times_wrong = 0 # starts off with 0 wrong guesses
    args.state.game_over = false # the game is not over (because it has just been restarted)
  else # otherwise if neither of those buttons were pressed
    args.outputs.sounds << "sounds/#{button_clicked[:label]}.wav" # sound of clicked note is played
    if button_clicked[:label] == args.state.target_note # if clicked note is target note
      args.state.target_note = nil # target note is emptied

      if args.state.current_level < 9 # if game hasn't reached level 9
        args.state.current_level += 1 # game goes to next level
      else # otherwise, if game has reached level 9
        args.state.game_over = true # the game is over
      end

      queue_click_feedback args, 0, 0, args.grid.w, args.grid.h, 100, 200, 100 # green shown if user guesses correctly
    else # otherwise, if clicked note is not target note
      args.state.times_wrong += 1 # increments times user guessed wrong
      queue_click_feedback args, 0, 0, args.grid.w, args.grid.h, 200, 100, 100 # red shown is user guesses wrong
    end
  end
end

# Creates a collection of all of the available notes as symbols
def available_notes
  [:C3, :D3, :E3, :F3, :G3, :A3, :B3, :C4]
end

# Creates buttons for each note, and sets a label (the note's name) and border for each note's button.
def piano_button args, note, position
  args.state.new_entity(:button) do |b| # declares button as new entity
    b.label  =  [460 + 40.mult(position), args.grid.h * 0.4, "#{note}", 0, 1, 0, 0, 0] # label definition
    b.border =  { x: 460 + 40.mult(position) - 20, y: args.grid.h * 0.4 - 32, w: 40, h: 40, label: note } # border definition, text/title; 20 subtracted so label is in center of border
  end
end

# Color of click feedback changes depending on what button was clicked, and whether the guess is right or wrong
# If a button is clicked, the inside of button is purple (see input_mouse method)
# If correct note is clicked, screen turns green
# If incorrect note is clicked, screen turns red (again, see input_mouse method)
def queue_click_feedback args, x, y, w, h, *color
  args.state.click_feedbacks << args.state.new_entity(:click_feedback) do |c| # declares feedback as new entity
    c.solid =  [x, y, w, h, *color, 255] # sets color
  end
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Squares - main.rb link

    # ./samples/99_genre_arcade/squares/app/main.rb
# game concept from: https://youtu.be/Tz-AinJGDIM

# This class encapsulates the logic of a button that pulses when clicked.
# It is used in the StartScene and GameOverScene classes.
class PulseButton
  # a block is passed into the constructor and is called when the button is clicked,
  # and after the pulse animation is complete
  def initialize rect, text, &on_click
    @rect = rect
    @text = text
    @on_click = on_click
    @pulse_animation_spline = [[0.0, 0.90, 1.0, 1.0], [1.0, 0.10, 0.0, 0.0]]
    @duration = 10
  end

  # the button is ticked every frame and check to see if the mouse
  # intersects the button's bounding box.
  # if it does, then pertinent information is stored in the @clicked_at variable
  # which is used to calculate the pulse animation
  def tick tick_count, mouse
    @tick_count = tick_count

    if @clicked_at && @clicked_at.elapsed_time > @duration
      @clicked_at = nil
      @on_click.call
    end

    return if !mouse.click
    return if !mouse.inside_rect? @rect
    @clicked_at = tick_count
  end

  # this function returns an array of primitives that can be rendered
  def prefab easing
    # calculate the percentage of the pulse animation that has completed
    # and use the percentage to compute the size and position of the button
    perc = if @clicked_at
             easing.ease_spline @clicked_at, @tick_count, @duration, @pulse_animation_spline
           else
             0
           end

    rect = { x: @rect.x - 50 * perc / 2,
             y: @rect.y - 50 * perc / 2,
             w: @rect.w + 50 * perc,
             h: @rect.h + 50 * perc }

    point = { x: @rect.x + @rect.w / 2, y: @rect.y + @rect.h / 2 }
    [
      { **rect, path: :pixel },
      { **point, text: @text, size_px: 32, anchor_x: 0.5, anchor_y: 0.5 }
    ]
  end
end

# the start scene is loaded when the game is started
# it contains a PulseButton that starts the game by setting the next_scene to :game and
# setting the started_at time
class StartScene
  attr_gtk

  def initialize args
    self.args = args
    @play_button = PulseButton.new layout.rect(row: 6, col: 11, w: 2, h: 2), "play" do
      state.next_scene = :game
      state.events.game_started_at = state.tick_count
      state.events.game_over_at = nil
    end
  end

  def tick
    return if state.current_scene != :start
    @play_button.tick state.tick_count, inputs.mouse
    outputs[:start_scene].transient!
    outputs[:start_scene].labels << layout.point(row: 0, col: 12).merge(text: "Squares", anchor_x: 0.5, anchor_y: 0.5, size_px: 64)
    outputs[:start_scene].primitives << @play_button.prefab(easing)
  end
end

# the game over scene is displayed when the game is over
# it contains a PulseButton that restarts the game by setting the next_scene to :game and
# setting the game_retried_at time
class GameOverScene
  attr_gtk

  def initialize args
    self.args = args
    @replay_button = PulseButton.new layout.rect(row: 6, col: 11, w: 2, h: 2), "replay" do
      state.next_scene = :game
      state.events.game_retried_at = state.tick_count
      state.events.game_over_at = nil
    end
  end

  def tick
    return if state.current_scene != :game_over
    @replay_button.tick state.tick_count, inputs.mouse
    outputs[:game_over_scene].transient!
    outputs[:game_over_scene].labels << layout.point(row: 0, col: 12).merge(text: "Game Over", anchor_x: 0.5, anchor_y: 0.5, size_px: 64)
    outputs[:game_over_scene].primitives << @replay_button.prefab(easing)

    rect = layout.point row: 2, col: 12
    outputs[:game_over_scene].primitives << rect.merge(text: state.score_last_game, anchor_x: 0.5, anchor_y: 0.5, size_px: 128, **state.red_color)

    rect = layout.point row: 4, col: 12
    outputs[:game_over_scene].primitives << rect.merge(text: "BEST #{state.best_score}", anchor_x: 0.5, anchor_y: 0.5, size_px: 64, **state.gray_color)
  end
end

# the game scene contains the game logic
class GameScene
  attr_gtk

  def tick
    defaults
    calc
    render
  end

  def defaults
    return if started_at != state.tick_count

    # initalization of scene_state variables for the game
    scene_state.score_animation_spline = [[0.0, 0.66, 1.0, 1.0], [1.0, 0.33, 0.0, 0.0]]
    scene_state.launch_particle_queue = []
    scene_state.scale_down_particles_queue = []
    scene_state.score = 0
    scene_state.square_number = 1
    scene_state.squares = []
    scene_state.square_spawn_rate = 60
    scene_state.movement_outer_rect = layout.rect(row: 11, col: 7, w: 10, h: 1).merge(path: :pixel, **state.gray_color)

    scene_state.player = { x: geometry.rect_center_point(movement_outer_rect).x,
                           y: movement_outer_rect.y,
                           w: movement_outer_rect.h,
                           h: movement_outer_rect.h,
                           path: :pixel,
                           movement_direction: 1,
                           movement_speed: 8,
                           **args.state.red_color }

    scene_state.movement_inner_rect = { x: movement_outer_rect.x + player.w * 1,
                                        y: movement_outer_rect.y,
                                        w: movement_outer_rect.w - player.w * 2,
                                        h: movement_outer_rect.h }
  end

  def calc
    calc_game_over_at
    calc_particles

    # game logic is only calculated if the current scene is :game
    return if state.current_scene != :game

    # we don't want the game loop to start for half a second after the game starts
    # this gives enough time for the game scene to animate in
    return if !started_at || started_at.elapsed_time <= 30

    calc_player
    calc_squares
    calc_game_over
  end

  # this function calculates the point in the time the game is over
  # an intermediary variable stored in scene_state.death_at is consulted
  # before transitioning to the game over scene to ensure that particle animations
  # have enough time to complete before the game over scene is rendered
  def calc_game_over_at
    return if !death_at
    return if death_at.elapsed_time < 120
    state.events.game_over_at ||= state.tick_count
  end

  # this function calculates the particles
  # there are two queues of particles that are processed
  # the launch_particle_queue contains particles that are launched when the player is hit
  # the scale_down_particles_queue contains particles that need to be scaled down
  def calc_particles
    return if !started_at

    scene_state.launch_particle_queue.each do |p|
      p.x += p.launch_angle.vector_x * p.speed
      p.y += p.launch_angle.vector_y * p.speed
      p.speed *= 0.90
      p.d_a ||= 1
      p.a -= 1 * p.d_a
      p.d_a *= 1.1
    end

    scene_state.launch_particle_queue.reject! { |p| p.a <= 0 }

    scene_state.scale_down_particles_queue.each do |p|
      next if p.start_at > state.tick_count
      p.scale_speed = p.scale_speed.abs
      p.x += p.scale_speed
      p.y += p.scale_speed
      p.w -= p.scale_speed * 2
      p.h -= p.scale_speed * 2
    end

    scene_state.scale_down_particles_queue.reject! { |p| p.w <= 0 }
  end

  def render
    return if !started_at
    scene_outputs.primitives << game_scene_score_prefab
    scene_outputs.primitives << scene_state.movement_outer_rect.merge(a: 128)
    scene_outputs.primitives << squares
    scene_outputs.primitives << player_prefab
    scene_outputs.primitives << scene_state.launch_particle_queue
    scene_outputs.primitives << scene_state.scale_down_particles_queue
  end

  # this function returns the rendering primitive for the score
  def game_scene_score_prefab
    score = if death_at
              state.score_last_game
            else
              scene_state.score
            end

    label_scale_prec = easing.ease_spline(scene_state.score_at || 0, state.tick_count, 15, scene_state.score_animation_spline)
    rect = layout.point row: 4, col: 12
    rect.merge(text: score, anchor_x: 0.5, anchor_y: 0.5, size_px: 128 + 50 * label_scale_prec, **state.gray_color)
  end

  def player_prefab
    return nil if death_at
    scale_perc = easing.ease(started_at + 30, state.tick_count, 15, :smooth_start_quad, :flip)
    player.merge(x: player.x - player.w / 2 * scale_perc, y: player.y + player.h / 2 * scale_perc,
                 w: player.w * (1 - scale_perc), h: player.h * (1 - scale_perc))
  end

  # controls the player movement and change in direction of the player when the mouse is clicked
  def calc_player
    player.x += player.movement_speed * player.movement_direction
    player.movement_direction *= -1 if !geometry.inside_rect? player, scene_state.movement_outer_rect
    return if !inputs.mouse.click
    return if !geometry.inside_rect? player, movement_inner_rect
    player.movement_direction = -player.movement_direction
  end

  # computes the squares movement
  def calc_squares
    squares << new_square if state.tick_count.zmod? scene_state.square_spawn_rate

    squares.each do |square|
      square.angle += 1
      square.x += square.dx
      square.y += square.dy
    end

    squares.reject! { |square| (square.y + square.h) < 0 }
  end

  # determines if score should be incremented or if the game should be over
  def calc_game_over
    collision = geometry.find_intersect_rect player, squares
    return if !collision
    if collision.type == :good
      scene_state.score += 1
      scene_state.score_at = state.tick_count
      scene_state.scale_down_particles_queue << collision.merge(start_at: state.tick_count, scale_speed: -2)
      squares.delete collision
    else
      generate_death_particles
      state.best_score = scene_state.score if scene_state.score > state.best_score
      squares.clear
      state.score_last_game = scene_state.score
      scene_state.score = 0
      scene_state.square_number = 1
      scene_state.death_at = state.tick_count
      state.next_scene = :game_over
    end
  end

  # this function generates the particles when the player is hit
  def generate_death_particles
    square_particles = squares.map { |b| b.merge(start_at: state.tick_count + 60, scale_speed: -1) }

    scene_state.scale_down_particles_queue.concat square_particles

    # generate 12 particles with random size, launch angle and speed
    player_particles = 12.map do
      size = rand * player.h * 0.5 + 10
      player.merge(w: size, h: size, a: 255, launch_angle: rand * 180, speed: 10 + rand * 50)
    end

    scene_state.launch_particle_queue.concat player_particles
  end

  # this function returns a new square
  # every 5th square is a good square (increases the score)
  def new_square
    x = movement_inner_rect.x + rand * movement_inner_rect.w

    dx = if x > geometry.rect_center_point(movement_inner_rect).x
           -0.9
         else
           0.9
         end

    if scene_state.square_number.zmod? 5
      type = :good
      color = state.red_color
    else
      type = :bad
      color = { r: 0, g: 0, b: 0 }
    end

    scene_state.square_number += 1

    { x: x - 16, y: 1300, w: 32, h: 32,
      dx: dx, dy: -5,
      angle: 0, type: type,
      path: :pixel, **color }
  end

  # death_at is the point in time that the player died
  # the death_at value is an intermediary variable that is used to calculate the death animation
  # before setting state.game_over_at
  def death_at
    return nil if !scene_state.death_at
    return nil if scene_state.death_at < started_at
    scene_state.death_at
  end

  # started_at is the point in time that the player started (or retried) the game
  def started_at
    state.events.game_retried_at || state.events.game_started_at
  end

  def scene_state
    state[:game_scene] ||= {}
  end

  def scene_outputs
    outputs[:game_scene].transient!
  end

  def player
    scene_state.player
  end

  def movement_outer_rect
    scene_state.movement_outer_rect
  end

  def movement_inner_rect
    scene_state.movement_inner_rect
  end

  def squares
    scene_state.squares
  end
end

class RootScene
  attr_gtk

  def initialize args
    self.args = args
    @start_scene = StartScene.new args
    @game_scene = GameScene.new
    @game_over_scene = GameOverScene.new args
  end

  def tick
    outputs.background_color = [237, 237, 237]
    init_game
    state.scene_at_tick_start = state.current_scene
    tick_start_scene
    tick_game_scene
    tick_game_over_scene
    render_scenes
    transition_to_next_scene
  end

  def tick_start_scene
    @start_scene.args = args
    @start_scene.tick
  end

  def tick_game_scene
    @game_scene.args = args
    @game_scene.tick
  end

  def tick_game_over_scene
    @game_over_scene.args = args
    @game_over_scene.tick
  end

  # initlalization of game state that is shared between scenes
  def init_game
    return if state.tick_count != 0

    state.current_scene = :start

    state.red_color = { r: 222, g: 63, b: 66 }
    state.gray_color = { r: 128, g: 128, b: 128 }

    state.events ||= {
      game_over_at: nil,
      game_started_at: nil,
      game_retried_at: nil
    }

    state.score_last_game = 0
    state.best_score = 0
    state.viewport = { x: 0, y: 0, w: 1280, h: 720 }
  end

  def transition_to_next_scene
    if state.scene_at_tick_start != state.current_scene
      raise "state.current_scene was changed during the tick. This is not allowed (use state.next_scene to set the scene to transfer to)."
    end

    return if !state.next_scene
    state.current_scene = state.next_scene
    state.next_scene = nil
  end

  # this function renders the scenes with a transition effect
  # based off of timestamps stored in state.events
  def render_scenes
    if state.events.game_over_at
      in_y = transition_in_y state.events.game_over_at
      out_y = transition_out_y state.events.game_over_at
      outputs.sprites << state.viewport.merge(y: out_y, path: :game_scene)
      outputs.sprites << state.viewport.merge(y: in_y, path: :game_over_scene)
    elsif state.events.game_retried_at
      in_y = transition_in_y state.events.game_retried_at
      out_y = transition_out_y state.events.game_retried_at
      outputs.sprites << state.viewport.merge(y: out_y, path: :game_over_scene)
      outputs.sprites << state.viewport.merge(y: in_y, path: :game_scene)
    elsif state.events.game_started_at
      in_y = transition_in_y state.events.game_started_at
      out_y = transition_out_y state.events.game_started_at
      outputs.sprites << state.viewport.merge(y: out_y, path: :start_scene)
      outputs.sprites << state.viewport.merge(y: in_y, path: :game_scene)
    else
      in_y = transition_in_y 0
      start_scene_perc = easing.ease(0, state.tick_count, 30, :smooth_stop_quad, :flip)
      outputs.sprites << state.viewport.merge(y: in_y, path: :start_scene)
    end
  end

  def transition_in_y start_at
    easing.ease(start_at, state.tick_count, 30, :smooth_stop_quad, :flip) * -1280
  end

  def transition_out_y start_at
    easing.ease(start_at, state.tick_count, 30, :smooth_stop_quad) * 1280
  end
end

def tick args
  $game ||= RootScene.new args
  $game.args = args
  $game.tick

  if args.inputs.keyboard.key_down.forward_slash
    @show_fps = !@show_fps
  end
  if @show_fps
    args.outputs.primitives << args.gtk.current_framerate_primitives
  end
end

$gtk.reset

    Twinstick - main.rb link

    # ./samples/99_genre_arcade/twinstick/app/main.rb
def tick args
  args.state.player         ||= {x: 600, y: 320, w: 80, h: 80, path: 'sprites/circle-white.png', vx: 0, vy: 0, health: 10, cooldown: 0, score: 0}
  args.state.enemies        ||= []
  args.state.player_bullets ||= []
  args.state.tick_count     ||= -1
  args.state.tick_count     += 1
  spawn_enemies args
  kill_enemies args
  move_enemies args
  move_bullets args
  move_player args
  fire_player args
  args.state.player[:r] = args.state.player[:g] = args.state.player[:b] = (args.state.player[:health] * 25.5).clamp(0, 255)
  label_color           = args.state.player[:health] <= 5 ? 255 : 0
  args.outputs.labels << [
      {
          x: args.state.player.x + 40, y: args.state.player.y + 60, alignment_enum: 1, text: "#{args.state.player[:health]} HP",
          r: label_color, g: label_color, b: label_color
      }, {
          x: args.state.player.x + 40, y: args.state.player.y + 40, alignment_enum: 1, text: "#{args.state.player[:score]} PTS",
          r: label_color, g: label_color, b: label_color, size_enum: 2 - args.state.player[:score].to_s.length,
      }
  ]
  args.outputs.sprites << [args.state.player, args.state.enemies, args.state.player_bullets]
  args.state.clear! if args.state.player[:health] < 0 # Reset the game if the player's health drops below zero
end

def spawn_enemies args
  # Spawn enemies more frequently as the player's score increases.
  if rand < (100+args.state.player[:score])/(10000 + args.state.player[:score]) || args.state.tick_count.zero?
    theta = rand * Math::PI * 2
    args.state.enemies << {
        x: 600 + Math.cos(theta) * 800, y: 320 + Math.sin(theta) * 800, w: 80, h: 80, path: 'sprites/circle-white.png',
        r: (256 * rand).floor, g: (256 * rand).floor, b: (256 * rand).floor
    }
  end
end

def kill_enemies args
  args.state.enemies.reject! do |enemy|
    # Check if enemy and player are within 80 pixels of each other (i.e. overlapping)
    if 6400 > (enemy.x - args.state.player.x) ** 2 + (enemy.y - args.state.player.y) ** 2
      # Enemy is touching player. Kill enemy, and reduce player HP by 1.
      args.state.player[:health] -= 1
    else
      args.state.player_bullets.any? do |bullet|
        # Check if enemy and bullet are within 50 pixels of each other (i.e. overlapping)
        if 2500 > (enemy.x - bullet.x + 30) ** 2 + (enemy.y - bullet.y + 30) ** 2
          # Increase player health by one for each enemy killed by a bullet after the first enemy, up to a maximum of 10 HP
          args.state.player[:health] += 1 if args.state.player[:health] < 10 && bullet[:kills] > 0
          # Keep track of how many enemies have been killed by this particular bullet
          bullet[:kills]             += 1
          # Earn more points by killing multiple enemies with one shot.
          args.state.player[:score]  += bullet[:kills]
        end
      end
    end
  end
end

def move_enemies args
  args.state.enemies.each do |enemy|
    # Get the angle from the enemy to the player
    theta   = Math.atan2(enemy.y - args.state.player.y, enemy.x - args.state.player.x)
    # Convert the angle to a vector pointing at the player
    dx, dy  = theta.to_degrees.vector 5
    # Move the enemy towards thr player
    enemy.x -= dx
    enemy.y -= dy
  end
end

def move_bullets args
  args.state.player_bullets.each do |bullet|
    # Move the bullets according to the bullet's velocity
    bullet.x += bullet[:vx]
    bullet.y += bullet[:vy]
  end
  args.state.player_bullets.reject! do |bullet|
    # Despawn bullets that are outside the screen area
    bullet.x < -20 || bullet.y < -20 || bullet.x > 1300 || bullet.y > 740
  end
end

def move_player args
  # Get the currently held direction.
  dx, dy                 = move_directional_vector args
  # Take the weighted average of the old velocities and the desired velocities.
  # Since move_directional_vector returns values between -1 and 1,
  #   and we want to limit the speed to 7.5, we multiply dx and dy by 7.5*0.1 to get 0.75
  args.state.player[:vx] = args.state.player[:vx] * 0.9 + dx * 0.75
  args.state.player[:vy] = args.state.player[:vy] * 0.9 + dy * 0.75
  # Move the player
  args.state.player.x    += args.state.player[:vx]
  args.state.player.y    += args.state.player[:vy]
  # If the player is about to go out of bounds, put them back in bounds.
  args.state.player.x    = args.state.player.x.clamp(0, 1201)
  args.state.player.y    = args.state.player.y.clamp(0, 640)
end


def fire_player args
  # Reduce the firing cooldown each tick
  args.state.player[:cooldown] -= 1
  # If the player is allowed to fire
  if args.state.player[:cooldown] <= 0
    dx, dy = shoot_directional_vector args # Get the bullet velocity
    return if dx == 0 && dy == 0 # If the velocity is zero, the player doesn't want to fire. Therefore, we just return early.
    # Add a new bullet to the list of player bullets.
    args.state.player_bullets << {
        x:     args.state.player.x + 30 + 40 * dx,
        y:     args.state.player.y + 30 + 40 * dy,
        w:     20, h: 20,
        path:  'sprites/circle-white.png',
        r:     0, g: 0, b: 0,
        vx:    10 * dx + args.state.player[:vx] / 7.5, vy: 10 * dy + args.state.player[:vy] / 7.5, # Factor in a bit of the player's velocity
        kills: 0
    }
    args.state.player[:cooldown] = 30 # Reset the cooldown
  end
end

# Custom function for getting a directional vector just for movement using WASD
def move_directional_vector args
  dx = 0
  dx += 1 if args.inputs.keyboard.d
  dx -= 1 if args.inputs.keyboard.a
  dy = 0
  dy += 1 if args.inputs.keyboard.w
  dy -= 1 if args.inputs.keyboard.s
  if dx != 0 && dy != 0
    dx *= 0.7071
    dy *= 0.7071
  end
  [dx, dy]
end

# Custom function for getting a directional vector just for shooting using the arrow keys
def shoot_directional_vector args
  dx = 0
  dx += 1 if args.inputs.keyboard.key_down.right || args.inputs.keyboard.key_held.right
  dx -= 1 if args.inputs.keyboard.key_down.left || args.inputs.keyboard.key_held.left
  dy = 0
  dy += 1 if args.inputs.keyboard.key_down.up || args.inputs.keyboard.key_held.up
  dy -= 1 if args.inputs.keyboard.key_down.down || args.inputs.keyboard.key_held.down
  if dx != 0 && dy != 0
    dx *= 0.7071
    dy *= 0.7071
  end
  [dx, dy]
end

    Genre Board Game link

    Fifteen Puzzle - main.rb link

    # ./samples/99_genre_board_game/01_fifteen_puzzle/app/main.rb
class Game
  attr_gtk

  def tick
    defaults
    calc
    render
  end

  def defaults
    # set a reliable seed when not in production so the
    # saved replay works correctly
    srand 0 if state.tick_count == 0 && !gtk.production?

    # set rendering positions/properties
    state.cell_size     ||= 64
    state.left_margin   ||= (grid.w - 4 * state.cell_size) / 2
    state.bottom_margin ||= (grid.h - 4 * state.cell_size) / 2

    # if the board isn't initialized
    if !state.board || state.win
      # generate a solvable board
      state.board = solvable_board
      state.win = false
    end
  end

  def solvable_board
    # create a random board with cells of the
    # following format:
    # {
    #   value: 1,
    #   loc: { row: 0, col: 0 },
    #   previous_loc: { row: 0, col: 0 },
    #   clicked_at: 0
    # }
    results = 16.map_with_index do |i|
      { value: i + 1 }
    end.sort_by do |cell|
      rand
    end.map_with_index do |cell, index|
      row = index.idiv 4
      col = index % 4
      cell.merge loc: { row: row, col: col },
                 previous_loc: { row: row, col: col },
                 clicked_at: 0
    end

    # determine if the board is solvable
    # by counting the number of inversions
    # (a board is solvable if the number of inversions is even)
    solvable = number_of_inversions(results).even?

    # recursively call this method until a solvable board is generated
    return solvable_board if !solvable

    return results
  end

  def number_of_inversions board
    # get the number of rows
    number_of_rows = board.map { |cell| cell.loc.row }.uniq.count

    results = 0

    # for each row
    number_of_rows.times_with_index do |row|
      # find all the cells in the row
      # and count the number of inversions for that single row
      inversions_in_row = board.find_all { |cell| cell.loc.row == row }
                               .map { |cell| cell.value }
                               .each_cons(2)
                               .map { |cell, next_cell| cell > next_cell ? 1 : 0 }
                               .sum

      # add the number of inversions for that row to the total
      results += inversions_in_row
    end

    # return the total number of inversions
    results
  end

  def render
    outputs.sprites << board.map do |cell|
      # render the board centered in the middle of the screen
      prefab = cell_prefab cell
      prefab.merge x: state.left_margin + prefab.x, y: state.bottom_margin + prefab.y
    end

    # render the win message
    if state.won_at && state.won_at.elapsed_time < 180
      # define a bezier spline that will be used to
      # fade in the win message stay visible for a little bit
      # then fade out
      spline = [
        [  0, 0.25, 0.75, 1.0],
        [1.0, 1.0,  1.0,  1.0],
        [1.0, 0.75, 0.25,   0]
      ]

      alpha_percentage = args.easing.ease_spline state.won_at,
                                                 state.tick_count,
                                                 180,
                                                 spline

      outputs.sprites << {
        x: 0,
        y: grid.h.half - 32,
        w: grid.w,
        h: 64,
        path: :pixel,
        r: 0,
        g: 0,
        b: 0,
        a: 255 * alpha_percentage,
      }

      outputs.labels << {
        x: grid.w.half,
        y: grid.h.half,
        text: "You won!",
        a: 255 * alpha_percentage,
        alignment_enum: 1,
        vertical_alignment_enum: 1,
        size_enum: 10,
        r: 255,
        g: 255,
        b: 255
      }
    end
  end

  def calc
    calc_input
    calc_win
  end

  def calc_input
    # return if the mouse isn't clicked
    return if !inputs.mouse.click

    # determine which cell was clicked
    clicked_cell = board.find do |cell|
      mouse_rect = {
        x: inputs.mouse.x - state.left_margin,
        y: inputs.mouse.y - state.bottom_margin,
        w: 1,
        h: 1,
      }
      mouse_rect.intersect_rect? render_rect(cell.loc)
    end

    # return if no cell was clicked
    return if !clicked_cell

    # find the empty cell
    empty_cell = board.find do |cell|
      cell.value == 16
    end

    # find the clicked cell's neighbors
    clicked_cell_neighbors = neighbors clicked_cell

    # return if the cell's neighbors doesn't include the empty cell
    return if !clicked_cell_neighbors.include?(empty_cell)

    # otherwise swap the clicked cell with the empty cell
    swap_with_empty clicked_cell, empty_cell
  end

  def calc_win
    sorted_values = board.sort_by { |cell| (cell.loc.col + 1) + (16 - (cell.loc.row * 4)) }
                         .map { |cell| cell.value }

    state.win = sorted_values == (1..16).to_a

    state.won_at ||= state.tick_count if state.win
  end

  def swap_with_empty cell, empty
    # take not of the cell's current location (within previous_loc)
    cell.previous_loc = cell.loc

    # swap the cell's location with the empty cell's location and vice versa
    cell.loc, empty.loc = empty.loc, cell.loc

    # take note of the current tick count (which will be used for animation)
    cell.clicked_at = state.tick_count
  end

  def cell_prefab cell
    # determine the percentage for the lerp that should be performed
    percentage = if cell.clicked_at
                   easing.ease cell.clicked_at, state.tick_count, 15, :smooth_stop_quint, :flip
                 else
                   1
                 end

    # determine the cell's current render location
    cell_rect = render_rect cell.loc

    # determine the cell's previous render location
    previous_rect = render_rect cell.previous_loc

    # compute the difference between the current and previous render locations
    x = cell_rect.x + (previous_rect.x - cell_rect.x) * percentage
    y = cell_rect.y + (previous_rect.y - cell_rect.y) * percentage

    # return the cell prefab
    { x: x,
      y: y,
      w: state.cell_size,
      h: state.cell_size,
      path: "sprites/pieces/#{cell.value}.png" }
  end

  # helper method to determine the render location of a cell in local space
  # which excludes the margins
  def render_rect loc
    {
      x: loc.col * state.cell_size,
      y: loc.row * state.cell_size,
      w: state.cell_size,
      h: state.cell_size,
    }
  end

  # helper methods to determine neighbors of a cell
  def neighbors cell
    [
      above_cell(cell),
      below_cell(cell),
      left_cell(cell),
      right_cell(cell),
    ]
  end

  def below_cell cell
    find_cell cell, -1, 0
  end

  def above_cell cell
    find_cell cell, 1, 0
  end

  def left_cell cell
    find_cell cell, 0, -1
  end

  def right_cell cell
    find_cell cell, 0, 1
  end

  def find_cell cell, d_row, d_col
    board.find do |other_cell|
      cell.loc.row == other_cell.loc.row + d_row &&
      cell.loc.col == other_cell.loc.col + d_col
    end
  end

  def board
    state.board
  end
end

def tick args
  $game ||= Game.new
  $game.args = args
  $game.tick
end

$gtk.reset

    Genre Boss Battle link

    Boss Battle Game Jam - main.rb link

    # ./samples/99_genre_boss_battle/boss_battle_game_jam/app/main.rb
class Game
  attr_gtk

  def tick
    defaults
    input
    calc
    render
  end

  def defaults
    state.high_score          ||= 0
    state.damage_render_queue ||= []
    game_reset if state.tick_count == 0 || state.start_new_game
  end

  def game_reset
    state.start_new_game      = false
    state.game_over           = false
    state.game_over_countdown = nil

    state.player.tile_size          = 64
    state.player.speed              = 4
    state.player.slash_frames       = 15
    state.player.hp                 = 3
    state.player.damaged_at         = -1000
    state.player.x                  = 50
    state.player.y                  = 400
    state.player.dir_x              =  1
    state.player.dir_y              = -1
    state.player.is_moving          = false

    state.boss.damage               = 0
    state.boss.x                    = 800
    state.boss.y                    = 400
    state.boss.w                    = 256
    state.boss.h                    = 256
    state.boss.target_x             = 800
    state.boss.target_y             = 400
    state.boss.attack_cooldown      = 600
  end

  def input
    return if state.game_over

    player.is_moving = false

    if input_attack?
      player.slash_at = state.tick_count
    end

    if !player_attacking?
      vector = inputs.directional_vector
      if vector
        next_player_x = player.x + vector.x * player.speed
        next_player_y = player.y + vector.y * player.speed
        player.x = next_player_x if player_x_inside_stage? next_player_x
        player.y = next_player_y if player_y_inside_stage? next_player_y

        player.is_moving = true

        player.dir_x = if vector.x < 0
                         -1
                       elsif vector.x > 0
                         1
                       else
                         player.dir_x
                       end

        player.dir_y = if vector.y < 0
                         -1
                       elsif vector.y > 0
                         1
                       else
                         player.dir_y
                       end
      end
    end
  end

  def input_attack?
    inputs.controller_one.key_down.a ||
    inputs.controller_one.key_down.b ||
    inputs.keyboard.key_down.j
  end

  def calc
    calc_player
    calc_boss
    calc_damage_render_queue
    calc_high_score
    calc_game_over
  end

  def calc_player
    player.slash_at = nil if !player_attacking?
    return unless player_slash_can_damage?
    if player_hit_box.intersect_rect? boss_hurt_box
      boss.damage += 1
      queue_damage player_hit_box.x + player_hit_box.w / 2 * player.dir_x,
                   player_hit_box.y + player_hit_box.h / 2
    end
  end

  def calc_boss
    boss.attack_cooldown -= 1
    if boss.attack_cooldown < 0
      boss.target_x = player.x - 100
      boss.target_y = player.y - 100
      boss.attack_cooldown = if    boss.damage > 200
                               200
                             elsif boss.damage > 150
                               300
                             elsif boss.damage > 100
                               400
                             elsif boss.damage > 50
                               500
                             else
                               600
                             end
    end

    dx = boss.target_x - boss.x
    dy = boss.target_y - boss.y
    boss.x += dx * 0.25 ** 2
    boss.y += dy * 0.25 ** 2

    if boss.intersect_rect?(player_hurt_box) && player.damaged_at.elapsed?(120)
      player.damaged_at = state.tick_count
      player.hp -= 1
      player.hp  = 0 if player.hp < 0
    end
  end

  def calc_damage_render_queue
    state.damage_render_queue.each { |label| label.a -= 5 }
    state.damage_render_queue.reject! { |l| l.a < 0 }
  end

  def calc_high_score
    state.high_score = boss.damage if boss.damage > state.high_score
  end

  def calc_game_over
    if player.hp <= 0
      state.game_over = true
      state.game_over_countdown ||= 160
    end

    state.game_over_countdown -= 1 if state.game_over_countdown
    state.start_new_game = true    if state.game_over_countdown && state.game_over_countdown < 0
  end

  def render
    render_boss
    render_player
    render_damage_queue
    render_scores
    render_instructions
    render_game_over
    # render_debug
  end

  def render_player
    outputs.labels << { x: player.x + 5,
                        y: player.y + 5,
                        text: "hp: #{player.hp}" }

    if state.game_over
      outputs.labels << { x: player.x + player.tile_size / 2,
                          y: player.y + 85,
                          text: "RIP",
                          size_enum: 2,
                          alignment_enum: 1 }
    elsif !player.damaged_at.elapsed?(120)
      outputs.labels << { x: player.x + player.tile_size / 2,
                          y: player.y + 85,
                          text: "ouch!!",
                          size_enum: 2,
                          alignment_enum: 1 }
    end

    if state.game_over
      outputs.sprites << player_sprite_stand.merge(angle: -90, flip_horizontally: false)
    elsif player.slash_at
      outputs.sprites << player_sprite_slash
    elsif player.is_moving
      outputs.sprites << player_sprite_run
    else
      outputs.sprites << player_sprite_stand
    end
  end

  def render_boss
    outputs.sprites << boss_sprite
  end

  def render_damage_queue
    outputs.labels << state.damage_render_queue
  end

  def render_scores
    outputs.labels << { x: 30, y: 30.from_top, text: "curr score: #{boss.damage}" }
    outputs.labels << { x: 30, y: 50.from_top, text: "high score: #{state.high_score}" }
  end

  def render_instructions
    outputs.labels << { x: 30, y: 70, text: "Controls:" }
    outputs.labels << { x: 30, y: 50, text: "Keyboard:   WASD/Arrow keys to move. J to attack." }
    outputs.labels << { x: 30, y: 30, text: "Controller: D-Pad to move. A/B button to attack." }
  end

  def render_game_over
    return unless state.game_over
    outputs.labels << { x: 640, y: 360, text: "GAME OVER!!!", alignment_enum: 1, size_enum: 3 }
  end

  def render_debug
    outputs.borders << player_sprite_stand
    outputs.borders << player_hurt_box
    outputs.borders << player_hit_box
    outputs.borders << boss_hurt_box
    outputs.borders << boss_hit_box
  end

  def player
    state.player
  end

  def player_x_inside_stage? player_x
    return false if player_x < 0
    return false if (player_x + player.tile_size) > 1280
    return true
  end

  def player_y_inside_stage? player_y
    return false if player_y < 0
    return false if (player_y + player.tile_size) > 720
    return true
  end

  def player_attacking?
    return false if !player.slash_at
    return false if player.slash_at.elapsed?(player.slash_frames)
    return true
  end

  def player_slash_can_damage?
    return false if !player_attacking?
    return false if (player.slash_at + player.slash_frames.idiv(2)) != state.tick_count
    return true
  end

  def player_hit_box
    sword_w = 50
    sword_h = 20
    if player.dir_x > 0
      {
        x: player.x + player.tile_size / 2 + sword_w / 2,
        y: player.y + player.tile_size / 2 - sword_h / 2,
        w: sword_w,
        h: sword_h
      }
    else
      {
        x: player.x + player.tile_size / 2 - sword_w / 2 - sword_w,
        y: player.y + player.tile_size / 2 - sword_h / 2,
        w: sword_w,
        h: sword_h
      }
    end
  end

  def player_hurt_box
    {
      x: player.x + 25,
      y: player.y + 25,
      w: 10,
      h: 10
    }
  end

  def player_sprite_run
    tile_index = 0.frame_index count:    6,
                               hold_for: 3,
                               repeat:   true

    tile_index = 0 if !player.is_moving

    {
      x:                 player.x,
      y:                 player.y,
      w:                 player.tile_size,
      h:                 player.tile_size,
      path:              'sprites/boss-battle/player-run-tile-sheet.png',
      tile_x:            0 + (tile_index * player.tile_size),
      tile_y:            0,
      tile_w:            player.tile_size,
      tile_h:            player.tile_size,
      flip_horizontally: player.dir_x > 0,
    }
  end

  def player_sprite_stand
    {
      x:                 player.x,
      y:                 player.y,
      w:                 player.tile_size,
      h:                 player.tile_size,
      path:              'sprites/boss-battle/player-stand.png',
      flip_horizontally: player.dir_x > 0,
    }
  end

  def player_sprite_slash
    tile_index   = player.slash_at.frame_index count: 5,
                                               hold_for: player.slash_frames.idiv(5),
                                               repeat: false

    tile_index ||= 0
    tile_offset = 41.25

    if player.dir_x > 0
      {
        x:                 player.x - tile_offset,
        y:                 player.y - tile_offset,
        w:                 165,
        h:                 165,
        path:              'sprites/boss-battle/player-slash-tile-sheet.png',
        tile_x:            0 + (tile_index * 128),
        tile_y:            0,
        tile_w:            128,
        tile_h:            128,
        flip_horizontally: true
      }
    else
      {
        x:                 player.x - tile_offset - tile_offset / 2,
        y:                 player.y - tile_offset,
        w:                 165,
        h:                 165,
        path:              'sprites/boss-battle/player-slash-tile-sheet.png',
        tile_x:            0 + (tile_index * 128),
        tile_y:            0,
        tile_w:            128,
        tile_h:            128,
        flip_horizontally: false
      }
    end
  end

  def boss
    state.boss
  end

  def boss_hurt_box
    {
      x: boss.x,
      y: boss.y,
      w: boss.w,
      h: boss.h
    }
  end

  def boss_hit_box
    {
      x: boss.x,
      y: boss.y,
      w: boss.w,
      h: boss.h
    }
  end

  def boss_sprite
    case boss_attack_state
    when :sleeping
      { x: boss.x,
        y: boss.y,
        w: boss.w,
        h: boss.h,
        path: 'sprites/boss-battle/boss-sleeping.png' }
    when :aware
      { x: boss.x,
        y: boss.y,
        w: boss.w,
        h: boss.h,
        path: 'sprites/boss-battle/boss-aware.png' }
    when :annoyed
      { x: boss.x,
        y: boss.y,
        w: boss.w,
        h: boss.h,
        path: 'sprites/boss-battle/boss-annoyed.png' }
    when :will_attack
      shake_x  =  2 * rand
      shake_x *= -1 if rand < 0.5

      shake_y  =  2 * rand
      shake_y *= -1 if rand < 0.5

      { x: boss.x + shake_x,
        y: boss.y + shake_x,
        w: boss.w,
        h: boss.h,
        path: 'sprites/boss-battle/boss-will-attack.png' }
    when :attacking
      flip_horizontally = false
      flip_horizontally = true if boss.target_x > boss.x

      { x: boss.x,
        y: boss.y,
        w: boss.w,
        h: boss.h,
        flip_horizontally: flip_horizontally,
        path: 'sprites/boss-battle/boss-attacking.png' }
    else
      { x: boss.x, y: boss.y, w: boss.w, h: boss.h, r: 255, g: 0, b: 0 }
    end
  end

  def boss_attack_state
    if boss.target_x.round != boss.x.round || boss.target_y.round != boss.y.round
      :attacking
    elsif boss.attack_cooldown < 30
      :will_attack
    elsif boss.attack_cooldown < 120
      :annoyed
    elsif boss.attack_cooldown < 180
      :aware
    else
      :sleeping
    end
  end

  def queue_damage x, y
    rand_x_offset = rand * 20
    rand_y_offset = rand * 20
    rand_x_offset *= -1 if rand < 0.5
    rand_y_offset *= -1 if rand < 0.5
    state.damage_render_queue << { x: x + rand_x_offset, y: y + rand_y_offset, a: 255, text: "wack!" }
  end
end

$game = Game.new

def tick args
  $game.args = args
  $game.tick
end

    Genre Crafting link

    Craft Game Starting Point - main.rb link

    # ./samples/99_genre_crafting/craft_game_starting_point/app/main.rb
# ==================================================
# A NOTE TO JAM CRAFT PARTICIPANTS:
# The comments and code in here are just as small piece of DragonRuby's capabilities.
# Be sure to check out the rest of the sample apps. Start with README.txt and go from there!
# ==================================================

# def tick args is the entry point into your game. This function is called at
# a fixed update time of 60hz (60 fps).
def tick args
  # The defaults function intitializes the game.
  defaults args

  # After the game is initialized, render it.
  render args

  # After rendering the player should be able to respond to input.
  input args

  # After responding to input, the game performs any additional calculations.
  calc args
end

def defaults args
  # hide the mouse cursor for this game, we are going to render our own cursor
  if args.state.tick_count == 0
    args.gtk.hide_cursor
  end

  args.state.click_ripples ||= []

  # everything is on a 1280x720 virtual canvas, so you can
  # hardcode locations

  # define the borders for where the inventory is located
  # args.state is a data structure that accepts any arbitrary parameters
  # so you can create an object graph without having to create any classes.

  # Bottom left is 0, 0. Top right is 1280, 720.
  # The inventory area is at the top of the screen
  # the number 80 is the size of all the sprites, so that is what is being
  # used to decide the with and height
  args.state.sprite_size = 80

  args.state.inventory_border.w  = args.state.sprite_size * 10
  args.state.inventory_border.h  = args.state.sprite_size * 3
  args.state.inventory_border.x  = 10
  args.state.inventory_border.y  = 710 - args.state.inventory_border.h

  # define the borders for where the crafting area is located
  # the crafting area is below the inventory area
  # the number 80 is the size of all the sprites, so that is what is being
  # used to decide the with and height
  args.state.craft_border.x =  10
  args.state.craft_border.y = 220
  args.state.craft_border.w = args.state.sprite_size * 3
  args.state.craft_border.h = args.state.sprite_size * 3

  # define the area where results are located
  # the crafting result is to the right of the craft area
  args.state.result_border.x =  10 + args.state.sprite_size * 3 + args.state.sprite_size
  args.state.result_border.y = 220 + args.state.sprite_size
  args.state.result_border.w = args.state.sprite_size
  args.state.result_border.h = args.state.sprite_size

  # initialize items for the first time if they are nil
  # you start with 15 wood, 1 chest, and 5 plank
  # Ruby has built in syntax for dictionaries (they look a lot like json objects).
  # Ruby also has a special type called a Symbol denoted with a : followed by a word.
  # Symbols are nice because they remove the need for magic strings.
  if !args.state.items
    args.state.items = [
      {
        id: :wood, # :wood is a Symbol, this is better than using "wood" for the id
        quantity: 15,
        path: 'sprites/wood.png',
        location: :inventory,
        ordinal_x: 0, ordinal_y: 0
      },
      {
        id: :chest,
        quantity: 1,
        path: 'sprites/chest.png',
        location: :inventory,
        ordinal_x: 1, ordinal_y: 0
      },
      {
        id: :plank,
        quantity: 5,
        path: 'sprites/plank.png',
        location: :inventory,
        ordinal_x: 2, ordinal_y: 0
      },
    ]

    # after initializing the oridinal positions, derive the pixel
    # locations assuming that the width and height are 80
    args.state.items.each { |item| set_inventory_position args, item }
  end

  # define all the oridinal positions of the inventory slots
  if !args.state.inventory_area
    args.state.inventory_area = [
      { ordinal_x: 0,  ordinal_y: 0 },
      { ordinal_x: 1,  ordinal_y: 0 },
      { ordinal_x: 2,  ordinal_y: 0 },
      { ordinal_x: 3,  ordinal_y: 0 },
      { ordinal_x: 4,  ordinal_y: 0 },
      { ordinal_x: 5,  ordinal_y: 0 },
      { ordinal_x: 6,  ordinal_y: 0 },
      { ordinal_x: 7,  ordinal_y: 0 },
      { ordinal_x: 8,  ordinal_y: 0 },
      { ordinal_x: 9,  ordinal_y: 0 },
      { ordinal_x: 0,  ordinal_y: 1 },
      { ordinal_x: 1,  ordinal_y: 1 },
      { ordinal_x: 2,  ordinal_y: 1 },
      { ordinal_x: 3,  ordinal_y: 1 },
      { ordinal_x: 4,  ordinal_y: 1 },
      { ordinal_x: 5,  ordinal_y: 1 },
      { ordinal_x: 6,  ordinal_y: 1 },
      { ordinal_x: 7,  ordinal_y: 1 },
      { ordinal_x: 8,  ordinal_y: 1 },
      { ordinal_x: 9,  ordinal_y: 1 },
      { ordinal_x: 0,  ordinal_y: 2 },
      { ordinal_x: 1,  ordinal_y: 2 },
      { ordinal_x: 2,  ordinal_y: 2 },
      { ordinal_x: 3,  ordinal_y: 2 },
      { ordinal_x: 4,  ordinal_y: 2 },
      { ordinal_x: 5,  ordinal_y: 2 },
      { ordinal_x: 6,  ordinal_y: 2 },
      { ordinal_x: 7,  ordinal_y: 2 },
      { ordinal_x: 8,  ordinal_y: 2 },
      { ordinal_x: 9,  ordinal_y: 2 },
    ]

    # after initializing the oridinal positions, derive the pixel
    # locations assuming that the width and height are 80
    args.state.inventory_area.each { |i| set_inventory_position args, i }

    # if you want to see the result you can use the Ruby function called "puts".
    # Uncomment this line to see the value.
    # puts args.state.inventory_area

    # You can see all things written via puts in DragonRuby's Console, or under logs/log.txt.
    # To bring up DragonRuby's Console, press the ~ key within the game.
  end

  # define all the oridinal positions of the craft slots
  if !args.state.craft_area
    args.state.craft_area = [
      { ordinal_x: 0, ordinal_y: 0 },
      { ordinal_x: 0, ordinal_y: 1 },
      { ordinal_x: 0, ordinal_y: 2 },
      { ordinal_x: 1, ordinal_y: 0 },
      { ordinal_x: 1, ordinal_y: 1 },
      { ordinal_x: 1, ordinal_y: 2 },
      { ordinal_x: 2, ordinal_y: 0 },
      { ordinal_x: 2, ordinal_y: 1 },
      { ordinal_x: 2, ordinal_y: 2 },
    ]

    # after initializing the oridinal positions, derive the pixel
    # locations assuming that the width and height are 80
    args.state.craft_area.each { |c| set_craft_position args, c }
  end
end


def render args
  # for the results area, create a sprite that show its boundaries
  args.outputs.primitives << { x: args.state.result_border.x,
                               y: args.state.result_border.y,
                               w: args.state.result_border.w,
                               h: args.state.result_border.h,
                               path: 'sprites/border-black.png' }

  # for each inventory spot, create a sprite
  # args.outputs.primitives is how DragonRuby performs a render.
  # Adding a single hash or multiple hashes to this array will tell
  # DragonRuby to render those primitives on that frame.

  # The .map function on Array is used instead of any kind of looping.
  # .map returns a new object for every object within an Array.
  args.outputs.primitives << args.state.inventory_area.map do |a|
    { x: a.x, y: a.y, w: a.w, h: a.h, path: 'sprites/border-black.png' }
  end

  # for each craft spot, create a sprite
  args.outputs.primitives << args.state.craft_area.map do |a|
    { x: a.x, y: a.y, w: a.w, h: a.h, path: 'sprites/border-black.png' }
  end

  # after the borders have been rendered, render the
  # items within those slots (and allow for highlighting)
  # if an item isn't currently being held
  allow_inventory_highlighting = !args.state.held_item

  # go through each item and render them
  # use Array's find_all method to remove any items that are currently being held
  args.state.items.find_all { |item| item[:location] != :held }.map do |item|
    # if an item is currently being held, don't render it in it's spot within the
    # inventory or craft area (this is handled via the find_all method).

    # the item_prefab returns a hash containing all the visual components of an item.
    # the main sprite, the black background, the quantity text, and a hover indication
    # if the mouse is currently hovering over the item.
    args.outputs.primitives << item_prefab(args, item, allow_inventory_highlighting, args.inputs.mouse)
  end

  # The last thing we want to render is the item currently being held.
  args.outputs.primitives << item_prefab(args, args.state.held_item, allow_inventory_highlighting, args.inputs.mouse)

  args.outputs.primitives << args.state.click_ripples

  # render a mouse cursor since we have the OS cursor hidden
  args.outputs.primitives << { x: args.inputs.mouse.x - 5, y: args.inputs.mouse.y - 5, w: 10, h: 10, path: 'sprites/circle-gray.png', a: 128 }
end

# Alrighty! This is where all the fun happens
def input args
  # if the mouse is clicked and not item is currently being held
  # args.state.held_item is nil when the game starts.
  # If the player clicks, the property args.inputs.mouse.click will
  # be a non nil value, we don't want to process any of the code here
  # if the mouse hasn't been clicked
  return if !args.inputs.mouse.click

  # if a click occurred, add a ripple to the ripple queue
  args.state.click_ripples << { x: args.inputs.mouse.x - 5, y: args.inputs.mouse.y - 5, w: 10, h: 10, path: 'sprites/circle-gray.png', a: 128 }

  # if the mouse has been clicked, and no item is currently held...
  if !args.state.held_item
    # see if any of the items intersect the pointer using the inside_rect? method
    # the find method will either return the first object that returns true
    # for the match clause, or it'll return nil if nothing matches the match clause
    found = args.state.items.find do |item|
      # for each item in args.state.items, run the following boolean check
      args.inputs.mouse.click.point.inside_rect?(item)
    end

    # if an item intersects the mouse pointer, then set the item's location to :held and
    # set args.state.held_item to the item for later reference
    if found
      args.state.held_item = found
      found[:location] = :held
    end

  # if the mouse is clicked and an item is currently beign held....
  elsif args.state.held_item
    # determine if a slot within the craft area was clicked
    craft_area = args.state.craft_area.find { |a| args.inputs.mouse.click.point.inside_rect? a }

    # also determine if a slot within the inventory area was clicked
    inventory_area = args.state.inventory_area.find { |a| args.inputs.mouse.click.point.inside_rect? a }

    # if the click was within a craft area
    if craft_area
      # check to see if an item is already there and ignore the click if an item is found
      # item_at_craft_slot is a helper method that returns an item or nil for a given oridinal
      # position
      item_already_there = item_at_craft_slot args, craft_area[:ordinal_x], craft_area[:ordinal_y]

      # if an item *doesn't* exist in the craft area
      if !item_already_there
        # if the quantity they are currently holding is greater than 1
        if args.state.held_item[:quantity] > 1
          # remove one item (creating a seperate item of the same type), and place it
          # at the oridinal position and location of the craft area
          # the .merge method on Hash creates a new Hash, but updates any values
          # passed as arguments to merge
          new_item = args.state.held_item.merge(quantity: 1,
                                                location: :craft,
                                                ordinal_x: craft_area[:ordinal_x],
                                                ordinal_y: craft_area[:ordinal_y])

          # after the item is crated, place it into the args.state.items collection
          args.state.items << new_item

          # then subtract one from the held item
          args.state.held_item[:quantity] -= 1

        # if the craft area is available and there is only one item being held
        elsif args.state.held_item[:quantity] == 1
          # instead of creating any new items just set the location of the held item
          # to the oridinal position of the craft area, and then nil out the
          # held item state so that a new item can be picked up
          args.state.held_item[:location] = :craft
          args.state.held_item[:ordinal_x] = craft_area[:ordinal_x]
          args.state.held_item[:ordinal_y] = craft_area[:ordinal_y]
          args.state.held_item = nil
        end
      end

    # if the selected area is an inventory area (as opposed to within the craft area)
    elsif inventory_area

      # check to see if there is already an item in that inventory slot
      # the item_at_inventory_slot helper method returns an item or nil
      item_already_there = item_at_inventory_slot args, inventory_area[:ordinal_x], inventory_area[:ordinal_y]

      # if there is already an item there, and the item types/id match
      if item_already_there && item_already_there[:id] == args.state.held_item[:id]
        # then merge the item quantities
        held_quantity = args.state.held_item[:quantity]
        item_already_there[:quantity] += held_quantity

        # remove the item being held from the items collection (since it's quantity is now 0)
        args.state.items.reject! { |i| i[:location] == :held }

        # nil out the held_item so a new item can be picked up
        args.state.held_item = nil

      # if there currently isn't an item there, then put the held item in the slot
      elsif !item_already_there
        args.state.held_item[:location] = :inventory
        args.state.held_item[:ordinal_x] = inventory_area[:ordinal_x]
        args.state.held_item[:ordinal_y] = inventory_area[:ordinal_y]

        # nil out the held_item so a new item can be picked up
        args.state.held_item = nil
      end
    end
  end
end

# the calc method is executed after input
def calc args
  # make sure that the real position of the inventory
  # items are updated every frame to ensure that they
  # are placed correctly given their location and oridinal positions
  # instead of using .map, here we use .each (since we are not returning a new item and just updating the items in place)
  args.state.items.each do |item|
    # based on the location of the item, invoke the correct pixel conversion method
    if item[:location] == :inventory
      set_inventory_position args, item
    elsif item[:location] == :craft
      set_craft_position args, item
    elsif item[:location] == :held
      # if the item is held, center the item around the mouse pointer
      args.state.held_item.x = args.inputs.mouse.x - args.state.held_item.w.half
      args.state.held_item.y = args.inputs.mouse.y - args.state.held_item.h.half
    end
  end

  # for each hash/sprite in the click ripples queue,
  # expand its size by 20 percent and decrease its alpha
  # by 10.
  args.state.click_ripples.each do |ripple|
    delta_w = ripple.w * 1.2 - ripple.w
    delta_h = ripple.h * 1.2 - ripple.h
    ripple.x -= delta_w.half
    ripple.y -= delta_h.half
    ripple.w += delta_w
    ripple.h += delta_h
    ripple.a -= 10
  end

  # remove any items from the collection where the alpha value is less than equal to
  # zero using the reject! method (reject with an exclamation point at the end changes the
  # array value in place, while reject without the exclamation point returns a new array).
  args.state.click_ripples.reject! { |ripple| ripple.a <= 0 }
end

# helper function for finding an item at a craft slot
def item_at_craft_slot args, ordinal_x, ordinal_y
  args.state.items.find { |i| i[:location] == :craft && i[:ordinal_x] == ordinal_x && i[:ordinal_y] == ordinal_y }
end

# helper function for finding an item at an inventory slot
def item_at_inventory_slot args, ordinal_x, ordinal_y
  args.state.items.find { |i| i[:location] == :inventory && i[:ordinal_x] == ordinal_x && i[:ordinal_y] == ordinal_y }
end

# helper function that creates a visual representation of an item
def item_prefab args, item, should_highlight, mouse
  return nil unless item

  overlay = nil

  x = item.x
  y = item.y
  w = item.w
  h = item.h

  if should_highlight && mouse.point.inside_rect?(item)
    overlay = { x: x, y: y, w: w, h: h, path: "sprites/square-blue.png", a: 130, }
  end

  [
    # sprites are hashes with a path property, this is the main sprite
    { x: x,      y: y, w: args.state.sprite_size, h: args.state.sprite_size, path: item[:path], },

    # this represents the black area in the bottom right corner of the main sprite so that the
    # quantity is visible
    { x: x + 55, y: y, w: 25, h: 25, path: "sprites/square-black.png", }, # sprites are hashes with a path property

    # labels are hashes with a text property
    { x: x + 56, y: y + 22, text: "#{item[:quantity]}", r: 255, g: 255, b: 255, },

    # this is the mouse overlay, if the overlay isn't applicable, then this value will be nil (nil values will not be rendered)
    overlay
  ]
end

# helper function for deriving the position of an item within inventory
def set_inventory_position args, item
  item.x = args.state.inventory_border.x + item[:ordinal_x] * 80
  item.y = (args.state.inventory_border.y + args.state.inventory_border.h - 80) - item[:ordinal_y] * 80
  item.w = 80
  item.h = 80
end

# helper function for deriving the position of an item within the craft area
def set_craft_position args, item
  item.x = args.state.craft_border.x + item[:ordinal_x] * 80
  item.y = (args.state.craft_border.y + args.state.inventory_border.h - 80) - item[:ordinal_y] * 80
  item.w = 80
  item.h = 80
end

# Any lines outside of a function will be executed when the file is reloaded.
# So every time you save main.rb, the game will be reset.
# Comment out the line below if you don't want this to happen.
$gtk.reset

    Farming Game Starting Point - main.rb link

    # ./samples/99_genre_crafting/farming_game_starting_point/app/main.rb
def tick args
  args.state.tile_size     = 80
  args.state.player_speed  = 4
  args.state.player      ||= tile(args, 7, 3, 0, 128, 180)
  generate_map args
  #press j to plant a green onion
  if args.inputs.keyboard.j
  #change this part you can change what you want to plant
   args.state.walls << tile(args, ((args.state.player.x+80)/args.state.tile_size), ((args.state.player.y)/args.state.tile_size), 255, 255, 255)
   args.state.plants << tile(args, ((args.state.player.x+80)/args.state.tile_size), ((args.state.player.y+80)/args.state.tile_size), 0, 160, 0)
  end
  # Adds walls, background, and player to args.outputs.solids so they appear on screen
  args.outputs.solids << [0,0,1280,720, 237,189,101]
  args.outputs.sprites << [0, 0, 1280, 720, 'sprites/background.png']
  args.outputs.solids << args.state.walls
  args.outputs.solids << args.state.player
  args.outputs.solids << args.state.plants
  args.outputs.labels << [320, 640, "press J to plant", 3, 1, 255, 0, 0, 200]

  move_player args, -1,  0 if args.inputs.keyboard.left # x position decreases by 1 if left key is pressed
  move_player args,  1,  0 if args.inputs.keyboard.right # x position increases by 1 if right key is pressed
  move_player args,  0,  1 if args.inputs.keyboard.up # y position increases by 1 if up is pressed
  move_player args,  0, -1 if args.inputs.keyboard.down # y position decreases by 1 if down is pressed
end

# Sets position, size, and color of the tile
def tile args, x, y, *color
  [x * args.state.tile_size, # sets definition for array using method parameters
   y * args.state.tile_size, # multiplying by tile_size sets x and y to correct position using pixel values
   args.state.tile_size,
   args.state.tile_size,
   *color]
end

# Creates map by adding tiles to the wall, as well as a goal (that the player needs to reach)
def generate_map args
  return if args.state.area

  # Creates the area of the map. There are 9 rows running horizontally across the screen
  # and 16 columns running vertically on the screen. Any spot with a "1" is not
  # open for the player to move into (and is green), and any spot with a "0" is available
  # for the player to move in.
  args.state.area = [
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 ],
  ].reverse # reverses the order of the area collection

  # By reversing the order, the way that the area appears above is how it appears
  # on the screen in the game. If we did not reverse, the map would appear inverted.

