int TEST = 0;

    // Returns true if you were able to move, false if you collided.
    // 人物不断尝试往‘下‘走到 Y+amount
    //  如果 中途碰撞到物体 则 人物站在 物体上 并return false
    //  否则返回true，代表人物已成功移动到yVel 的位置
    bool TryMoveY(float amount)
    {
        //optimize

        var sign = Mathf.Sign(amount);
        var increment = 0.001f;
        var progress = 0f;

        //var DEBUG = 0;
        TEST = 0;
        while (true)
        {
            //DEBUG++;
            ++TEST;
            var rest = Mathf.Abs(amount) - Mathf.Abs(progress);
            if (rest <= 0)
                break;
            increment = Mathf.Min(increment, rest);

            Y += increment * sign;
            progress += increment * sign;
            if (Colliding())
            {
                Y -= increment * sign;
                //print(DEBUG);
                return false;
            }

        }
        //print(TEST);
        TEST = 0;

        //print(DEBUG);
        return true;


        //var increment = amount > 0 ? 0.01f : -0.01f;
        //var progress = 0f;

        //while(Mathf.Abs(progress) < Mathf.Abs(amount))
        //{
        //    // progress 远远 小于 amount - increment
        //    // 步伐依然为 increment = 0.01
        //    if (Mathf.Abs(progress) < Mathf.Abs(amount) - Mathf.Abs(increment))
        //    {
                // NOTHING
        //    }
        //    else // 缩小步伐(最后一步了)
        //    {
        //        increment = amount - progress;
        //    }

        //    Y += increment;
        //    progress += increment;

        //    if (Colliding())
        //    {
        //        Y -= increment;
        //        return false;
        //    }
        //}

        //return true;

    }

    private void OnTriggerEnter2D(Collider2D collision)
    {
            print("ENTER: " + collision + " " + name + "  " + TEST);
        
    }

    private void OnTriggerExit2D(Collider2D collision)
    {
            print("EXIT: " + collision + " " + name + "  " + TEST);
    }