Function DrawEmitterGPU

Source/Engine/Particles/Particles.cpp:1086–1133

}

void DrawEmitterGPU(RenderContextBatch& renderContextBatch, ParticleBuffer* buffer, DrawCall& drawCall, DrawPass drawModes, StaticFlags staticFlags, const BoundingSphere& bounds, uint32 renderModulesIndices, int8 sortOrder)
{
    // Setup drawing data
    uint32 indirectArgsSize = 0;
    ParticleEmitter* emitter = buffer->Emitter;
    for (int32 moduleIndex = 0; moduleIndex < emitter->Graph.RenderModules.Count(); moduleIndex++)
    {
        if ((renderModulesIndices & (1u << moduleIndex)) == 0)
            continue;
        auto module = emitter->Graph.RenderModules.Get()[moduleIndex];
        switch (module->TypeID)
        {
            // Sprite Rendering
        case 400:
            indirectArgsSize += sizeof(GPUDrawIndexedIndirectArgs);
            break;
        // Model Rendering
        case 403:
        {
            const auto model = (Model*)module->Assets[0].Get();
            // TODO: model LOD picking for particles?
            int32 lodIndex = 0;
            ModelLOD& lod = model->LODs[lodIndex];
            indirectArgsSize += sizeof(GPUDrawIndexedIndirectArgs) * lod.Meshes.Count();
            break;
        }
        }
    }
    if (indirectArgsSize == 0)
        return;
    bool sorting = EmitterUseSorting(renderContextBatch, buffer, drawModes, bounds) && (buffer->GPU.ParticlesCountMax != 0 || buffer->GPU.SortedIndices);
    if (sorting && !buffer->GPU.SortedIndices)
        buffer->AllocateSortBuffer();

    // When rendering in async, delay GPU particles drawing to be in sync by moving drawing into delayed callback post scene drawing to use GPUContext safely
    // Also, batch rendering all GPU emitters together for more efficient usage of GPU memory barriers and indirect arguments buffers allocation
    RenderContext::GPULocker.Lock();
    if (GPUEmitterDraws.Count() == 0)
    {
        // The first emitter schedules the drawing of all batched draws
        renderContextBatch.GetMainContext().List->AddDelayedDraw([](GPUContext* context, RenderContextBatch& renderContextBatch, int32 renderContextIndex)
        {
            DrawEmittersGPU(context, renderContextBatch);
        });
    }
    GPUEmitterDraws.Add({ buffer, drawCall, drawModes, staticFlags, bounds, renderModulesIndices, indirectArgsSize, sortOrder, sorting });
    RenderContext::GPULocker.Unlock();
}

#endif