Crystal Game Development

cray-test.cr

require "cray"

module CrayTest
  SCREEN_WIDTH  = 1024
  SCREEN_HEIGHT =  768

  LibRay.init_window SCREEN_WIDTH, SCREEN_HEIGHT, "Example: input"

  @@icon = LibRay.load_image File.join(__DIR__, "circle.png")
  @@circle = LibRay.load_texture_from_image(@@icon)

  LibRay.set_window_icon(@@icon)

  @@circle_pos = LibRay::Vector2.new(x: SCREEN_WIDTH/2 - @@circle.width/2, y: SCREEN_HEIGHT/2 - @@circle.height/2)
  @@bullets = [] of LibRay::Vector2
  @@bullet = LibRay::Vector2.new

  SPEED     = 300
  TEXT      = "Use WASD to move the red circle!"
  FONT_SIZE = 20

  def self.input_events
    delta = LibRay.get_frame_time

    if LibRay.key_down? LibRay::KEY_W
      @@circle_pos.y -= delta * SPEED
    end

    if LibRay.key_down? LibRay::KEY_S
      @@circle_pos.y += delta * SPEED
    end

    if LibRay.key_down? LibRay::KEY_A
      @@circle_pos.x -= delta * SPEED
    end

    if LibRay.key_down? LibRay::KEY_D
      @@circle_pos.x += delta * SPEED
    end

    if LibRay.key_released? LibRay::KEY_SPACE
      @@bullets << LibRay::Vector2.new(x: @@circle_pos.x + (@@circle.width / 2), y: @@circle_pos.y - (@@circle.height / 4))
      @@bullet = LibRay::Vector2.new(x: @@circle_pos.x + (@@circle.width / 2), y: @@circle_pos.y - (@@circle.height / 4))
    end
  end

  def self.movement
    delta = LibRay.get_frame_time

    @@bullets.each do |bullet|
      bullet.y -= delta * SPEED
    end

    @@bullet.y -= delta * SPEED
  end

  def self.draw
    LibRay.begin_drawing
    LibRay.clear_background LibRay::BLACK

    LibRay.draw_fps 0, 0

    text_size = LibRay.measure_text(TEXT, FONT_SIZE)
    LibRay.draw_text(
      TEXT,
      SCREEN_WIDTH - text_size,
      0,
      FONT_SIZE,
      LibRay::GREEN
    )

    # draw circle
    LibRay.draw_texture_v(@@circle, @@circle_pos, LibRay::WHITE)

    # draw bullets
    @@bullets.each do |bullet|
      LibRay.draw_rectangle(bullet.x, bullet.y, 3, 10, LibRay::GREEN)
    end
    LibRay.draw_rectangle(@@bullet.x, @@bullet.y, 3, 10, LibRay::GREEN)

    LibRay.end_drawing
  end

  def self.application_loop
    while !LibRay.window_should_close?
      input_events()
      movement()
      draw()
    end
  end

  def self.run
    application_loop()
    LibRay.unload_texture(@@circle)
    LibRay.close_window
  end
end

CrayTest.run

crystal-game-dev.md

Intro to Crystal Game Development

asdf version manager

Crystal versioning like rbenv, to switch Crystal versions between directories. Not necessary, but thought it would be good to set up in case the Crystal version I try gets out of date soon.

https://asdf-vm.com/#/core-manage-asdf-vm

Once asdf is installed, you can list all available Crystal versions and install one:

$ asdf list-all crystal
# lists all crystal vers available

$ asdf install crystal 0.27.2

# once we create a new project we'll use
$ asdf local crystal 0.27.2

# to set the local crystal version or use `global` to set for everything

init Crystal app

$ crystal init app cray-test

add cray dependency

follow https://gitlab.com/Zatherz/cray to cray dependency:

Add this to your application's shard.yml:

dependencies:
  cray:
    gitlab: zatherz/cray

then run

$ shards install

to install the newly added cray dependency.

install raylib via Homebrew

see https://github.com/raysan5/raylib/wiki/Working-on-macOS

$ brew install raylib

run via:

$ crystal run src/hello_world.cr

(copied hello_world.cr from the examples folder of the cray github: https://gitlab.com/Zatherz/cray

Compiling not working. Difficulties in communicating via Raylib to crystal, maybe the binaries are not matched correctly?

15:34:36 ~/code/crystal/cray-test (master)✗ $ crystal build src/examples/hello-world.cr
Undefined symbols for architecture x86_64:
  "_GetDefaultFont", referenced from:
      ___crystal_main in _main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Error: execution of command failed with code: 1: `cc "${@}" -o '/Users/matt/code/crystal/cray-test/hello-world'  -rdynamic  -L/usr/local/Cellar/raylib/2.0.0/lib -lraylib -lpcre -lgc -lpthread /usr/local/Cellar/crystal/0.27.2/src/ext/libcrystal.a -levent -liconv -ldl -L/usr/lib -L/usr/local/lib`

switched to glove game lib to see if that would work

https://github.com/ddfreyne/glove

Examples: https://github.com/ddfreyne/inari

made a new app, and copied the example code in for displaying a card (image texture):

require "glove"

if full_path = Process.executable_path
  Dir.cd(File.dirname(full_path))
end

card =
  Glove::Entity.new.tap do |e|
    e << Glove::Components::Texture.new("assets/card.png")
    e << Glove::Components::Transform.new.tap do |t|
      t.width = 140_f32
      t.height = 190_f32
      t.translate_x = 400_f32
      t.translate_y = 300_f32
    end
  end

scene =
  Glove::Scene.new.tap do |scene|
    scene.spaces << Glove::Space.new.tap do |space|
      space.entities << card
    end
  end

game = Glove::EntityApp.new(800, 600, "Inari")
game.clear_color = Glove::Color::WHITE
game.replace_scene(scene)
game.run

Glove requires copying over shader files, and any assets, so I reused/modified the Makefile structure from https://github.com/ddfreyne/inari so just with

$ make
$ cd dist/releases/cli
$ ./glove-test

the app opens in a new window, displaying the card image!

I didn't end up liking the Glove library structure too much, so tried going back to Cray, and was successful

back to Cray

Turns out the bindings to Crystal, the get_default_font wasn't working, so I removed the usage of the fonts and switched to use the RayLib methods that don't specify font, and use the default Cray font.