Add support for CTM (color transformation matrix)

[sfiedler0]

I am currently working on Asahi Linux with Hyprland. Everything works perfectly, except for night light. After some research I found AsahiLinux/docs#67.
The mentioned gammastep issue had a comment pointing to an issue in wlroots. As Hyprland is independent now (and uses aquamarine which does the gamma LUT stuff), I thought it'd be a great idea to implement the CTM here too.

[vaxerski]

hm, the problem is that wl-sunset et al that control this on hyprland via the wlr gamma protocol can only provide a ramp, not a matrix. How would we control the amount of red-shifting?

[sfiedler0]

I don't know exactly how KDE did it, but they have CTM support merged: https://invent.kde.org/plasma/kwin/-/merge_requests/3296

[vaxerski]

they dont have to support stuff like wl-sunset though (and they dont)

while we do

[sfiedler0]

They seem to have updated some gamma control code too though. So it looks like they use the CTM through gammaControl if I interpreted the C++ code right (I like programming, but not in C++).

[vaxerski]

no, they didnt

[sfiedler0]

So CTM control is ready for a new wlr protocol?

[vaxerski]

wlr makes no sense (we arent wlr anymore)

I'd either:

• find out a method to convert gamma ramps to a ctm
• ditch the external apps altogether, just make the ctm a configurable thing in the config
• make a new hyprland protocol for ctm - could actually be nice with a hyprland-provided utility for night light

[vaxerski]

looking at drm support it seems that all drivers support CTMs. Well, all that matter. AMD, Nvidia, Intel.

[vaxerski]

I'll try to draft a protocol later today if I don't forget at hyprland-protocols. Ping me tomorrow if I don't

[vaxerski]

closing this as aquamarine is done. Hyprland see hyprwm/Hyprland#8023, client see https://github.com/hyprwm/hyprsunset.

If you compile from 8023 you should be able to use hyprsunset no problem, tested on my machine, but lmk if it works on apple.

cheers