c++ - Direct3D 11缺少GetRasterStatus，如何检测垂直空白期？

我正在更新一个应用程序，其中在屏幕上显示刺激信号的时间需要最大的准确性。目前，它是使用DirectDraw编写的，已经在牧场上放了很久，并且需要更新我们的图形库。

我们测量显示时间的方法是利用检测垂直空白时间的结束。特别是，我需要以最大可能的精度知道屏幕上实际绘制了什么内容(翻转到主表面(或显示在交换链中))。检测扫描线可以增加该测量的确定性，但是我将只能检测在调用Flip或Present之后垂直空白时间何时结束。

Direct 3D 9具有IDirect3DDevice9::GetRasterStatus Method，该IDirectDraw::GetVerticalBlankStatus返回D3DRASTER_STATUS结构，该结构包括InVBlank bool 值，该 bool 值描述设备是否处于垂直空白以及当前扫描行。 DirectDraw具有类似的功能(ojit_a，也可以使用IDirectDraw::GetScanLine在垂直空白期间返回DDERR_VERTICALBLANKINPROGRESS来检测VB)。

但是我无法在Direct3D11中找到任何类似的功能。有谁知道在Direct3D9和Direct3D11之间是否移动或删除了此功能，如果是后者，为什么？

最佳答案

抱歉，回复晚了，但我注意到仍然没有被接受的答案，所以也许您从未找到有效的答案。如今，在Windows上， DesktopWindowManager 服务(dwm.exe)可以协调所有内容，无法真正被绕开。从Windows 8开始，就不能禁用此服务。

因此，DWM始终将控制所有各种IDXGISurface(n)对象和IDXGIOutput(n)监视器的帧速率，渲染队列管理和最终组成，并且除非有必要，否则对于跟踪屏幕外渲染目标的 VSync 跟踪并没有多大用处缺少某些东西(无讽刺意味)。至于您的问题，我不确定您的目标是:

获得极为精确的时序信息，但仅用于诊断，配置文件或信息性使用，或

应用程序是否要(尝试)使用这些结果来计划(尝试)自己的当前周期。

如果是后者，我相信您只有在D3D应用程序以全屏独家模式运行时才能有效地做到这一点。唯一的情况是DWM(以的形式伪装DXGI )将真正信任客户端来处理自己的Present时序。

这里的(很少)好消息是，如果您对 VSync感兴趣仅是引用信息，也就是说，您从上方进入了子弹类别(1.)，那么您确实可以获取所有的计时数据所需，且分辨率为QueryPerformanceFrequency，通常约为320 ns.¹

这是获取高分辨率视频时序信息的方法。但是，再次要说明的是，尽管在如下所示的信息获取中取得了明显的成功，但是任何尝试使用这些有趣的结果(例如，对所获得的读数进行确定性的并因此可能有用的结果)的尝试注定要失败，也就是说，完全被DWM中介挫败了:

