unity urp 16 高斯模糊

c0d3n4m · 发表于 2022-7-10 22:02

一、原理

高斯模糊得核心方程就是高斯函数

由这个函数计算出来得值计算出高斯核

另外，二维高斯核的计算复杂度为NxNxWxH，二维高斯核可以分解成两个一维的核进行两边卷积操作，来降低计算复杂度，为2xNxWxH。

二、代码

2.1 二维高斯核直接计算
Shader &#34;Unlit/18_GaussianBlur&#34;
{
Properties
{
      [HideInInspector]_MainTex (&#34;Texture&#34;, 2D) = &#34;white&#34; {}
      _BlurSize(&#34;Blur Size&#34;, Float) = 1.0
}
SubShader
{
      Tags
      {
         &#34;RenderPipeline&#34;=&#34;UniversalRenderPipeline&#34;
      }
      Cull Off
      ZWrite Off
      ZTest Always

      HLSLINCLUDE
      #include &#34;Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl&#34;
      CBUFFER_START(UnityPerMaterial)
      float _BlurSize;
      float4 _MainTex_TexelSize;
      CBUFFER_END
      TEXTURE2D(_MainTex);
      SAMPLER(sampler_MainTex);
      struct Attributes
      {
         float4 positionOS: POSITION;
         float2 texcoord: TEXCOORD0;
      };
      struct Varyings
      {
         float4 positionCS:SV_POSITION;
         float2 uv:TEXCOORD0;
      };
      ENDHLSL

      Pass
      {
         HLSLPROGRAM
         #pragma vertex vert
         #pragma fragment frag

         Varyings vert(Attributes input)
         {
            Varyings output;
            output.positionCS = TransformObjectToHClip(input.positionOS);
            output.uv = input.texcoord;
            return output;
         }

         half4 frag (Varyings input) : SV_Target
         {
            half4 tex = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv);
            float2 uv = input.uv;
            half4 col = float4(0,0,0,0);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(-1,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.098 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(0,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.098 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(-1,0)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.162 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv);
            col += 0.098 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,0)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.022 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,0)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,1)*_MainTex_TexelSize.xy*_BlurSize);

            return col;
         }
         ENDHLSL
      }
}
}
2.2
三、结果

二维高斯核的结果，可以发现明度明显的降低

四、参考

小小：机器视觉学习（二）高斯卷积

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unity urp 16 高斯模糊

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