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Optimize particles sorting by splitting key generation and sorting to reduce CS switches

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This commit is contained in:
Wojtek Figat
2025-08-07 19:09:58 +02:00
parent 545df6ce35
commit 3d84380175
1 changed files with 22 additions and 7 deletions
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29
Source/Engine/Particles/Particles.cpp
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@@ -793,13 +793,15 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
if (sorting)
{
PROFILE_GPU_CPU_NAMED("Sort Particles");
// Generate sort keys for each particle
for (const GPUEmitterDraw& draw : GPUEmitterDraws)
{
if (!draw.Sorting)
continue;
ASSERT(draw.Buffer->GPU.SortingKeysBuffer);
// Execute all sorting modules
// Generate sort keys for particles
ParticleEmitter* emitter = draw.Buffer->Emitter;
for (int32 moduleIndex = 0; moduleIndex < emitter->Graph.SortModules.Count(); moduleIndex++)
{
@@ -812,13 +814,11 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
data.ParticleStride = draw.Buffer->Stride;
data.ParticleCapacity = draw.Buffer->Capacity;
int32 permutationIndex;
bool sortAscending;
switch (sortMode)
{
case ParticleSortMode::ViewDepth:
{
permutationIndex = 0;
sortAscending = false;
data.PositionOffset = emitter->Graph.GetPositionAttributeOffset();
const Matrix viewProjection = renderContextBatch.GetMainContext().View.ViewProjection();
if (emitter->SimulationSpace == ParticlesSimulationSpace::Local)
@@ -836,7 +836,6 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
case ParticleSortMode::ViewDistance:
{
permutationIndex = 1;
sortAscending = false;
data.PositionOffset = emitter->Graph.GetPositionAttributeOffset();
data.ViewPosition = renderContextBatch.GetMainContext().View.Position;
if (emitter->SimulationSpace == ParticlesSimulationSpace::Local)
@@ -853,7 +852,6 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
case ParticleSortMode::CustomDescending:
{
permutationIndex = 2;
sortAscending = sortMode == ParticleSortMode::CustomAscending;
int32 attributeIdx = module->Attributes[0];
if (attributeIdx == -1)
break;
@@ -872,9 +870,26 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
context->BindUA(0, draw.Buffer->GPU.SortingKeysBuffer->View());
const int32 threadGroupSize = 1024;
context->Dispatch(GPUParticlesSortingCS[permutationIndex], Math::DivideAndRoundUp(draw.Buffer->GPU.ParticlesCountMax, threadGroupSize), 1, 1);
}
}
// Perform sorting
BitonicSort::Instance()->Sort(context, draw.Buffer->GPU.SortingKeysBuffer, draw.Buffer->GPU.Buffer, data.ParticleCounterOffset, sortAscending, draw.Buffer->GPU.SortedIndices);
// Run sorting
for (const GPUEmitterDraw& draw : GPUEmitterDraws)
{
if (!draw.Sorting)
continue;
ASSERT(draw.Buffer->GPU.SortingKeysBuffer);
// Execute all sorting modules
ParticleEmitter* emitter = draw.Buffer->Emitter;
for (int32 moduleIndex = 0; moduleIndex < emitter->Graph.SortModules.Count(); moduleIndex++)
{
auto module = emitter->Graph.SortModules[moduleIndex];
const auto sortMode = (ParticleSortMode)module->Values[2].AsInt;
bool sortAscending = sortMode == ParticleSortMode::CustomAscending;
BitonicSort::Instance()->Sort(context, draw.Buffer->GPU.SortingKeysBuffer, draw.Buffer->GPU.Buffer, draw.Buffer->GPU.ParticleCounterOffset, sortAscending, draw.Buffer->GPU.SortedIndices);
// TODO: split sorted keys copy with another loop to give time for UAV transition
// TODO: use args buffer from GPUIndirectArgsBuffer instead of internal from BitonicSort to get rid of UAV barrier
}
}
}