 
   battle_field.add_terrain(HomeTerrain, new MapArea2D(240, 480, 280, 520))
 
+  # set a reference for easier debug
   document.battle_field = battle_field
 
   console.log "init done"

      when 0
        new MapArea2D(@area.x1, @area.y1 - @default_height/4, @area.x2, @area.y1)
      when 90
        new MapArea2D(@area.x2, @area.y1, @area.y2 + @default_width/4, @area.y2)
      when 180
        new MapArea2D(@area.x1, @area.y2, @area.x2, @area.y2 + @default_height/4)
      when 270
        new MapArea2D(@area.x1 - @default_width/4, @area.y1, @area.x1, @area.y2)

class MapUnit2DForStupidTank extends MapUnit2DForTank
  current_frames: () ->

  height: () -> @area.y2 - @area.y1

  destroy: () ->
    @destroy_display()
    @map.delete_map_unit(this)

  destroy_display: () ->
    @display_object.remove()

  accept: (other_unit) -> @model.accept(other_unit.model)

  update: () ->
