White lines flicker near torches in dark areas

[diesaifa]

Checklist

• I am reporting a defect, not asking for help
• I have searched existing issues and this has not been reported
• I have reduced my mod list to the minimum required to reproduce this issue (see below)

Bug Description

When I add Modernfix to modpack it causes white lines flicker near placed torches in dark areas. It happens with only Sodium, Ferrite Core and Modernfix. The lines are very tiny but you can still see them right near the top of the torch (left from it):

Minecraft.2026.07.10.-.05.15.39.02.mp4

In heavy modded environment this issue becomes more noticeable (lines become bigger and appear not only near torch):

Minecraft.2026.07.10.-.04.52.12.01.mp4

The funny thing is that I added Modernfix hopping to fix another but similar issue:
White dots flickering near equipped torch in the hand (or offhand) in dark (but slightly light) areas. I didn't record it but I found post where you can actually see these 2 bugs together (dots and lines) (lines appear too because the person uses dynamic light mod I assume):
https://www.reddit.com/r/feedthebeast/comments/1rbt4p6/white_lines_appearing_in_dark_places_in_my/

So I added Modernfix to fix dots and it actually fixed them but introduced lines problem. Although I don't think the dot issue is related to any specific mod, because it fixes itself when I randomly add or remove different mods. Perhaps it's a sodium issue, I don't know.

Minimal Mod List

• modernfix 5.27.15
• Sodium 0.8.12
• ferritecore-7.0.3

1.21.1 Neoforge

Reproduction Steps

1. download Modernfix
2. load the game
3. go to dark area (cave)
4. place a torch
5. move back a little from the torch
6. wait to see lines flickering near the torch

Diagnostic Info

latest.log

[embeddedt]

This sounds like a longstanding flaw in newer Sodium versions. The short summary is that Minecraft places all block textures beside one another on something called a texture atlas, then keeps track of what region on the atlas should be displayed for each block face. One of Sodium's optimizations reduces the precision of this tracking to save memory. This can cause a pixel from an adjacent block texture to leak into the intended one at some angles (for technical reasons I won't get into here). On solid blocks the effect is not always noticeable, but on blocks whose texture is surrounded by transparent pixels (e.g. torches) it can be very obvious, especially if a light pixel appears on it in a poorly lit area.

In my fork (Embeddium) as well as older versions of Sodium it was possible to avoid this by disabling that specific optimization (option called "Compact Vertex Format") while keeping the rest of the benefits of the mod. Upstream Sodium has not provided that option, to my knowledge, since 0.3/0.4, so your only recourse would be to remove it. If my theory is correct this will fix the problem. (Note that I have not used versions of Sodium newer than 0.5.x due to their restrictive license, so I recommend double checking they haven't added the option back.)

As for why adding/removing ModernFix changes the behavior, ModernFix changes the algorithm used for stitching the atlas. This means different textures will be placed next to one another with or without it present, which may hide or reveal the issue.

[diesaifa]

Unfortunately removing Sodium is not an option for me cause of Aeronautics mod and there is no option to disable Compact Vertex Format in the newest version of Sodium

For now I disabled mixin.perf.faster_texture_stitching and it helped with lines
There are no dots too, but I guess it's not for long cause they may randomly reappear if I decide to add some random mod

I wonder why there was removed this option to disable Compact Vertex Format in Sodium

[diesaifa]

no, the dots still appear. So when used mixin.perf.faster_texture_stitching there are no flickering dots near equipped torch but there are lines near placed torch. This thing is so annoying

[zen-crab]

I recommend double checking they haven't added the option back.)

They have not and I doubt they ever will because whenever this issue is raised in their discord, Jellysquid just pushes the blame on other mods.

[basdxz]

I'm curious if this issue persists with smooth lighting turned off, in particular since the issue is happening while the camera is still.

[zen-crab]

I'm curious if this issue persists with smooth lighting turned off, in particular since the issue is happening while the camera is still.

Still happens. The only setting I have ever found that fixes the issue is disabling compact vertex format.

[embeddedt]

I do not see any reasonable solution I can provide for this on ModernFix's end, short of patching Sodium to have a CVF toggle again, which is wildly out of scope and also not possible for licensing reasons.