UE4阴影初始化【2】

void FProjectedShadowInfo::GatherDynamicMeshElements(FSceneRenderer& Renderer, FVisibleLightInfo& VisibleLightInfo, TArray<const FSceneView*>& ReusedViewsArray,
	FGlobalDynamicIndexBuffer& DynamicIndexBuffer, FGlobalDynamicVertexBuffer& DynamicVertexBuffer, FGlobalDynamicReadBuffer& DynamicReadBuffer)
{
	QUICK_SCOPE_CYCLE_COUNTER(STAT_Shadow_GatherDynamicMeshElements);

	check(ShadowDepthView && IsInRenderingThread());

	if (DynamicSubjectPrimitives.Num() > 0 || ReceiverPrimitives.Num() > 0 || SubjectTranslucentPrimitives.Num() > 0)
	{
		// Backup properties of the view that we will override
		FMatrix OriginalViewMatrix = ShadowDepthView->ViewMatrices.GetViewMatrix();

		// Override the view matrix so that billboarding primitives will be aligned to the light
		ShadowDepthView->ViewMatrices.HackOverrideViewMatrixForShadows(ShadowViewMatrix);

		ReusedViewsArray[0] = ShadowDepthView;

		if (bPreShadow && GPreshadowsForceLowestLOD)
		{
			ShadowDepthView->DrawDynamicFlags = EDrawDynamicFlags::ForceLowestLOD;
		}

		if (CascadeSettings.bFarShadowCascade)
		{
			(int32&)ShadowDepthView->DrawDynamicFlags |= (int32)EDrawDynamicFlags::FarShadowCascade;
		}

		if (IsWholeSceneDirectionalShadow())
		{
			ShadowDepthView->SetPreShadowTranslation(FVector(0, 0, 0));
			ShadowDepthView->SetDynamicMeshElementsShadowCullFrustum(&CascadeSettings.ShadowBoundsAccurate);
			GatherDynamicMeshElementsArray(ShadowDepthView, Renderer, DynamicIndexBuffer, DynamicVertexBuffer, DynamicReadBuffer, 
				DynamicSubjectPrimitives, ReusedViewsArray, DynamicSubjectMeshElements, NumDynamicSubjectMeshElements);
			ShadowDepthView->SetPreShadowTranslation(PreShadowTranslation);
		}
		else
		{
			ShadowDepthView->SetPreShadowTranslation(PreShadowTranslation);
			ShadowDepthView->SetDynamicMeshElementsShadowCullFrustum(&CasterFrustum);
			GatherDynamicMeshElementsArray(ShadowDepthView, Renderer, DynamicIndexBuffer, DynamicVertexBuffer, DynamicReadBuffer, 
				DynamicSubjectPrimitives, ReusedViewsArray, DynamicSubjectMeshElements, NumDynamicSubjectMeshElements);
		}

		ShadowDepthView->DrawDynamicFlags = EDrawDynamicFlags::None;

		int32 NumDynamicSubjectTranslucentMeshElements = 0;
		ShadowDepthView->SetDynamicMeshElementsShadowCullFrustum(&CasterFrustum);
		GatherDynamicMeshElementsArray(ShadowDepthView, Renderer, DynamicIndexBuffer, DynamicVertexBuffer, DynamicReadBuffer, 
			SubjectTranslucentPrimitives, ReusedViewsArray, DynamicSubjectTranslucentMeshElements, NumDynamicSubjectTranslucentMeshElements);

		Renderer.MeshCollector.ProcessTasks();
    }

	
	// Create a pass uniform buffer so we can build mesh commands now in InitDynamicShadows.  This will be updated with the correct contents just before the actual pass.
	const EShadingPath ShadingPath = FSceneInterface::GetShadingPath(Renderer.FeatureLevel);
	FRHIUniformBuffer* PassUniformBuffer = nullptr;
	if (ShadingPath == EShadingPath::Deferred)
	{
		FShadowDepthPassUniformParameters ShadowDepthParameters;
		ShadowDepthPassUniformBuffer = TUniformBufferRef<FShadowDepthPassUniformParameters>::CreateUniformBufferImmediate(ShadowDepthParameters, UniformBuffer_MultiFrame, EUniformBufferValidation::None);
		PassUniformBuffer = ShadowDepthPassUniformBuffer;
	}
	else if (ShadingPath == EShadingPath::Mobile)
	{
		FMobileShadowDepthPassUniformParameters ShadowDepthParameters;
		MobileShadowDepthPassUniformBuffer = TUniformBufferRef<FMobileShadowDepthPassUniformParameters>::CreateUniformBufferImmediate(ShadowDepthParameters, UniformBuffer_MultiFrame, EUniformBufferValidation::None);
		PassUniformBuffer = MobileShadowDepthPassUniformBuffer;
	}

	SetupMeshDrawCommandsForShadowDepth(Renderer, PassUniformBuffer);
	SetupMeshDrawCommandsForProjectionStenciling(Renderer);
}

