CGAL users discussion list

[Jasmin Formont <>]

hi folks

I'm new to CGAL and I'm having with polygon intersection. I read 2 polygons from a file and create them this way :

//pseudocode

Polygon_2 pgn   //I typedefed this as CGAL::Polygon_2<Kernel>

for each(point pt in file)

     pgn.push_back(Point_2(pt.x, pt.y))    //Point_2 is Kernel::Point_2

When I print these polygons in a file, they are exactly as my input polygons, so I assume my Polygon_2 are well created and correct.

My problem comes when I try to execute CGAL::do_intersect(pgn1, pgn2)

I get this error :

CGAL error : precondition violation!

_expression_ : ! is_degen

File            : C:\Program Files\CGAL-4.0\include\CGAL\Arr_segment_traits_2.h

Line           : 127

Explanation: cannot construct a degenerate segment

I attached the polygons I use (dxf file), they don't have any degenerate segment.

I have this problem with both Exact_predicates_exact_constructions_kernel and Exact_predicates_inexact_constructions_kernel.

I'd appreciate any help

thanks

Jasmin

Attachment: multipgn.dxf
Description: application/dxf