Method Sim

Source/Engine/Particles/Graph/GPU/GPUParticles.cpp:169–277

}

void GPUParticles::Sim(GPUContext* context, ParticleEmitter* emitter, ParticleEffect* effect, int32 emitterIndex, ParticleEmitterInstance& data)
{
    PROFILE_CPU_ASSET(emitter);
    const bool hasCB = _cbData.HasItems();
    const int32 threads = data.Buffer->GPU.ParticlesCountMax + data.GPU.SpawnCount;
    const uint32 counterOffset = data.Buffer->GPU.ParticleCounterOffset;
    SceneRenderTask* viewTask = effect->GetRenderTask();

    // Setup parameters
    MaterialParameter::BindMeta bindMeta;
    bindMeta.Context = context;
    bindMeta.Constants = hasCB ? ToSpan(_cbData).Slice(sizeof(GPUParticlesData)) : Span<byte>(nullptr, 0);
    bindMeta.Input = nullptr;
    if (viewTask)
    {
        bindMeta.Buffers = viewTask->Buffers;
        bindMeta.CanSampleDepth = bindMeta.CanSampleGBuffer = bindMeta.Buffers && bindMeta.Buffers->GetWidth() != 0;
    }
    else
    {
        bindMeta.Buffers = nullptr;
        bindMeta.CanSampleDepth = bindMeta.CanSampleGBuffer = false;
    }
    ASSERT(data.Parameters.Count() <= _params.Count());
    for (int32 i = 0; i < data.Parameters.Count(); i++)
    {
        // Copy instance parameters values
        _params[i].SetValue(data.Parameters.Get()[i]);
    }
    MaterialParamsLink link;
    link.This = &_params;
    link.Up = link.Down = nullptr;
    MaterialParams::Bind(&link, bindMeta);

    // Setup constant buffer
    if (hasCB)
    {
        auto cbData = (GPUParticlesData*)_cbData.Get();
        if (viewTask)
        {
            auto& view = viewTask->View;

            Matrix::Transpose(view.PrevViewProjection, cbData->ViewProjectionMatrix);

            Matrix tmp;
            Matrix::Invert(view.PrevViewProjection, tmp);
            Matrix::Transpose(tmp, cbData->InvViewProjectionMatrix);

            Matrix::Invert(view.PrevView, tmp);
            Matrix::Transpose(tmp, cbData->InvViewMatrix);

            Matrix::Transpose(view.PrevView, cbData->ViewMatrix);

            cbData->ViewPos = view.Position;
            cbData->ViewFar = view.Far;
            cbData->ViewDir = view.Direction;
            cbData->ViewInfo = view.ViewInfo;
            cbData->ScreenSize = view.ScreenSize;