edu.uci.ics.dillenco.simplegraph01
Class QEdge

java.lang.Object
  edu.uci.ics.dillenco.simplegraph01.QEdge

public class QEdge
extends Object

A QEdge represents a QuadEdge, in the sense of the Guibas-Stolfi quadedge structure.

Essentially a QEdge represent four half-edges, which may be thought of as rotations of one another. One of the half-edges is the canonical representative, e₀ The remaining three half-edges are e₀Rot¹, e₀Rot², and e₀Rot³.

Field Summary

int

permID

Method Summary

String	charName(Graph g)
HalfEdge	getHalfEdge(int r) Return a HalfEdge representing the the half-edge e0Rotr.
Node	getHead(int r) Return the the head of the half-edge e0Rotr, which must be part of a directed edge.
HalfEdge	getNext(int r) Return a HalfEdge representing the next half edge having the same origin node as the HalfEdge e0Rotr.
Node	getOppNode(Node v) Returns the node opposite v along this QEdge.
Node	getOrigin(int r) Return the origin node of the HalfEdge e0Rotr.
Node	getTail(int r) Return the the tail of the half-edge e0Rotr, which must be part of a directed edge.
boolean	isDirected(int r) Return whether the half-edge e0Rotr.
boolean	isHead(int r) Return whether the origin of the half-edge e0Rotr is the head of the edge containing this half-edge (i.e., whether this edge is directed toward the origin of the half-edge).
boolean	isTail(int r) Return whether the origin of the half-edge e0Rotr is the tail of the edge containing this half-edge (i.e., whether this edge is directed away from the origin of the half-edge).
String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

permID

public final int permID

Method Detail

toString

public String toString()

Overrides:

toString in class Object

charName

public String charName(Graph g)

getOppNode

public Node getOppNode(Node v)

Returns the node opposite v along this QEdge. In the GS formulation, if v is e₀Rot^r.Origin, the vertex returned is e₀Rot^(r+2)%4.Origin. If no such r exists, a GraphCheckException is thrown.

Parameters:

v - the Node whose opposite end is to be returned.

Returns:

the Node opposite v on this QEdge.

getNext

public HalfEdge getNext(int r)

Return a HalfEdge representing the next half edge having the same origin node as the HalfEdge e₀Rot^r. The value returned by this method is the value of the Next field in the GS formulation, which is the half edge e₀Rot^rOnext.

Parameters:

r - the rotation index, in the range 0..3.

getOrigin

public Node getOrigin(int r)

Return the origin node of the HalfEdge e₀Rot^r.

Parameters:

r - the rotation index, in the range 0..3.

getHalfEdge

public HalfEdge getHalfEdge(int r)

Return a HalfEdge representing the the half-edge e₀Rot^r.

Parameters:

r - the rotation index, in the range 0..3.

isDirected

public boolean isDirected(int r)

Return whether the half-edge e₀Rot^r. is part of a directed edge.

Parameters:

r - the rotation index, in the range 0..3.

Returns:

true if the indicated half-edge is part of a directed edge

isHead

public boolean isHead(int r)

Return whether the origin of the half-edge e₀Rot^r is the head of the edge containing this half-edge (i.e., whether this edge is directed toward the origin of the half-edge). If the edge is either undirected or directed away from the origin of the half-edge, false is returned.

Parameters:

r - the rotation index, in the range 0..3.

Returns:

true if the origin is the head of the edge.

isTail

public boolean isTail(int r)

Return whether the origin of the half-edge e₀Rot^r is the tail of the edge containing this half-edge (i.e., whether this edge is directed away from the origin of the half-edge). If the edge is either undirected or directed toward the origin of the half-edge, false is returned.

Parameters:

r - the rotation index, in the range 0..3.

Returns:

true if the origin is the tail of the edge.

getHead

public Node getHead(int r)

Return the the head of the half-edge e₀Rot^r, which must be part of a directed edge. If the edge is directed, the return value will either be the origin of this half-edge or the origin of the symmetric half-edge e₀Rot^rSym. If the edge is not directed, a GraphCheckException will be thrown.

Parameters:

r - the rotation index, in the range 0..3.

Returns:

the head of the edge to which this half-edge belongs.

getTail

public Node getTail(int r)

Return the the tail of the half-edge e₀Rot^r, which must be part of a directed edge. If the edge is directed, the return value will either be the origin of this half-edge or the origin of the symmetric half-edge e₀Rot^rSym. If the edge is not directed, a GraphCheckException will be thrown.

Parameters:

r - the rotation index, in the range 0..3.

Returns:

the tail of the edge to which this half-edge belongs.