Doom SourcePort Texture Glitch

I was playing Doom on the Zandronum sourceport today and noticed this wierd texture glitch/artifact on level Nirvana, I have never seen this before and I played this level dozens of times. Is this caused by my GPU or caused by a software bug or driver problem?

22 minutes ago, GeneralHiggs said:

What is this, a screenshot for ants?

No that's always been there, the ceiling has been pushed up too high and the upper wall textures are missing. You don't usually notice it because in vanilla you can't look up and the plane rendering masks it. In the software renderer, floor/ceiling texture drawing only stops when it reaches another plane or texture, so a missing upper/lower texture will cause the plane to flood the missing area.

You sure it looks fine Edward850? Watch this clip I recorded with Nvidia Shadowplay.

Yes, it's "expected" to happen, as noted I said that the problem was originally easy to miss. You are seeing it more plainly because you have freelook, have a higher resolution and a 3D polygon renderer the game was not originally designed for. Here's how it looks in chocolate-doom:

It's still there, but because you are using a GL renderer which renders planes very differently, the issue sticks out, but it was indeed always there.

I did watch a video of someone playing this level on the same port and this appears in there game as well. I guess Zandronum pushes the limitations of ID Tech 1 engine. I am glad to hear this is intended and not issue on my end.

If it bothers you, play in GZDoom where the glitch is worked around with a run-time patch.

8 hours ago, GeneralHiggs said:

I did watch a video of someone playing this level on the same port and this appears in there game as well. I guess Zandronum pushes the limitations of ID Tech 1 engine. I am glad to hear this is intended and not issue on my end. 

It's not so much "pushing the limitations" but that the map is plain and simply not designed properly in this place. With the software renderer it just so happened that the glitch didn't show or the map would never have been released in its actual state. In the end it can be blamed on the original editor which had no sector editing mode, all sector properties had to be set on the linedef - which made it very easy to produce open sectors that then could cause render glitches.

But when using different rendering techniques like polygonizing the sector, it cannot be handled anymore.