Method PrefixSum

Source/Falcor/Utils/Algorithm/PrefixSum.cpp:42–75

} // namespace

PrefixSum::PrefixSum(ref<Device> pDevice) : mpDevice(pDevice)
{
    // Create shaders and state.
    DefineList defines = {{"GROUP_SIZE", std::to_string(kGroupSize)}};
    mpPrefixSumGroupProgram = Program::createCompute(mpDevice, kShaderFile, "groupScan", defines);
    mpPrefixSumGroupVars = ProgramVars::create(mpDevice, mpPrefixSumGroupProgram.get());
    mpPrefixSumFinalizeProgram = Program::createCompute(mpDevice, kShaderFile, "finalizeGroups", defines);
    mpPrefixSumFinalizeVars = ProgramVars::create(mpDevice, mpPrefixSumFinalizeProgram.get());

    mpComputeState = ComputeState::create(mpDevice);

    // Create and bind buffer for per-group sums and total sum.
    mpPrefixGroupSums = mpDevice->createBuffer(
        kGroupSize * sizeof(uint32_t),
        ResourceBindFlags::ShaderResource | ResourceBindFlags::UnorderedAccess,
        MemoryType::DeviceLocal,
        nullptr
    );
    mpTotalSum = mpDevice->createBuffer(sizeof(uint32_t), ResourceBindFlags::UnorderedAccess, MemoryType::DeviceLocal, nullptr);
    mpPrevTotalSum = mpDevice->createBuffer(sizeof(uint32_t), ResourceBindFlags::ShaderResource, MemoryType::DeviceLocal, nullptr);

    {
        auto var = mpPrefixSumGroupVars->getRootVar();
        var["gPrefixGroupSums"] = mpPrefixGroupSums;
        var["gTotalSum"] = mpTotalSum;
        var["gPrevTotalSum"] = mpPrevTotalSum;
    }
    {
        auto var = mpPrefixSumFinalizeVars->getRootVar();
        var["gPrefixGroupSums"] = mpPrefixGroupSums;
        var["gTotalSum"] = mpTotalSum;
        var["gPrevTotalSum"] = mpPrevTotalSum;
    }
}

void PrefixSum::execute(
    RenderContext* pRenderContext,