【自定义Post Processing Volume】径向模糊(Radial Blur)

之前是把径向模糊应用与粒子系统中，这次把效果整合进Post Processing Volume，也是做成Renderer Feature的形式，通过Volume Component控制参数，自定义Volume的代码与之前LetterBoxing的写法基本一致，只需把Shader和Volume参数的定义修改一下。

Shader

Shader "MyAct/RadialBlur"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" }
        
        Cull Off 
        ZWrite Off
        ZTest Always
        
        Pass
        {
            CGPROGRAM
            #pragma vertex Vert
            #pragma fragment Frag

            #include "UnityCG.cginc"

            sampler2D _MainTex;
            half4 _Param;

            #define _Offset _Param.x
            #define _Iteration _Param.y
            #define _Center _Param.zw
            
            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

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

            v2f Vert(appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 Frag (v2f i) : SV_Target
            {
                float2 blurVector = (_Center - i.uv.xy) * _Offset;
		
		half4 accumulateColor = half4(0, 0, 0, 0);
		
		[unroll(30)]//让编译器展开循环，执行效率更佳
		for (int j = 0; j < _Iteration; j ++)
		{
		    accumulateColor += tex2D(_MainTex, i.uv);
		    i.uv.xy += blurVector;
		}
		
		return accumulateColor / _Iteration;
            }
            ENDCG
        }
    }
}

参考资料

• 十种图像模糊算法的总结与实现

post processing shader unity