08_geometry.cr

require "../sdl"

SDL.init(SDL::Init::VIDEO)
at_exit { SDL.quit }

window = SDL::Window.new("SDL tutorial", 640, 480)
renderer = SDL::Renderer.new(window)

width, height = window.size

loop do
  case event = SDL::Event.wait
  when SDL::Event::Quit
    break
  end

  # clear screen in white
  renderer.draw_color = SDL::Color[255, 255, 255, 255]
  renderer.clear

  # centered red rectangle
  renderer.draw_color = SDL::Color[255, 0, 0, 255]
  renderer.fill_rect(width / 4, height / 4, width / 2, height / 2)

  # outlined green rectangle
  renderer.draw_color = SDL::Color[0, 255, 0, 255]
  renderer.draw_rect(width / 6, height / 6, width * 2 / 3, height * 2 / 3)

  # blue horizontal line
  renderer.draw_color = SDL::Color[0, 0, 255, 255]
  renderer.draw_line(0, height / 2, width, height / 2)

  # vertical line of yellow dots
  renderer.draw_color = SDL::Color[255, 255, 0, 255]
  0.step(by: 4, to: height) do |i|
    renderer.draw_point(width / 2, i)
  end

  renderer.present
end