412 lines
14 KiB
Markdown
412 lines
14 KiB
Markdown
---
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title: Untitled
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date: 2025-06-03 10:19:25
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excerpt:
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tags:
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rating: ⭐
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---
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# 前言
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1. ShaderWorldPCGInterop：
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2. ShaderWorld：
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3. ShaderWorldCore：
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# ShaderWorld
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- Class
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- Actor
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- ShaderWorldActor.h:[[#AShaderWorldActor]]
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- SWorld.h:[[#ASWorld]]
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## ASWorld
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## AShaderWorldActor
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## DrawMaterialToRenderTarget
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USWorldSubsystem::DrawMaterialToRenderTarget
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=>
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SWShaderToolBox::DrawMaterial
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=>
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DrawMaterial_CS_RT
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调用路径：
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- AShaderWorldActor::[[#RetrieveHeightAt]]（好像没有引用）：检索高度
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- AShaderWorldActor::ComputeHeight_Segmented_MapForClipMap
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- AShaderWorldActor::ProcessSegmentedComputation() <- AShaderWorldActor::TerrainAndSpawnablesManagement() <- AShaderWorldActor::Tick()
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- AShaderWorldActor::ComputeHeightMapForClipMap
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- AShaderWorldActor::UpdateClipMap() <- AShaderWorldActor::TerrainAndSpawnablesManagement() <- AShaderWorldActor::Tick()
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- AShaderWorldActor::ComputeDataLayersForClipMap
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- AShaderWorldActor::UpdateClipMap() <- AShaderWorldActor::TerrainAndSpawnablesManagement() <- AShaderWorldActor::Tick()
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- AShaderWorldActor::UpdateCollisionMeshData：更新碰撞模型数据。
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- AShaderWorldActor::CollisionGPU() <- AShaderWorldActor::CollisionManagement() <- AShaderWorldActor::Tick()
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- FSpawnableMesh::UpdateSpawnableData
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- AShaderWorldActor::ProcessSegmentedComputation() <- AShaderWorldActor::TerrainAndSpawnablesManagement() <- AShaderWorldActor::Tick()
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## Cache机制
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AShaderWorldActor::ProcessSegmentedComputation() <- AShaderWorldActor::TerrainAndSpawnablesManagement() <- AShaderWorldActor::Tick()
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# 其他Bug
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## SetTextureParameterValue相关逻辑排查
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- AShaderWorldActor中的SetTextureParameterValue
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- ~~ExportCacheInBounds~~
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- ~~AssignHeightMapToDynamicMaterial~~
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- UpdateStaticDataFor
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- ComputeHeight_Segmented_MapForClipMap：似乎会设置
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- ~~UpdateCollisionMeshData~~
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- [x] [[#InitializeReadBackDependencies]]
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- [x] InitiateMaterials
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### UpdateStaticDataFor
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### ComputeHeight_Segmented_MapForClipMap
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- 作用：
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- 调用顺序：AShaderWorldActor::Tick() -> AShaderWorldActor::TerrainAndSpawnablesManagement() -> AShaderWorldActor::ProcessSegmentedComputation() -> ComputeHeight_Segmented_MapForClipMap
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>// 1) Intersect clipmap with grid quad
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// 2) Gather non computed quads
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// 3) Allocated Compute element to missing Quad
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// 4) Update the indirection data to the new elements
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// 5) Update the Clipmap Heightmap with the grid data
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### UpdateCollisionMeshData
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- 作用：
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1. 判断DynCollisionMat是否有效，无效就使用`Generator`（高度数据生成材质）来创建。
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2. 设置材质参数NoMargin、TexelPerSide、PatchFullSize、MeshScale。
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3. 设置随机种子相关的材质参数。
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4. 设置材质参数PatchLocation。
