Unity shader学习之屏幕后期处理效果之均值模糊

均值模糊，也使用卷积来实现，之不过卷积中每个值均相等，且相加等于1。

代码如下，

子类：

using UnityEngine;

public class MeanBlurRenderer : PostEffectRenderer
{
    protected override string ShaderName
    {
        get { return "Custom/Mean Blur"; }
    }
}

shader

Shader "Custom/Mean Blur"
{
    Properties
    {
        _MainTex("Main Texture", 2D) = "white" {}
    }

    SubShader
    {
        Pass
        {
            Cull Off
            ZWrite Off
            ZTest Always

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            sampler2D _MainTex;
            float4 _MainTex_TexelSize;

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

            struct v2f
            {
                float4 pos : SV_POSITION;
                float2 uv[9] : TEXCOORD0;
            };

            v2f vert(appdata v)
            {
                v2f o;
                o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                o.uv[0] = v.uv + _MainTex_TexelSize.xy * float2(-1, 1);
                o.uv[1] = v.uv + _MainTex_TexelSize.xy * float2(0, 1);
                o.uv[2] = v.uv + _MainTex_TexelSize.xy * float2(1, 1);
                o.uv[3] = v.uv + _MainTex_TexelSize.xy * float2(-1, 0);
                o.uv[4] = v.uv + _MainTex_TexelSize.xy * float2(0, 0);
                o.uv[5] = v.uv + _MainTex_TexelSize.xy * float2(1, 0);
                o.uv[6] = v.uv + _MainTex_TexelSize.xy * float2(-1, -1);
                o.uv[7] = v.uv + _MainTex_TexelSize.xy * float2(0, -1);
                o.uv[8] = v.uv + _MainTex_TexelSize.xy * float2(1, -1);
                return o;
            }

            fixed4 frag(v2f i) : SV_TARGET
            {
                float4 col = float4(0, 0, 0, 0);
                for(int k = 0; k < 9; k++)
                {
                    float4 tex = tex2D(_MainTex, i.uv[k]);
                    col += tex;
                }
                return col * 0.1111;
            }

            ENDCG
        }
    }

    Fallback Off
}

效果，左边为正常，右边为均值模糊：