CGAL::HalfedgeDS_items_2 Class Reference

#include <CGAL/HalfedgeDS_items_2.h>

Definition

The class HalfedgeDS_items_2 is a model of the HalfedgeDSItems concept.

It uses the default types for vertices, halfedges, and faces that declare all incidences supported by a HalfedgeDS. The vertex also contains a point of type Traits::Point_2, where Traits is the template argument of the corresponding HalfedgeDS.

Is Model Of:

HalfedgeDSItems

See also

CGAL::HalfedgeDS_min_items

CGAL::Polyhedron_items_3

HalfedgeDS<Traits,Items,Alloc>

PolyhedronItems_3

CGAL::HalfedgeDS_vertex_base<Refs>

CGAL::HalfedgeDS_halfedge_base<Refs>

CGAL::HalfedgeDS_face_base<Refs>

Example

The following example shows the canonical implementation of the HalfedgeDS_items_2 class. It uses the base classes for the item types that are provided in the library.

struct HalfedgeDS_items_2 {
template < class Refs, class Traits>
struct Vertex_wrapper {
typedef typename Traits::Point_2 Point;
typedef CGAL::HalfedgeDS_vertex_base< Refs, Tag_true, Point> Vertex;
};
template < class Refs, class Traits>
struct Halfedge_wrapper {
typedef CGAL::HalfedgeDS_halfedge_base< Refs> Halfedge;
};
template < class Refs, class Traits>
struct Face_wrapper {
typedef CGAL::HalfedgeDS_face_base< Refs> Face;
};
};

The following example shows a class definition for a new items class derived from the HalfedgeDS_items_2 class. It replaces the Face_wrapper with a new definition of a face that contains a member variable for color. The new face makes use of the face base class provided in the library.

// A face type with a color member variable.
template <class Refs>
struct My_face : public CGAL::HalfedgeDS_face_base<Refs> {
CGAL::IO::Color color;
My_face() {}
My_face( CGAL::IO::Color c) : color(c) {}
};

// An items type using my face.
struct My_items : public CGAL::HalfedgeDS_items_2 {
template <class Refs, class Traits>
struct Face_wrapper {
typedef My_face<Refs> Face;
};
};

Examples:

HalfedgeDS/hds_prog_color.cpp, HalfedgeDS/hds_prog_compact.cpp, and HalfedgeDS/hds_prog_compact2.cpp.