[g3.4pre-241-g4870cc73e2]TEXTURES w/ add-pixels render wrong

Bugs that have been investigated and resolved somehow.

Moderator: GZDoom Developers

Forum rules
Please don't bump threads here if you have a problem - it will often be forgotten about if you do. Instead, make a new thread here.
Post Reply
User avatar
Xane123
Posts: 165
Joined: Tue Nov 24, 2015 1:58 pm
Graphics Processor: nVidia (Modern GZDoom)
Location: Inwood, WV
Contact:

[g3.4pre-241-g4870cc73e2]TEXTURES w/ add-pixels render wrong

Post by Xane123 »

(It's hard to fit the full title into the subject field here, but hopefully you understood what it was.)

Here's a bug that's been in GZDoom for...many versions, probably back to the engine "floatification". It's hard to describe, but 3D floors, reflective surfaces (the old plane reflections), and walls under an additive texture appear to be rendered incorrectly if they use a TEXTURES-based texture that has layers that use additive blending. Any pixels the additive layers don't affect on the texture appear to turn transparent, allowing the player to see GZDoom culling the environment through walls and through surfaces they shouldn't be able to see through.

What's strange abut this bug is it only seemingly occurs when using my game's palette. If I convert all the patches to the Doom palette, it doesn't occur but this test WAD that includes my game's palette showcases the three cases I wrote about above. Just run it with Doom II and (after a glitchy title screen) you'll see three things, all showcasing this bug:

LEFT: Transparent mid-textures (both types) over the offending texture, proving both cause the glitch.
MIDDLE: Reflective floor; This lets the player see the reflected room clearer than otherwise.
RIGHT: Transparent 3D floor; Solid 3D floors are also affected by this glitch though not demonstrated here. This applies to all renderers, unlike the other two, which are OpenGL-only.

Here's screenshots of the two renderer types:
OpenGL renderer; All three oddities can be seen.
OpenGL renderer; All three oddities can be seen.
Software renderer; This is only one of the four variants of this renderer, but it's the same in all four, only the 3D floor oddity is here.
Software renderer; This is only one of the four variants of this renderer, but it's the same in all four, only the 3D floor oddity is here.
Attachments
bug_texglitch.wad
Test WAD. Use Doom II.
(202.78 KiB) Downloaded 24 times
User avatar
Graf Zahl
Lead GZDoom+Raze Developer
Lead GZDoom+Raze Developer
Posts: 49056
Joined: Sat Jul 19, 2003 10:19 am
Location: Germany

Re: [g3.4pre-241-g4870cc73e2]TEXTURES w/ add-pixels render w

Post by Graf Zahl »

The problem comes from your PNGs which contain an alpha channel which of course gets blended into the final composited texture.

If you do texture compositing you should avoid that because how the alpha gets used may not be what you'd expect in many cases.
Post Reply

Return to “Closed Bugs [GZDoom]”