平面移动以及 画面重复

using UnityEngine;using System.Collections;public class Plane : MonoBehaviour {    // Use this for initialization    void Start () {    }    // Update is called once per frame    void Update () {    //控制移动方向        transform.Translate(Vector3.back * Time.deltaTime * 3);        if (transform.position.z < -30)        {        //控制连图位置            transform.position = new Vector3(transform.position.x, transform.position.y, 30);        }    }}