1.创建cardUpdateContext
2,。直接光照
3. 间接光照
context
1. 清除数据：ClearCardUpdateContextCS
/**
* Batch clear all resources required for the subsequent card context update pass
*/
[numthreads(THREADGROUP_SIZE, 1, 1)]
void ClearCardUpdateContextCS(
uint3 DispatchThreadId : SV_DispatchThreadID)
{
uint ElementIndex = DispatchThreadId.x;
if (ElementIndex < 1)
{
RWDirectLightingCardPageIndexAllocator[ElementIndex] = 0;
RWIndirectLightingCardPageIndexAllocator[ElementIndex] = 0;
}
if (ElementIndex < CARD_UPDATE_CONTEXT_MAX * MAX_UPDATE_BUCKET_STRIDE)
{
RWMaxUpdateBucket[ElementIndex] = 0;
}
if (ElementIndex < CARD_UPDATE_CONTEXT_MAX * CARD_PAGE_TILE_ALLOCATOR_STRIDE)
{
RWCardPageTileAllocator[ElementIndex] = 0;
}
if (ElementIndex < CARD_UPDATE_CONTEXT_MAX * PRIORITY_HISTOGRAM_SIZE)
{
RWPriorityHistogram[ElementIndex] = 0;
}
}
2. page更新直方图
BuildPageUpdatePriorityHistogram
[numthreads(THREADGROUP_SIZE, 1, 1)]
void BuildPageUpdatePriorityHistogramCS(
uint3 DispatchThreadId : SV_DispatchThreadID)
{
uint IndexInIndexBuffer = DispatchThreadId.x;
if (IndexInIndexBuffer < CardPageNum)
{
uint CardPageIndex = IndexInIndexBuffer;
FLumenCardPageData CardPage = GetLumenCardPageData(CardPageIndex);
FLumenCardData Card = GetLumenCardData(CardPage.CardIndex);
const uint NumCardPageTiles = GetNumCardPageTiles(CardPage);
if (NumCardPageTiles > 0)
{
BuildUpdatePriorityHistogram(Card, CardPage, CardPageIndex, NumCardPageTiles, CARD_UPDATE_CONTEXT_DIRECT_LIGHTING);
BuildUpdatePriorityHistogram(Card, CardPage, CardPageIndex, NumCardPageTiles, CARD_UPDATE_CONTEXT_INDIRECT_LIGHTING);
}
}
}
优先级的计算
uint GetPriorityBucketIndex(FLumenCardData Card, FLumenCardPageData CardPage, uint CardPageIndex, uint CardUpdateContext)
{
const float MaxUpdateFrequency = 7.0f;
uint LastLightingUpdateFrameIndex = GetLastLightingUpdateFrameIndex(CardPage, CardUpdateContext);
const float UpdateFactor = GetUpdateFactor(CardUpdateContext);
// [1;N]
uint FramesSinceLastUpdated = SurfaceCacheUpdateFrameIndex - LastLightingUpdateFrameIndex;
// [0;MaxUpdateFrequency]
float Frequency = 0.0f;
{
float DistanceFromViewer = 100000000.0f;
for (uint ViewIndex = 0; ViewIndex < NumCameraOrigins; ViewIndex++)
{
float3 CardSpaceViewPosition = mul(WorldCameraOrigins[ViewIndex].xyz - Card.Origin, Card.WorldToLocalRotation);
float3 CardPageLocalCenter;
float3 CardPageLocalExtent;
GetCardPageLocalBBox(CardPage, Card, CardPageLocalCenter, CardPageLocalExtent);
DistanceFromViewer = min(DistanceFromViewer, sqrt(ComputeSquaredDistanceFromBoxToPoint(CardPageLocalCenter, CardPageLocalExtent, CardSpaceViewPosition)));
}
Frequency = MaxUpdateFrequency - clamp(DistanceFromViewer * FirstClipmapWorldExtentRcp, 0.0f, MaxUpdateFrequency);
}
// Drive frequency based on the feedback
#if SURFACE_CACHE_FEEDBACK
{
const uint LastUsedFrameIndex = CardPageLastUsedBuffer[CardPageIndex];
