/// <summary>
 /// 轮询。
 /// </summary>
 void Update()
 {
     // 如果鼠标左键按下
     if (Input.GetMouseButtonDown(0))
     {
         // 获得鼠标的屏幕坐标
         Vector3 mousePosition = Input.mousePosition;
         // 得到鼠标的世界坐标
         Vector3 mouseWorldPosition = Camera.main.ScreenToWorldPoint(mousePosition);
         // 得到鼠标的Tile坐标
         Vector3Int mapCellPosition = m_TileMap.WorldToCell(mouseWorldPosition);
         // 如果该坐标合法(不越界、不是障碍物)
         if (m_AStarUnityTile.CheckValid(mapCellPosition))
         {
             // 如果设置点的机会还剩2次(代表将要设置开始点)
             if (m_SetPointChance == 2)
             {
                 m_StartNode = new AStarNode(mapCellPosition.y, mapCellPosition.x);
                 m_AStarUnityTile.MarkNode(m_StartNode, 3);
             }
             // 否则如果设置点的机会只剩1次(代表将要设置目标点)
             else if (m_SetPointChance == 1)
             {
                 m_EndNode = new AStarNode(mapCellPosition.y, mapCellPosition.x);
                 m_AStarUnityTile.MarkNode(m_EndNode, 4);
             }
             // 设置后要将机会减一
             m_SetPointChance--;
         }
     }
 }
 public override void Do()
 {
     m_tool.MarkNode(m_actor, 7);
 }