BlueRoseNote/03-UnrealEngine/卡通渲染相关资料/渲染功能/ToonPostLightingPass/OutlinePass.md

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title	date	excerpt	tags	rating
未命名	2024-05-10 16:30:16			⭐

PostProcesss

void AddPostProcessingPasses(  
    FRDGBuilder& GraphBuilder,  
    const FViewInfo& View,   
int32 ViewIndex,  
    FSceneUniformBuffer& SceneUniformBuffer,  
    bool bAnyLumenActive,  
    bool bLumenGIEnabled,  
    EReflectionsMethod ReflectionsMethod,  
    const FPostProcessingInputs& Inputs,  
    const Nanite::FRasterResults* NaniteRasterResults,  
    FInstanceCullingManager& InstanceCullingManager,  
    FVirtualShadowMapArray* VirtualShadowMapArray,   
FLumenSceneFrameTemporaries& LumenFrameTemporaries,  
    const FSceneWithoutWaterTextures& SceneWithoutWaterTextures,  
    FScreenPassTexture TSRMoireInput)  
{  
    RDG_CSV_STAT_EXCLUSIVE_SCOPE(GraphBuilder, RenderPostProcessing);  
    QUICK_SCOPE_CYCLE_COUNTER(STAT_PostProcessing_Process);  
  
    check(IsInRenderingThread());  
    check(View.VerifyMembersChecks());  
    Inputs.Validate();  
  
    FScene* Scene = View.Family->Scene->GetRenderScene();  
  
    const FIntRect PrimaryViewRect = View.ViewRect;  
  
    const FSceneTextureParameters SceneTextureParameters = GetSceneTextureParameters(GraphBuilder, Inputs.SceneTextures);  
  
    const FScreenPassRenderTarget ViewFamilyOutput = FScreenPassRenderTarget::CreateViewFamilyOutput(Inputs.ViewFamilyTexture, View);  
    const FScreenPassTexture SceneDepth(SceneTextureParameters.SceneDepthTexture, PrimaryViewRect);  
    const FScreenPassTexture CustomDepth(Inputs.CustomDepthTexture, PrimaryViewRect);  
    const FScreenPassTexture Velocity(SceneTextureParameters.GBufferVelocityTexture, PrimaryViewRect);  
    const FScreenPassTexture BlackDummy(GSystemTextures.GetBlackDummy(GraphBuilder));  
    const FTranslucencyPassResources& PostDOFTranslucencyResources = Inputs.TranslucencyViewResourcesMap.Get(ETranslucencyPass::TPT_TranslucencyAfterDOF);  
    const FTranslucencyPassResources& PostMotionBlurTranslucencyResources = Inputs.TranslucencyViewResourcesMap.Get(ETranslucencyPass::TPT_TranslucencyAfterMotionBlur);

BasePass

#if WITH_EDITOR
	if (ViewFamily.EngineShowFlags.Wireframe)
	{
		checkf(ExclusiveDepthStencil.IsDepthWrite(), TEXT("Wireframe base pass requires depth-write, but it is set to read-only."));

		BasePassTextureCount = 1;
		BasePassTextures[0] = SceneTextures.EditorPrimitiveColor;
		BasePassTexturesView = MakeArrayView(BasePassTextures.GetData(), BasePassTextureCount);

		BasePassDepthTexture = SceneTextures.EditorPrimitiveDepth;

		auto* PassParameters = GraphBuilder.AllocParameters<FRenderTargetParameters>();
		PassParameters->RenderTargets = GetRenderTargetBindings(ERenderTargetLoadAction::EClear, BasePassTexturesView);
		PassParameters->RenderTargets.DepthStencil = FDepthStencilBinding(BasePassDepthTexture, ERenderTargetLoadAction::EClear, ERenderTargetLoadAction::EClear, ExclusiveDepthStencil);

		GraphBuilder.AddPass(RDG_EVENT_NAME("WireframeClear"), PassParameters, ERDGPassFlags::Raster, [](FRHICommandList&) {});
	}
#endif

	// Render targets bindings should remain constant at this point.
	FRenderTargetBindingSlots BasePassRenderTargets = GetRenderTargetBindings(ERenderTargetLoadAction::ELoad, BasePassTexturesView);
	BasePassRenderTargets.DepthStencil = FDepthStencilBinding(BasePassDepthTexture, ERenderTargetLoadAction::ELoad, ERenderTargetLoadAction::ELoad, ExclusiveDepthStencil);
	