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5. 生成碰撞数据到`CollisionRT`。
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6. 笔刷功能逻辑：ApplyBrushStackToHeightMap()。
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7. ExportPhysicalMaterialID逻辑。
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8. GPU碰撞数据回读：ShaderWorld::AsyncReadPixelsFromRT()。
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1. ShaderWorld::GSWReadbackManager.AddPendingReadBack()，将回读Task增加`TArray<FReadBackTask> PendingReads;`。
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2. 之后会在USWorldSubsystem::Tick()中调用ShaderWorld::GSWReadbackManager.TickReadBack()，不断检查是否可回读，并进行最终回读。
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- 调用顺序：Tick() -> CollisionManagement() -> CollisionGPU() -> UpdateCollisionMeshData()
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```c++
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namespace ShaderWorld
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{
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FORCEINLINE void AsyncReadPixelsFromRT(UShaderWorldRT2D* InRT, TSharedPtr<FSWColorRead, ESPMode::ThreadSafe> Destination, TSharedPtr < FThreadSafeBool, ESPMode::ThreadSafe> Completion)
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{
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ENQUEUE_RENDER_COMMAND(ReadGeoClipMapRTCmd)(
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[InRT, HeightData = Destination, Completion = Completion](FRHICommandListImmediate& RHICmdList)
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{
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check(IsInRenderingThread());
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if (HeightData.IsValid() && InRT->GetResource())
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{
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FRDGBuilder GraphBuilder(RHICmdList);
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TSharedPtr<FRHIGPUTextureReadback> ReadBackStaging = MakeShared<FRHIGPUTextureReadback>(TEXT("SWGPUTextureReadback"));
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FRDGTextureRef RDGSourceTexture = RegisterExternalTexture(GraphBuilder, InRT->GetResource()->TextureRHI, TEXT("SWSourceTextureToReadbackTexture"));
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AddEnqueueCopyPass(GraphBuilder, ReadBackStaging.Get(), RDGSourceTexture);
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GraphBuilder.Execute();
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ShaderWorld::GSWReadbackManager.AddPendingReadBack(RHICmdList, GPixelFormats[RDGSourceTexture->Desc.Format].BlockBytes, RDGSourceTexture->Desc.Extent.X, RDGSourceTexture->Desc.Extent.Y, ReadBackStaging, const_cast<TSharedPtr<FSWColorRead, ESPMode::ThreadSafe>&>(HeightData), const_cast<TSharedPtr < FThreadSafeBool, ESPMode::ThreadSafe>&>(Completion));
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}
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});
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}
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```
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### InitializeReadBackDependencies
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- 作用：初始化几个GPU数据回读用的RT。
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- 调用顺序：BeginPlay() -> InitiateWorld() -> InitializeReadBackDependencies()
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1. 初始化3个RT：ReadRequestLocation、ReadRequestLocationHeightmap、GeneratorDynamicForReadBack。
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2. 会设置`TObjectPtr < UMaterialInstanceDynamic> GeneratorDynamicForReadBack`各种变量
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```c++
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GeneratorDynamicForReadBack->SetScalarParameterValue("HeightReadBack", 1.f);
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GeneratorDynamicForReadBack->SetTextureParameterValue("SpecificLocationsRT", ReadRequestLocation);
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GeneratorDynamicForReadBack->SetScalarParameterValue("NoMargin", 0.f);
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GeneratorDynamicForReadBack->SetScalarParameterValue("N", N);
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GeneratorDynamicForReadBack->SetScalarParameterValue("NormalMapSelect", 0.f);
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GeneratorDynamicForReadBack->SetScalarParameterValue("HeightMapToggle", 1.f);
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```
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3. 设置随机种子相关Shader Parameter。
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### InitiateMaterials
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作用：初始化`TArray<FClipMapMeshElement> Meshes;`的Material、`Producers`
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调用顺序：BeginPlay() -> InitiateWorld() -> InitiateMaterials()
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经过断点调试，会设置WorldSettings里的Material（地形Material）的HeightMap与NormalMap。
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#
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SWorldSubsystem->DrawMaterialToRenderTarget
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# Rebuild逻辑
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## 重要函数
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- AShaderWorldActor::BeginPlay()
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- AShaderWorldActor::Setup()（<- TerrainAndSpawnablesManagement(float& DeltaT) <- Tick()）
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## Rebuild逻辑顺序
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1. AShaderWorldActor::BeginPlay()
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1.