const uint LastUsedHighResFrameIndex = CardPageHighResLastUsedBuffer[CardPageIndex];
const uint LastUsedCombinedFrameIndex = max(LastUsedFrameIndex, LastUsedHighResFrameIndex);
FramesSinceLastUpdated = LastUsedCombinedFrameIndex > LastLightingUpdateFrameIndex ? LastUsedCombinedFrameIndex - LastLightingUpdateFrameIndex : 1;
Frequency *= 0.5f;
if (SurfaceCacheUpdateFrameIndex >= LastUsedHighResFrameIndex + 1)
{
Frequency += 0.5f * MaxUpdateFrequency * saturate((SurfaceCacheUpdateFrameIndex - (LastUsedHighResFrameIndex + 1)) / 2.0f);
}
}
#endif
uint BucketIndex = 0;
if (LastLightingUpdateFrameIndex == 0)
{
// Special case where page wasn't ever updated, just place into first 8 most important buckets based on the frequency
BucketIndex = clamp(MaxUpdateFrequency - Frequency, 0.0f, MaxUpdateFrequency);
}
else
{
// [0;N]
float UpdateImportance = FramesSinceLastUpdated * (Frequency + 1.0f);
// Offset from [1;N] and invert in order to place most important pages in bucket 0
BucketIndex = PRIORITY_HISTOGRAM_SIZE - 1 - clamp(log2(UpdateImportance / (MaxUpdateFrequency + 1.0f)), 0, PRIORITY_HISTOGRAM_SIZE - 1);
}
return BucketIndex;
}
void BuildUpdatePriorityHistogram(FLumenCardData Card, FLumenCardPageData CardPage, uint CardPageIndex, uint NumCardPageTiles, uint CardUpdateContext)
{
uint PriorityBucketIndex = GetPriorityBucketIndex(Card, CardPage, CardPageIndex, CardUpdateContext);
InterlockedAdd(RWPriorityHistogram[CardUpdateContext * PRIORITY_HISTOGRAM_SIZE + PriorityBucketIndex], NumCardPageTiles);
}
3.最大优先级的找到
SelectMaxUpdateBucketCS
void SelectMaxUpdateBucket(uint CardUpdateContext)
{
const uint MaxTilesToUpdate = GetMaxTilesToUpdate(CardUpdateContext);
uint UpdateTileSum = 0;
uint PriorityBucketIndex = 0;
uint PriorityBucketMaxTiles = MaxTilesToUpdate;
for (; PriorityBucketIndex < PRIORITY_HISTOGRAM_SIZE; ++PriorityBucketIndex)
{
uint TilesPerBucket = PriorityHistogram[CardUpdateContext * PRIORITY_HISTOGRAM_SIZE + PriorityBucketIndex];
if (UpdateTileSum + TilesPerBucket >= MaxTilesToUpdate)
{
PriorityBucketMaxTiles = MaxTilesToUpdate - UpdateTileSum;
break;
}
UpdateTileSum += TilesPerBucket;
}
RWMaxUpdateBucket[MAX_UPDATE_BUCKET_STRIDE * CardUpdateContext + 0] = PriorityBucketIndex;
RWMaxUpdateBucket[MAX_UPDATE_BUCKET_STRIDE * CardUpdateContext + 1] = PriorityBucketMaxTiles;
}
/**
* Compute max bucket histogram to update and how many tiles should be updated in that last bucket
*/
[numthreads(THREADGROUP_SIZE, 1, 1)]
void SelectMaxUpdateBucketCS(
uint3 GroupId : SV_GroupID,
uint3 GroupThreadId : SV_GroupThreadID,
uint3 DispatchThreadId : SV_DispatchThreadID)
{
if (GroupId.x == 0 && GroupThreadId.x == 0)
{
SelectMaxUpdateBucket(CARD_UPDATE_CONTEXT_DIRECT_LIGHTING);
}
else if (GroupId.x == 1 && GroupThreadId.x == 0)
{
SelectMaxUpdateBucket(CARD_UPDATE_CONTEXT_INDIRECT_LIGHTING);
