jorjic
commented
2 years ago What's the map in the example image called? I'll try to reproduce it in Garry's Mod and other Source games. You mention it was resolved since L4D; maybe the fix is somewhere in this monolithic commit pushed to the Source SDK 2013 base. Maybe it was fixed in mapbase. The best approach is to reproduce the error first then find which games you can't reproduce it with and hunt down the fix from there.
as it is an engine bug.
Source is funny about what's considered engine code and what isn't. The Source SDK 2013 base provides everything that isn't engine code, which is what Garry's Mod originates from. If the problem really is in the engine, we're probably out of luck.
Also, dump mat_info while you're at it.
Volantarius
So there's this old source engine bug with antialiasing that causes little seams in displacements and brushes(though I've not seen it happen on brushes, other mappers have said that it can) that appear from far away, but only when anti-aliasing is enabled. Blueberry pie thinks its some kind of texture filtering bug that causes darker lightmaps to bleed into lighters ones, this issue has been resolved since l4D. Again, this bug doesn't occur all the time, certain conditions need to be met for it to happen, as said previously, usually this happens in bright environments with stark shadows. I was on the default gmod branch, but it's sure to occur on all branches as it is an engine bug.