vault backup: 2024-12-10 19:12:19
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@ -6,6 +6,8 @@ tags:
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rating: ⭐
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---
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# 阴影
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- [剖析虚幻渲染体系（05）- 光源和阴影](https://www.cnblogs.com/timlly/p/14817455.html)
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## 阴影类型
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- **Static Shadow**
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- **Cascading Shadow Map**
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@ -32,7 +34,168 @@ PS. UE5.3中相关逻辑移动到***CreateDynamicShadows()*** 中了。InitDynam
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- AddViewDependentWholeSceneShadowsForView()
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- SetupInteractionShadows()
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- ***CreatePerObjectProjectedShadow()***
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- InitProjectedShadowVisibility()
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丛越文章中的注释：
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```c++
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void FSceneRenderer::InitDynamicShadows(FRHICommandListImmediate& RHICmdList, FGlobalDynamicIndexBuffer& DynamicIndexBuffer, FGlobalDynamicVertexBuffer& DynamicVertexBuffer, FGlobalDynamicReadBuffer& DynamicReadBuffer)
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{
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// 初始化各类标记和数量.
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const bool bMobile = FeatureLevel < ERHIFeatureLevel::SM5;
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bool bStaticSceneOnly = false;
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for (int32 ViewIndex = 0; ViewIndex < Views.Num(); ViewIndex++)
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{
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FViewInfo& View = Views[ViewIndex];
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bStaticSceneOnly = bStaticSceneOnly || View.bStaticSceneOnly;
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}
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const bool bProjectEnablePointLightShadows = Scene->ReadOnlyCVARCache.bEnablePointLightShadows;
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uint32 NumPointShadowCachesUpdatedThisFrame = 0;
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uint32 NumSpotShadowCachesUpdatedThisFrame = 0;
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// 预计算阴影.
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TArray<FProjectedShadowInfo*,SceneRenderingAllocator> PreShadows;
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// 视图关联的全景阴影.
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TArray<FProjectedShadowInfo*,SceneRenderingAllocator> ViewDependentWholeSceneShadows;
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// 视图关联的需要裁剪的全景阴影.
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TArray<FProjectedShadowInfo*,SceneRenderingAllocator> ViewDependentWholeSceneShadowsThatNeedCulling;
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{
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// 遍历所有光源, 将不同类型的光源加入不同类型的待渲染的阴影列表中.
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for (TSparseArray<FLightSceneInfoCompact>::TConstIterator LightIt(Scene->Lights); LightIt; ++LightIt)
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{
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const FLightSceneInfoCompact& LightSceneInfoCompact = *LightIt;
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FLightSceneInfo* LightSceneInfo = LightSceneInfoCompact.LightSceneInfo;
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FScopeCycleCounter Context(LightSceneInfo->Proxy->GetStatId());
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FVisibleLightInfo& VisibleLightInfo = VisibleLightInfos[LightSceneInfo->Id];
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// LightOcclusionType有阴影图和光追两种, 如果非阴影图类型, 则忽略.
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const FLightOcclusionType OcclusionType = GetLightOcclusionType(LightSceneInfoCompact);
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if (OcclusionType != FLightOcclusionType::Shadowmap)
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continue;
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// 如果光源没有开启阴影或阴影质量太小, 则忽略阴影图.
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if ((LightSceneInfoCompact.bCastStaticShadow || LightSceneInfoCompact.bCastDynamicShadow) && GetShadowQuality() > 0)
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{
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// 检测该光源是否在某个view里可见, 如果不可见, 则忽略.
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bool bIsVisibleInAnyView = false;
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for (int32 ViewIndex = 0; ViewIndex < Views.Num(); ViewIndex++)
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{
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bIsVisibleInAnyView = LightSceneInfo->ShouldRenderLight(Views[ViewIndex]);
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if (bIsVisibleInAnyView)
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{
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break;
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}
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}
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// 所有裁剪条件都通过了, 处理光源的阴影.
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if (bIsVisibleInAnyView)
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{
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// 初始化阴影的各种标记和变量.
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static const auto AllowStaticLightingVar = IConsoleManager::Get().FindTConsoleVariableDataInt(TEXT("r.AllowStaticLighting"));
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const bool bAllowStaticLighting = (!AllowStaticLightingVar || AllowStaticLightingVar->GetValueOnRenderThread() != 0);
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// 是否点光源阴影. 注意矩形光也当做点光源处理.
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const bool bPointLightShadow = LightSceneInfoCompact.LightType == LightType_Point || LightSceneInfoCompact.LightType == LightType_Rect;
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// 对不预计算阴影的移动光源只创建全景阴影(whole scene shadow).
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const bool bShouldCreateShadowForMovableLight =
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LightSceneInfoCompact.bCastDynamicShadow
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&& (!LightSceneInfo->Proxy->HasStaticShadowing() || !bAllowStaticLighting);
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const bool bCreateShadowForMovableLight =
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bShouldCreateShadowForMovableLight
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&& (!bPointLightShadow || bProjectEnablePointLightShadows);
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// 对带有预计算阴影的尚未构建的光源创建全景阴影.
