1、新建一个3d工程
2、生成一个cube

3、生成一个脚本(名字要为move!!!)(右键生成选项)
代码
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class move : MonoBehaviour
{
private Transform son;
public bool moveToLeft = true;
private float speed = 2;
private void Start()
{
son = this.transform;
}
private void Update()
{
Move();
}
private void Move()
{
if (son.position.x <= -3 && moveToLeft)
{
moveToLeft = false;
}
else if (son.position.x >= 3 && !moveToLeft)
moveToLeft = true;
son.position += (moveToLeft ? Vector3.left : Vector3.right) * Time.deltaTime * speed;
}
}

4、将物体的相关脚本拖到层级视图新建的cube中

5、点击运行,就可以看到结果了!