ZDoom

I wonder why other Doom ports don't use 3D lines from Risen3D? I tried using it for fences and ladders and I found it very convenient for mapping.
This is not a 3D floor. You can see how it looks in the tutorial: https://md2.sitters-electronics.nl/tut_lines.htm

There's multiple ways of creating what you're describing in regular Doom / GZDoom already. GZDoom has 3D floors, vanilla can create ladders with miniature 24-high stairs (1 pixel thick, stairs as steep as you need) with a ladder mid texture in front. UDMF also has a flag IIRC that enables players to jump over solid mid textures set by how tall the mid texture is + its offset.

That feature originates from Eternity and ZDoom has been supporting it for a long time in all map formats.
What I do not know is if Risen3D's is the same thing.

Do I understand correctly that you are writing about the 3D middle textures described in these links?
https://zdoom.org/wiki/3D_middle_texture and https://eternity.youfailit.net/wiki/3DMidTex_tutorial

Risen3D uses a completely different approach, very different from 3D mid textures. It allows you to set the distance of the line from the floor and its size (vertically).

I recorded a video with a test map, where all the fences are made exactly like this. You can jump over them. I also added ladders, which are also made using 3D lines.
https://media.mas.to/media_attachments/ ... ea7446.mp4

Basically they are functionally identical to 3D mid textures (project a texture that has collision) but with a different implementation, the main difference in features is that you explicitly select the height of the texture and it'll be clipped to that size.

It suddenly seemed to me that this gives a theoretical possibility to make textures over textures in one linedef. After all, you can set not only the distance from the floor and its vertical size for one texture. But also an array of textures, each with its own distance from the floor and its size.

I'm not a programmer, so I could probably be wrong.

I managed to do it like in Risen 3D: https://imgur.com/HivRJKn


It turns out it's not difficult at all if you know, this information helped me:

https://zandronum.com/tracker/view.php?id=3115
https://zandronum.com/tracker/view.php?id=3191

Only in physics it's not exactly a ladder, you can't hang on it, you can't change the direction of movement down. It reminds me of a jump pad.