}
}
4.创建更新列表
BuildCardsUpdateListCS：
card更新列表得到，设置更新数据：再次遍历每个 Card Page，根据最大可更新的 Bucket 将当前 Card Page Index 加入到更新列表中，对应 RDG 资源名为 Lumen.DirectLightingCardPageIndexData 和 Lumen.IndirectLightingCardPageIndexData。同时每个加入到更新列表中的 Card Page 记录当前帧索引，用于下次构建直方图，Pass：Build cards update list。
/**
* Iterate over all cards and pick first N for update based on the histogram max update bucket
*/
[numthreads(THREADGROUP_SIZE, 1, 1)]
void BuildCardsUpdateListCS(
uint3 DispatchThreadId : SV_DispatchThreadID)
{
uint IndexInIndexBuffer = DispatchThreadId.x;
if (IndexInIndexBuffer < CardPageNum)
{
const uint CardPageIndex = IndexInIndexBuffer;
FLumenCardPageData CardPage = GetLumenCardPageData(CardPageIndex);
FLumenCardData Card = GetLumenCardData(CardPage.CardIndex);
const uint NumCardPageTiles = GetNumCardPageTiles(CardPage);
if (NumCardPageTiles > 0)
{
bool bUpdatedCardPage = false;
// On radiosity atlas reset invalidate all history data
if (IndirectLightingHistoryValid == 0)
{
CardPage.LastIndirectLightingUpdateFrameIndex = 0;
bUpdatedCardPage = true;
}
if (BuildCardsUpdateList(
Card,
CardPage,
CardPageIndex,
NumCardPageTiles,
CARD_UPDATE_CONTEXT_DIRECT_LIGHTING,
RWDirectLightingCardPageIndexAllocator,
RWDirectLightingCardPageIndexData))
{
CardPage.LastDirectLightingUpdateFrameIndex = SurfaceCacheUpdateFrameIndex;
bUpdatedCardPage = true;
}
if (BuildCardsUpdateList(
Card,
CardPage,
CardPageIndex,
NumCardPageTiles,
CARD_UPDATE_CONTEXT_INDIRECT_LIGHTING,
RWIndirectLightingCardPageIndexAllocator,
RWIndirectLightingCardPageIndexData))
{
CardPage.LastIndirectLightingUpdateFrameIndex = SurfaceCacheUpdateFrameIndex;
CardPage.IndirectLightingTemporalIndex = CardPage.IndirectLightingTemporalIndex + 1;
bUpdatedCardPage = true;
}
if (bUpdatedCardPage && FreezeUpdateFrame == 0)
{
SetCardPageUpdateData(CardPageIndex, CardPage);
}
}
}
}
BuildCardsUpdateList
bool BuildCardsUpdateList(
FLumenCardData Card,
FLumenCardPageData CardPage,
uint CardPageIndex,
uint NumCardPageTiles,
uint CardUpdateContext,
RWStructuredBuffer<uint> RWCardPageIndexAllocator,
RWStructuredBuffer<uint> RWCardPageIndexData)
{
const uint MaxTilesToUpdate = GetMaxTilesToUpdate(CardUpdateContext);
const uint MaxUpdateBucketIndex = MaxUpdateBucket[MAX_UPDATE_BUCKET_STRIDE * CardUpdateContext + 0];
const uint MaxUpdateBucketMaxTiles = MaxUpdateBucket[MAX_UPDATE_BUCKET_STRIDE * CardUpdateContext + 1];
// Update everything up to the max selected priority bucket
uint PriorityBucketIndex = GetPriorityBucketIndex(Card, CardPage, CardPageIndex, CardUpdateContext);
bool bUpdateThisPage = PriorityBucketIndex <= MaxUpdateBucketIndex;
if (bUpdateThisPage && PriorityBucketIndex == MaxUpdateBucketIndex)
{
// Can't update more than MaxUpdateBucketMaxTiles in the max bucket to preserve the general order
