Triangle-Box Overlap Test [Updated 2004-08-25]
The article is here. Old code is here. New, faster code is here. It's not noticably faster on a 1333 MHz PC,
but it's about 15% faster on a SUN 333MHz. Bug-fixed code This is the code you should get. It correctly
reports intersections for triangles completely in a box plane. Bug fix by Nick Pelling: thanks!