//Shader

Shader "Hidden/GaussianBlur"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _BlurSize ("Blur Size", Float) = 0.1
    }

    CGINCLUDE

    #include "UnityCG.cginc"

    sampler2D _MainTex;  
    uniform half4 _MainTex_TexelSize;  
    uniform float _BlurSize;  

    
 
static const half weight[4] = {0.0205, 0.0855, 0.232, 0.324};
    static const half4 coordOffset = half4(1.0h,1.0h,-1.0h,-1.0h);

    struct v2f_blurSGX
    {
        float4 pos:SV_POSITION;
        half2 uv:TEXCOORD0;
        half4 uvoff[3]:TEXCOORD1;
    };

    v2f_blurSGX vert_BlurHorizontal(appdata_img v)
    {
        v2f_blurSGX o;
        o.pos 
 
= mul(UNITY_MATRIX_MVP,v.vertex);
        o.uv = v.texcoord.xy;
        half2 offs = _MainTex_TexelSize.xy*half2(1,0)*_BlurSize;
        o.uvoff[0] = v.texcoord.xyxy+offs.xyxy*coordOffset*3;
        o.uvoff[1] = v.texcoord.xyxy+offs.xyxy*coordOffset*2;
        o.uvoff[2] = v.texcoord.xyxy+offs.xyxy*coordOffset;

        
 
return o;
    }

    v2f_blurSGX vert_BlurVertical(appdata_img v)
    {
        v2f_blurSGX o;
        o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
        o.uv = v.texcoord.xy;

        half2 offs = _MainTex_TexelSize.xy*half2(0,1)*_BlurSize;
        o.uvoff[0] = v.texcoord.xyxy+offs.xyxy*coordOffset*3;
        o.uvoff[1] = v.texcoord.xyxy+offs.xyxy*coordOffset*2;
        o.uvoff[2] = v.texcoord.xyxy+offs.xyxy*coordOffset;

        return o;
    }

    fixed4 frag_Blur(v2f_blurSGX i):SV_Target
    {
        
        fixed4 c = tex2D(_MainTex,i.uv)*weight[3];
        for(int idx=0; idx<3; idx++)
        {
            c+=tex2D(_MainTex,i.uvoff[idx].xy)*weight[idx];
            c+=tex2D(_MainTex,i.uvoff[idx].zw)*weight[idx];
        }

        return c;
    }

    ENDCG

    SubShader
    {
        // No culling or depth
        Cull Off ZWrite Off 

        Pass
        {
            ZTest Always
            CGPROGRAM
            #pragma vertex vert_BlurHorizontal
            #pragma fragment frag_Blur
            

            ENDCG
        }

        Pass
        {
            ZTest Always
            CGPROGRAM
            #pragma vertex vert_BlurVertical
            #pragma fragment frag_Blur
            

            ENDCG
        }
    }
}

//c#

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(Camera))]
[ExecuteInEditMode]
public class Blur : MonoBehaviour {

    public Material ma;

    public float BlurSize =10;
    public int interator = 2;



    void OnRenderImage (RenderTexture sourceTexture, RenderTexture destTexture)
    {    

        ma.SetFloat ("_BlurSize", BlurSize);
        int rtW = sourceTexture.width/8;
        int rtH = sourceTexture.height/8;


        RenderTexture rtTempA = RenderTexture.GetTemporary (rtW, rtH, 0, sourceTexture.format);
        rtTempA.filterMode = FilterMode.Bilinear;

        RenderTexture rtTempB = RenderTexture.GetTemporary (rtW, rtH, 0, sourceTexture.format);
        rtTempB.filterMode = FilterMode.Bilinear;


        for (int i = 0; i < interator; i++) {
            if (0 == i) {
                Graphics.Blit (sourceTexture, rtTempA,ma,0);
                Graphics.Blit (rtTempA, rtTempB, ma, 1);
            } else {
                    
                Graphics.Blit (rtTempB, rtTempA, ma, 0);
                Graphics.Blit (rtTempA, rtTempB,ma,1);
            }

        }


  

        Graphics.Blit(rtTempB, destTexture);

        RenderTexture.ReleaseTemporary(rtTempA);
        RenderTexture.ReleaseTemporary(rtTempB);
    }





}

Unity3D Shader 高斯模糊