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# Debug
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1. AShaderWorldActor::ComputeHeight_Segmented_MapForClipMap 十多次
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2. UpdateCollisionMeshData
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3. AShaderWorldActor::ComputeHeight_Segmented_MapForClipMap 十多次
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4. [[#RetrieveHeightAt]]
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5. UpdateCollisionMeshData 3次
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6. AShaderWorldActor::ComputeHeight_Segmented_MapForClipMap 十多次
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# RetrieveHeightAt
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可能存在bug待排查的：
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- ShaderWorldSubsystem->LoadSampleLocationsInRT()
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- ShaderWorldSubsystem->DrawMaterialToRenderTarget()
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## 相关变量
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- FThreadSafeBool
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- bProcessingHeightRetrieval
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- bProcessingHeightRetrievalRT
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- MID
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- GeneratorDynamicForReadBack
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- UShaderWorldRT2D（`UTextureRenderTarget2D`）
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- ReadRequestLocation：RTF_RG32f，初始化于`InitializeReadBackDependencies() <- InitiateWorld()`
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- ReadRequestLocationHeightmap：RTF_RGBA8，初始化于`InitializeReadBackDependencies() <- InitiateWorld()`
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## 代码
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```c++
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bool AShaderWorldActor::RetrieveHeightAt(const TArray<FVector>& Origin, const FSWHeightRetrievalDelegate& Callback)
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{
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if (!GeneratorDynamicForReadBack || !SWorldSubsystem)
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return false;
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if (!bProcessingHeightRetrieval.IsValid())
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{
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bProcessingHeightRetrieval = MakeShared<FThreadSafeBool, ESPMode::ThreadSafe>();
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bProcessingHeightRetrieval->AtomicSet(false);
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}
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if (!bProcessingHeightRetrievalRT.IsValid())
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{
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bProcessingHeightRetrievalRT = MakeShared<FThreadSafeBool, ESPMode::ThreadSafe>();
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bProcessingHeightRetrievalRT->AtomicSet(false);
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}
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if (!(*bProcessingHeightRetrieval.Get()) && ReadRequestLocation && ReadRequestLocationHeightmap && GeneratorDynamicForReadBack)
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{
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bProcessingHeightRetrieval->AtomicSet(true);
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bProcessingHeightRetrievalRT->AtomicSet(false);
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HeightRetrieveDelegate = Callback;
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//初始化采样点数组结构体FSWShareableSamplePoints
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PointsPendingReadBacks = MakeShared<FSWShareableSamplePoints, ESPMode::ThreadSafe>();
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TSharedPtr<FSWShareableSamplePoints>& Samples = PointsPendingReadBacks;
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FBox BoundingBoxRead(Origin);
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Samples->PositionsXY.SetNum(25 * 2);
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for (int i = 0; i < 25; i++)
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{
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if (i < Origin.Num())
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{
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Samples->PositionsXY[i * 2] = Origin[i].X;
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Samples->PositionsXY[i * 2 + 1] = Origin[i].Y;
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}
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else
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{
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Samples->PositionsXY[i * 2] = 0.f;
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Samples->PositionsXY[i * 2 + 1] = 0.f;
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}
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}
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if (USWorldSubsystem* ShaderWorldSubsystem = SWorldSubsystem)
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{
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//从渲染线程
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ShaderWorldSubsystem->LoadSampleLocationsInRT(ReadRequestLocation, Samples);
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#if SW_COMPUTE_GENERATION
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ShaderWorldSubsystem->DrawMaterialToRenderTarget(
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{ false,
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false,
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GetWorld()->Scene,
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(float)GetWorld()->TimeSeconds,
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false,
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true,
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ReadRequestLocationHeightmap->SizeX,
