\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)
CGAL 4.4 - 2D and 3D Linear Geometry Kernel
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CGAL::Segment_2< Kernel > Class Template Reference

#include <CGAL/Segment_2.h>

Definition

An object s of the data type Segment_2 is a directed straight line segment in the two-dimensional Euclidean plane \( \E^2\), i.e. a straight line segment \( [p,q]\) connecting two points \( p,q \in \mathbb{R}^2\).

The segment is topologically closed, i.e. the end points belong to it. Point p is called the source and q is called the target of s. The length of s is the Euclidean distance between p and q. Note that there is only a function to compute the square of the length, because otherwise we had to perform a square root operation which is not defined for all number types, which is expensive, and may not be exact.

See Also
Kernel::Segment_2

Creation

 Segment_2 (const Point_2< Kernel > &p, const Point_2< Kernel > &q)
 introduces a segment s with source p and target q. More...
 

Operations

bool operator== (const Segment_2< Kernel > &q) const
 Test for equality: Two segments are equal, iff their sources and targets are equal.
 
bool operator!= (const Segment_2< Kernel > &q) const
 Test for inequality.
 
Point_2< Kernelsource () const
 returns the source of s.
 
Point_2< Kerneltarget () const
 returns the target of s.
 
Point_2< Kernelmin () const
 returns the point of s with lexicographically smallest coordinate.
 
Point_2< Kernelmax () const
 returns the point of s with lexicographically largest coordinate.
 
Point_2< Kernelvertex (int i) const
 returns source or target of s: vertex(0) returns the source of s, vertex(1) returns the target of s. More...
 
Point_2< Kernelpoint (int i) const
 returns vertex(i).
 
Point_2< Kerneloperator[] (int i) const
 returns vertex(i).
 
Kernel::FT squared_length () const
 returns the squared length of s.
 
Direction_2< Kerneldirection () const
 returns the direction from source to target of s.
 
Vector_2< Kernelto_vector () const
 returns the vector s.target() - s.source().
 
Segment_2< Kernelopposite () const
 returns a segment with source and target point interchanged.
 
Line_2< Kernelsupporting_line () const
 returns the line l passing through s. More...
 

Predicates

bool is_degenerate () const
 segment s is degenerate, if source and target are equal.
 
bool is_horizontal () const
 
bool is_vertical () const
 
bool has_on (const Point_2< Kernel > &p) const
 A point is on s, iff it is equal to the source or target of s, or if it is in the interior of s.
 
bool collinear_has_on (const Point_2< Kernel > &p) const
 checks if point p is on segment s. More...
 

Miscellaneous

Bbox_2 bbox () const
 returns a bounding box containing s.
 
Segment_2< Kerneltransform (const Aff_transformation_2< Kernel > &t) const
 returns the segment obtained by applying t on the source and the target of s.
 

Constructor & Destructor Documentation

template<typename Kernel >
CGAL::Segment_2< Kernel >::Segment_2 ( const Point_2< Kernel > &  p,
const Point_2< Kernel > &  q 
)

introduces a segment s with source p and target q.

The segment is directed from the source towards the target.

Member Function Documentation

template<typename Kernel >
bool CGAL::Segment_2< Kernel >::collinear_has_on ( const Point_2< Kernel > &  p) const

checks if point p is on segment s.

This function is faster than function has_on().

Precondition
p is on the supporting line of s.
template<typename Kernel >
Line_2<Kernel> CGAL::Segment_2< Kernel >::supporting_line ( ) const

returns the line l passing through s.

Line l has the same orientation as segment s.

template<typename Kernel >
Point_2<Kernel> CGAL::Segment_2< Kernel >::vertex ( int  i) const

returns source or target of s: vertex(0) returns the source of s, vertex(1) returns the target of s.

The parameter i is taken modulo 2, which gives easy access to the other vertex.