Represents a directed edge in a PlanarGraph. More...

#include <DirectedEdge.h>

Inheritance diagram for geos::planargraph::DirectedEdge:

Public Types
typedef std::list< DirectedEdge * >	NonConstList

typedef std::list< const DirectedEdge * >	ConstList

typedef std::vector< DirectedEdge * >	NonConstVect

typedef std::vector< const DirectedEdge * >	ConstVect

typedef std::vector< DirectedEdge * >	Vect

Public Member Functions
	DirectedEdge (Node newFrom, Node newTo, const geom::Coordinate &directionPt, bool newEdgeDirection)
	Constructs a DirectedEdge connecting the `from` node to the `to` node.

Edge *	getEdge () const
	Returns this DirectedEdge's parent Edge, or null if it has none.

void	setEdge (Edge *newParentEdge)
	Associates this DirectedEdge with an Edge (possibly null, indicating no associated Edge).

int	getQuadrant () const
	Returns 0, 1, 2, or 3, indicating the quadrant in which this DirectedEdge's orientation lies.

const geom::Coordinate &	getDirectionPt () const
	Returns a point to which an imaginary line is drawn from the from-node to specify this DirectedEdge's orientation.

bool	getEdgeDirection () const
	Returns whether the direction of the parent Edge (if any) is the same as that of this Directed Edge.

Node *	getFromNode () const
	Returns the node from which this DirectedEdge leaves.

Node *	getToNode () const
	Returns the node to which this DirectedEdge goes.

geom::Coordinate &	getCoordinate () const
	Returns the coordinate of the from-node.

double	getAngle () const
	Returns the angle that the start of this DirectedEdge makes with the positive x-axis, in radians.

DirectedEdge *	getSym () const
	Returns the symmetric DirectedEdge – the other DirectedEdge associated with this DirectedEdge's parent Edge.

void	setSym (DirectedEdge *newSym)
	Sets this DirectedEdge's symmetric DirectedEdge, which runs in the opposite direction.

int	compareTo (const DirectedEdge *obj) const
	Returns 1 if this DirectedEdge has a greater angle with the positive x-axis than b", 0 if the DirectedEdges are collinear, and -1 otherwise.

int	compareDirection (const DirectedEdge *e) const
	Returns 1 if this DirectedEdge has a greater angle with the positive x-axis than b", 0 if the DirectedEdges are collinear, and -1 otherwise.

std::string	print () const
	Prints a detailed string representation of this DirectedEdge to the given PrintStream.

Public Member Functions inherited from geos::planargraph::GraphComponent
virtual bool	isVisited () const
	Tests if a component has been visited during the course of a graph algorithm.

virtual void	setVisited (bool p_isVisited)
	Sets the visited flag for this component.

virtual bool	isMarked () const
	Tests if a component has been marked at some point during the processing involving this graph.

virtual void	setMarked (bool p_isMarked)
	Sets the marked flag for this component.

Static Public Member Functions
static std::vector< Edge * > *	toEdges (std::vector< DirectedEdge * > &dirEdges)
	Returns a List containing the parent Edge (possibly null) for each of the given DirectedEdges.

static void	toEdges (std::vector< DirectedEdge * > &dirEdges, std::vector< Edge * > &parentEdges)
	Add parent Edge (possibly null) of each of the given DirectedEdges to the given parentEdges vector.

Static Public Member Functions inherited from geos::planargraph::GraphComponent
template<typename T >
static void	setVisited (T start, T end, bool visited)
	Sets the Visited state for the elements of a container, from start to end iterator.

template<typename T >
static void	setVisitedMap (T start, T end, bool visited)
	Sets the Visited state for the values of each map container element, from start to end iterator.

template<typename T >
static void	setMarked (T start, T end, bool marked)
	Sets the Marked state for the elements of a container, from start to end iterator.

template<typename T >
static void	setMarkedMap (T start, T end, bool marked)
	Sets the Marked state for the values of each map container element, from start to end iterator.

Protected Attributes
Edge *	parentEdge

Node *	from

Node *	to

geom::Coordinate	p0

geom::Coordinate	p1

DirectedEdge *	sym

bool	edgeDirection

int	quadrant

double	angle

Protected Attributes inherited from geos::planargraph::GraphComponent
bool	isMarkedVar
	Variable holding ''marked'' status.

bool	isVisitedVar
	Variable holding ''visited'' status.

Friends
std::ostream &	operator<< (std::ostream &, const DirectedEdge &)
	Output operator.

Detailed Description

Represents a directed edge in a PlanarGraph.

A DirectedEdge may or may not have a reference to a parent Edge (some applications of planar graphs may not require explicit Edge objects to be created). Usually a client using a PlanarGraph will subclass DirectedEdge to add its own application-specific data and methods.

Constructor & Destructor Documentation

◆ DirectedEdge()

geos::planargraph::DirectedEdge::DirectedEdge	(	Node *	newFrom,
		Node *	newTo,
		const geom::Coordinate &	directionPt,
		bool	newEdgeDirection
	)

Constructs a DirectedEdge connecting the from node to the to node.

Parameters

newFrom	`from` node
newTo	`to` node
directionPt	specifies this DirectedEdge's direction (given by an imaginary line from the `from` node to `directionPt`)
newEdgeDirection	whether this DirectedEdge's direction is the same as or opposite to that of the parent Edge (if any)

Member Function Documentation

◆ compareDirection()

int geos::planargraph::DirectedEdge::compareDirection ( const DirectedEdge * e ) const

Returns 1 if this DirectedEdge has a greater angle with the positive x-axis than b", 0 if the DirectedEdges are collinear, and -1 otherwise.

Using the obvious algorithm of simply computing the angle is not robust, since the angle calculation is susceptible to roundoff. A robust algorithm is:

first compare the quadrants. If the quadrants are different, it it trivial to determine which std::vector is "greater".
if the vectors lie in the same quadrant, the robust Orientation::index(Coordinate, Coordinate, Coordinate) function can be used to decide the relative orientation of the vectors.

◆ compareTo()

int geos::planargraph::DirectedEdge::compareTo ( const DirectedEdge * obj ) const

Returns 1 if this DirectedEdge has a greater angle with the positive x-axis than b", 0 if the DirectedEdges are collinear, and -1 otherwise.

Using the obvious algorithm of simply computing the angle is not robust, since the angle calculation is susceptible to roundoff. A robust algorithm is:

first compare the quadrants. If the quadrants are different, it it trivial to determine which std::vector is "greater".
if the vectors lie in the same quadrant, the robust Orientation::index(Coordinate, Coordinate, Coordinate) function can be used to decide the relative orientation of the vectors.

◆ toEdges() [1/2]

static std::vector< Edge * > * geos::planargraph::DirectedEdge::toEdges ( std::vector< DirectedEdge * > & dirEdges )

static

Returns a List containing the parent Edge (possibly null) for each of the given DirectedEdges.

Note: Ownership of the returned vector is left to the caller, see the equivalent function taking a vector reference to avoid this.

◆ toEdges() [2/2]

static void geos::planargraph::DirectedEdge::toEdges	(	std::vector< DirectedEdge * > &	dirEdges,
		std::vector< Edge * > &	parentEdges
	)

static

Add parent Edge (possibly null) of each of the given DirectedEdges to the given parentEdges vector.

Note: Parents are pushed to the parentEdges vector, make sure it is empty if index-based correspondence is important.

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

planargraph/DirectedEdge.h

Public Types

Public Member Functions

Static Public Member Functions

Protected Attributes

Friends