Fix gamma slider via pixel shader #178

[ModMaker101]

Description

This PR fixes the gamma slider so it properly affects scene brightness on all platforms. Instead of relying on DXGI system level gamma, gamma is now applied directly through the light-texture pipeline

Changes

Previous Behavior

• Gamma slider did almost nothing.
• Originally attempted hardware gamma via IDXGIOutput::SetGammaControl, which was unreliable.

Root Cause

• The engine never applied gamma in a sofware path.
• Hardware gamma APIs were inactive in the environments people were using.

New Behavior

• Gamma slider now affects global brightness consistently.
• A small toe lift keeps shadows readable when brightend.
• Works per-player in split-screen.

Fix Implementation

• Removed reliance on DXGI.
• Added software gamma curve inside updateLightTexture, with clamping and toe correction
• Verified in day/night, caves, underwater, and rain.

Related Issues

• Fixes Gamma slider has no effect #178

Before:

After:

Not entirely too much of a difference during the day.

Before:

After:

Now I'm WAY to lazy to try and time it up to get a lighting strike, but yeah the gamma bar also works too:

2026-03-04.15-45-41.mp4

[ModMaker101]

Oh yeah sorry for the quality, GitHub only allows 10MBs.

[void2012]

goated PR, thanks

[ModMaker101]

Yeah, no problem.

[hartelex]

Nice. Wanted to report the gamma slider doing barely anything as a bug, but I guess I don't have to.

[DFelipehDEV]

idk if its the video quality but i remember console edition having a way more agressive gamma setting(also i believe it affected the ui)

[gizmogoat]

LCEMP's gamma fix seems most accurate if we want to merge that in. The following images are 50% gamma and 100% gamma:

[void2012]

@ModMaker101

[ModMaker101]

My implementation isn't intended to replicate the LC gamma curve it's designed to provide a software fix for the gamma that fixes the slider not doing anything. LCE IIRC used a much more aggressive non-linear curve. My PR does not aim to match that behavior. Instead, I'm applying a standard gamma function with a small toe lift. If we ever decide to target the LC gamma profile, we can add that as a separate preset. But this PR's goal was to make the gamma slider functional.

[ModMaker101]

And I forgot to say, but in ICEMP they use post processing for the gamma. Mine is built into the lighting pipeline directly. But I am working on a commit to make it more LC-like.

[void2012]

Okay, converting to draft.

[ModMaker101]

Yeah, I'll probably have it out by the end of the day.

[ModMaker101]

@void2012 ready for review. One caveat is I kept getting an exception for multiplayer thing which is in progress so I wasn't able to test split-screen.

[void2012]

Ask wine people to test and this can be merged.

[ModMaker101]

I had someone test it for me and they said it was all working @void2012 .