[UnityShader3]模糊效果

场景布置：

1.创建两个Image，给底层的Image赋值图片，并让它覆盖整个屏幕；不用给上层的Image赋值图片，让它覆盖整个屏幕。

2.将下面的shader赋给上层的Image。

Shader "hongGe/GrabTexture3" 
{
    Properties 
    {
		_Offset ("UVOffset", float) = 0.01//uv偏移
		_Percent ("Percent", float) = 0.1//百分比
    }
    SubShader 
    {
		Tags{"Queue"="Transparent"}
		GrabPass{}
		       
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"
			sampler2D _GrabTexture;
			float _Offset;
			float _Percent;

            struct VertexOutput 
            {
                float4 pos:SV_POSITION;
                float2 uv:TEXCOORD0;
            };

            VertexOutput vert(appdata_base v)
            {
                VertexOutput o;
                o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
                o.uv = float2(v.texcoord.x , 1-v.texcoord.y);

                return o;
            }

            float4 frag(VertexOutput input):COLOR
            {
				half4 a = tex2D(_GrabTexture,input.uv + float2(_Offset,0));
				half4 b = tex2D(_GrabTexture,input.uv + float2(-_Offset,0));
				half4 c = tex2D(_GrabTexture,input.uv + float2(0,_Offset));
				half4 d = tex2D(_GrabTexture,input.uv + float2(0,-_Offset));

				half4 e = tex2D(_GrabTexture,input.uv + float2(_Offset / 2,_Offset / 2));
				half4 f = tex2D(_GrabTexture,input.uv + float2(-_Offset / 2,_Offset / 2));
				half4 g = tex2D(_GrabTexture,input.uv + float2(_Offset / 2,-_Offset / 2));
				half4 h = tex2D(_GrabTexture,input.uv + float2(-_Offset / 2,-_Offset / 2));
				
				half4 texCol = tex2D(_GrabTexture,input.uv);
				texCol = (texCol + a + b + c + d + e + f + g + h) * _Percent;
                return texCol;				
            }
            ENDCG
        }        
    } 
    FallBack "Diffuse"
}

对比图：