life_glsl.rb

require 'ray'

class Life
  Width  = 1920
  Height = 1080

  Size = Ray::Vector2[Width, Height]

  def initialize
    @image  = Ray::Image.new Size
    @buffer = Ray::Image.new Size

    setup_image(@image)

    @image_sprite  = Ray::Sprite.new(@image)
    @buffer_sprite = Ray::Sprite.new(@buffer)

    @image_target  = Ray::ImageTarget.new(@image)
    @buffer_target = Ray::ImageTarget.new(@buffer)

    setup_target(@image_target)
    setup_target(@buffer_target)
  end

  def update
    @buffer_target.draw @image_sprite
    swap
  end

  def sprite
    @image_sprite
  end

  private
  def swap
    @buffer_target.update

    @image, @buffer = @buffer, @image
    @image_sprite, @buffer_sprite = @buffer_sprite, @image_sprite
    @image_target, @buffer_target = @buffer_target, @image_target
  end

  def setup_image(image)
    image.map! { rand(2).zero? ? Ray::Color.black : Ray::Color.white }
  end

  def setup_target(target)
    target.shader.compile(:frag => StringIO.new(<<eof))
#version 130

const float width  = 1.0 / #{Width.to_f};
const float height = 1.0 / #{Height.to_f};

uniform sampler2D in_Texture;

in  vec2 var_TexCoord;
out vec4 out_FragColor;

bool is_alive(vec2 pos) {
  return texture(in_Texture, var_TexCoord + pos) == vec4(0, 0, 0, 1);
}

int count_neighbours() {
  int count = 0;

  if (is_alive(vec2(-width, +height))) count += 1;
  if (is_alive(vec2(-width, -height))) count += 1;
  if (is_alive(vec2(+width, +height))) count += 1;
  if (is_alive(vec2(+width, -height))) count += 1;

  if (is_alive(vec2(+width, 0)))  count += 1;
  if (is_alive(vec2(-width, 0)))  count += 1;
  if (is_alive(vec2(0, +height))) count += 1;
  if (is_alive(vec2(0, -height))) count += 1;

  return count;
}

void main() {
  int count = count_neighbours();

  if (is_alive(vec2(0, 0))) {
    if (count == 2 || count == 3)
      out_FragColor = vec4(0, 0, 0, 1);
    else
      out_FragColor = vec4(1, 1, 1, 1);
  }
  else if (count == 3)
    out_FragColor = vec4(0, 0, 0, 1);
  else
    out_FragColor = vec4(1, 1, 1, 1);
}
eof
  end
end

Ray.game "The game of life", :size => Life::Size do
  register { add_hook :quit, method(:exit!) }

  scene :life do
    self.frames_per_second = nil

    window.view = Ray::View.new(Life::Size / 2, Life::Size)

    @life = Life.new

    always do
      @life.update
    end

    render do |win|
      win.draw @life.sprite
    end
  end

  scenes << :life
end