void LateUpdate() //對攝像機的操作寫在LateUpdate裡
  {
           x += Input.GetAxis("Mouse X") * rotateSpeed * Time.deltaTime;
           y -= Input.GetAxis("Mouse Y") * rotateSpeed * Time.deltaTime;
            //根據人物位置確定攝像機的位置，這裡用四元數進行了旋轉
            Quaternion camPosRotation = Quaternion.Euler(y, x, 0);
            mTrans.position
 
 = camPosRotation * distanceVec + player.position;
            mTrans.LookAt(player.position);
  }