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IDProjectCategoryView StatusDate SubmittedLast Update
0004345Zandronum[All Projects] Bugpublic2024-07-20 02:282024-09-05 20:11
ReporterDrPyspy 
Assigned To 
PrioritynormalSeveritymajorReproducibilitysometimes
StatusnewResolutionopen 
PlatformOSWindows 10OS Version
Product Version 
Target VersionFixed in Version 
Summary0004345: Textures/sprites with alpha frequently turn opaque
DescriptionMe and some buddies I've tested with have discovered a worrying graphical glitch in Zandronum 3.2 (alpha-240414-1910), where sprites and textures with transparent bits will randomly swap between looking correct and being opaque. I tried looking into it and saw that similar issues have cropped up in the past in GZDoom and Q-Zandronum, so I'm hoping getting some more eyes on this issue will help.

The following is a video showcasing how the sprites and textures start out as opaque:'https://www.youtube.com/watch?v=UtoI44JnXeg [^]' You'll notice that things are momentarily fixed by swapping the indoor room's ceiling to a sky texture (the first room uses a ceiling portal, so it technically doesn't have a sky texture on the ceiling, and doesn't have any affect on whether or not the bug occurs.)

This next video is a version of the same test map with some additional features being used:'https://www.youtube.com/watch?v=UtoI44JnXeg [^]' An important note is that with the decals present, the graphics no longer start out opaque, but will still glitch out when moving around or firing.

Here is some footage of it occuring on an actual map from my project Tomb Fetus:'https://www.youtube.com/watch?v=CeXW5ttHnWU [^]' The symptoms here are a bit weird, happening on the textures and sprites at separate points, and seemingly being affected by the player's subtractive dynamic light.
Steps To ReproduceThe included PK3 includes two variants of the test map: one with decals on the walls, and one without, which determines whether the graphics will start out bugged or not. Rockets impacting the walls will turn some of the graphics transparent again, but it won't stay like that for long if you move around or shoot the walls.

1. Load up a map (MAP01 to (hopefully) start with transparent textures, MAP02 otherwise)
2. Shoot walls or move around
Additional InformationHere is my hardware and driver info:

Graphics Card: Radeon(TM) RX 460 Graphics
Driver Version: 31.0.21912.14
Attached Files? file icon zandyalphabug.pk3 [^] (86,643 bytes) 2024-07-20 02:28
? file icon TombFetus_zandyalphabug.pk3 [^] (149,084 bytes) 2024-07-26 15:31
? file icon zandronum-legow.ini [^] (27,781 bytes) 2024-07-26 15:31
? file icon TombFetus_zandyalphabug_technicallyfixed.pk3 [^] (151,252 bytes) 2024-09-05 20:04

- Relationships

-  Notes
User avatar (0023816)
unknownna (updater)
2024-07-25 20:13

 I'm unable reproduce this on my older laptop with an integrated GeForce 820M, driver version 389.12. Could you upload a copy of your ini?
User avatar (0023824)
DrPyspy (reporter)
2024-07-26 15:33

 Thanks for checking this out! I've uploaded my ini and an updated version of the test PK3 that includes a new map that should consistently start out with the bug visible, and is unaffected by any sort of interaction with the world (aside from moving and looking around in the outdoor area.)
User avatar (0023840)
unknownna (updater)
2024-07-28 01:08
edited on: 2024-07-28 01:09

 Hi, after trying out the examples with your ini and messing around with all the settings in the Nvidia control panel, I still couldn't reproduce the issue on my hardware. It must be some hardware or driver error with AMD perhaps.

Does it also glitch out like this in'https://zandronum.com/downloads/upstream/gzdoom-1.8.06windows.zip [^]' ?
User avatar (0023842)
DrPyspy (reporter)
2024-07-28 15:07

 I can confirm it happens in that build of GZDoom as well! The glitches are mostly if not completely identical.

As a quick test, I also checked on the most recent version of GZDoom using both OpenGL renderers, and the glitches do not appear. Might not be super helpful considering the rendering stuff is probably super far removed from what Zandronum uses, but it is worth noting!
User avatar (0023847)
Kaminsky (developer)
2024-07-29 14:52
Quote from "DrPyspy"
As a quick test, I also checked on the most recent version of GZDoom using both OpenGL renderers, and the glitches do not appear. Might not be super helpful considering the rendering stuff is probably super far removed from what Zandronum uses, but it is worth noting!


By chance, do you know the earliest version of GZDoom where this glitch stops? Depending on how different the rendering code of that version is from ours, it might not be feasible to backport the changes right now. Thanks for checking GZDoom 1.8.6 though!
User avatar (0023866)
DrPyspy (reporter)
2024-07-31 00:35

 Did a quick dive, and it seems GZDoom v2.0.03 is the earliest version where the glitch stops happening. Here's the link to the version I used:'https://zdoom.org/files/gzdoom/bin/gzdoom-bin-2-0-03.zip [^]'

Hopefully this can be of help!
User avatar (0023991)
DrPyspy (reporter)
2024-08-31 21:31

 UPDATE: This bug was fixed in Q-Zandronum as of today! Tested it myself and I can confirm so far that the problem no longer occurs. Hopefully these fixes can make their way over to Zandy soon 👀
User avatar (0024014)
DrPyspy (reporter)
2024-09-05 20:11

 I've uploaded a new version of the PK3 that includes a shader modification that seems to fix the issue on my and some others' ends! It is based on one of the adjustments Q-Zandronum made to fix the alpha issue, which discards any pixels with an alpha less than or equal to 0.01:

---

vec4 frag = Process(vec4(1.0));

// alpha testing
if ( frag.a <= 0.01 ) discard;

---

The reason why I'm hesitant to call this a 'fix' with certainty is because Q-Zandronum changed a lot of rendering code in addition to the shader change, so this is only one part of a bigger fix as far as I can tell. If nothing else, though, this'll work as a band-aid fix for anyone else who is experiencing this issue.

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- Issue History
Date Modified Username Field Change
2024-07-20 02:28 DrPyspy New Issue
2024-07-20 02:28 DrPyspy File Added: zandyalphabug.pk3
2024-07-25 20:13 unknownna Note Added: 0023816
2024-07-25 20:13 unknownna Status new => feedback
2024-07-26 15:31 DrPyspy File Added: TombFetus_zandyalphabug.pk3
2024-07-26 15:31 DrPyspy File Added: zandronum-legow.ini
2024-07-26 15:33 DrPyspy Note Added: 0023824
2024-07-26 15:33 DrPyspy Status feedback => new
2024-07-28 01:08 unknownna Note Added: 0023840
2024-07-28 01:09 unknownna Note Edited: 0023840 View Revisions
2024-07-28 01:10 unknownna Status new => feedback
2024-07-28 15:07 DrPyspy Note Added: 0023842
2024-07-28 15:07 DrPyspy Status feedback => new
2024-07-29 14:52 Kaminsky Note Added: 0023847
2024-07-29 14:52 Kaminsky Status new => feedback
2024-07-31 00:35 DrPyspy Note Added: 0023866
2024-07-31 00:35 DrPyspy Status feedback => new
2024-08-31 21:31 DrPyspy Note Added: 0023991
2024-09-05 20:04 DrPyspy File Added: TombFetus_zandyalphabug_technicallyfixed.pk3
2024-09-05 20:11 DrPyspy Note Added: 0024014




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