Unity Shader实现模糊效果

float4 frag(v2f o):SV_TARGET{
 fixed4 color = tex2D(_MainTex,o.uv);//,float2(_Scale,_Scale),float2(_Scale,_Scale)
 
 float2 uv1= o.uv +float2(_Scale,_Scale);
 fixed4 color2 = tex2D(_MainTex,uv1);

 float2 uv2= o.uv -float2(_Scale,_Scale);
 fixed4 color3 = tex2D(_MainTex,uv2);

 return (color+color2+color3)/3;
}

Shader "Custom/TestShader40" {
 Properties{
  _MainTex("MainTex",2D)="White"{}
  _Scale("Scale",Range(0,0.1))=0
 }
 SubShader{
  Tags { "RenderType"="Opaque" }
  Pass{
   CGPROGRAM
    #pragma vertex vert
    #pragma fragment frag
    #pragma target 3.0
    #include "Lighting.cginc"

    sampler2D  _MainTex;
    float4 _MainTex_ST;
    float _Scale;

    struct a2v{
     float4 pos:POSITION;
     float4 uv:TEXCOORD0;
    };

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

    v2f vert(a2v v){
     v2f o;
     o.wPos = UnityObjectToClipPos(v.pos);
     o.uv=TRANSFORM_TEX(v.uv,_MainTex);

     return o;
    }

    float4 frag(v2f o):SV_TARGET{
     fixed4 color = tex2D(_MainTex,o.uv,float2(_Scale,_Scale),float2(_Scale,_Scale));

     return color;
    }
   ENDCG
  }
 }
}