ShadowSetup.cpp 

void FProjectedShadowInfo::SetupMeshDrawCommandsForShadowDepth(FSceneRenderer& Renderer, FRHIUniformBuffer* PassUniformBuffer)
{
	QUICK_SCOPE_CYCLE_COUNTER(STAT_SetupMeshDrawCommandsForShadowDepth);

	FShadowDepthPassMeshProcessor* MeshPassProcessor = new(FMemStack::Get()) FShadowDepthPassMeshProcessor(
		Renderer.Scene,
		ShadowDepthView,
		ShadowDepthView->ViewUniformBuffer,
		PassUniformBuffer,
		GetShadowDepthType(),
		nullptr);

	if (Renderer.ShouldDumpMeshDrawCommandInstancingStats())
	{
		FString PassNameForStats;
		GetShadowTypeNameForDrawEvent(PassNameForStats);
		ShadowDepthPass.SetDumpInstancingStats(TEXT("ShadowDepth ") + PassNameForStats);
	}
	
	const uint32 InstanceFactor = !GetShadowDepthType().bOnePassPointLightShadow || RHISupportsGeometryShaders(Renderer.Scene->GetShaderPlatform()) ? 1 : 6;

	ShadowDepthPass.DispatchPassSetup(
		Renderer.Scene,
		*ShadowDepthView,
		EMeshPass::Num,
		FExclusiveDepthStencil::DepthNop_StencilNop,
		MeshPassProcessor,
		DynamicSubjectMeshElements,
		nullptr,
		NumDynamicSubjectMeshElements * InstanceFactor,
		SubjectMeshCommandBuildRequests,
		NumSubjectMeshCommandBuildRequestElements * InstanceFactor,
		ShadowDepthPassVisibleCommands);

	Renderer.DispatchedShadowDepthPasses.Add(&ShadowDepthPass);
}

void FParallelMeshDrawCommandPass::DispatchPassSetup(
	FScene* Scene,
	const FViewInfo& View,
	EMeshPass::Type PassType,
	FExclusiveDepthStencil::Type BasePassDepthStencilAccess,
	FMeshPassProcessor* MeshPassProcessor,
	const TArray<FMeshBatchAndRelevance, SceneRenderingAllocator>& DynamicMeshElements,
	const TArray<FMeshPassMask, SceneRenderingAllocator>* DynamicMeshElementsPassRelevance,
	int32 NumDynamicMeshElements,
	TArray<const FStaticMeshBatch*, SceneRenderingAllocator>& InOutDynamicMeshCommandBuildRequests,
	int32 NumDynamicMeshCommandBuildRequestElements,
	FMeshCommandOneFrameArray& InOutMeshDrawCommands,
	FMeshPassProcessor* MobileBasePassCSMMeshPassProcessor,
	FMeshCommandOneFrameArray* InOutMobileBasePassCSMMeshDrawCommands
)
{
	TRACE_CPUPROFILER_EVENT_SCOPE(ParallelMdcDispatchPassSetup);
	check(!TaskEventRef.IsValid() && MeshPassProcessor != nullptr && TaskContext.PrimitiveIdBufferData == nullptr);
	check((PassType == EMeshPass::Num) == (DynamicMeshElementsPassRelevance == nullptr));

	MaxNumDraws = InOutMeshDrawCommands.Num() + NumDynamicMeshElements + NumDynamicMeshCommandBuildRequestElements;

	TaskContext.MeshPassProcessor = MeshPassProcessor;
	TaskContext.MobileBasePassCSMMeshPassProcessor = MobileBasePassCSMMeshPassProcessor;
	TaskContext.DynamicMeshElements = &DynamicMeshElements;
	TaskContext.DynamicMeshElementsPassRelevance = DynamicMeshElementsPassRelevance;

	TaskContext.View = &View;
	TaskContext.ShadingPath = Scene->GetShadingPath();
	TaskContext.ShaderPlatform = Scene->GetShaderPlatform();
	TaskContext.PassType = PassType;
	TaskContext.bUseGPUScene = UseGPUScene(GMaxRHIShaderPlatform, View.GetFeatureLevel());
	TaskContext.bDynamicInstancing = IsDynamicInstancingEnabled(View.GetFeatureLevel());
	TaskContext.bReverseCulling = View.bReverseCulling;
	TaskContext.bRenderSceneTwoSided = View.bRenderSceneTwoSided;
	TaskContext.BasePassDepthStencilAccess = BasePassDepthStencilAccess;
	TaskContext.DefaultBasePassDepthStencilAccess = Scene->DefaultBasePassDepthStencilAccess;
	TaskContext.NumDynamicMeshElements = NumDynamicMeshElements;
	TaskContext.NumDynamicMeshCommandBuildRequestElements = NumDynamicMeshCommandBuildRequestElements;

	// Only apply instancing for ISR to main view passes
	const bool bIsMainViewPass = PassType != EMeshPass::Num && (FPassProcessorManager::GetPassFlags(TaskContext.ShadingPath, TaskContext.PassType) & EMeshPassFlags::MainView) != EMeshPassFlags::None;
	TaskContext.InstanceFactor = (bIsMainViewPass && View.IsInstancedStereoPass()) ? 2 : 1;

