On my website, http://esprit.campus.luth.se/~humus/ , there’s a file called Framework.zip, download it and find the Polygon.cpp file. In there I have code which cuts Polygons against a plane. I suppose it could be useful for you.
[This message has been edited by Humus (edited 10-19-2003).]
Have you tried looking on the web for articles on Sutherland-Hodgeman clipping? This is a common method used to clip polygons against a plane and is fairly easy to code.
Polygon *front;
Polygon *back;
poly_in->split(frstm_planes[0],back,front);
// Now I have two polygons
// What polygon it is necessary to use
// for next plane.
// front or back?
..........