In some instances the examples may look like this:

This is due to somewhat old pygame/SDL versions being shipped with Raspberry Pi OS.

Raspberry Pi 3 etc

On Pi 3B+, Pi Zero and other pre-Pi4 boards you can update pygame from pip to fix glitchiness:

sudo python3 -m pip install pygame --upgrade

Raspberry Pi 4

On Pi 4, you should upgrade pygame as above but it will probably result in this error when you try and run an example:

* failed to add service - already in use?

I believe this, followed by the unhelpful hard exit(1) is caused by this code: https://github.com/raspberrypi/userland/blob/97bc8180ad682b004ea224d1db7b8e108eda4397/interface/khronos/common/linux/khrn_client_rpc_linux.c#L214-L216

In any case the only way to work around this seems to be by compiling SDL from source... 😬 ... and using your shiny new SDL to replace the system one used by pygame.

You can do that with the following steps:

wget https://www.libsdl.org/release/SDL2-2.0.14.zip
unzip SDL2-2.0.14.zip
cd SDL2-2.0.14
./configure --enable-video-rpi --enable-video-kmsdrm --prefix=`pwd`/install
make
make install

This will install SDL into an "install" directory within the "SDL2-2.0.14" directory, so don't delete it. (You can change the --prefix when configuring to something like /opt/SDL2-2.0.14 if you're so inclined, it doesn't really matter where you put it.)

Once built the new SDL libraries will be available in install/lib, find the full path by typing:

cd install/lib
pwd

In my case the path is /home/pi/SDL2-2.0.14/install/lib.

Now when running an example from this repository, you should prefix the command line with LD_LIBRARY_PATH=/home/pi/SDL2-2.0.14/install/lib, for example:

sudo LD_LIBRARY_PATH=/home/pi/SDL2-2.0.14/install/lib python3 clock.py

If everything is set up correctly on your Pi 4 you should see "Using driver: kmsdrm"