gfxpoly is a library for doing geometric polygon operations.
(like polygon intersection, union, hidden surface removal, stroke to
 outline conversion, wind rule conversion etc.)
It aims to be more easily embeddable than e.g. GX, livarot or CGAL, faster 
and more stable than libart, and is distributed under a non-commercial 
license (BSD-2).

It's using the algorithm from Hobby [1] with a few additional ideas 
from Hershberger [2] and Bhattacharya et al [3] (in order to produce 
a grid-rounded glyph polygon intersection in a single scanline pass)

It's very stable- at www.scribd.com, it's used to process (intersect) 
over 150,000,000 polygons (stemming from figures and illustrations
in documents) every single day.


[1] http://ect.bell-labs.com/who/hobby/93_2-27.pdf),
[2] http://www.springerlink.com/content/p46t8502v6q6g687/
[3] http://cccg.ca/proceedings/2007/07a1full.pdf