使一个片同时支持正反面图片显示

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Custom/TwoFaceShader"
{
    Properties
    {
        _MainTex_1 ("贴图1", 2D) = "white" {}
        _MainTex_2 ("贴图2",2D) = ""{} 
    }
    SubShader
    {
        
        Pass {
            Tags{"LightMode" = "ForwardBase"}
            LOD 100
            
            //在这个通道内剔除背面渲染
            Cull Back
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
            
            struct appdata {
                float4 vertex:POSITION;
                float2 uv:TEXCOORD0;
            };

            struct v2f{
                float4 vertex:SV_POSITION;
                float2 uv:TEXCOORD0;
            };
            sampler2D _MainTex_1;
            //使用TRANSFORM_TEX时需要定义一个 _贴图的变量名_ST 用来供给系统使用
            float4 _MainTex_1_ST;
            
            v2f vert(appdata v){
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv,_MainTex_1);
                return o;
            }

            fixed4 frag(v2f v):SV_TARGET{
                fixed4 col= tex2D(_MainTex_1,v.uv);
                return col;
            }

             ENDCG    
        }

        Pass{
            Tags{"LightMode" = "ForwardBase"}
            Cull Front 

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag 
            #include "UnityCG.cginc"

            struct appdata{
                float4 vertex:POSITION;
                float2 uv:TEXCOORD0;
            };

            struct v2f{
                float4 vertex:SV_POSITION;
                float2 uv:TEXCOORD0;
            };

            sampler2D _MainTex_2;
            float4 _MainTex_2_ST;

            v2f vert(appdata v){
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv,_MainTex_2);
                return o;
            }

            fixed4 frag(v2f v):SV_TARGET
            {
                fixed4 col = tex2D(_MainTex_2,v.uv);
                return col;
            }

            ENDCG
        }
    }
    FallBack "Diffuse"
}