	// Setup translucency sort key update pass based on view.
	TaskContext.TranslucencyPass = ETranslucencyPass::TPT_MAX;
	TaskContext.TranslucentSortPolicy = View.TranslucentSortPolicy;
	TaskContext.TranslucentSortAxis = View.TranslucentSortAxis;
	TaskContext.ViewOrigin = View.ViewMatrices.GetViewOrigin();
	TaskContext.ViewMatrix = View.ViewMatrices.GetViewMatrix();
	TaskContext.PrimitiveBounds = &Scene->PrimitiveBounds;

	switch (PassType)
	{
		case EMeshPass::TranslucencyStandard: TaskContext.TranslucencyPass = ETranslucencyPass::TPT_StandardTranslucency; break;
		case EMeshPass::TranslucencyAfterDOF: TaskContext.TranslucencyPass = ETranslucencyPass::TPT_TranslucencyAfterDOF; break;
		case EMeshPass::TranslucencyAfterDOFModulate: TaskContext.TranslucencyPass = ETranslucencyPass::TPT_TranslucencyAfterDOFModulate; break;
		case EMeshPass::TranslucencyAll: TaskContext.TranslucencyPass = ETranslucencyPass::TPT_AllTranslucency; break;
		case EMeshPass::MobileInverseOpacity: TaskContext.TranslucencyPass = ETranslucencyPass::TPT_StandardTranslucency; break;
	}

	FMemory::Memswap(&TaskContext.MeshDrawCommands, &InOutMeshDrawCommands, sizeof(InOutMeshDrawCommands));
	FMemory::Memswap(&TaskContext.DynamicMeshCommandBuildRequests, &InOutDynamicMeshCommandBuildRequests, sizeof(InOutDynamicMeshCommandBuildRequests));

	if (TaskContext.ShadingPath == EShadingPath::Mobile && TaskContext.PassType == EMeshPass::BasePass)
	{
		FMemory::Memswap(&TaskContext.MobileBasePassCSMMeshDrawCommands, InOutMobileBasePassCSMMeshDrawCommands, sizeof(*InOutMobileBasePassCSMMeshDrawCommands));
	}
	else
	{
		check(MobileBasePassCSMMeshPassProcessor == nullptr && InOutMobileBasePassCSMMeshDrawCommands == nullptr);
	}

	if (MaxNumDraws > 0)
	{
		// Preallocate resources on rendering thread based on MaxNumDraws.
		bPrimitiveIdBufferDataOwnedByRHIThread = false;
		TaskContext.PrimitiveIdBufferDataSize = TaskContext.InstanceFactor * MaxNumDraws * sizeof(int32);
		TaskContext.PrimitiveIdBufferData = FMemory::Malloc(TaskContext.PrimitiveIdBufferDataSize);
		PrimitiveIdVertexBufferPoolEntry = GPrimitiveIdVertexBufferPool.Allocate(TaskContext.PrimitiveIdBufferDataSize);
		TaskContext.MeshDrawCommands.Reserve(MaxNumDraws);
		TaskContext.TempVisibleMeshDrawCommands.Reserve(MaxNumDraws);

		const bool bExecuteInParallel = FApp::ShouldUseThreadingForPerformance()
			&& CVarMeshDrawCommandsParallelPassSetup.GetValueOnRenderThread() > 0
			&& GIsThreadedRendering; // Rendering thread is required to safely use rendering resources in parallel.

		if (bExecuteInParallel)
		{
			if (GAllowOnDemandShaderCreation && RHISupportsMultithreadedShaderCreation(GMaxRHIShaderPlatform))
			{
				TaskEventRef = TGraphTask<FMeshDrawCommandPassSetupTask>::CreateTask(nullptr, ENamedThreads::GetRenderThread()).ConstructAndDispatchWhenReady(TaskContext);
			}
			else
			{
				FGraphEventArray DependentGraphEvents;
				DependentGraphEvents.Add(TGraphTask<FMeshDrawCommandPassSetupTask>::CreateTask(nullptr, ENamedThreads::GetRenderThread()).ConstructAndDispatchWhenReady(TaskContext));
				TaskEventRef = TGraphTask<FMeshDrawCommandInitResourcesTask>::CreateTask(&DependentGraphEvents, ENamedThreads::GetRenderThread()).ConstructAndDispatchWhenReady(TaskContext);
			}
		}
		else
		{
			QUICK_SCOPE_CYCLE_COUNTER(STAT_MeshPassSetupImmediate);
			FMeshDrawCommandPassSetupTask Task(TaskContext);
			Task.AnyThreadTask();
			if (!GAllowOnDemandShaderCreation || !RHISupportsMultithreadedShaderCreation(GMaxRHIShaderPlatform))
			{
				FMeshDrawCommandInitResourcesTask DependentTask(TaskContext);
				DependentTask.AnyThreadTask();
			}
		}
	}
}