I worked on the PR @yaustar listed to get this working as an engine example, and even though that works, I don’t like the need to create 6 layers, 6 cameras, and especially having to add all objects to those layers. This is even worse for multiple cameras.
And so I’m exploring the option to modify engine’s layer system to allow render target to be specified on the camera instead of the layer. The new cubemap / texture rendering based on this, that I have working locally, is a lot simpler now, but this is not part of PR as that needs few more things to be finished, and it would need a lot of testing as it might break compatibility for some projects. But the hope is that in the not too far future this will get easy to do.