  #The wall starts off with no tiles.
  args.state.walls = []
  args.state.plants = []

  # If v is 1, a green tile is added to args.state.walls.
  # If v is 2, a black tile is created as the goal.
  args.state.area.map_2d do |y, x, v|
    if    v == 1
      args.state.walls << tile(args, x, y, 255, 160, 156) # green tile
    end
  end
end

# Allows the player to move their box around the screen
def move_player args, *vector
  box = args.state.player.shift_rect(vector) # box is able to move at an angle

  # If the player's box hits a wall, it is not able to move further in that direction
  return if args.state.walls
                .any_intersect_rect?(box)

  # Player's box is able to move at angles (not just the four general directions) fast
  args.state.player =
    args.state.player
        .shift_rect(vector.x * args.state.player_speed, # if we don't multiply by speed, then
                    vector.y * args.state.player_speed) # the box will move extremely slow
end

    Farming Game Starting Point - repl.rb link

    # ./samples/99_genre_crafting/farming_game_starting_point/app/repl.rb
# ===============================================================
# Welcome to repl.rb
# ===============================================================
# You can experiement with code within this file. Code in this
# file is only executed when you save (and only excecuted ONCE).
# ===============================================================

# ===============================================================
# REMOVE the "x" from the word "xrepl" and save the file to RUN
# the code in between the do/end block delimiters.
# ===============================================================

# ===============================================================
# ADD the "x" to the word "repl" (make it xrepl) and save the
# file to IGNORE the code in between the do/end block delimiters.
# ===============================================================

# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  puts "The result of 1 + 2 is: #{1 + 2}"
end

# ====================================================================================
# Ruby Crash Course:
# Strings, Numeric, Booleans, Conditionals, Looping, Enumerables, Arrays
# ====================================================================================

# ====================================================================================
#  Strings
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  message = "Hello World"
  puts "The value of message is: " + message
  puts "Any value can be interpolated within a string using \#{}."
  puts "Interpolated message: #{message}."
  puts 'This #{message} is not interpolated because the string uses single quotes.'
end

# ====================================================================================
#  Numerics
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  a = 10
  puts "The value of a is: #{a}"
  puts "a + 1 is: #{a + 1}"
  puts "a / 3 is: #{a / 3}"
end

# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  b = 10.12
  puts "The value of b is: #{b}"
  puts "b + 1 is: #{b + 1}"
  puts "b as an integer is: #{b.to_i}"
  puts ''
end

# ====================================================================================
#  Booleans
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  c = 30
  puts "The value of c is #{c}."

  if c
    puts "This if statement ran because c is truthy."
  end
end

# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  d = false
  puts "The value of d is #{d}."

  if !d
    puts "This if statement ran because d is falsey, using the not operator (!) makes d evaluate to true."
  end

  e = nil
  puts "Nil is also considered falsey. The value of e is: #{e}."

  if !e
    puts "This if statement ran because e is nil (a falsey value)."
  end
end

# ====================================================================================
#  Conditionals
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  i_am_true  = true
  i_am_nil   = nil
  i_am_false = false
  i_am_hi    = "hi"

  puts "======== if statement"
  i_am_one = 1
  if i_am_one
    puts "This was printed because i_am_one is truthy."
  end

  puts "======== if/else statement"
  if i_am_false
    puts "This will NOT get printed because i_am_false is false."
  else
    puts "This was printed because i_am_false is false."
  end

  puts "======== if/elsif/else statement"
  if i_am_false
    puts "This will NOT get printed because i_am_false is false."
  elsif i_am_true
    puts "This was printed because i_am_true is true."
  else
    puts "This will NOT get printed i_am_true was true."
  end

  puts "======== case statement "
  i_am_one = 1
  case i_am_one
  when 10
    puts "case equaled: 10"
  when 9
    puts "case equaled: 9"
  when 5
    puts "case equaled: 5"
  when 1
    puts "case equaled: 1"
  else
    puts "Value wasn't cased."
  end

  puts "======== different types of comparisons"
  if 4 == 4
    puts "equal (4 == 4)"
  end

  if 4 != 3
    puts "not equal (4 != 3)"
  end

  if 3 < 4
    puts "less than (3 < 4)"
  end

  if 4 > 3
    puts "greater than (4 > 3)"
  end

  if ((4 > 3) || (3 < 4) || false)
    puts "or statement ((4 > 3) || (3 < 4) || false)"
  end

  if ((4 > 3) && (3 < 4))
    puts "and statement ((4 > 3) && (3 < 4))"
  end
end

# ====================================================================================
# Looping
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  puts "======== times block"
  3.times do |i|
    puts i
  end
  puts "======== range block exclusive"
  (0...3).each do |i|
    puts i
  end
  puts "======== range block inclusive"
  (0..3).each do |i|
    puts i
  end
end

# ====================================================================================
#  Enumerables
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  puts "======== array each"
  colors = ["red", "blue", "yellow"]
  colors.each do |color|
    puts color
  end

  puts '======== array each_with_index'
  colors = ["red", "blue", "yellow"]
  colors.each_with_index do |color, i|
    puts "#{color} at index #{i}"
  end
end

# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  puts "======== single parameter function"
  def add_one_to n
    n + 5
  end

  puts add_one_to(3)

  puts "======== function with default value"
  def function_with_default_value v = 10
    v * 10
  end

  puts "passing three: #{function_with_default_value(3)}"
  puts "passing nil: #{function_with_default_value}"

  puts "======== Or Equal (||=) operator for nil values"
  def function_with_nil_default_with_local a = nil
    result   = a
    result ||= "or equal operator was exected and set a default value"
  end

  puts "passing 'hi': #{function_with_nil_default_with_local 'hi'}"
  puts "passing nil: #{function_with_nil_default_with_local}"
end

# ====================================================================================
#  Arrays
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  puts "======== Create an array with the numbers 1 to 10."
  one_to_ten = (1..10).to_a
  puts one_to_ten

  puts "======== Create a new array that only contains even numbers from the previous array."
  one_to_ten = (1..10).to_a
  evens = one_to_ten.find_all do |number|
    number % 2 == 0
  end
  puts evens

  puts "======== Create a new array that rejects odd numbers."
  one_to_ten = (1..10).to_a
  also_even = one_to_ten.reject do |number|
    number % 2 != 0
  end
  puts also_even

  puts "======== Create an array that doubles every number."
  one_to_ten = (1..10).to_a
  doubled = one_to_ten.map do |number|
    number * 2
  end
  puts doubled

  puts "======== Create an array that selects only odd numbers and then multiply those by 10."
  one_to_ten = (1..10).to_a
  odd_doubled = one_to_ten.find_all do |number|
    number % 2 != 0
  end.map do |odd_number|
    odd_number * 10
  end
  puts odd_doubled

  puts "======== All combination of numbers 1 to 10."
  one_to_ten = (1..10).to_a
  all_combinations = one_to_ten.product(one_to_ten)
  puts all_combinations

  puts "======== All uniq combinations of numbers. For example: [1, 2] is the same as [2, 1]."
  one_to_ten = (1..10).to_a
  uniq_combinations =
    one_to_ten.product(one_to_ten)
      .map do |unsorted_number|
    unsorted_number.sort
  end.uniq
  puts uniq_combinations
end

# ====================================================================================
#  Advanced Arrays
# ====================================================================================
# Remove the x from xrepl to run the code. Add the x back to ignore to code.
xrepl do
  puts "======== All unique Pythagorean Triples between 1 and 40 sorted by area of the triangle."

  one_to_hundred = (1..40).to_a
  triples =
    one_to_hundred.product(one_to_hundred).map do |width, height|
    [width, height, Math.sqrt(width ** 2 + height ** 2)]
  end.find_all do |_, _, hypotenuse|
    hypotenuse.to_i == hypotenuse
  end.map do |triangle|
    triangle.map(&:to_i)
  end.uniq do |triangle|
    triangle.sort
  end.map do |width, height, hypotenuse|
    [width, height, hypotenuse, (width * height) / 2]
  end.sort_by do |_, _, _, area|
    area
  end

  triples.each do |width, height, hypotenuse, area|
    puts "(#{width}, #{height}, #{hypotenuse}) = #{area}"
  end
end

    Genre Dev Tools link

    Add Buttons To Console - main.rb link

    # ./samples/99_genre_dev_tools/add_buttons_to_console/app/main.rb
# You can customize the buttons that show up in the Console.
class GTK::Console::Menu
  # STEP 1: Override the custom_buttons function.
  def custom_buttons
    [
      (button id: :yay,
              # row for button
              row: 3,
              # column for button
              col: 10,
              # text
              text: "I AM CUSTOM",
              # when clicked call the custom_button_clicked function
              method: :custom_button_clicked),

      (button id: :yay,
              # row for button
              row: 3,
              # column for button
              col: 9,
              # text
              text: "CUSTOM ALSO",
              # when clicked call the custom_button_also_clicked function
              method: :custom_button_also_clicked)
    ]
  end

  # STEP 2: Define the function that should be called.
  def custom_button_clicked
    log "* INFO: I AM CUSTOM was clicked!"
  end

  def custom_button_also_clicked
    log "* INFO: Custom Button Clicked at #{Kernel.global_tick_count}!"

    all_buttons_as_string = $gtk.console.menu.buttons.map do |b|
      <<-S.strip
** id: #{b[:id]}
:PROPERTIES:
:id:     :#{b[:id]}
:method: :#{b[:method]}
:text:   #{b[:text]}
:END:
S
    end.join("\n")

    log <<-S
* INFO: Here are all the buttons:
#{all_buttons_as_string}
S
  end
end

def tick args
  args.outputs.labels << [args.grid.center.x, args.grid.center.y,
                          "Open the DragonRuby Console to see the custom menu items.",
                          0, 1]
end

    Animation Creator Starting Point - main.rb link

    # ./samples/99_genre_dev_tools/animation_creator_starting_point/app/main.rb
class OneBitLowrezPaint
  attr_gtk

  def tick
    outputs.background_color = [0, 0, 0]
    defaults
    render_instructions
    render_canvas
    render_buttons_frame_selection
    render_animation_frame_thumbnails
    render_animation
    input_mouse_click
    input_keyboard
    calc_auto_export
    calc_buttons_frame_selection
    calc_animation_frames
    process_queue_create_sprite
    process_queue_reset_sprite
    process_queue_update_rt_animation_frame
  end

  def defaults
    state.animation_frames_per_second = 12
    queues.create_sprite ||= []
    queues.reset_sprite ||= []
    queues.update_rt_animation_frame ||= []

    if !state.animation_frames
      state.animation_frames ||= []
      add_animation_frame_to_end
    end

    state.last_mouse_down ||= 0
    state.last_mouse_up   ||= 0

    state.buttons_frame_selection.left = 10
    state.buttons_frame_selection.top  = grid.top - 10
    state.buttons_frame_selection.size = 20
    state.buttons_frame_selection.items ||= []

    defaults_canvas_sprite

    state.edit_mode ||= :drawing
  end

  def defaults_canvas_sprite
    rt_canvas.size   = 16
    rt_canvas.zoom   = 30
    rt_canvas.width  = rt_canvas.size * rt_canvas.zoom
    rt_canvas.height = rt_canvas.size * rt_canvas.zoom
    rt_canvas.sprite = { x: 0,
                         y: 0,
                         w: rt_canvas.width,
                         h: rt_canvas.height,
                         path: :rt_canvas }.center_inside_rect(x: 0, y: 0, w: 640, h: 720)

    return unless state.tick_count == 1

    outputs[:rt_canvas].transient!
    outputs[:rt_canvas].width      = rt_canvas.width
    outputs[:rt_canvas].height     = rt_canvas.height
    outputs[:rt_canvas].sprites   << (rt_canvas.size + 1).map_with_index do |x|
      (rt_canvas.size + 1).map_with_index do |y|
        path = 'sprites/square-white.png'
        path = 'sprites/square-blue.png' if x == 7 || x == 8
        { x: x * rt_canvas.zoom,
          y: y * rt_canvas.zoom,
          w: rt_canvas.zoom,
          h: rt_canvas.zoom,
          path: path,
          a: 50 }
      end
    end
  end

  def render_instructions
    instructions = [
      "* Hotkeys:",
      "- d: hold to erase, release to draw.",
      "- a: add frame.",
      "- c: copy frame.",
      "- v: paste frame.",
      "- x: delete frame.",
      "- b: go to previous frame.",
      "- f: go to next frame.",
      "- w: save to ./canvas directory.",
      "- l: load from ./canvas."
    ]

    instructions.each.with_index do |l, i|
      outputs.labels << { x: 840, y: 500 - (i * 20), text: "#{l}",
                          r: 180, g: 180, b: 180, size_enum: 0 }
    end
  end

  def render_canvas
    return if state.tick_count.zero?
    outputs.sprites << rt_canvas.sprite
  end

  def render_buttons_frame_selection
    args.outputs.primitives << state.buttons_frame_selection.items.map_with_index do |b, i|
      label = { x: b.x + state.buttons_frame_selection.size.half,
                y: b.y,
                text: "#{i + 1}", r: 180, g: 180, b: 180,
                size_enum: -4, alignment_enum: 1 }.label!

      selection_border = b.merge(r: 40, g: 40, b: 40).border!

      if i == state.animation_frames_selected_index
        selection_border = b.merge(r: 40, g: 230, b: 200).border!
      end

      [selection_border, label]
    end
  end

  def render_animation_frame_thumbnails
    return if state.tick_count.zero?

    outputs[:current_animation_frame].transient!
    outputs[:current_animation_frame].width   = rt_canvas.size
    outputs[:current_animation_frame].height  = rt_canvas.size
    outputs[:current_animation_frame].solids <<  selected_animation_frame[:pixels].map_with_index do |f, i|
      { x: f.x,
        y: f.y,
        w: 1,
        h: 1, r: 255, g: 255, b: 255 }
    end

    outputs.sprites << rt_canvas.sprite.merge(path: :current_animation_frame)

    state.animation_frames.map_with_index do |animation_frame, animation_frame_index|
      outputs.sprites << state.buttons_frame_selection[:items][animation_frame_index][:inner_rect]
                              .merge(path: animation_frame[:rt_name])
    end
  end

  def render_animation
    sprite_index = 0.frame_index count: state.animation_frames.length,
                                 hold_for: 60 / state.animation_frames_per_second,
                                 repeat: true

    args.outputs.sprites << { x: 700 - 8,
                              y: 120,
                              w: 16,
                              h: 16,
                              path: (sprite_path sprite_index) }

    args.outputs.sprites << { x: 700 - 16,
                              y: 230,
                              w: 32,
                              h: 32,
                              path: (sprite_path sprite_index) }

    args.outputs.sprites << { x: 700 - 32,
                              y: 360,
                              w: 64,
                              h: 64,
                              path: (sprite_path sprite_index) }

    args.outputs.sprites << { x: 700 - 64,
                              y: 520,
                              w: 128,
                              h: 128,
                              path: (sprite_path sprite_index) }
  end

  def input_mouse_click
    if inputs.mouse.up
      state.last_mouse_up = state.tick_count
    elsif inputs.mouse.moved && user_is_editing?
      edit_current_animation_frame inputs.mouse.point
    end

    return unless inputs.mouse.click

    clicked_frame_button = state.buttons_frame_selection.items.find do |b|
      inputs.mouse.point.inside_rect? b
    end

    if (clicked_frame_button)
      state.animation_frames_selected_index = clicked_frame_button[:index]
    end

    if (inputs.mouse.point.inside_rect? rt_canvas.sprite)
      state.last_mouse_down = state.tick_count
      edit_current_animation_frame inputs.mouse.point
    end
  end

  def input_keyboard
    # w to save
    if inputs.keyboard.key_down.w
      t = Time.now
      state.save_description = "Time: #{t} (#{t.to_i})"
      gtk.serialize_state 'canvas/state.txt', state
      gtk.serialize_state "tmp/canvas_backups/#{t.to_i}/state.txt", state
      animation_frames.each_with_index do |animation_frame, i|
        queues.update_rt_animation_frame << { index: i,
                                              at: state.tick_count + i,
                                              queue_sprite_creation: true }
        queues.create_sprite << { index: i,
                                  at: state.tick_count + animation_frames.length + i,
                                  path_override: "tmp/canvas_backups/#{t.to_i}/sprite-#{i}.png" }
      end
      gtk.notify! "Canvas saved."
    end

    # l to load
    if inputs.keyboard.key_down.l
      args.state = gtk.deserialize_state 'canvas/state.txt'
      animation_frames.each_with_index do |a, i|
        queues.update_rt_animation_frame << { index: i,
                                              at: state.tick_count + i,
                                              queue_sprite_creation: true }
      end
      gtk.notify! "Canvas loaded."
    end

    # d to go into delete mode, release to paint
    if inputs.keyboard.key_held.d
      state.edit_mode = :erasing
      gtk.notify! "Erasing." if inputs.keyboard.key_held.d == (state.tick_count - 1)
    elsif inputs.keyboard.key_up.d
      state.edit_mode = :drawing
      gtk.notify! "Drawing."
    end

    # a to add a frame to the end
    if inputs.keyboard.key_down.a
      queues.create_sprite << { index: state.animation_frames_selected_index,
                                at: state.tick_count }
      queues.create_sprite << { index: state.animation_frames_selected_index + 1,
                                at: state.tick_count }
      add_animation_frame_to_end
      gtk.notify! "Frame added to end."
    end

    # c or t to copy
    if (inputs.keyboard.key_down.c || inputs.keyboard.key_down.t)
      state.clipboard = [selected_animation_frame[:pixels]].flatten
      gtk.notify! "Current frame copied."
    end

    # v or q to paste
    if (inputs.keyboard.key_down.v || inputs.keyboard.key_down.q) && state.clipboard
      selected_animation_frame[:pixels] = [state.clipboard].flatten
      queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
                                            at: state.tick_count,
                                            queue_sprite_creation: true }
      gtk.notify! "Pasted."
    end

    # f to go forward/next frame
    if (inputs.keyboard.key_down.f)
      if (state.animation_frames_selected_index == (state.animation_frames.length - 1))
        state.animation_frames_selected_index = 0
      else
        state.animation_frames_selected_index += 1
      end
      gtk.notify! "Next frame."
    end

    # b to go back/previous frame
    if (inputs.keyboard.key_down.b)
      if (state.animation_frames_selected_index == 0)
        state.animation_frames_selected_index = state.animation_frames.length - 1
      else
        state.animation_frames_selected_index -= 1
      end
      gtk.notify! "Previous frame."
    end

    # x to delete frame
    if (inputs.keyboard.key_down.x) && animation_frames.length > 1
      state.clipboard = selected_animation_frame[:pixels]
      state.animation_frames = animation_frames.find_all { |v| v[:index] != state.animation_frames_selected_index }
      if state.animation_frames_selected_index >= state.animation_frames.length
        state.animation_frames_selected_index = state.animation_frames.length - 1
      end
      gtk.notify! "Frame deleted."
    end
  end

  def calc_auto_export
    return if user_is_editing?
    return if state.last_mouse_up.elapsed_time != 30
    # auto export current animation frame if there is no editing for 30 ticks
    queues.create_sprite << { index: state.animation_frames_selected_index,
                              at: state.tick_count }
  end

  def calc_buttons_frame_selection
    state.buttons_frame_selection.items = animation_frames.length.map_with_index do |i|
      { x: state.buttons_frame_selection.left + i * state.buttons_frame_selection.size,
        y: state.buttons_frame_selection.top - state.buttons_frame_selection.size,
        inner_rect: {
          x: (state.buttons_frame_selection.left + 2) + i * state.buttons_frame_selection.size,
          y: (state.buttons_frame_selection.top - state.buttons_frame_selection.size + 2),
          w: 16,
          h: 16,
        },
        w: state.buttons_frame_selection.size,
        h: state.buttons_frame_selection.size,
        index: i }
    end
  end

  def calc_animation_frames
    animation_frames.each_with_index do |animation_frame, i|
      animation_frame[:index] = i
      animation_frame[:rt_name] = "animation_frame_#{i}"
    end
  end

  def process_queue_create_sprite
    sprites_to_create = queues.create_sprite
                              .find_all { |h| h[:at].elapsed? }

    queues.create_sprite = queues.create_sprite - sprites_to_create

    sprites_to_create.each do |h|
      export_animation_frame h[:index], h[:path_override]
    end
  end

  def process_queue_reset_sprite
    sprites_to_reset = queues.reset_sprite
                             .find_all { |h| h[:at].elapsed? }

    queues.reset_sprite -= sprites_to_reset

    sprites_to_reset.each { |h| gtk.reset_sprite (sprite_path h[:index]) }
  end

  def process_queue_update_rt_animation_frame
    animation_frames_to_update = queues.update_rt_animation_frame
                                       .find_all { |h| h[:at].elapsed? }

    queues.update_rt_animation_frame -= animation_frames_to_update

    animation_frames_to_update.each do |h|
      update_animation_frame_render_target animation_frames[h[:index]]

      if h[:queue_sprite_creation]
        queues.create_sprite << { index: h[:index],
                                  at: state.tick_count + 1 }
      end
    end
  end

  def update_animation_frame_render_target animation_frame
    return if !animation_frame

    outputs[animation_frame[:rt_name]].transient = true
    outputs[animation_frame[:rt_name]].width   = state.rt_canvas.size
    outputs[animation_frame[:rt_name]].height  = state.rt_canvas.size
    outputs[animation_frame[:rt_name]].solids << animation_frame[:pixels].map do |f|
      { x: f.x,
        y: f.y,
        w: 1,
        h: 1, r: 255, g: 255, b: 255 }
    end
  end

  def animation_frames
    state.animation_frames
  end

  def add_animation_frame_to_end
    animation_frames << {
      index: animation_frames.length,
      pixels: [],
      rt_name: "animation_frame_#{animation_frames.length}"
    }

    state.animation_frames_selected_index = (animation_frames.length - 1)
    queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
                                          at: state.tick_count,
                                          queue_sprite_creation: true }
  end

  def sprite_path i
    "canvas/sprite-#{i}.png"
  end

  def export_animation_frame i, path_override = nil
    return if !state.animation_frames[i]

    outputs.screenshots << state.buttons_frame_selection
                                .items[i][:inner_rect]
                                .merge(path: path_override || (sprite_path i))

    outputs.screenshots << state.buttons_frame_selection
                                .items[i][:inner_rect]
                                .merge(path: "tmp/sprite_backups/#{Time.now.to_i}-sprite-#{i}.png")

    queues.reset_sprite << { index: i, at: state.tick_count }
  end

  def selected_animation_frame
    state.animation_frames[state.animation_frames_selected_index]
  end

  def edit_current_animation_frame point
    draw_area_point = (to_draw_area point)
    if state.edit_mode == :drawing && (!selected_animation_frame[:pixels].include? draw_area_point)
      selected_animation_frame[:pixels] << draw_area_point
      queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
                                            at: state.tick_count,
                                            queue_sprite_creation: !user_is_editing? }
    elsif state.edit_mode == :erasing && (selected_animation_frame[:pixels].include? draw_area_point)
      selected_animation_frame[:pixels] = selected_animation_frame[:pixels].reject { |p| p == draw_area_point }
      queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
                                            at: state.tick_count,
                                            queue_sprite_creation: !user_is_editing? }
    end
  end

  def user_is_editing?
    state.last_mouse_down > state.last_mouse_up
  end

  def to_draw_area point
    x, y = point.x, point.y
    x -= rt_canvas.sprite.x
    y -= rt_canvas.sprite.y
    { x: x.idiv(rt_canvas.zoom),
      y: y.idiv(rt_canvas.zoom) }
  end

  def rt_canvas
    state.rt_canvas ||= state.new_entity(:rt_canvas)
  end

  def queues
    state.queues ||= state.new_entity(:queues)
  end
end

$game = OneBitLowrezPaint.new

def tick args
  $game.args = args
  $game.tick
end

# $gtk.reset

    Frame By Frame - main.rb link

    # ./samples/99_genre_dev_tools/frame_by_frame/app/main.rb
def tick args
  # create a tick count variant called clock
  # so I can manually control "tick_count"
  args.state.clock ||= 0

  # calc for frame by frame stepping
  calc_debug args

  # conditional calc of game
  calc_game args

  # always render game
  render_game args

  # increment clock
  if args.state.frame_by_frame
    if args.state.increment_frame > 0
      args.state.clock += 1
    end
  else
    args.state.clock += 1
  end
end

def calc_debug args
  # create an increment_frame counter for frame by frame
  # stepping
  args.state.increment_frame ||= 0
  args.state.increment_frame  -= 1

  # press l to increment by 30 frames or if any key is pressed
  if args.inputs.keyboard.key_down.l || args.inputs.keyboard.key_down.truthy_keys.length > 0
    args.state.increment_frame = 30
  end

  # enable disable frame by frame mode
  if args.inputs.keyboard.key_down.p
    if args.state.frame_by_frame == true
      args.state.frame_by_frame = false
    else
      args.state.frame_by_frame = true
      args.state.increment_frame = 0
    end
  end

  # press k to increment by one frame
  if args.inputs.keyboard.key_down.k
    args.state.increment_frame = 1
  end
end

def render_game args
  args.outputs.sprites << args.state.player
end

def calc_game args
  return if args.state.frame_by_frame && args.state.increment_frame < 0

  args.state.player ||= {
    x: 0,
    y: 360,
    w: 40,
    h: 40,
    anchor_x: 0.5,
    anchor_y: 0.5,
    path: :pixel,
    r: 0, g: 0, b: 255
  }

  args.state.player.x += 10
  args.state.player.y += args.inputs.up_down * 10

  if args.state.player.x > 1280
    args.state.player.x = 0
  end

  if args.state.player.y > 720
    args.state.player.y = 0
  elsif args.state.player.y < 0
    args.state.player.y = 720
  end
end

$gtk.reset

    Tile Editor Starting Point - main.rb link

    # ./samples/99_genre_dev_tools/tile_editor_starting_point/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - to_s: Returns a string representation of an object.
   For example, if we had
   500.to_s
   the string "500" would be returned.
   Similar to to_i, which returns an integer representation of an object.

 - Ceil: Returns an integer number greater than or equal to the original
   with no decimal.

 Reminders:

 - ARRAY#inside_rect?: Returns true or false depending on if the point is inside a rect.

 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - args.outputs.sprites: An array. The values generate a sprite.
   The parameters are [X, Y, WIDTH, HEIGHT, IMAGE PATH]
   For more information about sprites, go to mygame/documentation/05-sprites.md.

 - args.outputs.solids: An array. The values generate a solid.
   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.

 - args.outputs.lines: An array. The values generate a line.
   The parameters are [X1, Y1, X2, Y2, RED, GREEN, BLUE]
   For more information about lines, go to mygame/documentation/04-lines.md.

 - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
   In this sample app, new_entity is used to create a new button that clears the grid.
   (Remember, you can use state to define ANY property and it will be retained across frames.)

=end

# This sample app shows an empty grid that the user can paint in. There are different image tiles that
# the user can use to fill the grid, and the "Clear" button can be pressed to clear the grid boxes.

class TileEditor
  attr_accessor :inputs, :state, :outputs, :grid, :args

  # Runs all the methods necessary for the game to function properly.
  def tick
    defaults
    render
    check_click
    draw_buttons
  end

  # Sets default values
  # Initialization only happens in the first frame
  # NOTE: The values of some of these variables may seem confusingly large at first.
  # The gridSize is 1600 but it seems a lot smaller on the screen, for example.
  # But keep in mind that by using the "W", "A", "S", and "D" keys, you can
  # move the grid's view in all four directions for more grid spaces.
  def defaults
    state.tileCords      ||= []
    state.tileQuantity   ||= 6
    state.tileSize       ||= 50
    state.tileSelected   ||= 1
    state.tempX          ||= 50
    state.tempY          ||= 500
    state.speed          ||= 4
    state.centerX        ||= 4000
    state.centerY        ||= 4000
    state.originalCenter ||= [state.centerX, state.centerY]
    state.gridSize       ||= 1600
    state.lineQuantity   ||= 50
    state.increment      ||= state.gridSize / state.lineQuantity
    state.gridX          ||= []
    state.gridY          ||= []
    state.filled_squares ||= []
    state.grid_border    ||= [390, 140, 500, 500]

    get_grid unless state.tempX == 0 # calls get_grid in the first frame only
    determineTileCords unless state.tempX == 0 # calls determineTileCords in first frame
    state.tempX = 0 # sets tempX to 0; the two methods aren't called again
  end

  # Calculates the placement of lines or separators in the grid
  def get_grid
    curr_x = state.centerX - (state.gridSize / 2) # starts at left of grid
    deltaX = state.gridSize / state.lineQuantity # finds distance to place vertical lines evenly through width of grid
    (state.lineQuantity + 2).times do
      state.gridX << curr_x # adds curr_x to gridX collection
      curr_x += deltaX # increment curr_x by the distance between vertical lines
    end

    curr_y = state.centerY - (state.gridSize / 2) # starts at bottom of grid
    deltaY = state.gridSize / state.lineQuantity # finds distance to place horizontal lines evenly through height of grid
    (state.lineQuantity + 2).times do
      state.gridY << curr_y # adds curr_y to gridY collection
      curr_y += deltaY # increments curr_y to distance between horizontal lines
    end
  end

  # Determines coordinate positions of patterned tiles (on the left side of the grid)
  def determineTileCords
    state.tempCounter ||= 1 # initializes tempCounter to 1
    state.tileQuantity.times do # there are 6 different kinds of tiles
      state.tileCords += [[state.tempX, state.tempY, state.tempCounter]] # adds tile definition to collection
      state.tempX += 75 # increments tempX to put horizontal space between the patterned tiles
      state.tempCounter += 1 # increments tempCounter
      if state.tempX > 200 # if tempX exceeds 200 pixels
        state.tempX = 50 # a new row of patterned tiles begins
        state.tempY -= 75 # the new row is 75 pixels lower than the previous row
      end
    end
  end

  # Outputs objects (grid, tiles, etc) onto the screen
  def render
    outputs.sprites << state.tileCords.map do # outputs tileCords collection using images in sprites folder
      |x, y, order|
      [x, y, state.tileSize, state.tileSize, 'sprites/image' + order.to_s + ".png"]
    end
    outputs.solids << [0, 0, 1280, 720, 255, 255, 255] # outputs white background
    add_grid # outputs grid
    print_title # outputs title and current tile pattern
  end

  # Creates a grid by outputting vertical and horizontal grid lines onto the screen.
  # Outputs sprites for the filled_squares collection onto the screen.
  def add_grid

    # Outputs the grid's border.
    outputs.borders << state.grid_border
    temp = 0

    # Before looking at the code that outputs the vertical and horizontal lines in the
    # grid, take note of the fact that:
    # grid_border[1] refers to the border's bottom line (running horizontally),
    # grid_border[2] refers to the border's top line (running (horizontally),
    # grid_border[0] refers to the border's left line (running vertically),
    # and grid_border[3] refers to the border's right line (running vertically).

    #           [2]
    #       ----------
    #       |        |
    # [0]   |        | [3]
    #       |        |
    #       ----------
    #           [1]

    # Calculates the positions and outputs the x grid lines in the color gray.
    state.gridX.map do # perform an action on all elements of the gridX collection
      |x|
      temp += 1 # increment temp

      # if x's value is greater than (or equal to) the x value of the border's left side
      # and less than (or equal to) the x value of the border's right side
      if x >= state.centerX - (state.grid_border[2] / 2) && x <= state.centerX + (state.grid_border[2] / 2)
        delta = state.centerX - 640
        # vertical lines have the same starting and ending x positions
        # starting y and ending y positions lead from the bottom of the border to the top of the border
        outputs.lines << [x - delta, state.grid_border[1], x - delta, state.grid_border[1] + state.grid_border[2], 150, 150, 150] # sets definition of vertical line and outputs it
      end
    end
    temp = 0

    # Calculates the positions and outputs the y grid lines in the color gray.
    state.gridY.map do # perform an action on all elements of the gridY collection
      |y|
      temp += 1 # increment temp

      # if y's value is greater than (or equal to) the y value of the border's bottom side
      # and less than (or equal to) the y value of the border's top side
      if y >= state.centerY - (state.grid_border[3] / 2) && y <= state.centerY + (state.grid_border[3] / 2)
        delta = state.centerY - 393
        # horizontal lines have the same starting and ending y positions
        # starting x and ending x positions lead from the left side of the border to the right side of the border
        outputs.lines << [state.grid_border[0], y - delta, state.grid_border[0] + state.grid_border[3], y - delta, 150, 150, 150] # sets definition of horizontal line and outputs it
      end
    end

    # Sets values and outputs sprites for the filled_squares collection.
    state.filled_squares.map do # perform an action on every element of the filled_squares collection
      |x, y, w, h, sprite|
        # if x's value is greater than (or equal to) the x value of 17 pixels to the left of the border's left side
        # and less than (or equal to) the x value of the border's right side
        # and y's value is greater than (or equal to) the y value of the border's bottom side
        # and less than (or equal to) the y value of 25 pixels above the border's top side
        # NOTE: The allowance of 17 pixels and 25 pixels is due to the fact that a grid box may be slightly cut off or
        # not entirely visible in the grid's view (until it is moved using "W", "A", "S", "D")
        if x >= state.centerX - (state.grid_border[2] / 2) - 17 && x <= state.centerX + (state.grid_border[2] / 2) &&
           y >= state.centerY - (state.grid_border[3] / 2) && y <= state.centerY + (state.grid_border[3] / 2) + 25
          # calculations done to place sprites in grid spaces that are meant to filled in
          # mess around with the x and y values and see how the sprite placement changes
          outputs.sprites << [x - state.centerX + 630, y - state.centerY + 360, w, h, sprite]
        end
      end

      # outputs a white solid along the left side of the grid (change the color and you'll be able to see it against the white background)
      # state.increment subtracted in x parameter because solid's position is denoted by bottom left corner
      # state.increment subtracted in y parameter to avoid covering the title label
      outputs.primitives << [state.grid_border[0] - state.increment,
                             state.grid_border[1] - state.increment, state.increment, state.grid_border[3] + (state.increment * 2),
                             255, 255, 255].solid

      # outputs a white solid along the right side of the grid
      # state.increment subtracted from y parameter to avoid covering title label
      outputs.primitives << [state.grid_border[0] + state.grid_border[2],
                             state.grid_border[1] - state.increment, state.increment, state.grid_border[3] + (state.increment * 2),
                             255, 255, 255].solid

      # outputs a white solid along the bottom of the grid
      # state.increment subtracted from y parameter to avoid covering last row of grid boxes
      outputs.primitives << [state.grid_border[0] - state.increment, state.grid_border[1] - state.increment,
                             state.grid_border[2] + (2 * state.increment), state.increment, 255, 255, 255].solid

      # outputs a white solid along the top of the grid
      outputs.primitives << [state.grid_border[0] - state.increment, state.grid_border[1] + state.grid_border[3],
                             state.grid_border[2] + (2 * state.increment), state.increment, 255, 255, 255].solid

  end

  # Outputs title and current tile pattern
  def print_title
    outputs.labels << [640, 700, 'Mouse to Place Tile, WASD to Move Around', 7, 1] # title label
    outputs.lines << horizontal_separator(660, 0, 1280) # outputs horizontal separator
    outputs.labels << [1050, 500, 'Current:', 3, 1] # outputs Current label
    outputs.sprites << [1110, 474, state.tileSize / 2, state.tileSize / 2, 'sprites/image' + state.tileSelected.to_s + ".png"] # outputs sprite of current tile pattern using images in sprites folder; output is half the size of a tile
  end

  # Sets the starting position, ending position, and color for the horizontal separator.
  def horizontal_separator y, x, x2
    [x, y, x2, y, 150, 150, 150] # definition of separator; horizontal line means same starting/ending y
  end

  # Checks if the mouse is being clicked or dragged
  def check_click
    if inputs.keyboard.key_down.r # if the "r" key is pressed down
      $dragon.reset
    end

    if inputs.mouse.down #is mouse up or down?
      state.mouse_held = true
      if inputs.mouse.position.x < state.grid_border[0] # if mouse's x position is inside the grid's borders
        state.tileCords.map do # perform action on all elements of tileCords collection
          |x, y, order|
          # if mouse's x position is greater than (or equal to) the starting x position of a tile
          # and the mouse's x position is also less than (or equal to) the ending x position of that tile,
          # and the mouse's y position is greater than (or equal to) the starting y position of that tile,
          # and the mouse's y position is also less than (or equal to) the ending y position of that tile,
          # (BASICALLY, IF THE MOUSE'S POSITION IS WITHIN THE STARTING AND ENDING POSITIONS OF A TILE)
          if inputs.mouse.position.x >= x && inputs.mouse.position.x <= x + state.tileSize &&
             inputs.mouse.position.y >= y && inputs.mouse.position.y <= y + state.tileSize
            state.tileSelected = order # that tile is selected
          end
        end
      end
    elsif inputs.mouse.up # otherwise, if the mouse is in the "up" state
      state.mouse_held = false # mouse is not held down or dragged
      state.mouse_dragging = false
    end

    if state.mouse_held &&    # mouse needs to be down
       !inputs.mouse.click &&     # must not be first click
       ((inputs.mouse.previous_click.point.x - inputs.mouse.position.x).abs > 15 ||
        (inputs.mouse.previous_click.point.y - inputs.mouse.position.y).abs > 15) # Need to move 15 pixels before "drag"
      state.mouse_dragging = true
    end

    # if mouse is clicked inside grid's border, search_lines method is called with click input type
    if ((inputs.mouse.click) && (inputs.mouse.click.point.inside_rect? state.grid_border))
      search_lines(inputs.mouse.click.point, :click)

    # if mouse is dragged inside grid's border, search_lines method is called with drag input type
    elsif ((state.mouse_dragging) && (inputs.mouse.position.inside_rect? state.grid_border))
      search_lines(inputs.mouse.position, :drag)
    end

    # Changes grid's position on screen by moving it up, down, left, or right.

    # centerX is incremented by speed if the "d" key is pressed and if that sum is less than
    # the original left side of the center plus half the grid, minus half the top border of grid.
    # MOVES GRID RIGHT (increasing x)
    state.centerX += state.speed if inputs.keyboard.key_held.d &&
                                    (state.centerX + state.speed) < state.originalCenter[0] + (state.gridSize / 2) - (state.grid_border[2] / 2)
    # centerX is decremented by speed if the "a" key is pressed and if that difference is greater than
    # the original left side of the center minus half the grid, plus half the top border of grid.
    # MOVES GRID LEFT (decreasing x)
    state.centerX -= state.speed if inputs.keyboard.key_held.a &&
                                    (state.centerX - state.speed) > state.originalCenter[0] - (state.gridSize / 2) + (state.grid_border[2] / 2)
    # centerY is incremented by speed if the "w" key is pressed and if that sum is less than
    # the original bottom of the center plus half the grid, minus half the right border of grid.
    # MOVES GRID UP (increasing y)
    state.centerY += state.speed if inputs.keyboard.key_held.w &&
                                    (state.centerY + state.speed) < state.originalCenter[1] + (state.gridSize / 2) - (state.grid_border[3] / 2)
    # centerY is decremented by speed if the "s" key is pressed and if the difference is greater than
    # the original bottom of the center minus half the grid, plus half the right border of grid.
    # MOVES GRID DOWN (decreasing y)
    state.centerY -= state.speed if inputs.keyboard.key_held.s &&
                                    (state.centerY - state.speed) > state.originalCenter[1] - (state.gridSize / 2) + (state.grid_border[3] / 2)
  end

  # Performs calculations on the gridX and gridY collections, and sets values.
  # Sets the definition of a grid box, including the image that it is filled with.
  def search_lines (point, input_type)
    point.x += state.centerX - 630 # increments x and y
    point.y += state.centerY - 360
    findX = 0
    findY = 0
    increment = state.gridSize / state.lineQuantity # divides grid by number of separators

    state.gridX.map do # perform an action on every element of collection
      |x|
      # findX increments x by 10 if point.x is less than that sum and findX is currently 0
      findX = x + 10 if point.x < (x + 10) && findX == 0
    end

    state.gridY.map do
      |y|
      # findY is set to y if point.y is less than that value and findY is currently 0
      findY = y if point.y < (y) && findY == 0
    end
    # position of a box is denoted by bottom left corner, which is why the increment is being subtracted
    grid_box = [findX - (increment.ceil), findY - (increment.ceil), increment.ceil, increment.ceil,
                "sprites/image" + state.tileSelected.to_s + ".png"] # sets sprite definition

    if input_type == :click # if user clicks their mouse
      if state.filled_squares.include? grid_box # if grid box is already filled in
        state.filled_squares.delete grid_box # box is cleared and removed from filled_squares
      else
        state.filled_squares << grid_box # otherwise, box is filled in and added to filled_squares
      end
    elsif input_type == :drag # if user drags mouse
      unless state.filled_squares.include? grid_box # unless grid box dragged over is already filled in
        state.filled_squares << grid_box # box is filled in and added to filled_squares
      end
    end
  end

  # Creates a "Clear" button using labels and borders.
  def draw_buttons
    x, y, w, h = 390, 50, 240, 50
    state.clear_button        ||= state.new_entity(:button_with_fade)

    # x and y positions are set to display "Clear" label in center of the button
    # Try changing first two parameters to simply x, y and see what happens to the text placement
    state.clear_button.label  ||= [x + w.half, y + h.half + 10, "Clear", 0, 1]
    state.clear_button.border ||= [x, y, w, h] # definition of button's border

    # If the mouse is clicked inside the borders of the clear button
    if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.clear_button.border)
      state.clear_button.clicked_at = inputs.mouse.click.created_at # value is frame of mouse click
      state.filled_squares.clear # filled squares collection is emptied (squares are cleared)
      inputs.mouse.previous_click = nil # no previous click
    end

    outputs.labels << state.clear_button.label # outputs clear button
    outputs.borders << state.clear_button.border

    # When the clear button is clicked, the color of the button changes
    # and the transparency changes, as well. If you change the time from
    # 0.25.seconds to 1.25.seconds or more, the change will last longer.
    if state.clear_button.clicked_at
      outputs.solids << [x, y, w, h, 0, 180, 80, 255 * state.clear_button.clicked_at.ease(0.25.seconds, :flip)]
    end
  end
end

$tile_editor = TileEditor.new

def tick args
  $tile_editor.inputs = args.inputs
  $tile_editor.grid = args.grid
  $tile_editor.args = args
  $tile_editor.outputs = args.outputs
  $tile_editor.state = args.state
  $tile_editor.tick
  tick_instructions args, "Roll your own tile editor. CLICK to select a sprite. CLICK in grid to place sprite. WASD to move around."
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Genre Dungeon Crawl link

    Classics Jam - main.rb link

    # ./samples/99_genre_dungeon_crawl/classics_jam/app/main.rb
class Game
  attr_gtk

  def tick
    defaults
    render
    input
    calc
  end

  def defaults
    player.x              ||= 640
    player.y              ||= 360
    player.w              ||= 16
    player.h              ||= 16
    player.attacked_at    ||= -1
    player.angle          ||= 0
    player.future_player  ||= future_player_position 0, 0
    player.projectiles    ||= []
    player.damage         ||= 0
    state.level           ||= create_level level_one_template
  end

  def render
    outputs.sprites << level.walls.map do |w|
      w.merge(path: 'sprites/square/gray.png')
    end

    outputs.sprites << level.spawn_locations.map do |s|
      s.merge(path: 'sprites/square/blue.png')
    end

    outputs.sprites << player.projectiles.map do |p|
      p.merge(path: 'sprites/square/blue.png')
    end

    outputs.sprites << level.enemies.map do |e|
      e.merge(path: 'sprites/square/red.png')
    end

    outputs.sprites << player.merge(path: 'sprites/circle/green.png', angle: player.angle)

    outputs.labels << { x: 30, y: 30.from_top, text: "damage: #{player.damage || 0}" }
  end

  def input
    player.angle = inputs.directional_angle || player.angle
    if inputs.controller_one.key_down.a || inputs.keyboard.key_down.space
      player.attacked_at = state.tick_count
    end
  end

  def calc
    calc_player
    calc_projectiles
    calc_enemies
    calc_spawn_locations
  end

  def calc_player
    if player.attacked_at == state.tick_count
      player.projectiles << { at: state.tick_count,
                              x: player.x,
                              y: player.y,
                              angle: player.angle,
                              w: 4,
                              h: 4 }.center_inside_rect(player)
    end

    if player.attacked_at.elapsed_time > 5
      future_player = future_player_position inputs.left_right * 2, inputs.up_down * 2
      future_player_collision = future_collision player, future_player, level.walls
      player.x = future_player_collision.x if !future_player_collision.dx_collision
      player.y = future_player_collision.y if !future_player_collision.dy_collision
    end
  end

  def calc_projectile_collisions entities
    entities.each do |e|
      e.damage ||= 0
      player.projectiles.each do |p|
        if !p.collided && (p.intersect_rect? e)
          p.collided = true
          e.damage  += 1
        end
      end
    end
  end

  def calc_projectiles
    player.projectiles.map! do |p|
      dx, dy = p.angle.vector 10
      p.merge(x: p.x + dx, y: p.y + dy)
    end

    calc_projectile_collisions level.walls + level.enemies + level.spawn_locations
    player.projectiles.reject! { |p| p.at.elapsed_time > 10000 }
    player.projectiles.reject! { |p| p.collided }
    level.enemies.reject! { |e| e.damage > e.hp }
    level.spawn_locations.reject! { |s| s.damage > s.hp }
  end

  def calc_enemies
    level.enemies.map! do |e|
      dx =  0
      dx =  1 if e.x < player.x
      dx = -1 if e.x > player.x
      dy =  0
      dy =  1 if e.y < player.y
      dy = -1 if e.y > player.y
      future_e           = future_entity_position dx, dy, e
      future_e_collision = future_collision e, future_e, level.enemies + level.walls
      e.next_x = e.x
      e.next_y = e.y
      e.next_x = future_e_collision.x if !future_e_collision.dx_collision
      e.next_y = future_e_collision.y if !future_e_collision.dy_collision
      e
    end

    level.enemies.map! do |e|
      e.x = e.next_x
      e.y = e.next_y
      e
    end

    level.enemies.each do |e|
      player.damage += 1 if e.intersect_rect? player
    end
  end

  def calc_spawn_locations
    level.spawn_locations.map! do |s|
      s.merge(countdown: s.countdown - 1)
    end
    level.spawn_locations
         .find_all { |s| s.countdown.neg? }
         .each do |s|
      s.countdown = s.rate
      s.merge(countdown: s.rate)
      new_enemy = create_enemy s
      if !(level.enemies.find { |e| e.intersect_rect? new_enemy })
        level.enemies << new_enemy
      end
    end
  end

  def create_enemy spawn_location
    to_cell(spawn_location.ordinal_x, spawn_location.ordinal_y).merge hp: 2
  end

  def create_level level_template
    {
      walls:           level_template.walls.map { |w| to_cell(w.ordinal_x, w.ordinal_y).merge(w) },
      enemies:         [],
      spawn_locations: level_template.spawn_locations.map { |s| to_cell(s.ordinal_x, s.ordinal_y).merge(s) }
    }
  end

  def level_one_template
    {
      walls:           [{ ordinal_x: 25, ordinal_y: 20},
                        { ordinal_x: 25, ordinal_y: 21},
                        { ordinal_x: 25, ordinal_y: 22},
                        { ordinal_x: 25, ordinal_y: 23}],
      spawn_locations: [{ ordinal_x: 10, ordinal_y: 10, rate: 120, countdown: 0, hp: 5 }]
    }
  end

  def player
    state.player ||= {}
  end

  def level
    state.level  ||= {}
  end

  def future_collision entity, future_entity, others
    dx_collision = others.find { |o| o != entity && (o.intersect_rect? future_entity.dx) }
    dy_collision = others.find { |o| o != entity && (o.intersect_rect? future_entity.dy) }

    {
      dx_collision: dx_collision,
      x: future_entity.dx.x,
      dy_collision: dy_collision,
      y: future_entity.dy.y
    }
  end

  def future_entity_position dx, dy, entity
    {
      dx:   entity.merge(x: entity.x + dx),
      dy:   entity.merge(y: entity.y + dy),
      both: entity.merge(x: entity.x + dx, y: entity.y + dy)
    }
  end

  def future_player_position  dx, dy
    future_entity_position dx, dy, player
  end

  def to_cell ordinal_x, ordinal_y
    { x: ordinal_x * 16, y: ordinal_y * 16, w: 16, h: 16 }
  end
end

def tick args
  $game ||= Game.new
  $game.args = args
  $game.tick
end

$gtk.reset
$game = nil

    Genre Fighting link

    Special Move Inputs - main.rb link

    # ./samples/99_genre_fighting/01_special_move_inputs/app/main.rb
def tick args
  #tick_instructions args, "Use LEFT and RIGHT arrow keys to move and SPACE to jump."
  defaults args
  render args
  input args
  calc args
end

# sets default values and creates empty collections
# initialization only happens in the first frame
def defaults args
  fiddle args

  args.state.tick_count = args.state.tick_count
  args.state.bridge_top = 128
  args.state.player.x  ||= 0                        # initializes player's properties
  args.state.player.y  ||= args.state.bridge_top
  args.state.player.w  ||= 64
  args.state.player.h  ||= 64
  args.state.player.dy ||= 0
  args.state.player.dx ||= 0
  args.state.player.r  ||= 0
  args.state.game_over_at ||= 0
  args.state.animation_time ||=0

  args.state.timeleft ||=0
  args.state.timeright ||=0
  args.state.lastpush ||=0

  args.state.inputlist ||=  ["j","k","l"]
end

# sets enemy, player, hammer values
def fiddle args
  args.state.gravity                     = -0.5
  args.state.player_jump_power           = 10      # sets player values
  args.state.player_jump_power_duration  = 5
  args.state.player_max_run_speed        = 20
  args.state.player_speed_slowdown_rate  = 0.9
  args.state.player_acceleration         = 0.9
end

# outputs objects onto the screen
def render args
  if (args.state.player.dx < 0.01) && (args.state.player.dx > -0.01)
    args.state.player.dx = 0
  end

  #move list
  (args.layout.rect_group row: 0, col_from_right: 8, drow: 0.3,
                          merge: { vertical_alignment_enum: 0, size_enum: -2 },
                          group: [
                            { text: "move:             WASD" },
                            { text: "jump:             Space" },
                            { text: "attack forwards:  J (while on ground" },
                            { text: "attack upwards:   K (while on groud)" },
                            { text: "attack backwards: J (while on ground and holding A)" },
                            { text: "attack downwards: K (while in air)" },
                            { text: "dash attack:      J, K in quick succession." },
                            { text: "shield: hold      J, K at the same time." },
                            { text: "dash backwards:   A, A in quick succession." },
                          ]).into args.outputs.labels

  # registered moves
  args.outputs.labels << { x: 0.to_layout_col,
                           y: 0.to_layout_row,
                           text: "input history",
                           size_enum: -2,
                           vertical_alignment_enum: 0 }

  (args.state.inputlist.take(5)).map do |s|
    { text: s, size_enum: -2, vertical_alignment_enum: 0 }
  end.yield_self do |group|
    (args.layout.rect_group row: 0.3, col: 0, drow: 0.3, group: group).into args.outputs.labels
  end


  #sprites
  player = [args.state.player.x, args.state.player.y,
            args.state.player.w, args.state.player.h,
            "sprites/square/white.png",
            args.state.player.r]

  playershield = [args.state.player.x - 20, args.state.player.y - 10,
                  args.state.player.w + 20, args.state.player.h + 20,
                  "sprites/square/blue.png",
                  args.state.player.r,
                  0]

  playerjab = [args.state.player.x + 32, args.state.player.y,
               args.state.player.w, args.state.player.h,
               "sprites/isometric/indigo.png",
               args.state.player.r,
               0]

  playerupper = [args.state.player.x, args.state.player.y + 32,
                 args.state.player.w, args.state.player.h,
                 "sprites/isometric/indigo.png",
                 args.state.player.r+90,
                 0]

  if ((args.state.tick_count - args.state.lastpush) <= 15)
    if (args.state.inputlist[0] == "<<")
      player = [args.state.player.x, args.state.player.y,
                args.state.player.w, args.state.player.h,
                "sprites/square/yellow.png", args.state.player.r]
    end

    if (args.state.inputlist[0] == "shield")
      player = [args.state.player.x, args.state.player.y,
                args.state.player.w, args.state.player.h,
                "sprites/square/indigo.png", args.state.player.r]

      playershield = [args.state.player.x - 10, args.state.player.y - 10,
                      args.state.player.w + 20, args.state.player.h + 20,
                      "sprites/square/blue.png", args.state.player.r, 50]
    end

    if (args.state.inputlist[0] == "back-attack")
      playerjab = [args.state.player.x - 20, args.state.player.y,
                   args.state.player.w - 10, args.state.player.h,
                   "sprites/isometric/indigo.png", args.state.player.r, 255]
    end

    if (args.state.inputlist[0] == "forward-attack")
      playerjab = [args.state.player.x + 32, args.state.player.y,
                   args.state.player.w, args.state.player.h,
                   "sprites/isometric/indigo.png", args.state.player.r, 255]
    end

    if (args.state.inputlist[0] == "up-attack")
      playerupper = [args.state.player.x, args.state.player.y + 32,
                     args.state.player.w, args.state.player.h,
                     "sprites/isometric/indigo.png", args.state.player.r + 90, 255]
    end

    if (args.state.inputlist[0] == "dair")
      playerupper = [args.state.player.x, args.state.player.y - 32,
                     args.state.player.w, args.state.player.h,
                     "sprites/isometric/indigo.png", args.state.player.r + 90, 255]
    end

    if (args.state.inputlist[0] == "dash-attack")
      playerupper = [args.state.player.x, args.state.player.y + 32,
                     args.state.player.w, args.state.player.h,
                     "sprites/isometric/violet.png", args.state.player.r + 90, 255]

      playerjab = [args.state.player.x + 32, args.state.player.y,
                   args.state.player.w, args.state.player.h,
                   "sprites/isometric/violet.png", args.state.player.r, 255]
    end
  end

  args.outputs.sprites << playerjab
  args.outputs.sprites << playerupper
  args.outputs.sprites << player
  args.outputs.sprites << playershield

  args.outputs.solids << 20.map_with_index do |i| # uses 20 squares to form bridge
    [i * 64, args.state.bridge_top - 64, 64, 64]
  end
end

# Performs calculations to move objects on the screen
def calc args
  # Since velocity is the change in position, the change in x increases by dx. Same with y and dy.
  args.state.player.x  += args.state.player.dx
  args.state.player.y  += args.state.player.dy

  # Since acceleration is the change in velocity, the change in y (dy) increases every frame
  args.state.player.dy += args.state.gravity

  # player's y position is either current y position or y position of top of
  # bridge, whichever has a greater value
  # ensures that the player never goes below the bridge
  args.state.player.y  = args.state.player.y.greater(args.state.bridge_top)

  # player's x position is either the current x position or 0, whichever has a greater value
  # ensures that the player doesn't go too far left (out of the screen's scope)
  args.state.player.x  = args.state.player.x.greater(0)

  # player is not falling if it is located on the top of the bridge
  args.state.player.falling = false if args.state.player.y == args.state.bridge_top
  #args.state.player.rect = [args.state.player.x, args.state.player.y, args.state.player.h, args.state.player.w] # sets definition for player
end

# Resets the player by changing its properties back to the values they had at initialization
def reset_player args
  args.state.player.x = 0
  args.state.player.y = args.state.bridge_top
  args.state.player.dy = 0
  args.state.player.dx = 0
  args.state.enemy.hammers.clear # empties hammer collection
  args.state.enemy.hammer_queue.clear # empties hammer_queue
  args.state.game_over_at = args.state.tick_count # game_over_at set to current frame (or passage of time)
end

# Processes input from the user to move the player
def input args
  if args.state.inputlist.length > 5
    args.state.inputlist.pop
  end

  should_process_special_move = (args.inputs.keyboard.key_down.j)           ||
                                (args.inputs.keyboard.key_down.k)           ||
                                (args.inputs.keyboard.key_down.a)           ||
                                (args.inputs.keyboard.key_down.d)           ||
                                (args.inputs.controller_one.key_down.y)     ||
                                (args.inputs.controller_one.key_down.x)     ||
                                (args.inputs.controller_one.key_down.left)  ||
                                (args.inputs.controller_one.key_down.right)

  if (should_process_special_move)
    if (args.inputs.keyboard.key_down.j && args.inputs.keyboard.key_down.k) ||
       (args.inputs.controller_one.key_down.x && args.inputs.controller_one.key_down.y)
      args.state.inputlist.unshift("shield")
    elsif (args.inputs.keyboard.key_down.k || args.inputs.controller_one.key_down.y) &&
          (args.state.inputlist[0] == "forward-attack") && ((args.state.tick_count - args.state.lastpush) <= 15)
      args.state.inputlist.unshift("dash-attack")
      args.state.player.dx = 20
    elsif (args.inputs.keyboard.key_down.j && args.inputs.keyboard.a) ||
          (args.inputs.controller_one.key_down.x && args.inputs.controller_one.key_down.left)
      args.state.inputlist.unshift("back-attack")
    elsif ( args.inputs.controller_one.key_down.x || args.inputs.keyboard.key_down.j)
      args.state.inputlist.unshift("forward-attack")
    elsif (args.inputs.keyboard.key_down.k || args.inputs.controller_one.key_down.y) &&
          (args.state.player.y > 128)
      args.state.inputlist.unshift("dair")
    elsif (args.inputs.keyboard.key_down.k || args.inputs.controller_one.key_down.y)
      args.state.inputlist.unshift("up-attack")
    elsif (args.inputs.controller_one.key_down.left || args.inputs.keyboard.key_down.a) &&
          (args.state.inputlist[0] == "<") &&
          ((args.state.tick_count - args.state.lastpush) <= 10)
      args.state.inputlist.unshift("<<")
      args.state.player.dx = -15
    elsif (args.inputs.controller_one.key_down.left || args.inputs.keyboard.key_down.a)
      args.state.inputlist.unshift("<")
      args.state.timeleft = args.state.tick_count
    elsif (args.inputs.controller_one.key_down.right || args.inputs.keyboard.key_down.d)
      args.state.inputlist.unshift(">")
    end

    args.state.lastpush = args.state.tick_count
  end

  if args.inputs.keyboard.space || args.inputs.controller_one.r2   # if the user presses the space bar
    args.state.player.jumped_at ||= args.state.tick_count # jumped_at is set to current frame

    # if the time that has passed since the jump is less than the player's jump duration and
    # the player is not falling
    if args.state.player.jumped_at.elapsed_time < args.state.player_jump_power_duration && !args.state.player.falling
      args.state.player.dy = args.state.player_jump_power # change in y is set to power of player's jump
    end
  end

  # if the space bar is in the "up" state (or not being pressed down)
  if args.inputs.keyboard.key_up.space || args.inputs.controller_one.key_up.r2
    args.state.player.jumped_at = nil # jumped_at is empty
    args.state.player.falling = true # the player is falling
  end

  if args.inputs.left # if left key is pressed
    if args.state.player.dx < -5
      args.state.player.dx = args.state.player.dx
    else
      args.state.player.dx = -5
    end

  elsif args.inputs.right # if right key is pressed
    if args.state.player.dx > 5
      args.state.player.dx = args.state.player.dx
    else
      args.state.player.dx = 5
    end
  else
    args.state.player.dx *= args.state.player_speed_slowdown_rate # dx is scaled down
  end

  if ((args.state.player.dx).abs > 5) #&& ((args.state.tick_count - args.state.lastpush) <= 10)
    args.state.player.dx *= 0.95
  end
end

def tick_instructions args, text, y = 715
  return if args.state.key_event_occurred
  if args.inputs.mouse.click ||
     args.inputs.keyboard.directional_vector ||
     args.inputs.keyboard.key_down.enter ||
     args.inputs.keyboard.key_down.space ||
     args.inputs.keyboard.key_down.escape
    args.state.key_event_occurred = true
  end

  args.outputs.debug << [0, y - 50, 1280, 60].solid
  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end

    Genre Lowrez link

    Nokia 3310 - main.rb link

    # ./samples/99_genre_lowrez/nokia_3310/app/main.rb
require 'app/nokia.rb'

def tick args
  # =======================================================================
  # ==== HELLO WORLD ======================================================
  # =======================================================================
  # Steps to get started:
  # 1. ~def tick args~ is the entry point for your game.
  # 2. There are quite a few code samples below, remove the "##"
  #    before each line and save the file to see the changes.
  # 3. 0,  0 is in bottom left and 83, 47 is in top right corner.
  # 4. Be sure to come to the discord channel if you need
  #    more help: [[http://discord.dragonruby.org]].

