     ctx.globalCompositeOperation = 'source-over'
     ctx.fillStyle = "rgba(0, 0, 0, 128)"
     ctx.fillRect(0, 0, @canvas.width, @canvas.height)
-    #ctx.clearRect(0, 0, @canvas.width, @canvas.height)
+
     for particle in @particles
       particle.draw(ctx)
 
     window.requestAnimationFrame(@draw)
 
 MOUSE =
-  pos: 
+  pos:
     x: 0
     y: 0
   mass: 1
+
 $ ->
-  MOUSE = 
+  MOUSE =
     pos: new Vector(0, 0)
     mass: 1
   animator = new Animator($("canvas"))

    ctx.restore()

class Animator
  MS_PER_TICK: 1000 / 120.0
  constructor: (canvas) ->
    @$canvas = canvas

      @vel.y = -@vel.y * 0.5

  draw: (ctx) =>
    ### Draw this Particle using the context <ctx>. ###
    ctx.save()
    ctx.beginPath()

