【Unity HDRP】Custom Pass 遮挡显示及描边效果

Shader "Renderers/NewRenderersCustomPass"
{
    Properties
    {
        _Color("Color", Color) = (1,1,1,1)
        _ColorMap("ColorMap", 2D) = "white" {}

        // Transparency
        _AlphaCutoff("Alpha Cutoff", Range(0.0, 1.0)) = 0.5
    }

    HLSLINCLUDE

    #pragma target 4.5
    #pragma only_renderers d3d11 ps4 xboxone vulkan metal switch

    // #pragma enable_d3d11_debug_symbols

    //enable GPU instancing support
    #pragma multi_compile_instancing

    ENDHLSL

    SubShader
    {
        Pass
        {
            Name "FirstPass"
            Tags { "LightMode" = "FirstPass" }

            Blend Off
            ZWrite Off
            ZTest LEqual

            Cull Back

            HLSLPROGRAM

            // Toggle the alpha test
            #define _ALPHATEST_ON

            // Toggle transparency
            // #define _SURFACE_TYPE_TRANSPARENT

            // Toggle fog on transparent
            #define _ENABLE_FOG_ON_TRANSPARENT
            
            // List all the attributes needed in your shader (will be passed to the vertex shader)
            // you can see the complete list of these attributes in VaryingMesh.hlsl
            #define ATTRIBUTES_NEED_TEXCOORD0
            #define ATTRIBUTES_NEED_NORMAL
            #define ATTRIBUTES_NEED_TANGENT

            // List all the varyings needed in your fragment shader
            #define VARYINGS_NEED_TEXCOORD0
            #define VARYINGS_NEED_TANGENT_TO_WORLD
            
            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/RenderPass/CustomPass/CustomPassRenderers.hlsl"

            TEXTURE2D(_ColorMap);
            float4 _ColorMap_ST;
            float4 _Color;

            // If you need to modify the vertex datas, you can uncomment this code
            // Note: all the transformations here are done in object space
            // #define HAVE_MESH_MODIFICATION
            // AttributesMesh ApplyMeshModification(AttributesMesh input, float3 timeParameters)
            // {
            //     input.positionOS += input.normalOS * 0.0001; // inflate a bit the mesh to avoid z-fight
            //     return input;
            // }

            // Put the code to render the objects in your custom pass in this function
            void GetSurfaceAndBuiltinData(FragInputs fragInputs, float3 viewDirection, inout PositionInputs posInput, out SurfaceData surfaceData, out BuiltinData builtinData)
            {
                float2 colorMapUv = TRANSFORM_TEX(fragInputs.texCoord0.xy, _ColorMap);
                float4 result = SAMPLE_TEXTURE2D(_ColorMap, s_trilinear_clamp_sampler, colorMapUv) * _Color;
                float opacity = result.a;
                float3 color = result.rgb;

#ifdef _ALPHATEST_ON
                DoAlphaTest(opacity, _AlphaCutoff);
#endif

                // Write back the data to the output structures
                ZERO_INITIALIZE(BuiltinData, builtinData); // No call to InitBuiltinData as we don't have any lighting
                builtinData.opacity = opacity;
                builtinData.emissiveColor = float3(0, 0, 0);
                surfaceData.color = color;
            }

            #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/ShaderPass/ShaderPassForwardUnlit.hlsl"

            #pragma vertex Vert
            #pragma fragment Frag

            ENDHLSL
        }
    }
}

void GetSurfaceAndBuiltinData(FragInputs fragInputs, float3 viewDirection, inout PositionInputs posInput, out SurfaceData surfaceData, out BuiltinData builtinData)
  {
      // Write back the data to the output structures
      ZERO_INITIALIZE(BuiltinData, builtinData); // No call to InitBuiltinData as we don't have any lighting
      builtinData.opacity = 1;
      builtinData.emissiveColor = float3(0, 0, 0);
      surfaceData.color = _Color;
  }

Shader "FullScreen/NewFullScreenCustomPass"
{
    HLSLINCLUDE

    #pragma vertex Vert

    #pragma target 4.5
    #pragma only_renderers d3d11 ps4 xboxone vulkan metal switch

    #include "Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/RenderPass/CustomPass/CustomPassCommon.hlsl"

    // The PositionInputs struct allow you to retrieve a lot of useful information for your fullScreenShader:
    // struct PositionInputs
    // {
    //     float3 positionWS;  // World space position (could be camera-relative)
    //     float2 positionNDC; // Normalized screen coordinates within the viewport    : [0, 1) (with the half-pixel offset)
    //     uint2  positionSS;  // Screen space pixel coordinates                       : [0, NumPixels)
    //     uint2  tileCoord;   // Screen tile coordinates                              : [0, NumTiles)
    //     float  deviceDepth; // Depth from the depth buffer                          : [0, 1] (typically reversed)
    //     float  linearDepth; // View space Z coordinate                              : [Near, Far]
    // };

    // To sample custom buffers, you have access to these functions:
    // But be careful, on most platforms you can't sample to the bound color buffer. It means that you
    // can't use the SampleCustomColor when the pass color buffer is set to custom (and same for camera the buffer).
    // float4 SampleCustomColor(float2 uv);
    // float4 LoadCustomColor(uint2 pixelCoords);
    // float LoadCustomDepth(uint2 pixelCoords);
    // float SampleCustomDepth(float2 uv);

