how to provide multiple render threads for scene graph for more than one QQuickWindow instances on-screen ?

[mohammad sina msh]

i wanted to have more than on qquickwindow with scene graph and according to this link : https://doc.qt.io/qt-6/qtquick-visualcanvas-scenegraph.html#what-if-there-is-no-or-more-than-one-window-visible

i think i should prepare multiple render threads for handle this..
how can i prepare multiple render thread for multiple qquickwindow with scenegraph?

[jeremy_k]

According to the source code in Qt 5.15.2 and 6.6.1, the threaded scene graph renderer automatically allocates 1 thread per window. There's no additional configuration necessary.

[mohammad sina msh]

@jeremy_k hi and thanks for your comment.
but when i use a qquickwindow every thing goes well and i set graphics api in that window in main.cpp with this code :

 QQuickWindow::setGraphicsApi(QSGRendererInterface::OpenGL);

and when i remove this code from main c++ it couldnt render any more.

so i think my problem is related to this setGraphicsApi

because in my problem when i open another qquickwindow inside the main window on qml with a scence graph,
the new window and the main window couldnt render well
and text that loaded with opengl could'nt render well and rectangle that i draw render with a single color green color.
and its not any more like that thing that i drawed.
i cant show you by 2 screenshot from my app first is when i open my app by just one window and second is my app when i opened second window scenegraph:

you can see texts are ok and render rectangles and lines is ok.
but in second screen shout every thing are not ok:

some time main window render well some time not well .and second window every time couldn't render .
and this second window should render just like main window

[mohammad sina msh]

@jeremy_k
and this is screenshot of when mainwindow and second window all of that couln't render well:

[mohammad sina msh]

@jeremy_k hello could you help me?

[jeremy_k]

That looks like a graphics driver/interface usage problem rather than a lack of rendering threads. The software renderer might be a viable option. An upgrade or downgrade of Qt or the driver might fix it.