CGAL users discussion list

[marin <>]

Hello,

I have two questions about inserting constraints in
Constrained_triangulation_plus_2 triangulation.

I'm using triangulation defined like this
        typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
        typedef CGAL::Projection_traits_xy_3<K> Gt;
        typedef CGAL::Triangulation_vertex_base_with_info_2<FaceInfo2, Gt> 
Vbb;
        typedef CGAL::Triangulation_hierarchy_vertex_base_2<Vbb> Vb;
        typedef CGAL::Constrained_triangulation_face_base_2<Gt> Fb_base;
        typedef CGAL::Triangulation_face_base_with_info_2<FaceInfo2, Gt, 
Fb_base>
Fb;
        typedef CGAL::Triangulation_data_structure_2<Vb, Fb> TDS;
        typedef CGAL::Exact_predicates_tag Itag;
        typedef CGAL::Constrained_Delaunay_triangulation_2<Gt, TDS, Itag>
Delaunay_base;
        typedef CGAL::Triangulation_hierarchy_2<Delaunay_base> Triangulation;
        typedef CGAL::Constrained_triangulation_plus_2<Triangulation> 
Delaunay;

1. insert_constraint sometimes throws an exception
        I am using function Constraint_id 
CGAL::Constrained_triangulation_plus_2<
Tr >::insert_constraint( PointIterator first, PointIterator last, bool close
= false )
        
        - it throws exception every time if I try to insert the same polyline
twice.
        - sometimes it throws exception inserting not already inserted 
constraints.
        
        Since Constrained_triangulation_plus_2 should support any polylines 
layout
as constraints including those intersecting each other, please I'm wondering
what are preconditions for the Insert_constraint function in order to work
without exception?

2. In reference manual I've found the function Insert_constraints (plural)
that allows inserting many polyline constraints at once using optimized
algorithm with spatial indexes but I haven't found any examples how to use
it. Please if there are some examples available I would be very grateful.
insert_constraints ( ConstraintIterator first, ConstraintIterator last )

Thank you very much for answers.

Best regards,
Marin



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