  # Commenting and uncommenting code:
  # - Add a "#" infront of lines to comment out code
  # - Remove the "#" infront of lines to comment out code

  # Invoke the hello_world subroutine/method
  hello_world args # <---- add a "#" to the beginning of the line to stop running this subroutine/method.

  # =======================================================================
  # ==== HOW TO RENDER A LABEL ============================================
  # =======================================================================

  # Uncomment the line below to invoke the how_to_render_a_label subroutine/method.
  # Note: The method is defined in this file with the signature ~def how_to_render_a_label args~
  #       Scroll down to the method to see the details.

  # Remove the "#" at the beginning of the line below
  # how_to_render_a_label args # <---- remove the "#" at the beginning of this line to run the method


  # =======================================================================
  # ==== HOW TO RENDER A FILLED SQUARE (SOLID) ============================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_render_solids args


  # =======================================================================
  # ==== HOW TO RENDER AN UNFILLED SQUARE (BORDER) ========================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_render_borders args


  # =======================================================================
  # ==== HOW TO RENDER A LINE =============================================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_render_lines args


  # =======================================================================
  # == HOW TO RENDER A SPRITE =============================================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_render_sprites args


  # =======================================================================
  # ==== HOW TO MOVE A SPRITE BASED OFF OF USER INPUT =====================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_move_a_sprite args


  # =======================================================================
  # ==== HOW TO ANIMATE A SPRITE (SEPERATE PNGS) ==========================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_animate_a_sprite args


  # =======================================================================
  # ==== HOW TO ANIMATE A SPRITE (SPRITE SHEET) ===========================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_animate_a_sprite_sheet args


  # =======================================================================
  # ==== HOW TO DETERMINE COLLISION =============================================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_determine_collision args


  # =======================================================================
  # ==== HOW TO CREATE BUTTONS ==================================================
  # =======================================================================
  # Remove the "#" at the beginning of the line below
  # how_to_create_buttons args

  # ==== The line below renders a debug grid, mouse information, and current tick
  # render_debug args
end

# =======================================================================
# ==== HELLO WORLD ======================================================
# =======================================================================
def hello_world args
  args.nokia.solids  << { x: 0, y: 64, w: 10, h: 10, r: 255 }

  args.nokia.labels  << {
    x: 42,
    y: 46,
    text: "nokia 3310 jam 3",
    size_enum: NOKIA_FONT_SM,
    alignment_enum: 1,
    r: 0,
    g: 0,
    b: 0,
    a: 255,
    font: NOKIA_FONT_PATH
  }

  args.nokia.sprites << {
    x: 42 - 10,
    y: 26 - 10,
    w: 20,
    h: 20,
    path: 'sprites/monochrome-ship.png',
    a: 255,
    angle: args.state.tick_count % 360
  }
end

# =======================================================================
# ==== HOW TO RENDER A LABEL ============================================
# =======================================================================
def how_to_render_a_label args
  # NOTE: Text is aligned from the TOP LEFT corner

  # Render an EXTRA LARGE/XL label (remove the "#" in front of each line below)
  args.nokia.labels << { x: 0, y: 46, text: "Hello World",
                         size_enum: NOKIA_FONT_XL,
                         r: 0, g: 0, b: 0, a: 255,
                         font: NOKIA_FONT_PATH }

  # Render a LARGE/LG label (remove the "#" in front of each line below)
  args.nokia.labels << { x: 0, y: 29, text: "Hello World",
                          size_enum: NOKIA_FONT_LG,
                          r: 0, g: 0, b: 0, a: 255,
                          font: NOKIA_FONT_PATH }

  # Render a MEDIUM/MD label (remove the "#" in front of each line below)
  args.nokia.labels << { x: 0, y: 16, text: "Hello World",
                          size_enum: NOKIA_FONT_MD,
                          r: 0, g: 0, b: 0, a: 255,
                          font: NOKIA_FONT_PATH }

  # Render a SMALL/SM label (remove the "#" in front of each line below)
  args.nokia.labels << { x: 0, y: 7, text: "Hello World",
                          size_enum: NOKIA_FONT_SM,
                          r: 0, g: 0, b: 0, a: 255,
                          font: NOKIA_FONT_PATH }

  # You are provided args.nokia.default_label which returns a Hash that you
  # can ~merge~ properties with
  # Example 1
  args.nokia.labels << args.nokia
                            .default_label
                            .merge(text: "Default")

  # Example 2
  args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 31,
                                   text: "Default")
end

# =============================================================================
# ==== HOW TO RENDER FILLED SQUARES (SOLIDS) ==================================
# =============================================================================
def how_to_render_solids args
  # Render a square at 0, 0 with a width and height of 1
  args.nokia.solids << { x: 0, y: 0, w: 1, h: 1 }

  # Render a square at 1, 1 with a width and height of 2
  args.nokia.solids << { x: 1, y: 1, w: 2, h: 2 }

  # Render a square at 3, 3 with a width and height of 3
  args.nokia.solids << { x: 3, y: 3, w: 3, h: 3 }

  # Render a square at 6, 6 with a width and height of 4
  args.nokia.solids << { x: 6, y: 6, w: 4, h: 4 }
end

# =============================================================================
# ==== HOW TO RENDER UNFILLED SQUARES (BORDERS) ===============================
# =============================================================================
def how_to_render_borders args
  # Render a square at 0, 0 with a width and height of 3
  args.nokia.borders << { x: 0, y: 0, w: 3, h: 3, a: 255 }

  # Render a square at 3, 3 with a width and height of 3
  args.nokia.borders << { x: 3, y: 3, w: 4, h: 4, a: 255 }

  # Render a square at 5, 5 with a width and height of 4
  args.nokia.borders << { x: 7, y: 7, w: 5, h: 5, a: 255 }
end

# =============================================================================
# ==== HOW TO RENDER A LINE ===================================================
# =============================================================================
def how_to_render_lines args
  # Render a horizontal line at the bottom
  args.nokia.lines << { x: 0, y: 0, x2: 83, y2:  0 }

  # Render a vertical line at the left
  args.nokia.lines << { x: 0, y: 0, x2:  0, y2: 47 }

  # Render a diagonal line starting from the bottom left and going to the top right
  args.nokia.lines << { x: 0, y: 0, x2: 83, y2: 47 }
end

# =============================================================================
# == HOW TO RENDER A SPRITE ===================================================
# =============================================================================
def how_to_render_sprites args
  # Loop 10 times and create 10 sprites in 10 positions
  # Render a sprite at the bottom left with a width and height of 5 and a path of 'sprites/monochrome-ship.png'
  10.times do |i|
    args.nokia.sprites << {
      x: i * 8.4,
      y: i * 4.8,
      w: 5,
      h: 5,
      path: 'sprites/monochrome-ship.png'
    }
  end

  # Given an array of positions create sprites
  positions = [
    { x: 20, y: 32 },
    { x: 45, y: 15 },
    { x: 72, y: 23 },
  ]

  positions.each do |position|
    # use Ruby's ~Hash#merge~ function to create a sprite
    args.nokia.sprites << position.merge(path: 'sprites/monochrome-ship.png',
                                          w: 5,
                                          h: 5)
  end
end

# =============================================================================
# ==== HOW TO ANIMATE A SPRITE (SEPERATE PNGS) ==========================
# =============================================================================
def how_to_animate_a_sprite args
  # STEP 1: Define when you want the animation to start. The animation in this case will start in 3 seconds
  start_animation_on_tick = 180

  # STEP 2: Get the frame_index given the start tick.
  sprite_index = start_animation_on_tick.frame_index count: 7,     # how many sprites?
                                                     hold_for: 8,  # how long to hold each sprite?
                                                     repeat: true  # should it repeat?

  # STEP 3: frame_index will return nil if the frame hasn't arrived yet
  if sprite_index
    # if the sprite_index is populated, use it to determine the sprite path and render it
    sprite_path  = "sprites/explosion-#{sprite_index}.png"
    args.nokia.sprites << { x: 42 - 16,
                             y: 47 - 32,
                             w: 32,
                             h: 32,
                             path: sprite_path }
  else
    # if the sprite_index is nil, render a countdown instead
    countdown_in_seconds = ((start_animation_on_tick - args.state.tick_count) / 60).round(1)

    args.nokia.labels  << args.nokia
                               .default_label
                               .merge(x: 0,
                                      y: 18,
                                      text: "Count Down: #{countdown_in_seconds.to_sf}",
                                      alignment_enum: 0)
  end

  # render the current tick and the resolved sprite index
  args.nokia.labels  << args.nokia
                               .default_label
                               .merge(x: 0,
                                      y: 11,
                                      text: "Tick: #{args.state.tick_count}")
  args.nokia.labels  << args.nokia
                               .default_label
                               .merge(x: 0,
                                      y: 5,
                                      text: "sprite_index: #{sprite_index}")
end

# =============================================================================
# ==== HOW TO ANIMATE A SPRITE (SPRITE SHEET) =================================
# =============================================================================
def how_to_animate_a_sprite_sheet args
  # STEP 1: Define when you want the animation to start. The animation in this case will start in 3 seconds
  start_animation_on_tick = 180

  # STEP 2: Get the frame_index given the start tick.
  sprite_index = start_animation_on_tick.frame_index count: 7,     # how many sprites?
                                                     hold_for: 8,  # how long to hold each sprite?
                                                     repeat: true  # should it repeat?

  # STEP 3: frame_index will return nil if the frame hasn't arrived yet
  if sprite_index
    # if the sprite_index is populated, use it to determine the source rectangle and render it
    args.nokia.sprites << {
      x: 42 - 16,
      y: 47 - 32,
      w: 32,
      h: 32,
      path:  "sprites/explosion-sheet.png",
      source_x: 32 * sprite_index,
      source_y: 0,
      source_w: 32,
      source_h: 32
    }
  else
    # if the sprite_index is nil, render a countdown instead
    countdown_in_seconds = ((start_animation_on_tick - args.state.tick_count) / 60).round(1)

    args.nokia.labels  << args.nokia
                               .default_label
                               .merge(x: 0,
                                      y: 18,
                                      text: "Count Down: #{countdown_in_seconds.to_sf}",
                                      alignment_enum: 0)
  end

  # render the current tick and the resolved sprite index
  args.nokia.labels  << args.nokia
                               .default_label
                               .merge(x: 0,
                                      y: 11,
                                      text: "tick: #{args.state.tick_count}")
  args.nokia.labels  << args.nokia
                               .default_label
                               .merge(x: 0,
                                      y: 5,
                                      text: "sprite_index: #{sprite_index}")
end

# =============================================================================
# ==== HOW TO STORE STATE, ACCEPT INPUT, AND RENDER SPRITE BASED OFF OF STATE =
# =============================================================================
def how_to_move_a_sprite args
  args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 46, text: "Use Arrow Keys",
                                   alignment_enum: 1)

  args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 41, text: "Or WASD",
                                   alignment_enum: 1)

  args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 36, text: "Or Click",
                                   alignment_enum: 1)

  # set the initial values for x and y using ||= ("or equal operator")
  args.state.ship.x ||= 0
  args.state.ship.y ||= 0

  # if a mouse click occurs, update the ship's x and y to be the location of the click
  if args.nokia.mouse_click
    args.state.ship.x = args.nokia.mouse_click.x
    args.state.ship.y = args.nokia.mouse_click.y
  end

  # if a or left arrow is pressed/held, decrement the ships x position
  if args.nokia.keyboard.left
    args.state.ship.x -= 1
  end

  # if d or right arrow is pressed/held, increment the ships x position
  if args.nokia.keyboard.right
    args.state.ship.x += 1
  end

  # if s or down arrow is pressed/held, decrement the ships y position
  if args.nokia.keyboard.down
    args.state.ship.y -= 1
  end

  # if w or up arrow is pressed/held, increment the ships y position
  if args.nokia.keyboard.up
    args.state.ship.y += 1
  end

  # render the sprite to the screen using the position stored in args.state.ship
  args.nokia.sprites << {
    x: args.state.ship.x,
    y: args.state.ship.y,
    w: 5,
    h: 5,
    path: 'sprites/monochrome-ship.png',
    # parameters beyond this point are optional
    angle: 0, # Note: rotation angle is denoted in degrees NOT radians
    r: 255,
    g: 255,
    b: 255,
    a: 255
  }
end

# =======================================================================
# ==== HOW TO DETERMINE COLLISION =======================================
# =======================================================================
def how_to_determine_collision args
  # Render the instructions
  args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 46, text: "Click Anywhere",
                                   alignment_enum: 1)

  # if a mouse click occurs:
  # - set ship_one if it isn't set
  # - set ship_two if it isn't set
  # - otherwise reset ship one and ship two
  if args.nokia.mouse_click
    # is ship_one set?
    if !args.state.ship_one
      args.state.ship_one = { x: args.nokia.mouse_click.x - 5,
                              y: args.nokia.mouse_click.y - 5,
                              w: 10,
                              h: 10 }
    # is ship_one set?
    elsif !args.state.ship_two
      args.state.ship_two = { x: args.nokia.mouse_click.x - 5,
                              y: args.nokia.mouse_click.y - 5,
                              w: 10,
                              h: 10 }
    # should we reset?
    else
      args.state.ship_one = nil
      args.state.ship_two = nil
    end
  end

  # render ship one if it's set
  if args.state.ship_one
    # use Ruby's .merge method which is available on ~Hash~ to set the sprite and alpha
    # render ship one
    args.nokia.sprites << args.state.ship_one.merge(path: 'sprites/monochrome-ship.png')
  end

  if args.state.ship_two
    # use Ruby's .merge method which is available on ~Hash~ to set the sprite and alpha
    # render ship two
    args.nokia.sprites << args.state.ship_two.merge(path: 'sprites/monochrome-ship.png')
  end

  # if both ship one and ship two are set, then determine collision
  if args.state.ship_one && args.state.ship_two
    # collision is determined using the intersect_rect? method
    if args.state.ship_one.intersect_rect? args.state.ship_two
      # if collision occurred, render the words collision!
      args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 5,
                                   text: "Collision!",
                                   alignment_enum: 1)
    else
      # if collision occurred, render the words no collision.
      args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 5,
                                   text: "No Collision.",
                                   alignment_enum: 1)
    end
  else
    # if both ship one and ship two aren't set, then render --
      args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 6,
                                   text: "--",
                                   alignment_enum: 1)
  end
end

# =============================================================================
# ==== HOW TO CREATE BUTTONS ==================================================
# =============================================================================
def how_to_create_buttons args
  # Define a button style
  args.state.button_style = { w: 82, h: 10, }

  # Render instructions
  args.state.button_message ||= "Press a Button!"
  args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: 42,
                                   y: 82,
                                   text: args.state.button_message,
                                   alignment_enum: 1)


  # Creates button one using a border and a label
  args.state.button_one_border = args.state.button_style.merge( x: 1, y: 32)
  args.nokia.borders << args.state.button_one_border
  args.nokia.labels  << args.nokia
                             .default_label
                             .merge(x: args.state.button_one_border.x + 2,
                                    y: args.state.button_one_border.y + NOKIA_FONT_SM_HEIGHT + 2,
                                    text: "Button One")

  # Creates button two using a border and a label
  args.state.button_two_border = args.state.button_style.merge( x: 1, y: 20)

  args.nokia.borders << args.state.button_two_border
  args.nokia.labels << args.nokia
                            .default_label
                            .merge(x: args.state.button_two_border.x + 2,
                                   y: args.state.button_two_border.y + NOKIA_FONT_SM_HEIGHT + 2,
                                   text: "Button Two")

  # Initialize the state variable that tracks which button was clicked to "" (empty stringI
  args.state.last_button_clicked ||= "--"

  # If a click occurs, check to see if either button one, or button two was clicked
  # using the inside_rect? method of the mouse
  # set args.state.last_button_clicked accordingly
  if args.nokia.mouse_click
    if args.nokia.mouse_click.inside_rect? args.state.button_one_border
      args.state.last_button_clicked = "One Clicked!"
    elsif args.nokia.mouse_click.inside_rect? args.state.button_two_border
      args.state.last_button_clicked = "Two Clicked!"
    else
      args.state.last_button_clicked = "--"
    end
  end

  # Render the current value of args.state.last_button_clicked
  args.nokia.labels << args.nokia
                             .default_label
                             .merge(x: 42,
                                    y: 5,
                                    text: args.state.last_button_clicked,
                                    alignment_enum: 1)
end

def render_debug args
  if !args.state.grid_rendered
    (NOKIA_HEIGHT + 1).map_with_index do |i|
      args.outputs.static_debug << {
        x:  NOKIA_X_OFFSET,
        y:  NOKIA_Y_OFFSET + (i * NOKIA_ZOOM),
        x2: NOKIA_X_OFFSET + NOKIA_ZOOMED_WIDTH,
        y2: NOKIA_Y_OFFSET + (i * NOKIA_ZOOM),
        r: 128,
        g: 128,
        b: 128,
        a: 80
      }.line
    end

    (NOKIA_WIDTH + 1).map_with_index do |i|
      args.outputs.static_debug << {
        x:  NOKIA_X_OFFSET + (i * NOKIA_ZOOM),
        y:  NOKIA_Y_OFFSET,
        x2: NOKIA_X_OFFSET + (i * NOKIA_ZOOM),
        y2: NOKIA_Y_OFFSET + NOKIA_ZOOMED_HEIGHT,
        r: 128,
        g: 128,
        b: 128,
        a: 80
      }.line
    end
  end

  args.state.grid_rendered = true

  args.state.last_click ||= 0
  args.state.last_up    ||= 0
  args.state.last_click   = args.state.tick_count if args.nokia.mouse_down # you can also use args.nokia.click
  args.state.last_up      = args.state.tick_count if args.nokia.mouse_up
  args.state.label_style  = { size_enum: -1.5 }

  args.state.watch_list = [
    "args.state.tick_count is:      #{args.state.tick_count}",
    "args.nokia.mouse_position is:  #{args.nokia.mouse_position.x}, #{args.nokia.mouse_position.y}",
    "args.nokia.mouse_down tick:    #{args.state.last_click || "never"}",
    "args.nokia.mouse_up tick:      #{args.state.last_up || "false"}",
  ]

  args.outputs.debug << args.state
                            .watch_list
                            .map_with_index do |text, i|
    {
      x: 5,
      y: 720 - (i * 18),
      text: text,
      size_enum: -1.5,
      r: 255, g: 255, b: 255
    }.label!
  end

  args.outputs.debug << {
    x: 640,
    y:  25,
    text: "INFO: dev mode is currently enabled. Comment out the invocation of ~render_debug~ within the ~tick~ method to hide the debug layer.",
    size_enum: -0.5,
    alignment_enum: 1,
    r: 255, g: 255, b: 255
  }.label!
end

def snake_demo args

end

$gtk.reset

    Nokia 3310 - nokia.rb link

    # ./samples/99_genre_lowrez/nokia_3310/app/nokia.rb
# Emulation of a 64x64 canvas. Don't change this file unless you know what you're doing :-)
# Head over to main.rb and study the code there.

NOKIA_WIDTH           = 84
NOKIA_HEIGHT          = 48
NOKIA_ZOOM            = 12
NOKIA_ZOOMED_WIDTH    = NOKIA_WIDTH  * NOKIA_ZOOM
NOKIA_ZOOMED_HEIGHT   = NOKIA_HEIGHT * NOKIA_ZOOM
NOKIA_X_OFFSET        = (1280 - NOKIA_ZOOMED_WIDTH).half
NOKIA_Y_OFFSET        = ( 720 - NOKIA_ZOOMED_HEIGHT).half

NOKIA_FONT_XL         = -1
NOKIA_FONT_XL_HEIGHT  = 20

NOKIA_FONT_LG         = -3.5
NOKIA_FONT_LG_HEIGHT  = 15

NOKIA_FONT_MD         = -6
NOKIA_FONT_MD_HEIGHT  = 10

NOKIA_FONT_SM         = -8.5
NOKIA_FONT_SM_HEIGHT  = 5

NOKIA_FONT_PATH       = 'fonts/lowrez.ttf'


class NokiaOutputs
  attr_accessor :width, :height

  def initialize args
    @args = args
  end

  def outputs_nokia
    return @args.outputs if @args.state.tick_count <= 0
    return @args.outputs[:nokia].transient!
  end

  def solids
    outputs_nokia.solids
  end

  def borders
    outputs_nokia.borders
  end

  def sprites
    outputs_nokia.sprites
  end

  def labels
    outputs_nokia.labels
  end

  def default_label
    {
      x: 0,
      y: 63,
      text: "",
      size_enum: NOKIA_FONT_SM,
      alignment_enum: 0,
      r: 0,
      g: 0,
      b: 0,
      a: 255,
      font: NOKIA_FONT_PATH
    }
  end

  def lines
    outputs_nokia.lines
  end

  def primitives
    outputs_nokia.primitives
  end

  def click
    return nil unless @args.inputs.mouse.click
    mouse
  end

  def mouse_click
    click
  end

  def mouse_down
    @args.inputs.mouse.down
  end

  def mouse_up
    @args.inputs.mouse.up
  end

  def mouse
    [
      ((@args.inputs.mouse.x - NOKIA_X_OFFSET).idiv(NOKIA_ZOOM)),
      ((@args.inputs.mouse.y - NOKIA_Y_OFFSET).idiv(NOKIA_ZOOM))
    ]
  end

  def mouse_position
    mouse
  end

  def keyboard
    @args.inputs.keyboard
  end
end

class GTK::Args
  def init_nokia
    return if @nokia
    @nokia = NokiaOutputs.new self
  end

  def nokia
    @nokia
  end
end

module GTK
  class Runtime
    alias_method :__original_tick_core__, :tick_core unless Runtime.instance_methods.include?(:__original_tick_core__)

    def tick_core
      @args.init_nokia

      __original_tick_core__

      return if @args.state.tick_count <= 0

      @args.render_target(:nokia)
           .labels
           .each do |l|
        l.y  += 1
        if (l.a || 255) > 128
          l.r = 67
          l.g = 82
          l.b = 61
          l.a = 255
        else
          l.a = 0
        end
      end

      @args.render_target(:nokia)
           .sprites
           .each do |s|
        if (s.a || 255) > 128
          s.a = 255
        else
          s.a = 0
        end
      end

      @args.render_target(:nokia)
           .solids
           .each do |s|
        if (s.a || 255) > 128
          s.r = 67
          s.g = 82
          s.b = 61
          s.a = 255
        else
          s.a = 0
        end
      end

      @args.render_target(:nokia)
           .borders
           .each do |s|
        if (s.a || 255) > 128
          s.r = 67
          s.g = 82
          s.b = 61
          s.a = 255
        else
          s.a = 0
        end
      end

      @args.render_target(:nokia)
           .lines
           .each do |l|
        l.y  += 1
        l.y2 += 1
        l.y2 += 1 if l.y1 != l.y2
        l.x2 += 1 if l.x1 != l.x2

        if (l.a || 255) > 128
          l.r = 67
          l.g = 82
          l.b = 61
          l.a = 255
        else
          l.a = 0
        end
      end

      @args.outputs.borders << {
        x: NOKIA_X_OFFSET      - 1,
        y: NOKIA_Y_OFFSET      - 1,
        w: NOKIA_ZOOMED_WIDTH  + 2,
        h: NOKIA_ZOOMED_HEIGHT + 2,
        r: 128, g: 128, b: 128
      }


      @args.outputs.background_color = [199, 240, 216]

      @args.outputs.solids << [0, 0, NOKIA_X_OFFSET, 720]
      @args.outputs.solids << [0, 0, 1280, NOKIA_Y_OFFSET]
      @args.outputs.solids << [NOKIA_X_OFFSET + NOKIA_ZOOMED_WIDTH, 0, NOKIA_X_OFFSET, 720]
      @args.outputs.solids << [0, NOKIA_Y_OFFSET.from_top, 1280, NOKIA_Y_OFFSET]

      @args.outputs
           .sprites << { x: NOKIA_X_OFFSET,
                         y: NOKIA_Y_OFFSET,
                         w: NOKIA_ZOOMED_WIDTH,
                         h: NOKIA_ZOOMED_HEIGHT,
                         source_x: 0,
                         source_y: 0,
                         source_w: NOKIA_WIDTH,
                         source_h: NOKIA_HEIGHT,
                         path: :nokia }

      if [email protected]_rendered
        (NOKIA_HEIGHT + 1).map_with_index do |i|
          @args.outputs.static_lines << {
            x:  NOKIA_X_OFFSET,
            y:  NOKIA_Y_OFFSET + (i * NOKIA_ZOOM),
            x2: NOKIA_X_OFFSET + NOKIA_ZOOMED_WIDTH,
            y2: NOKIA_Y_OFFSET + (i * NOKIA_ZOOM),
            r: 199,
            g: 240,
            b: 216,
            a: 100
          }.line!
        end

        (NOKIA_WIDTH + 1).map_with_index do |i|
          @args.outputs.static_lines << {
            x:  NOKIA_X_OFFSET + (i * NOKIA_ZOOM),
            y:  NOKIA_Y_OFFSET,
            x2: NOKIA_X_OFFSET + (i * NOKIA_ZOOM),
            y2: NOKIA_Y_OFFSET + NOKIA_ZOOMED_HEIGHT,
            r: 199,
            g: 240,
            b: 216,
            a: 100
          }.line!
        end

        @args.state.overlay_rendered = true
      end
    end
  end
end

    Resolution 64x64 - lowrez.rb link

    # ./samples/99_genre_lowrez/resolution_64x64/app/lowrez.rb
# Emulation of a 64x64 canvas. Don't change this file unless you know what you're doing :-)
# Head over to main.rb and study the code there.

LOWREZ_SIZE            = 64
LOWREZ_ZOOM            = 10
LOWREZ_ZOOMED_SIZE     = LOWREZ_SIZE * LOWREZ_ZOOM
LOWREZ_X_OFFSET        = (1280 - LOWREZ_ZOOMED_SIZE).half
LOWREZ_Y_OFFSET        = ( 720 - LOWREZ_ZOOMED_SIZE).half

LOWREZ_FONT_XL         = -1
LOWREZ_FONT_XL_HEIGHT  = 20

LOWREZ_FONT_LG         = -3.5
LOWREZ_FONT_LG_HEIGHT  = 15

LOWREZ_FONT_MD         = -6
LOWREZ_FONT_MD_HEIGHT  = 10

LOWREZ_FONT_SM         = -8.5
LOWREZ_FONT_SM_HEIGHT  = 5

LOWREZ_FONT_PATH       = 'fonts/lowrez.ttf'


class LowrezOutputs
  attr_accessor :width, :height

  def initialize args
    @args = args
    @background_color ||= [0, 0, 0]
    @args.outputs.background_color = @background_color
  end

  def background_color
    @background_color ||= [0, 0, 0]
  end

  def background_color= opts
    @background_color = opts
    @args.outputs.background_color = @background_color

    outputs_lowrez.solids << [0, 0, LOWREZ_SIZE, LOWREZ_SIZE, @background_color]
  end

  def outputs_lowrez
    return @args.outputs if @args.state.tick_count <= 0
    return @args.outputs[:lowrez].transient!
  end

  def solids
    outputs_lowrez.solids
  end

  def borders
    outputs_lowrez.borders
  end

  def sprites
    outputs_lowrez.sprites
  end

  def labels
    outputs_lowrez.labels
  end

  def default_label
    {
      x: 0,
      y: 63,
      text: "",
      size_enum: LOWREZ_FONT_SM,
      alignment_enum: 0,
      r: 0,
      g: 0,
      b: 0,
      a: 255,
      font: LOWREZ_FONT_PATH
    }
  end

  def lines
    outputs_lowrez.lines
  end

  def primitives
    outputs_lowrez.primitives
  end

  def click
    return nil unless @args.inputs.mouse.click
    mouse
  end

  def mouse_click
    click
  end

  def mouse_down
    @args.inputs.mouse.down
  end

  def mouse_up
    @args.inputs.mouse.up
  end

  def mouse
    [
      ((@args.inputs.mouse.x - LOWREZ_X_OFFSET).idiv(LOWREZ_ZOOM)),
      ((@args.inputs.mouse.y - LOWREZ_Y_OFFSET).idiv(LOWREZ_ZOOM))
    ]
  end

  def mouse_position
    mouse
  end

  def keyboard
    @args.inputs.keyboard
  end
end

class GTK::Args
  def init_lowrez
    return if @lowrez
    @lowrez = LowrezOutputs.new self
  end

  def lowrez
    @lowrez
  end
end

module GTK
  class Runtime
    alias_method :__original_tick_core__, :tick_core unless Runtime.instance_methods.include?(:__original_tick_core__)

    def tick_core
      @args.init_lowrez
      __original_tick_core__

      return if @args.state.tick_count <= 0

      @args.render_target(:lowrez)
           .labels
           .each do |l|
        l.y  += 1
      end

      @args.render_target(:lowrez)
           .lines
           .each do |l|
        l.y  += 1
        l.y2 += 1
        l.y2 += 1 if l.y1 != l.y2
        l.x2 += 1 if l.x1 != l.x2
      end

      @args.outputs
           .sprites << { x: 320,
                         y: 40,
                         w: 640,
                         h: 640,
                         source_x: 0,
                         source_y: 0,
                         source_w: 64,
                         source_h: 64,
                         path: :lowrez }
    end
  end
end

    Resolution 64x64 - main.rb link

    # ./samples/99_genre_lowrez/resolution_64x64/app/main.rb
require 'app/lowrez.rb'

def tick args
  # How to set the background color
  args.lowrez.background_color = [255, 255, 255]

  # ==== HELLO WORLD ======================================================
  # Steps to get started:
  # 1. ~def tick args~ is the entry point for your game.
  # 2. There are quite a few code samples below, remove the "##"
  #    before each line and save the file to see the changes.
  # 3. 0,  0 is in bottom left and 63, 63 is in top right corner.
  # 4. Be sure to come to the discord channel if you need
  #    more help: [[http://discord.dragonruby.org]].

  # Commenting and uncommenting code:
  # - Add a "#" infront of lines to comment out code
  # - Remove the "#" infront of lines to comment out code

  # Invoke the hello_world subroutine/method
  hello_world args # <---- add a "#" to the beginning of the line to stop running this subroutine/method.
  # =======================================================================


  # ==== HOW TO RENDER A LABEL ============================================
  # Uncomment the line below to invoke the how_to_render_a_label subroutine/method.
  # Note: The method is defined in this file with the signature ~def how_to_render_a_label args~
  #       Scroll down to the method to see the details.

  # Remove the "#" at the beginning of the line below
  # how_to_render_a_label args # <---- remove the "#" at the begging of this line to run the method
  # =======================================================================


  # ==== HOW TO RENDER A FILLED SQUARE (SOLID) ============================
  # Remove the "#" at the beginning of the line below
  # how_to_render_solids args
  # =======================================================================


  # ==== HOW TO RENDER AN UNFILLED SQUARE (BORDER) ========================
  # Remove the "#" at the beginning of the line below
  # how_to_render_borders args
  # =======================================================================


  # ==== HOW TO RENDER A LINE =============================================
  # Remove the "#" at the beginning of the line below
  # how_to_render_lines args
  # =======================================================================


  # == HOW TO RENDER A SPRITE =============================================
  # Remove the "#" at the beginning of the line below
  # how_to_render_sprites args
  # =======================================================================


  # ==== HOW TO MOVE A SPRITE BASED OFF OF USER INPUT =====================
  # Remove the "#" at the beginning of the line below
  # how_to_move_a_sprite args
  # =======================================================================


  # ==== HOW TO ANIMATE A SPRITE (SEPERATE PNGS) ==========================
  # Remove the "#" at the beginning of the line below
  # how_to_animate_a_sprite args
  # =======================================================================


  # ==== HOW TO ANIMATE A SPRITE (SPRITE SHEET) ===========================
  # Remove the "#" at the beginning of the line below
  # how_to_animate_a_sprite_sheet args
  # =======================================================================


  # ==== HOW TO DETERMINE COLLISION =============================================
  # Remove the "#" at the beginning of the line below
  # how_to_determine_collision args
  # =======================================================================


  # ==== HOW TO CREATE BUTTONS ==================================================
  # Remove the "#" at the beginning of the line below
  # how_to_create_buttons args
  # =======================================================================


  # ==== The line below renders a debug grid, mouse information, and current tick
  render_debug args
end

def hello_world args
  args.lowrez.solids  << { x: 0, y: 64, w: 10, h: 10, r: 255 }

  args.lowrez.labels  << {
    x: 32,
    y: 63,
    text: "lowrezjam 2020",
    size_enum: LOWREZ_FONT_SM,
    alignment_enum: 1,
    r: 0,
    g: 0,
    b: 0,
    a: 255,
    font: LOWREZ_FONT_PATH
  }

  args.lowrez.sprites << {
    x: 32 - 10,
    y: 32 - 10,
    w: 20,
    h: 20,
    path: 'sprites/lowrez-ship-blue.png',
    a: args.state.tick_count % 255,
    angle: args.state.tick_count % 360
  }
end


# =======================================================================
# ==== HOW TO RENDER A LABEL ============================================
# =======================================================================
def how_to_render_a_label args
  # NOTE: Text is aligned from the TOP LEFT corner

  # Render an EXTRA LARGE/XL label (remove the "#" in front of each line below)
  args.lowrez.labels << { x: 0, y: 57, text: "Hello World",
                         size_enum: LOWREZ_FONT_XL,
                         r: 0, g: 0, b: 0, a: 255,
                         font: LOWREZ_FONT_PATH }

  # Render a LARGE/LG label (remove the "#" in front of each line below)
  args.lowrez.labels << { x: 0, y: 36, text: "Hello World",
                          size_enum: LOWREZ_FONT_LG,
                          r: 0, g: 0, b: 0, a: 255,
                          font: LOWREZ_FONT_PATH }

  # Render a MEDIUM/MD label (remove the "#" in front of each line below)
  args.lowrez.labels << { x: 0, y: 20, text: "Hello World",
                          size_enum: LOWREZ_FONT_MD,
                          r: 0, g: 0, b: 0, a: 255,
                          font: LOWREZ_FONT_PATH }

  # Render a SMALL/SM label (remove the "#" in front of each line below)
  args.lowrez.labels << { x: 0, y: 9, text: "Hello World",
                          size_enum: LOWREZ_FONT_SM,
                          r: 0, g: 0, b: 0, a: 255,
                          font: LOWREZ_FONT_PATH }

  # You are provided args.lowrez.default_label which returns a Hash that you
  # can ~merge~ properties with
  # Example 1
  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(text: "Default")

  # Example 2
  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 31,
                                   text: "Default",
                                   r: 128,
                                   g: 128,
                                   b: 128)
end

## # =============================================================================
## # ==== HOW TO RENDER FILLED SQUARES (SOLIDS) ==================================
## # =============================================================================
def how_to_render_solids args
  # Render a red square at 0, 0 with a width and height of 1
  args.lowrez.solids << { x: 0, y: 0, w: 1, h: 1, r: 255, g: 0, b: 0, a: 255 }

  # Render a red square at 1, 1 with a width and height of 2
  args.lowrez.solids << { x: 1, y: 1, w: 2, h: 2, r: 255, g: 0, b: 0, a: 255 }

  # Render a red square at 3, 3 with a width and height of 3
  args.lowrez.solids << { x: 3, y: 3, w: 3, h: 3, r: 255, g: 0, b: 0 }

  # Render a red square at 6, 6 with a width and height of 4
  args.lowrez.solids << { x: 6, y: 6, w: 4, h: 4, r: 255, g: 0, b: 0 }
end

## # =============================================================================
## # ==== HOW TO RENDER UNFILLED SQUARES (BORDERS) ===============================
## # =============================================================================
def how_to_render_borders args
  # Render a red square at 0, 0 with a width and height of 3
  args.lowrez.borders << { x: 0, y: 0, w: 3, h: 3, r: 255, g: 0, b: 0, a: 255 }

  # Render a red square at 3, 3 with a width and height of 3
  args.lowrez.borders << { x: 3, y: 3, w: 4, h: 4, r: 255, g: 0, b: 0, a: 255 }

  # Render a red square at 5, 5 with a width and height of 4
  args.lowrez.borders << { x: 7, y: 7, w: 5, h: 5, r: 255, g: 0, b: 0, a: 255 }
end

## # =============================================================================
## # ==== HOW TO RENDER A LINE ===================================================
## # =============================================================================
def how_to_render_lines args
  # Render a horizontal line at the bottom
  args.lowrez.lines << { x: 0, y: 0, x2: 63, y2:  0, r: 255 }

  # Render a vertical line at the left
  args.lowrez.lines << { x: 0, y: 0, x2:  0, y2: 63, r: 255 }

  # Render a diagonal line starting from the bottom left and going to the top right
  args.lowrez.lines << { x: 0, y: 0, x2: 63, y2: 63, r: 255 }
end

## # =============================================================================
## # == HOW TO RENDER A SPRITE ===================================================
## # =============================================================================
def how_to_render_sprites args
  # Loop 10 times and create 10 sprites in 10 positions
  # Render a sprite at the bottom left with a width and height of 5 and a path of 'sprites/lowrez-ship-blue.png'
  10.times do |i|
    args.lowrez.sprites << {
      x: i * 5,
      y: i * 5,
      w: 5,
      h: 5,
      path: 'sprites/lowrez-ship-blue.png'
    }
  end

  # Given an array of positions create sprites
  positions = [
    { x: 10, y: 42 },
    { x: 15, y: 45 },
    { x: 22, y: 33 },
  ]

  positions.each do |position|
    # use Ruby's ~Hash#merge~ function to create a sprite
    args.lowrez.sprites << position.merge(path: 'sprites/lowrez-ship-red.png',
                                          w: 5,
                                          h: 5)
  end
end

## # =============================================================================
## # ==== HOW TO ANIMATE A SPRITE (SEPERATE PNGS) ==========================
## # =============================================================================
def how_to_animate_a_sprite args
  # STEP 1: Define when you want the animation to start. The animation in this case will start in 3 seconds
  start_animation_on_tick = 180

  # STEP 2: Get the frame_index given the start tick.
  sprite_index = start_animation_on_tick.frame_index count: 7,     # how many sprites?
                                                     hold_for: 4,  # how long to hold each sprite?
                                                     repeat: true  # should it repeat?

  # STEP 3: frame_index will return nil if the frame hasn't arrived yet
  if sprite_index
    # if the sprite_index is populated, use it to determine the sprite path and render it
    sprite_path  = "sprites/explosion-#{sprite_index}.png"
    args.lowrez.sprites << { x: 0, y: 0, w: 64, h: 64, path: sprite_path }
  else
    # if the sprite_index is nil, render a countdown instead
    countdown_in_seconds = ((start_animation_on_tick - args.state.tick_count) / 60).round(1)

    args.lowrez.labels  << args.lowrez
                               .default_label
                               .merge(x: 32,
                                      y: 32,
                                      text: "Count Down: #{countdown_in_seconds}",
                                      alignment_enum: 1)
  end

  # render the current tick and the resolved sprite index
  args.lowrez.labels  << args.lowrez
                               .default_label
                               .merge(x: 0,
                                      y: 11,
                                      text: "Tick: #{args.state.tick_count}")
  args.lowrez.labels  << args.lowrez
                               .default_label
                               .merge(x: 0,
                                      y: 5,
                                      text: "sprite_index: #{sprite_index}")
end

## # =============================================================================
## # ==== HOW TO ANIMATE A SPRITE (SPRITE SHEET) =================================
## # =============================================================================
def how_to_animate_a_sprite_sheet args
  # STEP 1: Define when you want the animation to start. The animation in this case will start in 3 seconds
  start_animation_on_tick = 180

  # STEP 2: Get the frame_index given the start tick.
  sprite_index = start_animation_on_tick.frame_index count: 7,     # how many sprites?
                                                     hold_for: 4,  # how long to hold each sprite?
                                                     repeat: true  # should it repeat?

  # STEP 3: frame_index will return nil if the frame hasn't arrived yet
  if sprite_index
    # if the sprite_index is populated, use it to determine the source rectangle and render it
    args.lowrez.sprites << {
      x: 0,
      y: 0,
      w: 64,
      h: 64,
      path:  "sprites/explosion-sheet.png",
      source_x: 32 * sprite_index,
      source_y: 0,
      source_w: 32,
      source_h: 32
    }
  else
    # if the sprite_index is nil, render a countdown instead
    countdown_in_seconds = ((start_animation_on_tick - args.state.tick_count) / 60).round(1)

    args.lowrez.labels  << args.lowrez
                               .default_label
                               .merge(x: 32,
                                      y: 32,
                                      text: "Count Down: #{countdown_in_seconds}",
                                      alignment_enum: 1)
  end

  # render the current tick and the resolved sprite index
  args.lowrez.labels  << args.lowrez
                               .default_label
                               .merge(x: 0,
                                      y: 11,
                                      text: "tick: #{args.state.tick_count}")
  args.lowrez.labels  << args.lowrez
                               .default_label
                               .merge(x: 0,
                                      y: 5,
                                      text: "sprite_index: #{sprite_index}")
end

## # =============================================================================
## # ==== HOW TO STORE STATE, ACCEPT INPUT, AND RENDER SPRITE BASED OFF OF STATE =
## # =============================================================================
def how_to_move_a_sprite args
  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 32,
                                   y: 62, text: "Use Arrow Keys",
                                   alignment_enum: 1)

  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 32,
                                   y: 56, text: "Use WASD",
                                   alignment_enum: 1)

  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 32,
                                   y: 50, text: "Or Click",
                                   alignment_enum: 1)

  # set the initial values for x and y using ||= ("or equal operator")
  args.state.ship.x ||= 0
  args.state.ship.y ||= 0

  # if a mouse click occurs, update the ship's x and y to be the location of the click
  if args.lowrez.mouse_click
    args.state.ship.x = args.lowrez.mouse_click.x
    args.state.ship.y = args.lowrez.mouse_click.y
  end

  # if a or left arrow is pressed/held, decrement the ships x position
  if args.lowrez.keyboard.left
    args.state.ship.x -= 1
  end

  # if d or right arrow is pressed/held, increment the ships x position
  if args.lowrez.keyboard.right
    args.state.ship.x += 1
  end

  # if s or down arrow is pressed/held, decrement the ships y position
  if args.lowrez.keyboard.down
    args.state.ship.y -= 1
  end

  # if w or up arrow is pressed/held, increment the ships y position
  if args.lowrez.keyboard.up
    args.state.ship.y += 1
  end

  # render the sprite to the screen using the position stored in args.state.ship
  args.lowrez.sprites << {
    x: args.state.ship.x,
    y: args.state.ship.y,
    w: 5,
    h: 5,
    path: 'sprites/lowrez-ship-blue.png',
    # parameters beyond this point are optional
    angle: 0, # Note: rotation angle is denoted in degrees NOT radians
    r: 255,
    g: 255,
    b: 255,
    a: 255
  }
end

# =======================================================================
# ==== HOW TO DETERMINE COLLISION =======================================
# =======================================================================
def how_to_determine_collision args
  # Render the instructions
  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 32,
                                   y: 62, text: "Click Anywhere",
                                   alignment_enum: 1)

  # if a mouse click occurs:
  # - set ship_one if it isn't set
  # - set ship_two if it isn't set
  # - otherwise reset ship one and ship two
  if args.lowrez.mouse_click
    # is ship_one set?
    if !args.state.ship_one
      args.state.ship_one = { x: args.lowrez.mouse_click.x - 10,
                              y: args.lowrez.mouse_click.y - 10,
                              w: 20,
                              h: 20 }
    # is ship_one set?
    elsif !args.state.ship_two
      args.state.ship_two = { x: args.lowrez.mouse_click.x - 10,
                              y: args.lowrez.mouse_click.y - 10,
                              w: 20,
                              h: 20 }
    # should we reset?
    else
      args.state.ship_one = nil
      args.state.ship_two = nil
    end
  end

  # render ship one if it's set
  if args.state.ship_one
    # use Ruby's .merge method which is available on ~Hash~ to set the sprite and alpha
    # render ship one
    args.lowrez.sprites << args.state.ship_one.merge(path: 'sprites/lowrez-ship-blue.png', a: 100)
  end

  if args.state.ship_two
    # use Ruby's .merge method which is available on ~Hash~ to set the sprite and alpha
    # render ship two
    args.lowrez.sprites << args.state.ship_two.merge(path: 'sprites/lowrez-ship-red.png', a: 100)
  end

  # if both ship one and ship two are set, then determine collision
  if args.state.ship_one && args.state.ship_two
    # collision is determined using the intersect_rect? method
    if args.state.ship_one.intersect_rect? args.state.ship_two
      # if collision occurred, render the words collision!
      args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 31,
                                   y: 5,
                                   text: "Collision!",
                                   alignment_enum: 1)
    else
      # if collision occurred, render the words no collision.
      args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 31,
                                   y: 5,
                                   text: "No Collision.",
                                   alignment_enum: 1)
    end
  else
    # if both ship one and ship two aren't set, then render --
      args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(x: 31,
                                   y: 6,
                                   text: "--",
                                   alignment_enum: 1)
  end
end

## # =============================================================================
## # ==== HOW TO CREATE BUTTONS ==================================================
## # =============================================================================
def how_to_create_buttons args
  # Define a button style
  args.state.button_style = { w: 62, h: 10, r: 80, g: 80, b: 80 }
  args.state.label_style  = { r: 80, g: 80, b: 80 }

  # Render instructions
  args.state.button_message ||= "Press a Button!"
  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(args.state.label_style)
                            .merge(x: 32,
                                   y: 62,
                                   text: args.state.button_message,
                                   alignment_enum: 1)


  # Creates button one using a border and a label
  args.state.button_one_border = args.state.button_style.merge( x: 1, y: 32)
  args.lowrez.borders << args.state.button_one_border
  args.lowrez.labels  << args.lowrez
                             .default_label
                             .merge(args.state.label_style)
                             .merge(x: args.state.button_one_border.x + 2,
                                    y: args.state.button_one_border.y + LOWREZ_FONT_SM_HEIGHT + 2,
                                    text: "Button One")

  # Creates button two using a border and a label
  args.state.button_two_border = args.state.button_style.merge( x: 1, y: 20)

  args.lowrez.borders << args.state.button_two_border
  args.lowrez.labels << args.lowrez
                            .default_label
                            .merge(args.state.label_style)
                            .merge(x: args.state.button_two_border.x + 2,
                                   y: args.state.button_two_border.y + LOWREZ_FONT_SM_HEIGHT + 2,
                                   text: "Button Two")

  # Initialize the state variable that tracks which button was clicked to "" (empty stringI
  args.state.last_button_clicked ||= "--"

  # If a click occurs, check to see if either button one, or button two was clicked
  # using the inside_rect? method of the mouse
  # set args.state.last_button_clicked accordingly
  if args.lowrez.mouse_click
    if args.lowrez.mouse_click.inside_rect? args.state.button_one_border
      args.state.last_button_clicked = "One Clicked!"
    elsif args.lowrez.mouse_click.inside_rect? args.state.button_two_border
      args.state.last_button_clicked = "Two Clicked!"
    else
      args.state.last_button_clicked = "--"
    end
  end

  # Render the current value of args.state.last_button_clicked
  args.lowrez.labels << args.lowrez
                             .default_label
                             .merge(args.state.label_style)
                             .merge(x: 32,
                                    y: 5,
                                    text: args.state.last_button_clicked,
                                    alignment_enum: 1)
end


def render_debug args
  if !args.state.grid_rendered
    65.map_with_index do |i|
      args.outputs.static_debug << {
        x:  LOWREZ_X_OFFSET,
        y:  LOWREZ_Y_OFFSET + (i * 10),
        x2: LOWREZ_X_OFFSET + LOWREZ_ZOOMED_SIZE,
        y2: LOWREZ_Y_OFFSET + (i * 10),
        r: 128,
        g: 128,
        b: 128,
        a: 80
      }.line!

      args.outputs.static_debug << {
        x:  LOWREZ_X_OFFSET + (i * 10),
        y:  LOWREZ_Y_OFFSET,
        x2: LOWREZ_X_OFFSET + (i * 10),
        y2: LOWREZ_Y_OFFSET + LOWREZ_ZOOMED_SIZE,
        r: 128,
        g: 128,
        b: 128,
        a: 80
      }.line!
    end
  end

  args.state.grid_rendered = true

  args.state.last_click ||= 0
  args.state.last_up    ||= 0
  args.state.last_click   = args.state.tick_count if args.lowrez.mouse_down # you can also use args.lowrez.click
  args.state.last_up      = args.state.tick_count if args.lowrez.mouse_up
  args.state.label_style  = { size_enum: -1.5 }

  args.state.watch_list = [
    "args.state.tick_count is:       #{args.state.tick_count}",
    "args.lowrez.mouse_position is:  #{args.lowrez.mouse_position.x}, #{args.lowrez.mouse_position.y}",
    "args.lowrez.mouse_down tick:    #{args.state.last_click || "never"}",
    "args.lowrez.mouse_up tick:      #{args.state.last_up || "false"}",
  ]

  args.outputs.debug << args.state
                            .watch_list
                            .map_with_index do |text, i|
    {
      x: 5,
      y: 720 - (i * 20),
      text: text,
      size_enum: -1.5
    }.label!
  end

  args.outputs.debug << {
    x: 640,
    y:  25,
    text: "INFO: dev mode is currently enabled. Comment out the invocation of ~render_debug~ within the ~tick~ method to hide the debug layer.",
    size_enum: -0.5,
    alignment_enum: 1
  }.label!
end

