CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

I think it's the third time in a week that I recommend to read
this FAQ entry:

http://www.cgal.org/FAQ.html#inexact_NT

Replace Exact_predicates_inexact_constructions_kernel
by Exact_predicates_exact_constructions_kernel.

You could expect that since endpoints are equal they are correctly
detected but the implementation is using the intersection point
of supporting line which leads to the wrong result you observe.

Sebastien.

On 03/04/2012 01:24 PM, pgiitu wrote:
> #include<CGAL/Exact_predicates_inexact_constructions_kernel.h>
> #include<CGAL/Polygon_2.h>
> #include<CGAL/Boolean_set_operations_2.h>
> #include<CGAL/Object.h>
>
>
> typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
> typedef K::Point_2 Point;
> typedef CGAL::Polygon_2<K>  Polygon;
> typedef CGAL::Object Object;
> typedef CGAL::Segment_2<K>  Segment;
>
> using namespace std;
> int main(int argc, char ** argv)
> {
>
>         //initialising the segment1
>         Point p11(-3.8,2);
>         Point p12(-3,0);
>         Segment halfedge(p11,p12);
>
>         // initialising a segment1
>         Point source(-5,5);
>         Point target(-3,0);
>         Segment s(source,target);
>
>         //intersection of two segments
>         Object obj=CGAL::intersection(halfedge,s);
>         Point intPoint;
>         Segment intSegment;
>         if(CGAL::assign(intPoint,obj))
>         {
>                         cout<<"  Intersection point:-"<<intPoint<<"\n\n";
>         }
>         else if(CGAL::assign(intSegment,obj))
>         {
>                         cout<<"   Intersection edge"<<intSegment<<"\n\n";
>         }
> }