vault backup: 2024-12-17 18:07:52

01-Diary/周小结/2024.12.md

@@ -24,3 +24,4 @@
 - [x] 帮助朱雨辰解决：
 	- [x] 4周年角色不能完全变黑问题。
 	- [x] 渲片时的天空球问题切换天空盒问题。
+- [ ] 

03-UnrealEngine/Rendering/RenderingPipeline/Materials&MeshDraw/MeshDraw.md

@@ -21,11 +21,6 @@ Shader推荐：
 - DepthOnlyVertexShader.usf
 - DepthOnlyPixelShader.usf
 
-# NaniteMeshDraw
-`Engine\Source\Runtime\Renderer\Private\Nanite\`NaniteMaterials.h & NaniteMaterials.cpp
-
-PS.使用的Shader必须是`FNaniteGlobalShader`的子类。
-
 ## BasePass
 ### DrawBasePass()
 该函数在FDeferredShadingSceneRenderer::RenderBasePassInternal()中调用。
@@ -256,3 +251,146 @@ FViewInfo& ViewInfo
 - GET_STATID(STAT_CLP_BasePass)
 	- FRDGParallelCommandListSet ParallelCommandListSet(InPass, RHICmdList, GET_STATID(STAT_CLP_BasePass), View, FParallelCommandListBindings(PassParameters));
 	- DECLARE_CYCLE_STAT(TEXT("BasePass"), STAT_CLP_BasePass, STATGROUP_ParallelCommandListMarkers);
+
+# NaniteMeshDraw
+`Engine\Source\Runtime\Renderer\Private\Nanite\`NaniteMaterials.h & NaniteMaterials.cpp
+
+PS.使用的Shader必须是`FNaniteGlobalShader`的子类。
+
+以下是Nanite物体的CustomDepth绘制过程：
+```c++
+bool FSceneRenderer::RenderCustomDepthPass(
+	FRDGBuilder& GraphBuilder,
+	FCustomDepthTextures& CustomDepthTextures,
+	const FSceneTextureShaderParameters& SceneTextures,
+	TConstArrayView<Nanite::FRasterResults> PrimaryNaniteRasterResults,
+	TConstArrayView<Nanite::FPackedView> PrimaryNaniteViews)
+{
+	if (!CustomDepthTextures.IsValid())
+	{
+		return false;
+	}
+
+	// Determine if any of the views have custom depth and if any of them have Nanite that is rendering custom depth
+	bool bAnyCustomDepth = false;
+	TArray<FNaniteCustomDepthDrawList, SceneRenderingAllocator> NaniteDrawLists;
+	NaniteDrawLists.AddDefaulted(Views.Num());
+	uint32 TotalNaniteInstances = 0;
+	for (int32 ViewIndex = 0; ViewIndex < Views.Num(); ++ViewIndex)
+	{
+		FViewInfo& View = Views[ViewIndex];
+		if (View.ShouldRenderView() && View.bHasCustomDepthPrimitives)
+		{
+			if (PrimaryNaniteRasterResults.IsValidIndex(ViewIndex))
+			{
+				const FNaniteVisibilityResults& VisibilityResults = PrimaryNaniteRasterResults[ViewIndex].VisibilityResults;
+
+				// Get the Nanite instance draw list for this view. (NOTE: Always use view index 0 for now because we're not doing
+				// multi-view yet).
+				NaniteDrawLists[ViewIndex] = BuildNaniteCustomDepthDrawList(View, 0u, VisibilityResults);
+
+				TotalNaniteInstances += NaniteDrawLists[ViewIndex].Num();
+			}
+			bAnyCustomDepth = true;
+		}
+	}
+
+	SET_DWORD_STAT(STAT_NaniteCustomDepthInstances, TotalNaniteInstances);
+..
+	if (TotalNaniteInstances > 0)
+	{
+		RDG_EVENT_SCOPE(GraphBuilder, "Nanite CustomDepth");
+
+		const FIntPoint RasterTextureSize = CustomDepthTextures.Depth->Desc.Extent;
+		FIntRect RasterTextureRect(0, 0, RasterTextureSize.X, RasterTextureSize.Y);
+		if (Views.Num() == 1)
+		{
+			const FViewInfo& View = Views[0];
+			if (View.ViewRect.Min.X == 0 && View.ViewRect.Min.Y == 0)
+			{
+				RasterTextureRect = View.ViewRect;
+			}
+		}
+
+		const bool bWriteCustomStencil = IsCustomDepthPassWritingStencil();
+
+		Nanite::FSharedContext SharedContext{};
+		SharedContext.FeatureLevel = Scene->GetFeatureLevel();
+		SharedContext.ShaderMap = GetGlobalShaderMap(SharedContext.FeatureLevel);
+		SharedContext.Pipeline = Nanite::EPipeline::Primary;
+
+		// TODO: If !bWriteCustomStencil, we could copy off the depth and rasterize depth-only (probable optimization)
+		Nanite::FRasterContext RasterContext = Nanite::InitRasterContext(
+			GraphBuilder,
+			SharedContext,
+			ViewFamily,
+			RasterTextureSize,
+			RasterTextureRect,
+			false, // bVisualize
+			Nanite::EOutputBufferMode::VisBuffer,
+			true, // bClearTarget
+			nullptr, // RectMinMaxBufferSRV
+			0, // NumRects
+			nullptr, // ExternalDepthBuffer
+			true // bCustomPass
+		);
+
+		Nanite::FCustomDepthContext CustomDepthContext = Nanite::InitCustomDepthStencilContext(
+			GraphBuilder,
+			CustomDepthTextures,
+			bWriteCustomStencil);
+
+		Nanite::FConfiguration CullingConfig = { 0 };
+		CullingConfig.bUpdateStreaming = true;
+
+		for (int32 ViewIndex = 0; ViewIndex < Views.Num(); ++ViewIndex)
+		{
+			RDG_EVENT_SCOPE_CONDITIONAL(GraphBuilder, Views.Num() > 1, "View%d", ViewIndex);
+
+			FViewInfo& View = Views[ViewIndex];
+
+			if (!View.ShouldRenderView() || NaniteDrawLists[ViewIndex].Num() == 0)
+			{
+				continue;
+			}
+
+			auto NaniteRenderer = Nanite::IRenderer::Create(
+				GraphBuilder,
+				*Scene,
+				View,
+				GetSceneUniforms(),
+				SharedContext,
+				RasterContext,
+				CullingConfig,
+				View.ViewRect,
+				/* PrevHZB = */ nullptr
+			);
+
+			NaniteRenderer->DrawGeometry(
+				Scene->NaniteRasterPipelines[ENaniteMeshPass::BasePass],
+				PrimaryNaniteRasterResults[ViewIndex].VisibilityResults,
+				*Nanite::FPackedViewArray::Create(GraphBuilder, PrimaryNaniteViews[ViewIndex]),
+				NaniteDrawLists[ViewIndex]
+			);
+
+			Nanite::FRasterResults RasterResults;
+			NaniteRenderer->ExtractResults( RasterResults );
+
+			// Emit depth
+			Nanite::EmitCustomDepthStencilTargets(
+				GraphBuilder,
+				*Scene,
+				View,
+				RasterResults.PageConstants,
+				RasterResults.VisibleClustersSWHW,
+				RasterResults.ViewsBuffer,
+				RasterContext.VisBuffer64,
+				CustomDepthContext
+			);
+		}
+
+		Nanite::FinalizeCustomDepthStencil(GraphBuilder, CustomDepthContext, CustomDepthTextures);
+	}
+...
+}
+```