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Diffstat (limited to 'src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc')
| -rw-r--r-- | src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc b/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc index 55c8c2c535..57f1495c8e 100644 --- a/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc +++ b/src/quick/doc/src/concepts/visualcanvas/adaptations.qdoc @@ -249,12 +249,29 @@ See the ShaderEffect documentation for more details. \section2 Multisample Render Targets The Direct3D 12 adaptation ignores the QSurfaceFormat set on the QQuickWindow -or QQuickView (or set via QSurfaceFormat::setDefaultFormat()), with one -exception: QSurfaceFormat::samples() is still taken into account. When the -value is greater than 1, multisample offscreen render targets will be created -with the specified sample count and a quality of the maximum supported quality -level. The backend automatically performs resolving into the non-multisample -swapchain buffers after each frame. +or QQuickView (or set via QSurfaceFormat::setDefaultFormat()), with two +exceptions: QSurfaceFormat::samples() and QSurfaceFormat::alphaBufferSize() are +still taken into account. When the samples value is greater than 1, multisample +offscreen render targets will be created with the specified sample count and a +quality of the maximum supported quality level. The backend automatically +performs resolving into the non-multisample swapchain buffers after each frame. + +\section2 Semi-transparent windows + +When the alpha channel is enabled either via +QQuickWindow::setDefaultAlphaBuffer() or by setting alphaBufferSize to a +non-zero value in the window's QSurfaceFormat or in the global format managed +by QSurfaceFormat::setDefaultFormat(), the D3D12 backend will create a +swapchain for composition and go through DirectComposition since the flip model +swapchain (which is mandatory) would not support transparency otherwise. + +It is therefore important not to unneccessarily request an alpha channel. When +the alphaBufferSize is 0 or the default -1, all these extra steps can be +avoided and the traditional window-based swapchain is sufficient. + +This is not relevant on WinRT because there the backend always uses a +composition swapchain which is associated with the ISwapChainPanel that backs +QWindow on that platform. \section2 Mipmaps |