 CGAL 4.7 - 2D and 3D Linear Geometry Kernel
CGAL::Ray_2< Kernel > Class Template Reference

#include <CGAL/Ray_2.h>

## Definition

An object r of the data type Ray_2 is a directed straight ray in the two-dimensional Euclidean plane $$\E^2$$.

It starts in a point called the source of r and goes to infinity.

Kernel::Ray_2

## Creation

Ray_2 (const Point_2< Kernel > &p, const Point_2< Kernel > &q)
introduces a ray r with source p and passing through point q.

Ray_2 (const Point_2< Kernel > &p, const Direction_2< Kernel > &d)
introduces a ray r starting at source p with direction d.

Ray_2 (const Point_2< Kernel > &p, const Vector_2< Kernel > &v)
introduces a ray r starting at source p with the direction of v.

Ray_2 (const Point_2< Kernel > &p, const Line_2< Kernel > &l)
introduces a ray r starting at source p with the same direction as l.

## Operations

bool operator== (const Ray_2< Kernel > &h) const
Test for equality: two rays are equal, iff they have the same source and the same direction.

bool operator!= (const Ray_2< Kernel > &h) const
Test for inequality.

Point_2< Kernelsource () const
returns the source of r.

Point_2< Kernelpoint (int i) const
returns a point on r. More...

Direction_2< Kerneldirection () const
returns the direction of r.

Vector_2< Kernelto_vector () const
returns a vector giving the direction of r.

Line_2< Kernelsupporting_line () const
returns the line supporting r which has the same direction.

Ray_2< Kernelopposite () const
returns the ray with the same source and the opposite direction.

## Predicates

bool is_degenerate () const
ray r is degenerate, if the source and the second defining point fall together (that is if the direction is degenerate).

bool is_horizontal () const

bool is_vertical () const

bool has_on (const Point_2< Kernel > &p) const
A point is on r, iff it is equal to the source of r, or if it is in the interior of r.

bool collinear_has_on (const Point_2< Kernel > &p) const
checks if point p is on r. More...

## Miscellaneous

Ray_2< Kerneltransform (const Aff_transformation_2< Kernel > &t) const
returns the ray obtained by applying t on the source and on the direction of r.

## Member Function Documentation

template<typename Kernel >
 bool CGAL::Ray_2< Kernel >::collinear_has_on ( const Point_2< Kernel > & p) const

checks if point p is on r.

This function is faster than function has_on() if the precondition checking is disabled.

Precondition
p is on the supporting line of r.
template<typename Kernel >
 Point_2 CGAL::Ray_2< Kernel >::point ( int i) const

returns a point on r.

point(0) is the source, point(i), with i>0, is different from the source.

Precondition
$$i \geq0$$.