vault backup: 2024-12-19 15:13:04

03-UnrealEngine/Rendering/RenderingPipeline/Lighting/Shadow.md

@@ -436,6 +436,29 @@ bool FShadowDepthPassMeshProcessor::TryAddMeshBatch(const FMeshBatch& RESTRICT M
 }
 ```
 
+## ShaderDepthBias
+相关计算位于FProjectedShadowInfo::UpdateShaderDepthBias()。
+起效条件：勾选Dynamic Inset Shadow
+CMD: CVarPerObjectDirectionalShadowDepthBias => r.Shadow.PerObjectDirectionalDepthBias 
+```c++
+// per object shadows (the whole-scene are taken care of above)
+if(bDirectionalLight)
+{
+	// we use CSMShadowDepthBias cvar but this is per object shadows, maybe we want to use different settings
+
+	// the z range is adjusted to we need to adjust here as well
+	DepthBias = CVarPerObjectDirectionalShadowDepthBias.GetValueOnRenderThread() / (MaxSubjectZ - MinSubjectZ);
+
+	float WorldSpaceTexelScale = ShadowBounds.W / FMath::Max(ResolutionX, ResolutionY);
+
+	DepthBias *= WorldSpaceTexelScale;
+	DepthBias *= 0.5f;	// avg GetUserShadowBias, in that case we don't want this adjustable
+
+	SlopeScaleDepthBias = CVarPerObjectDirectionalShadowSlopeScaleDepthBias.GetValueOnRenderThread();
+	SlopeScaleDepthBias *= LightSceneInfo->Proxy->GetUserShadowSlopeBias();
+}
+```
+
 ## Shader
 VertexShader为：ShadowDepthVertexShader.usf，有4种变体：
 - IMPLEMENT_SHADOW_DEPTH_SHADERMODE_SHADERS(VertexShadowDepth_PerspectiveCorrect);