Package com.google.common.geometry

Class S2EdgeUtil.EdgeCrosser

java.lang.Object

com.google.common.geometry.S2EdgeUtil.EdgeCrosser

Enclosing class:

S2EdgeUtil

public static final class S2EdgeUtil.EdgeCrosser
extends Object

Used to efficiently test a fixed edge AB against an edge chain. To use it, initialize with the edge AB, and call robustCrossing(S2Point, S2Point) or edgeOrVertexCrossing(S2Point, S2Point) with each edge of the chain.

This class is not thread-safe.

Constructor Summary

Constructors

Constructor	Description
EdgeCrosser()	Constructs an uninitialized edge crosser.
EdgeCrosser(S2Point a, S2Point b)	Convenience constructor that calls init() with the given fixed edge AB.
EdgeCrosser(S2Point a, S2Point b, S2Point c)	AB is the given fixed edge, and C is the first vertex of the vertex chain.

Method Summary

Modifier and Type	Method	Description
boolean	edgeOrVertexCrossing(S2Point d)	This method is equivalent to the edgeOrVertexCrossing(com.google.common.geometry.S2Point) method defined below.
boolean	edgeOrVertexCrossing(S2Point c, S2Point d)	As edgeOrVertexCrossing(S2Point), but restarts at c if that is not the previous endpoint.
void	init(S2Point a, S2Point b)
void	restartAt(S2Point c)	Call this method when your chain 'jumps' to a new place.
int	robustCrossing(S2Point d)	This method is equivalent to calling the robustCrossing(com.google.common.geometry.S2Point) function (defined below) on the edges AB and CD.
int	robustCrossing(S2Point c, S2Point d)	As robustCrossing(S2Point), but restarts at c if that is not the previous endpoint.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

EdgeCrosser

public EdgeCrosser()

Constructs an uninitialized edge crosser. Invoke init(S2Point, S2Point) before calling the other methods.

EdgeCrosser

public EdgeCrosser(S2Point a,
 S2Point b)

Convenience constructor that calls init() with the given fixed edge AB.

EdgeCrosser

public EdgeCrosser(S2Point a,
 S2Point b,
 S2Point c)

AB is the given fixed edge, and C is the first vertex of the vertex chain. Equivalent to using the two-arg constructor and calling restartAt(c).

Method Details

init

public void init(S2Point a,
 S2Point b)

restartAt

public void restartAt(S2Point c)

Call this method when your chain 'jumps' to a new place.

robustCrossing

public int robustCrossing(S2Point d)

This method is equivalent to calling the robustCrossing(com.google.common.geometry.S2Point) function (defined below) on the edges AB and CD. It returns +1 if there is a crossing, -1 if there is no crossing, and 0 if two points from different edges are the same. Returns 0 or -1 if either edge is degenerate. As a side effect, it saves vertex D to be used as the next vertex C.

robustCrossing

public int robustCrossing(S2Point c,
 S2Point d)

As robustCrossing(S2Point), but restarts at c if that is not the previous endpoint.

edgeOrVertexCrossing

public boolean edgeOrVertexCrossing(S2Point d)

This method is equivalent to the edgeOrVertexCrossing(com.google.common.geometry.S2Point) method defined below. It is similar to robustCrossing(com.google.common.geometry.S2Point), but handles cases where two vertices are identical in a way that makes it easy to implement point-in-polygon containment tests.

edgeOrVertexCrossing

public boolean edgeOrVertexCrossing(S2Point c,
 S2Point d)

As edgeOrVertexCrossing(S2Point), but restarts at c if that is not the previous endpoint.