CGAL users discussion list

[Thomas Zangl <>]

 wrote:
>> How to convert a K::Ray_2 to a Circular_k::Line_arc_2?
>
> It cannot work: rays go to infinity, while 'line arcs' have two finite
> (possibly algebraic) endpoints.
You are right and the clipping of the ray makes them finite but, I was
also unable to convert a segment to a Line_Arc_2. I worked-a-round using
the << and >> operators and a tempfile (for debugging).
But this is inefficient and ugly :-)

This is my work-a-round code, maybe you can show my the right way to
cast the Segment into Line_Arc_2:

[...]
typedef CGAL::Filtered_kernel<SC> K;
typedef K::Ray_2 Ray;
typedef K::Line_2 Line;
typedef K::Point_2 Point_base;
typedef K::Segment_2  Segment;
typedef CGAL::Exact_circular_kernel_2                   Circular_k;
typedef Circular_k::Circle_2                            Circle_2;
typedef Circular_k::Point_2                             SimplePoint_2;
typedef Circular_k::Circular_arc_point_2                ArcPoint_2;
typedef Circular_k::Line_arc_2                          Line_arc_2;
typedef Line_arc_2  LineArc;
typedef std::vector< Circle_2> ArcContainer;
typedef std::vector< LineArc> LineContainer;
typedef std::vector< ArcPoint_2> PointContainer;

[...]
//---------------------------------------------------------------------
void getIntersectionsSegment(Segment s, PointContainer& intersections,
ArcContainer& ac) {
  std::ofstream os("data/data_tmp", std::ios::out);
  os << s;
  os.close();

  std::ifstream iEdges("data/data_tmp",std::ios::in);
  SimplePoint_2 p1;
  SimplePoint_2 p2;
  if (!iEdges) {
    std::cout << "Cannot open temp file" << std::endl;
    return;
  }
  iEdges >> p1;
  iEdges >> p2;

  std::cout << "XY: " << p1 << "/" << p2 << endl;
  Circular_k::Line_arc_2
circularSegment(Line_arc_2(Circular_k::Line_2(p1, p2),
Circular_k::Circular_arc_point_2(p1),
Circular_k::Circular_arc_point_2(p2)));
....
}

Thanks! :-)

Thomas