CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

The first thing to try is to replace

typedef CGAL::Cartesian<Number_type> Kernel;
by
typedef CGAL::Exact_predicates_exact_constructions_kernel Kernel;

Sebastien.

On 07/23/2013 08:47 PM, Willy Lambert wrote:
> Hi all,
>
> I'm quite new to cgal, and I'm trying to use it in robotics path
> planning. To do so I create a polygon with holes which show reachable
> areas. I initiate a polygon set with the "outer" map and then do a
> difference with each obstacles thougth eating borders of the map or
> creating an hole.
>
> It is working for many obstacles except one, which is asserting when I
> do the difference. I didn't used cgal enougth to be able to find if it
> is a cgal bug or a mis-use so I'm asking some help here to clarify this.
>
> Here is a simple code to reproduce :
>
> typedef float Number_type;
> typedef CGAL::Cartesian<Number_type> Kernel;
> typedef Kernel::Point_2 Point_2;
> typedef CGAL::Polygon_2<Kernel> Polygon_2;
> typedef CGAL::Polygon_with_holes_2<Kernel> Polygon_with_holes_2;
> typedef CGAL::Polygon_set_2<Kernel> Polygon_set_2;
>
> Polygon_2 A,B;
>
> A.push_back(Point_2(1350, -850));
> A.push_back(Point_2(1350, 850));
> A.push_back(Point_2(-1350, -850));
>
> B.push_back(Point_2(1003, -116));
> B.push_back(Point_2(947, -251));
> B.push_back(Point_2(984, -1000));
>
> Polygon_set_2 S;
> S.insert(A);
> S.difference(B);
>
>
> It compiles and throw at execution :
>
> (atlantronic) robot@ard-host ~/workspace/test_cgal/Debug $ ./test_cgal
> terminate called after throwing an instance of
> 'CGAL::Precondition_exception'
>    what():  CGAL ERROR: precondition violation!
> Expr: comp_f(object, parentP->object) != SMALLER
> File: /home/robot/workspace/CGAL-4.2/include/CGAL/Multiset.h
> Line: 2129
> Aborted (core dumped)
>
> Here is a screen shot if it can help visualizing  the problem.
> http://cgal-discuss.949826.n4.nabble.com/file/n4657830/cgal_problem.png
>
>
> Let me know if you need any further information or if I need to
> re-formulate my demand which standard debug information set.
>
> Regards.