Unity 攝像機平滑跟隨

using UnityEngine;
public class CameraLag : MonoBehaviour
{
    public Transform    attach;
    public Transform target;
    public float time = 1.0f;

    public Vector3 pos;
    Vector3 spd = Vector3.zero;

    void Start()
    {
        if ( attach )
            pos = attach.position;
    }

    void LateUpdate()
    {
        if ( attach )
        {
            Vector3 cpos = attach.position;

            pos = Vector3.SmoothDamp(pos, cpos, ref spd, time);
            transform.position = pos;

            if ( target )
            {
                transform.rotation = Quaternion.LookRotation(target.position - pos);
            }
        }
    }
}