public void OnStaticObjectCreated(StaticObject obj)
{
GameObject obj_go = new GameObject();
obj_go.name = "obj_" + obj.ObjectType;
staticObjGameobjectMap.Add(obj, obj_go);
obj_go.transform.position = new Vector3(obj.Tile.X, obj.Tile.Y, -2);
obj_go.transform.SetParent(this.transform, true);
//FIXME: assume the object must be a wall so we use harcoded wall sprite
obj_go.AddComponent <SpriteRenderer> ().sprite = GetSpriteForStaticObject(obj);
obj.RegisterOnChangedCallBack(OnStaticObjChanged);
}