	FForwardBasePassTextures ForwardBasePassTextures{};

	if (bForwardShadingEnabled)
	{
		ForwardBasePassTextures.SceneDepthIfResolved = SceneTextures.Depth.IsSeparate() ? SceneTextures.Depth.Resolve : nullptr;
		ForwardBasePassTextures.ScreenSpaceAO = SceneTextures.ScreenSpaceAO;
		ForwardBasePassTextures.ScreenSpaceShadowMask = ForwardShadowMaskTexture;
	}
	else if (!ExclusiveDepthStencil.IsDepthWrite())
	{
		// If depth write is not enabled, we can bound the depth texture as read only
		ForwardBasePassTextures.SceneDepthIfResolved = SceneTextures.Depth.Resolve;
	}
	ForwardBasePassTextures.bIs24BitUnormDepthStencil = ForwardBasePassTextures.SceneDepthIfResolved ? GPixelFormats[ForwardBasePassTextures.SceneDepthIfResolved->Desc.Format].bIs24BitUnormDepthStencil : 1;

	GraphBuilder.SetCommandListStat(GET_STATID(STAT_CLM_BasePass));
	RenderBasePassInternal(GraphBuilder, SceneTextures, BasePassRenderTargets, BasePassDepthStencilAccess, ForwardBasePassTextures, DBufferTextures, bDoParallelBasePass, bRenderLightmapDensity, InstanceCullingManager, bNaniteEnabled, NaniteRasterResults);
	GraphBuilder.SetCommandListStat(GET_STATID(STAT_CLM_AfterBasePass));



	FRenderTargetBindingSlots BasePassRenderTargets = GetRenderTargetBindings(ERenderTargetLoadAction::ELoad, BasePassTexturesView);
	BasePassRenderTargets.DepthStencil = FDepthStencilBinding(BasePassDepthTexture, ERenderTargetLoadAction::ELoad, ERenderTargetLoadAction::ELoad, ExclusiveDepthStencil);

	RenderBasePassInternal(GraphBuilder, SceneTextures, BasePassRenderTargets, BasePassDepthStencilAccess, ForwardBasePassTextures, DBufferTextures, bDoParallelBasePass, bRenderLightmapDensity, InstanceCullingManager, bNaniteEnabled, NaniteRasterResults);

读取GBufferTexture

位于SceneRendering.h

FORCEINLINE FSceneTextures& GetActiveSceneTextures() { return ViewFamily.GetSceneTextures(); }

考虑使用形参

• const FSceneTextures* SceneTextures
• const FSceneTextures& SceneTextures
• FSceneTextures& SceneTextures

UE5.4的FScreenTransform计算

参考：VisualizeMotionVectors.cpp

• FScreenTransform::SvPositionToViewportUV(Output.ViewRect)：SvPosition => ViewportUV
  • FScreenTransform SvPositionToViewportUV = FScreenTransform::SvPositionToViewportUV(Output.ViewRect);
• FScreenTransform::ViewportUVToScreenPos()：ViewportUV => ScreenPos
• FScreenTransform::ChangeTextureBasisFromTo()：坐标转换。比如下面的坐标是ViewportUV => TextureUV
  • FScreenTransform::ChangeTextureBasisFromTo(Inputs.SceneColor, FScreenTransform::ETextureBasis::ViewportUV, FScreenTransform::ETextureBasis::TextureUV);
• SvPosition => ScreenPos：SvPositionToViewportUV * FScreenTransform::ViewportUVToScreenPos

这是用于重采样后2个RT大小不一样而进行的计算。

OutlinePass

距离对于后处理深度描边的关系

需要针对极近距离进行处理。

• 最大深度采样值的最小值为100

距离	最小深度采样	最大深度采样
100cm	1	10
200cm	2	20
500cm	5	50
1000cm		100
2000cm
5000cm
10000cm

问题记录

处于FarDepthValue的Outline被裁剪的问题

• SkyAtmosphere.usf中，会将天空球渲染在深度为FarDepthValue的像素上，这样会将一些Outline覆盖掉。
• HeightFogPixelShader.usf中，会通过判断DeviceZ != 0.0 来调整渲染结果，绘制方式PSO.BlendState = TStaticBlendState<CW_RGB, BO_Add, BF_One, BF_SourceAlpha>::GetRHI();