[g3.4pre-197-g0affc119f]Additive mid-textures break fog

[Xane123]

I was developing my game recently and noticed some walls looked too dark, like buildings under glass windows and the lower half of one building I made which had liquid behind glass above it. Downloading the latest GZDoom from DRD Team (g3.4pre-197-g0affc119f) revealed the bug is still there, so I made a demonstration WAD. Run that with Doom II as the IWAD and you'll be presented with two crates and two SHAWN2-parts lowered from the ceiling.

bug_brokenfog.wad

WAD demonstrating bug.

(7.65 KiB) Downloaded 23 times

• The first crate has a MIDBARS texture with normal rendering, which leaves the red tint correctly on the crate below it.
• The second crate is the same but has additive rendering on the mid-texture, which makes it use the default black fog for some reason.
• The two ceiling ones to their right are there to show that the additive mid-texture doesn't glitch lowered ceilings, only raised floors.
• I've also noticed that if a sidedef if affected by this glitch, any materials like specular/normal don't appear.

Screenshot showing materials not working; Left is an upper linedef, right is a lower linedef under additive glass.

EDIT: Whoops, forgot to put this in the OpenGL bugs forum, but maybe the bug exists in the software renderer too...?

[Graf Zahl]

The reason why this happens is quite simple: To render additive stuff with fog, the fog color needs to be disabled, and that didn't get reset when the lower parts got done.

[Xane123]

Ah, that was a quick fix! Now those areas in my game look correct, but I've noticed a TEXTURES texture with a blended transparent image within it now lets me see through walls below the additive mid-texture, but this is a problem that happens with anything transparent, like 3D floors and reflective floors. I'll have to come up with a test WAD for this somehow (as it uses graphics from my game, which don't use Doom's palette) then start a new bug report on this glitchy texture-rendering which I've noticed in GZDoom for many versions.

The lower wall here is now strange-looking.

EDIT: Seems the texture has something with additive rendering in it; Here's the glitched texture's TEXTURES definition:

Code: Select all

Texture "CITYWIND", 66, 132
{
	XScale 1.025
	YScale 0.515
	Patch "P_SPNES1", -406, -4
	{
		Rotate 90
		Blend "#3A4EA5"
	}
	Patch "P_SPNES1", -406, 62
	{
		Rotate 90
		Blend "#3A4EA5"
	}
	Patch "QBLOCKT0", 1, 1
	{
		Blend "#9AD6F5"
	}
	Patch "QBLOCKT0", 1, 67
	{
		Blend "#9AD6F5"
	}
	Patch "P_CFOVER", 1, 1
	{
		Alpha 0.20
		Style Add
	}
	Patch "P_CFOVER", 1, 67
	{
		Alpha 0.20
		Style Add
	}
}

[Graf Zahl]

Please post a runnable example in a separate report. This one will appear rather quickly, now that it is in Closed Bugs.

[Xane123]

Please post a runnable example in a separate report. This one will appear rather quickly, now that it is in Closed Bugs.

Okay. I posted about this other bug here.