CGAL::Weighted_point_2< Kernel > Class Template Reference

#include <CGAL/Weighted_point_2.h>

Definition

An object of the class Weighted_point_2 is a tuple of a two-dimensional point and a scalar weight.

Remember that Kernel::RT and Kernel::FT denote a RingNumberType and a FieldNumberType, respectively. For the kernel model Cartesian<NT>, the two types are the same. For the kernel model Homogeneous<NT>, Kernel::RT is equal to NT, and Kernel::FT is equal to Quotient<NT>.

See also

Point_2<Kernel>

Is Model Of:

Kernel::WeightedPoint_2

Hashable if Kernel is a cartesian kernel and if Kernel::FT is Hashable

Types
typedef unspecified_type	Cartesian_const_iterator
	An iterator for enumerating the Cartesian coordinates of a point.

Creation
Constructors from coordinates are provided for convenience, except that they are only from Cartesian coordinates, and with no weight, so as to avoid any potential ambiguity between the homogeneous weight and the power weight (it should be easy enough to pass a Point_2 explicitly in those cases).
	Weighted_point_2 (const Origin &ORIGIN)
	introduces a weighted point with Cartesian coordinates (0,0) and weight 0.
	Weighted_point_2 (const Point_2< Kernel > &p)
	introduces a weighted point from point p and weight 0. More...
	Weighted_point_2 (const Point_2< Kernel > &p, Kernel::FT &w)
	introduces a weighted point from point p and weight w.
	Weighted_point_2 (const Kernel::FT &x, const Kernel::FT &y)
	introduces a weighted point with coordinates x, y, and weight 0.

Bare point and weight accessors
Point_2< Kernel >	point () const
	returns the point of the weighted point.
Kernel::FT	weight () const
	returns the weight of the weighted point.

Operations
Warning Comparison and equality operators (==, !=, <, etc.) currently operate directly on the underlying bare point. Consequently: Point_2< Cartesian<double> > p(1.0, 2.0); Weighted_point_2< Cartesian<double> > wp(p, 1.0), wq(p, 2.0); // same bare point, but different weights wp == wq; // is equal to `true`
bool	operator== (const Weighted_point_2< Kernel > &q) const
	Test for equality. More...
bool	operator!= (const Weighted_point_2< Kernel > &q) const
	Test for inequality. More...

Coordinate Access
There are two sets of coordinate access functions, namely to the homogeneous and to the Cartesian coordinates. They can be used independently from the chosen kernel model. Note that you do not lose information with the homogeneous representation, because the FieldNumberType is a quotient.
Kernel::RT	hx () const
	returns the homogeneous \( x\) coordinate.
Kernel::RT	hy () const
	returns the homogeneous \( y\) coordinate.
Kernel::RT	hw () const
	returns the homogenizing coordinate.
Kernel::FT	x () const
	returns the Cartesian \( x\) coordinate, that is hx()/hw().
Kernel::FT	y () const
	returns the Cartesian \( y\) coordinate, that is hy()/hw().

Convenience Operations
The following operations are for convenience and for compatibility with higher dimensional points. Again they come in a Cartesian and in a homogeneous flavor.
Kernel::RT	homogeneous (int i) const
	returns the i'th homogeneous coordinate of p. More...
Kernel::FT	cartesian (int i) const
	returns the i'th Cartesian coordinate of p. More...
Kernel::FT	operator[] (int i) const
	returns cartesian(i). More...
Cartesian_const_iterator	cartesian_begin () const
	returns an iterator to the Cartesian coordinates of p, starting with the 0th coordinate.
Cartesian_const_iterator	cartesian_end () const
	returns an off the end iterator to the Cartesian coordinates of p.
int	dimension () const
	returns the dimension (the constant 2).
Bbox_2	bbox () const
	returns a bounding box containing p.
Weighted_point_2< Kernel >	transform (const Aff_transformation_2< Kernel > &t) const
	returns the weighted point obtained by applying t on p.

Constructor & Destructor Documentation

Weighted_point_2()

template<typename Kernel >

CGAL::Weighted_point_2< Kernel >::Weighted_point_2 ( const Point_2< Kernel > &  p )

explicit

introduces a weighted point from point p and weight 0.

Warning

The explicit keyword is used to avoid accidental implicit conversions between Point_2 and Weighted_point_2.

Member Function Documentation

cartesian()

template<typename Kernel >

Kernel::FT CGAL::Weighted_point_2< Kernel >::cartesian

(

int

i

)

const

returns the i'th Cartesian coordinate of p.

Precondition

\( 0\leq i \leq1\).

homogeneous()

template<typename Kernel >

Kernel::RT CGAL::Weighted_point_2< Kernel >::homogeneous

(

int

i

)

const

returns the i'th homogeneous coordinate of p.

Precondition

\( 0\leq i \leq2\).

operator!=()

template<typename Kernel >

bool CGAL::Weighted_point_2< Kernel >::operator!=

(

const Weighted_point_2< Kernel > &

q

)

const

Test for inequality.

The point can be compared with ORIGIN.

operator==()

template<typename Kernel >

bool CGAL::Weighted_point_2< Kernel >::operator==

(

const Weighted_point_2< Kernel > &

q

)

const

Test for equality.

Two points are equal, iff their \( x\) and \( y\) coordinates are equal. The point can be compared with ORIGIN.

operator[]()

template<typename Kernel >

Kernel::FT CGAL::Weighted_point_2< Kernel >::operator[]

(

int

i

)

const

returns cartesian(i).

Precondition

\( 0\leq i \leq1\).