ID3D12Device::GetDescriptorHandleIncrementSize method (d3d12.h)

Article
02/22/2024

Gets the size of the handle increment for the given type of descriptor heap. This value is typically used to increment a handle into a descriptor array by the correct amount.

Syntax

UINT GetDescriptorHandleIncrementSize(
  [in] D3D12_DESCRIPTOR_HEAP_TYPE DescriptorHeapType
);

Parameters

[in] DescriptorHeapType

The D3D12_DESCRIPTOR_HEAP_TYPE-typed value that specifies the type of descriptor heap to get the size of the handle increment for.

Return value

Returns the size of the handle increment for the given type of descriptor heap, including any necessary padding.

Remarks

The descriptor size returned by this method is used as one input to the helper structures CD3DX12_CPU_DESCRIPTOR_HANDLE and CD3DX12_GPU_DESCRIPTOR_HANDLE.

Examples

The D3D12PredicationQueries sample uses ID3D12Device::GetDescriptorHandleIncrementSize as follows:

Create the descriptor heap for the resources. The m_rtvDescriptorSize variable stores the render target view descriptor handle increment size, and is used in the Create frame resources section of the code.

// Create descriptor heaps.
{
    // Describe and create a render target view (RTV) descriptor heap.
    D3D12_DESCRIPTOR_HEAP_DESC rtvHeapDesc = {};
    rtvHeapDesc.NumDescriptors = FrameCount;
    rtvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
    rtvHeapDesc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
    ThrowIfFailed(m_device->CreateDescriptorHeap(&rtvHeapDesc, IID_PPV_ARGS(&m_rtvHeap)));

    // Describe and create a depth stencil view (DSV) descriptor heap.
    D3D12_DESCRIPTOR_HEAP_DESC dsvHeapDesc = {};
    dsvHeapDesc.NumDescriptors = 1;
    dsvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_DSV;
    dsvHeapDesc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
    ThrowIfFailed(m_device->CreateDescriptorHeap(&dsvHeapDesc, IID_PPV_ARGS(&m_dsvHeap)));

    // Describe and create a constant buffer view (CBV) descriptor heap.
    D3D12_DESCRIPTOR_HEAP_DESC cbvHeapDesc = {};
    cbvHeapDesc.NumDescriptors = CbvCountPerFrame * FrameCount;
    cbvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV;
    cbvHeapDesc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE;
    ThrowIfFailed(m_device->CreateDescriptorHeap(&cbvHeapDesc, IID_PPV_ARGS(&m_cbvHeap)));

    // Describe and create a heap for occlusion queries.
    D3D12_QUERY_HEAP_DESC queryHeapDesc = {};
    queryHeapDesc.Count = 1;
    queryHeapDesc.Type = D3D12_QUERY_HEAP_TYPE_OCCLUSION;
    ThrowIfFailed(m_device->CreateQueryHeap(&queryHeapDesc, IID_PPV_ARGS(&m_queryHeap)));

    m_rtvDescriptorSize = m_device->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
    m_cbvSrvDescriptorSize = m_device->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV);
}

// Create frame resources.
{
    CD3DX12_CPU_DESCRIPTOR_HANDLE rtvHandle(m_rtvHeap->GetCPUDescriptorHandleForHeapStart());

    // Create a RTV and a command allocator for each frame.
    for (UINT n = 0; n < FrameCount; n++)
    {
        ThrowIfFailed(m_swapChain->GetBuffer(n, IID_PPV_ARGS(&m_renderTargets[n])));
        m_device->CreateRenderTargetView(m_renderTargets[n].Get(), nullptr, rtvHandle);
        rtvHandle.Offset(1, m_rtvDescriptorSize);

        ThrowIfFailed(m_device->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&m_commandAllocators[n])));
    }    
}

Refer to the Example Code in the D3D12 Reference.

Requirements

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

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