## CGAL::Nef_polyhedron_S2<Traits>::Sphere_point

### Definition

An object p of type Sphere_point<R> is a point on the surface of a unit sphere. Such points correspond to the nontrivial directions in space and similarly to the equivalence classes of all nontrivial vectors under normalization.

### Types

Nef_polyhedron_S2<Traits>::Sphere_point::RT
| ring number type.

### Creation

Nef_polyhedron_S2<Traits>::Sphere_point p;
| creates some sphere point.
Nef_polyhedron_S2<Traits>::Sphere_point p ( RT x, RT y, RT z);
| creates a sphere point corresponding to the point of intersection of the ray starting at the origin in direction (x,y,z) and the surface of S2.

### Operations

Access to the coordinates is provided by the following operations. Note that the vector (x,y,z) is not normalized.

RT | p.x () | the x-coordinate.
RT | p.y () | the y-coordinate.
RT | p.z () | the z-coordinate.
bool | p == Sphere_point q
|  | Equality.
bool | p != Sphere_point q
|  | Inequality.
Sphere_point | p.antipode () | returns the antipode of p.