Package org.locationtech.jts.algorithm
Class RayCrossingCounter
java.lang.Object
org.locationtech.jts.algorithm.RayCrossingCounter
Counts the number of segments crossed by a horizontal ray extending to the right
from a given point, in an incremental fashion.
This can be used to determine whether a point lies in a
Polygonal
geometry.
The class determines the situation where the point lies exactly on a segment.
When being used for Point-In-Polygon determination, this case allows short-circuiting
the evaluation.
This class handles polygonal geometries with any number of shells and holes. The orientation of the shell and hole rings is unimportant. In order to compute a correct location for a given polygonal geometry, it is essential that all segments are counted which
- touch the ray
- lie in in any ring which may contain the point
This implementation uses the extended-precision orientation test, to provide maximum robustness and consistency within other algorithms.
- Author:
- Martin Davis
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
countSegment
(Coordinate p1, Coordinate p2) Counts a segmentint
Gets theLocation
of the point relative to the ring, polygon or multipolygon from which the processed segments were provided.boolean
Reports whether the point lies exactly on one of the supplied segments.boolean
Tests whether the point lies in or on the ring, polygon or multipolygon from which the processed segments were provided.static int
locatePointInRing
(Coordinate p, Coordinate[] ring) Determines theLocation
of a point in a ring.static int
Determines theLocation
of a point in a ring.
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Constructor Details
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RayCrossingCounter
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Method Details
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locatePointInRing
Determines theLocation
of a point in a ring. This method is an exemplar of how to use this class.- Parameters:
p
- the point to testring
- an array of Coordinates forming a ring- Returns:
- the location of the point in the ring
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locatePointInRing
Determines theLocation
of a point in a ring.- Parameters:
p
- the point to testring
- a coordinate sequence forming a ring- Returns:
- the location of the point in the ring
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countSegment
Counts a segment- Parameters:
p1
- an endpoint of the segmentp2
- another endpoint of the segment
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isOnSegment
public boolean isOnSegment()Reports whether the point lies exactly on one of the supplied segments. This method may be called at any time as segments are processed. If the result of this method is true, no further segments need be supplied, since the result will never change again.- Returns:
- true if the point lies exactly on a segment
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getLocation
public int getLocation()Gets theLocation
of the point relative to the ring, polygon or multipolygon from which the processed segments were provided.This method only determines the correct location if all relevant segments must have been processed.
- Returns:
- the Location of the point
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isPointInPolygon
public boolean isPointInPolygon()Tests whether the point lies in or on the ring, polygon or multipolygon from which the processed segments were provided.This method only determines the correct location if all relevant segments must have been processed.
- Returns:
- true if the point lies in or on the supplied polygon
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