GEOS  3.9.0dev
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geos::triangulate::quadedge::QuadEdge Class Reference

A class that represents the edge data structure which implements the quadedge algebra. More...

#include <QuadEdge.h>

Public Member Functions

const QuadEdgegetPrimary ()
 Gets the primary edge of this quadedge and its sym. More...
 
void remove ()
 Marks this quadedge as being deleted. More...
 
bool isLive () const
 Tests whether this edge has been deleted. More...
 
bool isVisited () const
 
void setVisited (bool v)
 
void setNext (QuadEdge *p_next)
 Sets the connected edge. More...
 
const QuadEdgerot () const
 Gets the dual of this edge, directed from its right to its left. More...
 
QuadEdgerot ()
 
const QuadEdgeinvRot () const
 Gets the dual of this edge, directed from its left to its right. More...
 
QuadEdgeinvRot ()
 
const QuadEdgesym () const
 Gets the edge from the destination to the origin of this edge. More...
 
QuadEdgesym ()
 
const QuadEdgeoNext () const
 Gets the next CCW edge around the origin of this edge. More...
 
QuadEdgeoNext ()
 
const QuadEdgeoPrev () const
 Gets the next CW edge around (from) the origin of this edge. More...
 
QuadEdgeoPrev ()
 
const QuadEdgedNext () const
 Gets the next CCW edge around (into) the destination of this edge. More...
 
const QuadEdgedPrev () const
 Gets the next CW edge around (into) the destination of this edge. More...
 
QuadEdgedPrev ()
 
const QuadEdgelNext () const
 Gets the CCW edge around the left face following this edge. More...
 
QuadEdgelNext ()
 
const QuadEdgelPrev () const
 Gets the CCW edge around the left face before this edge. More...
 
QuadEdgelPrev ()
 
const QuadEdgerNext () const
 Gets the edge around the right face ccw following this edge. More...
 
const QuadEdgerPrev () const
 Gets the edge around the right face ccw before this edge. More...
 
void setOrig (const Vertex &o)
 Sets the vertex for this edge's origin. More...
 
void setDest (const Vertex &d)
 Sets the vertex for this edge's destination. More...
 
const Vertexorig () const
 Gets the vertex for the edge's origin. More...
 
const Vertexdest () const
 Gets the vertex for the edge's destination. More...
 
double getLength () const
 Gets the length of the geometry of this quadedge. More...
 
bool equalsNonOriented (const QuadEdge &qe) const
 Tests if this quadedge and another have the same line segment geometry, regardless of orientation. More...
 
bool equalsOriented (const QuadEdge &qe) const
 Tests if this quadedge and another have the same line segment geometry with the same orientation. More...
 
std::unique_ptr
< geom::LineSegment
toLineSegment () const
 Creates a geom::LineSegment representing the geometry of this edge. More...
 

Static Public Member Functions

static QuadEdgemakeEdge (const Vertex &o, const Vertex &d, std::deque< QuadEdgeQuartet > &edges)
 Creates a new QuadEdge quartet from Vertex o to Vertex d. More...
 
static QuadEdgeconnect (QuadEdge &a, QuadEdge &b, std::deque< QuadEdgeQuartet > &edges)
 Creates a new QuadEdge connecting the destination of a to the origin of b, in such a way that all three have the same left face after the connection is complete. More...
 
static void splice (QuadEdge &a, QuadEdge &b)
 Splices two edges together or apart. More...
 
static void swap (QuadEdge &e)
 Turns an edge counterclockwise inside its enclosing quadrilateral. More...
 

Friends

class QuadEdgeQuartet
 

Detailed Description

A class that represents the edge data structure which implements the quadedge algebra.

The quadedge algebra was described in a well-known paper by Guibas and Stolfi, "Primitives for the manipulation of general subdivisions and the computation of Voronoi diagrams", ACM Transactions on Graphics, 4(2), 1985, 75-123.

Each edge object is part of a QuadEdgeQuartet of 4 edges, linked via relative memory addresses. Quadedges in a subdivision are linked together via their next references. The linkage between the quadedge quartets determines the topology of the subdivision.

The edge class does not contain separate information for vertice or faces; a vertex is implicitly defined as a ring of edges (created using the next field).

Author
JTS: David Skea
JTS: Martin Davis
Benjamin Campbell

Member Function Documentation

static QuadEdge* geos::triangulate::quadedge::QuadEdge::connect ( QuadEdge a,
QuadEdge b,
std::deque< QuadEdgeQuartet > &  edges 
)
static

Creates a new QuadEdge connecting the destination of a to the origin of b, in such a way that all three have the same left face after the connection is complete.

Additionally, the data pointers of the new edge are set.

Returns
the new QuadEdge*
const Vertex& geos::triangulate::quadedge::QuadEdge::dest ( ) const
inline

Gets the vertex for the edge's destination.

Returns
the destination vertex
const QuadEdge& geos::triangulate::quadedge::QuadEdge::dNext ( ) const
inline

Gets the next CCW edge around (into) the destination of this edge.

Returns
the next destination edge.

References oNext(), and sym().

const QuadEdge& geos::triangulate::quadedge::QuadEdge::dPrev ( ) const
inline

Gets the next CW edge around (into) the destination of this edge.

Returns
the previous destination edge.

