unity边缘检测Shader

Shader "Custom/Edge" {  
    Properties {  
        _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}//主相机的纹理  
    }  
  
  
    SubShader {  
    Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}  
    LOD 100  
      
    Cull Off  
    Blend Off  
    Pass {    
        CGPROGRAM  
            #pragma vertex vert  
            #pragma fragment frag  
              
            #include "UnityCG.cginc"  
  
            struct appdata_t {  
                float4 vertex : POSITION;  
                float2 texcoord : TEXCOORD0;  
            };  
  
            struct v2f {  
                float4 vertex : SV_POSITION;  
                half2 texcoord : TEXCOORD0;  
            };  
  
            sampler2D _MainTex;