$dimensions = 600
PI=3.141592653

def deg2rad deg
  deg/180.0*PI
end

class Actor
  attr_accessor :offscreen

  def initialize(x,y,dir,v)
    @x=x;
    @y=y;
    @d=dir;
    @v=v;
    self.color(rand(255),rand(255),rand(255))
  end

  def draw
    $app.fill @color
    $app.oval(@x-10.round,@y-10.round,20,20) unless @offscreen || @y<10 || @x<10
  end

  def color r,g,b
    @color=rgb(r,g,b)
  end

  def tick
    return if @offscreen

    @x+= @v * Math.cos(@d)
    @y+= -@v * Math.sin(@d)

    if  @x < 0 || @x > 620 ||
        @y < 0 || @y > 620
      @offscreen=true
    end

    if @x>450 && @x<460
      if -(Math.sin(@d)) < 0
        @d+=PI
      else
        @d-=PI
      end
    end
  end

  def to_s
    "(#{@x},#{@y}) #{@v} -> #{@d}"
  end
end

Shoes.app :width => 600, :height => 600, :title => "Clogs" do
  $app = self

  actors=[]

  5.times do
    actors.push(Actor.new(300,300,deg2rad(rand(360)),rand(5)+1))
  end

  animate(30) do
    clear do
      actors.each do |actor|
        actor.tick
        actor.draw
      end
    end
  end

  animate(1) do
    actors=actors.delete_if do |_|
      _.offscreen
    end
  end
  
  startx=0;starty=0;

  click do |btn,x,y|
    startx=x;starty=y
  end

########## important bit ##########
  release do |btn,x,y|
    dx=x-startx;dy=y-starty
    h=Math.sqrt(dx*dx+dy*dy)

    if dx==0 && dy==0
      dir=deg2rad(rand(360))
    elsif dx==0
      dir=PI/2 if dy<0
      dir=-PI/2 if dy>0
    elsif dx<0
      dir=Math.atan(-(dy.to_f)/(dx.to_f))+3.141592653
    else
      dir=Math.atan(-(dy.to_f)/(dx.to_f))
    end

    if(dx==0 && dy==0)
      v=1
    else
      v=h/10
    end

    puts "dx: #{dx}, dy: #{dy} -> #{dir}"

    actor=Actor.new(startx,starty,dir,v)
    actors.push(actor)    
  end
########## End important bit ##########
end