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10,
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FVector(0.f),
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true,
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ReadRequestLocation,
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GeneratorDynamicForReadBack,
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ReadRequestLocationHeightmap
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});
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#else
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UKismetRenderingLibrary::DrawMaterialToRenderTarget(this, ReadRequestLocationHeightmap, GeneratorDynamicForReadBack);
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#endif
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int32 Size_RT_Readback = ReadRequestLocationHeightmap.Get()->SizeX;
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FVector Barycentre = BoundingBoxRead.GetCenter();
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FVector Extent = BoundingBoxRead.GetExtent();
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float gridspacing = Extent.X * 2.0 / (Size_RT_Readback - 1);
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if (IsValid(BrushManager))
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BrushManager->ApplyBrushStackToHeightMap(this, 0, ReadRequestLocationHeightmap.Get(), Barycentre, gridspacing, Size_RT_Readback, true, true, ReadRequestLocation.Get());
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ReadBackHeightData = MakeShared<FSWColorRead, ESPMode::ThreadSafe>();
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ReadBackHeightData->ReadData.SetNum(25);
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ENQUEUE_RENDER_COMMAND(ReadGeoClipMapRTCmd)(
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[InRT = ReadRequestLocationHeightmap, HeightData = ReadBackHeightData, Completion = bProcessingHeightRetrievalRT](FRHICommandListImmediate& RHICmdList)
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{
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check(IsInRenderingThread());
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if (HeightData.IsValid() && InRT->GetResource())
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{
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FRDGBuilder GraphBuilder(RHICmdList);
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TSharedPtr<FRHIGPUTextureReadback> ReadBackStaging = MakeShared<FRHIGPUTextureReadback>(TEXT("SWGPUTextureReadback"));
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FRDGTextureRef RDGSourceTexture = RegisterExternalTexture(GraphBuilder, InRT->GetResource()->TextureRHI, TEXT("SWSourceTextureToReadbackTexture"));
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AddEnqueueCopyPass(GraphBuilder, ReadBackStaging.Get(), RDGSourceTexture);
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GraphBuilder.Execute();
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ShaderWorld::GSWReadbackManager.AddPendingReadBack(RHICmdList, GPixelFormats[RDGSourceTexture->Desc.Format].BlockBytes, RDGSourceTexture->Desc.Extent.X, RDGSourceTexture->Desc.Extent.Y, ReadBackStaging, const_cast<TSharedPtr<FSWColorRead, ESPMode::ThreadSafe>&>(HeightData), const_cast<TSharedPtr < FThreadSafeBool, ESPMode::ThreadSafe>&>(Completion));
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}
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});
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HeightReadBackFence.BeginFence(true);
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}
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return true;
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}
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return false;
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}
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```
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### RequestReadBackLoad
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```c++
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bool USWorldSubsystem::LoadSampleLocationsInRT(UShaderWorldRT2D* LocationsRequestedRT,
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TSharedPtr<FSWShareableSamplePoints>& Samples)
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{
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if (!RenderThreadResponded)
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return false;
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const SWSampleRequestComputeData ReadBackData(LocationsRequestedRT, Samples);
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SWToolBox->RequestReadBackLoad(ReadBackData);
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return true;
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}
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```
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# SWShaderToolBox
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## RequestReadBackLoad
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```c++
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void SWShaderToolBox::RequestReadBackLoad(const SWSampleRequestComputeData& Data) const
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{
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if (Data.CPU)
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return CPUTools.RequestReadBackLoad(Data);
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ENQUEUE_RENDER_COMMAND(ShaderTools_copy_rt)
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([this, Data](FRHICommandListImmediate& RHICmdList)
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{
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if (Data.SamplesXY && Data.SamplesXY->GetResource())
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RequestReadBackLoad_RT(RHICmdList,Data);
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}
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);
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}