uint NumAllocatedTilesInMaxUpdateBucket = 0;
InterlockedAdd(RWCardPageTileAllocator[CARD_PAGE_TILE_ALLOCATOR_STRIDE * CardUpdateContext + 1], NumCardPageTiles, NumAllocatedTilesInMaxUpdateBucket);
if (!(NumAllocatedTilesInMaxUpdateBucket + NumCardPageTiles <= MaxUpdateBucketMaxTiles))
{
bUpdateThisPage = false;
}
}
if (bUpdateThisPage)
{
bUpdateThisPage = false;
uint NumAllocatedTiles = 0;
InterlockedAdd(RWCardPageTileAllocator[CARD_PAGE_TILE_ALLOCATOR_STRIDE * CardUpdateContext + 0], NumCardPageTiles, NumAllocatedTiles);
if (NumAllocatedTiles + NumCardPageTiles <= MaxTilesToUpdate)
{
uint NextIndex = 0;
InterlockedAdd(RWCardPageIndexAllocator[0], 1, NextIndex);
if (NextIndex < CardPageNum)
{
RWCardPageIndexData[NextIndex] = CardPageIndex;
bUpdateThisPage = true;
}
}
}
return bUpdateThisPage;
}
设置数据：
// Store only card page update data
void SetCardPageUpdateData(uint CardPageId, FLumenCardPageData CardPageData)
{
// Note: layout must match FLumenCardPageData in C++
uint4 Vector4;
Vector4.x = CardPageData.LastDirectLightingUpdateFrameIndex;
Vector4.y = CardPageData.LastIndirectLightingUpdateFrameIndex;
Vector4.z = CardPageData.IndirectLightingTemporalIndex;
Vector4.w = 0;
uint BaseOffset = CardPageId * LUMEN_CARD_PAGE_DATA_STRIDE;
RWLumenCardPageDataBuffer[BaseOffset + 4] = asfloat(Vector4);
}
5.设置命令参数
设置间接参数FSetCardPageIndexIndirectArgsCS：根据上面的数据生成后续步骤的 Indirect Draw 和 Indirect Dispatch 参数
{
FSetCardPageIndexIndirectArgsCS::FParameters* PassParameters = GraphBuilder.AllocParameters<FSetCardPageIndexIndirectArgsCS::FParameters>();
PassParameters->RWDirectLightingDrawCardPageIndicesIndirectArgs = GraphBuilder.CreateUAV(DirectLightingCardUpdateContext.DrawCardPageIndicesIndirectArgs);
PassParameters->RWDirectLightingDispatchCardPageIndicesIndirectArgs = GraphBuilder.CreateUAV(DirectLightingCardUpdateContext.DispatchCardPageIndicesIndirectArgs);
PassParameters->RWIndirectLightingDrawCardPageIndicesIndirectArgs = GraphBuilder.CreateUAV(IndirectLightingCardUpdateContext.DrawCardPageIndicesIndirectArgs);
PassParameters->RWIndirectLightingDispatchCardPageIndicesIndirectArgs = GraphBuilder.CreateUAV(IndirectLightingCardUpdateContext.DispatchCardPageIndicesIndirectArgs);
PassParameters->DirectLightingCardPageIndexAllocator = DirectCardPageIndexAllocatorSRV;
PassParameters->IndirectLightingCardPageIndexAllocator = IndirectCardPageIndexAllocatorSRV;
PassParameters->VertexCountPerInstanceIndirect = GRHISupportsRectTopology ? 3 : 6;
auto ComputeShader = Views[0].ShaderMap->GetShader<FSetCardPageIndexIndirectArgsCS>();
FComputeShaderUtils::AddPass(
GraphBuilder,
RDG_EVENT_NAME("SetCardPageIndexIndirectArgs"),
ComputePassFlags,
ComputeShader,
PassParameters,
FIntVector(1, 1, 1));
}
FSetCardPageIndexIndirectArgsCS
RWBuffer<uint> RWDirectLightingDrawCardPageIndicesIndirectArgs;
