252 lines
9.6 KiB
Markdown
252 lines
9.6 KiB
Markdown
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```c++
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// Manually clamp scene texture UV as if using a clamp sampler.
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MaterialFloat2 ClampSceneTextureUV(MaterialFloat2 BufferUV, const uint SceneTextureId)
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{
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float4 MinMax = GetSceneTextureUVMinMax(SceneTextureId);
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return clamp(BufferUV, MinMax.xy, MinMax.zw);
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}
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```
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## 相关函数的HLSL代码
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```c++
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float GetPixelDepth(FMaterialVertexParameters Parameters)
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{
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FLATTEN
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if (View.ViewToClip[3][3] < 1.0f)
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{
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// Perspective
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return GetScreenPosition(Parameters).w;
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}
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else
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{
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// Ortho
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return ConvertFromDeviceZ(GetScreenPosition(Parameters).z);
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}
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}
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float GetPixelDepth(FMaterialPixelParameters Parameters)
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{
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FLATTEN
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if (View.ViewToClip[3][3] < 1.0f)
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{
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// Perspective
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return GetScreenPosition(Parameters).w;
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}
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else
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{
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// Ortho
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return ConvertFromDeviceZ(GetScreenPosition(Parameters).z);
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}
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}
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float2 GetSceneTextureUV(FMaterialVertexParameters Parameters)
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{
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return ScreenAlignedPosition(GetScreenPosition(Parameters));
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}
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float2 GetSceneTextureUV(FMaterialPixelParameters Parameters)
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{
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return SvPositionToBufferUV(Parameters.SvPosition);
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}
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float2 GetViewportUV(FMaterialVertexParameters Parameters)
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{
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#if POST_PROCESS_MATERIAL
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return Parameters.WorldPosition.xy;
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#else
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return BufferUVToViewportUV(GetSceneTextureUV(Parameters));
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#endif
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}
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float2 GetPixelPosition(FMaterialVertexParameters Parameters)
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{
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return GetViewportUV(Parameters) * View.ViewSizeAndInvSize.xy;
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}
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#if POST_PROCESS_MATERIAL
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float2 GetPixelPosition(FMaterialPixelParameters Parameters)
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{
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return Parameters.SvPosition.xy - float2(PostProcessOutput_ViewportMin);
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}
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float2 GetViewportUV(FMaterialPixelParameters Parameters)
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{
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return GetPixelPosition(Parameters) * PostProcessOutput_ViewportSizeInverse;
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}
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#else
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float2 GetPixelPosition(FMaterialPixelParameters Parameters)
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{
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return Parameters.SvPosition.xy - float2(View.ViewRectMin.xy);
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}
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float2 GetViewportUV(FMaterialPixelParameters Parameters)
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{
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return SvPositionToViewportUV(Parameters.SvPosition);
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}
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```
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## 本质上是调用了SceneTextureLookup
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float4 SceneTextureLookup(float2 UV, int SceneTextureIndex, bool bFiltered)
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{
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FScreenSpaceData ScreenSpaceData = GetScreenSpaceData(UV, false);
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switch(SceneTextureIndex)
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{
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// order needs to match to ESceneTextureId
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case PPI_SceneColor:
