Run picom with LightDM

[Monsterovich]

I was wondering if picom would work in LightDM. The modesetting driver only recently introduced TearFree, and without it everything without compositing shows screen tearing, including LightDM. Who cares about tearing in LightDM? I'm a perfectionist. :D

Create a file /etc/lightdm/lightdm.conf with the following content.

[SeatDefaults]
display-setup-script=$path_to_your_script$/lightdm.sh

lightdm.sh

#!/usr/bin/env bash

picom --daemon --config $path_to_config%/picom.conf

You need to explicitly specify the config, because lightdm is run by the root and therefore looks for the config in the root home folder.

That's it, goodbye tearing. The compositor will also run in a normal user session as if it was running when the DE started. At least in Xfce, it works.

Update:

You can also run picom with --monitor-repaint flag to check if it truly works. All refreshed parts of the screen will be displayed in red.

https://www.youtube.com/watch?v=VcyOHm_2ths

[ghost]

You can also check here which I just found from arch wiki reference: https://ubuntuforums.org/showthread.php?t=2144468&p=12644745#post12644745