ID3D12GraphicsCommandList::Reset method (d3d12.h)

Article
07/27/2022

Resets a command list back to its initial state as if a new command list was just created.

Syntax

HRESULT Reset(
  [in]           ID3D12CommandAllocator *pAllocator,
  [in, optional] ID3D12PipelineState    *pInitialState
);

Parameters

[in] pAllocator

Type: ID3D12CommandAllocator*

A pointer to the ID3D12CommandAllocator object that the device creates command lists from.

[in, optional] pInitialState

Type: ID3D12PipelineState*

A pointer to the ID3D12PipelineState object that contains the initial pipeline state for the command list. This is optional and can be NULL. If NULL, the runtime sets a dummy initial pipeline state so that drivers don't have to deal with undefined state. The overhead for this is low, particularly for a command list, for which the overall cost of recording the command list likely dwarfs the cost of one initial state setting. So there is little cost in not setting the initial pipeline state parameter if it isn't convenient.

For bundles on the other hand, it might make more sense to try to set the initial state parameter since bundles are likely smaller overall and can be reused frequently.

Return value

Type: HRESULT

Returns S_OK if successful; otherwise, returns one of the following values:

E_FAIL if the command list was not in the "closed" state when the Reset call was made, or the per-device limit would have been exceeded.
E_OUTOFMEMORY if the operating system ran out of memory.
E_INVALIDARG if the allocator is currently being used with another command list in the "recording" state or if the specified allocator was created with the wrong type.

See Direct3D 12 Return Codes for other possible return values.

Remarks

By using Reset, you can re-use command list tracking structures without any allocations. Unlike ID3D12CommandAllocator::Reset, you can call Reset while the command list is still being executed. A typical pattern is to submit a command list and then immediately reset it to reuse the allocated memory for another command list.

You can use Reset for both direct command lists and bundles.

The command allocator that Reset takes as input can be associated with no more than one recording command list at a time. The allocator type, direct command list or bundle, must match the type of command list that is being created.

If a bundle doesn't specify a resource heap, it can't make changes to which descriptor tables are bound. Either way, bundles can't change the resource heap within the bundle. If a heap is specified for a bundle, the heap must match the calling 'parent' command list’s heap.

Runtime validation

Before an app calls Reset, the command list must be in the "closed" state. Reset will fail if the command list isn't in the "closed" state.

Note If a call to ID3D12GraphicsCommandList::Close fails, the command list can never be reset. Calling Reset will result in the same error being returned that ID3D12GraphicsCommandList::Close returned.

After Reset succeeds, the command list is left in the "recording" state. Reset will fail if it would cause the maximum concurrently recording command list limit, which is specified at device creation, to be exceeded.

Apps must specify a command list allocator. The runtime will ensure that an allocator is never associated with more than one recording command list at the same time.

Reset fails for bundles that are referenced by a not yet submitted command list.

Debug layer

The debug layer will also track graphics processing unit (GPU) progress and issue an error if it can't prove that there are no outstanding executions of the command list.

Examples

The D3D12HelloTriangle sample uses ID3D12GraphicsCommandList::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;

void D3D12HelloTriangle::PopulateCommandList()
{
    // 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_commandAllocator->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_commandList->Reset(m_commandAllocator.Get(), m_pipelineState.Get()));

    // Set necessary state.
    m_commandList->SetGraphicsRootSignature(m_rootSignature.Get());
    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->IASetPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST);
    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));

    ThrowIfFailed(m_commandList->Close());
}

See Example Code in the D3D12 Reference.

Requirements

Requirement	Value
Target Platform	Windows
Header	d3d12.h
Library	D3d12.lib
DLL	D3d12.dll