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return float4(CalcSceneColor(UV), 0);
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case PPI_SceneDepth:
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return ScreenSpaceData.GBuffer.Depth;
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case PPI_DiffuseColor:
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return float4(ScreenSpaceData.GBuffer.DiffuseColor, 0);
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case PPI_SpecularColor:
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return float4(ScreenSpaceData.GBuffer.SpecularColor, 0);
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case PPI_SubsurfaceColor:
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return IsSubsurfaceModel(ScreenSpaceData.GBuffer.ShadingModelID) ? float4( ExtractSubsurfaceColor(ScreenSpaceData.GBuffer), ScreenSpaceData.GBuffer.CustomData.a ) : ScreenSpaceData.GBuffer.CustomData;
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case PPI_BaseColor:
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return float4(ScreenSpaceData.GBuffer.BaseColor, 0);
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case PPI_Specular:
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return ScreenSpaceData.GBuffer.Specular;
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case PPI_Metallic:
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return ScreenSpaceData.GBuffer.Metallic;
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case PPI_WorldNormal:
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return float4(ScreenSpaceData.GBuffer.WorldNormal, 0);
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case PPI_SeparateTranslucency:
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return float4(1, 1, 1, 1); // todo
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case PPI_Opacity:
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return ScreenSpaceData.GBuffer.CustomData.a;
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case PPI_Roughness:
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return ScreenSpaceData.GBuffer.Roughness;
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case PPI_MaterialAO:
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return ScreenSpaceData.GBuffer.GBufferAO;
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case PPI_CustomDepth:
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return ScreenSpaceData.GBuffer.CustomDepth;
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case PPI_PostProcessInput0:
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return Texture2DSample(PostProcessInput_0_Texture, bFiltered ? PostProcessInput_BilinearSampler : PostProcessInput_0_SharedSampler, UV);
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case PPI_PostProcessInput1:
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return Texture2DSample(PostProcessInput_1_Texture, bFiltered ? PostProcessInput_BilinearSampler : PostProcessInput_1_SharedSampler, UV);
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case PPI_PostProcessInput2:
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return Texture2DSample(PostProcessInput_2_Texture, bFiltered ? PostProcessInput_BilinearSampler : PostProcessInput_2_SharedSampler, UV);
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case PPI_PostProcessInput3:
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return Texture2DSample(PostProcessInput_3_Texture, bFiltered ? PostProcessInput_BilinearSampler : PostProcessInput_3_SharedSampler, UV);
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case PPI_PostProcessInput4:
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return Texture2DSample(PostProcessInput_4_Texture, bFiltered ? PostProcessInput_BilinearSampler : PostProcessInput_4_SharedSampler, UV);
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case PPI_DecalMask:
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return 0; // material compiler will return an error
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case PPI_ShadingModelColor:
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return float4(GetShadingModelColor(ScreenSpaceData.GBuffer.ShadingModelID), 1);
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case PPI_ShadingModelID:
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return float4(ScreenSpaceData.GBuffer.ShadingModelID, 0, 0, 0);
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case PPI_AmbientOcclusion:
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return ScreenSpaceData.AmbientOcclusion;
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case PPI_CustomStencil:
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return ScreenSpaceData.GBuffer.CustomStencil;
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case PPI_StoredBaseColor:
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return float4(ScreenSpaceData.GBuffer.StoredBaseColor, 0);
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case PPI_StoredSpecular:
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return float4(ScreenSpaceData.GBuffer.StoredSpecular.rrr, 0);
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case PPI_WorldTangent:
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return float4(ScreenSpaceData.GBuffer.WorldTangent, 0);
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case PPI_Anisotropy:
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return ScreenSpaceData.GBuffer.Anisotropy;
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default:
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return float4(0, 0, 0, 0);
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}
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}
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##
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FScreenSpaceData GetScreenSpaceData(float2 UV, bool bGetNormalizedNormal = true)
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{
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FScreenSpaceData Out;
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Out.GBuffer = GetGBufferData(UV, bGetNormalizedNormal);
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float4 ScreenSpaceAO = Texture2DSampleLevel(SceneTexturesStruct.ScreenSpaceAOTexture, SceneTexturesStruct_ScreenSpaceAOTextureSampler, UV, 0);
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Out.AmbientOcclusion = ScreenSpaceAO.r;
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return Out;
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}
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## GetGBufferData使用的GBufferXTexture的传入位置
