Sloped 3d floor render bug

[Wivicer]

(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:


Map File
Mod File
You'll also need this: https://drive.google.com/file/d/0B4p2zW ... sp=sharing

[_mental_]

Post a complete runnable sample please.

[Wivicer]

Done. Sorry about that

[Graf Zahl]

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.

[Marisa the Magician]

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

[Graf Zahl]

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.

[Enjay]

does it still crap out if you flatten it?

If I flatten it, the glitches go away.

[Marisa the Magician]

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?

[Graf Zahl]

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

[Graf Zahl]

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