Polygon-plane intersection algorithm

Hi,

I would like to compute a 3d polygon-plane intersection or more generally a polygon-polygon intersection. My goal is to be able to retrieve a set of segments to draw the contour at a given Z value.

I found some mathematical foundations here [1] and wonder if some of you have/know a good implementation of such kind of algorithm in java.

Thanks in advance,

Martin

[1] http://geomalgorithms.com/a06-_intersect-2.html