一、创建一个Cube

二、新建个脚本挂在Cube上

using UnityEngine;
using System.Collections;

public class MeshTest : MonoBehaviour {

    public float speed = 100.0F;
    void Update()
    {
        Mesh mesh = GetComponent<MeshFilter>().mesh;
        Vector3[] normals = mesh.normals;
        Quaternion rotation = Quaternion.AngleAxis(Time.deltaTime * speed, Vector3.up);
        int i = 0;
        //每帧改变所有面的法线方向,从而改变每个面的光照反射程度。
        while (i < normals.Length)
        {
            normals[i] = rotation * normals[i];
            i++;
        }
        mesh.normals = normals;
    }
}