Support user defined shaders

[coreymwamba]

This is more of an feature request: when I used to use i3 I also used picom's legacy glsl shaders to turn my screen from RGB to grayscale, or invert the colours. Having looked at the source code for scenefx (after trying—and failing—to write a script that could modify gamma ramps in wlroots) I see that it uses gles fragment shaders.

So would it be possible to add that functionality to scenefx (and thus swayfx)?

[WillPower3309]

This is a good idea! I think what we want here is essentially WillPower3309/swayfx#110

[coreymwamba]

I'm really sorry I can't help much more—I'm still learning C! But am I right in thinking that you'd need to modify the files in include/render/fx_renderer?

[WillPower3309]

tracked by #60