ZDoom

Fixed. This came from a bad alpha value that got set for sloped 3D floors.

I suspect some uninitialized render style somewhere. If this was just rendered with regular translucency by accident it wouldn't glitch this badly.

Ah, I knew it. sloped 3d floors and any form of transparency just don't mix.

I assume what happens here is that the software renderers treat the texture as opaque, but on hardware it tries to do alpha blending of some sort and fails spectacularly?

[quote="Marisa Kirisame"]does it still crap out if you flatten it?[/quote]
If I flatten it, the glitches go away.

That really shouldn't make a difference in the final image. But it's an idea. If it thinks the texture has an alpha channel and selects a bad render mode it might glitch.

It seems that that texture has an alpha channel (although it's all at 255), does it still crap out if you flatten it?

All I can say is that it's something with the texture - but there's so much interference in that bunch of data that I can't find what precisely causes it. Globally replacing the METSAND texture in the map with a stock Doom 2 texture makes the glitch disappear.

Done. Sorry about that

Post a complete runnable sample please.

(NB: this only occurs in the hardware renderer)

I have created a map with a 3d floor that has its bottom face sloped. The upper face is flat. In the softpoly renderer it looks fine, but in the hardware renderer it looks like this:

[img]https://i.imgur.com/JpfbFnyl.png[/img]
[url=https://drive.google.com/open?id=1kI2BYjNdGHuIBqgui_RlHTY1a5URk6DT]Map File[/url]
[url=https://drive.google.com/open?id=19Mco4mkGblzqdFrAuEf5ffJqqgOYnEqL]Mod File[/url]
You'll also need this: https://drive.google.com/file/d/0B4p2zWkJEFFtNUtkUDZJcWlOQXc/view?usp=sharing