Lumen Directlighting CombineLighting

Engine/Source/Runtime/Renderer/Private/Lumen/LumenSceneLighting.cpp

cpp 复制代码

void Lumen::CombineLumenSceneLighting(
	FScene* Scene,
	const FViewInfo& View,
	FRDGBuilder& GraphBuilder,
	const FLumenCardTracingInputs& TracingInputs,
	const FLumenCardUpdateContext& CardUpdateContext,
	const FLumenCardTileUpdateContext& CardTileUpdateContext,
	ERDGPassFlags ComputePassFlags)
{
	LLM_SCOPE_BYTAG(Lumen);
	FLumenSceneData& LumenSceneData = *Scene->GetLumenSceneData(View);

	FLumenCardCombineLightingCS::FParameters* PassParameters = GraphBuilder.AllocParameters<FLumenCardCombineLightingCS::FParameters>();
	PassParameters->IndirectArgsBuffer = CardTileUpdateContext.DispatchCardTilesIndirectArgs;
	PassParameters->View = View.ViewUniformBuffer;
	PassParameters->LumenCardScene = TracingInputs.LumenCardSceneUniformBuffer;
	PassParameters->DiffuseColorBoost = 1.0f / FMath::Max(View.FinalPostProcessSettings.LumenDiffuseColorBoost, 1.0f);
	PassParameters->AlbedoAtlas = TracingInputs.AlbedoAtlas;
	PassParameters->OpacityAtlas = TracingInputs.OpacityAtlas;
	PassParameters->EmissiveAtlas = TracingInputs.EmissiveAtlas;
	PassParameters->DirectLightingAtlas = TracingInputs.DirectLightingAtlas;
	PassParameters->IndirectLightingAtlas = TracingInputs.IndirectLightingAtlas;
	PassParameters->BilinearClampedSampler = TStaticSamplerState<SF_Bilinear, AM_Clamp, AM_Clamp, AM_Clamp>::GetRHI();
	PassParameters->CardTiles = GraphBuilder.CreateSRV(CardTileUpdateContext.CardTiles);
	PassParameters->RWFinalLightingAtlas = GraphBuilder.CreateUAV(TracingInputs.FinalLightingAtlas);
	const FIntPoint IndirectLightingAtlasSize = LumenSceneData.GetRadiosityAtlasSize();
	PassParameters->IndirectLightingAtlasHalfTexelSize = FVector2f(0.5f / IndirectLightingAtlasSize.X, 0.5f / IndirectLightingAtlasSize.Y);

	auto ComputeShader = View.ShaderMap->GetShader<FLumenCardCombineLightingCS>();

	FComputeShaderUtils::AddPass(
		GraphBuilder,
		RDG_EVENT_NAME("CombineLighting CS"),
		ComputePassFlags,
		ComputeShader,
		PassParameters,
		CardTileUpdateContext.DispatchCardTilesIndirectArgs,
		(uint32)ELumenDispatchCardTilesIndirectArgsOffset::OneGroupPerCardTile);
}

LumenSceneLighting.usf

cpp 复制代码

SamplerState BilinearClampedSampler;
StructuredBuffer<uint> CardTiles;
RWTexture2D<float3> RWFinalLightingAtlas;


[numthreads( 8 ,  8 , 1)]
void CombineLumenSceneLightingCS(
	uint3 GroupId : SV_GroupID,
	uint3 GroupThreadId : SV_GroupThreadID)
{
	uint CardTileIndex = GroupId.x;
	uint2 TexelCoordInTile = GroupThreadId.xy;

	FCardTileData CardTile = UnpackCardTileData(CardTiles[CardTileIndex]);

	FLumenCardPageData CardPage = GetLumenCardPageData(CardTile.CardPageIndex);
	FLumenCardData Card = GetLumenCardData(CardPage.CardIndex);

	uint2 CoordInCardPage =  8  * CardTile.TileCoord + TexelCoordInTile;
	uint2 AtlasCoord = CardPage.PhysicalAtlasCoord + CoordInCardPage;
	float2 AtlasUV = CardPage.PhysicalAtlasUVRect.xy + CardPage.PhysicalAtlasUVTexelScale * (CoordInCardPage + 0.5);


	float2 IndirectLightingAtlasUV = AtlasUV;





	float3 Albedo = Texture2DSampleLevel(AlbedoAtlas, BilinearClampedSampler, AtlasUV, 0).xyz;
	float3 Emissive = Texture2DSampleLevel(EmissiveAtlas, BilinearClampedSampler, AtlasUV, 0).xyz;
	float3 DirectLighting = Texture2DSampleLevel(DirectLightingAtlas, BilinearClampedSampler, AtlasUV, 0).xyz;
	float3 IndirectLighting = Texture2DSampleLevel(IndirectLightingAtlas, BilinearClampedSampler, IndirectLightingAtlasUV, 0).xyz;

	float3 FinalLighting = CombineFinalLighting(Albedo, Emissive, DirectLighting, IndirectLighting);
	RWFinalLightingAtlas[AtlasCoord] = FinalLighting;
}


float3 CombineFinalLighting(float3 Albedo, float3 Emissive, float3 DirectLighting, float3 IndirectLighting)
{
	Albedo = DecodeSurfaceCacheAlbedo(Albedo);

	float3 FinalLighting = (DirectLighting + IndirectLighting) * Diffuse_Lambert(Albedo) + Emissive;


	FinalLighting = max(MakeFinite(FinalLighting), float3(0.0f, 0.0f, 0.0f));

	return FinalLighting;
}


float3 DecodeSurfaceCacheAlbedo(float3 EncodedAlbedo)
{
	float3 Albedo = EncodedAlbedo * EncodedAlbedo;


	Albedo = min(saturate(pow(Albedo, DiffuseColorBoost)), 0.99f);

	return Albedo;
}