How (if) can i render a stack of scenes one on the other? Having multiple viewports covering entire screen turns out does not do this at all. I think clearing z buffer is needed after each scene is rendered too.
Has been discussed a few times on the forum already. Indeed, use another viewport, and a customized renderpath that only clears depth but not color.
One such thread with code: topic1749.html
Ah, here’s the one I remember:
How to Layer Scenes
did just that