private Transform player;
    private Vector3 offset;
    private float smoothing = 3;

    // Use this for initialization
    void Start () {
        player = GameObject.FindGameObjectWithTag("Player").transform;
        offset = transform.position - player.position;
    }
    
    // Update is called once per frame
    void LateUpdate () {
        Vector3 targetPosition = player.position + player.TransformDirection(offset);//將座標差轉換為區域性座標。可以使相機跟隨著旋轉
        transform.position = Vector3.Lerp(transform.position, targetPosition, Time.deltaTime * smoothing);
        transform.LookAt(player.position);
    }