Given a set of points from a complex polygon, triangulates the points of the smallest number of triangles required to fill that polygon.
Particularly useful for breaking down concave shapes (which can't be drawn natively by OpenGL) into triangles (which OpenGL is happy with)
An example is here: http://forum.openframeworks.cc/index.php/topic,10582.0.html
Uses the Triangle library, a 'Two-Dimensional Quality Mesh Generator and Delaunay Triangulator', by Jonathan Richard Shewchuk.
Uses the 'point inside polygon' algorithm by Theo Watson.
example-opencv by James George - requires ofxOpenCv - builds polygons based on frame differencing from your webcam
example-simple by Andrew McWilliams - requires no addons - just demonstrates a concave polygon