Direct3D 12 窗口模式强制 vsync

Question

我正在编写一个简单的 Direct3D 12 应用程序来为 Vulkan 的发布做准备，它在所有方面都按预期工作，但有一个：运行在有边框的 window 中将帧速率限制为 60fps ，即使禁用了 vsync。让我困惑的是：同一个程序在全屏模式下 window 以接近 4000fps 的速度运行。

使用肮脏的自制分析器，我发现挂起发生在我的代码的这一部分，它一直等到最后一帧完成才开始处理下一帧。

if (m_fence->GetCompletedValue() < endFenceValue)
{
    result = m_fence->SetEventOnCompletion(endFenceValue, m_fenceEvent);
    if (result != S_OK) return false;
    WaitForSingleObject(m_fenceEvent, INFINITE); //Program stalls here
}
//m_fence is a pointer to an ID3D12Fence object
//endFenceValue is an unsigned long long
//m_fenceEvent is a HANDLE

用于呈现渲染帧的代码很普通：

if (m_vsync)
{
    result = m_swapChain->Present(1, 0);
    if (result != S_OK) return 0;
}
else
{
    result = m_swapChain->Present(0, 0);
    if (result != S_OK) return 0;
}

//Increase the fence value
result = m_commandQueue->Signal(m_fence, m_fenceValue);
if (result != S_OK) return 0;

return m_fenceValue++;
//m_swapChain is a pointer to an IDXGISwapChain3 object
//m_commandQueue is a pointer to an ID3D12CommandQueue object
//m_fenceValue is a HANDLE

注意：第一个代码块使用上述函数的 return 值作为 endFenceValue。

我使用的交换链是这样设置的：

swapChainDesc.BufferCount = 2; //Double buffered
swapChainDesc.BufferDesc.Width = width; //Set width
swapChainDesc.BufferDesc.Height = height; //Set height
swapChainDesc.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; //32-bit back buffers
swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; //Set the back buffers to be used as render targets
swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD; //Throw out old back buffer contents after getting a new frame
swapChainDesc.OutputWindow = window;
swapChainDesc.Windowed = !fullscreen;
//Auto-detect the refresh rate
swapChainDesc.BufferDesc.RefreshRate.Numerator = 0;
swapChainDesc.BufferDesc.RefreshRate.Denominator = 0;

//No multisampling for now
swapChainDesc.SampleDesc.Count = 1;
swapChainDesc.SampleDesc.Quality = 0;
//Set the scan line ordering and scaling to unspecified
swapChainDesc.BufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;
swapChainDesc.BufferDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;
//Allow to switch between windowed and fullscreen modes
//Also changes the monitor resolution to match the width and height of the window in fullscreen mode
swapChainDesc.Flags = DXGI_SWAP_CHAIN_FLAG_ALLOW_MODE_SWITCH;

对于那些感兴趣的人，我正在使用 SDL 创建 window，但是我自己编写 WinMain 并没有解决问题。我还尝试在 nVidia 控制面板中检查我的 vsync 设置，退出 fl.ux（但不卸载它），并在系统属性中更改我的性能设置。

任何人都可以为此提供解释或解决方案吗？

Answer 1

根据 nVidia Developer Zone，这实际上是预期的行为。目前，获得无上限帧率的唯一方法是全屏 window.

Answer 2

windows10 构建版本 10586 中删除了窗口交换链的刷新率上限。

更新您的 windows 它应该会自行解决。

Direct3D 12 窗口模式强制 vsync

Direct3D 12 windowed mode forces vsync

c++

directx

direct3d

vsync

directx-12