CGAL 5.1.2 - 2D and 3D Linear Geometry Kernel
|
#include <CGAL/Segment_2.h>
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.
Hashable
if Kernel
is a cartesian kernel and if Kernel::FT
is Hashable
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< Kernel > | source () const |
returns the source of s . | |
Point_2< Kernel > | target () const |
returns the target of s . | |
Point_2< Kernel > | min () const |
returns the point of s with lexicographically smallest coordinate. | |
Point_2< Kernel > | max () const |
returns the point of s with lexicographically largest coordinate. | |
Point_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 . More... | |
Point_2< Kernel > | point (int i) const |
returns vertex(i) . | |
Point_2< Kernel > | operator[] (int i) const |
returns vertex(i) . | |
Kernel::FT | squared_length () const |
returns the squared length of s . | |
Direction_2< Kernel > | direction () const |
returns the direction from source to target of s . | |
Vector_2< Kernel > | to_vector () const |
returns the vector s.target() - s.source() . | |
Segment_2< Kernel > | opposite () const |
returns a segment with source and target point interchanged. | |
Line_2< Kernel > | supporting_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< Kernel > | transform (const Aff_transformation_2< Kernel > &t) const |
returns the segment obtained by applying t on the source and the target of s . | |
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.
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()
.
p
is on the supporting line of s
. 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
.
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.