Based on the paper "Efficient Clipping of Arbitrary Polygons" by Günther Greiner (greiner[at]informatik.uni-erlangen.de) and Kai Hormann (hormann[at]informatik.tu-clausthal.de), ACM Transactions on Graphics 1998;17(2):71-83.
Available at: http://www.inf.usi.ch/hormann/papers/Greiner.1998.ECO.pdf
This work was created for educational purposes only, as an implementation in Python of the above algorithm, for a class in Graphical Computation.
To study the algorithm, inspect the file polygon.py. It can be imported and used in other contexts (i.e., not OpenGL).
> import polygon
> help(polygon)
> from polygon import *The command line interface (polyclip.py) is provided for demonstration or testing purposes, using OpenGL.
Supports Python 2.5 or later.
Requires PyOpenGL (version 3 as of this writing). If you have pip, install is easy:
pip install pyopengl
Supported operations are: union, intersection and difference.
Subject and clip polygon can be defined per command line option. Defaults for the subject and clip polygon are set at the beggining of the file for easy edit, but they can be overriden from the command line using the options --subj-poly and --clip-poly.
Example:
polyclip.py --subj-poly="1.5, 1.25; 7.5, 2.5; 4, 3; 4.5, 6.5"
Type polyclip.py -h for available options. Press Esc to exit.