$gtk.reset

    Genre Mario link

    Jumping - main.rb link

    # ./samples/99_genre_mario/01_jumping/app/main.rb
def tick args
  defaults args
  render args
  input args
  calc args
end

def defaults args
  args.state.player.x      ||= args.grid.w.half
  args.state.player.y      ||= 0
  args.state.player.size   ||= 100
  args.state.player.dy     ||= 0
  args.state.player.action ||= :jumping
  args.state.jump.power           = 20
  args.state.jump.increase_frames = 10
  args.state.jump.increase_power  = 1
  args.state.gravity              = -1
end

def render args
  args.outputs.sprites << {
    x: args.state.player.x -
       args.state.player.size.half,
    y: args.state.player.y,
    w: args.state.player.size,
    h: args.state.player.size,
    path: 'sprites/square/red.png'
  }
end

def input args
  if args.inputs.keyboard.key_down.space
    if args.state.player.action == :standing
      args.state.player.action = :jumping
      args.state.player.dy = args.state.jump.power

      # record when the action took place
      current_frame = args.state.tick_count
      args.state.player.action_at = current_frame
    end
  end

  # if the space bar is being held
  if args.inputs.keyboard.key_held.space
    # is the player jumping
    is_jumping = args.state.player.action == :jumping

    # when was the jump performed
    time_of_jump = args.state.player.action_at

    # how much time has passed since the jump
    jump_elapsed_time = time_of_jump.elapsed_time

    # how much time is allowed for increasing power
    time_allowed = args.state.jump.increase_frames

    # if the player is jumping
    # and the elapsed time is less than
    # the allowed time
    if is_jumping && jump_elapsed_time < time_allowed
       # increase the dy by the increase power
       power_to_add = args.state.jump.increase_power
       args.state.player.dy += power_to_add
    end
  end
end

def calc args
  if args.state.player.action == :jumping
    args.state.player.y  += args.state.player.dy
    args.state.player.dy += args.state.gravity
  end

  if args.state.player.y < 0
    args.state.player.y      = 0
    args.state.player.action = :standing
  end
end

    Jumping And Collisions - main.rb link

    # ./samples/99_genre_mario/02_jumping_and_collisions/app/main.rb
class Game
  attr_gtk

  def tick
    defaults
    render
    input
    calc
  end

  def defaults
    return if state.tick_count != 0

    player.x                     = 64
    player.y                     = 800
    player.size                  = 50
    player.dx                    = 0
    player.dy                    = 0
    player.action                = :falling

    player.max_speed             = 20
    player.jump_power            = 15
    player.jump_air_time         = 15
    player.jump_increase_power   = 1

    state.gravity                = -1
    state.drag                   = 0.001
    state.tile_size              = 64
    state.tiles                ||= [
      { ordinal_x:  0, ordinal_y: 0 },
      { ordinal_x:  1, ordinal_y: 0 },
      { ordinal_x:  2, ordinal_y: 0 },
      { ordinal_x:  3, ordinal_y: 0 },
      { ordinal_x:  4, ordinal_y: 0 },
      { ordinal_x:  5, ordinal_y: 0 },
      { ordinal_x:  6, ordinal_y: 0 },
      { ordinal_x:  7, ordinal_y: 0 },
      { ordinal_x:  8, ordinal_y: 0 },
      { ordinal_x:  9, ordinal_y: 0 },
      { ordinal_x: 10, ordinal_y: 0 },
      { ordinal_x: 11, ordinal_y: 0 },
      { ordinal_x: 12, ordinal_y: 0 },

      { ordinal_x:  9, ordinal_y: 3 },
      { ordinal_x: 10, ordinal_y: 3 },
      { ordinal_x: 11, ordinal_y: 3 },
    ]

    tiles.each do |t|
      t.rect = { x: t.ordinal_x * 64,
                 y: t.ordinal_y * 64,
                 w: 64,
                 h: 64 }
    end
  end

  def render
    render_player
    render_tiles
    # render_grid
  end

  def input
    input_jump
    input_move
  end

  def calc
    calc_player_rect
    calc_left
    calc_right
    calc_below
    calc_above
    calc_player_dy
    calc_player_dx
    calc_game_over
  end

  def render_player
    outputs.sprites << {
      x: player.x,
      y: player.y,
      w: player.size,
      h: player.size,
      path: 'sprites/square/red.png'
    }
  end

  def render_tiles
    outputs.sprites << state.tiles.map do |t|
      t.merge path: 'sprites/square/white.png',
              x: t.ordinal_x * 64,
              y: t.ordinal_y * 64,
              w: 64,
              h: 64
    end
  end

  def render_grid
    if state.tick_count == 0
      outputs[:grid].transient!
      outputs[:grid].background_color = [0, 0, 0, 0]
      outputs[:grid].borders << available_brick_locations
      outputs[:grid].labels  << available_brick_locations.map do |b|
        [
          b.merge(text: "#{b.ordinal_x},#{b.ordinal_y}",
                  x: b.x + 2,
                  y: b.y + 2,
                  size_enum: -3,
                  vertical_alignment_enum: 0,
                  blendmode_enum: 0),
          b.merge(text: "#{b.x},#{b.y}",
                  x: b.x + 2,
                  y: b.y + 2 + 20,
                  size_enum: -3,
                  vertical_alignment_enum: 0,
                  blendmode_enum: 0)
        ]
      end
    end

    outputs.sprites << { x: 0, y: 0, w: 1280, h: 720, path: :grid }
  end

  def input_jump
    if inputs.keyboard.key_down.space
      player_jump
    end

    if inputs.keyboard.key_held.space
      player_jump_increase_air_time
    end
  end

  def input_move
    if player.dx.abs < 20
      if inputs.keyboard.left
        player.dx -= 2
      elsif inputs.keyboard.right
        player.dx += 2
      end
    end
  end

  def calc_game_over
    if player.y < -64
      player.x = 64
      player.y = 800
      player.dx = 0
      player.dy = 0
    end
  end

  def calc_player_rect
    player.rect      = player_current_rect
    player.next_rect = player_next_rect
    player.prev_rect = player_prev_rect
  end

  def calc_player_dx
    player.dx  = player_next_dx
    player.x  += player.dx
  end

  def calc_player_dy
    player.y  += player.dy
    player.dy  = player_next_dy
  end

  def calc_below
    return unless player.dy < 0
    tiles_below = tiles_find { |t| t.rect.top <= player.prev_rect.y }
    collision = tiles_find_colliding tiles_below, (player.rect.merge y: player.next_rect.y)
    if collision
      player.y  = collision.rect.y + state.tile_size
      player.dy = 0
      player.action = :standing
    else
      player.action = :falling
    end
  end

  def calc_left
    return unless player.dx < 0 && player_next_dx < 0
    tiles_left = tiles_find { |t| t.rect.right <= player.prev_rect.left }
    collision = tiles_find_colliding tiles_left, (player.rect.merge x: player.next_rect.x)
    return unless collision
    player.x  = collision.rect.right
    player.dx = 0
  end

  def calc_right
    return unless player.dx > 0 && player_next_dx > 0
    tiles_right = tiles_find { |t| t.rect.left >= player.prev_rect.right }
    collision = tiles_find_colliding tiles_right, (player.rect.merge x: player.next_rect.x)
    return unless collision
    player.x  = collision.rect.left - player.rect.w
    player.dx = 0
  end

  def calc_above
    return unless player.dy > 0
    tiles_above = tiles_find { |t| t.rect.y >= player.prev_rect.y }
    collision = tiles_find_colliding tiles_above, (player.rect.merge y: player.next_rect.y)
    return unless collision
    player.dy = 0
    player.y  = collision.rect.bottom - player.rect.h
  end

  def player_current_rect
    { x: player.x, y: player.y, w: player.size, h: player.size }
  end

  def available_brick_locations
    (0..19).to_a
      .product(0..11)
      .map do |(ordinal_x, ordinal_y)|
      { ordinal_x: ordinal_x,
        ordinal_y: ordinal_y,
        x: ordinal_x * 64,
        y: ordinal_y * 64,
        w: 64,
        h: 64 }
    end
  end

  def player
    state.player ||= args.state.new_entity :player
  end

  def player_next_dy
    player.dy + state.gravity + state.drag ** 2 * -1
  end

  def player_next_dx
    player.dx * 0.8
  end

  def player_next_rect
    player.rect.merge x: player.x + player_next_dx,
                      y: player.y + player_next_dy
  end

  def player_prev_rect
    player.rect.merge x: player.x - player.dx,
                      y: player.y - player.dy
  end

  def player_jump
    return if player.action != :standing
    player.action = :jumping
    player.dy = state.player.jump_power
    current_frame = state.tick_count
    player.action_at = current_frame
  end

  def player_jump_increase_air_time
    return if player.action != :jumping
    return if player.action_at.elapsed_time >= player.jump_air_time
    player.dy += player.jump_increase_power
  end

  def tiles
    state.tiles
  end

  def tiles_find_colliding tiles, target
    tiles.find { |t| t.rect.intersect_rect? target }
  end

  def tiles_find &block
    tiles.find_all(&block)
  end
end

def tick args
  $game ||= Game.new
  $game.args = args
  $game.tick
end

$gtk.reset

    Genre Platformer link

    Clepto Frog - main.rb link

    # ./samples/99_genre_platformer/clepto_frog/app/main.rb
class CleptoFrog
  attr_gtk

  def tick
    defaults
    render
    input
    calc
  end

  def defaults
    state.level_editor_rect_w ||= 32
    state.level_editor_rect_h     ||= 32
    state.target_camera_scale ||= 0.5
    state.camera_scale        ||= 1
    state.tongue_length       ||= 100
    state.action              ||= :aiming
    state.tongue_angle        ||= 90
    state.tile_size           ||= 32
    state.gravity             ||= -0.1
    state.drag                ||= -0.005
    state.player ||= {
      x: 2400,
      y: 200,
      w: 60,
      h: 60,
      dx: 0,
      dy: 0,
    }
    state.camera_x     ||= state.player.x - 640
    state.camera_y     ||= 0
    load_if_needed
    state.map_saved_at ||= 0
  end

  def player
    state.player
  end

  def render
    render_world
    render_player
    render_level_editor
    render_mini_map
    render_instructions
  end

  def to_camera_space rect
    rect.merge(x: to_camera_space_x(rect.x),
               y: to_camera_space_y(rect.y),
               w: to_camera_space_w(rect.w),
               h: to_camera_space_h(rect.h))
  end

  def to_camera_space_x x
    return nil if !x
     (x * state.camera_scale) - state.camera_x
  end

  def to_camera_space_y y
    return nil if !y
    (y * state.camera_scale) - state.camera_y
  end

  def to_camera_space_w w
    return nil if !w
    w * state.camera_scale
  end

  def to_camera_space_h h
    return nil if !h
    h * state.camera_scale
  end

  def render_world
    viewport = {
      x: player.x - 1280 / state.camera_scale,
      y: player.y - 720 / state.camera_scale,
      w: 2560 / state.camera_scale,
      h: 1440 / state.camera_scale
    }

    outputs.sprites << geometry.find_all_intersect_rect(viewport, state.mugs).map do |rect|
      to_camera_space rect
    end

    outputs.sprites << geometry.find_all_intersect_rect(viewport, state.walls).map do |rect|
      to_camera_space(rect).merge!(path: :pixel, r: 128, g: 128, b: 128, a: 128)
    end
  end

  def render_player
    start_of_tongue_render = to_camera_space start_of_tongue

    if state.anchor_point
      anchor_point_render = to_camera_space state.anchor_point
      outputs.sprites << { x: start_of_tongue_render.x - 2,
                           y: start_of_tongue_render.y - 2,
                           w: to_camera_space_w(4),
                           h: geometry.distance(start_of_tongue_render, anchor_point_render),
                           path:  :pixel,
                           angle_anchor_y: 0,
                           r: 255, g: 128, b: 128,
                           angle: state.tongue_angle - 90 }
    else
      outputs.sprites << { x: to_camera_space_x(start_of_tongue.x) - 2,
                           y: to_camera_space_y(start_of_tongue.y) - 2,
                           w: to_camera_space_w(4),
                           h: to_camera_space_h(state.tongue_length),
                           path:  :pixel,
                           r: 255, g: 128, b: 128,
                           angle_anchor_y: 0,
                           angle: state.tongue_angle - 90 }
    end

    angle = 0
    if state.action == :aiming && !player.on_floor
      angle = state.tongue_angle - 90
    elsif state.action == :shooting && !player.on_floor
      angle = state.tongue_angle - 90
    elsif state.action == :anchored
      angle = state.tongue_angle - 90
    end

    outputs.sprites << to_camera_space(player).merge!(path: "sprites/square/green.png", angle: angle)
  end

  def render_mini_map
    x, y = 1170, 10
    outputs.primitives << { x: x,
                            y: y,
                            w: 100,
                            h: 58,
                            r: 0,
                            g: 0,
                            b: 0,
                            a: 200,
                            path: :pixel }

    outputs.primitives << { x: x + player.x.fdiv(100) - 1,
                            y: y + player.y.fdiv(100) - 1,
                            w: 2,
                            h: 2,
                            r: 0,
                            g: 255,
                            b: 0,
                            path: :pixel }

    t_start = start_of_tongue
    t_end = end_of_tongue

    outputs.primitives << {
      x: x + t_start.x.fdiv(100),
      y: y + t_start.y.fdiv(100),
      x2: x + t_end.x.fdiv(100),
      y2: y + t_end.y.fdiv(100),
      r: 255, g: 255, b: 255
    }

    outputs.primitives << state.mugs.map do |o|
      { x: x + o.x.fdiv(100) - 1,
        y: y + o.y.fdiv(100) - 1,
        w: 2,
        h: 2,
        r: 200,
        g: 200,
        b: 0,
        path: :pixel }
    end
  end

  def render_level_editor
    return if !state.level_editor_mode
    if state.map_saved_at > 0 && state.map_saved_at.elapsed_time < 120
      outputs.primitives << { x: 920, y: 670, text: 'Map has been exported!', size_enum: 1, r: 0, g: 50, b: 100, a: 50 }
    end

    outputs.primitives << { x: to_camera_space_x(((state.camera_x + inputs.mouse.x) / state.camera_scale).ifloor(state.tile_size)),
                            y: to_camera_space_y(((state.camera_y + inputs.mouse.y) / state.camera_scale).ifloor(state.tile_size)),
                            w: to_camera_space_w(state.level_editor_rect_w),
                            h: to_camera_space_h(state.level_editor_rect_h), path: :pixel, a: 200, r: 180, g: 80, b: 200 }
  end

  def render_instructions
    if state.level_editor_mode
      outputs.labels << { x: 640,
                          y: 10.from_top,
                          text: "Click to place wall. HJKL to change wall size. X + click to remove wall. M + click to place mug. Arrow keys to move around.",
                          size_enum: -1,
                          anchor_x: 0.5 }
      outputs.labels << { x: 640,
                          y: 35.from_top,
                          text: " - and + to zoom in and out. 0 to reset camera to default zoom. G to exit level editor mode.",
                          size_enum: -1,
                          anchor_x: 0.5 }
    else
      outputs.labels << { x: 640,
                          y: 10.from_top,
                          text: "Left and Right to aim tongue. Space to shoot or release tongue. G to enter level editor mode.",
                          size_enum: -1,
                          anchor_x: 0.5 }

      outputs.labels << { x: 640,
                          y: 35.from_top,
                          text: "Up and Down to change tongue length (when tongue is attached). Left and Right to swing (when tongue is attached).",
                          size_enum: -1,
                          anchor_x: 0.5 }
    end
  end

  def start_of_tongue
    {
      x: player.x + player.w / 2,
      y: player.y + player.h / 2
    }
  end

  def calc
    calc_camera
    calc_player
    calc_mug_collection
  end

  def calc_camera
    percentage = 0.2 * state.camera_scale
    target_scale = state.target_camera_scale
    distance_scale = target_scale - state.camera_scale
    state.camera_scale += distance_scale * percentage

    target_x = player.x * state.target_camera_scale
    target_y = player.y * state.target_camera_scale

    distance_x = target_x - (state.camera_x + 640)
    distance_y = target_y - (state.camera_y + 360)
    state.camera_x += distance_x * percentage if distance_x.abs > 1
    state.camera_y += distance_y * percentage if distance_y.abs > 1
    state.camera_x = 0 if state.camera_x < 0
    state.camera_y = 0 if state.camera_y < 0
  end

  def calc_player
    calc_shooting
    calc_swing
    calc_aabb_collision
    calc_tongue_angle
    calc_on_floor
  end

  def calc_shooting
    calc_shooting_step
    calc_shooting_step
    calc_shooting_step
    calc_shooting_step
    calc_shooting_step
    calc_shooting_step
  end

  def calc_shooting_step
    return unless state.action == :shooting
    state.tongue_length += 5
    potential_anchor = end_of_tongue
    anchor_rect = { x: potential_anchor.x - 5, y: potential_anchor.y - 5, w: 10, h: 10 }
    collision = state.walls.find_all do |v|
      v.intersect_rect?(anchor_rect)
    end.first
    if collision
      state.anchor_point = potential_anchor
      state.action = :anchored
    end
  end

  def calc_swing
    return if !state.anchor_point
    target_x = state.anchor_point.x - start_of_tongue.x
    target_y = state.anchor_point.y -
               state.tongue_length - 5 - 20 - player.h

    diff_y = player.y - target_y

    distance = geometry.distance(player, state.anchor_point)
    pull_strength = if distance < 100
                      0
                    else
                      (distance / 800)
                    end

    vector = state.tongue_angle.to_vector

    player.dx += vector.x * pull_strength**2
    player.dy += vector.y * pull_strength**2
  end

  def calc_aabb_collision
    return if !state.walls

    player.dx = player.dx.clamp(-30, 30)
    player.dy = player.dy.clamp(-30, 30)

    player.dx += player.dx * state.drag
    player.x += player.dx

    collision = geometry.find_intersect_rect player, state.walls

    if collision
      if player.dx > 0
        player.x = collision.x - player.w
      elsif player.dx < 0
        player.x = collision.x + collision.w
      end
      player.dx *= -0.8
    end

    if !state.level_editor_mode
      player.dy += state.gravity  # Since acceleration is the change in velocity, the change in y (dy) increases every frame
      player.y += player.dy
    end

    collision = geometry.find_intersect_rect player, state.walls

    if collision
      if player.dy > 0
        player.y = collision.y - 60
      elsif player.dy < 0
        player.y = collision.y + collision.h
      end

      player.dy *= -0.8
    end
  end

  def calc_tongue_angle
    return unless state.anchor_point
    state.tongue_angle = geometry.angle_from state.anchor_point, start_of_tongue
    state.tongue_length = geometry.distance(start_of_tongue, state.anchor_point)
    state.tongue_length = state.tongue_length.greater(100)
  end

  def calc_on_floor
    if state.action == :anchored
      player.on_floor = false
      player.on_floor_debounce = 30
    else
      player.on_floor_debounce ||= 30

      if player.dy.round != 0
        player.on_floor_debounce = 30
        player.on_floor = false
      else
        player.on_floor_debounce -= 1
      end

      if player.on_floor_debounce <= 0
        player.on_floor_debounce = 0
        player.on_floor = true
      end
    end
  end

  def calc_mug_collection
    collected = state.mugs.find_all { |s| s.intersect_rect? player }
    state.mugs.reject! { |s| collected.include? s }
  end

  def set_camera_scale v = nil
    return if v < 0.1
    state.target_camera_scale = v
  end

  def input
    input_game
    input_level_editor
  end

  def input_up?
    inputs.keyboard.w || inputs.keyboard.up
  end

  def input_down?
    inputs.keyboard.s || inputs.keyboard.down
  end

  def input_left?
    inputs.keyboard.a || inputs.keyboard.left
  end

  def input_right?
    inputs.keyboard.d || inputs.keyboard.right
  end

  def input_game
    if inputs.keyboard.key_down.g
      state.level_editor_mode = !state.level_editor_mode
    end

    if player.on_floor
      if inputs.keyboard.q
        player.dx = -5
      elsif inputs.keyboard.e
        player.dx = 5
      end
    end

    if inputs.keyboard.key_down.space && !state.anchor_point
      state.tongue_length = 0
      state.action = :shooting
    elsif inputs.keyboard.key_down.space
      state.action = :aiming
      state.anchor_point  = nil
      state.tongue_length = 100
    end

    if state.anchor_point
      vector = state.tongue_angle.to_vector

      if input_up?
        state.tongue_length -= 5
        player.dy += vector.y
        player.dx += vector.x
      elsif input_down?
        state.tongue_length += 5
        player.dy -= vector.y
        player.dx -= vector.x
      end

      if input_left?
        player.dx -= 0.5
      elsif input_right?
        player.dx += 0.5
      end
    else
      if input_left?
        state.tongue_angle += 1.5
        state.tongue_angle = state.tongue_angle
      elsif input_right?
        state.tongue_angle -= 1.5
        state.tongue_angle = state.tongue_angle
      end
    end
  end

  def input_level_editor
    return unless state.level_editor_mode

    if state.tick_count.mod_zero?(5)
      # zoom
      if inputs.keyboard.equal_sign || inputs.keyboard.plus
        set_camera_scale state.camera_scale + 0.1
      elsif inputs.keyboard.hyphen
        set_camera_scale state.camera_scale - 0.1
      elsif inputs.keyboard.zero
        set_camera_scale 0.5
      end

      # change wall width
      if inputs.keyboard.h
        state.level_editor_rect_w -= state.tile_size
      elsif inputs.keyboard.l
        state.level_editor_rect_w += state.tile_size
      end

      state.level_editor_rect_w = state.tile_size if state.level_editor_rect_w < state.tile_size

      # change wall height
      if inputs.keyboard.j
        state.level_editor_rect_h -= state.tile_size
      elsif inputs.keyboard.k
        state.level_editor_rect_h += state.tile_size
      end

      state.level_editor_rect_h = state.tile_size if state.level_editor_rect_h < state.tile_size
    end

    if inputs.mouse.click
      x = ((state.camera_x + inputs.mouse.x) / state.camera_scale).ifloor(state.tile_size)
      y = ((state.camera_y + inputs.mouse.y) / state.camera_scale).ifloor(state.tile_size)
      # place mug
      if inputs.keyboard.m
        w = 32
        h = 32
        candidate_rect = { x: x, y: y, w: w, h: h }
        if inputs.keyboard.x
          mouse_rect = { x: (state.camera_x + inputs.mouse.x) / state.camera_scale,
                         y: (state.camera_y + inputs.mouse.y) / state.camera_scale,
                         w: 10,
                         h: 10 }
          to_remove = state.mugs.find do |r|
            r.intersect_rect? mouse_rect
          end
          if to_remove
            state.mugs.reject! { |r| r == to_remove }
          end
        else
          exists = state.mugs.find { |r| r == candidate_rect }
          if !exists
            state.mugs << candidate_rect.merge(path: "sprites/square/orange.png")
          end
        end
      else
        # place wall
        w = state.level_editor_rect_w
        h = state.level_editor_rect_h
        candidate_rect = { x: x, y: y, w: w, h: h }
        if inputs.keyboard.x
          mouse_rect = { x: (state.camera_x + inputs.mouse.x) / state.camera_scale,
                         y: (state.camera_y + inputs.mouse.y) / state.camera_scale,
                         w: 10,
                         h: 10 }
          to_remove = state.walls.find do |r|
            r.intersect_rect? mouse_rect
          end
          if to_remove
            state.walls.reject! { |r| r == to_remove }
          end
        else
          exists = state.walls.find { |r| r == candidate_rect }
          if !exists
            state.walls << candidate_rect
          end
        end
      end

      save
    end

    if input_up?
      player.y += 10
      player.dy = 0
    elsif input_down?
      player.y -= 10
      player.dy = 0
    end

    if input_left?
      player.x -= 10
      player.dx = 0
    elsif input_right?
      player.x += 10
      player.dx = 0
    end
  end

  def end_of_tongue
    p = state.tongue_angle.to_vector
    { x: start_of_tongue.x + p.x * state.tongue_length,
      y: start_of_tongue.y + p.y * state.tongue_length }
  end

  def save
    $gtk.write_file("data/mugs.txt", "")
    state.mugs.each do |o|
      $gtk.append_file "data/mugs.txt", "#{o.x},#{o.y},#{o.w},#{o.h}\n"
    end

    $gtk.write_file("data/walls.txt", "")
    state.walls.map do |o|
      $gtk.append_file "data/walls.txt", "#{o.x},#{o.y},#{o.w},#{o.h}\n"
    end
  end

  def load_if_needed
    return if state.walls
    state.walls = []
    state.mugs = []

    contents = $gtk.read_file "data/mugs.txt"
    if contents
      contents.each_line do |l|
        x, y, w, h = l.split(',').map(&:to_i)
        state.mugs << { x: x.ifloor(state.tile_size),
                        y: y.ifloor(state.tile_size),
                        w: w,
                        h: h,
                        path: "sprites/square/orange.png" }
      end
    end

    contents = $gtk.read_file "data/walls.txt"
    if contents
      contents.each_line do |l|
        x, y, w, h = l.split(',').map(&:to_i)
        state.walls << { x: x.ifloor(state.tile_size),
                         y: y.ifloor(state.tile_size),
                         w: w,
                         h: h,
                         path: :pixel,
                         r: 128,
                         g: 128,
                         b: 128,
                         a: 128 }
      end
    end
  end
end

$game = CleptoFrog.new

def tick args
  $game.args = args
  $game.tick
end

# $gtk.reset

    Clepto Frog - Data - mugs.txt link

    # ./samples/99_genre_platformer/clepto_frog/data/mugs.txt
64,64,32,32
928,1952,32,32
3744,2464,32,32
1536,3264,32,32
7648,32,32,32
9312,1120,32,32
7296,1152,32,32
5792,1824,32,32
864,3744,32,32
1024,4640,32,32
800,5312,32,32
3232,5216,32,32
4736,5280,32,32
9312,5152,32,32
9632,4288,32,32
7808,4096,32,32
8640,1952,32,32
6880,2016,32,32
4608,3872,32,32
4000,4544,32,32
3200,3328,32,32
5056,1056,32,32
3424,608,32,32
6496,288,32,32
6080,288,32,32
5600,288,32,32
3424,608,32,32
2656,704,32,32
2208,224,32,32

    Clepto Frog - Data - walls.txt link

    # ./samples/99_genre_platformer/clepto_frog/data/walls.txt
0,0,32,5664
0,5664,10016,32
0,0,10016,32
10016,0,32,5696
2112,192,704,32
2112,672,704,32
3328,576,224,32
5504,256,256,32
5984,256,256,32
6400,256,256,32
4928,1024,256,32
7168,1120,256,32
9216,1088,256,32
8544,1920,256,32
6752,1984,256,32
5664,1792,256,32
832,1920,256,32
1440,3232,256,32
736,3712,256,32
896,4608,256,32
672,5280,256,32
3136,5184,256,32
3872,4512,256,32
4640,5248,256,32
7680,4064,256,32
9536,4256,256,32
9184,5120,256,32
3072,3296,256,32
3616,2432,256,32
4480,3840,256,32
4704,1952,128,128
6272,3328,128,128
5248,4832,128,128
2496,4320,128,128
1536,5056,128,128
7232,5024,128,128
2208,2336,128,128
1120,704,128,128
8448,2944,128,128
8576,4608,128,128
7840,2176,128,128
8640,416,128,128
6048,1088,128,128
4768,352,128,128
3040,1600,128,128
448,2720,128,128
1568,4064,128,128
256,4736,128,128
3936,5312,128,128
3872,3360,128,128
7904,800,128,128
6272,4320,128,128
1728,1440,128,128
96,768,128,128
9120,3616,128,128
6144,5184,128,128
7168,3168,128,128
5472,3712,128,128
2592,5088,128,128
2528,3328,128,128
1376,2560,128,128
4096,1344,128,128
9344,2336,128,128
5952,2656,128,128
3360,4160,128,128
224,1696,128,128
352,4064,128,128
8192,5248,128,128
7168,448,128,128
6624,2592,128,128
4608,2848,128,128
2336,1184,128,128
640,224,128,128
7264,4352,128,128

    Gorillas Basic - credits.txt link

    # ./samples/99_genre_platformer/gorillas_basic/CREDITS.txt
code: Amir Rajan, https://twitter.com/amirrajan
graphics: Nick Culbertson, https://twitter.com/MobyPixel

    Gorillas Basic - main.rb link

    # ./samples/99_genre_platformer/gorillas_basic/app/main.rb
class YouSoBasicGorillas
  attr_accessor :outputs, :grid, :state, :inputs

  def tick
    defaults
    render
    calc
    process_inputs
  end

  def defaults
    outputs.background_color = [33, 32, 87]
    state.building_spacing       = 1
    state.building_room_spacing  = 15
    state.building_room_width    = 10
    state.building_room_height   = 15
    state.building_heights       = [4, 4, 6, 8, 15, 20, 18]
    state.building_room_sizes    = [5, 4, 6, 7]
    state.gravity                = 0.25
    state.first_strike         ||= :player_1
    state.buildings            ||= []
    state.holes                ||= []
    state.player_1_score       ||= 0
    state.player_2_score       ||= 0
    state.wind                 ||= 0
  end

  def render
    render_stage
    render_value_insertion
    render_gorillas
    render_holes
    render_banana
    render_game_over
    render_score
    render_wind
  end

  def render_score
    outputs.primitives << [0, 0, 1280, 31, fancy_white].solid
    outputs.primitives << [1, 1, 1279, 29].solid
    outputs.labels << [  10, 25, "Score: #{state.player_1_score}", 0, 0, fancy_white]
    outputs.labels << [1270, 25, "Score: #{state.player_2_score}", 0, 2, fancy_white]
  end

  def render_wind
    outputs.primitives << [640, 12, state.wind * 500 + state.wind * 10 * rand, 4, 35, 136, 162].solid
    outputs.lines     <<  [640, 30, 640, 0, fancy_white]
  end

  def render_game_over
    return unless state.over
    outputs.primitives << [grid.rect, 0, 0, 0, 200].solid
    outputs.primitives << [640, 370, "Game Over!!", 5, 1, fancy_white].label
    if state.winner == :player_1
      outputs.primitives << [640, 340, "Player 1 Wins!!", 5, 1, fancy_white].label
    else
      outputs.primitives << [640, 340, "Player 2 Wins!!", 5, 1, fancy_white].label
    end
  end

  def render_stage
    return unless state.stage_generated
    return if state.stage_rendered

    outputs.static_solids << [grid.rect, 33, 32, 87]
    outputs.static_solids << state.buildings.map(&:solids)
    state.stage_rendered = true
  end

  def render_gorilla gorilla, id
    return unless gorilla
    if state.banana && state.banana.owner == gorilla
      animation_index  = state.banana.created_at.frame_index(3, 5, false)
    end
    if !animation_index
      outputs.sprites << [gorilla.solid, "sprites/#{id}-idle.png"]
    else
      outputs.sprites << [gorilla.solid, "sprites/#{id}-#{animation_index}.png"]
    end
  end

  def render_gorillas
    render_gorilla state.player_1, :left
    render_gorilla state.player_2, :right
  end

  def render_value_insertion
    return if state.banana
    return if state.over

    if    state.current_turn == :player_1_angle
      outputs.labels << [  10, 710, "Angle:    #{state.player_1_angle}_",    fancy_white]
    elsif state.current_turn == :player_1_velocity
      outputs.labels << [  10, 710, "Angle:    #{state.player_1_angle}",     fancy_white]
      outputs.labels << [  10, 690, "Velocity: #{state.player_1_velocity}_", fancy_white]
    elsif state.current_turn == :player_2_angle
      outputs.labels << [1120, 710, "Angle:    #{state.player_2_angle}_",    fancy_white]
    elsif state.current_turn == :player_2_velocity
      outputs.labels << [1120, 710, "Angle:    #{state.player_2_angle}",     fancy_white]
      outputs.labels << [1120, 690, "Velocity: #{state.player_2_velocity}_", fancy_white]
    end
  end

  def render_banana
    return unless state.banana
    rotation = state.tick_count.%(360) * 20
    rotation *= -1 if state.banana.dx > 0
    outputs.sprites << [state.banana.x, state.banana.y, 15, 15, 'sprites/banana.png', rotation]
  end

  def render_holes
    outputs.sprites << state.holes.map do |s|
      animation_index = s.created_at.frame_index(7, 3, false)
      if animation_index
        [s.sprite, [s.sprite.rect, "sprites/explosion#{animation_index}.png" ]]
      else
        s.sprite
      end
    end
  end

  def calc
    calc_generate_stage
    calc_current_turn
    calc_banana
  end

  def calc_current_turn
    return if state.current_turn

    state.current_turn = :player_1_angle
    state.current_turn = :player_2_angle if state.first_strike == :player_2
  end

  def calc_generate_stage
    return if state.stage_generated

    state.buildings << building_prefab(state.building_spacing + -20, *random_building_size)
    8.numbers.inject(state.buildings) do |buildings, i|
      buildings <<
        building_prefab(state.building_spacing +
                        state.buildings.last.right,
                        *random_building_size)
    end

    building_two = state.buildings[1]
    state.player_1 = new_player(building_two.x + building_two.w.fdiv(2),
                               building_two.h)

    building_nine = state.buildings[-3]
    state.player_2 = new_player(building_nine.x + building_nine.w.fdiv(2),
                               building_nine.h)
    state.stage_generated = true
    state.wind = 1.randomize(:ratio, :sign)
  end

  def new_player x, y
    state.new_entity(:gorilla) do |p|
      p.x = x - 25
      p.y = y
      p.solid = [p.x, p.y, 50, 50]
    end
  end

  def calc_banana
    return unless state.banana

    state.banana.x  += state.banana.dx
    state.banana.dx += state.wind.fdiv(50)
    state.banana.y  += state.banana.dy
    state.banana.dy -= state.gravity
    banana_collision = [state.banana.x, state.banana.y, 10, 10]

    if state.player_1 && banana_collision.intersect_rect?(state.player_1.solid)
      state.over = true
      if state.banana.owner == state.player_2
        state.winner = :player_2
      else
        state.winner = :player_1
      end

      state.player_2_score += 1
    elsif state.player_2 && banana_collision.intersect_rect?(state.player_2.solid)
      state.over = true
      if state.banana.owner == state.player_2
        state.winner = :player_1
      else
        state.winner = :player_2
      end
      state.player_1_score += 1
    end

    if state.over
      place_hole
      return
    end

    return if state.holes.any? do |h|
      h.sprite.scale_rect(0.8, 0.5, 0.5).intersect_rect? [state.banana.x, state.banana.y, 10, 10]
    end

    return unless state.banana.y < 0 || state.buildings.any? do |b|
      b.rect.intersect_rect? [state.banana.x, state.banana.y, 1, 1]
    end

    place_hole
  end

  def place_hole
    return unless state.banana

    state.holes << state.new_entity(:banana) do |b|
      b.sprite = [state.banana.x - 20, state.banana.y - 20, 40, 40, 'sprites/hole.png']
    end

    state.banana = nil
  end

  def process_inputs_main
    return if state.banana
    return if state.over

    if inputs.keyboard.key_down.enter
      input_execute_turn
    elsif inputs.keyboard.key_down.backspace
      state.as_hash[state.current_turn] ||= ""
      state.as_hash[state.current_turn]   = state.as_hash[state.current_turn][0..-2]
    elsif inputs.keyboard.key_down.char
      state.as_hash[state.current_turn] ||= ""
      state.as_hash[state.current_turn]  += inputs.keyboard.key_down.char
    end
  end

  def process_inputs_game_over
    return unless state.over
    return unless inputs.keyboard.key_down.truthy_keys.any?
    state.over = false
    outputs.static_solids.clear
    state.buildings.clear
    state.holes.clear
    state.stage_generated = false
    state.stage_rendered = false
    if state.first_strike == :player_1
      state.first_strike = :player_2
    else
      state.first_strike = :player_1
    end
  end

  def process_inputs
    process_inputs_main
    process_inputs_game_over
  end

  def input_execute_turn
    return if state.banana

    if state.current_turn == :player_1_angle && parse_or_clear!(:player_1_angle)
      state.current_turn = :player_1_velocity
    elsif state.current_turn == :player_1_velocity && parse_or_clear!(:player_1_velocity)
      state.current_turn = :player_2_angle
      state.banana =
        new_banana(state.player_1,
                   state.player_1.x + 25,
                   state.player_1.y + 60,
                   state.player_1_angle,
                   state.player_1_velocity)
    elsif state.current_turn == :player_2_angle && parse_or_clear!(:player_2_angle)
      state.current_turn = :player_2_velocity
    elsif state.current_turn == :player_2_velocity && parse_or_clear!(:player_2_velocity)
      state.current_turn = :player_1_angle
      state.banana =
        new_banana(state.player_2,
                   state.player_2.x + 25,
                   state.player_2.y + 60,
                   180 - state.player_2_angle,
                   state.player_2_velocity)
    end

    if state.banana
      state.player_1_angle = nil
      state.player_1_velocity = nil
      state.player_2_angle = nil
      state.player_2_velocity = nil
    end
  end

  def random_building_size
    [state.building_heights.sample, state.building_room_sizes.sample]
  end

  def int? v
    v.to_i.to_s == v.to_s
  end

  def random_building_color
    [[ 99,   0, 107],
     [ 35,  64, 124],
     [ 35, 136, 162],
     ].sample
  end

  def random_window_color
    [[ 88,  62, 104],
     [253, 224, 187]].sample
  end

  def windows_for_building starting_x, floors, rooms
    floors.-(1).combinations(rooms - 1).map do |floor, room|
      [starting_x +
       state.building_room_width.*(room) +
       state.building_room_spacing.*(room + 1),
       state.building_room_height.*(floor) +
       state.building_room_spacing.*(floor + 1),
       state.building_room_width,
       state.building_room_height,
       random_window_color]
    end
  end

  def building_prefab starting_x, floors, rooms
    state.new_entity(:building) do |b|
      b.x      = starting_x
      b.y      = 0
      b.w      = state.building_room_width.*(rooms) +
                 state.building_room_spacing.*(rooms + 1)
      b.h      = state.building_room_height.*(floors) +
                 state.building_room_spacing.*(floors + 1)
      b.right  = b.x + b.w
      b.rect   = [b.x, b.y, b.w, b.h]
      b.solids = [[b.x - 1, b.y, b.w + 2, b.h + 1, fancy_white],
                  [b.x, b.y, b.w, b.h, random_building_color],
                  windows_for_building(b.x, floors, rooms)]
    end
  end

  def parse_or_clear! game_prop
    if int? state.as_hash[game_prop]
      state.as_hash[game_prop] = state.as_hash[game_prop].to_i
      return true
    end

    state.as_hash[game_prop] = nil
    return false
  end

  def new_banana owner, x, y, angle, velocity
    state.new_entity(:banana) do |b|
      b.owner     = owner
      b.x         = x
      b.y         = y
      b.angle     = angle % 360
      b.velocity  = velocity / 5
      b.dx        = b.angle.vector_x(b.velocity)
      b.dy        = b.angle.vector_y(b.velocity)
    end
  end

  def fancy_white
    [253, 252, 253]
  end
end

$you_so_basic_gorillas = YouSoBasicGorillas.new

def tick args
  $you_so_basic_gorillas.outputs = args.outputs
  $you_so_basic_gorillas.grid    = args.grid
  $you_so_basic_gorillas.state    = args.state
  $you_so_basic_gorillas.inputs  = args.inputs
  $you_so_basic_gorillas.tick
end

    Shadows - main.rb link

    # ./samples/99_genre_platformer/shadows/app/main.rb
# demo gameplay here: https://youtu.be/wQknjYk_-dE
# this is the core game class. the game is
# pretty small so this is the only class that was created
class Game
  # attr_gtk is a ruby class macro (mixin) that
  # adds the .args, .inputs, .outputs, and .state
  # properties to a class
  attr_gtk

  # this is the main tick method that
  # will be called every frame
  # the tick method is your standard game loop.
  # ie initialize game state, process input,
  #    perform simulation calculations, then render
  def tick
    defaults
    input
    calc
    render
  end

  # defaults method re-initializes the game to its
  # starting point if
  # 1. it hasn't already been initialized (state.clock is nil)
  # 2. or reinitializes the game if the player died (game_over)
  def defaults
    new_game if !state.clock || state.game_over == true
  end

  # this is where inputs are processed
  # we process inputs for the player via input_entity
  # and then process inputs for each enemy using the same
  # input_entity function
  def input
    input_entity player,
                 find_input_timeline(at: player.clock, key: :left_right),
                 find_input_timeline(at: player.clock, key: :space),
                 find_input_timeline(at: player.clock, key: :down)

    # an enemy could still be spawing
    shadows.find_all { |shadow| entity_active? shadow }
           .each do |shadow|
             input_entity shadow,
                          find_input_timeline(at: shadow.clock, key: :left_right),
                          find_input_timeline(at: shadow.clock, key: :space),
                          find_input_timeline(at: shadow.clock, key: :down)
             end
  end

  # this is the input_entity function that handles
  # the movement of the player (and the enemies)
  # it's essentially your state machine for player
  # movement
  def input_entity entity, left_right, jump, fall_through
    # guard clause that ignores input processing if
    # the entity is still spawning
    return if !entity_active? entity

    # increment the dx of the entity by the magnitude of
    # the left_right input value
    entity.dx += left_right

    # if the left_right input is zero...
    if left_right == 0
      # if the entity was originally running, then
      # set their "action" to standing
      # entity_set_action! updates the current action
      # of the entity and takes note of the frame that
      # the action occured on
      if (entity.action == :running)
        entity_set_action! entity, :standing
      end
    elsif entity.left_right != left_right && (entity_on_platform? entity)
      # if the entity is on a platform, and their current
      # left right value is different, mark them as running
      # this is done because we want to reset the run animation
      # if they changed directions
      entity_set_action! entity, :running
    end

    # capture the left_right input so that it can be
    # consulted on the next frame
    entity.left_right = left_right

    # capture the direction the player is facing
    # (this is used to determine the horizontal flip of the
    # sprite
    entity.orientation = if left_right == -1
                           :left
                         elsif left_right == 1
                           :right
                         else
                           entity.orientation
                         end

    # if the fall_through (down) input was requested,
    # and if they are on a platform...
    if fall_through && (entity_on_platform? entity)
      entity.jumped_at      = 0
      # set their jump_down value (falling through a platform)
      entity.jumped_down_at = entity.clock
      # and increment the number of times they jumped
      # (entities get three jumps before needing to touch the ground again)
      entity.jump_count    += 1
    end

    # if the jump input was requested
    # and if they haven't reached their jump limit
    if jump && entity.jump_count < 3
      # update the player's current action to the
      # corresponding jump number (used for rendering
      # the different jump animations)
      if entity.jump_count == 0
        entity_set_action! entity, :first_jump
      elsif entity.jump_count == 1
        entity_set_action! entity, :midair_jump
      elsif entity.jump_count == 2
        entity_set_action! entity, :midair_jump
      end

      # set the entity's dy value and take note
      # of when jump occured (also increment jump
      # count/eat one of their jumps)
      entity.dy             = entity.jump_power
      entity.jumped_at      = entity.clock
      entity.jumped_down_at = 0
      entity.jump_count    += 1
    end
  end

  # after inputs have been processed, we then
  # determine game over states, collision, win states
  # etc
  def calc
    # calculate the new values of the light meter
    # (if the light meter hits zero, it's game over)
    calc_light_meter

    # capture the actions that were taken this turn so
    # that they can be "replayed" for the enemies on future
    # ticks of the simulation
    calc_action_history

    # calculate collisions for the player
    calc_entity player

    # calculate collisions for the enemies
    calc_shadows

    # spawn a new light crystal
    calc_light_crystal

    # process "fire and forget" render queues
    # (eg particles and death animations)
    calc_render_queues

    # determine game over
    calc_game_over

    # increment the internal clocks for all entities
    # this internal clock is used to determine how
    # a player's past input is replayed. it's also
    # used to determine what animation frame the entity
    # should be performing when idle, running, and jumping
    calc_clock
  end

  # ease the light meters value up or down
  # every time the player captures a light crystal
  # the "target" light meter value is increased and
  # slowly spills over to the final light meter value
  # which is used to determine game over
  def calc_light_meter
    state.light_meter -= 1
    d = state.light_meter_queue * 0.1
    state.light_meter += d
    state.light_meter_queue -= d
  end

  def calc_action_history
    # keep track of the inputs the player has performed over time
    # as the inputs change for the player, mark the point in time
    # the specific input changed, and when the change occured.
    # when enemies replay the player's actions, this history (along
    # with the enemy's interal clock) is consulted to determine
    # what action should be performed

    # the three possible input events are captured and marked
    # within the input timeline if/when the value changes

    # left right input events
    state.curr_left_right     = inputs.left_right
    if state.prev_left_right != state.curr_left_right
      state.input_timeline.unshift({ at: state.clock, k: :left_right, v: state.curr_left_right })
    end
    state.prev_left_right = state.curr_left_right

    # jump input events
    state.curr_space     = inputs.keyboard.key_down.space    ||
                           inputs.controller_one.key_down.a  ||
                           inputs.keyboard.key_down.up       ||
                           inputs.controller_one.key_down.b
    if state.prev_space != state.curr_space
      state.input_timeline.unshift({ at: state.clock, k: :space, v: state.curr_space })
    end
    state.prev_space = state.curr_space

    # jump down (fall through platform)
    state.curr_down     = inputs.keyboard.down || inputs.controller_one.down
    if state.prev_down != state.curr_down
      state.input_timeline.unshift({ at: state.clock, k: :down, v: state.curr_down })
    end
    state.prev_down = state.curr_down
  end

  def calc_entity entity
    # process entity collision/simulation
    calc_entity_rect entity

    # return if the entity is still spawning
    return if !entity_active? entity

    # calc collisions
    calc_entity_collision entity

    # update the state machine of the entity based on the
    # collision results
    calc_entity_action entity

    # calc actions the entity should take based on
    # input timeline
    calc_entity_movement entity
  end

  def calc_entity_rect entity
    # this function calculates the entity's new
    # collision rect, render rect, hurt box, etc
    entity.render_rect = { x: entity.x, y: entity.y, w: entity.w, h: entity.h }
    entity.rect = entity.render_rect.merge x: entity.render_rect.x + entity.render_rect.w * 0.33,
                                           w: entity.render_rect.w * 0.33
    entity.next_rect = entity.rect.merge x: entity.x + entity.dx,
                                         y: entity.y + entity.dy
    entity.prev_rect = entity.rect.merge x: entity.x - entity.dx,
                                         y: entity.y - entity.dy
    orientation_shift = 0
    if entity.orientation == :right
      orientation_shift = entity.rect.w.half
    end
    entity.hurt_rect  = entity.rect.merge y: entity.rect.y + entity.h * 0.33,
                                          x: entity.rect.x - entity.rect.w.half + orientation_shift,
                                          h: entity.rect.h * 0.33
  end

  def calc_entity_collision entity
    # run of the mill AABB collision
    calc_entity_below entity
    calc_entity_left entity
    calc_entity_right entity
  end

  def calc_entity_below entity
    # exit ground collision detection if they aren't falling
    return unless entity.dy < 0
    tiles_below = find_tiles { |t| t.rect.top <= entity.prev_rect.y }
    collision = find_collision tiles_below, (entity.rect.merge y: entity.next_rect.y)

    # exit ground collision detection if no ground was found
    return unless collision

    # determine if the entity is allowed to fall through the platform
    # (you can only fall through a platform if you've been standing on it for 8 frames)
    can_drop = true
    if entity.last_standing_at && (entity.clock - entity.last_standing_at) < 8
      can_drop = false
    end

    # if the entity is allowed to fall through the platform,
    # and the entity requested the action, then clip them through the platform
    if can_drop && entity.jumped_down_at.elapsed_time(entity.clock) < 10 && !collision.impassable
      if (entity_on_platform? entity) && can_drop
        entity.dy = -1
      end

      entity.jump_count = 1
    else
      entity.y  = collision.rect.y + collision.rect.h
      entity.dy = 0
      entity.jump_count = 0
    end
  end

  def calc_entity_left entity
    # collision detection left side of screen
    return unless entity.dx < 0
    return if entity.next_rect.x > 8 - 32
    entity.x  = 8 - 32
    entity.dx = 0
  end

  def calc_entity_right entity
    # collision detection right side of screen
    return unless entity.dx > 0
    return if (entity.next_rect.x + entity.rect.w) < (1280 - 8 - 32)
    entity.x  = (1280 - 8 - entity.rect.w - 32)
    entity.dx = 0
  end

  def calc_entity_action entity
    # update the state machine of the entity
    # based on where they ended up after physics calculations
    if entity.dy < 0
      # mark the entity as falling after the jump animation frames
      # have been processed
      if entity.action == :midair_jump
        if entity_action_complete? entity, state.midair_jump_duration
          entity_set_action! entity, :falling
        end
      else
        entity_set_action! entity, :falling
      end
    elsif entity.dy == 0 && !(entity_on_platform? entity)
      # if the entity's dy is zero, determine if they should
      # be marked as standing or running
      if entity.left_right == 0
        entity_set_action! entity, :standing
      else
        entity_set_action! entity, :running
      end
    end
  end

  def calc_entity_movement entity
    # increment x and y positions of the entity
    # based on dy and dx
    calc_entity_dy entity
    calc_entity_dx entity
  end

  def calc_entity_dx entity
    # horizontal movement application and friction
    entity.dx  = entity.dx.clamp(-5,  5)
    entity.dx *= 0.9
    entity.x  += entity.dx
  end

  def calc_entity_dy entity
    # vertical movement application and gravity
    entity.y  += entity.dy
    entity.dy += state.gravity
    entity.dy += entity.dy * state.drag ** 2 * -1
  end

  def calc_shadows
    # every 5 seconds, add a new shadow enemy/increase difficult
    add_shadow! if state.clock.zmod?(300)

    # for each shadow, perform a simulation calculation
    shadows.each do |shadow|
      calc_entity shadow

      # decrement the spawn countdown which is used to determine if
      # the enemy is finally active
      shadow.spawn_countdown -= 1 if shadow.spawn_countdown > 0
    end
  end

  def calc_light_crystal
    # determine if the player has intersected with a light crystal
    light_rect = state.light_crystal
    if player.hurt_rect.intersect_rect? light_rect
      # if they have then queue up the partical animation of the
      # light crystal being collected
      state.jitter_fade_out_render_queue << { x:    state.light_crystal.x,
                                              y:    state.light_crystal.y,
                                              w:    state.light_crystal.w,
                                              h:    state.light_crystal.h,
                                              a:    255,
                                              path: 'sprites/light.png' }

      # increment the light meter target value
      state.light_meter_queue += 600

      # spawn a new light cristal for the player to try to get
      state.light_crystal = new_light_crystal
    end
  end

  def calc_render_queues
    # render all the entries in the "fire and forget" render queues
    state.jitter_fade_out_render_queue.each do |s|
      new_w = s.w * 1.02 ** 5
      ds = new_w - s.w
      s.w = new_w
      s.h = new_w
      s.x -= ds.half
      s.y -= ds.half
      s.a = s.a * 0.97 ** 5
    end

    state.jitter_fade_out_render_queue.reject! { |s| s.a <= 1 }

    state.game_over_render_queue.each { |s| s.a = s.a * 0.95 }
    state.game_over_render_queue.reject! { |s| s.a <= 1 }
  end

  def calc_game_over
    # calcuate game over
    state.game_over = false

    # it's game over if the player intersects with any of the enemies
    state.game_over ||= shadows.find_all { |s| s.spawn_countdown <= 0 }
                               .any? { |s| s.hurt_rect.intersect_rect? player.hurt_rect }

    # it's game over if the light_meter hits 0
    state.game_over ||= state.light_meter <= 1

    # debug to reset the game/prematurely
    if inputs.keyboard.key_down.r
      state.you_win = false
      state.game_over = true
    end

    # update game over states and win/loss
    if state.game_over
      state.you_win = false
      state.game_over = true
    end

    if state.light_meter >= 6000
      state.you_win = true
      state.game_over = true
    end

    # if it's a game over, fade out all current entities in play
    if state.game_over
      state.game_over_render_queue.concat shadows.map { |s| s.sprite.merge(a: 255) }
      state.game_over_render_queue << player.sprite.merge(a: 255)
      state.game_over_render_queue << state.light_crystal.merge(a: 255, path: 'sprites/light.png', b: 128)
    end
  end

  def calc_clock
    return if state.game_over
    state.clock += 1
    player.clock += 1
    shadows.each { |s| s.clock += 1 if entity_active? s }
  end

  def render
    # render the game
    render_stage
    render_light_meter
    render_instructions
    render_render_queues
    render_light_meter_warning
    render_light_crystal
    render_entities
  end

  def render_stage
    # the stage is a simple background
    outputs.background_color = [255, 255, 255]
    outputs.sprites << { x: 0,
                         y: 0,
                         w: 1280,
                         h: 720,
                         path: "sprites/stage.png",
                         a: 200 }
  end

  def render_light_meter
    # the light meter sprite is rendered across the top
    # how much of the light meter is light vs dark is based off
    # of what the current light meter value is (which increases
    # when a crystal is collected and decreses a little bit every
    # frame
    meter_perc = state.light_meter.fdiv(6000) + (0.002 * rand)
    light_w = (1280 * meter_perc).round
    dark_w  = 1280 - light_w

    # once the light and dark partitions have been computed
    # render the meter sprite and clip its width (source_w)
    outputs.sprites << { x: 0,
                         y: 64.from_top,
                         w: light_w,
                         source_x: 0,
                         source_y: 0,
                         source_w: light_w,
                         source_h: 128,
                         h: 64,
                         path: 'sprites/meter-light.png' }

    outputs.sprites << { x: 1280 * meter_perc,
                         y: 64.from_top,
                         w: dark_w,
                         source_x: light_w,
                         source_y: 0,
                         source_w: dark_w,
                         source_h: 128,
                         h: 64,
                         path: 'sprites/meter-dark.png' }
  end

  def render_instructions
    outputs.labels << { x: 640,
                        y: 40,
                        text: '[left/right] to move, [up/space] to jump, [down] to drop through platform',
                        alignment_enum: 1 }

    if state.you_win
      outputs.labels << { x: 640,
                          y: 40.from_top,
                          text: 'You win!',
                          size_enum: -1,
                          alignment_enum: 1 }
    end
  end

  def render_render_queues
    outputs.sprites << state.jitter_fade_out_render_queue
    outputs.sprites << state.game_over_render_queue
  end

  def render_light_meter_warning
    return if state.light_meter >= 255

    # the screen starts to dim if they are close to having
    # a game over because of a depleated light meter
    outputs.primitives << { x: 0,
                            y: 0,
                            w: 1280,
                            h: 720,
                            a: 255 - state.light_meter,
                            path: :pixel,
                            r: 0,
                            g: 0,
                            b: 0 }

    outputs.primitives << { x: state.light_crystal.x - 32,
                            y: state.light_crystal.y - 32,
                            w: 128,
                            h: 128,
                            a: 255 - state.light_meter,
                            path: 'sprites/spotlight.png' }
  end

  def render_light_crystal
    jitter_sprite = { x: state.light_crystal.x + 5 * rand,
                      y: state.light_crystal.y + 5 * rand,
                      w: state.light_crystal.w + 5 * rand,
                      h: state.light_crystal.h + 5 * rand,
                      path: 'sprites/light.png' }
    outputs.primitives << jitter_sprite
  end

  def render_entities
    render_entity player, r: 0, g: 0, b: 0
    shadows.each { |shadow| render_entity shadow, g: 0, b: 0 }
  end

  def render_entity entity, r: 255, g: 255, b: 255;
    # this is essentially the entity "prefab"
    # the current action of the entity is consulted to
    # determine what sprite should be rendered
    # the action_at time is consulted to determine which frame
    # of the sprite animation should be presented
    a = 255

    entity.sprite = nil

    if entity.activate_at
      activation_elapsed_time = state.clock - entity.activate_at
      if entity.activate_at > state.clock
        entity.sprite = { x: entity.initial_x + 5 * rand,
                          y: entity.initial_y + 5 * rand,
                          w: 64 + 5 * rand,
                          h: 64 + 5 * rand,
                          path: "sprites/light.png",
                          g: 0, b: 0,
                          a: a }

        outputs.sprites << entity.sprite
        return
      elsif !entity.activated
        entity.activated = true
        state.jitter_fade_out_render_queue << { x: entity.initial_x + 5 * rand,
                                                y: entity.initial_y + 5 * rand,
                                                w: 86 + 5 * rand, h: 86 + 5 * rand,
                                                path: "sprites/light.png",
                                                g: 0, b: 0, a: 255 }
      end
    end

