## CGAL::Nef_polyhedron_S2<Traits>::SHalfloop

### Definition

A sloop is a great circle on a sphere. A shalfloop is an oriented sloop. It is always paired with a shalfloop whose supporting Sphere_circle is pointing in the opposite direction. The twin() member function returns this shalfloop of opposite orientation. Each Nef_polyhedron_S2 can only have one sloop (resp. two shalfloops).

The figure below depicts the relationship between a shalfloop and sfaces on a sphere map.

Figure:

#include <CGAL/Nef_polyhedron_S2.h>

### Types

The following types are the same as in Nef_polyhedron_S2<Traits>.

Nef_polyhedron_S2<Traits>::SHalfloop::Mark
| type of mark.
Nef_polyhedron_S2<Traits>::SHalfloop::Sphere_circle
| sphere circle type stored in SHalfloop.
Nef_polyhedron_S2<Traits>::SHalfloop::SHalfloop_const_handle
| const handle to SHalfloop.
Nef_polyhedron_S2<Traits>::SHalfloop::SFace_const_handle
| const handle to SFace.

### Creation

There is no need for a user to create a SHalfloop explicitly. The class Nef_polyhedron_S2<Traits> manages the needed shalfloops internally.

### Operations

Mark | se.mark () | the mark of se .
Sphere_circle | se.circle () | the sphere circle of se .
SHalfloop_const_handle
| se.twin () | the twin of se .
SFace_const_handle | se.incident_sface ()
|  | the incident sface of se .

### See Also

CGAL::Nef_polyhedron_S2<Traits>::SFace
CGAL::Nef_polyhedron_S2<Traits>::Sphere_circle