ID3D12CommandAllocator::Reset method (d3d12.h)

Indicates to re-use the memory that is associated with the command allocator.


HRESULT Reset();

Return value


This method returns E_FAIL if there is an actively recording command list referencing the command allocator. The debug layer will also issue an error in this case.
See Direct3D 12 Return Codes for other possible return values.


Your app calls Reset to re-use the memory that is associated with a command allocator. From this call to Reset, the runtime and driver assume that the graphics processing unit (GPU) is no longer executing any command lists that have recorded commands with the command allocator. So you should ensure that you don't call Reset until the GPU is done executing command lists associated with the allocator.

It's undefined behavior to call Reset on a command allocator while it has a command list still being executed.

The debug layer will issue a warning if it can't prove that there are no pending GPU references to command lists that have recorded commands in the allocator.

The debug layer will issue an error if Reset is called concurrently by multiple threads (on the same allocator object).


The D3D12HelloTriangle sample uses ID3D12CommandAllocator::Reset as follows:

D3D12_VIEWPORT m_viewport;
D3D12_RECT m_scissorRect;
ComPtr<IDXGISwapChain3> m_swapChain;
ComPtr<ID3D12Device> m_device;
ComPtr<ID3D12Resource> m_renderTargets[FrameCount];
ComPtr<ID3D12CommandAllocator> m_commandAllocator;
ComPtr<ID3D12CommandQueue> m_commandQueue;
ComPtr<ID3D12RootSignature> m_rootSignature;
ComPtr<ID3D12DescriptorHeap> m_rtvHeap;
ComPtr<ID3D12PipelineState> m_pipelineState;
ComPtr<ID3D12GraphicsCommandList> m_commandList;
UINT m_rtvDescriptorSize;
// 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.

// 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_commandList->Reset(m_commandAllocator.Get(), m_pipelineState.Get()));

// Set necessary state.
m_commandList->RSSetViewports(1, &m_viewport);
m_commandList->RSSetScissorRects(1, &m_scissorRect);

// Indicate that the back buffer will be used as a render target.
m_commandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(m_renderTargets[m_frameIndex].Get(), D3D12_RESOURCE_STATE_PRESENT, D3D12_RESOURCE_STATE_RENDER_TARGET));

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

// Record commands.
const float clearColor[] = { 0.0f, 0.2f, 0.4f, 1.0f };
m_commandList->ClearRenderTargetView(rtvHandle, clearColor, 0, nullptr);
m_commandList->IASetVertexBuffers(0, 1, &m_vertexBufferView);
m_commandList->DrawInstanced(3, 1, 0, 0);

// Indicate that the back buffer will now be used to present.
m_commandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(m_renderTargets[m_frameIndex].Get(), D3D12_RESOURCE_STATE_RENDER_TARGET, D3D12_RESOURCE_STATE_PRESENT));


Refer to the Example Code in the D3D12 Reference.


Requirement Value
Target Platform Windows
Header d3d12.h
Library D3D12.lib
DLL D3D12.dll

See also