ID3D12GraphicsCommandList::Dispatch method (d3d12.h)

Executes a command list from a thread group.

Syntax

void Dispatch(
  [in] UINT ThreadGroupCountX,
  [in] UINT ThreadGroupCountY,
  [in] UINT ThreadGroupCountZ
);

Parameters

[in] ThreadGroupCountX

Type: UINT

The number of groups dispatched in the x direction. ThreadGroupCountX must be less than or equal to D3D11_CS_DISPATCH_MAX_THREAD_GROUPS_PER_DIMENSION (65535).

[in] ThreadGroupCountY

Type: UINT

The number of groups dispatched in the y direction. ThreadGroupCountY must be less than or equal to D3D11_CS_DISPATCH_MAX_THREAD_GROUPS_PER_DIMENSION (65535).

[in] ThreadGroupCountZ

Type: UINT

The number of groups dispatched in the z direction. ThreadGroupCountZ must be less than or equal to D3D11_CS_DISPATCH_MAX_THREAD_GROUPS_PER_DIMENSION (65535). In feature level 10 the value for ThreadGroupCountZ must be 1.

Return value

None

Remarks

You call the Dispatch method to execute commands in a compute shader. A compute shader can be run on many threads in parallel, within a thread group. Index a particular thread, within a thread group using a 3D vector given by (x,y,z).

Examples

The D3D12nBodyGravity sample uses ID3D12GraphicsCommandList::Dispatch as follows:

// Run the particle simulation using the compute shader.
void D3D12nBodyGravity::Simulate(UINT threadIndex)
{
    ID3D12GraphicsCommandList* pCommandList = m_computeCommandList[threadIndex].Get();

    UINT srvIndex;
    UINT uavIndex;
    ID3D12Resource *pUavResource;
    if (m_srvIndex[threadIndex] == 0)
    {
        srvIndex = SrvParticlePosVelo0;
        uavIndex = UavParticlePosVelo1;
        pUavResource = m_particleBuffer1[threadIndex].Get();
    }
    else
    {
        srvIndex = SrvParticlePosVelo1;
        uavIndex = UavParticlePosVelo0;
        pUavResource = m_particleBuffer0[threadIndex].Get();
    }

    pCommandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(pUavResource, D3D12_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE, D3D12_RESOURCE_STATE_UNORDERED_ACCESS));

    pCommandList->SetPipelineState(m_computeState.Get());
    pCommandList->SetComputeRootSignature(m_computeRootSignature.Get());

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

    CD3DX12_GPU_DESCRIPTOR_HANDLE srvHandle(m_srvUavHeap->GetGPUDescriptorHandleForHeapStart(), srvIndex + threadIndex, m_srvUavDescriptorSize);
    CD3DX12_GPU_DESCRIPTOR_HANDLE uavHandle(m_srvUavHeap->GetGPUDescriptorHandleForHeapStart(), uavIndex + threadIndex, m_srvUavDescriptorSize);

    pCommandList->SetComputeRootConstantBufferView(RootParameterCB, m_constantBufferCS->GetGPUVirtualAddress());
    pCommandList->SetComputeRootDescriptorTable(RootParameterSRV, srvHandle);
    pCommandList->SetComputeRootDescriptorTable(RootParameterUAV, uavHandle);

    pCommandList->Dispatch(static_cast<int>(ceil(ParticleCount / 128.0f)), 1, 1);

    pCommandList->ResourceBarrier(1, &CD3DX12_RESOURCE_BARRIER::Transition(pUavResource, D3D12_RESOURCE_STATE_UNORDERED_ACCESS, D3D12_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE));
}

See Example Code in the D3D12 Reference.

Requirements

See also

ID3D12GraphicsCommandList