    # this is the render outputs for an entities action state machine
    if entity.action == :standing
      path = "sprites/player/stand.png"
    elsif entity.action == :running
      sprint_index = entity.action_at
                           .frame_index count: 4,
                                        hold_for: 8,
                                        repeat: true,
                                        tick_count_override: entity.clock
      path = "sprites/player/run-#{sprint_index}.png"
    elsif entity.action == :first_jump
      sprint_index = entity.action_at
                           .frame_index count: 2,
                                        hold_for: 8,
                                        repeat: false,
                                        tick_count_override: entity.clock
      path = "sprites/player/jump-#{sprint_index || 1}.png"
    elsif entity.action == :midair_jump
      sprint_index = entity.action_at
                           .frame_index count: state.midair_jump_frame_count,
                                        hold_for: state.midair_jump_hold_for,
                                        repeat: false,
                                        tick_count_override: entity.clock
      path = "sprites/player/midair-jump-#{sprint_index || 8}.png"
    elsif entity.action == :falling
      path = "sprites/player/falling.png"
    end

    flip_horizontally = true if entity.orientation == :left
    entity.sprite = entity.render_rect.merge path: path,
                                             a: a,
                                             r: r,
                                             g: g,
                                             b: b,
                                             flip_horizontally: flip_horizontally
    outputs.sprites << entity.sprite
  end

  def new_game
    state.clock                   = 0
    state.game_over               = false
    state.gravity                 = -0.4
    state.drag                    = 0.15

    state.activation_time         = 90
    state.light_meter             = 600
    state.light_meter_queue       = 0

    state.midair_jump_frame_count = 9
    state.midair_jump_hold_for    = 6
    state.midair_jump_duration    = state.midair_jump_frame_count * state.midair_jump_hold_for

    # hard coded collision tiles
    state.tiles                   = [
      { impassable: true, x: 0, y: 0, w: 1280, h: 8, path: :pixel, r: 0, g: 0, b: 0 },
      { impassable: true, x: 0, y: 0, w: 8, h: 1500, path: :pixel, r: 0, g: 0, b: 0 },
      { impassable: true, x: 1280 - 8, y: 0, w: 8, h: 1500, path: :pixel, r: 0, g: 0, b: 0 },

      { x: 80 + 320 + 80,            y: 128, w: 320, h: 8, path: :pixel, r: 0, g: 0, b: 0 },
      { x: 80 + 320 + 80 + 320 + 80, y: 192, w: 320, h: 8, path: :pixel, r: 0, g: 0, b: 0 },

      { x: 160,                      y: 320, w: 400, h: 8, path: :pixel, r: 0, g: 0, b: 0 },
      { x: 160 + 400 + 160,          y: 400, w: 400, h: 8, path: :pixel, r: 0, g: 0, b: 0 },

      { x: 320,                      y: 600, w: 320, h: 8, path: :pixel, r: 0, g: 0, b: 0 },

      { x: 8, y: 500, w: 100, h: 8, path: :pixel, r: 0, g: 0, b: 0 },

      { x: 8, y: 60, w: 100, h: 8, path: :pixel, r: 0, g: 0, b: 0 },
    ]

    state.player                = new_entity
    state.player.jump_count     = 1
    state.player.jumped_at      = state.player.clock
    state.player.jumped_down_at = 0

    state.shadows   = []

    state.input_timeline = [
      { at: 0, k: :left_right, v: inputs.left_right },
      { at: 0, k: :space,      v: false },
      { at: 0, k: :down,       v: false },
    ]

    state.jitter_fade_out_render_queue   = []
    state.game_over_render_queue       ||= []

    state.light_crystal = new_light_crystal
  end

  def new_light_crystal
    r = { x: 124 + rand(1000), y: 135 + rand(500), w: 64, h: 64 }
    return new_light_crystal if tiles.any? { |t| t.intersect_rect? r }
    return new_light_crystal if (player.x - r.x).abs < 200
    r
  end

  def entity_active? entity
    return true unless entity.activate_at
    return entity.activate_at <= state.clock
  end

  def add_shadow!
    s = new_entity(from_entity: player)
    s.activate_at = state.clock + state.activation_time * (shadows.length + 1)
    s.spawn_countdown = state.activation_time
    shadows << s
  end

  def find_input_timeline at:, key:;
    state.input_timeline.find { |t| t.at <= at && t.k == key }.v
  end

  def new_entity from_entity: nil
    # these are all the properties of an entity
    # an optional from_entity can be passed in
    # for "cloning" an entity/setting an entities
    # starting state
    pe = state.new_entity(:body)
    pe.w                  = 96
    pe.h                  = 96
    pe.jump_power         = 12
    pe.y                  = 500
    pe.x                  = 640 - 8
    pe.initial_x          = pe.x
    pe.initial_y          = pe.y
    pe.dy                 = 0
    pe.dx                 = 0
    pe.jumped_down_at     = 0
    pe.jumped_at          = 0
    pe.jump_count         = 0
    pe.clock              = state.clock
    pe.orientation        = :right
    pe.action             = :falling
    pe.action_at          = state.clock
    pe.left_right         = 0
    if from_entity
      pe.w              = from_entity.w
      pe.h              = from_entity.h
      pe.jump_power     = from_entity.jump_power
      pe.x              = from_entity.x
      pe.y              = from_entity.y
      pe.initial_x      = from_entity.x
      pe.initial_y      = from_entity.y
      pe.dy             = from_entity.dy
      pe.dx             = from_entity.dx
      pe.jumped_down_at = from_entity.jumped_down_at
      pe.jumped_at      = from_entity.jumped_at
      pe.orientation    = from_entity.orientation
      pe.action         = from_entity.action
      pe.action_at      = from_entity.action_at
      pe.jump_count     = from_entity.jump_count
      pe.left_right     = from_entity.left_right
    end
    pe
  end

  def entity_on_platform? entity
    entity.action == :standing || entity.action == :running
  end

  def entity_action_complete? entity, action_duration
    entity.action_at.elapsed_time(entity.clock) + 1 >= action_duration
  end

  def entity_set_action! entity, action
    entity.action = action
    entity.action_at = entity.clock
    entity.last_standing_at = entity.clock if action == :standing
  end

  def player
    state.player
  end

  def shadows
    state.shadows
  end

  def tiles
    state.tiles
  end

  def find_tiles &block
    tiles.find_all(&block)
  end

  def find_collision tiles, target
    tiles.find { |t| t.rect.intersect_rect? target }
  end
end

def boot args
  # initialize the game on boot
  $game = Game.new
end

def tick args
  # tick the game class after setting .args
  # (which is provided by the engine)
  $game.args = args
  $game.tick
end

# debug function for resetting the game if requested
def reset args
  $game = Game.new
end

    The Little Probe - main.rb link

    # ./samples/99_genre_platformer/the_little_probe/app/main.rb
class FallingCircle
  attr_gtk

  def tick
    fiddle
    defaults
    render
    input
    calc
  end

  def fiddle
    state.gravity     = -0.02
    circle.radius     = 15
    circle.elasticity = 0.4
    camera.follow_speed = 0.4 * 0.4
  end

  def render
    render_stage_editor
    render_debug
    render_game
  end

  def defaults
    if state.tick_count == 0
      outputs.sounds << "sounds/bg.ogg"
    end

    state.storyline ||= [
      { text: "<- -> to aim, hold space to charge",                            distance_gate: 0 },
      { text: "the little probe - by @amirrajan, made with DragonRuby Game Toolkit", distance_gate: 0 },
      { text: "mission control, this is sasha. landing on europa successful.", distance_gate: 0 },
      { text: "operation \"find earth 2.0\", initiated at 8-29-2036 14:00.",   distance_gate: 0 },
      { text: "jupiter's sure is beautiful...",   distance_gate: 4000 },
      { text: "hmm, it seems there's some kind of anomoly in the sky",   distance_gate: 7000 },
      { text: "dancing lights, i'll call them whisps.",   distance_gate: 8000 },
      { text: "#todo... look i ran out of time -_-",   distance_gate: 9000 },
      { text: "there's never enough time",   distance_gate: 9000 },
      { text: "the game jam was fun though ^_^",   distance_gate: 10000 },
    ]

    load_level force: args.state.tick_count == 0
    state.line_mode            ||= :terrain

    state.sound_index          ||= 1
    circle.potential_lift      ||= 0
    circle.angle               ||= 90
    circle.check_point_at      ||= -1000
    circle.game_over_at        ||= -1000
    circle.x                   ||= -485
    circle.y                   ||= 12226
    circle.check_point_x       ||= circle.x
    circle.check_point_y       ||= circle.y
    circle.dy                  ||= 0
    circle.dx                  ||= 0
    circle.previous_dy         ||= 0
    circle.previous_dx         ||= 0
    circle.angle               ||= 0
    circle.after_images        ||= []
    circle.terrains_to_monitor ||= {}
    circle.impact_history      ||= []

    camera.x                   ||= 0
    camera.y                   ||= 0
    camera.target_x            ||= 0
    camera.target_y            ||= 0
    state.snaps                ||= { }
    state.snap_number            = 10

    args.state.storyline_x ||= -1000
    args.state.storyline_y ||= -1000
  end

  def render_game
    outputs.background_color = [0, 0, 0]
    outputs.sprites << [-circle.x + 1100,
                        -circle.y - 100,
                        2416 * 4,
                        3574 * 4,
                        'sprites/jupiter.png']
    outputs.sprites << [-circle.x,
                        -circle.y,
                        2416 * 4,
                        3574 * 4,
                        'sprites/level.png']
    outputs.sprites << state.whisp_queue
    render_aiming_retical
    render_circle
    render_notification
  end

  def render_notification
    toast_length = 500
    if circle.game_over_at.elapsed_time < toast_length
      label_text = "..."
    elsif circle.check_point_at.elapsed_time > toast_length
      args.state.current_storyline = nil
      return
    end
    if circle.check_point_at &&
       circle.check_point_at.elapsed_time == 1 &&
       !args.state.current_storyline
       if args.state.storyline.length > 0 && args.state.distance_traveled > args.state.storyline[0][:distance_gate]
         args.state.current_storyline = args.state.storyline.shift[:text]
         args.state.distance_traveled ||= 0
         args.state.storyline_x = circle.x
         args.state.storyline_y = circle.y
       end
      return unless args.state.current_storyline
    end
    label_text = args.state.current_storyline
    return unless label_text
    x = circle.x + camera.x
    y = circle.y + camera.y - 40
    w = 900
    h = 30
    outputs.primitives << [x - w.idiv(2), y - h, w, h, 255, 255, 255, 255].solid
    outputs.primitives << [x - w.idiv(2), y - h, w, h, 0, 0, 0, 255].border
    outputs.labels << [x, y - 4, label_text, 1, 1, 0, 0, 0, 255]
  end

  def render_aiming_retical
    outputs.sprites << [state.camera.x + circle.x + circle.angle.vector_x(circle.potential_lift * 10) - 5,
                        state.camera.y + circle.y + circle.angle.vector_y(circle.potential_lift * 10) - 5,
                        10, 10, 'sprites/circle-orange.png']
    outputs.sprites << [state.camera.x + circle.x + circle.angle.vector_x(circle.radius * 3) - 5,
                        state.camera.y + circle.y + circle.angle.vector_y(circle.radius * 3) - 5,
                        10, 10, 'sprites/circle-orange.png', 0, 128]
    if rand > 0.9
      outputs.sprites << [state.camera.x + circle.x + circle.angle.vector_x(circle.radius * 3) - 5,
                          state.camera.y + circle.y + circle.angle.vector_y(circle.radius * 3) - 5,
                          10, 10, 'sprites/circle-white.png', 0, 128]
    end
  end

  def render_circle
    outputs.sprites << circle.after_images.map do |ai|
      ai.merge(x: ai.x + state.camera.x - circle.radius,
               y: ai.y + state.camera.y - circle.radius,
               w: circle.radius * 2,
               h: circle.radius * 2,
               path: 'sprites/circle-white.png')
    end

    outputs.sprites << [(circle.x - circle.radius) + state.camera.x,
                        (circle.y - circle.radius) + state.camera.y,
                        circle.radius * 2,
                        circle.radius * 2,
                        'sprites/probe.png']
  end

  def render_debug
    return unless state.debug_mode

    outputs.labels << [10, 30, state.line_mode, 0, 0, 0, 0, 0]
    outputs.labels << [12, 32, state.line_mode, 0, 0, 255, 255, 255]

    args.outputs.lines << trajectory(circle).line.to_hash.tap do |h|
      h[:x] += state.camera.x
      h[:y] += state.camera.y
      h[:x2] += state.camera.x
      h[:y2] += state.camera.y
    end

    outputs.primitives << state.terrain.find_all do |t|
      circle.x.between?(t.x - 640, t.x2 + 640) || circle.y.between?(t.y - 360, t.y2 + 360)
    end.map do |t|
      [
        t.line.associate(r: 0, g: 255, b: 0) do |h|
          h.x  += state.camera.x
          h.y  += state.camera.y
          h.x2 += state.camera.x
          h.y2 += state.camera.y
          if circle.rect.intersect_rect? t[:rect]
            h[:r] = 255
            h[:g] = 0
          end
          h
        end,
        t[:rect].border.associate(r: 255, g: 0, b: 0) do |h|
          h.x += state.camera.x
          h.y += state.camera.y
          h.b = 255 if line_near_rect? circle.rect, t
          h
        end
      ]
    end

    outputs.primitives << state.lava.find_all do |t|
      circle.x.between?(t.x - 640, t.x2 + 640) || circle.y.between?(t.y - 360, t.y2 + 360)
    end.map do |t|
      [
        t.line.associate(r: 0, g: 0, b: 255) do |h|
          h.x  += state.camera.x
          h.y  += state.camera.y
          h.x2 += state.camera.x
          h.y2 += state.camera.y
          if circle.rect.intersect_rect? t[:rect]
            h[:r] = 255
            h[:b] = 0
          end
          h
        end,
        t[:rect].border.associate(r: 255, g: 0, b: 0) do |h|
          h.x += state.camera.x
          h.y += state.camera.y
          h.b = 255 if line_near_rect? circle.rect, t
          h
        end
      ]
    end

    if state.god_mode
      border = circle.rect.merge(x: circle.rect.x + state.camera.x,
                                 y: circle.rect.y + state.camera.y,
                                 g: 255)
    else
      border = circle.rect.merge(x: circle.rect.x + state.camera.x,
                                 y: circle.rect.y + state.camera.y,
                                 b: 255)
    end

    outputs.borders << border

    overlapping ||= {}

    circle.impact_history.each do |h|
      label_mod = 300
      x = (h[:body][:x].-(150).idiv(label_mod)) * label_mod + camera.x
      y = (h[:body][:y].+(150).idiv(label_mod)) * label_mod + camera.y
      10.times do
        if overlapping[x] && overlapping[x][y]
          y -= 52
        else
          break
        end
      end

      overlapping[x] ||= {}
      overlapping[x][y] ||= true
      outputs.primitives << [x, y - 25, 300, 50, 0, 0, 0, 128].solid
      outputs.labels << [x + 10, y + 24, "dy: %.2f" % h[:body][:new_dy], -2, 0, 255, 255, 255]
      outputs.labels << [x + 10, y +  9, "dx: %.2f" % h[:body][:new_dx], -2, 0, 255, 255, 255]
      outputs.labels << [x + 10, y -  5, " ?: #{h[:body][:new_reason]}", -2, 0, 255, 255, 255]

      outputs.labels << [x + 100, y + 24, "angle: %.2f" % h[:impact][:angle], -2, 0, 255, 255, 255]
      outputs.labels << [x + 100, y + 9, "m(l): %.2f" % h[:terrain][:slope], -2, 0, 255, 255, 255]
      outputs.labels << [x + 100, y - 5, "m(c): %.2f" % h[:body][:slope], -2, 0, 255, 255, 255]

      outputs.labels << [x + 200, y + 24, "ray: #{h[:impact][:ray]}", -2, 0, 255, 255, 255]
      outputs.labels << [x + 200, y +  9, "nxt: #{h[:impact][:ray_next]}", -2, 0, 255, 255, 255]
      outputs.labels << [x + 200, y -  5, "typ: #{h[:impact][:type]}", -2, 0, 255, 255, 255]
    end

    if circle.floor
      outputs.labels << [circle.x + camera.x + 30, circle.y + camera.y + 100, "point: #{circle.floor_point.slice(:x, :y).values}", -2, 0]
      outputs.labels << [circle.x + camera.x + 31, circle.y + camera.y + 101, "point: #{circle.floor_point.slice(:x, :y).values}", -2, 0, 255, 255, 255]
      outputs.labels << [circle.x + camera.x + 30, circle.y + camera.y +  85, "circle: #{circle.as_hash.slice(:x, :y).values}", -2, 0]
      outputs.labels << [circle.x + camera.x + 31, circle.y + camera.y +  86, "circle: #{circle.as_hash.slice(:x, :y).values}", -2, 0, 255, 255, 255]
      outputs.labels << [circle.x + camera.x + 30, circle.y + camera.y +  70, "rel: #{circle.floor_relative_x} #{circle.floor_relative_y}", -2, 0]
      outputs.labels << [circle.x + camera.x + 31, circle.y + camera.y +  71, "rel: #{circle.floor_relative_x} #{circle.floor_relative_y}", -2, 0, 255, 255, 255]
    end
  end

  def render_stage_editor
    return unless state.god_mode
    return unless state.point_one
    args.lines << [state.point_one, inputs.mouse.point, 0, 255, 255]
  end

  def trajectory body
    [body.x + body.dx,
     body.y + body.dy,
     body.x + body.dx * 1000,
     body.y + body.dy * 1000,
     0, 255, 255]
  end

  def lengthen_line line, num
    line = normalize_line(line)
    slope = geometry.line_slope(line, replace_infinity: 10).abs
    if slope < 2
      [line.x - num, line.y, line.x2 + num, line.y2].line.to_hash
    else
      [line.x, line.y, line.x2, line.y2].line.to_hash
    end
  end

  def normalize_line line
    if line.x > line.x2
      x  = line.x2
      y  = line.y2
      x2 = line.x
      y2 = line.y
    else
      x  = line.x
      y  = line.y
      x2 = line.x2
      y2 = line.y2
    end
    [x, y, x2, y2]
  end

  def rect_for_line line
    if line.x > line.x2
      x  = line.x2
      y  = line.y2
      x2 = line.x
      y2 = line.y
    else
      x  = line.x
      y  = line.y
      x2 = line.x2
      y2 = line.y2
    end

    w = x2 - x
    h = y2 - y

    if h < 0
      y += h
      h = h.abs
    end

    if w < circle.radius
      x -= circle.radius
      w = circle.radius * 2
    end

    if h < circle.radius
      y -= circle.radius
      h = circle.radius * 2
    end

    { x: x, y: y, w: w, h: h }
  end

  def snap_to_grid x, y, snaps
    snap_number = 10
    x = x.to_i
    y = y.to_i

    x_floor = x.idiv(snap_number) * snap_number
    x_mod   = x % snap_number
    x_ceil  = (x.idiv(snap_number) + 1) * snap_number

    y_floor = y.idiv(snap_number) * snap_number
    y_mod   = y % snap_number
    y_ceil  = (y.idiv(snap_number) + 1) * snap_number

    if snaps[x_floor]
      x_result = x_floor
    elsif snaps[x_ceil]
      x_result = x_ceil
    elsif x_mod < snap_number.idiv(2)
      x_result = x_floor
    else
      x_result = x_ceil
    end

    snaps[x_result] ||= {}

    if snaps[x_result][y_floor]
      y_result = y_floor
    elsif snaps[x_result][y_ceil]
      y_result = y_ceil
    elsif y_mod < snap_number.idiv(2)
      y_result = y_floor
    else
      y_result = y_ceil
    end

    snaps[x_result][y_result] = true
    return [x_result, y_result]

  end

  def snap_line line
    x, y, x2, y2 = line
  end

  def string_to_line s
    x, y, x2, y2 = s.split(',').map(&:to_f)

    if x > x2
      x2, x = x, x2
      y2, y = y, y2
    end

    x, y = snap_to_grid x, y, state.snaps
    x2, y2 = snap_to_grid x2, y2, state.snaps
    [x, y, x2, y2].line.to_hash
  end

  def load_lines file
    return unless state.snaps
    data = gtk.read_file(file) || ""
    data.each_line
        .reject { |l| l.strip.length == 0 }
        .map { |l| string_to_line l }
        .map { |h| h.merge(rect: rect_for_line(h))  }
  end

  def load_terrain
    load_lines 'data/level.txt'
  end

  def load_lava
    load_lines 'data/level_lava.txt'
  end

  def load_level force: false
    if force
      state.snaps = {}
      state.terrain = load_terrain
      state.lava = load_lava
    else
      state.terrain ||= load_terrain
      state.lava ||= load_lava
    end
  end

  def save_lines lines, file
    s = lines.map do |l|
      "#{l.x1},#{l.y1},#{l.x2},#{l.y2}"
    end.join("\n")
    gtk.write_file(file, s)
  end

  def save_level
    save_lines(state.terrain, 'level.txt')
    save_lines(state.lava, 'level_lava.txt')
    load_level force: true
  end

  def line_near_rect? rect, terrain
    geometry.intersect_rect?(rect, terrain[:rect])
  end

  def point_within_line? point, line
    return false if !point
    return false if !line
    return true
  end

  def calc_impacts x, dx, y, dy, radius
    results = { }
    results[:x] = x
    results[:y] = y
    results[:dx] = x
    results[:dy] = y
    results[:point] = { x: x, y: y }
    results[:rect] = { x: x - radius, y: y - radius, w: radius * 2, h: radius * 2 }
    results[:trajectory] = trajectory(results)
    results[:impacts] = terrain.find_all { |t| t && (line_near_rect? results[:rect], t) }.map do |t|
      intersection = geometry.line_intersect(results[:trajectory], t)
      {
        terrain: t,
        point: geometry.line_intersect(results[:trajectory], t),
        type: :terrain
      }
    end

    results[:impacts] += lava.find_all { |t| line_near_rect? results[:rect], t }.map do |t|
      intersection = geometry.line_intersect(results[:trajectory], t)
      {
        terrain: t,
        point: geometry.line_intersect(results[:trajectory], t),
        type: :lava
      }
    end

    results
  end

  def calc_potential_impacts
    impact_results = calc_impacts circle.x, circle.dx, circle.y, circle.dy, circle.radius
    circle.rect = impact_results[:rect]
    circle.trajectory = impact_results[:trajectory]
    circle.impacts = impact_results[:impacts]
  end

  def calc_terrains_to_monitor
    return unless circle.impacts
    circle.impact = nil
    circle.impacts.each do |i|
      future_circle = { x: circle.x + circle.dx, y: circle.y + circle.dy }
      circle.terrains_to_monitor[i[:terrain]] ||= {
        ray_start: geometry.ray_test(future_circle, i[:terrain]),
      }

      circle.terrains_to_monitor[i[:terrain]][:ray_current] = geometry.ray_test(future_circle, i[:terrain])
      if circle.terrains_to_monitor[i[:terrain]][:ray_start] != circle.terrains_to_monitor[i[:terrain]][:ray_current]
        circle.impact = i
        circle.ray_current = circle.terrains_to_monitor[i[:terrain]][:ray_current]
      end
    end
  end

  def impact_result body, impact
    infinity_alias = 1000
    r = {
      body: {},
      terrain: {},
      impact: {}
    }

    r[:body][:line] = body.trajectory.dup
    r[:body][:slope] = geometry.line_slope(body.trajectory, replace_infinity: infinity_alias)
    r[:body][:slope_sign] = r[:body][:slope].sign
    r[:body][:x] = body.x
    r[:body][:y] = body.y
    r[:body][:dy] = body.dy
    r[:body][:dx] = body.dx

    r[:terrain][:line] = impact[:terrain].dup
    r[:terrain][:slope] = geometry.line_slope(impact[:terrain], replace_infinity: infinity_alias)
    r[:terrain][:slope_sign] = r[:terrain][:slope].sign

    r[:impact][:angle] = -geometry.angle_between_lines(body.trajectory, impact[:terrain], replace_infinity: infinity_alias)
    r[:impact][:point] = { x: impact[:point].x, y: impact[:point].y }
    r[:impact][:same_slope_sign] = r[:body][:slope_sign] == r[:terrain][:slope_sign]
    r[:impact][:ray] = body.ray_current
    r[:body][:new_on_floor] = body.on_floor
    r[:body][:new_floor] = r[:terrain][:line]

    if r[:impact][:angle].abs < 90 && r[:terrain][:slope].abs < 3
      play_sound
      r[:body][:new_dy] = r[:body][:dy] * circle.elasticity * -1
      r[:body][:new_dx] = r[:body][:dx] * circle.elasticity
      r[:impact][:type] = :horizontal
      r[:body][:new_reason] = "-"
    elsif r[:impact][:angle].abs < 90 && r[:terrain][:slope].abs > 3
      play_sound
      r[:body][:new_dy] = r[:body][:dy] * 1.1
      r[:body][:new_dx] = r[:body][:dx] * -circle.elasticity
      r[:impact][:type] = :vertical
      r[:body][:new_reason] = "|"
    else
      play_sound
      r[:body][:new_dx] = r[:body][:dx] * -circle.elasticity
      r[:body][:new_dy] = r[:body][:dy] * -circle.elasticity
      r[:impact][:type] = :slanted
      r[:body][:new_reason] = "/"
    end

    r[:impact][:energy] = r[:body][:new_dx].abs + r[:body][:new_dy].abs

    if r[:impact][:energy] <= 0.3 && r[:terrain][:slope].abs < 4
      r[:body][:new_dx] = 0
      r[:body][:new_dy] = 0
      r[:impact][:energy] = 0
      r[:body][:new_on_floor] = true if r[:impact][:point].y < body.y
      r[:body][:new_floor] = r[:terrain][:line]
      r[:body][:new_reason] = "0"
    end

    r[:impact][:ray_next] = geometry.ray_test({ x: r[:body][:x] - (r[:body][:dx] * 1.1) + r[:body][:new_dx],
                                                y: r[:body][:y] - (r[:body][:dy] * 1.1) + r[:body][:new_dy] + state.gravity },
                                              r[:terrain][:line])

    if r[:impact][:ray_next] == r[:impact][:ray]
      r[:body][:new_dx] *= -1
      r[:body][:new_dy] *= -1
      r[:body][:new_reason] = "clip"
    end

    r
  end

  def game_over!
    circle.x = circle.check_point_x
    circle.y = circle.check_point_y
    circle.dx = 0
    circle.dy = 0
    circle.game_over_at = state.tick_count
  end

  def not_game_over!
    impact_history_entry = impact_result circle, circle.impact
    circle.impact_history << impact_history_entry
    circle.x -= circle.dx * 1.1
    circle.y -= circle.dy * 1.1
    circle.dx = impact_history_entry[:body][:new_dx]
    circle.dy = impact_history_entry[:body][:new_dy]
    circle.on_floor = impact_history_entry[:body][:new_on_floor]

    if circle.on_floor
      circle.check_point_at = state.tick_count
      circle.check_point_x = circle.x
      circle.check_point_y = circle.y
    end

    circle.previous_floor = circle.floor || {}
    circle.floor = impact_history_entry[:body][:new_floor] || {}
    circle.floor_point = impact_history_entry[:impact][:point]
    if circle.floor.slice(:x, :y, :x2, :y2) != circle.previous_floor.slice(:x, :y, :x2, :y2)
      new_relative_x = if circle.dx > 0
                         :right
                       elsif circle.dx < 0
                         :left
                       else
                         nil
                       end

      new_relative_y = if circle.dy > 0
                         :above
                       elsif circle.dy < 0
                         :below
                       else
                         nil
                       end

      circle.floor_relative_x = new_relative_x
      circle.floor_relative_y = new_relative_y
    end

    circle.impact = nil
    circle.terrains_to_monitor.clear
  end

  def calc_physics
    if args.state.god_mode
      calc_potential_impacts
      calc_terrains_to_monitor
      return
    end

    if circle.y < -700
      game_over
      return
    end

    return if state.game_over
    return if circle.on_floor
    circle.previous_dy = circle.dy
    circle.previous_dx = circle.dx
    circle.x  += circle.dx
    circle.y  += circle.dy
    args.state.distance_traveled ||= 0
    args.state.distance_traveled += circle.dx.abs + circle.dy.abs
    circle.dy += state.gravity
    calc_potential_impacts
    calc_terrains_to_monitor
    return unless circle.impact
    if circle.impact && circle.impact[:type] == :lava
      game_over!
    else
      not_game_over!
    end
  end

  def input_god_mode
    state.debug_mode = !state.debug_mode if inputs.keyboard.key_down.forward_slash

    # toggle god mode
    if inputs.keyboard.key_down.g
      state.god_mode = !state.god_mode
      state.potential_lift = 0
      circle.floor = nil
      circle.floor_point = nil
      circle.floor_relative_x = nil
      circle.floor_relative_y = nil
      circle.impact = nil
      circle.terrains_to_monitor.clear
      return
    end

    return unless state.god_mode

    circle.x = circle.x.to_i
    circle.y = circle.y.to_i

    # move god circle
    if inputs.keyboard.left || inputs.keyboard.a
      circle.x -= 20
    elsif inputs.keyboard.right || inputs.keyboard.d || inputs.keyboard.f
      circle.x += 20
    end

    if inputs.keyboard.up || inputs.keyboard.w
      circle.y += 20
    elsif inputs.keyboard.down || inputs.keyboard.s
      circle.y -= 20
    end

    # delete terrain
    if inputs.keyboard.key_down.x
      calc_terrains_to_monitor
      state.terrain = state.terrain.reject do |t|
        t[:rect].intersect_rect? circle.rect
      end

      state.lava = state.lava.reject do |t|
        t[:rect].intersect_rect? circle.rect
      end

      calc_potential_impacts
      save_level
    end

    # change terrain type
    if inputs.keyboard.key_down.l
      if state.line_mode == :terrain
        state.line_mode = :lava
      else
        state.line_mode = :terrain
      end
    end

    if inputs.mouse.click && !state.point_one
      state.point_one = inputs.mouse.click.point
    elsif inputs.mouse.click && state.point_one
      l = [*state.point_one, *inputs.mouse.click.point]
      l = [l.x  - state.camera.x,
           l.y  - state.camera.y,
           l.x2 - state.camera.x,
           l.y2 - state.camera.y].line.to_hash
      l[:rect] = rect_for_line l
      if state.line_mode == :terrain
        state.terrain << l
      else
        state.lava << l
      end
      save_level
      next_x = inputs.mouse.click.point.x - 640
      next_y = inputs.mouse.click.point.y - 360
      circle.x += next_x
      circle.y += next_y
      state.point_one = nil
    elsif inputs.keyboard.one
      state.point_one = [circle.x + camera.x, circle.y+ camera.y]
    end

    # cancel chain lines
    if inputs.keyboard.key_down.nine || inputs.keyboard.key_down.escape || inputs.keyboard.key_up.six || inputs.keyboard.key_up.one
      state.point_one = nil
    end
  end

  def play_sound
    return if state.sound_debounce > 0
    state.sound_debounce = 5
    outputs.sounds << "sounds/03#{"%02d" % state.sound_index}.wav"
    state.sound_index += 1
    if state.sound_index > 21
      state.sound_index = 1
    end
  end

  def input_game
    if inputs.keyboard.down || inputs.keyboard.space
      circle.potential_lift += 0.03
      circle.potential_lift = circle.potential_lift.lesser(10)
    elsif inputs.keyboard.key_up.down || inputs.keyboard.key_up.space
      play_sound
      circle.dy += circle.angle.vector_y circle.potential_lift
      circle.dx += circle.angle.vector_x circle.potential_lift

      if circle.on_floor
        if circle.floor_relative_y == :above
          circle.y += circle.potential_lift.abs * 2
        elsif circle.floor_relative_y == :below
          circle.y -= circle.potential_lift.abs * 2
        end
      end

      circle.on_floor = false
      circle.potential_lift = 0
      circle.terrains_to_monitor.clear
      circle.impact_history.clear
      circle.impact = nil
      calc_physics
    end

    # aim probe
    if inputs.keyboard.right || inputs.keyboard.a
      circle.angle -= 2
    elsif inputs.keyboard.left || inputs.keyboard.d
      circle.angle += 2
    end
  end

  def input
    input_god_mode
    input_game
  end

  def calc_camera
    state.camera.target_x = 640 - circle.x
    state.camera.target_y = 360 - circle.y
    xdiff = state.camera.target_x - state.camera.x
    ydiff = state.camera.target_y - state.camera.y
    state.camera.x += xdiff * camera.follow_speed
    state.camera.y += ydiff * camera.follow_speed
  end

  def calc
    state.sound_debounce ||= 0
    state.sound_debounce -= 1
    state.sound_debounce = 0 if state.sound_debounce < 0
    if state.god_mode
      circle.dy *= 0.1
      circle.dx *= 0.1
    end
    calc_camera
    state.whisp_queue ||= []
    if state.tick_count.mod_zero?(4)
      state.whisp_queue << {
        x: -300,
        y: 1400 * rand,
        speed: 2.randomize(:ratio) + 3,
        w: 20,
        h: 20, path: 'sprites/whisp.png',
        a: 0,
        created_at: state.tick_count,
        angle: 0,
        r: 100,
        g: 128 + 128 * rand,
        b: 128 + 128 * rand
      }
    end

    state.whisp_queue.each do |w|
      w.x += w[:speed] * 2
      w.x -= circle.dx * 0.3
      w.y -= w[:speed]
      w.y -= circle.dy * 0.3
      w.angle += w[:speed]
      w.a = w[:created_at].ease(30) * 255
    end

    state.whisp_queue = state.whisp_queue.reject { |w| w[:x] > 1280 }

    if state.tick_count.mod_zero?(2) && (circle.dx != 0 || circle.dy != 0)
      circle.after_images << {
        x: circle.x,
        y: circle.y,
        w: circle.radius,
        h: circle.radius,
        a: 255,
        created_at: state.tick_count
      }
    end

    circle.after_images.each do |ai|
      ai.a = ai[:created_at].ease(10, :flip) * 255
    end

    circle.after_images = circle.after_images.reject { |ai| ai[:created_at].elapsed_time > 10 }
    calc_physics
  end

  def circle
    state.circle
  end

  def camera
    state.camera
  end

  def terrain
    state.terrain
  end

  def lava
    state.lava
  end
end

# $gtk.reset

def tick args
  args.outputs.background_color = [0, 0, 0]
  if args.inputs.keyboard.r
    args.gtk.reset
    return
  end
  # uncomment the line below to slow down the game so you
  # can see each tick as it passes
  # args.gtk.slowmo! 30
  $game ||= FallingCircle.new
  $game.args = args
  $game.tick
end

def reset
  $game = nil
end

    The Little Probe - Data - level.txt link

    # ./samples/99_genre_platformer/the_little_probe/data/level.txt
640,8840,1180,8840
-60,10220,0,9960
-60,10220,0,10500
0,10500,0,10780
0,10780,40,10900
500,10920,760,10960
300,10560,820,10600
420,10320,700,10300
820,10600,1500,10600
1500,10600,1940,10600
1940,10600,2380,10580
2380,10580,2800,10620
2240,11080,2480,11020
2000,11120,2240,11080
1760,11180,2000,11120
1620,11180,1760,11180
1500,11220,1620,11180
1180,11280,1340,11220
1040,11240,1180,11280
840,11280,1040,11240
640,11280,840,11280
500,11220,640,11280
420,11140,500,11220
240,11100,420,11140
100,11120,240,11100
0,11180,100,11120
-160,11220,0,11180
-260,11240,-160,11220
1340,11220,1500,11220
960,13300,1280,13060
1280,13060,1540,12860
1540,12860,1820,12700
1820,12700,2080,12520
2080,12520,2240,12400
2240,12400,2240,12240
2240,12240,2400,12080
2400,12080,2560,11920
2560,11920,2640,11740
2640,11740,2740,11580
2740,11580,2800,11400
2800,11400,2800,11240
2740,11140,2800,11240
2700,11040,2740,11140
2700,11040,2740,10960
2740,10960,2740,10920
2700,10900,2740,10920
2380,10900,2700,10900
2040,10920,2380,10900
1720,10940,2040,10920
1380,11000,1720,10940
1180,10980,1380,11000
900,10980,1180,10980
760,10960,900,10980
240,10960,500,10920
40,10900,240,10960
0,9700,0,9960
-60,9500,0,9700
-60,9420,-60,9500
-60,9420,-60,9340
-60,9340,-60,9280
-60,9120,-60,9280
-60,8940,-60,9120
-60,8940,-60,8780
-60,8780,0,8700
0,8700,40,8680
40,8680,240,8700
240,8700,360,8780
360,8780,640,8840
1420,8400,1540,8480
1540,8480,1680,8500
1680,8500,1940,8460
1180,8840,1280,8880
1280,8880,1340,8860
1340,8860,1720,8860
1720,8860,1820,8920
1820,8920,1820,9140
1820,9140,1820,9280
1820,9460,1820,9280
1760,9480,1820,9460
1640,9480,1760,9480
1540,9500,1640,9480
1340,9500,1540,9500
1100,9500,1340,9500
1040,9540,1100,9500
960,9540,1040,9540
300,9420,360,9460
240,9440,300,9420
180,9600,240,9440
120,9660,180,9600
100,9820,120,9660
100,9820,120,9860
120,9860,140,9900
140,9900,140,10000
140,10440,180,10540
100,10080,140,10000
100,10080,140,10100
140,10100,140,10440
180,10540,300,10560
2140,9560,2140,9640
2140,9720,2140,9640
1880,9780,2140,9720
1720,9780,1880,9780
1620,9740,1720,9780
1500,9780,1620,9740
1380,9780,1500,9780
1340,9820,1380,9780
1200,9820,1340,9820
1100,9780,1200,9820
900,9780,1100,9780
820,9720,900,9780
540,9720,820,9720
360,9840,540,9720
360,9840,360,9960
360,9960,360,10080
360,10140,360,10080
360,10140,360,10240
360,10240,420,10320
700,10300,820,10280
820,10280,820,10280
820,10280,900,10320
900,10320,1040,10300
1040,10300,1200,10320
1200,10320,1380,10280
1380,10280,1500,10300
1500,10300,1760,10300
2800,10620,2840,10600
2840,10600,2900,10600
2900,10600,3000,10620
3000,10620,3080,10620
3080,10620,3140,10600
3140,10540,3140,10600
3140,10540,3140,10460
3140,10460,3140,10360
3140,10360,3140,10260
3140,10260,3140,10140
3140,10140,3140,10000
3140,10000,3140,9860
3140,9860,3160,9720
3160,9720,3160,9580
3160,9580,3160,9440
3160,9300,3160,9440
3160,9300,3160,9140
3160,9140,3160,8980
3160,8980,3160,8820
3160,8820,3160,8680
3160,8680,3160,8520
1760,10300,1880,10300
660,9500,960,9540
640,9460,660,9500
360,9460,640,9460
-480,10760,-440,10880
-480,11020,-440,10880
-480,11160,-260,11240
-480,11020,-480,11160
-600,11420,-380,11320
-380,11320,-200,11340
-200,11340,0,11340
0,11340,180,11340
960,13420,960,13300
960,13420,960,13520
960,13520,1000,13560
1000,13560,1040,13540
1040,13540,1200,13440
1200,13440,1380,13380
1380,13380,1620,13300
1620,13300,1820,13220
1820,13220,2000,13200
2000,13200,2240,13200
2240,13200,2440,13160
2440,13160,2640,13040
-480,10760,-440,10620
-440,10620,-360,10560
-380,10460,-360,10560
-380,10460,-360,10300
-380,10140,-360,10300
-380,10140,-380,10040
-380,9880,-380,10040
-380,9720,-380,9880
-380,9720,-380,9540
-380,9360,-380,9540
-380,9180,-380,9360
-380,9180,-380,9000
-380,8840,-380,9000
-380,8840,-380,8760
-380,8760,-380,8620
-380,8620,-380,8520
-380,8520,-360,8400
-360,8400,-100,8400
-100,8400,-60,8420
-60,8420,240,8440
240,8440,240,8380
240,8380,500,8440
500,8440,760,8460
760,8460,1000,8400
1000,8400,1180,8420
1180,8420,1420,8400
1940,8460,2140,8420
2140,8420,2200,8520
2200,8680,2200,8520
2140,8840,2200,8680
2140,8840,2140,9020
2140,9100,2140,9020
2140,9200,2140,9100
2140,9200,2200,9320
2200,9320,2200,9440
2140,9560,2200,9440
1880,10300,2200,10280
2200,10280,2480,10260
2480,10260,2700,10240
2700,10240,2840,10180
2840,10180,2900,10060
2900,9860,2900,10060
2900,9640,2900,9860
2900,9640,2900,9500
2900,9460,2900,9500
2740,9460,2900,9460
2700,9460,2740,9460
2700,9360,2700,9460
2700,9320,2700,9360
2600,9320,2700,9320
2600,9260,2600,9320
2600,9200,2600,9260
2480,9120,2600,9200
2440,9080,2480,9120
2380,9080,2440,9080
2320,9060,2380,9080
2320,8860,2320,9060
2320,8860,2380,8840
2380,8840,2480,8860
2480,8860,2600,8840
2600,8840,2740,8840
2740,8840,2840,8800
2840,8800,2900,8700
2900,8600,2900,8700
2900,8480,2900,8600
2900,8380,2900,8480
2900,8380,2900,8260
2900,8260,2900,8140
2900,8140,2900,8020
2900,8020,2900,7900
2900,7820,2900,7900
2900,7820,2900,7740
2900,7660,2900,7740
2900,7560,2900,7660
2900,7460,2900,7560
2900,7460,2900,7360
2900,7260,2900,7360
2840,7160,2900,7260
2800,7080,2840,7160
2700,7100,2800,7080
2560,7120,2700,7100
2400,7100,2560,7120
2320,7100,2400,7100
2140,7100,2320,7100
2040,7080,2140,7100
1940,7080,2040,7080
1820,7140,1940,7080
1680,7140,1820,7140
1540,7140,1680,7140
1420,7220,1540,7140
1280,7220,1380,7220
1140,7200,1280,7220
1000,7220,1140,7200
760,7280,900,7320
540,7220,760,7280
300,7180,540,7220
180,7120,180,7160
40,7140,180,7120
-60,7160,40,7140
-200,7120,-60,7160
180,7160,300,7180
-260,7060,-200,7120
-260,6980,-260,7060
-260,6880,-260,6980
-260,6880,-260,6820
-260,6820,-200,6760
-200,6760,-100,6740
-100,6740,-60,6740
-60,6740,40,6740
40,6740,300,6800
300,6800,420,6760
420,6760,500,6740
500,6740,540,6760
540,6760,540,6760
540,6760,640,6780
640,6660,640,6780
580,6580,640,6660
580,6440,580,6580
580,6440,640,6320
640,6320,640,6180
580,6080,640,6180
580,6080,640,5960
640,5960,640,5840
640,5840,640,5700
640,5700,660,5560
660,5560,660,5440
660,5440,660,5300
660,5140,660,5300
660,5140,660,5000
660,5000,660,4880
660,4880,820,4860
820,4860,1000,4840
1000,4840,1100,4860
1100,4860,1280,4860
1280,4860,1420,4840
1420,4840,1580,4860
1580,4860,1720,4820
1720,4820,1880,4860
1880,4860,2000,4840
2000,4840,2140,4840
2140,4840,2320,4860
2320,4860,2440,4880
2440,4880,2600,4880
2600,4880,2800,4880
2800,4880,2900,4880
2900,4880,2900,4820
2900,4740,2900,4820
2800,4700,2900,4740
2520,4680,2800,4700
2240,4660,2520,4680
1940,4620,2240,4660
1820,4580,1940,4620
1820,4500,1820,4580
1820,4500,1880,4420
1880,4420,2000,4420
2000,4420,2200,4420
2200,4420,2400,4440
2400,4440,2600,4440
2600,4440,2840,4440
2840,4440,2900,4400
2740,4260,2900,4280
2600,4240,2740,4260
2480,4280,2600,4240
2320,4240,2480,4280
2140,4220,2320,4240
1940,4220,2140,4220
1880,4160,1940,4220
1880,4160,1880,4080
1880,4080,2040,4040
2040,4040,2240,4060
2240,4060,2400,4040
2400,4040,2600,4060
2600,4060,2740,4020
2740,4020,2840,3940
2840,3780,2840,3940
2740,3660,2840,3780
2700,3680,2740,3660
2520,3700,2700,3680
2380,3700,2520,3700
2200,3720,2380,3700
2040,3720,2200,3720
1880,3700,2040,3720
1820,3680,1880,3700
1760,3600,1820,3680
1760,3600,1820,3480
1820,3480,1880,3440
1880,3440,1960,3460
1960,3460,2140,3460
2140,3460,2380,3460
2380,3460,2640,3440
2640,3440,2900,3380
2840,3280,2900,3380
2840,3280,2900,3200
2900,3200,2900,3140
2840,3020,2900,3140
2800,2960,2840,3020
2700,3000,2800,2960
2600,2980,2700,3000
2380,3000,2600,2980
2140,3000,2380,3000
1880,3000,2140,3000
1720,3040,1880,3000
1640,2960,1720,3040
1500,2940,1640,2960
1340,3000,1500,2940
1240,3000,1340,3000
1140,3020,1240,3000
1040,3000,1140,3020
960,2960,1040,3000
900,2960,960,2960
840,2840,900,2960
700,2820,840,2840
540,2820,700,2820
420,2820,540,2820
180,2800,420,2820
60,2780,180,2800
-60,2800,60,2780
-160,2760,-60,2800
-260,2740,-160,2760
-300,2640,-260,2740
-360,2560,-300,2640
-380,2460,-360,2560
-380,2460,-300,2380
-300,2300,-300,2380
-300,2300,-300,2220
-300,2100,-300,2220
-300,2100,-300,2040
-300,2040,-160,2040
-160,2040,-60,2040
-60,2040,60,2040
60,2040,180,2040
180,2040,360,2040
360,2040,540,2040
540,2040,700,2080
660,2160,700,2080
660,2160,700,2260
660,2380,700,2260
500,2340,660,2380
360,2340,500,2340
240,2340,360,2340
40,2320,240,2340
-60,2320,40,2320
-100,2380,-60,2320
-100,2380,-100,2460
-100,2460,-100,2540
-100,2540,0,2560
0,2560,140,2600
140,2600,300,2600
300,2600,460,2600
460,2600,640,2600
640,2600,760,2580
760,2580,820,2560
820,2560,820,2500
820,2500,820,2400
820,2400,840,2320
840,2320,840,2240
820,2120,840,2240
820,2020,820,2120
820,1900,820,2020
760,1840,820,1900
640,1840,760,1840
500,1840,640,1840
300,1860,420,1880
180,1840,300,1860
420,1880,500,1840
0,1840,180,1840
-60,1860,0,1840
-160,1840,-60,1860
-200,1800,-160,1840
-260,1760,-200,1800
-260,1680,-260,1760
-260,1620,-260,1680
-260,1540,-260,1620
-260,1540,-260,1460
-300,1420,-260,1460
-300,1420,-300,1340
-300,1340,-260,1260
-260,1260,-260,1160
-260,1060,-260,1160
-260,1060,-260,960
-260,880,-260,960
-260,880,-260,780
-260,780,-260,680
-300,580,-260,680
-300,580,-300,480
-300,480,-260,400
-300,320,-260,400
-300,320,-300,240
-300,240,-200,220
-200,220,-200,160
-200,160,-100,140
-100,140,0,120
0,120,60,120
60,120,180,120
180,120,300,120
300,120,420,140
420,140,580,180
580,180,760,180
760,180,900,180
960,180,1100,180
1100,180,1340,200
1340,200,1580,200
1580,200,1720,180
1720,180,2000,140
2000,140,2240,140
2240,140,2480,140
2520,140,2800,160
2800,160,3000,160
3000,160,3140,160
3140,260,3140,160
3140,260,3140,380
3080,500,3140,380
3080,620,3080,500
3080,620,3080,740
3080,740,3080,840
3080,960,3080,840
3080,1080,3080,960
3080,1080,3080,1200
3080,1200,3080,1340
3080,1340,3080,1460
3080,1580,3080,1460
3080,1700,3080,1580
3080,1700,3080,1760
3080,1760,3200,1760
3200,1760,3320,1760
3320,1760,3520,1760
3520,1760,3680,1740
3680,1740,3780,1700
3780,1700,3840,1620
3840,1620,3840,1520
3840,1520,3840,1420
3840,1320,3840,1420
3840,1120,3840,1320
3840,1120,3840,940
3840,940,3840,760
3780,600,3840,760
3780,600,3780,440
3780,320,3780,440
3780,320,3780,160
3780,60,3780,160
3780,60,4020,60
4020,60,4260,40
4260,40,4500,40
4500,40,4740,40
4740,40,4840,20
4840,20,4880,80
4880,80,5080,40
5080,40,5280,20
5280,20,5500,0
5500,0,5720,0
5720,0,5940,60
5940,60,6240,60
6240,60,6540,20
6540,20,6840,20
6840,20,7040,0
7040,0,7140,0
7140,0,7400,20
7400,20,7680,0
7680,0,7940,0
7940,0,8200,-20
8200,-20,8360,20
8360,20,8560,-40
8560,-40,8760,0
8760,0,8880,40
8880,120,8880,40
8840,220,8840,120
8620,240,8840,220
8420,260,8620,240
8200,280,8420,260
7940,280,8200,280
7760,240,7940,280
7560,220,7760,240
7360,280,7560,220
7140,260,7360,280
6940,240,7140,260
6720,220,6940,240
6480,220,6720,220
6360,300,6480,220
6240,300,6360,300
6200,500,6240,300
6200,500,6360,540
6360,540,6540,520
6540,520,6720,480
6720,480,6880,460
6880,460,7080,500
7080,500,7320,500
7320,500,7680,500
7680,620,7680,500
7520,640,7680,620
7360,640,7520,640
7200,640,7360,640
7040,660,7200,640
6880,720,7040,660
6720,700,6880,720
6540,700,6720,700
6420,760,6540,700
6280,740,6420,760
6240,760,6280,740
6200,920,6240,760
6200,920,6360,960
6360,960,6540,960
6540,960,6720,960
6720,960,6760,980
6760,980,6880,940
6880,940,7080,940
7080,940,7280,940
7280,940,7520,920
7520,920,7760,900
7760,900,7980,860
7980,860,8100,880
8100,880,8280,900
8280,900,8500,820
8500,820,8700,820
8700,820,8760,840
8760,960,8760,840
8700,1040,8760,960
8560,1060,8700,1040
8460,1080,8560,1060
8360,1040,8460,1080
8280,1080,8360,1040
8160,1120,8280,1080
8040,1120,8160,1120
7940,1100,8040,1120
7800,1120,7940,1100
7680,1120,7800,1120
7520,1100,7680,1120
7360,1100,7520,1100
7200,1120,7360,1100
7040,1180,7200,1120
6880,1160,7040,1180
6720,1160,6880,1160
6540,1160,6720,1160
6360,1160,6540,1160
6200,1160,6360,1160
6040,1220,6200,1160
6040,1220,6040,1400
6040,1400,6200,1440
6200,1440,6320,1440
6320,1440,6440,1440
6600,1440,6760,1440
6760,1440,6940,1420
6440,1440,6600,1440
6940,1420,7280,1400
7280,1400,7560,1400
7560,1400,7760,1400
7760,1400,7940,1360
7940,1360,8100,1380
8100,1380,8280,1340
8280,1340,8460,1320
8660,1300,8760,1360
8460,1320,8660,1300
8760,1360,8800,1500
8800,1660,8800,1500
8800,1660,8800,1820
8700,1840,8800,1820
8620,1860,8700,1840
8560,1800,8620,1860
8560,1800,8620,1680
8500,1640,8620,1680
8420,1680,8500,1640
8280,1680,8420,1680
8160,1680,8280,1680
7900,1680,8160,1680
7680,1680,7900,1680
7400,1660,7680,1680
7140,1680,7400,1660
6880,1640,7140,1680
6040,1820,6320,1780
5900,1840,6040,1820
6640,1700,6880,1640
6320,1780,6640,1700
5840,2040,5900,1840
5840,2040,5840,2220
5840,2220,5840,2320
5840,2460,5840,2320
5840,2560,5840,2460
5840,2560,5960,2620
5960,2620,6200,2620
6200,2620,6380,2600
6380,2600,6600,2580
6600,2580,6800,2600
6800,2600,7040,2580
7040,2580,7280,2580
7280,2580,7480,2560
7760,2540,7980,2520
7980,2520,8160,2500
7480,2560,7760,2540
8160,2500,8160,2420
8160,2420,8160,2320
8160,2180,8160,2320
7980,2160,8160,2180
7800,2180,7980,2160
7600,2200,7800,2180
7400,2200,7600,2200
6960,2200,7200,2200
7200,2200,7400,2200
6720,2200,6960,2200
6540,2180,6720,2200
6320,2200,6540,2180
6240,2160,6320,2200
6240,2160,6240,2040
6240,2040,6240,1940
6240,1940,6440,1940
6440,1940,6720,1940
6720,1940,6940,1920
7520,1920,7760,1920
6940,1920,7280,1920
7280,1920,7520,1920
7760,1920,8100,1900
8100,1900,8420,1900
8420,1900,8460,1940
8460,2120,8460,1940
8460,2280,8460,2120
8460,2280,8560,2420
8560,2420,8660,2380
8660,2380,8800,2340
8800,2340,8840,2400
8840,2520,8840,2400
8800,2620,8840,2520
8800,2740,8800,2620
8800,2860,8800,2740
8800,2940,8800,2860
8760,2980,8800,2940
8660,2980,8760,2980
8620,2960,8660,2980
8560,2880,8620,2960
8560,2880,8560,2780
8500,2740,8560,2780
8420,2760,8500,2740
8420,2840,8420,2760
8420,2840,8420,2940
8420,3040,8420,2940
8420,3160,8420,3040
8420,3280,8420,3380
8420,3280,8420,3160
8420,3380,8620,3460
8620,3460,8760,3460
8760,3460,8840,3400
8840,3400,8960,3400
8960,3400,9000,3500
9000,3700,9000,3500
9000,3900,9000,3700
9000,4080,9000,3900
9000,4280,9000,4080
9000,4500,9000,4280
9000,4620,9000,4500
9000,4780,9000,4620
9000,4780,9000,4960
9000,5120,9000,4960
9000,5120,9000,5300
8960,5460,9000,5300
8920,5620,8960,5460
8920,5620,8920,5800
8920,5800,8920,5960
8920,5960,8920,6120
8920,6120,8960,6300
8960,6300,8960,6480
8960,6660,8960,6480
8960,6860,8960,6660
8960,7040,8960,6860
8920,7420,8920,7220
8920,7420,8960,7620
8960,7620,8960,7800
8960,7800,8960,8000
8960,8000,8960,8180
8960,8180,8960,8380
8960,8580,8960,8380
8920,8800,8960,8580
8880,9000,8920,8800
8840,9180,8880,9000
8800,9220,8840,9180
8800,9220,8840,9340
8760,9380,8840,9340
8560,9340,8760,9380
8360,9360,8560,9340
8160,9360,8360,9360
8040,9340,8160,9360
7860,9360,8040,9340
7680,9360,7860,9360
7520,9360,7680,9360
7420,9260,7520,9360
7400,9080,7420,9260
7400,9080,7420,8860
7420,8860,7440,8720
7440,8720,7480,8660
7480,8660,7520,8540
7520,8540,7600,8460
7600,8460,7800,8480
7800,8480,8040,8480
8040,8480,8280,8480
8280,8480,8500,8460
8500,8460,8620,8440
8620,8440,8660,8340
8660,8340,8660,8220
8660,8220,8700,8080
8700,8080,8700,7920
8700,7920,8700,7760
8700,7760,8700,7620
8700,7480,8700,7620
8700,7480,8700,7320
8700,7160,8700,7320
8920,7220,8960,7040
8660,7040,8700,7160
8660,7040,8700,6880
8660,6700,8700,6880
8660,6700,8700,6580
8700,6460,8700,6580
8700,6460,8700,6320
8700,6160,8700,6320
8700,6160,8760,6020
8760,6020,8760,5860
8760,5860,8760,5700
8760,5700,8760,5540
8760,5540,8760,5360
8760,5360,8760,5180
8760,5000,8760,5180
8700,4820,8760,5000
8560,4740,8700,4820
8420,4700,8560,4740
8280,4700,8420,4700
8100,4700,8280,4700
7980,4700,8100,4700
7820,4740,7980,4700
7800,4920,7820,4740
7800,4920,7900,4960
7900,4960,8060,4980
8060,4980,8220,5000
8220,5000,8420,5040
8420,5040,8460,5120
8460,5180,8460,5120
8360,5200,8460,5180
8360,5280,8360,5200
8160,5300,8360,5280
8040,5260,8160,5300
7860,5220,8040,5260
7720,5160,7860,5220
7640,5120,7720,5160
7480,5120,7640,5120
7240,5120,7480,5120
7000,5120,7240,5120
6800,5160,7000,5120
6640,5220,6800,5160
6600,5360,6640,5220
6600,5460,6600,5360
6480,5520,6600,5460
6240,5540,6480,5520
5980,5540,6240,5540
5740,5540,5980,5540
5500,5520,5740,5540
5400,5520,5500,5520
5280,5540,5400,5520
5080,5540,5280,5540
4940,5540,5080,5540
4760,5540,4940,5540
4600,5540,4760,5540
4440,5560,4600,5540
4040,5580,4120,5520
4260,5540,4440,5560
4120,5520,4260,5540
4020,5720,4040,5580
4020,5840,4020,5720
4020,5840,4080,5940
4080,5940,4120,6040
4120,6040,4200,6080
4200,6080,4340,6080
4340,6080,4500,6060
4500,6060,4700,6060
4700,6060,4880,6060
4880,6060,5080,6060
5080,6060,5280,6080
5280,6080,5440,6100
5440,6100,5660,6100
5660,6100,5900,6080
5900,6080,6120,6080
6120,6080,6360,6080
6360,6080,6480,6100
6480,6100,6540,6060
6540,6060,6720,6060
6720,6060,6940,6060
6940,6060,7140,6060
7400,6060,7600,6060
7140,6060,7400,6060
7600,6060,7800,6060
7800,6060,7860,6080
7860,6080,8060,6080
8060,6080,8220,6080
8220,6080,8320,6140
8320,6140,8360,6300
8320,6460,8360,6300
8320,6620,8320,6460
8320,6800,8320,6620
8320,6960,8320,6800
8320,6960,8360,7120
8320,7280,8360,7120
8320,7440,8320,7280
8320,7600,8320,7440
8100,7580,8220,7600
8220,7600,8320,7600
7900,7560,8100,7580
7680,7560,7900,7560
7480,7580,7680,7560
7280,7580,7480,7580
7080,7580,7280,7580
7000,7600,7080,7580
6880,7600,7000,7600
6800,7580,6880,7600
6640,7580,6800,7580
6540,7580,6640,7580
6380,7600,6540,7580
6280,7620,6380,7600
6240,7700,6280,7620
6240,7700,6240,7800
6240,7840,6240,7800
6080,7840,6240,7840
5960,7820,6080,7840
5660,7840,5800,7840
5500,7800,5660,7840
5440,7700,5500,7800
5800,7840,5960,7820
5440,7540,5440,7700
5440,7440,5440,7540
5440,7320,5440,7440
5400,7320,5440,7320
5340,7400,5400,7320
5340,7400,5340,7500
5340,7600,5340,7500
5340,7600,5340,7720
5340,7720,5340,7860
5340,7860,5340,7960
5340,7960,5440,8020
5440,8020,5560,8020
5560,8020,5720,8040
5720,8040,5900,8060
5900,8060,6080,8060
6080,8060,6240,8060
6720,8040,6840,8060
6240,8060,6480,8040
6480,8040,6720,8040
6840,8060,6940,8060
6940,8060,7080,8120
7080,8120,7140,8180
7140,8460,7140,8320
7140,8620,7140,8460
7140,8620,7140,8740
7140,8860,7140,8740
7140,8960,7140,8860
7140,8960,7200,9080
7140,9200,7200,9080
7140,9200,7200,9320
7200,9320,7200,9460
7200,9760,7200,9900
7200,9620,7200,9460
7200,9620,7200,9760
7200,9900,7200,10060
7200,10220,7200,10060
7200,10360,7200,10220
7140,10400,7200,10360
6880,10400,7140,10400
6640,10360,6880,10400
6420,10360,6640,10360
6160,10380,6420,10360
5940,10340,6160,10380
5720,10320,5940,10340
5500,10340,5720,10320
5280,10300,5500,10340
5080,10300,5280,10300
4840,10280,5080,10300
4700,10280,4840,10280
4540,10280,4700,10280
4360,10280,4540,10280
4200,10300,4360,10280
4040,10380,4200,10300
4020,10500,4040,10380
3980,10640,4020,10500
3980,10640,3980,10760
3980,10760,4020,10920
4020,10920,4080,11000
4080,11000,4340,11020
4340,11020,4600,11060
4600,11060,4840,11040
4840,11040,4880,10960
4880,10740,4880,10960
4880,10740,4880,10600
4880,10600,5080,10560
5080,10560,5340,10620
5340,10620,5660,10620
5660,10620,6040,10600
6040,10600,6120,10620
6120,10620,6240,10720
6240,10720,6420,10740
6420,10740,6640,10760
6640,10760,6880,10780
7140,10780,7400,10780
6880,10780,7140,10780
7400,10780,7680,10780
7680,10780,8100,10760
8100,10760,8460,10740
8460,10740,8700,10760
8800,10840,8800,10980
8700,10760,8800,10840
8760,11200,8800,10980
8760,11200,8760,11380
8760,11380,8800,11560
8760,11680,8800,11560
8760,11760,8760,11680
8760,11760,8760,11920
8760,11920,8800,12080
8800,12200,8800,12080
8700,12240,8800,12200
8560,12220,8700,12240
8360,12220,8560,12220
8160,12240,8360,12220
7720,12220,7980,12220
7980,12220,8160,12240
7400,12200,7720,12220
7200,12180,7400,12200
7000,12160,7200,12180
6800,12160,7000,12160
6280,12140,6380,12180
6120,12180,6280,12140
6540,12180,6800,12160
6380,12180,6540,12180
5900,12200,6120,12180
5620,12180,5900,12200
5340,12120,5620,12180
5140,12100,5340,12120
4980,12120,5140,12100
4840,12120,4980,12120
4700,12200,4840,12120
4700,12380,4700,12200
4740,12480,4940,12520
4700,12380,4740,12480
4940,12520,5160,12560
5160,12560,5340,12600
5340,12600,5400,12600
5400,12600,5500,12600
5500,12600,5620,12600
5620,12600,5720,12560
5720,12560,5800,12440
5800,12440,5900,12380
5900,12380,6120,12420
6120,12420,6380,12440
6380,12440,6600,12460
6720,12460,6840,12520
6840,12520,6960,12520
6600,12460,6720,12460
6960,12520,7040,12500
7040,12500,7140,12440
7200,12440,7360,12500
7360,12500,7600,12560
7600,12560,7860,12600
7860,12600,8060,12500
8100,12500,8200,12340
8200,12340,8360,12360
8360,12360,8560,12400
8560,12400,8660,12420
8660,12420,8840,12400
8840,12400,9000,12360
9000,12360,9000,12360
2900,4400,2900,4280
900,7320,1000,7220
2640,13040,2900,12920
2900,12920,3160,12840
3480,12760,3780,12620
3780,12620,4020,12460
4300,12360,4440,12260
4020,12460,4300,12360
3160,12840,3480,12760
4440,12080,4440,12260
4440,12080,4440,11880
4440,11880,4440,11720
4440,11720,4600,11720
4600,11720,4760,11740
4760,11740,4980,11760
4980,11760,5160,11760
5160,11760,5340,11780
6000,11860,6120,11820
5340,11780,5620,11820
5620,11820,6000,11860
6120,11820,6360,11820
6360,11820,6640,11860
6940,11920,7240,11940
7240,11940,7520,11960
7520,11960,7860,11960
7860,11960,8100,11920
8100,11920,8420,11940
8420,11940,8460,11960
8460,11960,8500,11860
8460,11760,8500,11860
8320,11720,8460,11760
8160,11720,8320,11720
7940,11720,8160,11720
7720,11700,7940,11720
7520,11680,7720,11700
7320,11680,7520,11680
7200,11620,7320,11680
7200,11620,7200,11500
7200,11500,7280,11440
7280,11440,7420,11440
7420,11440,7600,11440
7600,11440,7980,11460
7980,11460,8160,11460
8160,11460,8360,11460
8360,11460,8460,11400
8420,11060,8500,11200
8280,11040,8420,11060
8100,11060,8280,11040
8460,11400,8500,11200
7800,11060,8100,11060
7520,11060,7800,11060
7240,11060,7520,11060
6940,11040,7240,11060
6640,11000,6940,11040
6420,10980,6640,11000
6360,11060,6420,10980
6360,11180,6360,11060
6200,11280,6360,11180
5960,11300,6200,11280
5720,11280,5960,11300
5500,11280,5720,11280
4940,11300,5200,11280
4660,11260,4940,11300
4440,11280,4660,11260
4260,11280,4440,11280
4220,11220,4260,11280
4080,11280,4220,11220
3980,11420,4080,11280
3980,11420,4040,11620
4040,11620,4040,11820
3980,11960,4040,11820
3840,12000,3980,11960
3720,11940,3840,12000
3680,11800,3720,11940
3680,11580,3680,11800
3680,11360,3680,11580
3680,11360,3680,11260
3680,11080,3680,11260
3680,11080,3680,10880
3680,10700,3680,10880
3680,10700,3680,10620
3680,10480,3680,10620
3680,10480,3680,10300
3680,10300,3680,10100
3680,10100,3680,9940
3680,9940,3720,9860
3720,9860,3920,9900
3920,9900,4220,9880
4980,9940,5340,9960
4220,9880,4540,9900
4540,9900,4980,9940
5340,9960,5620,9960
5620,9960,5900,9960
5900,9960,6160,10000
6160,10000,6480,10000
6480,10000,6720,10000
6720,10000,6880,9860
6880,9860,6880,9520
6880,9520,6940,9340
6940,9120,6940,9340
6940,9120,6940,8920
6940,8700,6940,8920
6880,8500,6940,8700
6880,8320,6880,8500
7140,8320,7140,8180
6760,8260,6880,8320
6540,8240,6760,8260
6420,8180,6540,8240
6280,8240,6420,8180
6160,8300,6280,8240
6120,8400,6160,8300
6080,8520,6120,8400
5840,8480,6080,8520
5620,8500,5840,8480
5500,8500,5620,8500
5340,8560,5500,8500
5160,8540,5340,8560
4620,8520,4880,8520
4360,8480,4620,8520
4880,8520,5160,8540
4140,8440,4360,8480
3920,8460,4140,8440
3720,8380,3920,8460
3680,8160,3720,8380
3680,8160,3720,7940
3720,7720,3720,7940
3680,7580,3720,7720
3680,7580,3720,7440
3720,7440,3720,7300
3720,7160,3720,7300
3720,7160,3720,7020
3720,7020,3780,6900
3780,6900,4080,6940
4080,6940,4340,6980
4340,6980,4600,6980
4600,6980,4880,6980
4880,6980,5160,6980
5160,6980,5400,7000
5400,7000,5560,7020
5560,7020,5660,7080
5660,7080,5660,7280
5660,7280,5660,7440
5660,7440,5740,7520
5740,7520,5740,7600
5740,7600,5900,7600
5900,7600,6040,7540
6040,7540,6040,7320
6040,7320,6120,7200
6120,7200,6120,7040
6120,7040,6240,7000
6240,7000,6480,7060
6480,7060,6800,7060
6800,7060,7080,7080
7080,7080,7320,7100
7940,7100,7980,6920
7860,6860,7980,6920
7640,6860,7860,6860
7400,6840,7640,6860
7320,7100,7560,7120
7560,7120,7760,7120
7760,7120,7940,7100
7200,6820,7400,6840
7040,6820,7200,6820
6600,6840,6840,6840
6380,6800,6600,6840
6120,6800,6380,6800
5900,6840,6120,6800
5620,6820,5900,6840
5400,6800,5620,6820
5140,6800,5400,6800
4880,6780,5140,6800
4600,6760,4880,6780
4340,6760,4600,6760
4080,6760,4340,6760
3840,6740,4080,6760
3680,6720,3840,6740
3680,6720,3680,6560
3680,6560,3720,6400
3720,6400,3720,6200
3720,6200,3780,6000
3720,5780,3780,6000
3720,5580,3720,5780
3720,5360,3720,5580
3720,5360,3840,5240
3840,5240,4200,5260
4200,5260,4600,5280
4600,5280,4880,5280
4880,5280,5140,5200
5140,5200,5220,5100
5220,5100,5280,4900
5280,4900,5340,4840
5340,4840,5720,4880
6120,4880,6480,4860
6880,4840,7200,4860
6480,4860,6880,4840
7200,4860,7320,4860
7320,4860,7360,4740
7360,4600,7440,4520
7360,4600,7360,4740
7440,4520,7640,4520
7640,4520,7800,4480
7800,4480,7800,4280
7800,4280,7800,4040
7800,4040,7800,3780
7800,3560,7800,3780
7800,3560,7860,3440
7860,3440,8060,3460
8060,3460,8160,3340
8160,3340,8160,3140
8160,3140,8160,2960
8000,2900,8160,2960
7860,2900,8000,2900
7640,2940,7860,2900
7400,2980,7640,2940
7100,2980,7400,2980
6840,3000,7100,2980
5620,2980,5840,2980
5840,2980,6500,3000
6500,3000,6840,3000
5560,2780,5620,2980
5560,2780,5560,2580
5560,2580,5560,2380
5560,2140,5560,2380
5560,2140,5560,1900
5560,1900,5620,1660
5620,1660,5660,1460
5660,1460,5660,1300
5500,1260,5660,1300
5340,1260,5500,1260
4600,1220,4840,1240
4440,1220,4600,1220
4440,1080,4440,1220
4440,1080,4600,1020
5080,1260,5340,1260
4840,1240,5080,1260
4600,1020,4940,1020
4940,1020,5220,1020
5220,1020,5560,960
5560,960,5660,860
5660,740,5660,860
5280,740,5660,740
4940,780,5280,740
4660,760,4940,780
4500,700,4660,760
4500,520,4500,700
4500,520,4700,460
4700,460,5080,440
5440,420,5740,420
5080,440,5440,420
5740,420,5840,360
5800,280,5840,360
5560,280,5800,280
4980,300,5280,320
4360,320,4660,300
4200,360,4360,320
5280,320,5560,280
4660,300,4980,300
4140,480,4200,360
4140,480,4140,640
4140,640,4200,780
4200,780,4200,980
4200,980,4220,1180
4220,1400,4220,1180
4220,1400,4260,1540
4260,1540,4500,1540
4500,1540,4700,1520
4700,1520,4980,1540
5280,1560,5400,1560
4980,1540,5280,1560
5400,1560,5400,1700
5400,1780,5400,1700
5340,1900,5400,1780
5340,2020,5340,1900
5340,2220,5340,2020
5340,2220,5340,2420
5340,2420,5340,2520
5080,2600,5220,2580
5220,2580,5340,2520
4900,2580,5080,2600
4700,2540,4900,2580
4500,2540,4700,2540
4220,2580,4340,2540
4200,2700,4220,2580
4340,2540,4500,2540
3980,2740,4200,2700
3840,2740,3980,2740
3780,2640,3840,2740
3780,2640,3780,2460
3780,2280,3780,2460
3620,2020,3780,2100
3780,2280,3780,2100
3360,2040,3620,2020
3080,2040,3360,2040
2840,2020,3080,2040
2740,1940,2840,2020
2740,1940,2800,1800
2800,1640,2800,1800
2800,1640,2800,1460
2800,1300,2800,1460
2700,1180,2800,1300
2480,1140,2700,1180
1580,1200,1720,1200
2240,1180,2480,1140
1960,1180,2240,1180
1720,1200,1960,1180
1500,1320,1580,1200
1500,1440,1500,1320
1500,1440,1760,1480
1760,1480,1940,1480
1940,1480,2140,1500
2140,1500,2320,1520
2400,1560,2400,1700
2280,1820,2380,1780
2320,1520,2400,1560
2380,1780,2400,1700
2080,1840,2280,1820
1720,1820,2080,1840
1420,1800,1720,1820
1280,1800,1420,1800
1240,1720,1280,1800
1240,1720,1240,1600
1240,1600,1280,1480
1280,1340,1280,1480
1180,1280,1280,1340
1000,1280,1180,1280
760,1280,1000,1280
360,1240,540,1260
180,1220,360,1240
540,1260,760,1280
180,1080,180,1220
180,1080,180,1000
180,1000,360,940
360,940,540,960
540,960,820,980
1100,980,1200,920
820,980,1100,980
6640,11860,6940,11920
5200,11280,5500,11280
4120,7330,4120,7230
4120,7230,4660,7250
4660,7250,4940,7250
4940,7250,5050,7340
5010,7400,5050,7340
4680,7380,5010,7400
4380,7370,4680,7380
4120,7330,4360,7370
4120,7670,4120,7760
4120,7670,4280,7650
4280,7650,4540,7660
4550,7660,4820,7680
4820,7680,4900,7730
4880,7800,4900,7730
4620,7820,4880,7800
4360,7790,4620,7820
4120,7760,4360,7790
6840,6840,7040,6820
5720,4880,6120,4880
1200,920,1340,810
1340,810,1520,790
1520,790,1770,800
2400,790,2600,750
2600,750,2640,520
2520,470,2640,520
2140,470,2520,470
1760,800,2090,800
2080,800,2400,790
1760,450,2140,470
1420,450,1760,450
1180,440,1420,450
900,480,1180,440
640,450,900,480
360,440,620,450
120,430,360,440
0,520,120,430
-20,780,0,520
-20,780,-20,1020
-20,1020,-20,1150
-20,1150,0,1300
0,1470,60,1530
0,1300,0,1470
60,1530,360,1530
360,1530,660,1520
660,1520,980,1520
980,1520,1040,1520
1040,1520,1070,1560
1070,1770,1070,1560
1070,1770,1100,2010
1070,2230,1100,2010
1070,2240,1180,2340
1180,2340,1580,2340
1580,2340,1940,2350
1940,2350,2440,2350
2440,2350,2560,2380
2560,2380,2600,2540
2810,2640,3140,2680
2600,2540,2810,2640
3140,2680,3230,2780
3230,2780,3260,2970
3230,3220,3260,2970
3200,3470,3230,3220
3200,3480,3210,3760
3210,3760,3210,4040
3200,4040,3230,4310
3210,4530,3230,4310
3210,4530,3230,4730
3230,4960,3230,4730
3230,4960,3260,5190
3170,5330,3260,5190
2920,5330,3170,5330
2660,5360,2920,5330
2420,5330,2660,5360
2200,5280,2400,5330
2020,5280,2200,5280
1840,5260,2020,5280
1660,5280,1840,5260
1500,5300,1660,5280
1360,5270,1500,5300
1200,5290,1340,5270
1070,5400,1200,5290
1040,5630,1070,5400
1000,5900,1040,5630
980,6170,1000,5900
980,6280,980,6170
980,6540,980,6280
980,6540,1040,6720
1040,6720,1360,6730
1360,6730,1760,6710
2110,6720,2420,6730
1760,6710,2110,6720
2420,6730,2640,6720
2640,6720,2970,6720
2970,6720,3160,6700
3160,6700,3240,6710
3240,6710,3260,6890
3260,7020,3260,6890
3230,7180,3260,7020
3230,7350,3230,7180
3210,7510,3230,7350
3210,7510,3210,7690
3210,7870,3210,7690
3210,7870,3210,7980
3200,8120,3210,7980
3200,8330,3200,8120
3160,8520,3200,8330
2460,11100,2480,11020
2200,11180,2460,11100
1260,11350,1600,11320
600,11430,930,11400
180,11340,620,11430
1600,11320,1910,11280
1910,11280,2200,11180
923.0029599285435,11398.99893503157,1264.002959928544,11351.99893503157

