Package org.locationtech.jts.geomgraph.index

Class MonotoneChainEdge

java.lang.Object

org.locationtech.jts.geomgraph.index.MonotoneChainEdge

public class MonotoneChainEdge
extends java.lang.Object

MonotoneChains are a way of partitioning the segments of an edge to allow for fast searching of intersections. They have the following properties:

1. the segments within a monotone chain will never intersect each other
2. the envelope of any contiguous subset of the segments in a monotone chain is simply the envelope of the endpoints of the subset.

Property 1 means that there is no need to test pairs of segments from within the same monotone chain for intersection. Property 2 allows binary search to be used to find the intersection points of two monotone chains. For many types of real-world data, these properties eliminate a large number of segment comparisons, producing substantial speed gains.

Version:

1.7

Field Summary

Fields

Modifier and Type	Field	Description
(package private) Edge	e
(package private) Coordinate[]	pts
(package private) int[]	startIndex

Constructor Summary

Constructors

Constructor	Description
MonotoneChainEdge(Edge e)

Method Summary

Modifier and Type	Method	Description
void	computeIntersects(MonotoneChainEdge mce, SegmentIntersector si)
private void	computeIntersectsForChain(int start0, int end0, MonotoneChainEdge mce, int start1, int end1, SegmentIntersector ei)
void	computeIntersectsForChain(int chainIndex0, MonotoneChainEdge mce, int chainIndex1, SegmentIntersector si)
Coordinate[]	getCoordinates()
double	getMaxX(int chainIndex)
double	getMinX(int chainIndex)
int[]	getStartIndexes()
private boolean	overlaps(int start0, int end0, MonotoneChainEdge mce, int start1, int end1)	Tests whether the envelopes of two chain sections overlap (intersect).

Methods inherited from class java.lang.Object

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

Field Detail

e

Edge e

pts

Coordinate[] pts

startIndex

int[] startIndex

Constructor Detail

MonotoneChainEdge

public MonotoneChainEdge(Edge e)

Method Detail

getCoordinates

public Coordinate[] getCoordinates()

getStartIndexes

public int[] getStartIndexes()

getMinX

public double getMinX(int chainIndex)

getMaxX

public double getMaxX(int chainIndex)

computeIntersects

public void computeIntersects(MonotoneChainEdge mce,
                              SegmentIntersector si)

computeIntersectsForChain

public void computeIntersectsForChain(int chainIndex0,
                                      MonotoneChainEdge mce,
                                      int chainIndex1,
                                      SegmentIntersector si)

computeIntersectsForChain

private void computeIntersectsForChain(int start0,
                                       int end0,
                                       MonotoneChainEdge mce,
                                       int start1,
                                       int end1,
                                       SegmentIntersector ei)

overlaps

private boolean overlaps(int start0,
                         int end0,
                         MonotoneChainEdge mce,
                         int start1,
                         int end1)

Tests whether the envelopes of two chain sections overlap (intersect).

Parameters:

start0 -

end0 -

mce -

start1 -

end1 -

Returns:

true if the section envelopes overlap