128 lines
4.9 KiB
Markdown
128 lines
4.9 KiB
Markdown
---
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title: Untitled
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date: 2024-12-08 12:18:54
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excerpt:
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tags:
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rating: ⭐
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---
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# 阴影
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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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- **Per Object Shadow**：可移动组件使用的逐物体阴影应用阴影图到物体的包围盒，因此包围盒必须是精确的。对于骨骼网格，这意味着它们应该有一个物理资产。对于粒子系统，任何固定的边界框必须足够大，以容纳所有的粒子。_在网格的Lighting属性组中，Dynamic Inset Shadow可以开启逐物体阴影，对需要高质量高精度的物体非常有用。_
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- **Dynamic Shadow**：可移动光源在所有物体上投射出完全动态的阴影(和光)。这种光源的任何数据不会被烘焙到光照图中，它可以自由地在所有东西上投射动态阴影。静态网格、骨架网格、粒子效果等等将完全从可移动光源投射和接收动态阴影。
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- **Capsule Shadow**
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- **Contact Shadow**
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- **Distance Field Shadow**
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## 相关类型
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- ShadowRendering.h
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**FProjectedShadowInfo**：存储投影阴影先关信息。包含各种变换矩阵、阴影渲染函数以及渲染参数、灯光&场景&图元信息。
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- SceneRendering.h
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FVisibleLightInfo：可见光源信息, 主要是阴影相关的信息.
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FVisibleLightViewInfo：
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## DynamicShadows
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### InitDynamicShadows() => CreateDynamicShadows()
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InitViews() => FSceneRenderer::InitDynamicShadows()
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PS. UE5.3中相关逻辑移动到***CreateDynamicShadows()*** 中了。InitDynamicShadows() => BeginInitDynamicShadows() => BeginGatherShadowPrimitives() => CreateDynamicShadows()
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计算各种灯光类型，之后调用：
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- CreateWholeSceneProjectedShadow()
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- AddViewDependentWholeSceneShadowsForView()
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- SetupInteractionShadows()
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### CreateWholeSceneProjectedShadow
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# 阴影偏移
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可以考虑的Buffer有
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- ShadowDepths
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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. DirectLighting
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1. UnbatchedLights
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1. ShadowProjectionOnOpaque
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# ShadowDepths
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- FSceneRenderer::RenderShadowDepthMaps()：位于CustomDepth之前。
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- RenderVirtualShadowMaps()
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- RenderShadowDepthMapAtlases()
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- SortedShadowsForShadowDepthPass.ShadowMapCubemaps循环
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-
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# Lights
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### Shader
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ShadowProjectionPixelShader.usf
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- TShadowProjectionPS：
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- TDirectionalPercentageCloserShadowProjectionPS：方向光投影
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- TSpotPercentageCloserShadowProjectionPS：SpotLight
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- FOnePassPointShadowProjectionPS(Moible?)
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### 相关函数
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- FDeferredShadingSceneRenderer::RenderLights()
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- FDeferredShadingSceneRenderer::RenderDeferredShadowProjections()
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- FSceneRenderer::RenderShadowProjections()
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- FProjectedShadowInfo::SetupFrustumForProjection()：构建阴影投影4棱椎平面信息。
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- FProjectedShadowInfo::SetupProjectionStencilMask()：
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# 其他
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顺序：
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RenderCustomDepthPass
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FSceneRenderer::CreateDynamicShadows
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=>
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FSceneRenderer::CreatePerObjectProjectedShadow
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```c++
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if (!IsForwardShadingEnabled(ShaderPlatform))
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{
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// Dynamic shadows are synced later when using the deferred path to make more headroom for tasks.
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FinishInitDynamicShadows(GraphBuilder, InitViewTaskDatas.DynamicShadows, InstanceCullingManager, ExternalAccessQueue);
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}
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```
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```c++
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if (RendererOutput == ERendererOutput::DepthPrepassOnly)
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{
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RenderOcclusionLambda();
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if (bUpdateNaniteStreaming)
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{
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Nanite::GStreamingManager.SubmitFrameStreamingRequests(GraphBuilder);
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}
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CopySceneCaptureComponentToTarget(GraphBuilder, SceneTextures, ViewFamilyTexture, ViewFamily, Views);
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}
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else
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{
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GVRSImageManager.PrepareImageBasedVRS(GraphBuilder, ViewFamily, SceneTextures);
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if (!IsForwardShadingEnabled(ShaderPlatform))
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{
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// Dynamic shadows are synced later when using the deferred path to make more headroom for tasks.
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FinishInitDynamicShadows(GraphBuilder, InitViewTaskDatas.DynamicShadows, InstanceCullingManager, ExternalAccessQueue);
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}
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// Update groom only visible in shadow
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if (IsHairStrandsEnabled(EHairStrandsShaderType::All, Scene->GetShaderPlatform()) && RendererOutput == ERendererOutput::FinalSceneColor)
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{
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UpdateHairStrandsBookmarkParameters(Scene, Views, HairStrandsBookmarkParameters);
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// Interpolation for cards/meshes only visible in shadow needs to happen after the shadow jobs are completed
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const bool bRunHairStrands = HairStrandsBookmarkParameters.HasInstances() && (Views.Num() > 0);
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if (bRunHairStrands)
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{
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RunHairStrandsBookmark(GraphBuilder, EHairStrandsBookmark::ProcessCardsAndMeshesInterpolation_ShadowView, HairStrandsBookmarkParameters);
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}
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}
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// NOTE: The ordering of the lights is used to select sub-sets for different purposes, e.g., those that support clustered deferred.
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FSortedLightSetSceneInfo& SortedLightSet = *GraphBuilder.AllocObject<FSortedLightSetSceneInfo>();
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{
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RDG_CSV_STAT_EXCLUSIVE_SCOPE(GraphBuilder, SortLights);
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RDG_GPU_STAT_SCOPE(GraphBuilder, SortLights);
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ComputeLightGridOutput = GatherLightsAndComputeLightGrid(GraphBuilder, bComputeLightGrid, SortedLightSet);
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}
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``` |