    The Little Probe - Data - level_lava.txt link

    # ./samples/99_genre_platformer/the_little_probe/data/level_lava.txt
100,10740,500,10780
500,10780,960,10760
960,10760,1340,10760
1380,10760,1820,10780
1820,10780,2240,10780
2280,10780,2740,10740
2740,10740,3000,10780
3000,10780,3140,11020
-520,8820,-480,9160
-520,8480,-520,8820
-520,8480,-480,8180
-480,8180,-200,8120
-200,8120,100,8220
100,8220,420,8240
420,8240,760,8260
760,8260,1140,8280
1140,8280,1500,8200
1500,8200,1880,8240
1880,8240,2240,8260
2240,8260,2320,8480
2320,8480,2380,8680
2240,8860,2380,8680
2240,9080,2240,8860
2240,9080,2320,9260
2320,9260,2480,9440
2480,9440,2600,9640
2480,9840,2600,9640
2400,10020,2480,9840
2240,10080,2400,10020
1960,10080,2240,10080
1720,10080,1960,10080
1460,10080,1720,10080
1180,10080,1420,10080
900,10080,1180,10080
640,10080,900,10080
640,10080,640,9900
60,10520,100,10740
40,10240,60,10520
40,10240,40,9960
40,9960,40,9680
40,9680,40,9360
40,9360,60,9080
60,9080,100,8860
100,8860,460,9040
460,9040,760,9220
760,9220,1140,9220
1140,9220,1720,9200
-660,11580,-600,11420
-660,11800,-660,11580
-660,12000,-660,11800
-660,12000,-600,12220
-600,12220,-600,12440
-600,12440,-600,12640
-600,11240,-260,11280
-260,11280,100,11240
9000,12360,9020,12400
9020,12620,9020,12400
9020,12840,9020,12620
9020,13060,9020,12840
9020,13060,9020,13240
9020,13240,9020,13420
9020,13420,9020,13600
9020,13600,9020,13780
8880,13900,9020,13780
8560,13800,8880,13900
8220,13780,8560,13800
7860,13760,8220,13780
7640,13780,7860,13760
7360,13800,7640,13780
7100,13800,7360,13800
6540,13760,6800,13780
6800,13780,7100,13800
6280,13760,6540,13760
5760,13760,6280,13760
5220,13780,5760,13760
4700,13760,5220,13780
4200,13740,4700,13760
3680,13720,4200,13740
3140,13700,3680,13720
2600,13680,3140,13700
2040,13940,2600,13680
1640,13940,2040,13940
1200,13960,1640,13940
840,14000,1200,13960
300,13960,840,14000
-200,13900,300,13960
-600,12840,-600,12640
-600,13140,-600,12840
-600,13140,-600,13420
-600,13700,-600,13420
-600,13700,-600,13820
-600,13820,-200,13900
-600,11240,-560,11000
-560,11000,-480,10840
-520,10660,-480,10840
-520,10660,-520,10480
-520,10480,-520,10300
-520,10260,-480,10080
-480,9880,-440,10060
-520,9680,-480,9880
-520,9680,-480,9400
-480,9400,-480,9160
1820,9880,2140,9800
1540,9880,1820,9880
1200,9920,1500,9880
900,9880,1200,9920
640,9900,840,9880
2380,8760,2800,8760
2800,8760,2840,8660
2840,8660,2840,8420
2840,8160,2840,8420
2800,7900,2840,8160
2800,7900,2800,7720
2800,7540,2800,7720
2800,7540,2800,7360
2700,7220,2800,7360
2400,7220,2700,7220
2080,7240,2400,7220
1760,7320,2080,7240
1380,7360,1720,7320
1040,7400,1340,7360
640,7400,1000,7420
300,7380,640,7400
0,7300,240,7380
-300,7180,-60,7300
-380,6860,-360,7180
-380,6880,-360,6700
-360,6700,-260,6540
-260,6540,0,6520
0,6520,240,6640
240,6640,460,6640
460,6640,500,6480
500,6260,500,6480
460,6060,500,6260
460,5860,460,6060
460,5860,500,5640
500,5640,540,5440
540,5440,580,5220
580,5220,580,5000
580,4960,580,4740
580,4740,960,4700
960,4700,1140,4760
1140,4760,1420,4740
1420,4740,1720,4700
1720,4700,2000,4740
2000,4740,2380,4760
2380,4760,2700,4800
1720,4600,1760,4300
1760,4300,2200,4340
2200,4340,2560,4340
2560,4340,2740,4340
2160,12580,2440,12400
1820,12840,2160,12580
1500,13080,1820,12840
1140,13340,1500,13080
1140,13340,1580,13220
2110,13080,2520,13000
2520,13000,2900,12800
1580,13220,2110,13080
2900,12800,3200,12680
3200,12680,3440,12640
3440,12640,3720,12460
3720,12460,4040,12320
4040,12320,4360,12200
4360,11940,4380,12180
4360,11700,4360,11940
4360,11700,4540,11500
4540,11500,4880,11540
6000,11660,6280,11640
5440,11600,5720,11610
5720,11610,6000,11660
6280,11640,6760,11720
6760,11720,7060,11780
7060,11780,7360,11810
7360,11810,7640,11840
7640,11840,8000,11830
8000,11830,8320,11850
8320,11850,8390,11800
8330,11760,8390,11800
8160,11760,8330,11760
7910,11750,8160,11760
7660,11740,7900,11750
7400,11730,7660,11740
7160,11680,7400,11730
7080,11570,7160,11680
7080,11570,7100,11350
7100,11350,7440,11280
7440,11280,7940,11280
7960,11280,8360,11280
5840,11540,6650,11170
4880,11540,5440,11600
3410,11830,3420,11300
3410,11260,3520,10920
3520,10590,3520,10920
3520,10590,3540,10260
3520,9900,3540,10240
3520,9900,3640,9590
3640,9570,4120,9590
4140,9590,4600,9680
4620,9680,5030,9730
5120,9750,5520,9800
5620,9820,6080,9800
6130,9810,6580,9820
6640,9820,6800,9700
6780,9400,6800,9700
6780,9400,6840,9140
6820,8860,6840,9120
6780,8600,6820,8830
6720,8350,6780,8570
6480,8340,6720,8320
6260,8400,6480,8340
6050,8580,6240,8400
5760,8630,6040,8590
5520,8690,5740,8630
5120,8690,5450,8700
4570,8670,5080,8690
4020,8610,4540,8670
3540,8480,4020,8610
3520,8230,3520,8480
3520,7930,3520,8230
3520,7930,3540,7630
3480,7320,3540,7610
3480,7280,3500,7010
3500,6980,3680,6850
3680,6850,4220,6840
4230,6840,4760,6850
4780,6850,5310,6860
5310,6860,5720,6940
5720,6940,5880,7250
5880,7250,5900,7520
100,11240,440,11300
440,11300,760,11330
1480,11280,1840,11230
2200,11130,2360,11090
1840,11230,2200,11130

    Genre Rpg Narrative link

    Choose Your Own Adventure - decision.rb link

    # ./samples/99_genre_rpg_narrative/choose_your_own_adventure/app/decision.rb
# Hey there! Welcome to Four Decisions. Here is how you
# create your decision tree. Remove =being and =end from the text to
# enable the game (just save the file). Change stuff and see what happens!

def game
  {
    starting_decision: :stormy_night,
    decisions: {
      stormy_night: {
        description: 'It was a dark and stormy night. (storyline located in decision.rb)',
        option_one: {
          description: 'Go to sleep.',
          decision: :nap
        },
        option_two: {
          description: 'Watch a movie.',
          decision: :movie
        },
        option_three: {
          description: 'Go outside.',
          decision: :go_outside
        },
        option_four: {
          description: 'Get a snack.',
          decision: :get_a_snack
        }
      },
      nap: {
        description: 'You took a nap. The end.',
        option_one: {
          description: 'Start over.',
          decision: :stormy_night
        }
      }
    }
  }
end

    Choose Your Own Adventure - main.rb link

    # ./samples/99_genre_rpg_narrative/choose_your_own_adventure/app/main.rb
=begin

 Reminders:

 - Hashes: Collection of unique keys and their corresponding values. The values can be found
   using their keys.

   In this sample app, the decisions needed for the game are stored in a hash. In fact, the
   decision.rb file contains hashes inside of other hashes!

   Each option is a key in the first hash, but also contains a hash (description and
   decision being its keys) as its value.
   Go into the decision.rb file and take a look before diving into the code below.

 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.md.

 - args.keyboard.key_down.KEY: Determines if a key is in the down state or pressed down.
   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.

 - String interpolation: uses #{} syntax; everything between the #{ and the } is evaluated
   as Ruby code, and the placeholder is replaced with its corresponding value or result.

=end

# This sample app provides users with a story and multiple decisions that they can choose to make.
# Users can make a decision using their keyboard, and the story will move forward based on user choices.

# The decisions available to users are stored in the decision.rb file.
# We must have access to it for the game to function properly.
GAME_FILE = 'app/decision.rb' # found in app folder

require GAME_FILE # require used to load another file, import class/method definitions

# Instructions are given using labels to users if they have not yet set up their story in the decision.rb file.
# Otherwise, the game is run.
def tick args
  if !args.state.loaded && !respond_to?(:game) # if game is not loaded and not responding to game symbol's method
    args.labels << [640, 370, 'Hey there! Welcome to Four Decisions.', 0, 1] # a welcome label is shown
    args.labels << [640, 340, 'Go to the file called decision.rb and tell me your story.', 0, 1]
  elsif respond_to?(:game) # otherwise, if responds to game
    args.state.loaded = true
    tick_game args # calls tick_game method, runs game
  end

  if args.state.tick_count.mod_zero? 60 # update every 60 frames
    t = args.gtk.ffi_file.mtime GAME_FILE # mtime returns modification time for named file
    if t != args.state.mtime
      args.state.mtime = t
      require GAME_FILE # require used to load file
      args.state.game_definition = nil # game definition and decision are empty
      args.state.decision_id = nil
    end
  end
end

# Runs methods needed for game to function properly
# Creates a rectangular border around the screen
def tick_game args
  defaults args
  args.borders << args.grid.rect
  render_decision args
  process_inputs args
end

# Sets default values and uses decision.rb file to define game and decision_id
# variable using the starting decision
def defaults args
  args.state.game_definition ||= game
  args.state.decision_id ||= args.state.game_definition[:starting_decision]
end

# Outputs the possible decision descriptions the user can choose onto the screen
# as well as what key to press on their keyboard to make their decision
def render_decision args
  decision = current_decision args
  # text is either the value of decision's description key or warning that no description exists
  args.labels << [640, 360, decision[:description] || "No definition found for #{args.state.decision_id}. Please update decision.rb.", 0, 1] # uses string interpolation

  # All decisions are stored in a hash
  # The descriptions output onto the screen are the values for the description keys of the hash.
  if decision[:option_one]
    args.labels << [10, 360, decision[:option_one][:description], 0, 0] # option one's description label
    args.labels << [10, 335, "(Press 'left' on the keyboard to select this decision)", -5, 0] # label of what key to press to select the decision
  end

  if decision[:option_two]
    args.labels << [1270, 360, decision[:option_two][:description], 0, 2] # option two's description
    args.labels << [1270, 335, "(Press 'right' on the keyboard to select this decision)", -5, 2]
  end

  if decision[:option_three]
    args.labels << [640, 45, decision[:option_three][:description], 0, 1] # option three's description
    args.labels << [640, 20, "(Press 'down' on the keyboard to select this decision)", -5, 1]
  end

  if decision[:option_four]
    args.labels << [640, 700, decision[:option_four][:description], 0, 1] # option four's description
    args.labels << [640, 675, "(Press 'up' on the keyboard to select this decision)", -5, 1]
  end
end

# Uses keyboard input from the user to make a decision
# Assigns the decision as the value of the decision_id variable
def process_inputs args
  decision = current_decision args # calls current_decision method

  if args.keyboard.key_down.left! && decision[:option_one] # if left key pressed and option one exists
    args.state.decision_id = decision[:option_one][:decision] # value of option one's decision hash key is set to decision_id
  end

  if args.keyboard.key_down.right! && decision[:option_two] # if right key pressed and option two exists
    args.state.decision_id = decision[:option_two][:decision] # value of option two's decision hash key is set to decision_id
  end

  if args.keyboard.key_down.down! && decision[:option_three] # if down key pressed and option three exists
    args.state.decision_id = decision[:option_three][:decision] # value of option three's decision hash key is set to decision_id
  end

  if args.keyboard.key_down.up! && decision[:option_four] # if up key pressed and option four exists
    args.state.decision_id = decision[:option_four][:decision] # value of option four's decision hash key is set to decision_id
  end
end

# Uses decision_id's value to keep track of current decision being made
def current_decision args
  args.state.game_definition[:decisions][args.state.decision_id] || {} # either has value or is empty
end

# Resets the game.
$gtk.reset

    Return Of Serenity - lowrez_simulator.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/lowrez_simulator.rb
###################################################################################
# YOU CAN PLAY AROUND WITH THE CODE BELOW, BUT USE CAUTION AS THIS IS WHAT EMULATES
# THE 64x64 CANVAS.
###################################################################################

TINY_RESOLUTION       = 64
TINY_SCALE            = 720.fdiv(TINY_RESOLUTION + 5)
CENTER_OFFSET         = 10
EMULATED_FONT_SIZE    = 20
EMULATED_FONT_X_ZERO  = 0
EMULATED_FONT_Y_ZERO  = 46

def tick args
  sprites = []
  labels = []
  borders = []
  solids = []
  mouse = emulate_lowrez_mouse args
  args.state.show_gridlines = false
  lowrez_tick args, sprites, labels, borders, solids, mouse
  render_gridlines_if_needed args
  render_mouse_crosshairs args, mouse
  emulate_lowrez_scene args, sprites, labels, borders, solids, mouse
end

def emulate_lowrez_mouse args
  args.state.new_entity_strict(:lowrez_mouse) do |m|
    m.x = args.mouse.x.idiv(TINY_SCALE) - CENTER_OFFSET.idiv(TINY_SCALE) - 1
    m.y = args.mouse.y.idiv(TINY_SCALE)
    if args.mouse.click
      m.click = [
        args.mouse.click.point.x.idiv(TINY_SCALE) - CENTER_OFFSET.idiv(TINY_SCALE) - 1,
        args.mouse.click.point.y.idiv(TINY_SCALE)
      ]
      m.down = m.click
    else
      m.click = nil
      m.down = nil
    end

    if args.mouse.up
      m.up = [
        args.mouse.up.point.x.idiv(TINY_SCALE) - CENTER_OFFSET.idiv(TINY_SCALE) - 1,
        args.mouse.up.point.y.idiv(TINY_SCALE)
      ]
    else
      m.up = nil
    end
  end
end

def render_mouse_crosshairs args, mouse
  return unless args.state.show_gridlines
  args.labels << [10, 25, "mouse: #{mouse.x} #{mouse.y}", 255, 255, 255]
end

def emulate_lowrez_scene args, sprites, labels, borders, solids, mouse
  args.render_target(:lowrez).transient!
  args.render_target(:lowrez).solids  << [0, 0, 1280, 720]
  args.render_target(:lowrez).sprites << sprites
  args.render_target(:lowrez).borders << borders
  args.render_target(:lowrez).solids  << solids
  args.outputs.primitives << labels.map do |l|
    as_label = l.label
    l.text.each_char.each_with_index.map do |char, i|
      [CENTER_OFFSET + EMULATED_FONT_X_ZERO + (as_label.x * TINY_SCALE) + i * 5 * TINY_SCALE,
       EMULATED_FONT_Y_ZERO + (as_label.y * TINY_SCALE), char,
       EMULATED_FONT_SIZE, 0, as_label.r, as_label.g, as_label.b, as_label.a, 'fonts/dragonruby-gtk-4x4.ttf'].label
    end
  end

  args.sprites    << [CENTER_OFFSET, 0, 1280 * TINY_SCALE, 720 * TINY_SCALE, :lowrez]
end

def render_gridlines_if_needed args
  if args.state.show_gridlines && args.static_lines.length == 0
    args.static_lines << 65.times.map do |i|
      [
        [CENTER_OFFSET + i * TINY_SCALE + 1,  0,
         CENTER_OFFSET + i * TINY_SCALE + 1,  720,                128, 128, 128],
        [CENTER_OFFSET + i * TINY_SCALE,      0,
         CENTER_OFFSET + i * TINY_SCALE,      720,                128, 128, 128],
        [CENTER_OFFSET,                       0 + i * TINY_SCALE,
         CENTER_OFFSET + 720,                 0 + i * TINY_SCALE, 128, 128, 128],
        [CENTER_OFFSET,                       1 + i * TINY_SCALE,
         CENTER_OFFSET + 720,                 1 + i * TINY_SCALE, 128, 128, 128]
      ]
    end
  elsif !args.state.show_gridlines
    args.static_lines.clear
  end
end

    Return Of Serenity - main.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/main.rb
require 'app/require.rb'

def defaults args
  args.outputs.background_color = [0, 0, 0]
  args.state.last_story_line_text ||= ""
  args.state.scene_history ||= []
  args.state.storyline_history ||= []
  args.state.word_delay ||= 8
  if args.state.tick_count == 0
    args.gtk.stop_music
    args.outputs.sounds << 'sounds/static-loop.ogg'
  end

  if args.state.last_story_line_text
    lines = args.state
                .last_story_line_text
                .gsub("-", "")
                .gsub("~", "")
                .wrapped_lines(50)

    args.outputs.labels << lines.map_with_index { |l, i| [690, 200 - (i * 25), l, 1, 0, 255, 255, 255] }
  elsif args.state.storyline_history[-1]
    lines = args.state
                .storyline_history[-1]
                .gsub("-", "")
                .gsub("~", "")
                .wrapped_lines(50)

    args.outputs.labels << lines.map_with_index { |l, i| [690, 200 - (i * 25), l, 1, 0, 255, 255, 255] }
  end

  return if args.state.current_scene
  set_scene(args, day_one_beginning(args))
end

def inputs_move_player args
  if args.state.scene_changed_at.elapsed_time > 5
    if args.keyboard.down  || args.keyboard.s || args.keyboard.j
      args.state.player.y -= 0.25
    elsif args.keyboard.up || args.keyboard.w || args.keyboard.k
      args.state.player.y += 0.25
    end

    if args.keyboard.left     || args.keyboard.a  || args.keyboard.h
      args.state.player.x -= 0.25
    elsif args.keyboard.right || args.keyboard.d  || args.keyboard.l
      args.state.player.x += 0.25
    end

    args.state.player.y = 60 if args.state.player.y > 63
    args.state.player.y =  0 if args.state.player.y < -3
    args.state.player.x = 60 if args.state.player.x > 63
    args.state.player.x =  0 if args.state.player.x < -3
  end
end

def null_or_empty? ary
  return true unless ary
  return true if ary.length == 0
  return false
end

def calc_storyline_hotspot args
  hotspots = args.state.storylines.find_all do |hs|
    args.state.player.inside_rect?(hs.shift_rect(-2, 0))
  end

  if !null_or_empty?(hotspots) && !args.state.inside_storyline_hotspot
    _, _, _, _, storyline = hotspots.first
    queue_storyline_text(args, storyline)
    args.state.inside_storyline_hotspot = true
  elsif null_or_empty?(hotspots)
    args.state.inside_storyline_hotspot = false

    args.state.storyline_queue_empty_at ||= args.state.tick_count
    args.state.is_storyline_dialog_active = false
    args.state.scene_storyline_queue.clear
  end
end

def calc_scenes args
  hotspots = args.state.scenes.find_all do |hs|
    args.state.player.inside_rect?(hs.shift_rect(-2, 0))
  end

  if !null_or_empty?(hotspots) && !args.state.inside_scene_hotspot
    _, _, _, _, scene_method_or_hash = hotspots.first
    if scene_method_or_hash.is_a? Symbol
      set_scene(args, send(scene_method_or_hash, args))
      args.state.last_hotspot_scene = scene_method_or_hash
      args.state.scene_history << scene_method_or_hash
    else
      set_scene(args, scene_method_or_hash)
    end
    args.state.inside_scene_hotspot = true
  elsif null_or_empty?(hotspots)
    args.state.inside_scene_hotspot = false
  end
end

def null_or_whitespace? word
  return true if !word
  return true if word.strip.length == 0
  return false
end

def calc_storyline_presentation args
  return unless args.state.tick_count > args.state.next_storyline
  return unless args.state.scene_storyline_queue
  next_storyline = args.state.scene_storyline_queue.shift
  if null_or_whitespace? next_storyline
    args.state.storyline_queue_empty_at ||= args.state.tick_count
    args.state.is_storyline_dialog_active = false
    return
  end
  args.state.storyline_to_show = next_storyline
  args.state.is_storyline_dialog_active = true
  args.state.storyline_queue_empty_at = nil
  if next_storyline.end_with?(".") || next_storyline.end_with?("!") || next_storyline.end_with?("?") || next_storyline.end_with?("\"")
    args.state.next_storyline += 60
  elsif next_storyline.end_with?(",")
    args.state.next_storyline += 50
  elsif next_storyline.end_with?(":")
    args.state.next_storyline += 60
  else
    default_word_delay = 13 + args.state.word_delay - 8
    if next_storyline.gsub("-", "").gsub("~", "").length <= 4
      default_word_delay = 11 + args.state.word_delay - 8
    end
    number_of_syllabals = next_storyline.length - next_storyline.gsub("-", "").length
    args.state.next_storyline += default_word_delay + number_of_syllabals * (args.state.word_delay + 1)
  end
end

def inputs_reload_current_scene args
  return
  if args.inputs.keyboard.key_down.r!
    reload_current_scene
  end
end

def inputs_dismiss_current_storyline args
  if args.inputs.keyboard.key_down.x!
    args.state.scene_storyline_queue.clear
  end
end

def inputs_restart_game args
  if args.inputs.keyboard.exclamation_point
    args.gtk.reset_state
  end
end

def inputs_change_word_delay args
  if args.inputs.keyboard.key_down.plus || args.inputs.keyboard.key_down.equal_sign
    args.state.word_delay -= 2
    if args.state.word_delay < 0
      args.state.word_delay = 0
      # queue_storyline_text args, "Text speed at MAXIMUM. Geez, how fast do you read?"
    else
      # queue_storyline_text args, "Text speed INCREASED."
    end
  end

  if args.inputs.keyboard.key_down.hyphen || args.inputs.keyboard.key_down.underscore
    args.state.word_delay += 2
    # queue_storyline_text args, "Text speed DECREASED."
  end
end

def multiple_lines args, x, y, texts, size = 0, minimum_alpha = nil
  texts.each_with_index.map do |t, i|
    [x, y - i * (25 + size * 2), t, size, 0, 255, 255, 255, adornments_alpha(args, 255, minimum_alpha)]
  end
end

def lowrez_tick args, lowrez_sprites, lowrez_labels, lowrez_borders, lowrez_solids, lowrez_mouse
  # args.state.show_gridlines = true
  defaults args
  render_current_scene args, lowrez_sprites, lowrez_labels, lowrez_solids
  render_controller args, lowrez_borders
  lowrez_solids << [0, 0, 64, 64, 0, 0, 0]
  calc_storyline_presentation args
  calc_scenes args
  calc_storyline_hotspot args
  inputs_move_player args
  inputs_print_mouse_rect args, lowrez_mouse
  inputs_reload_current_scene args
  inputs_dismiss_current_storyline args
  inputs_change_word_delay args
  inputs_restart_game args
end

def render_controller args, lowrez_borders
  args.state.up_button    = [85, 40, 15, 15, 255, 255, 255]
  args.state.down_button  = [85, 20, 15, 15, 255, 255, 255]
  args.state.left_button  = [65, 20, 15, 15, 255, 255, 255]
  args.state.right_button = [105, 20, 15, 15, 255, 255, 255]
  lowrez_borders << args.state.up_button
  lowrez_borders << args.state.down_button
  lowrez_borders << args.state.left_button
  lowrez_borders << args.state.right_button
end

def inputs_print_mouse_rect args, lowrez_mouse
  if lowrez_mouse.up
    args.state.mouse_held = false
  elsif lowrez_mouse.click
    mouse_rect = [lowrez_mouse.x, lowrez_mouse.y, 1, 1]
    if args.state.up_button.intersect_rect? mouse_rect
      args.state.player.y += 1
    end

    if args.state.down_button.intersect_rect? mouse_rect
      args.state.player.y -= 1
    end

    if args.state.left_button.intersect_rect? mouse_rect
      args.state.player.x -= 1
    end

    if args.state.right_button.intersect_rect? mouse_rect
      args.state.player.x += 1
    end
    args.state.mouse_held = true
  elsif args.state.mouse_held
    mouse_rect = [lowrez_mouse.x, lowrez_mouse.y, 1, 1]
    if args.state.up_button.intersect_rect? mouse_rect
      args.state.player.y += 0.25
    end

    if args.state.down_button.intersect_rect? mouse_rect
      args.state.player.y -= 0.25
    end

    if args.state.left_button.intersect_rect? mouse_rect
      args.state.player.x -= 0.25
    end

    if args.state.right_button.intersect_rect? mouse_rect
      args.state.player.x += 0.25
    end
  end

  if lowrez_mouse.click
    dx = lowrez_mouse.click.x - args.state.previous_mouse_click.x
    dy = lowrez_mouse.click.y - args.state.previous_mouse_click.y
    x, y, w, h = args.state.previous_mouse_click.x, args.state.previous_mouse_click.y, dx, dy
    puts "x #{lowrez_mouse.click.x}, y: #{lowrez_mouse.click.y}"
    if args.state.previous_mouse_click

      if dx < 0 && dx < 0
        x = x + w
        w = w.abs
        y = y + h
        h = h.abs
      end

      w += 1
      h += 1

      args.state.previous_mouse_click = nil
    else
      args.state.previous_mouse_click = lowrez_mouse.click
      square_x, square_y = lowrez_mouse.click
    end
  end
end

def try_centering! word
  word ||= ""
  just_word = word.gsub("-", "").gsub(",", "").gsub(".", "").gsub("'", "").gsub('""', "\"-\"")
  return word if just_word.strip.length == 0
  return word if just_word.include? "~"
  return "~#{word}" if just_word.length <= 2
  if just_word.length.mod_zero? 2
    center_index = just_word.length.idiv(2) - 1
  else
    center_index = (just_word.length - 1).idiv(2)
  end
  return "#{word[0..center_index - 1]}~#{word[center_index]}#{word[center_index + 1..-1]}"
end

def queue_storyline args, scene
  queue_storyline_text args, scene[:storyline]
end

def queue_storyline_text args, text
  args.state.last_story_line_text = text
  args.state.storyline_history << text if text
  words = (text || "").split(" ")
  words = words.map { |w| try_centering! w }
  args.state.scene_storyline_queue = words
  if args.state.scene_storyline_queue.length != 0
    args.state.scene_storyline_queue.unshift "~$--"
    args.state.storyline_to_show = "~."
  else
    args.state.storyline_to_show = ""
  end
  args.state.scene_storyline_queue << ""
  args.state.next_storyline = args.state.tick_count
end

def set_scene args, scene
  args.state.current_scene = scene
  args.state.background = scene[:background] ||  'sprites/todo.png'
  args.state.scene_fade = scene[:fade] || 0
  args.state.scenes = (scene[:scenes] || []).reject { |s| !s }
  args.state.scene_render_override = scene[:render_override]
  args.state.storylines = (scene[:storylines] || []).reject { |s| !s }
  args.state.scene_changed_at = args.state.tick_count
  if scene[:player]
    args.state.player = scene[:player]
  end
  args.state.inside_scene_hotspot = false
  args.state.inside_storyline_hotspot = false
  queue_storyline args, scene
end

def replay_storyline_rect
  [26, -1, 7, 4]
end

def labels_for_word word
  left_side_of_word = ""
  center_letter = ""
  right_side_of_word = ""

  if word[0] == "~"
    left_side_of_word = ""
    center_letter = word[1]
    right_side_of_word = word[2..-1]
  elsif word.length > 0
    left_side_of_word, right_side_of_word = word.split("~")
    center_letter = right_side_of_word[0]
    right_side_of_word = right_side_of_word[1..-1]
  end

  right_side_of_word = right_side_of_word.gsub("-", "")

  {
    left:   [29 - left_side_of_word.length * 4 - 1 * left_side_of_word.length, 2, left_side_of_word],
    center: [29, 2, center_letter, 255, 0, 0],
    right:  [34, 2, right_side_of_word]
  }
end

def render_scenes args, lowrez_sprites
  lowrez_sprites << args.state.scenes.flat_map do |hs|
    hotspot_square args, hs.x, hs.y, hs.w, hs.h
  end
end

def render_storylines args, lowrez_sprites
  lowrez_sprites << args.state.storylines.flat_map do |hs|
    hotspot_square args, hs.x, hs.y, hs.w, hs.h
  end
end

def adornments_alpha args, target_alpha = nil, minimum_alpha = nil
  return (minimum_alpha || 80) unless args.state.storyline_queue_empty_at
  target_alpha ||= 255
  target_alpha * args.state.storyline_queue_empty_at.ease(60)
end

def hotspot_square args, x, y, w, h
  if w >= 3 && h >= 3
    [
      [x + w.idiv(2) + 1, y, w.idiv(2), h, 'sprites/label-background.png', 0, adornments_alpha(args, 50), 23, 23, 23],
      [x, y, w.idiv(2), h, 'sprites/label-background.png', 0, adornments_alpha(args, 100), 223, 223, 223],
      [x + 1, y + 1, w - 2, h - 2, 'sprites/label-background.png', 0, adornments_alpha(args, 200), 40, 140, 40],
    ]
  else
    [
      [x, y, w, h, 'sprites/label-background.png', 0, adornments_alpha(args, 200), 0, 140, 0],
    ]
  end
end

def render_storyline_dialog args, lowrez_labels, lowrez_sprites
  return unless args.state.is_storyline_dialog_active
  return unless args.state.storyline_to_show
  labels = labels_for_word args.state.storyline_to_show
  if true # high rez version
    scale = 8.88
    offset = 45
    size = 25
    args.outputs.labels << [offset + labels[:left].x.-(1) * scale,
                            labels[:left].y * TINY_SCALE + 55,
                            labels[:left].text, size, 0, 0, 0, 0, 255,
                            'fonts/manaspc.ttf']
    center_text = labels[:center].text
    center_text = "|" if center_text == "$"
    args.outputs.labels << [offset + labels[:center].x * scale,
                            labels[:center].y * TINY_SCALE + 55,
                            center_text, size, 0, 255, 0, 0, 255,
                            'fonts/manaspc.ttf']
    args.outputs.labels << [offset + labels[:right].x * scale,
                            labels[:right].y * TINY_SCALE + 55,
                            labels[:right].text, size, 0, 0, 0, 0, 255,
                            'fonts/manaspc.ttf']
  else
    lowrez_labels << labels[:left]
    lowrez_labels << labels[:center]
    lowrez_labels << labels[:right]
  end
  args.state.is_storyline_dialog_active = true
  render_player args, lowrez_sprites
  lowrez_sprites <<  [0, 0, 64, 8, 'sprites/label-background.png']
end

def render_player args, lowrez_sprites
  lowrez_sprites << player_md_down(args, *args.state.player)
end

def render_adornments args, lowrez_sprites
  render_scenes args, lowrez_sprites
  render_storylines args, lowrez_sprites
  return if args.state.is_storyline_dialog_active
  lowrez_sprites << player_md_down(args, *args.state.player)
end

def global_alpha_percentage args, max_alpha = 255
  return 255 unless args.state.scene_changed_at
  return 255 unless args.state.scene_fade
  return 255 unless args.state.scene_fade > 0
  return max_alpha * args.state.scene_changed_at.ease(args.state.scene_fade)
end

def render_current_scene args, lowrez_sprites, lowrez_labels, lowrez_solids
  lowrez_sprites << [0, 0, 64, 64, args.state.background, 0, (global_alpha_percentage args)]
  if args.state.scene_render_override
    send args.state.scene_render_override, args, lowrez_sprites, lowrez_labels, lowrez_solids
  end
  storyline_to_show = args.state.storyline_to_show || ""
  render_adornments args, lowrez_sprites
  render_storyline_dialog args, lowrez_labels, lowrez_sprites

  if args.state.background == 'sprites/tribute-game-over.png'
    lowrez_sprites << [0, 0, 64, 11, 'sprites/label-background.png', 0, adornments_alpha(args, 200), 0, 0, 0]
    lowrez_labels << [9, 6, 'Return of', 255, 255, 255]
    lowrez_labels << [9, 1, ' Serenity', 255, 255, 255]
    if !args.state.ended
      args.gtk.stop_music
      args.outputs.sounds << 'sounds/music-loop.ogg'
      args.state.ended = true
    end
  end
end

def player_md_right args, x, y
  [x, y, 4, 11, 'sprites/player-right.png', 0, (global_alpha_percentage args)]
end

def player_md_left args, x, y
  [x, y, 4, 11, 'sprites/player-left.png', 0, (global_alpha_percentage args)]
end

def player_md_up args, x, y
  [x, y, 4, 11, 'sprites/player-up.png', 0, (global_alpha_percentage args)]
end

def player_md_down args, x, y
  [x, y, 4, 11, 'sprites/player-down.png', 0, (global_alpha_percentage args)]
end

def player_sm args, x, y
  [x, y, 3, 7, 'sprites/player-zoomed-out.png', 0, (global_alpha_percentage args)]
end

def player_xs args, x, y
  [x, y, 1, 4, 'sprites/player-zoomed-out.png', 0, (global_alpha_percentage args)]
end

    Return Of Serenity - require.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/require.rb
require 'app/lowrez_simulator.rb'
require 'app/storyline_day_one.rb'
require 'app/storyline_blinking_light.rb'
require 'app/storyline_serenity_introduction.rb'
require 'app/storyline_speed_of_light.rb'
require 'app/storyline_serenity_alive.rb'
require 'app/storyline_serenity_bio.rb'
require 'app/storyline_anka.rb'
require 'app/storyline_final_message.rb'
require 'app/storyline_final_decision.rb'
require 'app/storyline.rb'

    Return Of Serenity - storyline.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline.rb
def hotspot_top
  [4, 61, 56, 3]
end

def hotspot_bottom
  [4, 0, 56, 3]
end

def hotspot_top_right
  [62, 35, 3, 25]
end

def hotspot_bottom_right
  [62, 0, 3, 25]
end

def storyline_history_include? args, text
  args.state.storyline_history.any? { |s| s.gsub("-", "").gsub(" ", "").include? text.gsub("-", "").gsub(" ", "") }
end

def blinking_light_side_of_home_render args, lowrez_sprites, lowrez_labels, lowrez_solids
  lowrez_sprites << [48, 44, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [49, 45, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [50, 46, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
end

def blinking_light_mountain_pass_render args, lowrez_sprites, lowrez_labels, lowrez_solids
  lowrez_sprites << [18, 47, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [19, 48, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [20, 49, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
end

def blinking_light_path_to_observatory_render args, lowrez_sprites, lowrez_labels, lowrez_solids
  lowrez_sprites << [0, 26, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [1, 27, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [2, 28, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
end

def blinking_light_observatory_render args, lowrez_sprites, lowrez_labels, lowrez_solids
  lowrez_sprites << [23, 59, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [24, 60, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [25, 61, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
end

def blinking_light_inside_observatory_render args, lowrez_sprites, lowrez_labels, lowrez_solids
  lowrez_sprites << [30, 30, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [31, 31, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
  lowrez_sprites << [32, 32, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
end

def decision_graph context_message, context_action, context_result_one, context_result_two, context_result_three = [], context_result_four = []
  result_one_scene, result_one_label, result_one_text = context_result_one
  result_two_scene, result_two_label, result_two_text = context_result_two
  result_three_scene, result_three_label, result_three_text = context_result_three
  result_four_scene, result_four_label, result_four_text = context_result_four

  top_level_hash = {
    background: 'sprites/decision.png',
    fade: 60,
    player: [20, 36],
    storylines: [ ],
    scenes: [ ]
  }

  confirmation_result_one_hash = {
    background: 'sprites/decision.png',
    scenes: [ ],
    storylines: [ ]
  }

  confirmation_result_two_hash = {
    background: 'sprites/decision.png',
    scenes: [ ],
    storylines: [ ]
  }

  confirmation_result_three_hash = {
    background: 'sprites/decision.png',
    scenes: [ ],
    storylines: [ ]
  }

  confirmation_result_four_hash = {
    background: 'sprites/decision.png',
    scenes: [ ],
    storylines: [ ]
  }

  top_level_hash[:storylines] << [ 5, 35, 4, 4, context_message]
  top_level_hash[:storylines] << [20, 35, 4, 4, context_action]

  confirmation_result_one_hash[:scenes]       << [20, 35, 4, 4, top_level_hash]
  confirmation_result_one_hash[:scenes]       << [60, 50, 4, 4, result_one_scene]
  confirmation_result_one_hash[:storylines]   << [40, 50, 4, 4, "#{result_one_label}: \"#{result_one_text}\""]
  confirmation_result_one_hash[:scenes]       << [40, 40, 4, 4, confirmation_result_four_hash] if result_four_scene
  confirmation_result_one_hash[:scenes]       << [40, 30, 4, 4, confirmation_result_three_hash] if result_three_scene
  confirmation_result_one_hash[:scenes]       << [40, 20, 4, 4, confirmation_result_two_hash]

  confirmation_result_two_hash[:scenes]       << [20, 35, 4, 4, top_level_hash]
  confirmation_result_two_hash[:scenes]       << [40, 50, 4, 4, confirmation_result_one_hash]
  confirmation_result_two_hash[:scenes]       << [40, 40, 4, 4, confirmation_result_four_hash] if result_four_scene
  confirmation_result_two_hash[:scenes]       << [40, 30, 4, 4, confirmation_result_three_hash] if result_three_scene
  confirmation_result_two_hash[:scenes]       << [60, 20, 4, 4, result_two_scene]
  confirmation_result_two_hash[:storylines]   << [40, 20, 4, 4, "#{result_two_label}: \"#{result_two_text}\""]

  confirmation_result_three_hash[:scenes]     << [20, 35, 4, 4, top_level_hash]
  confirmation_result_three_hash[:scenes]     << [40, 50, 4, 4, confirmation_result_one_hash]
  confirmation_result_three_hash[:scenes]     << [40, 40, 4, 4, confirmation_result_four_hash]
  confirmation_result_three_hash[:scenes]     << [60, 30, 4, 4, result_three_scene]
  confirmation_result_three_hash[:storylines] << [40, 30, 4, 4, "#{result_three_label}: \"#{result_three_text}\""]
  confirmation_result_three_hash[:scenes]     << [40, 20, 4, 4, confirmation_result_two_hash]

  confirmation_result_four_hash[:scenes]      << [20, 35, 4, 4, top_level_hash]
  confirmation_result_four_hash[:scenes]      << [40, 50, 4, 4, confirmation_result_one_hash]
  confirmation_result_four_hash[:scenes]      << [60, 40, 4, 4, result_four_scene]
  confirmation_result_four_hash[:storylines]  << [40, 40, 4, 4, "#{result_four_label}: \"#{result_four_text}\""]
  confirmation_result_four_hash[:scenes]      << [40, 30, 4, 4, confirmation_result_three_hash]
  confirmation_result_four_hash[:scenes]      << [40, 20, 4, 4, confirmation_result_two_hash]

  top_level_hash[:scenes]     << [40, 50, 4, 4, confirmation_result_one_hash]
  top_level_hash[:scenes]     << [40, 40, 4, 4, confirmation_result_four_hash] if result_four_scene
  top_level_hash[:scenes]     << [40, 30, 4, 4, confirmation_result_three_hash] if result_three_scene
  top_level_hash[:scenes]     << [40, 20, 4, 4, confirmation_result_two_hash]

  top_level_hash
end

def ship_control_hotspot offset_x, offset_y, a, b, c, d
  results = []
  results << [ 6 + offset_x, 0 + offset_y, 4, 4, a]  if a
  results << [ 1 + offset_x, 5 + offset_y, 4, 4, b]  if b
  results << [ 6 + offset_x, 5 + offset_y, 4, 4, c]  if c
  results << [ 11 + offset_x, 5 + offset_y, 4, 4, d] if d
  results
end

def reload_current_scene
  if $gtk.args.state.last_hotspot_scene
    set_scene $gtk.args, send($gtk.args.state.last_hotspot_scene, $gtk.args)
    tick $gtk.args
  elsif respond_to? :set_scene
    set_scene $gtk.args, (replied_to_serenity_alive_firmly $gtk.args)
    tick $gtk.args
  end
  $gtk.console.close
end

