Gosu + Chipmunk

gosu_chipmunk_sample2.rb

require 'gosu'
require 'rmagick'
require 'chipmunk'

Width, Height = 600, 600
Wall_h = 20

class MyWindow < Gosu::Window
  def initialize
    super Width, Height, false
    self.caption = "Gosu + Chipmunk"
    
    @space = CP::Space.new
    @space.gravity = CP::Vec2.new(0, 250)
    
    circle_image = Magick::Image.new(21, 21) {self.background_color = 'transparent'}
    gc = Magick::Draw.new
    gc.fill('yellow')
    gc.circle(10, 10, 0, 10)
    gc.draw(circle_image)
    @circle = Gosu::Image.new(circle_image)
    
    background = Magick::Image.new(Width, Height) {self.background_color = "black"}
    create_wall(0, Height - Wall_h, Width, Height - Wall_h, Wall_h, background)
    create_wall(Wall_h, 0, Wall_h, Height, Wall_h, background)
    create_wall(Width, 0, Width, Height, Wall_h, background)
    create_wall(120, 150, 400, 200, Wall_h, background)
    create_wall(200, 450, 480, 400, Wall_h, background)
    @background_image = Gosu::Image.new(background)
    
    @circles = []
  end
  
  def create_circle
    body = CP::Body.new(1, CP::INFINITY)
    body.p = CP::Vec2.new(rand(Width / 2 + Width / 4), -20)
    body.v = CP::Vec2.new(rand * 500 - 250, 0)
    shape = CP::Shape::Circle.new(body, 10, CP::Vec2.new(0, 0))
    shape.e = 0.8
    shape.u = 0
    
    @space.add_body(body)
    @space.add_shape(shape)
    
    body
  end
  
  def create_wall(x1, y1, x2, y2, height, bg)
    sb = CP::Body.new_static
    p1 = CP::Vec2.new(x1, y1)
    p4 = CP::Vec2.new(x2, y2)
    p0 = p4 - p1
    p2 = p1 + p0.normalize.rotate(CP::Vec2.new(0, 1)) * height
    p3 = p2 + p0
    verts = [p1, p2, p3, p4]
    wshape = CP::Shape::Poly.new(sb, verts, CP::Vec2.new(0, 0))
    wshape.e = 1
    wshape.u = 0
    @space.add_shape(wshape)
    
    gc = Magick::Draw.new
    gc.fill('firebrick')
    verts = verts.map {|vt| [vt.x, vt.y]}.flatten
    gc.polygon(*verts)
    gc.draw(bg)
  end
  
  def update
    @space.step(1.0 / 60)
    @circles << create_circle if rand < 0.1 and @circles.size < 300
  end
  
  def draw
    @background_image.draw(0, 0, 0)
    @circles.each {|c| @circle.draw_rot(c.p.x, c.p.y, 1, 0)}
  end
end

MyWindow.new.show