frechet::poly::Segment Class Reference

Detailed Description

Represents a polygon line segment from node i to j.

Note that polygon edges are meant to be oriented, i.e. j==i+1 The last edge back to the starting point is therefore encoded as (n-1,n) (instead of (n-1,0)). The equation j==i+1 indicates proper polygon edges and indices should be taken modulo n.

However. For diagonals, orientation is not encoded, therefore i < j so that we can sort and identify diagonals.

If this seems confusing, we should think about introducing two data types, (one for edges, another one for diagonals), or introduce a flag for edges.

Author

Peter Schäfer

Definition at line 39 of file types.h.

#include <types.h>

Inherits pair< int, int >.

Public Member Functions
	Segment ()
	empty constructor; creates an invalid polygon segment More...
	Segment (int i, int j)
	default constructor with vertices. For poylgon edge segments, j==i+1 or j+1==i is expected. For diagonal segements, j!=i+1. More...
bool	empty () const
bool	is_diagonal (int n) const
bool	is_edge (int n) const
bool	operator< (const Segment &that) const
	ordering operator. Imposes a natural ordering on segments, which is useful for sorting sets of segments. More...
QLineF	map (const Curve &curve) const
	map (embed) segment to a line in the plane More...

Static Public Member Functions
static QPointF	map (const Curve &curve, int i)
	map a polygon vertex to a point in the plane More...

Constructor & Destructor Documentation

Segment() [1/2]

frechet::poly::Segment::Segment ( )

inline

empty constructor; creates an invalid polygon segment

Definition at line 45 of file types.h.

Segment() [2/2]

frechet::poly::Segment::Segment ( int  i, int  j  )

inline

default constructor with vertices. For poylgon edge segments, j==i+1 or j+1==i is expected. For diagonal segements, j!=i+1.

Parameters

i	first vertex
j	second vertex

Definition at line 53 of file types.h.

Member Function Documentation

empty()

bool frechet::poly::Segment::empty ( ) const

inline

Returns

true if the segment is empty, or invalid

Definition at line 62 of file types.h.

is_diagonal()

bool frechet::poly::Segment::is_diagonal ( int  n ) const

inline

Parameters

n	number of vertices in polygon

Returns

true if this segment describes a polygon diagonal

Definition at line 69 of file types.h.

is_edge()

bool frechet::poly::Segment::is_edge ( int  n ) const

inline

Parameters

n	number of vertices in polygon

Returns

true if this segment describes a polygon egde segment

Definition at line 76 of file types.h.

map() [1/2]

QLineF frechet::poly::Segment::map ( const Curve &  curve ) const

inline

map (embed) segment to a line in the plane

Parameters

curve

a polygonal curve

Returns

segment embedded in the plane

Definition at line 98 of file types.h.

map() [2/2]

static QPointF frechet::poly::Segment::map ( const Curve &  curve, int  i  )

inlinestatic

map a polygon vertex to a point in the plane

Parameters

curve	a polygonal curve
i	index of vertex (modulo n)

Returns

point in the plane

Definition at line 107 of file types.h.

operator<()

bool frechet::poly::Segment::operator< ( const Segment &  that ) const

inline

ordering operator. Imposes a natural ordering on segments, which is useful for sorting sets of segments.

Parameters

that	segment to compare with

Returns

true if *this < that

Definition at line 86 of file types.h.

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The documentation for this class was generated from the following file:

• include/frechet/poly/types.h