 
     rotation += ROTATE_SPEED * deltaTime if Keyboard.isDown 69
     rotation -= ROTATE_SPEED * deltaTime if Keyboard.isDown 81
+    scale *= 1 + SCALE_SPEED * deltaTime if Keyboard.isDown 88
+    scale /= 1 + SCALE_SPEED * deltaTime if Keyboard.isDown 90
 
     ctx.clearRect 0, 0, width, height
     ctx.translate width/2, height/2

      timeScale *= TIME_SCALE_SPEED
    if e.keyCode == 189
      timeScale /= TIME_SCALE_SPEED
    if e.keyCode == 88
      scale *= SCALE_SPEED
    if e.keyCode == 90
      scale /= SCALE_SPEED
    if e.keyCode == 37 || e.keyCode == 65
      offset = offset.add new Vector(PAN_SPEED, 0)
    if e.keyCode == 38 || e.keyCode == 87

  MAX_MASS = 10
  PAN_SPEED = 10
  ROTATE_SPEED = 0.001
  SCALE_SPEED = 0.001
  TIME_SCALE_SPEED = 1.1

  width = window.innerWidth
