[justsomehnguy]

The most notable would be the spiral staircase right in E1M1, leading to the cinema projector booth. It looks perfectly aligned in the 3d view, but if you look at the map you would notice what it consists of the multiple sectors which are misaligned just a bit.

[dividuum]

Not that this contributes a lot to the overall discussion, but from what I remember, the misalignment in that case wasn't necessary. Vertices could have the same coordinate, but it's just easier in the editor to build that stair case if you can actually find and click them.

[moring]

That's how I understood it too. The misalignment was because the editor would automatically turn two one-sided lines (walls) into a single two-sided line and connect the sectors, and mess everything up. The engine itself probably didn't need the misalignment.

The engine DID need the "lots of sectors so you don't see two overlapping sectors at once", which came for free with a spiral staircase.

[justsomehnguy]

You can but you shouldn't, it really mess the engine, making essentially a one-sided... walls-which-arent-till-they-are.

I just made two sectors separately and moved one on top of other.

https://imgur.com/a/uDxMDBp

[justsomehnguy]

https://news.ycombinator.com/item?id=35628351