Re-enabling OpenGL compositing automatically after it crashes KWin at login to KDE Plasma

One of my laptops has NVIDIA Optimus hardware and runs Gentoo Linux with the closed-source NVIDIA driver. Almost every time I logged-in to KDE Plasma for the first time after booting, OpenGL and compositing would be disabled (see screenshot below), and the usual methods of toggling compositing on/off would not work.

KDE Plasma - System Settings - Compositor Settings for Desktop Effects.

I had to perform the following ritual in order to get ‘wobbly windows’ working again:

1. select ‘System Settings’ > ‘Display and Monitor’ > ‘Compositor’
2. click on ‘Re-enable OpenGL detection’
3. deselect ‘Enable compositor on startup’
4. click ‘Apply’
5. select ‘Enable compositor on startup’
6. click ‘Apply’

After having to perform this tedious process almost every time I logged in to KDE Plasma following boot-up, I finally decided to find an automated method of re-enabling OpenGL detection and compositing. I discovered that, when the problem occurred, the value of the variable OpenGLIsUnsafe in the file ~/.config/kwinrc had become ‘false‘. To get things working again I created the Bash script ~/restart_compositing.sh listed below. The script reverts the value of the variable OpenGLIsUnsafe to ‘true‘, reverts the value of the variable Enabled in the same section to ‘true‘ if it happens to be ‘false‘, and restarts KWin. Simple as that.

#!/bin/bash
#
# OpenGL compositing usually crashes KWin when I login, and compositing is then disabled.
# I have to select 'System Settings' > 'Display and Monitor' > 'Compositor' and perform
# the following steps to get compositing to work in the session:
#
# 1. click 'Re-enable OpenGL detection'
# 2. deselect 'Enable compositor on startup'
# 3. click 'Apply'
# 4. select  'Enable compositor on startup'
# 5. click 'Apply
#
# This script enables me to avoid having to perform the above manual procedure.
# This script is configured to run automatically at Plasma Startup - see:
# 'System Settings' > 'Startup and Shutdown' > 'Autostart'
#
edit_kwinrc () {
                # Extract the [Compositing] section from kwinrc
                awk '/\[Compositing\]/,/^$/' $HOME/.config/kwinrc > /tmp/kwinrc-extract
                # Remove the header in the extracted section
                sed -i '/\[Compositing\]/d' /tmp/kwinrc-extract
                # Remove the empty line at the end of the extracted section
                sed -i '/^$/d' /tmp/kwinrc-extract
                # Change the state configured for next login
                if [ $1 == "disablecompositing" ]; then
                    sed -i 's/Enabled=true/Enabled=false/g' /tmp/kwinrc-extract
                elif [ $1 == "enablecompositing" ]; then
                    sed -i 's/Enabled=false/Enabled=true/g' /tmp/kwinrc-extract
                elif [ $1 == "openglunsafe" ]; then
                    sed -i 's/OpenGLIsUnsafe=false/OpenGLIsUnsafe=true/g' /tmp/kwinrc-extract
                elif [ $1 == "openglsafe" ]; then
                    sed -i 's/OpenGLIsUnsafe=true/OpenGLIsUnsafe=false/g' /tmp/kwinrc-extract
                fi
                # Replace the [Compositing] section in kwinrc
                awk 'BEGIN {p=1} /^\[Compositing\]/ {print;system("cat /tmp/kwinrc-extract");p=0} /^$/ {p=1} p' $HOME/.config/kwinrc > /tmp/kwinrc
                cp /tmp/kwinrc $HOME/.config/kwinrc
}
#
# Avoid backing up an incorrectly-edited file
if [ ! -f $HOME/.config/kwinrc.bak ]; then
    cp $HOME/.config/kwinrc $HOME/.config/kwinrc.bak
fi
#
sleep 120s # This delay works for my specific laptop but might need to be adjusted on other machines.
if $( grep -q "OpenGLIsUnsafe=true" $HOME/.config/kwinrc ); then
    edit_kwinrc openglsafe
    edit_kwinrc enablecompositing # Just in case it was disabled as well.
    kwin_x11 --replace & > /dev/null 2>&1
fi
exit 0

I then selected ‘System Settings’ > ‘Startup and Shutdown’ > ‘Autostart’, clicked on ‘Add Script…’ and specified that /home/fitzcarraldo/restart_compositing.sh has to be run at ‘Startup’ (of Plasma). Problem solved.