    Return Of Serenity - storyline_anka.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_anka.rb
def anka_inside_room args
  {
    background: 'sprites/inside-home.png',
    player: [34, 35],
    storylines: [
      [34, 34, 4, 4, "Ahhhh!!! Oh god, it was just- a nightmare."],
    ],
    scenes: [
      [32, -1, 8, 3, :anka_observatory]
    ]
  }
end

def anka_observatory args
  {
    background: 'sprites/inside-observatory.png',
    fade: 60,
    player: [51, 12],
    storylines: [
      [50, 10, 4, 4,   "Breathe, Hiro. Just see what's there... everything--- will- be okay."]
    ],
    scenes: [
      [30, 18, 5, 12, :anka_inside_mainframe]
    ],
    render_override: :blinking_light_inside_observatory_render
  }
end

def anka_inside_mainframe args
  {
    player: [32, 4],
    background: 'sprites/mainframe.png',
    fade: 60,
    storylines: [
      [22, 45, 17, 4, (anka_last_reply args)],
      [45, 45,  4, 4, (anka_current_reply args)],
    ],
    scenes: [
      [*hotspot_top_right, :reply_to_anka]
    ]
  }
end

def reply_to_anka args
  decision_graph anka_current_reply(args),
                 "Matthew's-- wife is doing-- well. What's-- even-- better-- is that he's-- a dad, and he didn't-- even-- know it. Should- I- leave- out the part about-- the crew- being-- in hibernation-- for 20-- years? They- should- enter-- statis-- on a high- note... Right?",
                 [:replied_with_whole_truth, "Whole-- Truth--", anka_reply_whole_truth],
                 [:replied_with_half_truth, "Half-- Truth--", anka_reply_half_truth]
end

def anka_last_reply args
  if args.state.scene_history.include? :replied_to_serenity_alive_firmly
    return "Buffer--: #{serenity_alive_firm_reply.quote}"
  else
    return "Buffer--: #{serenity_alive_sugarcoated_reply.quote}"
  end
end

def anka_reply_whole_truth
  "Matthew's wife is doing-- very-- well. In fact, she was pregnant. Matthew-- is a dad. He has a son. But, I need- all-- of-- you-- to brace-- yourselves. You've-- been in statis-- for 20 years. A lot has changed. Most of Earth's-- population--- didn't-- survive. Tell- Matthew-- that I'm-- sorry he didn't-- get to see- his- son grow- up."
end

def anka_reply_half_truth
  "Matthew's--- wife- is doing-- very-- well. In fact, she was pregnant. Matthew is a dad! It's a boy! Tell- Matthew-- congrats-- for me. Hope-- to see- all of you- soon."
end

def replied_with_whole_truth args
  {
    background: 'sprites/inside-observatory.png',
    fade: 60,
    player: [32, 21],
    scenes: [[60, 0, 4, 32, :replied_to_anka_back_home]],
    storylines: [
      [30, 18, 5, 12, "Buffer-- has been set to: #{anka_reply_whole_truth.quote}"],
      [30, 10, 5, 4, "I- hope- I- did the right- thing- by laying-- it all- out- there."],
    ]
  }
end

def replied_with_half_truth args
  {
    background: 'sprites/inside-observatory.png',
    fade: 60,
    player: [32, 21],
    scenes: [[60, 0, 4, 32, :replied_to_anka_back_home]],
    storylines: [
      [30, 18, 5, 12, "Buffer-- has been set to: #{anka_reply_half_truth.quote}"],
      [30, 10, 5, 4, "I- hope- I- did the right- thing- by not giving-- them- the whole- truth."],
    ]
  }
end

def anka_current_reply args
  if args.state.scene_history.include? :replied_to_serenity_alive_firmly
    return "Hello. This is, Aanka. Sasha-- is still- trying-- to gather-- her wits about-- her, given- the gravity--- of your- last- reply. Thank- you- for being-- honest, and thank- you- for the help- with the ship- diagnostics. I was able-- to retrieve-- all of the navigation--- information---- after-- the battery--- swap. We- are ready-- to head back to Earth. Before-- we go- back- into-- statis, Matthew--- wanted-- to know- how his- wife- is doing. Please- reply-- as soon- as you can. He's-- not going-- to get- into-- the statis-- chamber-- until-- he knows- his wife is okay."
  else
    return "Hello. This is, Aanka. Thank- you for the help- with the ship's-- diagnostics. I was able-- to retrieve-- all of the navigation--- information--- after-- the battery-- swap. I- know-- that- you didn't-- tell- the whole truth- about-- how far we are from- Earth. Don't-- worry. I understand-- why you did it. We- are ready-- to head back to Earth. Before-- we go- back- into-- statis, Matthew--- wanted-- to know- how his- wife- is doing. Please- reply-- as soon- as you can. He's-- not going-- to get- into-- the statis-- chamber-- until-- he knows- his wife is okay."
  end
end

def replied_to_anka_back_home args
  if args.state.scene_history.include? :replied_with_whole_truth
    return {
      fade: 60,
      background: 'sprites/inside-home.png',
      player: [34, 4],
      storylines: [
        [34, 4, 4, 4, "I- hope-- this pit in my stomach-- is gone-- by tomorrow---."],
      ],
      scenes: [
        [30, 38, 12, 13, :final_message_sad],
      ]
    }
  else
    return {
      fade: 60,
      background: 'sprites/inside-home.png',
      player: [34, 4],
      storylines: [
        [34, 4, 4, 4, "I- get the feeling-- I'm going-- to sleep real well tonight--."],
      ],
      scenes: [
        [30, 38, 12, 13, :final_message_happy],
      ]
    }
  end
end

    Return Of Serenity - storyline_blinking_light.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_blinking_light.rb
def the_blinking_light args
  {
    fade: 60,
    background: 'sprites/side-of-home.png',
    player: [16, 13],
    scenes: [
      [52, 24, 11, 5, :blinking_light_mountain_pass],
    ],
    render_override: :blinking_light_side_of_home_render
  }
end

def blinking_light_mountain_pass args
  {
    background: 'sprites/mountain-pass-zoomed-out.png',
    player: [4, 4],
    scenes: [
      [18, 47, 5, 5, :blinking_light_path_to_observatory]
    ],
    render_override: :blinking_light_mountain_pass_render
  }
end

def blinking_light_path_to_observatory args
  {
    background: 'sprites/path-to-observatory.png',
    player: [60, 4],
    scenes: [
      [0, 26, 5, 5, :blinking_light_observatory]
    ],
    render_override: :blinking_light_path_to_observatory_render
  }
end

def blinking_light_observatory args
  {
    background: 'sprites/observatory.png',
    player: [60, 2],
    scenes: [
      [28, 39, 4, 10, :blinking_light_inside_observatory]
    ],
    render_override: :blinking_light_observatory_render
  }
end

def blinking_light_inside_observatory args
  {
    background: 'sprites/inside-observatory.png',
    player: [60, 2],
    storylines: [
      [50, 2, 4, 8,   "That's weird. I thought- this- mainframe-- was broken--."]
    ],
    scenes: [
      [30, 18, 5, 12, :blinking_light_inside_mainframe]
    ],
    render_override: :blinking_light_inside_observatory_render
  }
end

def blinking_light_inside_mainframe args
  {
    background: 'sprites/mainframe.png',
    fade: 60,
    player: [30, 4],
    scenes: [
      [62, 32, 4, 32, :reply_to_introduction]
    ],
    storylines: [
      [43, 43,  8, 8, "\"Mission-- control--, your- main- comm-- channels-- seem-- to be down. My apologies-- for- using-- this low- level-- exploit--. What's-- going-- on down there? We are ready-- for reentry--.\" Message--- Timestamp---: 4- hours-- 23--- minutes-- ago--."],
      [30, 30,  4, 4, "There's-- a low- level-- message-- here... NANI.T.F?"],
      [14, 10, 24, 4, "Oh interesting---. This transistor--- needed-- to be activated--- for the- mainframe-- to work."],
      [14, 20, 24, 4, "What the heck activated--- this thing- though?"]
    ]
  }
end

    Return Of Serenity - storyline_day_one.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_day_one.rb
def day_one_beginning args
  {
    background: 'sprites/side-of-home.png',
    player: [16, 13],
    scenes: [
      [0, 0, 64, 2, :day_one_infront_of_home],
    ],
    storylines: [
      [35, 10, 6, 6,  "Man. Hard to believe- that today- is the 20th--- anniversary-- of The Impact."]
    ]
  }
end

def day_one_infront_of_home args
  {
    background: 'sprites/front-of-home.png',
    player: [56, 23],
    scenes: [
      [43, 34, 10, 16, :day_one_home],
      [62, 0,  3, 40, :day_one_beginning],
      [0, 4, 3, 20, :day_one_ceremony]
    ],
    storylines: [
      [40, 20, 4, 4, "It looks like everyone- is already- at the rememberance-- ceremony."],
    ]
  }
end

def day_one_home args
  {
    background: 'sprites/inside-home.png',
    player: [34, 3],
    scenes: [
      [28, 0, 12, 2, :day_one_infront_of_home]
    ],
    storylines: [
      [
        38, 4, 4, 4, "My mansion- in all its glory! Okay yea, it's just a shipping- container-. Apparently-, it's nothing- like the luxuries- of the 2040's. But it's- all we have- in- this day and age. And it'll suffice."
      ],
      [
        28, 7, 4, 7,
        "Ahhh. My reading- couch. It's so comfortable--."
      ],
      [
        38, 21, 4, 4,
        "I'm- lucky- to have a computer--. I'm- one of the few people- with- the skills to put this- thing to good use."
      ],
      [
        45, 37, 4, 8,
        "This corner- of my home- is always- warmer-. It's cause of the ref~lected-- light- from the solar-- panels--, just on the other- side- of this wall. It's hard- to believe- there was o~nce-- an unlimited- amount- of electricity--."
      ],
      [
        32, 40, 8, 10,
        "This isn't- a good time- to sleep. I- should probably- head to the ceremony-."
      ],
      [
        25, 21, 5, 12,
        "Fifteen-- years- of computer-- science-- notes, neatly-- organized. Compiler--- Theory--, Linear--- Algebra---, Game-- Development---... Every-- subject-- imaginable--."
      ]
    ]
  }
end

def day_one_ceremony args
  {
    background: 'sprites/tribute.png',
    player: [57, 21],
    scenes: [
      [62, 0, 2, 40, :day_one_infront_of_home],
      [0, 24, 2, 40, :day_one_infront_of_library]
    ],
    storylines: [
      [53, 12, 3,  8,  "It's- been twenty- years since The Impact. Twenty- years, since Halley's-- Comet-- set Earth's- blue- sky on fire."],
      [45, 12, 3,  8,  "The space mission- sent to prevent- Earth's- total- destruction--, was a success. Only- 99.9%------ of the world's- population-- died-- that day. Hey, it's- better-- than 100%---- of humanity-- dying."],
      [20, 12, 23, 4, "The monument--- reads:---- Here- stands- the tribute-- to Space- Mission-- Serenity--- and- its- crew. You- have- given-- humanity--- a second-- chance."],
      [15, 12, 3,  8, "Rest- in- peace--- Matthew----, Sasha----, Aanka----"],
    ]
  }
end

def day_one_infront_of_library args
  {
    background: 'sprites/outside-library.png',
    player: [57, 21],
    scenes: [
      [62, 0, 2, 40, :day_one_ceremony],
      [49, 39, 6, 9, :day_one_library]
    ],
    storylines: [
      [50, 20, 4, 8,  "Shipping- containers-- as far- as the eye- can see. It's- rather- beautiful-- if you ask me. Even- though-- this- view- represents-- all- that's-- left- of humanity-."]
    ]
  }
end

def day_one_library args
  {
    background: 'sprites/library.png',
    player: [27, 4],
    scenes: [
      [0, 0, 64, 2, :end_day_one_infront_of_library]
    ],
    storylines: [
      [28, 22, 8, 4,  "I grew- up- in this library. I've- read every- book- here. My favorites-- were- of course-- anything- computer-- related."],
      [6, 32, 10, 6, "My favorite-- area--- of the library. The Science-- Section."]
    ]
  }
end

def end_day_one_infront_of_library args
  {
    background: 'sprites/outside-library.png',
    player: [51, 33],
    scenes: [
      [49, 39, 6, 9, :day_one_library],
      [62, 0, 2, 40, :end_day_one_monument],
    ],
    storylines: [
      [50, 27, 4, 4, "It's getting late. Better get some sleep."]
    ]
  }
end

def end_day_one_monument args
  {
    background: 'sprites/tribute.png',
    player: [2, 36],
    scenes: [
      [62, 0, 2, 40, :end_day_one_infront_of_home],
    ],
    storylines: [
      [50, 27, 4, 4, "It's getting late. Better get some sleep."],
    ]
  }
end

def end_day_one_infront_of_home args
  {
    background: 'sprites/front-of-home.png',
    player: [1, 17],
    scenes: [
      [43, 34, 10, 16, :end_day_one_home],
    ],
    storylines: [
      [20, 10, 4, 4, "It's getting late. Better get some sleep."],
    ]
  }
end

def end_day_one_home args
  {
    background: 'sprites/inside-home.png',
    player: [34, 3],
    scenes: [
      [32, 40, 8, 10, :end_day_one_dream],
    ],
    storylines: [
      [38, 4, 4, 4, "It's getting late. Better get some sleep."],
    ]
  }
end

def end_day_one_dream args
  {
    background: 'sprites/dream.png',
    fade: 60,
    player: [4, 4],
    scenes: [
      [62, 0, 2, 64, :explaining_the_special_power]
    ],
    storylines: [
      [10, 10, 4, 4, "Why- does this- moment-- always- haunt- my dreams?"],
      [20, 10, 4, 4, "This kid- reads these computer--- science--- books- nonstop-. What's- wrong with him?"],
      [30, 10, 4, 4, "There- is nothing-- wrong- with him. This behavior-- should be encouraged---! In fact-, I think- he's- special---. Have- you seen- him use- a computer---? It's-- almost-- as if he can- speak-- to it."]
    ]
  }
end

def explaining_the_special_power args
  {
    fade: 60,
    background: 'sprites/inside-home.png',
    player: [32, 30],
    scenes: [
      [
        38, 21, 4, 4, :explaining_the_special_power_inside_computer
      ],
    ]
  }
end

def explaining_the_special_power_inside_computer args
  {
    background: 'sprites/pc.png',
    fade: 60,
    player: [34, 4],
    scenes: [
      [0, 62, 64, 3, :the_blinking_light]
    ],
    storylines: [
      [14, 20, 24, 4, "So... I have a special-- power--. I don't-- need a mouse-, keyboard--, or even-- a monitor--- to control-- a computer--."],
      [14, 25, 24, 4, "I only-- pretend-- to use peripherals---, so as not- to freak- anyone--- out."],
      [14, 30, 24, 4, "Inside-- this silicon--- Universe---, is the only-- place I- feel- at peace."],
      [14, 35, 24, 4, "It's-- the only-- place where I don't-- feel alone."]
    ]
  }
end

    Return Of Serenity - storyline_final_decision.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_final_decision.rb
def final_decision_side_of_home args
  {
    fade: 120,
    background: 'sprites/side-of-home.png',
    player: [16, 13],
    scenes: [
      [52, 24, 11, 5, :final_decision_mountain_pass],
    ],
    render_override: :blinking_light_side_of_home_render,
    storylines: [
      [28, 13, 8, 4,  "Man. Hard to believe- that today- is the 21st--- anniversary-- of The Impact. Serenity--- will- be- home- soon."]
    ]
  }
end

def final_decision_mountain_pass args
  {
    background: 'sprites/mountain-pass-zoomed-out.png',
    player: [4, 4],
    scenes: [
      [18, 47, 5, 5, :final_decision_path_to_observatory]
    ],
    render_override: :blinking_light_mountain_pass_render
  }
end

def final_decision_path_to_observatory args
  {
    background: 'sprites/path-to-observatory.png',
    player: [60, 4],
    scenes: [
      [0, 26, 5, 5, :final_decision_observatory]
    ],
    render_override: :blinking_light_path_to_observatory_render
  }
end

def final_decision_observatory args
  {
    background: 'sprites/observatory.png',
    player: [60, 2],
    scenes: [
      [28, 39, 4, 10, :final_decision_inside_observatory]
    ],
    render_override: :blinking_light_observatory_render
  }
end

def final_decision_inside_observatory args
  {
    background: 'sprites/inside-observatory.png',
    player: [60, 2],
    storylines: [],
    scenes: [
      [30, 18, 5, 12, :final_decision_inside_mainframe]
    ],
    render_override: :blinking_light_inside_observatory_render
  }
end

def final_decision_inside_mainframe args
  {
    player: [32, 4],
    background: 'sprites/mainframe.png',
    storylines: [],
    scenes: [
      [*hotspot_top, :final_decision_ship_status],
    ]
  }
end

def final_decision_ship_status args
  {
    background: 'sprites/serenity.png',
    fade: 60,
    player: [30, 10],
    scenes: [
      [*hotspot_top_right, :final_decision]
    ],
    storylines: [
      [30,  8, 4, 4, "????"],
      *final_decision_ship_status_shared(args)
    ]
  }
end

def final_decision args
  decision_graph  "Stasis-- Chambers--: UNDERPOWERED, Life- forms-- will be terminated---- unless-- equilibrium----- is reached.",
                  "I CAN'T DO THIS... But... If-- I-- don't--- bring-- the- chambers--- to- equilibrium-----, they all die...",
                  [:final_decision_game_over_noone, "Kill--- Everyone---", "DO--- NOTHING?"],
                  [:final_decision_game_over_matthew, "Kill--- Sasha---", "KILL--- SASHA?"],
                  [:final_decision_game_over_anka, "Kill--- Aanka---", "KILL--- AANKA?"],
                  [:final_decision_game_over_sasha, "Kill--- Matthew---", "KILL--- MATTHEW?"]
end

def final_decision_game_over_noone args
  {
    background: 'sprites/tribute-game-over.png',
    player: [53, 14],
    fade: 600
  }
end

def final_decision_game_over_matthew args
  {
    background: 'sprites/tribute-game-over.png',
    player: [53, 14],
    fade: 600
  }
end

def final_decision_game_over_anka args
  {
    background: 'sprites/tribute-game-over.png',
    player: [53, 14],
    fade: 600
  }
end

def final_decision_game_over_sasha args
  {
    background: 'sprites/tribute-game-over.png',
    player: [53, 14],
    fade: 600
  }
end

def final_decision_ship_status_shared args
  [
    *ship_control_hotspot(24, 22,
                           "Stasis-- Chambers--: UNDERPOWERED, Life- forms-- will be terminated---- unless-- equilibrium----- is reached. WHAT?! NO!",
                           "Matthew's--- Chamber--: UNDER-- THREAT-- OF-- TERMINATION. WHAT?! NO!",
                           "Aanka's--- Chamber--: UNDER-- THREAT-- OF-- TERMINATION.  WHAT?! NO!",
                           "Sasha's--- Chamber--: UNDER-- THREAT-- OF-- TERMINATION. WHAT?! NO!"),
  ]
end

    Return Of Serenity - storyline_final_message.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_final_message.rb
def final_message_sad args
  {
    fade: 60,
    background: 'sprites/inside-home.png',
    player: [34, 35],
    storylines: [
      [34, 34, 4, 4, "Another-- sleepless-- night..."],
    ],
    scenes: [
      [32, -1, 8, 3, :final_message_observatory]
    ]
  }
end

def final_message_happy args
  {
    fade: 60,
    background: 'sprites/inside-home.png',
    player: [34, 35],
    storylines: [
      [34, 34, 4, 4, "Oh man, I slept like rock!"],
    ],
    scenes: [
      [32, -1, 8, 3, :final_message_observatory]
    ]
  }
end

def final_message_side_of_home args
  {
    fade: 60,
    background: 'sprites/side-of-home.png',
    player: [16, 13],
    scenes: [
      [52, 24, 11, 5, :final_message_mountain_pass],
    ],
    render_override: :blinking_light_side_of_home_render
  }
end

def final_message_mountain_pass args
  {
    background: 'sprites/mountain-pass-zoomed-out.png',
    player: [4, 4],
    scenes: [
      [18, 47, 5, 5, :final_message_path_to_observatory],
    ],
    storylines: [
      [18, 13, 5, 5, "Hnnnnnnnggg. My legs-- are still sore- from yesterday."]
    ],
    render_override: :blinking_light_mountain_pass_render
  }
end

def final_message_path_to_observatory args
  {
    background: 'sprites/path-to-observatory.png',
    player: [60, 4],
    scenes: [
      [0, 26, 5, 5, :final_message_observatory]
    ],
    storylines: [
      [22, 20, 10, 10, "This spot--, on the mountain, right here, it's-- perfect. This- is where- I'll-- yeet-- the person-- who is playing-- this- prank- on me."]
    ],
    render_override: :blinking_light_path_to_observatory_render
  }
end

def final_message_observatory args
  if args.state.scene_history.include? :replied_with_whole_truth
    return {
      background: 'sprites/inside-observatory.png',
      fade: 60,
      player: [51, 12],
      storylines: [
        [50, 10, 4, 4, "Here-- we- go..."]
      ],
      scenes: [
        [30, 18, 5, 12, :final_message_inside_mainframe]
      ],
      render_override: :blinking_light_inside_observatory_render
    }
  else
    return {
      background: 'sprites/inside-observatory.png',
      fade: 60,
      player: [51, 12],
      storylines: [
        [50, 10, 4, 4, "I feel like I'm-- walking-- on sunshine!"]
      ],
      scenes: [
        [30, 18, 5, 12, :final_message_inside_mainframe]
      ],
      render_override: :blinking_light_inside_observatory_render
    }
  end
end

def final_message_inside_mainframe args
  {
    player: [32, 4],
    background: 'sprites/mainframe.png',
    fade: 60,
    scenes: [[45, 45,  4, 4, :final_message_check_ship_status]]
  }
end

def final_message_check_ship_status args
  {
    background: 'sprites/mainframe.png',
    storylines: [
      [45, 45, 4, 4, (final_message_current args)],
    ],
    scenes: [
      [*hotspot_top, :final_message_ship_status],
    ]
  }
end

def final_message_ship_status args
  {
    background: 'sprites/serenity.png',
    fade: 60,
    player: [30, 10],
    scenes: [
      [30, 50, 4, 4, :final_message_ship_status_reviewed]
    ],
    storylines: [
      [30,  8, 4, 4, "Let me make- sure- everything--- looks good. It'll-- give me peace- of mind."],
      *final_message_ship_status_shared(args)
    ]
  }
end

def final_message_ship_status_reviewed args
  {
    background: 'sprites/serenity.png',
    fade: 60,
    scenes: [
      [*hotspot_bottom, :final_message_summary]
    ],
    storylines: [
      [0, 62, 62, 3, "Whew. Everyone-- is in their- chambers. The engines-- are roaring-- and Serenity-- is coming-- home."],
    ]
  }
end

def final_message_ship_status_shared args
  [
    *ship_control_hotspot( 0, 50,
                           "Stasis-- Chambers--: Online, All chambers-- are powered. Battery--- Allocation---: 3--- of-- 3--.",
                           "Matthew's--- Chamber--: OCCUPIED----",
                           "Aanka's--- Chamber--: OCCUPIED----",
                           "Sasha's--- Chamber--: OCCUPIED----"),
    *ship_control_hotspot(12, 35,
                          "Life- Support--: Not-- Needed---",
                          "O2--- Production---: OFF---",
                          "CO2--- Scrubbers---: OFF---",
                          "H2O--- Production---: OFF---"),
    *ship_control_hotspot(24, 20,
                          "Navigation: Offline---",
                          "Sensor: OFF---",
                          "Heads- Up- Display: DAMAGED---",
                          "Arithmetic--- Unit: DAMAGED----"),
    *ship_control_hotspot(36, 35,
                          "COMM: Underpowered----",
                          "Text: ON---",
                          "Audio: SEGFAULT---",
                          "Video: DAMAGED---"),
    *ship_control_hotspot(48, 50,
                          "Engine: Online, Coordinates--- Set- for Earth. Battery--- Allocation---: 3--- of-- 3---",
                          "Engine I: ON---",
                          "Engine II: ON---",
                          "Engine III: ON---")
  ]
end

def final_message_last_reply args
  if args.state.scene_history.include? :replied_with_whole_truth
    return "Buffer--: #{anka_reply_whole_truth.quote}"
  else
    return "Buffer--: #{anka_reply_half_truth.quote}"
  end
end

def final_message_current args
  if args.state.scene_history.include? :replied_with_whole_truth
    return "Hey... It's-- me Sasha. Aanka-- is trying-- her best to comfort-- Matthew. This- is the first- time- I've-- ever-- seen-- Matthew-- cry. We'll-- probably-- be in stasis-- by the time you get this message--. Thank- you- again-- for all your help. I look forward-- to meeting-- you in person."
  else
    return "Hey! It's-- me Sasha! LOL! Aanka-- and Matthew-- are dancing-- around-- like- goofballs--! They- are both- so adorable! Only-- this- tiny-- little-- genius-- can make-- a battle-- hardened-- general--- put- on a tiara-- and dance- around-- like a fairy-- princess-- XD------ Anyways, we are heading-- back into-- the chambers--. I hope our welcome-- home- parade-- has fireworks!"
  end
end

def final_message_summary args
  if args.state.scene_history.include? :replied_with_whole_truth
    return {
      background: 'sprites/inside-observatory.png',
      fade: 60,
      player: [31, 11],
      scenes: [[60, 0, 4, 32, :final_decision_side_of_home]],
      storylines: [
        [30, 10, 5, 4, "I can't-- imagine-- what they are feeling-- right now. But at least- they- know everything---, and we can- concentrate-- on rebuilding--- this world-- right- off the bat. I can't-- wait to see the future-- they'll-- help- build."],
      ]
    }
  else
    return {
      background: 'sprites/inside-observatory.png',
      fade: 60,
      player: [31, 11],
      scenes: [[60, 0, 4, 32, :final_decision_side_of_home]],
      storylines: [
        [30, 10, 5, 4, "They all sounded-- so happy. I know- they'll-- be in for a tough- dose- of reality--- when they- arrive. But- at least- they'll-- be around-- all- of us. We'll-- help them- cope."],
      ]
    }
  end
end

    Return Of Serenity - storyline_serenity_alive.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_serenity_alive.rb
def serenity_alive_side_of_home args
  {
    fade: 60,
    background: 'sprites/side-of-home.png',
    player: [16, 13],
    scenes: [
      [52, 24, 11, 5, :serenity_alive_mountain_pass],
    ],
    render_override: :blinking_light_side_of_home_render
  }
end

def serenity_alive_mountain_pass args
  {
    background: 'sprites/mountain-pass-zoomed-out.png',
    player: [4, 4],
    scenes: [
      [18, 47, 5, 5, :serenity_alive_path_to_observatory],
    ],
    storylines: [
      [18, 13, 5, 5, "Hnnnnnnnggg. My legs-- are still sore- from yesterday."]
    ],
    render_override: :blinking_light_mountain_pass_render
  }
end

def serenity_alive_path_to_observatory args
  {
    background: 'sprites/path-to-observatory.png',
    player: [60, 4],
    scenes: [
      [0, 26, 5, 5, :serenity_alive_observatory]
    ],
    storylines: [
      [22, 20, 10, 10, "This spot--, on the mountain, right here, it's-- perfect. This- is where- I'll-- yeet-- the person-- who is playing-- this- prank- on me."]
    ],
    render_override: :blinking_light_path_to_observatory_render
  }
end

def serenity_alive_observatory args
  {
    background: 'sprites/observatory.png',
    player: [60, 2],
    scenes: [
      [28, 39, 4, 10, :serenity_alive_inside_observatory]
    ],
    render_override: :blinking_light_observatory_render
  }
end

def serenity_alive_inside_observatory args
  {
    background: 'sprites/inside-observatory.png',
    player: [60, 2],
    storylines: [],
    scenes: [
      [30, 18, 5, 12, :serenity_alive_inside_mainframe]
    ],
    render_override: :blinking_light_inside_observatory_render
  }
end

def serenity_alive_inside_mainframe args
  {
    background: 'sprites/mainframe.png',
    fade: 60,
    player: [30, 4],
    scenes: [
      [*hotspot_top, :serenity_alive_ship_status],
    ],
    storylines: [
      [22, 45, 17, 4, (serenity_alive_last_reply args)],
      [45, 45,  4, 4, (serenity_alive_current_message args)],
    ]
  }
end

def serenity_alive_ship_status args
  {
    background: 'sprites/serenity.png',
    fade: 60,
    player: [30, 10],
    scenes: [
      [30, 50, 4, 4, :serenity_alive_ship_status_reviewed]
    ],
    storylines: [
      [30,  8, 4, 4, "Serenity? THE--- Mission-- Serenity?! How is that possible? They- are supposed-- to be dead."],
      [30, 10, 4, 4, "I... can't-- believe-- it. I- can access-- Serenity's-- computer? I- guess my \"superpower----\" isn't limited-- by proximity-- to- a machine--."],
      *serenity_alive_shared_ship_status(args)
    ]
  }
end

def serenity_alive_ship_status_reviewed args
  {
    background: 'sprites/serenity.png',
    fade: 60,
    scenes: [
      [*hotspot_bottom, :serenity_alive_time_to_reply]
    ],
    storylines: [
      [0, 62, 62, 3, "Okay. Reviewing-- everything--, it looks- like- I- can- take- the batteries--- from the Stasis--- Chambers--- and- Engine--- to keep- the crew-- alive-- and-- their-- location--- pinpointed---."],
    ]
  }
end

def serenity_alive_time_to_reply args
  decision_graph serenity_alive_current_message(args),
                  "Okay... time to deliver the bad news...",
                  [:replied_to_serenity_alive_firmly, "Firm-- Reply", serenity_alive_firm_reply],
                  [:replied_to_serenity_alive_kindly, "Sugar-- Coated---- Reply", serenity_alive_sugarcoated_reply]
end

def serenity_alive_shared_ship_status args
  [
    *ship_control_hotspot( 0, 50,
                           "Stasis-- Chambers--: Online, All chambers-- are powered. Battery--- Allocation---: 3--- of-- 3--, Hmmm. They don't-- need this to be powered-- right- now. Everyone-- is awake.",
                           nil,
                           nil,
                           nil),
    *ship_control_hotspot(12, 35,
                          "Life- Support--: Offline, Unable--- to- Sustain-- Life. Battery--- Allocation---: 0--- of-- 3---, Okay. That is definitely---- not a good thing.",
                          nil,
                          nil,
                          nil),
    *ship_control_hotspot(24, 20,
                          "Navigation: Offline, Unable--- to- Calculate--- Location. Battery--- Allocation---: 0--- of-- 3---, Whelp. No wonder-- Sasha-- can't-- get- any-- readings. Their- Navigation--- is completely--- offline.",
                          nil,
                          nil,
                          nil),
    *ship_control_hotspot(36, 35,
                          "COMM: Underpowered----, Limited--- to- Text-- Based-- COMM. Battery--- Allocation---: 1--- of-- 3---, It's-- lucky- that- their- COMM---- system was able to survive-- twenty-- years--. Just- barely-- it seems.",
                          nil,
                          nil,
                          nil),
    *ship_control_hotspot(48, 50,
                          "Engine: Online, Full- Control-- Available. Battery--- Allocation---: 3--- of-- 3---, Hmmm. No point of having an engine-- online--, if you don't- know- where you're-- going.",
                          nil,
                          nil,
                          nil)
  ]
end

def serenity_alive_firm_reply
  "Serenity, you are at a distance-- farther-- than- Neptune. All- of the ship's-- systems-- are failing. Please- move the batteries---- from- the Stasis-- Chambers-- over- to- Life-- Support--. I also-- need- you to move-- the batteries---- from- the Engines--- to your Navigation---- System."
end

def serenity_alive_sugarcoated_reply
  "So... you- are- a teeny--- tiny--- bit--- farther-- from Earth- than you think. And you have a teeny--- tiny--- problem-- with your ship. Please-- move the batteries--- from the Stasis--- Chambers--- over to Life--- Support---. I also need you to move the batteries--- from the Engines--- to your- Navigation--- System. Don't-- worry-- Sasha. I'll-- get y'all-- home."
end

def replied_to_serenity_alive_firmly args
  {
    background: 'sprites/inside-observatory.png',
    fade: 60,
    player: [32, 21],
    scenes: [
      [*hotspot_bottom_right, :serenity_alive_path_from_observatory]
    ],
    storylines: [
      [30, 18, 5, 12, "Buffer-- has been set to: #{serenity_alive_firm_reply.quote}"],
      *serenity_alive_reply_completed_shared_hotspots(args),
    ]
  }
end

def replied_to_serenity_alive_kindly args
  {
    background: 'sprites/inside-observatory.png',
    fade: 60,
    player: [32, 21],
    scenes: [
      [*hotspot_bottom_right, :serenity_alive_path_from_observatory]
    ],
    storylines: [
      [30, 18, 5, 12, "Buffer-- has been set to: #{serenity_alive_sugarcoated_reply.quote}"],
      *serenity_alive_reply_completed_shared_hotspots(args),
    ]
  }
end

def serenity_alive_path_from_observatory args
  {
    fade: 60,
    background: 'sprites/path-to-observatory.png',
    player: [4, 21],
    scenes: [
      [*hotspot_bottom_right, :serenity_bio_infront_of_home]
    ],
    storylines: [
      [22, 20, 10, 10, "I'm not sure what's-- worse. Waiting-- for Sasha's-- reply. Or jumping-- off- from- right- here."]
    ]
  }
end

def serenity_alive_reply_completed_shared_hotspots args
  [
    [30, 10, 5, 4, "I guess it wasn't-- a joke- after-- all."],
    [40, 10, 5, 4, "I barely-- remember--- the- history----- of the crew."],
    [50, 10, 5, 4, "It probably--- wouldn't-- hurt- to- refresh-- my memory--."]
  ]
end

def serenity_alive_last_reply args
  if args.state.scene_history.include? :replied_to_introduction_seriously
    return "Buffer--: \"Hello, Who- is sending-- this message--?\""
  else
    return "Buffer--: \"New- phone. Who dis?\""
  end
end

def serenity_alive_current_message args
  if args.state.scene_history.include? :replied_to_introduction_seriously
    "This- is Sasha. The Serenity--- crew-- is out of hibernation---- and ready-- for Earth reentry--. But, it seems like we are having-- trouble-- with our Navigation---- systems. Please advise.".quote
  else
    "LOL! Thanks for the laugh. I needed that. This- is Sasha. The Serenity--- crew-- is out of hibernation---- and ready-- for Earth reentry--. But, it seems like we are having-- trouble-- with our Navigation---- systems. Can you help me out- babe?".quote
  end
end

    Return Of Serenity - storyline_serenity_bio.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_serenity_bio.rb
def serenity_bio_infront_of_home args
  {
    fade: 60,
    background: 'sprites/front-of-home.png',
    player: [54, 23],
    scenes: [
      [44, 34, 8, 14, :serenity_bio_inside_home],
      [0, 3, 3, 22, :serenity_bio_library]
    ]
  }
end

def serenity_bio_inside_home args
  {
    background: 'sprites/inside-home.png',
    player: [34, 4],
    storylines: [
      [34, 4, 4, 4, "I'm--- completely--- exhausted."],
    ],
    scenes: [
      [30, 38, 12, 13, :serenity_bio_restless_sleep],
      [32, 0, 8, 3, :serenity_bio_infront_of_home],
    ]
  }
end

def serenity_bio_restless_sleep args
  {
    fade: 60,
    background: 'sprites/inside-home.png',
    storylines: [
      [32, 38, 10, 13, "I can't-- seem to sleep. I know nothing-- about the- crew-. Maybe- I- should- go read- up- on- them."],
    ],
    scenes: [
      [32, 0, 8, 3, :serenity_bio_infront_of_home],
    ]
  }
end

def serenity_bio_library args
  {
    background: 'sprites/library.png',
    fade: 60,
    player: [30, 7],
    scenes: [
      [21, 35, 3, 18, :serenity_bio_book]
    ]
  }
end

def serenity_bio_book args
  {
    background: 'sprites/book.png',
    fade: 60,
    player: [6, 52],
    storylines: [
      [ 4, 50, 56, 4, "The Title-- Reads: Never-- Forget-- Mission-- Serenity---"],

      [ 4, 38,  8, 8, "Name: Matthew--- R. Sex: Male--- Age-- at-- Departure: 36-----"],
      [14, 38, 46, 8, "Tribute-- Text: Matthew graduated-- Magna-- Cum-- Laude-- from MIT--- with-- a- PHD---- in Aero-- Nautical--- Engineering. He was immensely--- competitive, and had an insatiable---- thirst- for aerial-- battle. From the age of twenty, he remained-- undefeated--- in the Israeli-- Air- Force- \"Blue Flag\" combat-- exercises. By the age of 29--- he had already-- risen through- the ranks, and became-- the Lieutenant--- General--- of Lufwaffe. Matthew-- volenteered-- to- pilot-- Mission-- Serenity. To- this day, his wife- and son- are pillars-- of strength- for us. Rest- in Peace- Matthew, we are sorry-- that- news of the pregancy-- never-- reached- you. Please forgive us."],

      [4,  26,  8, 8, "Name: Aanka--- P. Sex: Female--- Age-- at-- Departure: 9-----"],
      [14, 26, 46, 8, "Tribute-- Text: Aanka--- gratuated--- Magna-- Cum- Laude-- from MIT, at- the- age- of eight, with a- PHD---- in Astro-- Physics. Her-- IQ--- was over 390, the highest-- ever- recorded--- IQ-- in- human-- history. She changed- the landscape-- of Physics-- with her efforts- in- unravelling--- the mysteries--- of- Dark- Matter--. Anka discovered-- the threat- of Halley's-- Comet-- collision--- with Earth. She spear headed-- the global-- effort-- for Misson-- Serenity. Her- multilingual--- address-- to- the world-- brought- us all hope."],

      [4,  14,  8, 8, "Name: Sasha--- N. Sex: Female--- Age-- at-- Departure: 29-----"],
      [14, 14, 46, 8, "Tribute-- Text: Sasha gratuated-- Magna-- Cum- Laude-- from MIT--- with-- a- PHD---- in Computer---- Science----. She-- was-- brilliant--, strong- willed--, and-- a-- stunningly--- beautiful--- woman---. Sasha---- is- the- creator--- of the world's--- first- Ruby--- Quantum-- Machine---. After-- much- critical--- acclaim--, the Quantum-- Computer-- was placed in MIT's---- Museam-- next- to- Richard--- G. and Thomas--- K.'s---- Lisp-- Machine---. Her- engineering--- skills-- were-- paramount--- for Mission--- Serenity's--- success. Humanity-- misses-- you-- dearly,-- Sasha--. Life-- shines-- a dimmer-- light-- now- that- your- angelic- voice-- can never- be heard- again."],
    ],
    scenes: [
      [*hotspot_bottom, :serenity_bio_finally_to_bed]
    ]
  }
end

def serenity_bio_finally_to_bed args
  {
    fade: 60,
    background: 'sprites/inside-home.png',
    player: [35, 3],
    storylines: [
      [34, 4, 4, 4, "Maybe-- I'll-- be able-- to sleep- now..."],
    ],
    scenes: [
      [32, 38, 10, 13, :bad_dream],
    ]
  }
end

def bad_dream args
  {
    fade: 120,
    background: 'sprites/inside-home.png',
    player: [34, 35],
    storylines: [
      [34, 34, 4, 4, "Man. I did not- sleep- well- at all..."],
    ],
    scenes: [
      [32, -1, 8, 3, :bad_dream_observatory]
    ]
  }
end

def bad_dream_observatory args
  {
    background: 'sprites/inside-observatory.png',
    fade: 120,
    player: [51, 12],
    storylines: [
      [50, 10, 4, 4,   "Breathe, Hiro. Just see what's there... everything--- will- be okay."]
    ],
    scenes: [
      [30, 18, 5, 12, :bad_dream_inside_mainframe]
    ],
    render_override: :blinking_light_inside_observatory_render
  }
end

def bad_dream_inside_mainframe args
  {
    player: [32, 4],
    background: 'sprites/mainframe.png',
    fade: 120,
    storylines: [
      [22, 45, 17, 4, (bad_dream_last_reply args)],
    ],
    scenes: [
      [45, 45,  4, 4, :bad_dream_everyone_dead],
    ]
  }
end

def bad_dream_everyone_dead args
  {
    background: 'sprites/mainframe.png',
    storylines: [
      [22, 45, 17, 4, (bad_dream_last_reply args)],
      [45, 45,  4, 4, "Hi-- Hiro. This is Sasha. By the time- you get this- message, chances-- are we will- already-- be- dead. The batteries--- got- damaged-- during-- removal. And- we don't-- have enough-- power-- for Life-- Support. The air-- is- already--- starting-- to taste- bad. It... would- have been- nice... to go- on a date--- with- you-- when-- I- got- back- to Earth. Anyways, good-- bye-- Hiro-- XOXOXO----"],
      [22,  5, 17, 4, "Meh. Whatever, I didn't-- want to save them anyways. What- a pain- in my ass."],
    ],
    scenes: [
      [*hotspot_bottom, :anka_inside_room]
    ]
  }
end

def bad_dream_last_reply args
  if args.state.scene_history.include? :replied_to_serenity_alive_firmly
    return "Buffer--: #{serenity_alive_firm_reply.quote}"
  else
    return "Buffer--: #{serenity_alive_sugarcoated_reply.quote}"
  end
end

    Return Of Serenity - storyline_serenity_introduction.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_serenity_introduction.rb
# decision_graph "Message from Sasha",
#                "I should reply.",
#                [:replied_to_introduction_seriously,  "Reply Seriously", "Who is this?"],
# [:replied_to_introduction_humorously, "Reply Humorously", "New phone who dis?"]
def reply_to_introduction args
  decision_graph  "\"Mission-- control--, your- main- comm-- channels-- seem-- to be down. My apologies-- for- using-- this low- level-- exploit--. What's-- going-- on down there? We are ready-- for reentry--.\" Message--- Timestamp---: 4- hours-- 23--- minutes-- ago--.",
                  "Whoever-- pulled- off this exploit-- knows their stuff. I should reply--.",
                  [:replied_to_introduction_seriously,  "Serious Reply",  "Hello, Who- is sending-- this message--?"],
                  [:replied_to_introduction_humorously, "Humorous Reply", "New phone, who dis?"]
end

def replied_to_introduction_seriously args
  {
    background: 'sprites/inside-observatory.png',
    fade: 60,
    player: [32, 21],
    scenes: [
      *replied_to_introduction_shared_scenes(args)
    ],
    storylines: [
      [30, 18, 5, 12, "Buffer-- has been set to: \"Hello, Who- is sending-- this message--?\""],
      *replied_to_introduction_shared_storylines(args)
    ]
  }
end

def replied_to_introduction_humorously args
  {
    background: 'sprites/inside-observatory.png',
    fade: 60,
    player: [32, 21],
    scenes: [
      *replied_to_introduction_shared_scenes(args)
    ],
    storylines: [
      [30, 18, 5, 12, "Buffer-- has been set to: \"New- phone. Who dis?\""],
      *replied_to_introduction_shared_storylines(args)
    ]
  }
end

def replied_to_introduction_shared_storylines args
  [
    [30, 10, 5, 4, "It's-- going-- to take a while-- for this reply-- to make it's-- way back."],
    [40, 10, 5, 4, "4- hours-- to send a message-- at light speed?! How far away-- is the sender--?"],
    [50, 10, 5, 4, "I know- I've-- read about-- light- speed- travel-- before--. Maybe-- the library--- still has that- poster."]
  ]
end

def replied_to_introduction_shared_scenes args
  [[60, 0, 4, 32, :replied_to_introduction_observatory]]
end

def replied_to_introduction_observatory args
  {
    background: 'sprites/observatory.png',
    player: [28, 39],
    scenes: [
      [60, 0, 4, 32, :replied_to_introduction_path_to_observatory]
    ]
  }
end

def replied_to_introduction_path_to_observatory args
  {
    background: 'sprites/path-to-observatory.png',
    player: [0, 26],
    scenes: [
      [60, 0, 4, 20, :replied_to_introduction_mountain_pass]
    ],
  }
end

def replied_to_introduction_mountain_pass args
  {
    background: 'sprites/mountain-pass-zoomed-out.png',
    player: [21, 48],
    scenes: [
      [0, 0, 15, 4, :replied_to_introduction_side_of_home]
    ],
    storylines: [
      [15, 28, 5, 3, "At least I'm-- getting-- my- exercise-- in- for- today--."]
    ]
  }
end

def replied_to_introduction_side_of_home args
  {
    background: 'sprites/side-of-home.png',
    player: [58, 29],
    scenes: [
      [2, 0, 61, 2, :speed_of_light_front_of_home]
    ],
  }
end

    Return Of Serenity - storyline_speed_of_light.rb link

    # ./samples/99_genre_rpg_narrative/return_of_serenity/app/storyline_speed_of_light.rb
def speed_of_light_front_of_home args
  {
    background: 'sprites/front-of-home.png',
    player: [54, 23],
    scenes: [
      [44, 34, 8, 14, :speed_of_light_inside_home],
      [0, 3, 3, 22, :speed_of_light_outside_library]
    ]
  }
end

def speed_of_light_inside_home args
  {
    background: 'sprites/inside-home.png',
    player: [35, 4],
    storylines: [
      [30, 38, 12, 13, "Can't- sleep right now. I have to- find- out- why- it took- over-- 4- hours-- to receive-- that message."]
    ],
    scenes: [
      [32, 0, 8, 3, :speed_of_light_front_of_home],
    ]
  }
end

def speed_of_light_outside_library args
  {
    background: 'sprites/outside-library.png',
    player: [55, 19],
    scenes: [
      [49, 39, 6, 10, :speed_of_light_library],
      [61, 11, 3, 20, :speed_of_light_front_of_home]
    ]
  }
end

def speed_of_light_library args
  {
    background: 'sprites/library.png',
    player: [30, 7],
    scenes: [
      [3, 50, 10, 3, :speed_of_light_celestial_bodies_diagram]
    ]
  }
end

def speed_of_light_celestial_bodies_diagram args
  {
    background: 'sprites/planets.png',
    fade: 60,
    player: [30, 3],
    scenes: [
      [56 - 2, 10, 5, 5, :speed_of_light_distance_discovered]
    ],
    storylines: [
      [30, 2, 4, 4, "Here- it is! This is a diagram--- of the solar-- system--. It was printed-- over-- fifty-- years- ago. Geez-- that's-- old."],

      [ 0 - 2, 10, 5, 5, "The label- reads: Sun. The length- of the Astronomical-------- Unit-- (AU), is the distance-- from the Sun- to the Earth. Which is about 150--- million--- kilometers----."],
      [ 7 - 2, 10, 5, 5, "The label- reads: Mercury. Distance from Sun: 0.39AU------------ or- 3----- light-- minutes--."],
      [14 - 2, 10, 5, 5, "The label- reads: Venus. Distance from Sun: 0.72AU------------ or- 6----- light-- minutes--."],
      [21 - 2, 10, 5, 5, "The label- reads: Earth. Distance from Sun: 1.00AU------------ or- 8----- light-- minutes--."],
      [28 - 2, 10, 5, 5, "The label- reads: Mars. Distance from Sun: 1.52AU------------ or- 12----- light-- minutes--."],
      [35 - 2, 10, 5, 5, "The label- reads: Jupiter. Distance from Sun: 5.20AU------------ or- 45----- light-- minutes--."],
      [42 - 2, 10, 5, 5, "The label- reads: Saturn. Distance from Sun: 9.53AU------------ or- 79----- light-- minutes--."],
      [49 - 2, 10, 5, 5, "The label- reads: Uranus. Distance from Sun: 19.81AU------------ or- 159----- light-- minutes--."],
      # [56 - 2, 15, 4, 4, "The label- reads: Neptune. Distance from Sun: 30.05AU------------ or- 4.1----- light-- hours--."],
      [63 - 2, 10, 5, 5, "The label- reads: Pluto. Wait. WTF? Pluto-- isn't-- a planet."],
    ]
  }
end

def speed_of_light_distance_discovered args
  {
    background: 'sprites/planets.png',
    scenes: [
      [13, 0, 44, 3, :speed_of_light_end_of_day]
    ],
    storylines: [
      [ 0 - 2, 10, 5, 5, "The label- reads: Sun. The length- of the Astronomical-------- Unit-- (AU), is the distance-- from the Sun- to the Earth. Which is about 150--- million--- kilometers----."],
      [ 7 - 2, 10, 5, 5, "The label- reads: Mercury. Distance from Sun: 0.39AU------------ or- 3----- light-- minutes--."],
      [14 - 2, 10, 5, 5, "The label- reads: Venus. Distance from Sun: 0.72AU------------ or- 6----- light-- minutes--."],
      [21 - 2, 10, 5, 5, "The label- reads: Earth. Distance from Sun: 1.00AU------------ or- 8----- light-- minutes--."],
      [28 - 2, 10, 5, 5, "The label- reads: Mars. Distance from Sun: 1.52AU------------ or- 12----- light-- minutes--."],
      [35 - 2, 10, 5, 5, "The label- reads: Jupiter. Distance from Sun: 5.20AU------------ or- 45----- light-- minutes--."],
      [42 - 2, 10, 5, 5, "The label- reads: Saturn. Distance from Sun: 9.53AU------------ or- 79----- light-- minutes--."],
      [49 - 2, 10, 5, 5, "The label- reads: Uranus. Distance from Sun: 19.81AU------------ or- 159----- light-- minutes--."],
      [56 - 2, 10, 5, 5, "The label- reads: Neptune. Distance from Sun: 30.05AU------------ or- 4.1----- light-- hours--. What?! The message--- I received-- was from a source-- farther-- than-- Neptune?!"],
      [63 - 2, 10, 5, 5, "The label- reads: Pluto. Dista- Wait... Pluto-- isn't-- a planet. People-- thought- Pluto-- was a planet-- back- then?--"],
    ]
  }
end

def speed_of_light_end_of_day args
  {
    fade: 60,
    background: 'sprites/inside-home.png',
    player: [35, 0],
    storylines: [
      [35, 10, 4, 4, "Wonder-- what the reply-- will be. Who- the hell is contacting--- me from beyond-- Neptune? This- has to be some- kind- of- joke."]
    ],
    scenes: [
      [31, 38, 10, 12, :serenity_alive_side_of_home]
    ]
  }
end

    Genre Rpg Roguelike link

    Roguelike Starting Point - constants.rb link

    # ./samples/99_genre_rpg_roguelike/01_roguelike_starting_point/app/constants.rb
SHOW_LEGEND = true
SOURCE_TILE_SIZE = 16
DESTINATION_TILE_SIZE = 16
TILE_SHEET_SIZE = 256
TILE_R = 0
TILE_G = 0
TILE_B = 0
TILE_A = 255

    Roguelike Starting Point - legend.rb link

    # ./samples/99_genre_rpg_roguelike/01_roguelike_starting_point/app/legend.rb
def tick_legend args
  return unless SHOW_LEGEND

  legend_padding = 16
  legend_x = 1280 - TILE_SHEET_SIZE - legend_padding
  legend_y =  720 - TILE_SHEET_SIZE - legend_padding
  tile_sheet_sprite = [legend_x,
                       legend_y,
                       TILE_SHEET_SIZE,
                       TILE_SHEET_SIZE,
                       'sprites/simple-mood-16x16.png', 0,
                       TILE_A,
                       TILE_R,
                       TILE_G,
                       TILE_B]

  if args.inputs.mouse.point.inside_rect? tile_sheet_sprite
    mouse_row = args.inputs.mouse.point.y.idiv(SOURCE_TILE_SIZE)
    tile_row = 15 - (mouse_row - legend_y.idiv(SOURCE_TILE_SIZE))

    mouse_col = args.inputs.mouse.point.x.idiv(SOURCE_TILE_SIZE)
    tile_col = (mouse_col - legend_x.idiv(SOURCE_TILE_SIZE))

    args.outputs.primitives << [legend_x - legend_padding * 2,
                                mouse_row * SOURCE_TILE_SIZE, 256 + legend_padding * 2, 16, 128, 128, 128, 64].solid

    args.outputs.primitives << [mouse_col * SOURCE_TILE_SIZE,
                                legend_y - legend_padding * 2, 16, 256 + legend_padding * 2, 128, 128, 128, 64].solid

    sprite_key = sprite_lookup.find { |k, v| v == [tile_row, tile_col] }
    if sprite_key
      member_name, _ = sprite_key
      member_name = member_name_as_code member_name
      args.outputs.labels << [660, 70, "# CODE SAMPLE (place in the tick_game method located in main.rb)", -1, 0]
      args.outputs.labels << [660, 50, "#                                    GRID_X, GRID_Y, TILE_KEY", -1, 0]
      args.outputs.labels << [660, 30, "args.outputs.sprites << tile_in_game(     5,      6, #{member_name}    )", -1, 0]
    else
      args.outputs.labels << [660, 50, "Tile [#{tile_row}, #{tile_col}] not found. Add a key and value to app/sprite_lookup.rb:", -1, 0]
      args.outputs.labels << [660, 30, "{ \"some_string\" => [#{tile_row}, #{tile_col}] } OR { some_symbol: [#{tile_row}, #{tile_col}] }.", -1, 0]
    end

  end

  # render the sprite in the top right with a padding to the top and right so it's
  # not flush against the edge
  args.outputs.sprites << tile_sheet_sprite

  # carefully place some ascii arrows to show the legend labels
  args.outputs.labels  <<  [895, 707, "ROW --->"]
  args.outputs.labels  <<  [943, 412, "       ^"]
  args.outputs.labels  <<  [943, 412, "       |"]
  args.outputs.labels  <<  [943, 394, "COL ---+"]

  # use the tile sheet to print out row and column numbers
  args.outputs.sprites << 16.map_with_index do |i|
    sprite_key = i % 10
    [
      tile(1280 - TILE_SHEET_SIZE - legend_padding * 2 - SOURCE_TILE_SIZE,
            720 - legend_padding * 2 - (SOURCE_TILE_SIZE * i),
            sprite(sprite_key)),
      tile(1280 - TILE_SHEET_SIZE - SOURCE_TILE_SIZE + (SOURCE_TILE_SIZE * i),
            720 - TILE_SHEET_SIZE - legend_padding * 3, sprite(sprite_key))
    ]
  end
end

    Roguelike Starting Point - main.rb link

    # ./samples/99_genre_rpg_roguelike/01_roguelike_starting_point/app/main.rb
require 'app/constants.rb'
require 'app/sprite_lookup.rb'
require 'app/legend.rb'

def tick args
  tick_game args
  tick_legend args
end

def tick_game args
  # setup the grid
  args.state.grid.padding = 104
  args.state.grid.size = 512

  # set up your game
  # initialize the game/game defaults. ||= means that you only initialize it if
  # the value isn't alread initialized
  args.state.player.x ||= 0
  args.state.player.y ||= 0

  args.state.enemies ||= [
    { x: 10, y: 10, type: :goblin, tile_key: :G },
    { x: 15, y: 30, type: :rat,    tile_key: :R }
  ]

  args.state.info_message ||= "Use arrow keys to move around."

