       fill:           'rgba(255,0,0,0.5)'
       selectable:     true
       tank_direction: 1
+      tank_turn_cnt:  0
 
   new fabric.Image.fromURL 'tank2.png', (img) ->
     tank2 = img

      fill:           'rgba(0,255,0,0.5)'
      selectable:     false
      tank_direction: 3

  keyboard =
    tank1_left:  false

    keyboard[key] = false

  turn_tank = (tank, offset) ->
    tank.tank_turn_cnt += 1
    if tank.tank_turn_cnt > 20
      tank.tank_turn_cnt = 0
      # See http://javascript.about.com/od/problemsolving/a/modulobug.htm
      tank.tank_direction = (((tank.tank_direction + offset) % 4) + 4) % 4
      tank.setAngle tank.tank_direction * 90

  move_tank = (key_up, key_right, key_down, key_left, tank) ->
    if key_right
