CGAL users discussion list

[Nicklas SB Karlsson <>]

Solved using:
  typedef CGAL::Exact_predicates_exact_constructions_kernel Kernel;
  typedef CGAL::Gps_circle_segment_traits_2<Kernel>         Traits_2;
  typedef Traits_2::Point_2                                 Traits_2_Point_2;

  typedef std::pair<Traits_2_Point_2, unsigned int> pair_type;
  typedef boost::variant<pair_type, X_monotone_curve_2> variant_type;

  const X_monotone_curve_2 stockSegment = input; // from polygon boundary
  std::list<variant_type> pts;
  intersector(segment, stockSegment, std::back_inserter(pts));

  for(auto itD : pts)
  {
      const variant_type variant = itD;
      if(variant.type() == typeid(pair_type))
      {
          const pair_type paret = boost::get<pair_type>(variant);
          Traits_2_Point_2 point = paret.first;

          intersections.push_back(point);
      }
      //const X_monotone_curve_2 x = boost::get<X_monotone_curve_2>(variant);
  }
I am able to calculate intersection between X_monotone_curve_2_from general 
polygon boundary. Or more exact intersection
points between general polygon boundaries.

Performance I am however not very happy wiht, one thousand iterations almost 
80 seconds. Might be because data is stored
in std::list and plenty of dynamic memory allocation is needed for each 
iteration and also because number of
X_monotone_curve_2 grow linearly with number of iterations which I have to do 
something about in my implementation.


Nicklas Karlsson


sön 2024-01-21 klockan 17:06 +0100 skrev Nicklas SB Karlsson:
> Try to calculate intersection points between polygon outer boundaries. Are 
> able to iterate thru the curves and get
> them
> as X_monotone_Cruve_2 or more exact:
>   typedef CGAL::Exact_predicates_exact_constructions_kernel Kernel;
>   typedef CGAL::Gps_circle_segment_traits_2<Kernel>         Traits_2;
>   typedef Traits_2::X_monotone_curve_2                      
> X_monotone_curve_2;
> 
> Are also able to create an intersector with:
>   CGAL::Arr_circle_segment_traits_2<Kernel> t2;
>   auto intersector = t2.intersect_2_object();
> 
> Then trying to use the intersector with:
>   std::list<Apoint_2> pts
>   CGAL::intersection(intsegments.begin(), intsegments.end(), 
> std::back_inserter(pts));
> I however get a compiler error about the iterator. Tried diferent types for 
> the point:
>   typedef Kernel::Point_2                                   K_Point_2;  
>   typedef Traits_2::Point_2                                 Apoint_2;
>   typedef Polygon_2::Point_2                                P_Point_2;
> But all without success. Anybody have a clue what might be wrong?
> 
> Nicklas Karlsson
> 
>