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D3D11Rhi: change default swap effect to FLIP_DISCARD

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The original comments are misreading Microsoft documents. It seems
Microsoft uses FLIP_SEQUENTIAL to refer to the flip model, not just
FLIP_SEQUENTIAL itself. And according to my experiments, DXGI_SCALING_NONE
can be used with FLIP_DISCARD indeed. The swap chain can be created
successfully and I didn't get any failed HRESULTs. So there's no need
to use FLIP_SEQUENTIAL as the default swap effect anymore. Let's change
it back to FLIP_DISCARD.

Change-Id: I6001e2070d3ff00268299e81f6a310394e62c464
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
This commit is contained in:
Yuhang Zhao 2022-11-01 16:51:06 +08:00
parent 3a8980304f
commit 17b542c2d2
2 changed files with 5 additions and 20 deletions
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22
src/gui/rhi/qrhid3d11.cpp
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@ -173,8 +173,8 @@ bool QRhiD3D11::create(QRhi::Flags flags)
factory5->Release(); factory5->Release();
} }
// if we default to FLIP_SEQUENTIAL, have a way to request FLIP_DISCARD if (qEnvironmentVariableIntValue("QT_D3D_FLIP_DISCARD"))
forceFlipDiscard = qEnvironmentVariableIntValue("QT_D3D_FLIP_DISCARD"); qWarning("The default swap effect is FLIP_DISCARD, QT_D3D_FLIP_DISCARD is now ignored");
if (qEnvironmentVariableIntValue("QT_D3D_NO_FLIP")) if (qEnvironmentVariableIntValue("QT_D3D_NO_FLIP"))
qWarning("Non-FLIP swapchains are no longer supported, QT_D3D_NO_FLIP is now ignored"); qWarning("Non-FLIP swapchains are no longer supported, QT_D3D_NO_FLIP is now ignored");
@ -182,8 +182,7 @@ bool QRhiD3D11::create(QRhi::Flags flags)
qCDebug(QRHI_LOG_INFO, "FLIP_* swapchain supported = true, ALLOW_TEARING supported = %s", qCDebug(QRHI_LOG_INFO, "FLIP_* swapchain supported = true, ALLOW_TEARING supported = %s",
supportsAllowTearing ? "true" : "false"); supportsAllowTearing ? "true" : "false");
qCDebug(QRHI_LOG_INFO, "Default swap effect: %s", qCDebug(QRHI_LOG_INFO, "Default swap effect: FLIP_DISCARD");
forceFlipDiscard ? "FLIP_DISCARD" : "FLIP_SEQUENTIAL");
if (!importedDeviceAndContext) { if (!importedDeviceAndContext) {
IDXGIAdapter1 *adapter; IDXGIAdapter1 *adapter;
@ -4873,21 +4872,8 @@ bool QD3D11SwapChain::createOrResize()
desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
desc.BufferCount = BUFFER_COUNT; desc.BufferCount = BUFFER_COUNT;
desc.Flags = swapChainFlags; desc.Flags = swapChainFlags;
// Normally we'd want FLIP_DISCARD, but that comes with the default
// SCALING_STRETCH, as SCALING_NONE is documented to be only
// available for FLIP_SEQUENTIAL. The problem with stretch is that
// Qt Quick and similar apps typically running in resizable windows
// will not like how that looks in practice: the content will
// appear to be "jumping" around during a window resize. So choose
// sequential/none by default.
if (rhiD->forceFlipDiscard) {
desc.Scaling = DXGI_SCALING_STRETCH;
desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
} else {
desc.Scaling = DXGI_SCALING_NONE; desc.Scaling = DXGI_SCALING_NONE;
desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL; desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
}
if (dcompVisual) { if (dcompVisual) {
// With DirectComposition setting AlphaMode to STRAIGHT fails the // With DirectComposition setting AlphaMode to STRAIGHT fails the

1
src/gui/rhi/qrhid3d11_p_p.h
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@ -737,7 +737,6 @@ public:
IDXGIFactory1 *dxgiFactory = nullptr; IDXGIFactory1 *dxgiFactory = nullptr;
IDCompositionDevice *dcompDevice = nullptr; IDCompositionDevice *dcompDevice = nullptr;
bool supportsAllowTearing = false; bool supportsAllowTearing = false;
bool forceFlipDiscard = false;
bool deviceLost = false; bool deviceLost = false;
QRhiD3D11NativeHandles nativeHandlesStruct; QRhiD3D11NativeHandles nativeHandlesStruct;
QRhiDriverInfo driverInfoStruct; QRhiDriverInfo driverInfoStruct;