DirectX 12 GetCurrentBackBufferIndex Does Not Return 0 or 1

Thank you for your help.I created a swap chain on DirectX 12.
Since then, I have encountered the GetCurrentBackBufferIndex not returning 0 or 1.

The operating system used is Windows 10 64bit
The compiler is visual studio 2019

The code is as follows:

Create a

 window and create a hwnd
void Window::CreateGameWindow (WNDCLASSEX&windowClass)
{
    auto result=CoInitializeEx(nullptr,COINIT_MULTITHREADED);

    m_windowClass.hInstance=GetModuleHandle(nullptr);
    m_windowClass.cbSize=sizeof(WNDCLASSEX);
    m_windowClass.lpfnWndProc=(WNDPROC) Windowprocedure;
    m_windowClass.lpszClassName="DirectX12 Sample";
    RegisterClassEx(&m_windowClass);

    RECT wrc={};
    wrc.left = 0;
    wrc.top = 0;
    wrc.right = window_width;
    wrc.bottom=window_height;
    AdjustWindowRect (&wrc, WS_OVERLAPPEDWINDOW, false);


    m_hwnd = CreateWindow(
        m_windowClass.lpszClassName,
        "DirectX12",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        wrc.right-wrc.left,
        wrc.bottom-wrc.top,
        nullptr,
        nullptr,
        m_windowClass.hInstance,
        nullptr
    );

     ShowWindow(m_hwnd,SW_SHOW); // Window Display
}

Generate swap chains
DXGI_SWAP_CHAIN_DESC1swapchainDesc={};
   swapchainDesc.Width=window.window_width;
   swapchainDesc.Height=window.window_height;
   swapchainDesc.Format=DXGI_FORMAT_R8G8B8A8_UNORM;
   swapchainDesc.Stereo=false;
   swapchainDesc.SampleDesc.Count=1;
   swapchainDesc.SampleDesc.Quality=0;
   swapchainDesc.BufferUsage=DXGI_USAGE_BACK_BUFFER;
   swapchainDesc.BufferCount=2;
   swapchainDesc.Scaling=DXGI_SCALING_STRETCH;
   swapchainDesc.SwapEffect=DXGI_SWAP_EFFECT_FLIP_DISCARD;
   swapchainDesc.AlphaMode=DXGI_ALPHA_MODE_UNSPECIFIED;
   swapchainDesc.Flags=DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH;


   auto result=m_dxgifactory->CreateSwapChainForHwnd(
       m_cqueue.Get(),
       hwnd,
       &swapchainDesc,
       nullptr,
       nullptr,
       (IDXGISwapChain1**) (m_swapchain.ReleaseAndGetAddressOf())
   );

//Tick processing. call backbuffer index
        autoBbufferIndex=m_swapchain->GetCurrentBackBufferIndex();

Swapchain generation seems to have failed, but it returned S_OK at generation, and there may be other factors.

I would appreciate it if you could let me know if there are any factors that make the swap chain apparently successful.

c++

2022-09-30 15:37

1 Answers

Do you mean GetCurrentBackBufferIndex is IDXGISwapChain3::GetCurrentBackBufferIndex? If that's the case,

auto result=m_dxgifactory->CreateSwapChainForHwnd(
      m_cqueue.Get(),
      hwnd,
      &swapchainDesc,
      nullptr,
      nullptr,
      (IDXGISwapChain1**) (m_swapchain.ReleaseAndGetAddressOf())
  );

I'm concerned that I'm forcing a C-format cast here.

ComPtr<IDXGISwapChain1>swapchain1;
    auto result=m_dxgifactory->CreateSwapChainForHwnd(
        m_cqueue.Get(),
        hwnd,
        &swapchainDesc,
        nullptr,
        nullptr,
        &swapChain1
    );
    result=swapchain1.As(&m_swapchain);

How about casting with IUnknown::QueryInterface sometimes?

2022-09-30 15:37

If you have any answers or tips

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