typedef struct _DWM_TIMING_INFO
{
    UINT32    cbSize;                 // size of this DWM_TIMING_INFO structure
    URATIO    rateRefresh;            // monitor refresh rate
    QPC_TIME  qpcRefreshPeriod;       // monitor refresh period
    URATIO    rateCompose;            // composition rate
    QPC_TIME  qpcVBlank;              // query performance counter value before the vertical blank
    CFRAMES   cRefresh;               // DWM refresh counter
    UINT      cDXRefresh;             // DirectX refresh counter
    QPC_TIME  qpcCompose;             // query performance counter value for a frame composition
    CFRAMES   cFrame;                 // frame number that was composed at qpcCompose
    UINT      cDXPresent;             // DirectX present number used to identify rendering frames
    CFRAMES   cRefreshFrame;          // refresh count of the frame that was composed at qpcCompose
    CFRAMES   cFrameSubmitted;        // DWM frame number that was last submitted
    UINT      cDXPresentSubmitted;    // DirectX present number that was last submitted
    CFRAMES   cFrameConfirmed;        // DWM frame number that was last confirmed as presented
    UINT      cDXPresentConfirmed;    // DirectX present number that was last confirmed as presented
    CFRAMES   cRefreshConfirmed;      // target refresh count of the last frame confirmed as completed by the GPU
    UINT      cDXRefreshConfirmed;    // DirectX refresh count when the frame was confirmed as presented
    CFRAMES   cFramesLate;            // number of frames the DWM presented late
    UINT      cFramesOutstanding;     // number of composition frames that have been issued but have not been confirmed as completed
    CFRAMES   cFrameDisplayed;        // last frame displayed
    QPC_TIME  qpcFrameDisplayed;      // QPC time of the composition pass when the frame was displayed
    CFRAMES   cRefreshFrameDisplayed; // vertical refresh count when the frame should have become visible
    CFRAMES   cFrameComplete;         // ID of the last frame marked as completed
    QPC_TIME  qpcFrameComplete;       // QPC time when the last frame was marked as completed
    CFRAMES   cFramePending;          // ID of the last frame marked as pending
    QPC_TIME  qpcFramePending;        // QPC time when the last frame was marked as pending
    CFRAMES   cFramesDisplayed;       // number of unique frames displayed
    CFRAMES   cFramesComplete;        // number of new completed frames that have been received
    CFRAMES   cFramesPending;         // number of new frames submitted to DirectX but not yet completed
    CFRAMES   cFramesAvailable;       // number of frames available but not displayed, used, or dropped
    CFRAMES   cFramesDropped;         // number of rendered frames that were never displayed because composition occurred too late
    CFRAMES   cFramesMissed;          // number of times an old frame was composed when a new frame should have been used but was not available
    CFRAMES   cRefreshNextDisplayed;  // frame count at which the next frame is scheduled to be displayed
    CFRAMES   cRefreshNextPresented;  // frame count at which the next DirectX present is scheduled to be displayed
    CFRAMES   cRefreshesDisplayed;    // total number of refreshes that have been displayed for the application since the DwmSetPresentParameters function was last called
    CFRAMES   cRefreshesPresented;    // total number of refreshes that have been presented by the application since DwmSetPresentParameters was last called
    CFRAMES   cRefreshStarted;        // refresh number when content for this window started to be displayed
    ULONGLONG cPixelsReceived;        // total number of pixels DirectX redirected to the DWM
    ULONGLONG cPixelsDrawn;           // number of pixels drawn
    CFRAMES   cBuffersEmpty;          // number of empty buffers in the flip chain
}
DWM_TIMING_INFO;

(注意:要水平压缩以上源代码以在本网站上显示，请假定以下缩写是:)

typedef UNSIGNED_RATIO URATIO;
typedef DWM_FRAME_COUNT CFRAMES;

现在，对于以窗口模式运行的应用程序，您当然可以根据需要随时获取这些详细信息。如果只需要它进行被动配置，那么从DwmGetCompositionTimingInfo获取数据是现代的方法。

谈到现代，既然这个问题暗示要进行现代化，那么您将考虑使用从IDXGISwapChain1获得的IDXGIFactory2::CreateSwapChainForComposition来启用新的DirectComposition组件。



无论如何，详细的时序信息似乎不太可能有用地告知应用程序的运行时行为。 也许它将帮助您预测下一个VSync，但确实想知道“敏锐地了解消隐期”对于某些特定的DWM屏外交换链有何意义。

因为您的应用程序表面只是DWM所处理的众多事情之一，所以DWM将在每个客户端行为一致的假设下自行进行各种动态调整。在这种情况下，不可预测的适应是不合作的，并且可能最终会使双方困惑。

注意: 1. QPC的分辨率比DateTime滴答声的分辨率高很多个数量级，尽管后者建议使用100 ns。单位面额。将DateTime.Now.Ticks视为对(以毫秒为单位)Environment.TickCount的重新打包，但是转换为100 ns单位。为了获得尽可能高的分辨率，请使用静态方法Stopwatch.GetTimestamp()而不是DateTime.Now.Ticks。