The question is a bit confusing, but here is a better explanation:
I’m trying to build a level that goes from exterior to interior… So the beginning of the corridor needs to exist from both the inside and the outside, let’s say:
But then we don’t need all the extra fluff, so an interior corridor that you can only see from the inside makes sense:
The issue now is… how can I connect those two?
(I guess now it became more of a mind exercise for me… I think the better solution would be to hide a transition from exterior to interior somewhere… Not sure how they do this kind of stuff in a game like let’s say Zelda Tears of the Kingdom, going in a cave.
In this case we would then have another issue, the directional light wouldn’t cast any shadows in the outside world too.
But still wondering if there is a way of achieving this with CSG shapes.)