ID3D12GraphicsCommandList::SetComputeRoot32BitConstants method

void SetComputeRoot32BitConstants(
  [in]       UINT RootParameterIndex,
  [in]       UINT Num32BitValuesToSet,
  [in] const void *pSrcData,
  [in]       UINT DestOffsetIn32BitValues
);

// Fill the command list with all the render commands and dependent state.
void D3D12ExecuteIndirect::PopulateCommandLists()
{
    // Command list allocators can only be reset when the associated 
    // command lists have finished execution on the GPU; apps should use 
    // fences to determine GPU execution progress.
    ThrowIfFailed(m_computeCommandAllocators[m_frameIndex]->Reset());
    ThrowIfFailed(m_commandAllocators[m_frameIndex]->Reset());

    // However, when ExecuteCommandList() is called on a particular command 
    // list, that command list can then be reset at any time and must be before 
    // re-recording.
    ThrowIfFailed(m_computeCommandList->Reset(m_computeCommandAllocators[m_frameIndex].Get(), m_computeState.Get()));
    ThrowIfFailed(m_commandList->Reset(m_commandAllocators[m_frameIndex].Get(), m_pipelineState.Get()));

    // Record the compute commands that will cull triangles and prevent them from being processed by the vertex shader.
    if (m_enableCulling)
    {
        UINT frameDescriptorOffset = m_frameIndex * CbvSrvUavDescriptorCountPerFrame;
        D3D12_GPU_DESCRIPTOR_HANDLE cbvSrvUavHandle = m_cbvSrvUavHeap->GetGPUDescriptorHandleForHeapStart();

        m_computeCommandList->SetComputeRootSignature(m_computeRootSignature.Get());

        ID3D12DescriptorHeap* ppHeaps[] = { m_cbvSrvUavHeap.Get() };
        m_computeCommandList->SetDescriptorHeaps(_countof(ppHeaps), ppHeaps);

        m_computeCommandList->SetComputeRootDescriptorTable(
            SrvUavTable,
            CD3DX12_GPU_DESCRIPTOR_HANDLE(cbvSrvUavHandle, CbvSrvOffset + frameDescriptorOffset, m_cbvSrvUavDescriptorSize));

        m_computeCommandList->SetComputeRoot32BitConstants(RootConstants, 4, reinterpret_cast<void*>(&m_csRootConstants), 0);

        // Reset the UAV counter for this frame.
        m_computeCommandList->CopyBufferRegion(m_processedCommandBuffers[m_frameIndex].Get(), CommandBufferSizePerFrame, m_processedCommandBufferCounterReset.Get(), 0, sizeof(UINT));

        D3D12_RESOURCE_BARRIER barrier = CD3DX12_RESOURCE_BARRIER::Transition(m_processedCommandBuffers[m_frameIndex].Get(), D3D12_RESOURCE_STATE_COPY_DEST, D3D12_RESOURCE_STATE_UNORDERED_ACCESS);
        m_computeCommandList->ResourceBarrier(1, &barrier);

        m_computeCommandList->Dispatch(static_cast<UINT>(ceil(TriangleCount / float(ComputeThreadBlockSize))), 1, 1);
    }

    ThrowIfFailed(m_computeCommandList->Close());

    // Record the rendering commands.
    {
        // Set necessary state.
        m_commandList->SetGraphicsRootSignature(m_rootSignature.Get());

        ID3D12DescriptorHeap* ppHeaps[] = { m_cbvSrvUavHeap.Get() };
        m_commandList->SetDescriptorHeaps(_countof(ppHeaps), ppHeaps);

        m_commandList->RSSetViewports(1, &m_viewport);
        m_commandList->RSSetScissorRects(1, m_enableCulling ? &m_cullingScissorRect : &m_scissorRect);

        // Indicate that the command buffer will be used for indirect drawing
        // and that the back buffer will be used as a render target.
        D3D12_RESOURCE_BARRIER barriers[2] = {
            CD3DX12_RESOURCE_BARRIER::Transition(
                m_enableCulling ? m_processedCommandBuffers[m_frameIndex].Get() : m_commandBuffer.Get(),
                m_enableCulling ? D3D12_RESOURCE_STATE_UNORDERED_ACCESS : D3D12_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE,
                D3D12_RESOURCE_STATE_INDIRECT_ARGUMENT),
            CD3DX12_RESOURCE_BARRIER::Transition(
                m_renderTargets[m_frameIndex].Get(),
                D3D12_RESOURCE_STATE_PRESENT,
                D3D12_RESOURCE_STATE_RENDER_TARGET)
        };

        m_commandList->ResourceBarrier(_countof(barriers), barriers);

        CD3DX12_CPU_DESCRIPTOR_HANDLE rtvHandle(m_rtvHeap->GetCPUDescriptorHandleForHeapStart(), m_frameIndex, m_rtvDescriptorSize);
        CD3DX12_CPU_DESCRIPTOR_HANDLE dsvHandle(m_dsvHeap->GetCPUDescriptorHandleForHeapStart());
        m_commandList->OMSetRenderTargets(1, &rtvHandle, FALSE, &dsvHandle);

        // Record commands.
        const float clearColor[] = { 0.0f, 0.2f, 0.4f, 1.0f };
        m_commandList->ClearRenderTargetView(rtvHandle, clearColor, 0, nullptr);
        m_commandList->ClearDepthStencilView(dsvHandle, D3D12_CLEAR_FLAG_DEPTH, 1.0f, 0, 0, nullptr);

        m_commandList->IASetPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP);
        m_commandList->IASetVertexBuffers(0, 1, &m_vertexBufferView);

        if (m_enableCulling)
        {
            // Draw the triangles that have not been culled.
            m_commandList->ExecuteIndirect(
                m_commandSignature.Get(),
                TriangleCount,
                m_processedCommandBuffers[m_frameIndex].Get(),
                0,
                m_processedCommandBuffers[m_frameIndex].Get(),
                CommandBufferSizePerFrame);
        }
        else
        {
            // Draw all of the triangles.
            m_commandList->ExecuteIndirect(
                m_commandSignature.Get(),
                TriangleCount,
                m_commandBuffer.Get(),
                CommandBufferSizePerFrame * m_frameIndex,
                nullptr,
                0);
        }

        // Indicate that the command buffer may be used by the compute shader
        // and that the back buffer will now be used to present.
        barriers[0].Transition.StateBefore = D3D12_RESOURCE_STATE_INDIRECT_ARGUMENT;
        barriers[0].Transition.StateAfter = m_enableCulling ? D3D12_RESOURCE_STATE_COPY_DEST : D3D12_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE;
        barriers[1].Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
        barriers[1].Transition.StateAfter = D3D12_RESOURCE_STATE_PRESENT;

        m_commandList->ResourceBarrier(_countof(barriers), barriers);

        ThrowIfFailed(m_commandList->Close());
    }
}