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const bool bShouldCreateShadowToPreviewStaticLight =
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LightSceneInfo->Proxy->HasStaticShadowing()
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&& LightSceneInfoCompact.bCastStaticShadow
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&& !LightSceneInfo->IsPrecomputedLightingValid();
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const bool bCreateShadowToPreviewStaticLight =
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bShouldCreateShadowToPreviewStaticLight
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&& (!bPointLightShadow || bProjectEnablePointLightShadows);
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// 对需要静态阴影但由于重叠导致没有有效阴影图的光源创建全景阴影.
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const bool bShouldCreateShadowForOverflowStaticShadowing =
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LightSceneInfo->Proxy->HasStaticShadowing()
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&& !LightSceneInfo->Proxy->HasStaticLighting()
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&& LightSceneInfoCompact.bCastStaticShadow
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&& LightSceneInfo->IsPrecomputedLightingValid()
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&& LightSceneInfo->Proxy->GetShadowMapChannel() == INDEX_NONE;
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const bool bCreateShadowForOverflowStaticShadowing =
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bShouldCreateShadowForOverflowStaticShadowing
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&& (!bPointLightShadow || bProjectEnablePointLightShadows);
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// 添加点光源的全景阴影.
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const bool bPointLightWholeSceneShadow = (bShouldCreateShadowForMovableLight || bShouldCreateShadowForOverflowStaticShadowing || bShouldCreateShadowToPreviewStaticLight) && bPointLightShadow;
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if (bPointLightWholeSceneShadow)
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{
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UsedWholeScenePointLightNames.Add(LightSceneInfoCompact.LightSceneInfo->Proxy->GetComponentName());
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}
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// 创建光源的全景阴影.
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if (bCreateShadowForMovableLight || bCreateShadowToPreviewStaticLight || bCreateShadowForOverflowStaticShadowing)
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{
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CreateWholeSceneProjectedShadow(LightSceneInfo, NumPointShadowCachesUpdatedThisFrame, NumSpotShadowCachesUpdatedThisFrame);
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}
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// 允许移动和固定的光源创建CSM(级联阴影), 或者是尚未构建的静态光源.
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if ((!LightSceneInfo->Proxy->HasStaticLighting() && LightSceneInfoCompact.bCastDynamicShadow) || bCreateShadowToPreviewStaticLight)
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{
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// 增加视图关联的全景阴影.
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if( !bMobile ||
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((LightSceneInfo->Proxy->UseCSMForDynamicObjects() || LightSceneInfo->Proxy->IsMovable())
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&& (LightSceneInfo == Scene->MobileDirectionalLights[0] || LightSceneInfo == Scene->MobileDirectionalLights[1] || LightSceneInfo == Scene->MobileDirectionalLights[2])))
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{
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AddViewDependentWholeSceneShadowsForView(ViewDependentWholeSceneShadows, ViewDependentWholeSceneShadowsThatNeedCulling, VisibleLightInfo, *LightSceneInfo);
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}
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// 处理交互阴影, 此处的交互是指光源和图元之间的影响. 包含PerObject阴影、透明阴影、自阴影等.
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if( !bMobile || (LightSceneInfo->Proxy->CastsModulatedShadows() && !LightSceneInfo->Proxy->UseCSMForDynamicObjects()))
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{
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Scene->FlushAsyncLightPrimitiveInteractionCreation();
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// 处理动态图元的交互阴影.
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for (FLightPrimitiveInteraction* Interaction = LightSceneInfo->GetDynamicInteractionOftenMovingPrimitiveList(false); Interaction; Interaction = Interaction->GetNextPrimitive())
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{
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SetupInteractionShadows(RHICmdList, Interaction, VisibleLightInfo, bStaticSceneOnly, ViewDependentWholeSceneShadows, PreShadows);
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}
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// 处理静态图元的交互阴影.
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for (FLightPrimitiveInteraction* Interaction = LightSceneInfo->GetDynamicInteractionStaticPrimitiveList(false); Interaction; Interaction = Interaction->GetNextPrimitive())
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{
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SetupInteractionShadows(RHICmdList, Interaction, VisibleLightInfo, bStaticSceneOnly, ViewDependentWholeSceneShadows, PreShadows);
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}
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}
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}
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}
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}
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}
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// 计算投射阴影的可见性.
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InitProjectedShadowVisibility(RHICmdList);
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}
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// 清理旧的预计算阴影, 尝试增加新的到缓存中.
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UpdatePreshadowCache(FSceneRenderTargets::Get(RHICmdList));
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// 收集图元列表, 以绘制不同类型的阴影.
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GatherShadowPrimitives(PreShadows, ViewDependentWholeSceneShadowsThatNeedCulling, bStaticSceneOnly);
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// 分配阴影深度渲染纹理.
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AllocateShadowDepthTargets(RHICmdList);
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// 收集阴影的动态网格元素, 跟之前剖析的GatherDynamicMeshElements类似.
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GatherShadowDynamicMeshElements(DynamicIndexBuffer, DynamicVertexBuffer, DynamicReadBuffer);
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}
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```
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### 阴影渲染
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# 阴影偏移
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@ -41,8 +204,8 @@ PS. UE5.3中相关逻辑移动到***CreateDynamicShadows()*** 中了。InitDynam
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- CustomDepth
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# 相关Paas
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1. ShadowDepths
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2. Lights
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1. ShadowDepths => RenderShadowDepthMaps()
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2. Lights => RenderLights()
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1. DirectLighting
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1. UnbatchedLights
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1. ShadowProjectionOnOpaque
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