Computer graphics artwork. It's raster graphics pendulum-balls implemented by using NURBS curves.
Open pendulum.py file, download required modules and run the script. The resulting file will be saved with the name circle.gif. There is a demo file named demo which demonstrate artwork.
Balls are created by drawing two NURBS curves which rotated in desired angle and shifted to certain place. After the first ball collide second one they exchange their colors, first ball stops and second one starts moving. While moving ball's border line "opens" and "closes" in the opposite side.