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void SWShaderToolBox::RequestReadBackLoad_RT(FRHICommandListImmediate& RHICmdList, const SWSampleRequestComputeData& Data) const
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{
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if (!(Data.SamplesXY && Data.SamplesXY->GetResource()))
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return;
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FRDGBuilder GraphBuilder(RHICmdList);
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{
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RDG_EVENT_SCOPE(GraphBuilder, "ShaderWorld PositionReadBack");
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RDG_GPU_STAT_SCOPE(GraphBuilder, ShaderWorldReadBack);
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FIntVector GroupCount;
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GroupCount.X = FMath::DivideAndRoundUp((float)Data.SamplesXY->GetResource()->GetSizeX(), (float)SW_LoadReadBackLocations_GroupSizeX);
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GroupCount.Y = FMath::DivideAndRoundUp((float)Data.SamplesXY->GetResource()->GetSizeY(), (float)SW_LoadReadBackLocations_GroupSizeY);
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GroupCount.Z = 1;
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const FUnorderedAccessViewRHIRef RT_UAV = GraphBuilder.RHICmdList.CreateUnorderedAccessView(Data.SamplesXY->GetResource()->TextureRHI);
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const FRDGBufferRef LocationRequest = CreateUploadBuffer(
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GraphBuilder,
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TEXT("SWLoadSampleLocations"),
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sizeof(float),
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Data.SamplesSource->PositionsXY.Num(),
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Data.SamplesSource->PositionsXY.GetData(),
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Data.SamplesSource->PositionsXY.Num() * Data.SamplesSource->PositionsXY.GetTypeSize()
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);
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const FRDGBufferSRVRef LocationRequestSRV = GraphBuilder.CreateSRV(FRDGBufferSRVDesc(LocationRequest, PF_R32_FLOAT));;
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FLoadReadBackLocations_CS::FPermutationDomain PermutationVector;
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TShaderMapRef<FLoadReadBackLocations_CS> ComputeShader(GetGlobalShaderMap(GMaxRHIFeatureLevel), PermutationVector);
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FLoadReadBackLocations_CS::FParameters* PassParameters = GraphBuilder.AllocParameters<FLoadReadBackLocations_CS::FParameters>();
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PassParameters->SampleDim = Data.SamplesXY->GetResource()->GetSizeX();
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PassParameters->DestLocationsTex = RT_UAV;
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PassParameters->SourceLocationBuffer = LocationRequestSRV;
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GraphBuilder.AddPass(
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RDG_EVENT_NAME("ShaderWorld LoadReadBacklocations_CS"),
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PassParameters,
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ERDGPassFlags::Compute |
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ERDGPassFlags::NeverCull,
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[PassParameters, ComputeShader, GroupCount](FRHICommandList& RHICmdList)
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{
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FComputeShaderUtils::Dispatch(RHICmdList, ComputeShader, *PassParameters, GroupCount);
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});
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}
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GraphBuilder.Execute();
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}
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```
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FLoadReadBackLocations_CS
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```c++
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uint SampleDim;
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RWTexture2D<float2> DestLocationsTex;
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Buffer<float> SourceLocationBuffer;
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[numthreads(THREADGROUP_SIZEX, THREADGROUP_SIZEY, THREADGROUP_SIZEZ)]
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void SampleLocationLoaderCS(uint3 ThreadId : SV_DispatchThreadID)
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{
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if (any(ThreadId.xy >= SampleDim.xx))
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return;
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uint IndexPixel = (ThreadId.x + ThreadId.y * SampleDim) * 2;
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DestLocationsTex[ThreadId.xy] = float2(SourceLocationBuffer[IndexPixel],SourceLocationBuffer[IndexPixel + 1]);
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}
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```
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#
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- M_Blank_HeightLayer
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- MFC_WorldPositionNormal_Layer
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- M_Blank_HeightLayer（未连接）
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- MFC_Position_ForCache
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- 其他
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- MF_CacheRead_Reference_Tessellation
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- MFC_CacheRead：没有其他引用
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- MFC_CacheRead_Tessellationt
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- MFC_CacheReadNoVertexManipulation
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- MFC_ExternalCacheRead |