@SGaist My solution is heavily inspired by: this old ogre wiki post (should have linked it as well, forgot about it until now). I mostly slimmed it down to what I posted as my solution, but I agree if I have time I'll try to make an example/entry. There are some things that need to be updated from the linked post to fit Ogre 2.1 since the post is old.

I think you have to add a QMultiSampleAntiAliasing to either a QRenderStateSet or a QRenderPassFilter. Did you also enable it in the OpenGL format that you set?

@kenchan I knew that. I want not stacking by z-order, I want simultaneous stacking. It works something like that by default (if opacity of items is 0.5 ) output = Merge(Merge(background, 0.5 × item1), 0.5 × item2) I want something like that output = Merge(background, 0.5 × item1, 0.5 × item2) aka simultaneous merge items to scene, so it not depends from z-order. (example — I want ⅓ background, ⅓ item1 and ⅓ item2, Indifferently to items z-order)

@mrjj No, but I will.

I did register but realized I posted with the wrong email address. Now I've corrected it and can see my post on the list. Thank you.

Thanks for sharing !

Hi, It is a limitation. http://doc.qt.io/qt-5/qopenglwidget.html "Limitations Putting other widgets underneath and making the QOpenGLWidget transparent will not lead to the expected results: The widgets underneath will not be visible. This is because in practice the QOpenGLWidget is drawn before all other regular, non-OpenGL widgets, and so see-through type of solutions are not feasible. Other type of layouts, like having widgets on top of the QOpenGLWidget, will function as expected." You have to use Qt::WA_AlwaysStackOnTop to do this.

Win7 & Qt 5.4.2 with QtCreator 3.4.1

@SGaist Thanks. I'll give it a look.

@Juaruipav Yes it is activated. Did you try by deactivating it ? May be it is a bug on Windows 8.1. Better you should report it on Qt Bug Tracker.

@tmason202 , try this one void QTSemiTransparentWidget::paintEvent(QPaintEvent* event) { QPainter painter(this); painter.setOpacity(0.5); QStyleOption opt; opt.initFrom(this); QStyle* pStyle = QApplication::style(); pStyle->drawPrimitive(QStyle::PE_Widget, &opt, &painter, this); } at least you should draw something in paint event not to just set an opacity.

Yes of course