How to make picom clip all windows but "background" windows

[SollyBunny]

Platform

Arch Linux

Environment

dwm + alpha

picom version

vgit-89c2c

Config

--transparent-clipping

Steps to reproduce

I have a live background which uses a window embedded in the background (https://github.com/sollybunny/glsltoy).

With --transparent-clipping the window gets clipped (as somewhat expected)

But with --transparent-clipping and --transparent-clipping-exclude="name *?= \"glsl\"" (the window's name is "glsltoy") nothing happens (presummably the background is barred from clipping any windows)

[SollyBunny]

expected behaviour (when dragging the windows over eachother, only the top most terminal should show and then merge with the background)

actual behaviour (the background is removed underneath all windows)

[absolutelynothelix]

the transparent-clipping option makes windows have the wallpaper behind them. the wallpaper for picom is an image that a root background pixmap atom points to. your terminals become black because you don't have it set.

the transparent-clipping-exclude option disables the transparent-clipping option for matched windows, iow makes windows have the real content behind them.

you want the transparent-clipping option to make windows have a particular window (or layer) behind them. i don't think that it's currently possible so i consider this an enhancement.