    // There are also a lot of utility function you can use inside Common.hlsl and Color.hlsl,
    // you can check them out in the source code of the core SRP package.

    float4 FullScreenPass(Varyings varyings) : SV_Target
    {
        UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(varyings);
        float depth = LoadCameraDepth(varyings.positionCS.xy);
        PositionInputs posInput = GetPositionInput(varyings.positionCS.xy, _ScreenSize.zw, depth, UNITY_MATRIX_I_VP, UNITY_MATRIX_V);
        float3 viewDirection = GetWorldSpaceNormalizeViewDir(posInput.positionWS);
        float4 color = float4(0.0, 0.0, 0.0, 0.0);

        // Load the camera color buffer at the mip 0 if we're not at the before rendering injection point
        if (_CustomPassInjectionPoint != CUSTOMPASSINJECTIONPOINT_BEFORE_RENDERING)
            color = float4(CustomPassLoadCameraColor(varyings.positionCS.xy, 0), 1);

        // Add your custom pass code here

        // Fade value allow you to increase the strength of the effect while the camera gets closer to the custom pass volume
        float f = 1 - abs(_FadeValue * 2 - 1);
        return float4(color.rgb + f, color.a);
    }

    ENDHLSL

    SubShader
    {
        Pass
        {
            Name "Custom Pass 0"

            ZWrite Off
            ZTest Always
            Blend SrcAlpha OneMinusSrcAlpha
            Cull Off

            HLSLPROGRAM
                #pragma fragment FullScreenPass
            ENDHLSL
        }
    }
    Fallback Off
}

#define c45 0.707107
#define c225 0.9238795
#define s225 0.3826834

#define MAXSAMPLES 16
static float2 offsets[MAXSAMPLES] = {
    float2(1, 0),
    float2(-1, 0),
    float2(0, 1),
    float2(0, -1),
    
    float2(c45, c45),
    float2(c45, -c45),
    float2(-c45, c45),
    float2(-c45, -c45),
    
    float2(c225, s225),
    float2(c225, -s225),
    float2(-c225, s225),
    float2(-c225, -s225),
    float2(s225, c225),
    float2(s225, -c225),
    float2(-s225, c225),
    float2(-s225, -c225)
};

Properties
{
    _SamplePrecision ("Sampling Precision", Range(1, 3)) = 1
    _OutlineWidth ("Outline Width", Float) = 2
    _OuterColor ("Outer Color", Color) = (1, 1, 0, 1)
}

  float4 FullScreenPass(Varyings varyings): SV_Target
  {
      UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(varyings);
      float depth = LoadCameraDepth(varyings.positionCS.xy);
      PositionInputs posInput = GetPositionInput(varyings.positionCS.xy, _ScreenSize.zw, depth, UNITY_MATRIX_I_VP, UNITY_MATRIX_V);
      
      //CustomColorBuffer中本次处理的像素的颜色值
      float4 c = LoadCustomColor(posInput.positionSS);
      
      //调整采样次数以4, 8, 16幂次增长
      int sampleCount = min(2 * pow(2, _SamplePrecision), MAXSAMPLES) ;

//计算每像素之间的uv差
      float2 uvOffsetPerPixel = 1.0 / _ScreenSize .xy;

      float4 outline = 0;
      for (uint i = 0; i < sampleCount; ++ i)
      {
          //取sampleCount次采样中的最大值
          outline = max(SampleCustomColor(posInput.positionNDC + uvOffsetPerPixel * _OutlineWidth * offsets[i]), outline);
      }

//去掉原本纯色块的部分
      outline *= _OuterColor * (1 - c.a);

      return outline;
  }

Properties
{
    _SamplePrecision ("Sampling Precision", Range(1, 3)) = 1
    _OutlineWidth ("Outline Width", Float) = 1
    _OuterColor ("Outer Color", Color) = (1, 1, 0, 1)

    _InnerColor ("Inner Color", Color) = (1, 1, 0, 1)
    _Texture ("Texture", 2D) = "black" { }
    _TextureSize ("Texture Pixels Size", float) = 32
}

      ......
      //非描边的内容用斜线填充了，则不再需要这步操作了
//outline *= _OuterColor * (1 - c.a);

      //读取CustomDepthBuffer
      float d = LoadCustomDepth(posInput.positionSS);

      //进行深度的判断，如果判定为被遮挡则用我们设置的透明度，反之则为0。
      //0.000001为bias，避免浮点数的精度问题导致的误差。
      float alphaFactor = (depth > d + 0.000001) ?_BehindFactor: 0;
      //对InnerColorTexture进行采样
      float4 innerColor = SAMPLE_TEXTURE2D(_Texture, s_trilinear_repeat_sampler, posInput.positionSS / _TextureSize) * _InnerColor;
      
      innerColor.a *= alphaFactor;

      float4 output = 0;
//将描边赋值给output
      output = lerp(output, _OuterColor * float4(outline.rgb, 1), outline.a);
      //将纯色色块覆盖的区域以InnerColor替代
      output = lerp(output, innerColor * float4(c.rgb, 1), c.a);
      
      return output;