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Optimize GPU particles simulation, sorting and drawing with better resource transition barriers

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This commit is contained in:
Wojtek Figat
2025-08-09 23:59:52 +02:00
parent 82231981dc
commit ff3d785483
1 changed files with 68 additions and 4 deletions
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72
Source/Engine/Particles/Particles.cpp
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@@ -12,6 +12,7 @@
#include "Engine/Graphics/RenderTask.h"
#include "Engine/Graphics/DynamicBuffer.h"
#include "Engine/Graphics/GPUContext.h"
#include "Engine/Graphics/GPUPass.h"
#include "Engine/Graphics/RenderTools.h"
#include "Engine/Graphics/Shaders/GPUVertexLayout.h"
#include "Engine/Profiler/ProfilerCPU.h"
@@ -748,6 +749,11 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
{
PROFILE_GPU_CPU_NAMED("Init Indirect Args");
GPUMemoryPass pass(context);
pass.Transition(GPUIndirectArgsBuffer, GPUResourceAccess::CopyWrite);
for (GPUEmitterDraw& draw : GPUEmitterDraws)
pass.Transition(draw.Buffer->GPU.Buffer, GPUResourceAccess::CopyRead);
// Init default arguments
byte* indirectArgsMemory = (byte*)renderContextBatch.GetMainContext().List->Memory.Allocate(indirectArgsSize, GPU_SHADER_DATA_ALIGNMENT);
for (GPUEmitterDraw& draw : GPUEmitterDraws)
@@ -872,6 +878,18 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
// Generate sort keys for each particle
{
PROFILE_GPU("Gen Sort Keys");
GPUComputePass pass(context);
for (const GPUEmitterDraw& draw : GPUEmitterDraws)
{
if (draw.Sorting)
{
pass.Transition(draw.Buffer->GPU.Buffer, GPUResourceAccess::ShaderReadCompute);
pass.Transition(draw.Buffer->GPU.SortedIndices, GPUResourceAccess::UnorderedAccess);
pass.Transition(draw.Buffer->GPU.SortingKeys, GPUResourceAccess::UnorderedAccess);
}
}
for (const GPUEmitterDraw& draw : GPUEmitterDraws)
{
if (!draw.Sorting)
@@ -935,12 +953,29 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
}
// Run sorting
constexpr int32 inplaceSortSizeLimit = 2048;
{
// Small emitters can be sorted in-place with a single independent dispatch (simultaneously)
GPUComputePass pass(context);
for (const GPUEmitterDraw& draw : GPUEmitterDraws)
{
if (!draw.Sorting || draw.Buffer->GPU.ParticlesCountMax > inplaceSortSizeLimit)
continue;
ParticleEmitter* emitter = draw.Buffer->Emitter;
for (int32 moduleIndex = 0; moduleIndex < emitter->Graph.SortModules.Count(); moduleIndex++)
{
auto module = emitter->Graph.SortModules[moduleIndex];
// TODO: add support for module->SortedIndicesOffset (multiple sort modules)
const auto sortMode = (ParticleSortMode)module->Values[2].AsInt;
bool sortAscending = sortMode == ParticleSortMode::CustomAscending;
BitonicSort::Instance()->Sort(context, draw.Buffer->GPU.SortedIndices, draw.Buffer->GPU.SortingKeys, draw.Buffer->GPU.Buffer, draw.Buffer->GPU.ParticleCounterOffset, sortAscending, draw.Buffer->GPU.ParticlesCountMax);
}
}
}
for (const GPUEmitterDraw& draw : GPUEmitterDraws)
{
if (!draw.Sorting)
if (!draw.Sorting || draw.Buffer->GPU.ParticlesCountMax <= inplaceSortSizeLimit)
continue;
// Execute all sorting modules
ParticleEmitter* emitter = draw.Buffer->Emitter;
for (int32 moduleIndex = 0; moduleIndex < emitter->Graph.SortModules.Count(); moduleIndex++)
{
@@ -950,11 +985,12 @@ void DrawEmittersGPU(RenderContextBatch& renderContextBatch)
bool sortAscending = sortMode == ParticleSortMode::CustomAscending;
BitonicSort::Instance()->Sort(context, draw.Buffer->GPU.SortedIndices, draw.Buffer->GPU.SortingKeys, draw.Buffer->GPU.Buffer, draw.Buffer->GPU.ParticleCounterOffset, sortAscending, draw.Buffer->GPU.ParticlesCountMax);
// TODO: use args buffer from GPUIndirectArgsBuffer instead of internal from BitonicSort to get rid of UAV barrier (all sorting in parallel)
// TODO: run small emitters sorting (less than 2k particles) sorting in separate loop as pass without UAV barriers (all sorting in parallel)
}
}
}
// TODO: transition here SortedIndices into ShaderReadNonPixel and Buffer into ShaderReadGraphics to reduce barriers during particles rendering
// Submit draw calls
for (GPUEmitterDraw& draw : GPUEmitterDraws)
{
@@ -1326,6 +1362,15 @@ void UpdateGPU(RenderTask* task, GPUContext* context)
// Pre-pass with buffers setup
{
PROFILE_CPU_NAMED("PreSim");
GPUMemoryPass pass(context);
for (GPUSim& sim : sims)
{
if (sim.Data.Buffer->GPU.PendingClear)
pass.Transition(sim.Data.Buffer->GPU.Buffer, GPUResourceAccess::CopyWrite);
pass.Transition(sim.Data.Buffer->GPU.BufferSecondary, GPUResourceAccess::CopyWrite);
}
for (GPUSim& sim : sims)
{
sim.Emitter->GPU.PreSim(context, sim.Emitter, sim.Effect, sim.EmitterIndex, sim.Data);
@@ -1335,6 +1380,14 @@ void UpdateGPU(RenderTask* task, GPUContext* context)
// Pre-pass with buffers setup
{
PROFILE_GPU_CPU_NAMED("Sim");
GPUComputePass pass(context);
for (GPUSim& sim : sims)
{
pass.Transition(sim.Data.Buffer->GPU.Buffer, GPUResourceAccess::ShaderReadCompute);
pass.Transition(sim.Data.Buffer->GPU.BufferSecondary, GPUResourceAccess::UnorderedAccess);
}
for (GPUSim& sim : sims)
{
sim.Emitter->GPU.Sim(context, sim.Emitter, sim.Effect, sim.EmitterIndex, sim.Data);
@@ -1344,6 +1397,17 @@ void UpdateGPU(RenderTask* task, GPUContext* context)
// Post-pass with buffers setup
{
PROFILE_CPU_NAMED("PostSim");
GPUMemoryPass pass(context);
for (GPUSim& sim : sims)
{
if (sim.Data.CustomData.HasItems())
{
pass.Transition(sim.Data.Buffer->GPU.BufferSecondary, GPUResourceAccess::CopyRead);
pass.Transition(sim.Data.Buffer->GPU.Buffer, GPUResourceAccess::CopyWrite);
}
}
for (GPUSim& sim : sims)
{
sim.Emitter->GPU.PostSim(context, sim.Emitter, sim.Effect, sim.EmitterIndex, sim.Data);