RWBuffer<uint> RWDirectLightingDispatchCardPageIndicesIndirectArgs;
RWBuffer<uint> RWIndirectLightingDrawCardPageIndicesIndirectArgs;
RWBuffer<uint> RWIndirectLightingDispatchCardPageIndicesIndirectArgs;
StructuredBuffer<uint> DirectLightingCardPageIndexAllocator;
StructuredBuffer<uint> IndirectLightingCardPageIndexAllocator;
uint VertexCountPerInstanceIndirect;
[numthreads(THREADGROUP_SIZE, 1, 1)]
void SetCardPageIndexIndirectArgsCS(uint3 DispatchThreadId : SV_DispatchThreadID)
{
if (DispatchThreadId.x == 0)
{
{
uint NumPageIndices = DirectLightingCardPageIndexAllocator[0];
// FRHIDrawIndirectParameters
RWDirectLightingDrawCardPageIndicesIndirectArgs[0] = VertexCountPerInstanceIndirect;
RWDirectLightingDrawCardPageIndicesIndirectArgs[1] = NumPageIndices;
RWDirectLightingDrawCardPageIndicesIndirectArgs[2] = 0;
RWDirectLightingDrawCardPageIndicesIndirectArgs[3] = 0;
// Thread per page
WriteDispatchIndirectArgs(RWDirectLightingDispatchCardPageIndicesIndirectArgs, 0, (NumPageIndices + 63) / 64, 1, 1);
// Thread per tile
WriteDispatchIndirectArgs(RWDirectLightingDispatchCardPageIndicesIndirectArgs, 1, 4 * NumPageIndices, 1, 1);
}
{
uint NumPageIndices = IndirectLightingCardPageIndexAllocator[0];
// FRHIDrawIndirectParameters
RWIndirectLightingDrawCardPageIndicesIndirectArgs[0] = VertexCountPerInstanceIndirect;
RWIndirectLightingDrawCardPageIndicesIndirectArgs[1] = NumPageIndices;
RWIndirectLightingDrawCardPageIndicesIndirectArgs[2] = 0;
RWIndirectLightingDrawCardPageIndicesIndirectArgs[3] = 0;
// Thread per page
WriteDispatchIndirectArgs(RWIndirectLightingDispatchCardPageIndicesIndirectArgs, 0, (NumPageIndices + 63) / 64, 1, 1);
// Thread per tile
WriteDispatchIndirectArgs(RWIndirectLightingDispatchCardPageIndicesIndirectArgs, 1, 4 * NumPageIndices, 1, 1);
}
}
}
RenderDirectLightingForLumenScene
void FDeferredShadingSceneRenderer::RenderDirectLightingForLumenScene(FRDGBuilder& GraphBuilder,
const FLumenSceneFrameTemporaries& FrameTemporaries,
const FLumenDirectLightingTaskData* LightingTaskData,
const FLumenCardUpdateContext& CardUpdateContext,
ERDGPassFlags ComputePassFlags)
CullDirectLightingTiles：将cardPage分为tile，以tile为单位对光源进行Culling；每个光源一个light列表
SpliceCardPagesIntoTiles
FBuildLightTilesCS：创建light tile列表
FComputeLightTileOffsetsPerLightCS：计算每个tile的偏移
FInitializeLightTileIndirectArgsCS：为剔除tile初始化间接参数
FCompactLightTilesCS：压缩card tile
ComputeShadowMaskFromLightAttenuation：
FLumenDirectLightingShadowMaskFromLightAttenuationCS 光照函数或普通的
FInitShadowTraceIndirectArgsCS
TraceDistanceFieldShadows
CullMeshObjectsForLightCards
CullDistanceFieldObjectsForLight
ScatterObjectsToShadowTiles
RenderDirectLightIntoLumenCardsBatched：应用光照
CombineLumenSceneLighting：更新最终light
标签：CardPageIndex,CardUpdateContext,CardPage,uint,光照,lumen,const,Card From： https://www.cnblogs.com/Shaojunping/p/18357502