unreal 4.25 subsurface shader 流程

gistfile1.txt

- ShadowProjectionPixelShader.usf/Main (画阴影到 Common.ush/LightAttenuationTexture 中)
    - SSSTransmission = ManualPCF(ShadowPosition.xy, Settings); （输出到 FadedSSSShadow）
    - OutColor = EncodeLightAttenuation(half4(FadedShadow, FadedSSSShadow, FadedShadow, FadedSSSShadow)) （最终输出）

- BasePassPixelShader.usf/FPixelShaderInOut_MainPS (画基本物体的 pass)
    - 调用 MaterialTemplate.ush 提供的方法（材质蓝图会根据 MaterialTemplate.ush 填充对应的方法）
      GetMaterialBaseColor
      GetMaterialMetallic
      GetMaterialSpecular
      GetXXX...

    - ShadingModelsMaterial.ush/SetGBufferForShadingModel 输出到 DeferredShadingCommon.ush/FGBufferData 结构体中
    
- DeferredLightPixelShaders.usf/DeferredLightPixelMain
    - DeferredShadingCommon.ush/GetScreenSpaceData （获取 GBuffer）
        - GetGBufferData {
            float4 GBufferA = FramebufferFetchMRT(1);
            float4 GBufferB = FramebufferFetchMRT(2);
            float4 GBufferC = FramebufferFetchMRT(3);
            float4 GBufferD = FramebufferFetchMRT(4);

            return DecodeGBufferData(GBufferA, GBufferB, GBufferC, GBufferD, GBufferE, GBufferF, GBufferVelocity, CustomNativeDepth, CustomStencil, SceneDepth, bGetNormalizedNormal, CheckerFromSceneColorUV(UV));
        }
    - GetPerPixelLightAttenuation (获取阴影贴图)

    - GetDynamicLighting
        - GetShadowTerms （用阴影贴图获取的数据计算阴影）
        - ShadingModels.ush/IntegrateBxDF（根据 shading model 调用对应的 BXDF）
            - SubsurfaceBxDF

    - OutColor += (Radiance * Attenuation) * OpaqueVisibility;

r.CompileShadersForDevelopment=0;