Unity3D Shader:镜子的效果

Shader部分代码：

Shader "Custom/FanShe" {
Properties{
_MainTex("Albedo",2D) = "white"{}
_MainTint("Diffuse Color",Color)=(1,1,1,1)
_Cubemap("Cubemap",CUBE) = ""{}
_ReflAmount("Reflection Amount",Range(0.1,1.0))=0.5
}
SubShader{
Tags{"RenderType"="Opaque"}
LOD 200


CGPROGRAM
#pragma surface surf Lambert
#pragma target 3.0
struct Input {
float2 uv_MainTex;
float3 worldRefl;
};
sampler2D _MainTex;
samplerCUBE _Cubemap;
fixed4 _MainTint;
half _ReflAmount;
void surf(Input IN, inout SurfaceOutput o)
{
fixed4 c = tex2D(_MainTex, IN.uv_MainTex)*_MainTint;
o.Albedo = c.rgb;
o.Emission = texCUBE(_Cubemap, IN.worldRefl)*_ReflAmount;
o.Alpha = c.a;
}
ENDCG
}

FallBack "Diffuse"

}

C#部分代码

using System.Collections;
using System.Collections.Generic;
using UnityEngine;


public class Shader_FanShe : MonoBehaviour {
    public  Cubemap cubeMap;
    public Camera cam;
    Material curmat;
// Use this for initialization
void Start () {
        InvokeRepeating("change", 1, 0.1f);
        curmat = gameObject.GetComponent<Renderer>().material;
        if (curmat == null)
        {
            Debug.Log("cw");
        }
        
}

// Update is called once per frame
void Update () {

}
    void change()
    {
        cam.transform.rotation = Quaternion.identity;
        cam.RenderToCubemap(cubeMap);
        curmat.SetTexture("_Cubemap",cubeMap);
    }

}