References invRot(), and oNext().

bool geos::triangulate::quadedge::QuadEdge::equalsNonOriented ( const QuadEdge qe) const

Tests if this quadedge and another have the same line segment geometry, regardless of orientation.

Parameters
qea quadege
Returns
true if the quadedges are based on the same line segment regardless of orientation
bool geos::triangulate::quadedge::QuadEdge::equalsOriented ( const QuadEdge qe) const

Tests if this quadedge and another have the same line segment geometry with the same orientation.

Parameters
qea quadege
Returns
true if the quadedges are based on the same line segment
double geos::triangulate::quadedge::QuadEdge::getLength ( ) const
inline

Gets the length of the geometry of this quadedge.

Returns
the length of the quadedge
const QuadEdge& geos::triangulate::quadedge::QuadEdge::getPrimary ( )

Gets the primary edge of this quadedge and its sym.

The primary edge is the one for which the origin and destination coordinates are ordered according to the standard geom::Coordinate ordering

Returns
the primary quadedge
const QuadEdge& geos::triangulate::quadedge::QuadEdge::invRot ( ) const
inline

Gets the dual of this edge, directed from its left to its right.

Returns
the inverse rotated edge.

Referenced by dPrev(), and rNext().

bool geos::triangulate::quadedge::QuadEdge::isLive ( ) const
inline

Tests whether this edge has been deleted.

Returns
true if this edge has not been deleted.
const QuadEdge& geos::triangulate::quadedge::QuadEdge::lNext ( ) const
inline

Gets the CCW edge around the left face following this edge.

Returns
the next left face edge.

References oNext(), and rot().

const QuadEdge& geos::triangulate::quadedge::QuadEdge::lPrev ( ) const
inline

Gets the CCW edge around the left face before this edge.

Returns
the previous left face edge.

References sym().

static QuadEdge* geos::triangulate::quadedge::QuadEdge::makeEdge ( const Vertex o,
const Vertex d,
std::deque< QuadEdgeQuartet > &  edges 
)
static

Creates a new QuadEdge quartet from Vertex o to Vertex d.

Parameters
othe origin Vertex
dthe destination Vertex
edgesa container in which to store the newly created quartet
Returns
the new QuadEdge*,
const QuadEdge& geos::triangulate::quadedge::QuadEdge::oNext ( ) const
inline

Gets the next CCW edge around the origin of this edge.

Returns
the next linked edge.

Referenced by dNext(), dPrev(), lNext(), oPrev(), rNext(), and rPrev().

const QuadEdge& geos::triangulate::quadedge::QuadEdge::oPrev ( ) const
inline

Gets the next CW edge around (from) the origin of this edge.

Returns
the previous edge.

References oNext(), and rot().

const Vertex& geos::triangulate::quadedge::QuadEdge::orig ( ) const
inline

Gets the vertex for the edge's origin.

Returns
the origin vertex
void geos::triangulate::quadedge::QuadEdge::remove ( )

Marks this quadedge as being deleted.

This does not free the memory used by this quadedge quartet, but indicates that this quadedge quartet no longer participates in a subdivision.

Note
called "delete" in JTS
const QuadEdge& geos::triangulate::quadedge::QuadEdge::rNext ( ) const
inline

Gets the edge around the right face ccw following this edge.

Returns
the next right face edge.

References invRot(), and oNext().

const QuadEdge& geos::triangulate::quadedge::QuadEdge::rot ( ) const
inline

Gets the dual of this edge, directed from its right to its left.

Returns
the rotated edge

Referenced by lNext(), and oPrev().

const QuadEdge& geos::triangulate::quadedge::QuadEdge::rPrev ( ) const
inline

Gets the edge around the right face ccw before this edge.

Returns
the previous right face edge.

References oNext().

void geos::triangulate::quadedge::QuadEdge::setDest ( const Vertex d)
inline

Sets the vertex for this edge's destination.

Parameters
dthe destination vertex
void geos::triangulate::quadedge::QuadEdge::setNext ( QuadEdge p_next)
inline

Sets the connected edge.

Parameters
p_nextedge
void geos::triangulate::quadedge::QuadEdge::setOrig ( const Vertex o)
inline

Sets the vertex for this edge's origin.

Parameters
othe origin vertex
static void geos::triangulate::quadedge::QuadEdge::splice ( QuadEdge a,
QuadEdge b 
)
static

Splices two edges together or apart.

Splice affects the two edge rings around the origins of a and b, and, independently, the two edge rings around the left faces of a and b. In each case, (i) if the two rings are distinct, Splice will combine them into one, or (ii) if the two are the same ring, Splice will break it into two separate pieces. Thus, Splice can be used both to attach the two edges together, and to break them apart.

Parameters
aan edge to splice
ban edge to splice
static void geos::triangulate::quadedge::QuadEdge::swap ( QuadEdge e)
static

Turns an edge counterclockwise inside its enclosing quadrilateral.

Parameters
ethe quadedge to turn
const QuadEdge& geos::triangulate::quadedge::QuadEdge::sym ( ) const
inline

Gets the edge from the destination to the origin of this edge.

Returns
the sym of the edge

Referenced by dNext(), and lPrev().

std::unique_ptr<geom::LineSegment> geos::triangulate::quadedge::QuadEdge::toLineSegment ( ) const

Creates a geom::LineSegment representing the geometry of this edge.

Returns
a LineSegment

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