>I m looking for a source code coded either in Pascal or C (C++) for the >Weiler-Atherton algorithm. The page http://members.xoom.com/msleonov/pbcomp.html has a comparison of many packages for boolean operations on polygons. Links

The Clipper library performs clipping and offsetting for both lines and polygons. All four boolean clipping operations are supported - intersection, union, difference and exclusive-or. Polygons can be of any shape including self-intersecting polygons