When running a Qt Quick application with QSG_RHI=1 QSG_RHI_BACKEND=gl we get rendering via OpenGL, but it will go through QRhi.
Even if Quick 3D is rendering directly via OpenGL, it should still be functional in this setup.
Currently this is not the case since the rhi path of Quick needs a slightly different approach for connecting to the overlay/underlay signals like QQuickWindow::beforeRendering(). Also createTextureFromId() is not something that should be called.
Figure out how to make it work regardless of using or not using the rhi-based rendering path.
- is required for
QTBUG-78614 Prove that integrating bigger external graphics frameworks is feasible in Qt Quick on QRhi on OpenGL