What

The make up shader always draws the surprising scene like this:
bug-vedio

Platform

both meet this bug on:

• Linux + Intel

  • System: Arch Linux 6.16
  • Processor: i9-12900K integrated graphics
  • Launcher: Official Minecraft Launcher + Optifine 1.21.8-Optifine_HD_U_J6_pre9
  • Version: git commit 9dfa90d
  • Log: minecraft-log
  • (which is recorded in the vedio above)

• Windows + AMD

  • System: Windows 11
  • Processor: AMD integrated graphics (sry i do not know the accurate ID because it is on my gf's computer)
  • Launcher: Official Minecraft Launcher + Optifine 1.21.8-Optifine_HD_U_J6_pre9
  • Version: downloaded from curseforge yesterday)

Reproduce

0. set make-up shader option to option
1. /time set 3600
2. switch to the third-person rear view (the second mode, with the camera behind the player)
3. sail a boat on the ocean surface for about 20 seconds.
4. While staying on the boat, start turning the boat and camera (both horizontally and vertically, e.g. including turn the third-person rear camera under the water).
5. After that, look up toward the bright sun.

(I hope this reproduce guide will work.)

Thank you! I love this shader and I'll star it on github :)

Thank you for your detailed report — it's essential for being able to reproduce the bug, and many people don't provide one.

Despite that, I’ve been unable to reproduce the bug so far. I can’t download the exact version of Optifine you’re using. Trying with the latest version, at least on my computer, I can’t even get shaders to work properly (none of them).

Lately, I’ve been having trouble getting some versions of Optifine to work correctly. But that seems to be an issue with Optifine itself, or with how it interacts with my hardware. In your case, I’m afraid the problem might be some kind of image buffer corruption that depends on the specific hardware/software combination you have, along with the bloom effect from the shader, causing that white glare.

If you're not using a mod that strictly requires Forge, or only exists for Forge, I’d suggest trying Iris on Fabric instead of Optifine on Forge. That might fix the issue — or at least help isolate some variables.

There are also other mods for Fabric that can help with performance, like Lithium, Entity Culling, etc., and they’re fully compatible with shaders.

I personally use the Prism Launcher to run and manage different Minecraft versions and mod loaders like Forge or Fabric. It’s much more convenient than the official launcher, and it’s safe since it’s open source. I see you’re using Linux — you can easily install it via Flatpak.

Thanks again for your report.