vault backup: 2024-03-18 16:08:45

03-UnrealEngine/卡通渲染相关资料/渲染功能/ShaderModel/GBuffer&Material&BasePass.md

@@ -339,7 +339,97 @@ bool FMaterialInstanceResource::GetParameterValue(EMaterialParameterType Type, c
 	}
 ```
 
-### 是否需要Toon
+
+### BasePass EncodeGBufferToMRT/DecodeGBufferDataDirect逻辑笔记
+主要逻辑位于FShaderCompileUtilities::WriteGBufferInfoAutogen():
+```c++
+void FShaderCompileUtilities::WriteGBufferInfoAutogen(EShaderPlatform TargetPlatform, ERHIFeatureLevel::Type FeatureLevel = ERHIFeatureLevel::SM5)
+{
+	FGBufferParams DefaultParams = FetchGBufferParamsPipeline(TargetPlatform, GBL_Default);
+	FScopeLock MapLock(&GCriticalSection);
+
+	// For now, the logic always calculates the new GBuffer, and if it's the first time, write it, otherwise check it hasn't changed. We are doing this for
+	// debugging, and in the near future it will only calculate the GBuffer on the first time only.
+	FGBufferInfo DefaultBufferInfo = FetchFullGBufferInfo(DefaultParams);
+	FString AutoGenDirectory = GetAutoGenDirectory(TargetPlatform);
+	FString AutogenHeaderFilename = AutoGenDirectory / TEXT("AutogenShaderHeaders.ush");
+	FString AutogenHeaderFilenameTemp = AutoGenDirectory / TEXT("AutogenShaderHeaders_temp.ush");
+
+	if (GLastGBufferIsValid[TargetPlatform])
+	{
+		const bool bSame = IsGBufferInfoEqual(GLastGBufferInfo[TargetPlatform], DefaultBufferInfo);//判断GBufferInfo是否相同，不同则触发断言
+		check(bSame);
+	}
+	else
+	{
+		GLastGBufferIsValid[TargetPlatform] = true;
+		// should cache this properly, and serialize it, but this is a temporary fix.
+		GLastGBufferInfo[TargetPlatform] = DefaultBufferInfo;
+
+		FString OutputFileData;
+		OutputFileData += TEXT("// Copyright Epic Games, Inc. All Rights Reserved.\n");
+		OutputFileData += TEXT("\n");
+		OutputFileData += TEXT("#pragma once\n");
+		OutputFileData += TEXT("\n");
+
+		OutputFileData += TEXT("#if FEATURE_LEVEL >= FEATURE_LEVEL_SM5\n");
+		OutputFileData += TEXT("float SampleDeviceZFromSceneTexturesTempCopy(float2 UV)\n");
+		OutputFileData += TEXT("{\n");
+		OutputFileData += TEXT("\treturn SceneDepthTexture.SampleLevel(SceneDepthTextureSampler, UV, 0).r;\n");
+		OutputFileData += TEXT("}\n");
+		OutputFileData += TEXT("#endif\n");
+		OutputFileData += TEXT("\n");
+
+		OutputFileData += TEXT("#ifndef GBUFFER_LAYOUT\n");
+		OutputFileData += TEXT("#define GBUFFER_LAYOUT 0\n");
+		OutputFileData += TEXT("#endif\n");
+		OutputFileData += TEXT("\n");
+
+		for (uint32 Layout = 0; Layout < GBL_Num; ++Layout)
+		{
+			FGBufferParams Params = FetchGBufferParamsPipeline(TargetPlatform, (EGBufferLayout)Layout);
+			FGBufferInfo BufferInfo = FetchFullGBufferInfo(Params);
+
+			OutputFileData.Appendf(TEXT("#if GBUFFER_LAYOUT == %u\n\n"), Layout);
+			OutputFileData += CreateGBufferEncodeFunction(BufferInfo);
+
+			OutputFileData += TEXT("\n");
+
+			OutputFileData += CreateGBufferDecodeFunctionDirect(BufferInfo);
+
+			OutputFileData += TEXT("\n");
+			//OutputFileData += TEXT("#if SHADING_PATH_DEFERRED\n");
+			OutputFileData += TEXT("#if FEATURE_LEVEL >= FEATURE_LEVEL_SM5\n");
+			OutputFileData += TEXT("\n");
+
+			OutputFileData += CreateGBufferDecodeFunctionVariation(BufferInfo, EGBufferDecodeType::CoordUV, FeatureLevel);
+			OutputFileData += TEXT("\n");
+
+			OutputFileData += CreateGBufferDecodeFunctionVariation(BufferInfo, EGBufferDecodeType::CoordUInt, FeatureLevel);
+
+			OutputFileData += TEXT("\n");
+
+			OutputFileData += CreateGBufferDecodeFunctionVariation(BufferInfo, EGBufferDecodeType::SceneTextures, FeatureLevel);
+			OutputFileData += TEXT("\n");
+
+			OutputFileData += CreateGBufferDecodeFunctionVariation(BufferInfo, EGBufferDecodeType::SceneTexturesLoad, FeatureLevel);
+			OutputFileData += TEXT("\n");
+
+			OutputFileData += TEXT("#endif\n");
+			OutputFileData += TEXT("\n");
+
+			OutputFileData += TEXT("#endif\n");
+			OutputFileData += TEXT("\n");
+		}
+	...
+}
+```
+写入内容与这2句获取的FGbufferInfo有关：`FGBufferParams Params = FetchGBufferParamsPipeline(TargetPlatform, (EGBufferLayout)Layout);`和`FGBufferInfo BufferInfo = FetchFullGBufferInfo(Params);`
+
+
+![[ShaderGenerationUtil_CreateGBufferEncodeFunction.png|1200]]
+
+## 是否需要Toon
 在材质中：
 ```c++
 FMaterialRelevance UMaterialInterface::GetRelevance_Internal(const UMaterial* Material, ERHIFeatureLevel::Type InFeatureLevel) const