CGAL users discussion list

["Gernot H. Gutschi" <>]

Hi!

Which kernel are you using? You have to use an exact constructions kernel for intersections.

Ng
Gernot

Am 19.07.2011 11:47 schrieb "Gillian Ng" <>:
> I'm just trying to find out if two polygons intersect. However it gives this
> error, which seems odd... I'm using CGAL 3.6.1 with Visual Studio .NET 2005.
>
> ----------
> CGAL error: precondition violation!
> _expression_ : ! _predP->is_valid() || comp_f(object, _predP->object) !=
> SMALLER
> File : d:\libs\cgal_vc8\include\cgal\multiset.h
> Line : 2142
> Explanation:
> Refer to the bug-reporting instructions at
> http://www.cgal.org/bug_report.html
> ----------
>
> This is the code I wrote:
>
> ----------
> typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
> typedef CGAL::Polygon_2 <K> Polygon_2;
>
> bool DoPolygonsIntersect( Polygon_2 &p1, Polygon_2 &p2 )
> {
> if ( CGAL::do_overlap( p1.bbox(), p2.bbox() ) )
> {
> if ( CGAL::do_intersect( p1, p2 ) )
> {
> return true;
> }
> }
>
> return false;
> }
> ----------
>
> Please help! Thanks a lot guys.
>
> --
> View this message in context: http://cgal-discuss.949826.n4.nabble.com/CGAL-polygon-intersection-predicate-precondition-exception-tp3677725p3677725.html
> Sent from the cgal-discuss mailing list archive at Nabble.com.
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to
> https://lists-sop.inria.fr/wws/info/cgal-discuss
>