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比如AOUpsamplePS（c++中为FDistanceFieldAOUpsamplePS）就带有FSceneTextureUniformParameters, SceneTextures。都是由对应的渲染函数的TRDGUniformBufferRef<FSceneTextureUniformParameters> SceneTexturesUniformBuffer形参传入。
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```c#
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FGBufferData GetGBufferData(float2 UV, bool bGetNormalizedNormal = true)
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{
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float4 GBufferA = Texture2DSampleLevel(SceneTexturesStruct.GBufferATexture, SceneTexturesStruct_GBufferATextureSampler, UV, 0);
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float4 GBufferB = Texture2DSampleLevel(SceneTexturesStruct.GBufferBTexture, SceneTexturesStruct_GBufferBTextureSampler, UV, 0);
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float4 GBufferC = Texture2DSampleLevel(SceneTexturesStruct.GBufferCTexture, SceneTexturesStruct_GBufferCTextureSampler, UV, 0);
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float4 GBufferD = Texture2DSampleLevel(SceneTexturesStruct.GBufferDTexture, SceneTexturesStruct_GBufferDTextureSampler, UV, 0);
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float CustomNativeDepth = Texture2DSampleLevel(SceneTexturesStruct.CustomDepthTexture, SceneTexturesStruct_CustomDepthTextureSampler, UV, 0).r;
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int2 IntUV = (int2)trunc(UV * View.BufferSizeAndInvSize.xy);
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uint CustomStencil = SceneTexturesStruct.CustomStencilTexture.Load(int3(IntUV, 0)) STENCIL_COMPONENT_SWIZZLE;
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#if ALLOW_STATIC_LIGHTING
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float4 GBufferE = Texture2DSampleLevel(SceneTexturesStruct.GBufferETexture, SceneTexturesStruct_GBufferETextureSampler, UV, 0);
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#else
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float4 GBufferE = 1;
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#endif
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float4 GBufferF = Texture2DSampleLevel(SceneTexturesStruct.GBufferFTexture, SceneTexturesStruct_GBufferFTextureSampler, UV, 0);
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#if WRITES_VELOCITY_TO_GBUFFER
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float4 GBufferVelocity = Texture2DSampleLevel(SceneTexturesStruct.GBufferVelocityTexture, SceneTexturesStruct_GBufferVelocityTextureSampler, UV, 0);
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#else
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float4 GBufferVelocity = 0;
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#endif
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float SceneDepth = CalcSceneDepth(UV);
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//FGBufferData DecodeGBufferData()通过解码GBuffer之后返回FGBufferData 结构体
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return DecodeGBufferData(GBufferA, GBufferB, GBufferC, GBufferD, GBufferE, GBufferF, GBufferVelocity, CustomNativeDepth, CustomStencil, SceneDepth, bGetNormalizedNormal, CheckerFromSceneColorUV(UV));
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}
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```
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## GetGBufferDataFromSceneTextures中使用的GBufferXTexture的传入位置
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SingleLayerWaterCompositePS中使用了GetGBufferDataFromSceneTextures()来获取GBuffer，这个数据是在SingleLayerWaterRendering.cpp中传入的。传入的变量FSingleLayerWaterCommonShaderParameters->FSceneTextureParameters SceneTextures中带有GBufferABCEDF与Depth、Stencil、Velocity贴图。
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```c++
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Texture2D SceneDepthTexture;
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Texture2D<uint2> SceneStencilTexture;
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Texture2D GBufferATexture;
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Texture2D GBufferBTexture;
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Texture2D GBufferCTexture;
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Texture2D GBufferDTexture;
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Texture2D GBufferETexture;
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Texture2D GBufferVelocityTexture;
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Texture2D GBufferFTexture;
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Texture2D<uint> SceneLightingChannels;
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FGBufferData GetGBufferDataFromSceneTextures(float2 UV, bool bGetNormalizedNormal = true)
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{
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float4 GBufferA = GBufferATexture.SampleLevel(GBufferATextureSampler, UV, 0);
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float4 GBufferB = GBufferBTexture.SampleLevel(GBufferBTextureSampler, UV, 0);
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float4 GBufferC = GBufferCTexture.SampleLevel(GBufferCTextureSampler, UV, 0);
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float4 GBufferD = GBufferDTexture.SampleLevel(GBufferDTextureSampler, UV, 0);
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float4 GBufferE = GBufferETexture.SampleLevel(GBufferETextureSampler, UV, 0);
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float4 GBufferF = GBufferFTexture.SampleLevel(GBufferFTextureSampler, UV, 0);
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float4 GBufferVelocity = GBufferVelocityTexture.SampleLevel(GBufferVelocityTextureSampler, UV, 0);
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uint CustomStencil = 0;
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float CustomNativeDepth = 0;
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float DeviceZ = SampleDeviceZFromSceneTextures(UV);
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float SceneDepth = ConvertFromDeviceZ(DeviceZ);
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//FGBufferData DecodeGBufferData()通过解码GBuffer之后返回FGBufferData 结构体
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return DecodeGBufferData(GBufferA, GBufferB, GBufferC, GBufferD, GBufferE, GBufferF, GBufferVelocity, CustomNativeDepth, CustomStencil, SceneDepth, bGetNormalizedNormal, CheckerFromSceneColorUV(UV));
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}
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```
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