csg.js

Source code: http://github.com/evanw/csg.js/
Documentation: http://evanw.github.com/csg.js/docs/

Coplanar Test Cases

These tests cover all the cases of a pair of overlapping coplanar polygons in both solids. To avoid duplicate polygons, the overlapping polygons are kept in the first solid and removed from the second solid.

a
b
a.inverse()
b.inverse()
a.union(b)
b.union(a)
a.subtract(b)
b.subtract(a)
a.intersect(b)
b.intersect(a)
c
d
c.inverse()
d.inverse()
c.union(d)
d.union(c)
c.subtract(d)
d.subtract(c)
c.intersect(d)
d.intersect(c)