CGAL users discussion list

[Christopher Mitchell <>]

Thanks for the quick response. The code is sufficiently trivial (ie, a single if (CGAL::do_intersect(poly1, poly2)) { ... }) that I'm not sure it would help. I'm using a simple loop to convert a set of non-CGAL points into a Polygon_2, making sure to not duplicate the starting point, as you can see from the image attached to the first post. My polygons are CGAL::Polygon_2<CGAL_Kernel>, where CGAL_Kernel is CGAL::Exact_predicates_inexact_constructions_kernel. I hope this helps. Thanks!

On Sat, Sep 10, 2016 at 6:25 PM, Efi Fogel <> wrote:

What number type are you using?  Better yet, could you share the code?

On Sep 10, 2016 18:31, "Christopher Mitchell" <> wrote:

I'm attempting to determine if two Polygon_2s overlap in anyway, ie, share any portion of their interiors, including one being entirely contained by the other. In most cases this works, but for a few polygon pairs, do_intersect() returns false unexpectedly. I make sure (1) all polygons are simple (2) all polygons are not oriented CGAL::CLOCKWISE (I call .reverse_orientation() on the polys if they are CGAL::CLOCKWISE), and (3) that the starting vertex is not duplicated. I have attached an example of a polygon pair for which do_intersect() returns false. Thanks in advance for any insight; I'd be happy to provide additional information as necessary.