  # handle keyboard input
  # keyboard input (arrow keys to move player)
  new_player_x = args.state.player.x
  new_player_y = args.state.player.y
  player_direction = ""
  player_moved = false
  if args.inputs.keyboard.key_down.up
    new_player_y += 1
    player_direction = "north"
    player_moved = true
  elsif args.inputs.keyboard.key_down.down
    new_player_y -= 1
    player_direction = "south"
    player_moved = true
  elsif args.inputs.keyboard.key_down.right
    new_player_x += 1
    player_direction = "east"
    player_moved = true
  elsif args.inputs.keyboard.key_down.left
    new_player_x -= 1
    player_direction = "west"
    player_moved = true
  end

  #handle game logic
  # determine if there is an enemy on that square,
  # if so, don't let the player move there
  if player_moved
    found_enemy = args.state.enemies.find do |e|
      e[:x] == new_player_x && e[:y] == new_player_y
    end

    if !found_enemy
      args.state.player.x = new_player_x
      args.state.player.y = new_player_y
      args.state.info_message = "You moved #{player_direction}."
    else
      args.state.info_message = "You cannot move into a square an enemy occupies."
    end
  end

  args.outputs.sprites << tile_in_game(args.state.player.x,
                                       args.state.player.y, '@')

  # render game
  # render enemies at locations
  args.outputs.sprites << args.state.enemies.map do |e|
    tile_in_game(e[:x], e[:y], e[:tile_key])
  end

  # render the border
  border_x = args.state.grid.padding - DESTINATION_TILE_SIZE
  border_y = args.state.grid.padding - DESTINATION_TILE_SIZE
  border_size = args.state.grid.size + DESTINATION_TILE_SIZE * 2

  args.outputs.borders << [border_x,
                           border_y,
                           border_size,
                           border_size]

  # render label stuff
  args.outputs.labels << [border_x, border_y - 10, "Current player location is: #{args.state.player.x}, #{args.state.player.y}"]
  args.outputs.labels << [border_x, border_y + 25 + border_size, args.state.info_message]
end

def tile_in_game x, y, tile_key
  tile($gtk.args.state.grid.padding + x * DESTINATION_TILE_SIZE,
       $gtk.args.state.grid.padding + y * DESTINATION_TILE_SIZE,
       tile_key)
end

    Roguelike Starting Point - sprite_lookup.rb link

    # ./samples/99_genre_rpg_roguelike/01_roguelike_starting_point/app/sprite_lookup.rb
def sprite_lookup
  {
    0 => [3, 0],
    1 => [3, 1],
    2 => [3, 2],
    3 => [3, 3],
    4 => [3, 4],
    5 => [3, 5],
    6 => [3, 6],
    7 => [3, 7],
    8 => [3, 8],
    9 => [3, 9],
    '@' => [4, 0],
    A: [ 4,  1],
    B: [ 4,  2],
    C: [ 4,  3],
    D: [ 4,  4],
    E: [ 4,  5],
    F: [ 4,  6],
    G: [ 4,  7],
    H: [ 4,  8],
    I: [ 4,  9],
    J: [ 4, 10],
    K: [ 4, 11],
    L: [ 4, 12],
    M: [ 4, 13],
    N: [ 4, 14],
    O: [ 4, 15],
    P: [ 5,  0],
    Q: [ 5,  1],
    R: [ 5,  2],
    S: [ 5,  3],
    T: [ 5,  4],
    U: [ 5,  5],
    V: [ 5,  6],
    W: [ 5,  7],
    X: [ 5,  8],
    Y: [ 5,  9],
    Z: [ 5, 10],
    a: [ 6,  1],
    b: [ 6,  2],
    c: [ 6,  3],
    d: [ 6,  4],
    e: [ 6,  5],
    f: [ 6,  6],
    g: [ 6,  7],
    h: [ 6,  8],
    i: [ 6,  9],
    j: [ 6, 10],
    k: [ 6, 11],
    l: [ 6, 12],
    m: [ 6, 13],
    n: [ 6, 14],
    o: [ 6, 15],
    p: [ 7,  0],
    q: [ 7,  1],
    r: [ 7,  2],
    s: [ 7,  3],
    t: [ 7,  4],
    u: [ 7,  5],
    v: [ 7,  6],
    w: [ 7,  7],
    x: [ 7,  8],
    y: [ 7,  9],
    z: [ 7, 10],
    '|' => [ 7, 12]
  }
end

def sprite key
  $gtk.args.state.reserved.sprite_lookup[key]
end

def member_name_as_code raw_member_name
  if raw_member_name.is_a? Symbol
    ":#{raw_member_name}"
  elsif raw_member_name.is_a? String
    "'#{raw_member_name}'"
  elsif raw_member_name.is_a? Fixnum
    "#{raw_member_name}"
  else
    "UNKNOWN: #{raw_member_name}"
  end
end

def tile x, y, tile_row_column_or_key
  tile_extended x, y, DESTINATION_TILE_SIZE, DESTINATION_TILE_SIZE, TILE_R, TILE_G, TILE_B, TILE_A, tile_row_column_or_key
end

def tile_extended x, y, w, h, r, g, b, a, tile_row_column_or_key
  row_or_key, column = tile_row_column_or_key
  if !column
    row, column = sprite row_or_key
  else
    row, column = row_or_key, column
  end

  if !row
    member_name = member_name_as_code tile_row_column_or_key
    raise "Unabled to find a sprite for #{member_name}. Make sure the value exists in app/sprite_lookup.rb."
  end

  # Sprite provided by Rogue Yun
  # http://www.bay12forums.com/smf/index.php?topic=144897.0
  # License: Public Domain

  {
    x: x,
    y: y,
    w: w,
    h: h,
    tile_x: column * 16,
    tile_y: (row * 16),
    tile_w: 16,
    tile_h: 16,
    r: r,
    g: g,
    b: b,
    a: a,
    path: 'sprites/simple-mood-16x16.png'
  }
end

$gtk.args.state.reserved.sprite_lookup = sprite_lookup

    Roguelike Line Of Sight - main.rb link

    # ./samples/99_genre_rpg_roguelike/02_roguelike_line_of_sight/app/main.rb
=begin

 APIs listing that haven't been encountered in previous sample apps:

 - lambda: A way to define a block and its parameters with special syntax.
   For example, the syntax of lambda looks like this:
   my_lambda = -> { puts "This is my lambda" }

 Reminders:
 - args.outputs.labels: An array. The values generate a label.
   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
   For more information about labels, go to mygame/documentation/02-labels.

 - ARRAY#inside_rect?: Returns whether or not the point is inside a rect.

 - product: Returns an array of all combinations of elements from all arrays.

 - find: Finds all elements of a collection that meet requirements.

 - abs: Returns the absolute value.

=end

# This sample app allows the player to move around in the dungeon, which becomes more or less visible
# depending on the player's location, and also has enemies.

class Game
  attr_accessor :args, :state, :inputs, :outputs, :grid

  # Calls all the methods needed for the game to run properly.
  def tick
    defaults
    render_canvas
    render_dungeon
    render_player
    render_enemies
    print_cell_coordinates
    calc_canvas
    input_move
    input_click_map
  end

  # Sets default values and initializes variables
  def defaults
    outputs.background_color = [0, 0, 0] # black background

    # Initializes empty canvas, dungeon, and enemies collections.
    state.canvas   ||= []
    state.dungeon  ||= []
    state.enemies  ||= []

    # If state.area doesn't have value, load_area_one and derive_dungeon_from_area methods are called
    if !state.area
      load_area_one
      derive_dungeon_from_area

      # Changing these values will change the position of player
      state.x = 7
      state.y = 5

      # Creates new enemies, sets their values, and adds them to the enemies collection.
      state.enemies << state.new_entity(:enemy) do |e| # declares each enemy as new entity
        e.x           = 13 # position
        e.y           = 5
        e.previous_hp = 3
        e.hp          = 3
        e.max_hp      = 3
        e.is_dead     = false # the enemy is alive
      end

      update_line_of_sight # updates line of sight by adding newly visible cells
    end
  end

  # Adds elements into the state.area collection
  # The dungeon is derived using the coordinates of this collection
  def load_area_one
    state.area ||= []
    state.area << [8, 6]
    state.area << [7, 6]
    state.area << [7, 7]
    state.area << [8, 9]
    state.area << [7, 8]
    state.area << [7, 9]
    state.area << [6, 4]
    state.area << [7, 3]
    state.area << [7, 4]
    state.area << [6, 5]
    state.area << [7, 5]
    state.area << [8, 5]
    state.area << [8, 4]
    state.area << [1, 1]
    state.area << [0, 1]
    state.area << [0, 2]
    state.area << [1, 2]
    state.area << [2, 2]
    state.area << [2, 1]
    state.area << [2, 3]
    state.area << [1, 3]
    state.area << [1, 4]
    state.area << [2, 4]
    state.area << [2, 5]
    state.area << [1, 5]
    state.area << [2, 6]
    state.area << [3, 6]
    state.area << [4, 6]
    state.area << [4, 7]
    state.area << [4, 8]
    state.area << [5, 8]
    state.area << [5, 9]
    state.area << [6, 9]
    state.area << [7, 10]
    state.area << [7, 11]
    state.area << [7, 12]
    state.area << [7, 12]
    state.area << [7, 13]
    state.area << [8, 13]
    state.area << [9, 13]
    state.area << [10, 13]
    state.area << [11, 13]
    state.area << [12, 13]
    state.area << [12, 12]
    state.area << [8, 12]
    state.area << [9, 12]
    state.area << [10, 12]
    state.area << [11, 12]
    state.area << [12, 11]
    state.area << [13, 11]
    state.area << [13, 10]
    state.area << [13, 9]
    state.area << [13, 8]
    state.area << [13, 7]
    state.area << [13, 6]
    state.area << [12, 6]
    state.area << [14, 6]
    state.area << [14, 5]
    state.area << [13, 5]
    state.area << [12, 5]
    state.area << [12, 4]
    state.area << [13, 4]
    state.area << [14, 4]
    state.area << [1, 6]
    state.area << [6, 6]
  end

  # Starts with an empty dungeon collection, and adds dungeon cells into it.
  def derive_dungeon_from_area
    state.dungeon = [] # starts as empty collection

    state.area.each do |a| # for each element of the area collection
      state.dungeon << state.new_entity(:dungeon_cell) do |d| # declares each dungeon cell as new entity
        d.x = a.x # dungeon cell position using coordinates from area
        d.y = a.y
        d.is_visible = false # cell is not visible
        d.alpha = 0 # not transparent at all
        d.border = [left_margin   + a.x * grid_size,
                    bottom_margin + a.y * grid_size,
                    grid_size,
                    grid_size,
                    *blue,
                    255] # sets border definition for dungeon cell
        d # returns dungeon cell
      end
    end
  end

  def left_margin
    40  # sets left margin
  end

  def bottom_margin
    60 # sets bottom margin
  end

  def grid_size
    40 # sets size of grid square
  end

  # Updates the line of sight by calling the thick_line_of_sight method and
  # adding dungeon cells to the newly_visible collection
  def update_line_of_sight
    variations = [-1, 0, 1]
    # creates collection of newly visible dungeon cells
    newly_visible = variations.product(variations).flat_map do |rise, run| # combo of all elements
      thick_line_of_sight state.x, state.y, rise, run, 15, # calls thick_line_of_sight method
                          lambda { |x, y| dungeon_cell_exists? x, y } # checks whether or not cell exists
    end.uniq# removes duplicates

    state.dungeon.each do |d| # perform action on each element of dungeons collection
      d.is_visible = newly_visible.find { |v| v.x == d.x && v.y == d.y } # finds match inside newly_visible collection
    end
  end

  #Returns a boolean value
  def dungeon_cell_exists? x, y
    # Finds cell coordinates inside dungeon collection to determine if dungeon cell exists
    state.dungeon.find { |d| d.x == x && d.y == y }
  end

  # Calls line_of_sight method to add elements to result collection
  def thick_line_of_sight start_x, start_y, rise, run, distance, cell_exists_lambda
    result = []
    result += line_of_sight start_x, start_y, rise, run, distance, cell_exists_lambda
    result += line_of_sight start_x - 1, start_y, rise, run, distance, cell_exists_lambda # one left
    result += line_of_sight start_x + 1, start_y, rise, run, distance, cell_exists_lambda # one right
    result
  end

  # Adds points to the result collection to create the player's line of sight
  def line_of_sight start_x, start_y, rise, run, distance, cell_exists_lambda
    result = [] # starts as empty collection
    points = points_on_line start_x, start_y, rise, run, distance # calls points_on_line method
    points.each do |p| # for each point in collection
      if cell_exists_lambda.call(p.x, p.y) # if the cell exists
        result << p # add it to result collection
      else # if cell does not exist
        return result # return result collection as it is
      end
    end

    result # return result collection
  end

  # Finds the coordinates of the points on the line by performing calculations
  def points_on_line start_x, start_y, rise, run, distance
    distance.times.map do |i| # perform an action
      [start_x + run * i, start_y + rise * i] # definition of point
    end
  end

  def render_canvas
    return
    outputs.borders << state.canvas.map do |c| # on each element of canvas collection
      c.border # outputs border
    end
  end

  # Outputs the dungeon cells.
  def render_dungeon
    outputs.solids << [0, 0, grid.w, grid.h] # outputs black background for grid

    # Sets the alpha value (opacity) for each dungeon cell and calls the cell_border method.
    outputs.borders << state.dungeon.map do |d| # for each element in dungeon collection
      d.alpha += if d.is_visible # if cell is visible
                 255.fdiv(30) # increment opacity (transparency)
               else # if cell is not visible
                 255.fdiv(600) * -1 # decrease opacity
               end
      d.alpha = d.alpha.cap_min_max(0, 255)
      cell_border d.x, d.y, [*blue, d.alpha] # sets blue border using alpha value
    end.reject_nil
  end

  # Sets definition of a cell border using the parameters
  def cell_border x, y, color = nil
    [left_margin   + x * grid_size,
    bottom_margin + y * grid_size,
    grid_size,
    grid_size,
    *color]
  end

  # Sets the values for the player and outputs it as a label
  def render_player
    outputs.labels << [grid_x(state.x) + 20, # positions "@" text in center of grid square
                     grid_y(state.y) + 35,
                     "@", # player is represented by a white "@" character
                     1, 1, *white]
  end

  def grid_x x
    left_margin + x * grid_size # positions horizontally on grid
  end

  def grid_y y
    bottom_margin + y * grid_size # positions vertically on grid
  end

  # Outputs enemies onto the screen.
  def render_enemies
    state.enemies.map do |e| # for each enemy in the collection
      alpha = 255 # set opacity (full transparency)

      # Outputs an enemy using a label.
      outputs.labels << [
                   left_margin + 20 +  e.x * grid_size, # positions enemy's "r" text in center of grid square
                   bottom_margin + 35 + e.y * grid_size,
                   "r", # enemy's text
                   1, 1, *white, alpha]

      # Creates a red border around an enemy.
      outputs.borders << [grid_x(e.x), grid_y(e.y), grid_size, grid_size, *red]
    end
  end

  #White labels are output for the cell coordinates of each element in the dungeon collection.
  def print_cell_coordinates
    return unless state.debug
    state.dungeon.each do |d|
      outputs.labels << [grid_x(d.x) + 2,
                         grid_y(d.y) - 2,
                         "#{d.x},#{d.y}",
                         -2, 0, *white]
    end
  end

  # Adds new elements into the canvas collection and sets their values.
  def calc_canvas
    return if state.canvas.length > 0 # return if canvas collection has at least one element
    15.times do |x| # 15 times perform an action
      15.times do |y|
        state.canvas << state.new_entity(:canvas) do |c| # declare canvas element as new entity
          c.x = x # set position
          c.y = y
          c.border = [left_margin   + x * grid_size,
                      bottom_margin + y * grid_size,
                      grid_size,
                      grid_size,
                      *white, 30] # sets border definition
        end
      end
    end
  end

  # Updates x and y values of the player, and updates player's line of sight
  def input_move
    x, y, x_diff, y_diff = input_target_cell

    return unless dungeon_cell_exists? x, y # player can't move there if a dungeon cell doesn't exist in that location
    return if enemy_at x, y # player can't move there if there is an enemy in that location

    state.x += x_diff # increments x by x_diff (so player moves left or right)
    state.y += y_diff # same with y and y_diff ( so player moves up or down)
    update_line_of_sight # updates visible cells
  end

  def enemy_at x, y
    # Finds if coordinates exist in enemies collection and enemy is not dead
    state.enemies.find { |e| e.x == x && e.y == y && !e.is_dead }
  end

  #M oves the user based on their keyboard input and sets values for target cell
  def input_target_cell
    if inputs.keyboard.key_down.up # if "up" key is in "down" state
      [state.x, state.y + 1,  0,  1] # user moves up
    elsif inputs.keyboard.key_down.down # if "down" key is pressed
      [state.x, state.y - 1,  0, -1] # user moves down
    elsif inputs.keyboard.key_down.left # if "left" key is pressed
      [state.x - 1, state.y, -1,  0] # user moves left
    elsif inputs.keyboard.key_down.right # if "right" key is pressed
      [state.x + 1, state.y,  1,  0] # user moves right
    else
      nil  # otherwise, empty
    end
  end

  # Goes through the canvas collection to find if the mouse was clicked inside of the borders of an element.
  def input_click_map
    return unless inputs.mouse.click # return unless the mouse is clicked
    canvas_entry = state.canvas.find do |c| # find element from canvas collection that meets requirements
      inputs.mouse.click.inside_rect? c.border # find border that mouse was clicked inside of
    end
    puts canvas_entry # prints canvas_entry value
  end

  # Sets the definition of a label using the parameters.
  def label text, x, y, color = nil
    color ||= white # color is initialized to white
    [x, y, text, 1, 1, *color] # sets label definition
  end

  def green
    [60, 200, 100] # sets color saturation to shade of green
  end

  def blue
    [50, 50, 210] # sets color saturation to shade of blue
  end

  def white
    [255, 255, 255] # sets color saturation to white
  end

  def red
    [230, 80, 80] # sets color saturation to shade of red
  end

  def orange
    [255, 80, 60] # sets color saturation to shade of orange
  end

  def pink
    [255, 0, 200] # sets color saturation to shade of pink
  end

  def gray
    [75, 75, 75] # sets color saturation to shade of gray
  end

  # Recolors the border using the parameters.
  def recolor_border border, r, g, b
    border[4] = r
    border[5] = g
    border[6] = b
    border
  end

  # Returns a boolean value.
  def visible? cell
    # finds cell's coordinates inside visible_cells collections to determine if cell is visible
    state.visible_cells.find { |c| c.x == cell.x && c.y == cell.y}
  end

  # Exports dungeon by printing dungeon cell coordinates
  def export_dungeon
    state.dungeon.each do |d| # on each element of dungeon collection
      puts "state.dungeon << [#{d.x}, #{d.y}]" # prints cell coordinates
    end
  end

  def distance_to_cell cell
    distance_to state.x, cell.x, state.y, cell.y # calls distance_to method
  end

  def distance_to from_x, x, from_y, y
    (from_x - x).abs + (from_y - y).abs # finds distance between two cells using coordinates
  end
end

$game = Game.new

def tick args
  $game.args    = args
  $game.state   = args.state
  $game.inputs  = args.inputs
  $game.outputs = args.outputs
  $game.grid    = args.grid
  $game.tick
end

    Genre Rpg Tactical link

    Hexagonal Grid - main.rb link

    # ./samples/99_genre_rpg_tactical/hexagonal_grid/app/main.rb
class HexagonTileGame
  attr_gtk

  def defaults
    state.tile_scale      = 1.3
    state.tile_size       = 80
    state.tile_w          = Math.sqrt(3) * state.tile_size.half
    state.tile_h          = state.tile_size * 3/4
    state.tiles_x_count   = 1280.idiv(state.tile_w) - 1
    state.tiles_y_count   = 720.idiv(state.tile_h) - 1
    state.world_width_px  = state.tiles_x_count * state.tile_w
    state.world_height_px = state.tiles_y_count * state.tile_h
    state.world_x_offset  = (1280 - state.world_width_px).half
    state.world_y_offset  = (720 - state.world_height_px).half
    state.tiles         ||= state.tiles_x_count.map_with_ys(state.tiles_y_count) do |ordinal_x, ordinal_y|
      {
        ordinal_x: ordinal_x,
        ordinal_y: ordinal_y,
        offset_x: (ordinal_y.even?) ?
                  (state.world_x_offset + state.tile_w.half.half) :
                  (state.world_x_offset - state.tile_w.half.half),
        offset_y: state.world_y_offset,
        w: state.tile_w,
        h: state.tile_h,
        type: :blank,
        path: "sprites/hexagon-gray.png",
        a: 20
      }.associate do |h|
        h.merge(x: h[:offset_x] + h[:ordinal_x] * h[:w],
                y: h[:offset_y] + h[:ordinal_y] * h[:h]).scale_rect(state.tile_scale)
      end.associate do |h|
        h.merge(center: {
                  x: h[:x] + h[:w].half,
                  y: h[:y] + h[:h].half
                }, radius: [h[:w].half, h[:h].half].max)
      end
    end
  end

  def input
    if inputs.click
      tile = state.tiles.find { |t| inputs.click.point_inside_circle? t[:center], t[:radius] }
      if tile
        tile[:a] = 255
        tile[:path] = "sprites/hexagon-black.png"
      end
    end
  end

  def tick
    defaults
    input
    render
  end

  def render
    outputs.sprites << state.tiles
  end
end

$game = HexagonTileGame.new

def tick args
  $game.args = args
  $game.tick
end

$gtk.reset

    Isometric Grid - main.rb link

    # ./samples/99_genre_rpg_tactical/isometric_grid/app/main.rb
class Isometric
    attr_accessor :grid, :inputs, :state, :outputs

    def tick
        defaults
        render
        calc
        process_inputs
    end

    def defaults
        state.quantity              ||= 6                                                        #Size of grid
        state.tileSize              ||= [262 / 2, 194 / 2]                                       #width and heigth of orange tiles
        state.tileGrid              ||= []                                                       #Holds ordering of tiles
        state.currentSpriteLocation ||= -1                                                       #Current Sprite hovering location
        state.tileCords             ||= []                                                       #Physical, rendering cordinates
        state.initCords             ||= [640 - (state.quantity / 2 * state.tileSize[0]), 330]    #Location of tile (0, 0)
        state.sideSize              ||= [state.tileSize[0] / 2, 242 / 2]                         #Purple & green cube face size
        state.mode                  ||= :delete                                                  #Switches between :delete and :insert
        state.spriteSelection       ||= [['river',    0, 0, 262 / 2, 194 / 2],
                                         ['mountain', 0, 0, 262 / 2, 245 / 2],
                                         ['ocean',    0, 0, 262 / 2, 194 / 2]]             #Storage for sprite information
                                                                                           #['name', deltaX, deltaY, sizeW, sizeH]
                                                                                           #^delta refers to distance from tile cords

        #Orders tiles based on tile placement and fancy math. Very left: 0,0. Very bottom: quantity-1, 0, etc
        if state.tileGrid == []
            tempX = 0
            tempY = 0
            tempLeft = false
            tempRight = false
            count = 0
            (state.quantity * state.quantity).times do
                if tempY == 0
                    tempLeft = true
                end
                if tempX == (state.quantity - 1)
                    tempRight = true
                end
                state.tileGrid.push([tempX, tempY, true, tempLeft, tempRight, count])
                    #orderX, orderY, exists?, leftSide, rightSide, order
                tempX += 1
                if tempX == state.quantity
                    tempX = 0
                    tempY += 1
                end
                tempLeft = false
                tempRight = false
                count += 1
            end
        end

        #Calculates physical cordinates for tiles
        if state.tileCords == []
            state.tileCords = state.tileGrid.map do
                |val|
                x = (state.initCords[0]) + ((val[0] + val[1]) * state.tileSize[0] / 2)
                y = (state.initCords[1]) + (-1 * val[0] * state.tileSize[1] / 2) + (val[1] * state.tileSize[1] / 2)
                [x, y, val[2], val[3], val[4], val[5], -1] #-1 represents sprite on top of tile. -1 for now
            end
        end

    end

    def render
        renderBackground
        renderLeft
        renderRight
        renderTiles
        renderObjects
        renderLabels
    end

    def renderBackground
        outputs.solids << [0, 0, 1280, 720, 0, 0, 0]   #Background color
    end

    def renderLeft
        #Shows the pink left cube face
        outputs.sprites << state.tileCords.map do
            |val|
            if val[2] == true && val[3] == true       #Checks if the tile exists and right face needs to be rendered
                [val[0], val[1] + (state.tileSize[1] / 2) - state.sideSize[1], state.sideSize[0],
                state.sideSize[1], 'sprites/leftSide.png']
            end
        end
    end

    def renderRight
        #Shows the green right cube face
        outputs.sprites << state.tileCords.map do
            |val|
            if val[2] == true && val[4] == true        #Checks if it exists & checks if right face needs to be rendered
                [val[0] + state.tileSize[0] / 2, val[1] + (state.tileSize[1] / 2) - state.sideSize[1], state.sideSize[0],
                state.sideSize[1], 'sprites/rightSide.png']
            end
        end
    end

    def renderTiles
        #Shows the tile itself. Important that it's rendered after the two above!
        outputs.sprites << state.tileCords.map do
            |val|
            if val[2] == true     #Chcekcs if tile needs to be rendered
              if val[5] == state.currentSpriteLocation
                [val[0], val[1], state.tileSize[0], state.tileSize[1], 'sprites/selectedTile.png']
              else
                [val[0], val[1], state.tileSize[0], state.tileSize[1], 'sprites/tile.png']
              end
            end
        end
    end

    def renderObjects
        #Renders the sprites on top of the tiles. Order of rendering: top corner to right corner and cascade down until left corner
        #to bottom corner.
        a = (state.quantity * state.quantity) - state.quantity
        iter = 0
        loop do
            if state.tileCords[a][2] == true && state.tileCords[a][6] != -1
                outputs.sprites << [state.tileCords[a][0] + state.spriteSelection[state.tileCords[a][6]][1],
                                    state.tileCords[a][1] + state.spriteSelection[state.tileCords[a][6]][2],
                                    state.spriteSelection[state.tileCords[a][6]][3], state.spriteSelection[state.tileCords[a][6]][4],
                                    'sprites/' + state.spriteSelection[state.tileCords[a][6]][0] + '.png']
            end
            iter += 1
            a    += 1
            a -= state.quantity * 2 if iter == state.quantity
            iter = 0                if iter == state.quantity
            break if a < 0
        end
    end

    def renderLabels
        #Labels
        outputs.labels << [50, 680, 'Click to delete!',             5, 0, 255, 255, 255, 255] if state.mode == :delete
        outputs.labels << [50, 640, 'Press \'i\' for insert mode!', 5, 0, 255, 255, 255, 255] if state.mode == :delete
        outputs.labels << [50, 680, 'Click to insert!',             5, 0, 255, 255, 255, 255] if state.mode == :insert
        outputs.labels << [50, 640, 'Press \'d\' for delete mode!', 5, 0, 255, 255, 255, 255] if state.mode == :insert
    end

    def calc
        calcCurrentHover
    end

    def calcCurrentHover
        #This determines what tile the mouse is hovering (or last hovering) over
        x = inputs.mouse.position.x
        y = inputs.mouse.position.y
        m = (state.tileSize[1] / state.tileSize[0])   #slope
        state.tileCords.map do
            |val|
            #Conditions that makes runtime faster. Checks if the mouse click was between tile dimensions (rectangle collision)
            next unless val[0] < x && x < val[0] + state.tileSize[0]
            next unless val[1] < y && y < val[1] + state.tileSize[1]
            next unless val[2] == true
            tempBool = false
            if x == val[0] + (state.tileSize[0] / 2)
                #The height of a diamond is the height of the diamond, so if x equals that exact point, it must be inside the diamond
                tempBool = true
            elsif x < state.tileSize[0] / 2 + val[0]
                #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the left half of diamond
                tempY1 =      (m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
                tempY2 = (-1 * m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
                #Checks to see if the mouse click y value is between those temp y values
                tempBool = true if y < tempY1 && y > tempY2
            elsif x > state.tileSize[0] / 2 + val[0]
                #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the right half of diamond
                tempY1 =      (m * (x - val[0] - (state.tileSize[0] / 2))) + val[1]
                tempY2 = (-1 * m * (x - val[0] - (state.tileSize[0] / 2))) + val[1] + state.tileSize[1]
                #Checks to see if the mouse click y value is between those temp y values
                tempBool = true if y > tempY1 && y < tempY2
            end

            if tempBool == true
                state.currentSpriteLocation = val[5]         #Current sprite location set to the order value
            end
        end
    end

    def process_inputs
        #Makes development much faster and easier
        if inputs.keyboard.key_up.r
            $dragon.reset
        end
        checkTileSelected
        switchModes
    end

    def checkTileSelected
        if inputs.mouse.down
            x = inputs.mouse.down.point.x
            y = inputs.mouse.down.point.y
            m = (state.tileSize[1] / state.tileSize[0])   #slope
            state.tileCords.map do
                |val|
                #Conditions that makes runtime faster. Checks if the mouse click was between tile dimensions (rectangle collision)
                next unless val[0] < x && x < val[0] + state.tileSize[0]
                next unless val[1] < y && y < val[1] + state.tileSize[1]
                next unless val[2] == true
                tempBool = false
                if x == val[0] + (state.tileSize[0] / 2)
                    #The height of a diamond is the height of the diamond, so if x equals that exact point, it must be inside the diamond
                    tempBool = true
                elsif x < state.tileSize[0] / 2 + val[0]
                    #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the left half of diamond
                    tempY1 =      (m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
                    tempY2 = (-1 * m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
                    #Checks to see if the mouse click y value is between those temp y values
                    tempBool = true if y < tempY1 && y > tempY2
                elsif x > state.tileSize[0] / 2 + val[0]
                    #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the right half of diamond
                    tempY1 =      (m * (x - val[0] - (state.tileSize[0] / 2))) + val[1]
                    tempY2 = (-1 * m * (x - val[0] - (state.tileSize[0] / 2))) + val[1] + state.tileSize[1]
                    #Checks to see if the mouse click y value is between those temp y values
                    tempBool = true if y > tempY1 && y < tempY2
                end

                if tempBool == true
                    if state.mode == :delete
                        val[2] = false
                        state.tileGrid[val[5]][2]  = false      #Unnecessary because never used again but eh, I like consistency
                        state.tileCords[val[5]][2] = false      #Ensures that the tile isn't rendered
                        unless state.tileGrid[val[5]][0] == 0   #If tile is the left most tile in the row, right doesn't get rendered
                            state.tileGrid[val[5] - 1][4] = true            #Why the order value is amazing
                            state.tileCords[val[5] - 1][4] = true
                        end
                        unless state.tileGrid[val[5]][1] == state.quantity - 1     #Same but left side
                            state.tileGrid[val[5] + state.quantity][3] = true
                            state.tileCords[val[5] + state.quantity][3] = true
                        end
                    elsif state.mode == :insert
                        #adds the current sprite value selected to tileCords. (changes from the -1 earlier)
                        val[6] = rand(state.spriteSelection.length)
                    end
                end
            end
        end
    end

    def switchModes
        #Switches between insert and delete modes
        if inputs.keyboard.key_up.i && state.mode == :delete
            state.mode = :insert
            inputs.keyboard.clear
        elsif inputs.keyboard.key_up.d && state.mode == :insert
            state.mode = :delete
            inputs.keyboard.clear
        end
    end

end

$isometric = Isometric.new

def tick args
    $isometric.grid    = args.grid
    $isometric.inputs  = args.inputs
    $isometric.state   = args.state
    $isometric.outputs = args.outputs
    $isometric.tick
end

    Genre Rpg Topdown link

    Topdown Casino - main.rb link

    # ./samples/99_genre_rpg_topdown/topdown_casino/app/main.rb
$gtk.reset

def coinflip
  rand < 0.5
end

class Game
  attr_accessor :args

  def text_font
    return nil #"rpg.ttf"
  end

  def text_color
    [ 255, 255, 255, 255 ]
  end

  def set_gem_values
    @args.state.gem0 = ((coinflip) ?  100 : 20)
    @args.state.gem1 = ((coinflip) ? -10 : -50)
    @args.state.gem2 = ((coinflip) ? -10 : -30)
    if coinflip
      tmp = @args.state.gem0
      @args.state.gem0 = @args.state.gem1
      @args.state.gem1 = tmp
    end
    if coinflip
      tmp = @args.state.gem1
      @args.state.gem1 = @args.state.gem2
      @args.state.gem2 = tmp
    end
    if coinflip
      tmp = @args.state.gem0
      @args.state.gem0 = @args.state.gem2
      @args.state.gem2 = tmp
    end
  end

  def initialize args
    @args = args
    @args.state.animticks = 0
    @args.state.score = 0
    @args.state.gem_chosen = false
    @args.state.round_finished = false
    @args.state.gem0_x = 197
    @args.state.gem0_y = 720-274
    @args.state.gem1_x = 623
    @args.state.gem1_y = 720-274
    @args.state.gem2_x = 1049
    @args.state.gem2_y = 720-274
    @args.state.hero_sprite = "sprites/herodown100.png"
    @args.state.hero_x = 608
    @args.state.hero_y = 720-656
    @args.state.hero.sprite ||= []
    set_gem_values
  end

  def render_gem_value x, y, gem
    if @args.state.gem_chosen
      @args.outputs.labels << [ x, y + 96, gem.to_s, 1, 1, *text_color, text_font ]
    end
  end

  def render
    gemsprite = ((@args.state.animticks % 400) < 200) ? 'sprites/gem200.png' : 'sprites/gem400.png'
    @args.outputs.background_color = [ 0, 0, 0, 255 ]
    @args.outputs.sprites << [608, 720-150, 64, 64, 'sprites/oldman.png']
    @args.outputs.sprites << [300, 720-150, 64, 64, 'sprites/fire.png']
    @args.outputs.sprites << [900, 720-150, 64, 64, 'sprites/fire.png']
    @args.outputs.sprites << [@args.state.gem0_x, @args.state.gem0_y, 32, 64, gemsprite]
    @args.outputs.sprites << [@args.state.gem1_x, @args.state.gem1_y, 32, 64, gemsprite]
    @args.outputs.sprites << [@args.state.gem2_x, @args.state.gem2_y, 32, 64, gemsprite]
    @args.outputs.sprites << [@args.state.hero_x, @args.state.hero_y, 64, 64, @args.state.hero_sprite]

    @args.outputs.labels << [ 630, 720-30, "IT'S A SECRET TO EVERYONE.", 1, 1, *text_color, text_font ]
    @args.outputs.labels << [ 50, 720-85, @args.state.score.to_s, 1, 1, *text_color, text_font ]
    render_gem_value @args.state.gem0_x, @args.state.gem0_y, @args.state.gem0
    render_gem_value @args.state.gem1_x, @args.state.gem1_y, @args.state.gem1
    render_gem_value @args.state.gem2_x, @args.state.gem2_y, @args.state.gem2
  end

  def calc
    @args.state.animticks += 16

    return unless @args.state.gem_chosen
    @args.state.round_finished_debounce ||= 60 * 3
    @args.state.round_finished_debounce -= 1
    return if @args.state.round_finished_debounce > 0

    @args.state.gem_chosen = false
    @args.state.hero.sprite[0] = 'sprites/herodown100.png'
    @args.state.hero.sprite[1] = 608
    @args.state.hero.sprite[2] = 656
    @args.state.round_finished_debounce = nil
    set_gem_values
  end

  def walk xdir, ydir, anim
    @args.state.hero_sprite = "sprites/#{anim}#{(((@args.state.animticks % 200) < 100) ? '100' : '200')}.png"
    @args.state.hero_x += 5 * xdir
    @args.state.hero_y += 5 * ydir
  end

  def check_gem_touching gem_x, gem_y, gem
    return if @args.state.gem_chosen
    herorect = [ @args.state.hero_x, @args.state.hero_y, 64, 64 ]
    return if !herorect.intersect_rect?([gem_x, gem_y, 32, 64])
    @args.state.gem_chosen = true
    @args.state.score += gem
    @args.outputs.sounds << ((gem < 0) ? 'sounds/lose.wav' : 'sounds/win.wav')
  end

  def input
    if @args.inputs.keyboard.key_held.left
      walk(-1.0, 0.0, 'heroleft')
    elsif @args.inputs.keyboard.key_held.right
      walk(1.0, 0.0, 'heroright')
    elsif @args.inputs.keyboard.key_held.up
      walk(0.0, 1.0, 'heroup')
    elsif @args.inputs.keyboard.key_held.down
      walk(0.0, -1.0, 'herodown')
    end

    check_gem_touching(@args.state.gem0_x, @args.state.gem0_y, @args.state.gem0)
    check_gem_touching(@args.state.gem1_x, @args.state.gem1_y, @args.state.gem1)
    check_gem_touching(@args.state.gem2_x, @args.state.gem2_y, @args.state.gem2)
  end

  def tick
    input
    calc
    render
  end
end

def tick args
    args.state.game ||= Game.new args
    args.state.game.args = args
    args.state.game.tick
end

    Topdown Starting Point - main.rb link

    # ./samples/99_genre_rpg_topdown/topdown_starting_point/app/main.rb
=begin
 APIs listing that haven't been encountered in previous sample apps:

 - reverse: Returns a new string with the characters from original string in reverse order.
   For example, the command "dragonruby".reverse would return the string "yburnogard".
   Reverse is not only limited to strings, but can be applied to arrays and other collections.

 Reminders:

 - HASH#intersect_rect?: Returns true or false depending on if two rectangles intersect.

 - args.outputs.labels: Added a hash to this collection will generate a label.
   The parameters are:
   {
     x: X,
     y: y,
     text: TEXT,
     size_px: 22 (optional),
     anchor_x: 0 (optional),
     anchor_y: 0 (optional),
     r: RED (optional),
     g: GREEN (optional),
     b: BLUE (optional),
     a: ALPHA (optional),
     font: PATH_TO_TTF (optional)
   }
=end

# This code shows a maze and uses input from the keyboard to move the user around the screen.
# The objective is to reach the goal.

# Sets values of tile size and player's movement speed
# Also creates tile or box for player and generates map
def tick args
  args.state.tile_size     = 80
  args.state.player_speed  = 4
  args.state.player      ||= tile(args, 7, 3, 0, 128, 180)
  generate_map args

  # Adds walls, goal, and player to args.outputs.solids so they appear on screen
  args.outputs.sprites << args.state.walls
  args.outputs.sprites << args.state.goal
  args.outputs.sprites << args.state.player

  # If player's box intersects with goal, a label is output onto the screen
  if args.state.player.intersect_rect? args.state.goal
    args.outputs.labels << { x: 30, y: 720 - 30, text: "You're a wizard Harry!!" } # 30 pixels lower than top of screen
  end

  move_player args, -1,  0 if args.inputs.keyboard.left # x position decreases by 1 if left key is pressed
  move_player args,  1,  0 if args.inputs.keyboard.right # x position increases by 1 if right key is pressed
  move_player args,  0,  1 if args.inputs.keyboard.up # y position increases by 1 if up is pressed
  move_player args,  0, -1 if args.inputs.keyboard.down # y position decreases by 1 if down is pressed
end

# Sets position, size, and color of the tile
def tile args, x, y, r, g, b
  {
    x: x * args.state.tile_size, # sets definition for array using method parameters
    y: y * args.state.tile_size, # multiplying by tile_size sets x and y to correct position using pixel values
    w: args.state.tile_size,
    h: args.state.tile_size,
    path: :pixel,
    r: r,
    g: g,
    b: b
  }
end

# Creates map by adding tiles to the wall, as well as a goal (that the player needs to reach)
def generate_map args
  return if args.state.area

  # Creates the area of the map. There are 9 rows running horizontally across the screen
  # and 16 columns running vertically on the screen. Any spot with a "1" is not
  # open for the player to move into (and is green), and any spot with a "0" is available
  # for the player to move in.
  args.state.area = [
    [1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
    [1, 1, 1, 2, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1,], # the "2" represents the goal
    [1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,],
    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 ],
  ].reverse # reverses the order of the area collection

  # By reversing the order, the way that the area appears above is how it appears
  # on the screen in the game. If we did not reverse, the map would appear inverted.

  #The wall starts off with no tiles.
  args.state.walls = []

  # If v is 1, a green tile is added to args.state.walls.
  # If v is 2, a black tile is created as the goal.
  args.state.area.map_2d do |y, x, v|
    if    v == 1
      args.state.walls << tile(args, x, y, 0, 255, 0) # green tile
    elsif v == 2 # notice there is only one "2" above because there is only one single goal
      args.state.goal   = tile(args, x, y, 0,   0, 0) # black tile
    end
  end
end

# Allows the player to move their box around the screen
def move_player args, vector_x, vector_y
  player = args.state.player
  next_x = player.x + vector_x * args.state.player_speed
  next_y = player.y + vector_y * args.state.player_speed
  next_position = args.state.player.merge x: next_x, y: next_y

  # If the player's box hits a wall, it is not able to move further in that direction
  return if next_x < 0 || (next_x + player.w) > 1280
  return if next_y < 0 || (next_y + player.h) > 720
  return if args.state.walls.any_intersect_rect? next_position

  # Player's box is able to move at angles (not just the four general directions) fast
  args.state.player.x = next_x
  args.state.player.y = next_y
end

    Genre Rpg Turn Based link

    Turn Based Battle - main.rb link

    # ./samples/99_genre_rpg_turn_based/turn_based_battle/app/main.rb
def tick args
  args.state.phase ||= :selecting_top_level_action
  args.state.potential_action ||= :attack
  args.state.currently_acting_hero_index ||= 0
  args.state.enemies ||= [
    { name: "Goblin A" },
    { name: "Goblin B" },
    { name: "Goblin C" }
  ]

  args.state.heroes ||= [
    { name: "Hero A" },
    { name: "Hero B" },
    { name: "Hero C" }
  ]

  args.state.potential_enemy_index ||= 0

  if args.state.phase == :selecting_top_level_action
    if args.inputs.keyboard.key_down.down
      case args.state.potential_action
      when :attack
        args.state.potential_action = :special
      when :special
        args.state.potential_action = :magic
      when :magic
        args.state.potential_action = :items
      when :items
        args.state.potential_action = :items
      end
    elsif args.inputs.keyboard.key_down.up
      case args.state.potential_action
      when :attack
        args.state.potential_action = :attack
      when :special
        args.state.potential_action = :attack
      when :magic
        args.state.potential_action = :special
      when :items
        args.state.potential_action = :magic
      end
    end

    if args.inputs.keyboard.key_down.enter
      args.state.selected_action = args.state.potential_action
      args.state.next_phase = :selecting_target
    end
  end

  if args.state.phase == :selecting_target
    if args.inputs.keyboard.key_down.left
      select_previous_live_enemy args
    elsif args.inputs.keyboard.key_down.right
      select_next_live_enemy args
    end

    args.state.potential_enemy_index = args.state.potential_enemy_index.clamp(0, args.state.enemies.length - 1)

    if args.inputs.keyboard.key_down.enter
      args.state.enemies[args.state.potential_enemy_index].dead = true
      args.state.potential_enemy_index = args.state.enemies.find_index { |e| !e.dead }
      args.state.selected_action = nil
      args.state.potential_action = :attack
      args.state.next_phase = :selecting_top_level_action
      args.state.currently_acting_hero_index += 1
      if args.state.currently_acting_hero_index >= args.state.heroes.length
        args.state.currently_acting_hero_index = 0
      end
    end
  end

  if args.state.next_phase
    args.state.phase = args.state.next_phase
    args.state.next_phase = nil
  end

  render_actions_menu args
  render_enemies args
  render_heroes args
  render_hero_statuses args
end

def select_next_live_enemy args
  next_target_index = args.state.enemies.find_index.with_index { |e, i| !e.dead && i > args.state.potential_enemy_index }
  if next_target_index
    args.state.potential_enemy_index = next_target_index
  end
end

def select_previous_live_enemy args
  args.state.potential_enemy_index -= 1
  if args.state.potential_enemy_index < 0
    args.state.potential_enemy_index = 0
  elsif args.state.enemies[args.state.potential_enemy_index].dead
    select_previous_live_enemy args
  end
end

def render_actions_menu args
  args.outputs.borders << args.layout.rect(row:  8, col: 0, w: 4, h: 4, include_row_gutter: true, include_col_gutter: true)
  if !args.state.selected_action
    selected_rect = if args.state.potential_action == :attack
                      args.layout.rect(row:  8, col: 0, w: 4, h: 1)
                    elsif args.state.potential_action == :special
                      args.layout.rect(row:  9, col: 0, w: 4, h: 1)
                    elsif args.state.potential_action == :magic
                      args.layout.rect(row: 10, col: 0, w: 4, h: 1)
                    elsif args.state.potential_action == :items
                      args.layout.rect(row: 11, col: 0, w: 4, h: 1)
                    end

    args.outputs.solids  << selected_rect.merge(r: 200, g: 200, b: 200)
  end

  args.outputs.borders << args.layout.rect(row:  8, col: 0, w: 4, h: 1)
  args.outputs.labels  << args.layout.rect(row:  8, col: 0, w: 4, h: 1).center.merge(text: "Attack", vertical_alignment_enum: 1, alignment_enum: 1)

  args.outputs.borders << args.layout.rect(row:  9, col: 0, w: 4, h: 1)
  args.outputs.labels  << args.layout.rect(row:  9, col: 0, w: 4, h: 1).center.merge(text: "Special", vertical_alignment_enum: 1, alignment_enum: 1)

  args.outputs.borders << args.layout.rect(row: 10, col: 0, w: 4, h: 1)
  args.outputs.labels  << args.layout.rect(row: 10, col: 0, w: 4, h: 1).center.merge(text: "Magic", vertical_alignment_enum: 1, alignment_enum: 1)

  args.outputs.borders << args.layout.rect(row: 11, col: 0, w: 4, h: 1)
  args.outputs.labels  << args.layout.rect(row: 11, col: 0, w: 4, h: 1).center.merge(text: "Items", vertical_alignment_enum: 1, alignment_enum: 1)
end

def render_enemies args
  args.outputs.primitives << args.state.enemies.map_with_index do |e, i|
    if e.dead
      nil
    elsif i == args.state.potential_enemy_index && args.state.phase == :selecting_target
      [
        args.layout.rect(row: 1, col: 9 + i * 2, w: 2, h: 2).solid!(r: 200, g: 200, b: 200),
        args.layout.rect(row: 1, col: 9 + i * 2, w: 2, h: 2).border!,
        args.layout.rect(row: 1, col: 9 + i * 2, w: 2, h: 2).center.label!(text: "#{e.name}", vertical_alignment_enum: 1, alignment_enum: 1)
      ]
    else
      [
        args.layout.rect(row: 1, col: 9 + i * 2, w: 2, h: 2).border!,
        args.layout.rect(row: 1, col: 9 + i * 2, w: 2, h: 2).center.label!(text: "#{e.name}", vertical_alignment_enum: 1, alignment_enum: 1)
      ]
    end
  end
end

def render_heroes args
  args.outputs.primitives << args.state.heroes.map_with_index do |h, i|
    if i == args.state.currently_acting_hero_index
      [
        args.layout.rect(row: 5, col: 9 + i * 2, w: 2, h: 2).solid!(r: 200, g: 200, b: 200),
        args.layout.rect(row: 5, col: 9 + i * 2, w: 2, h: 2).border!,
        args.layout.rect(row: 5, col: 9 + i * 2, w: 2, h: 2).center.label!(text: "#{h.name}", vertical_alignment_enum: 1, alignment_enum: 1)
      ]
    else
      [
        args.layout.rect(row: 5, col: 9 + i * 2, w: 2, h: 2).border!,
        args.layout.rect(row: 5, col: 9 + i * 2, w: 2, h: 2).center.label!(text: "#{h.name}", vertical_alignment_enum: 1, alignment_enum: 1)
      ]
    end
  end
end

def render_hero_statuses args
  args.outputs.borders << args.layout.rect(row: 8, col: 4, w: 20, h: 4, include_col_gutter: true, include_row_gutter: true)
end

$gtk.reset

    Genre Simulation link

    Sand main.rb link

    # ./samples/99_genre_simulation/sand_simulation/app/main.rb
class Elements
  def initialize size
    @size = size
    @max_x_ordinal = 1280.idiv size
    @element_lookup = {}
    @elements = []
  end

  def add_element x_ordinal, y_ordinal
    return nil if @element_lookup.dig x_ordinal, y_ordinal
    element = Element.new x_ordinal, y_ordinal, @size
    @elements << element
    rehash_elements
    element
  end

  def tick
    fn.each_send @elements, self, :move_element
    rehash_elements
  end

  def move_element element
    if below_empty?(element) && element.y_ordinal != 0
      element.move  0, -1
    elsif below_left_empty?(element) && element.y_ordinal != 0 && element.x_ordinal != 0
      element.move -1, -1
    elsif below_right_empty?(element) && element.y_ordinal != 0 && element.x_ordinal != @max_x_ordinal
      element.move  1, -1
    end
  end

  def element_count
    @elements.length
  end

  def rehash_elements
    @element_lookup.clear
    fn.each_send @elements, self, :rehash_element
  end

  def rehash_element element
    @element_lookup[element.x_ordinal] ||= {}
    @element_lookup[element.x_ordinal][element.y_ordinal] = element
  end

  def below_empty? e
    return false if e.y_ordinal == 0
    return true  if !@element_lookup[e.x_ordinal]
    return true  if !@element_lookup[e.x_ordinal][e.y_ordinal - 1]
    return false if  @element_lookup[e.x_ordinal][e.y_ordinal - 1]
    return true
  end

  def below_left_empty? e
    return false if e.y_ordinal == 0
    return false if e.x_ordinal == 0
    return true  if !@element_lookup[e.x_ordinal - 1]
    return true  if !@element_lookup[e.x_ordinal - 1][e.y_ordinal - 1]
    return false if  @element_lookup[e.x_ordinal - 1][e.y_ordinal - 1]
    return true
  end

  def below_right_empty? e
    return false if e.y_ordinal == 0
    return false if e.x_ordinal == 256
    return true  if !@element_lookup[e.x_ordinal + 1]
    return true  if !@element_lookup[e.x_ordinal + 1][e.y_ordinal - 1]
    return false if  @element_lookup[e.x_ordinal + 1][e.y_ordinal - 1]
    return true
  end
end

class Element
  attr_sprite
  attr :x_ordinal, :y_ordinal

  def initialize x_ordinal, y_ordinal, s
    @x_ordinal     = x_ordinal
    @y_ordinal     = y_ordinal
    @s             = s
    @x             = x_ordinal * s
    @y             = y_ordinal * s
    @w             = s
    @h             = s
    @path          = "sprites/sand-element.png"
  end

  def draw_override ffi
    ffi.draw_sprite @x, @y, @w, @h, @path
  end

  def move dx, dy
    @y_ordinal += dy
    @x_ordinal += dx
    @y = @y_ordinal * @s
    @x = @x_ordinal * @s
  end
end

def tick args
  args.state.size        ||= 10
  args.state.mouse_state ||= :up
  @elements              ||= Elements.new args.state.size

  if args.inputs.mouse.down
    args.state.mouse_state = :held
  elsif args.inputs.mouse.up
    args.state.mouse_state = :released
  end

  if args.state.mouse_state == :held
    added = @elements.add_element args.inputs.mouse.x.idiv(args.state.size), args.inputs.mouse.y.idiv(args.state.size)
    args.outputs.static_sprites << added if added
  end

  @elements.tick

  args.outputs.labels << { x: 30, y: 30.from_top, text: "#{args.gtk.current_framerate.to_sf}" }
  args.outputs.labels << { x: 30, y: 60.from_top, text: "#{@elements.element_count}" }
end

$gtk.reset
@elements = nil

    Genre Twenty Second Games link

    Twenty Second Starting Point - main.rb link

    # ./samples/99_genre_twenty_second_games/twenty_second_starting_point/app/main.rb
# full documenation is at http://docs.dragonruby.org
# be sure to come to the discord if you hit any snags: http://discord.dragonruby.org
def tick args
  # ====================================================
  # initialize default variables
  # ====================================================

  # ruby has an operator called ||= which means "only initialize this if it's nil"
  args.state.count_down   ||= 20 * 60 # set the count down to 20 seconds
  # set the initial position of the target
  args.state.target       ||= { x: args.grid.w.half,
                                y: args.grid.h.half,
                                w: 20,
                                h: 20 }

  # set the initial position of the player
  args.state.player       ||= { x: 50,
                                y: 50,
                                w: 20,
                                h: 20 }

  # set the player movement speed
  args.state.player_speed ||= 5

  # set the score
  args.state.score        ||= 0
  args.state.teleports    ||= 3

  # set the instructions
  args.state.instructions ||= "Get to the red goal! Use arrow keys to move. Spacebar to teleport (use them carefully)!"

  # ====================================================
  # render the game
  # ====================================================
  args.outputs.labels  << { x: args.grid.w.half, y: args.grid.h - 10,
                            text: args.state.instructions,
                            alignment_enum: 1 }

  # check if it's game over. if so, then render game over
  # otherwise render the current time left
  if game_over? args
    args.outputs.labels  << { x: args.grid.w.half,
                              y: args.grid.h - 40,
                              text: "game over! (press r to start over)",
                              alignment_enum: 1 }
  else
    args.outputs.labels  << { x: args.grid.w.half,
                              y: args.grid.h - 40,
                              text: "time left: #{(args.state.count_down.idiv 60) + 1}",
                              alignment_enum: 1 }
  end

  # render the score
  args.outputs.labels  << { x: args.grid.w.half,
                            y: args.grid.h - 70,
                            text: "score: #{args.state.score}",
                            alignment_enum: 1 }

  # render the player with teleport count
  args.outputs.sprites << { x: args.state.player.x,
                            y: args.state.player.y,
                            w: args.state.player.w,
                            h: args.state.player.h,
                            path: 'sprites/square-green.png' }

  args.outputs.labels << { x: args.state.player.x + 10,
                           y: args.state.player.y + 40,
                           text: "teleports: #{args.state.teleports}",
                           alignment_enum: 1, size_enum: -2 }

  # render the target
  args.outputs.sprites << { x: args.state.target.x,
                            y: args.state.target.y,
                            w: args.state.target.w,
                            h: args.state.target.h,
                            path: 'sprites/square-red.png' }

  # ====================================================
  # run simulation
  # ====================================================

  # count down calculation
  args.state.count_down -= 1
  args.state.count_down = -1 if args.state.count_down < -1

  # ====================================================
  # process player input
  # ====================================================
  # if it isn't game over let them move
  if !game_over? args
    dir_y = 0
    dir_x = 0

    # determine the change horizontally
    if args.inputs.keyboard.up
      dir_y += args.state.player_speed
    elsif args.inputs.keyboard.down
      dir_y -= args.state.player_speed
    end

    # determine the change vertically
    if args.inputs.keyboard.left
      dir_x -= args.state.player_speed
    elsif args.inputs.keyboard.right
      dir_x += args.state.player_speed
    end

    # determine if teleport can be used
    if args.inputs.keyboard.key_down.space && args.state.teleports > 0
      args.state.teleports -= 1
      dir_x *= 20
      dir_y *= 20
    end

    # apply change to player
    args.state.player.x += dir_x
    args.state.player.y += dir_y
  else
    # if r is pressed, reset the game
    if args.inputs.keyboard.key_down.r
      $gtk.reset
      return
    end
  end

  # ====================================================
  # determine score
  # ====================================================

  # calculate new score if the player is at goal
  if !game_over? args

    # if the player is at the goal, then move the goal
    if args.state.player.intersect_rect? args.state.target
      # increment the goal
      args.state.score += 1

      # move the goal to a random location
      args.state.target = { x: (rand args.grid.w), y: (rand args.grid.h), w: 20, h: 20 }

      # make sure the goal is inside the view area
      if args.state.target.x < 0
        args.state.target.x += 20
      elsif args.state.target.x > 1280
        args.state.target.x -= 20
      end

      # make sure the goal is inside the view area
      if args.state.target.y < 0
        args.state.target.y += 20
      elsif args.state.target.y > 720
        args.state.target.y -= 20
      end
    end
  end
end

def game_over? args
  args.state.count_down < 0
end

$gtk.reset