Zandronum

I converted and modified the map from freedoom, it is not included in the new release of freedom now. But there is a problem, for some reason in some places the middle textures become translucent, although I did not make them so in the editor. On the map, translucent middle textures have only two lines.
An important feature, I converted this map from boom format to udmf, but with namespace=doom. Not all ports support this, but in zandronum the game works fine, except for the wrong translucency.

In GZDoom, for example, namespace=doom is not supported and the game does not work correctly, but with the translucency of the middle textures everything is fine.

Below I provide screenshots and a file for this map.

Spoiler: (Open)

Screenshots of zandronum 3.2.1.
here are the middle textures that should be translucent



here, which should not




here are screenshots from GZDoom






Here is a link to the map
https://www.mediafire.com/file/r0el53a9 ... 1.zip/file

It's due to a bug in the UDMF loader when handling maps whose line specials has to be translated to ZDoom's native line special numbers.

Basically, in UDMF every line has an ID of -1 by default, but Doom didn't really have line tags in the way ZDoom uses them so the first argument is used since it typically controls what to affect. The loader is setting the tag for each line to its ID, but the first argument should be used instead. The map translator is then setting the line's first argument back to its tag, since that's what ZDoom's TranslucentLine expects. Basically fun vanilla compatibility stuff resulting in the line having the wrong tag.

TranslucentLine checks affects every line up until that point whose IDs matches the tag it's expecting - since every line has ID -1, and the line's first argument is also -1, it is setting the alpha of every line up until that point. On this map specifically, that's the first 1280 lines in the map, but it's only visible on a few since translucency only shows on double-sided mid textures.

It was fixed upstream in 03ccf03.

Thank you