CGAL 6.0  2D Arrangements

#include <CGAL/Arrangement_on_surface_2.h>
typename Dcel::Halfedge.
An object \( e\) of the class Halfedge
represents a halfedge in the arrangement.
A halfedge is directed from its source vertex to its target vertex, and has an incident face lying to its left. Each halfedge has a twin halfedge directed in the opposite direction, where the pair of twin halfedges form together an arrangement edge, that is, a \( 1\)dimensional cell, associated with planar \( x\)monotone curve.
Halfedges are stored in doublyconnected lists and form chains. These chains define the inner and outer boundaries of connected components.
Creation  
Halfedge ()  
default constructor.  
Access Functions  
All nonconst methods listed below also have  
bool  is_fictitious () const 
determines whether the halfedge is fictitious (i.e., connects two vertices at infinity and is not associated with a valid curve).  
Vertex_handle  source () 
obtains a handle for the source vertex of e .  
Vertex_handle  target () 
obtains a handle for the target vertex of e .  
Arr_halfedge_direction  direction () const 
obtains the direction of the halfedge: ARR_LEFT_TO_RIGHT if e 's source vertex is lexicographically smaller than it target (so the halfedge is directed from left to right), and ARR_RIGHT_TO_LEFT if it is lexicographically larger than the target (so the halfedge is directed from right to left).  
Face_handle  face () 
obtains the face that e is incident to (The face lies to the left of e ).  
Halfedge_handle  twin () 
obtains the twin halfedge.  
Halfedge_handle  prev () 
obtains e 's predecessor in the connected component it belongs to.  
Halfedge_handle  next () 
obtains e 's successor in the connected component it belongs to.  
Ccb_halfedge_circulator  ccb () 
obtains a circulator that allows traversing the halfedges of the connected component boundary (CCB) that contains e .  
const Traits::X_monotone_curve_2 &  curve () const 
obtains the \( x\)monotone curve associated with e .  
Ccb_halfedge_circulator CGAL::Arrangement_on_surface_2< GeometryTraits, TopologyTraits >::Halfedge::ccb  (  ) 
obtains a circulator that allows traversing the halfedges of the connected component boundary (CCB) that contains e
.
The circulator is initialized to point to e
.
const Traits::X_monotone_curve_2 & CGAL::Arrangement_on_surface_2< GeometryTraits, TopologyTraits >::Halfedge::curve  (  )  const 
obtains the \( x\)monotone curve associated with e
.
e
is not a fictitious halfedge.