GEOS  3.9.0dev
Public Member Functions | Static Public Member Functions | List of all members
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

virtual void free ()
 Free the QuadEdge quartet associated with this QuadEdge by a connect() or makeEdge() call. More...
 
const QuadEdgegetPrimary () const
 Gets the primary edge of this quadedge and its sym. More...
 
virtual void setData (void *data)
 Sets the external data value for this edge. More...
 
virtual void * getData ()
 Gets the external data value for this edge. 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...
 
QuadEdgerot () const
 Gets the dual of this edge, directed from its right to its left. More...
 
QuadEdgeinvRot () const
 Gets the dual of this edge, directed from its left to its right. More...
 
QuadEdgesym () const
 Gets the edge from the destination to the origin of this edge. More...
 
QuadEdgeoNext () const
 Gets the next CCW edge around the origin of this edge. More...
 
QuadEdgeoPrev () const
 Gets the next CW edge around (from) the origin of this edge. More...
 
QuadEdgedNext () const
 Gets the next CCW edge around (into) the destination of this edge. More...
 
QuadEdgedPrev () const
 Gets the next CW edge around (into) the destination of this edge. More...
 
QuadEdgelNext () const
 Gets the CCW edge around the left face following this edge. More...
 
QuadEdgelPrev () const
 Gets the CCW edge around the left face before this edge. More...
 
QuadEdgerNext ()
 Gets the edge around the right face ccw following this edge. More...
 
QuadEdgerPrev ()
 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 std::unique_ptr< QuadEdgemakeEdge (const Vertex &o, const Vertex &d)
 Creates a new QuadEdge quartet from Vertex o to Vertex d. More...
 
static std::unique_ptr< QuadEdgeconnect (QuadEdge &a, QuadEdge &b)
 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...
 

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 quartet of 4 edges, linked via their _rot references. Any edge in the group may be accessed using a series of rot() operations. 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 std::unique_ptr<QuadEdge> geos::triangulate::quadedge::QuadEdge::connect ( QuadEdge a,
QuadEdge b 
)
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* The caller is reponsible for freeing the returned pointer
const Vertex& geos::triangulate::quadedge::QuadEdge::dest ( ) const
inline

Gets the vertex for the edge's destination.

Returns
the destination vertex
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().

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
virtual void geos::triangulate::quadedge::QuadEdge::free ( )
virtual

Free the QuadEdge quartet associated with this QuadEdge by a connect() or makeEdge() call.

Note
DO NOT call this function on a QuadEdge that was not returned by connect() or makeEdge().
virtual void* geos::triangulate::quadedge::QuadEdge::getData ( )
virtual

Gets the external data value for this edge.

Returns
the data object
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 ( ) const

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
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.

References sym().

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.
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().

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 std::unique_ptr<QuadEdge> geos::triangulate::quadedge::QuadEdge::makeEdge ( const Vertex o,
const Vertex d 
)
static

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

Parameters
othe origin Vertex
dthe destination Vertex
Returns
the new QuadEdge* The caller is reponsible for freeing the returned pointer
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().

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
QuadEdge& geos::triangulate::quadedge::QuadEdge::rNext ( )
inline

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

Returns
the next right face edge.

References invRot(), and oNext().

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(), oPrev(), and sym().

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

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

Returns
the previous right face edge.

References oNext().

virtual void geos::triangulate::quadedge::QuadEdge::setData ( void *  data)
virtual

Sets the external data value for this edge.

Parameters
dataan object containing external data
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
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

References rot().

Referenced by dNext(), invRot(), 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: