Class DistanceToPoint

1	/*
2	* Copyright (c) 2016 Vivid Solutions.
3	*
4	* All rights reserved. This program and the accompanying materials
5	* are made available under the terms of the Eclipse Public License 2.0
6	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
7	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
8	* and the Eclipse Distribution License is available at
9	*
10	* http://www.eclipse.org/org/documents/edl-v10.php.
11	*/
12	package org.locationtech.jts.algorithm.distance;
13
14	import org.locationtech.jts.geom.Coordinate;
15	import org.locationtech.jts.geom.Geometry;
16	import org.locationtech.jts.geom.GeometryCollection;
17	import org.locationtech.jts.geom.LineSegment;
18	import org.locationtech.jts.geom.LineString;
19	import org.locationtech.jts.geom.Polygon;
20
21	/**
22	* Computes the Euclidean distance (L2 metric) from a {@link Coordinate} to a {@link Geometry}.
23	* Also computes two points on the geometry which are separated by the distance found.
24	*/
25	public class DistanceToPoint
26	{
27
28	public DistanceToPoint() {
29	}
30
31	public static void computeDistance(Geometry geom, Coordinate pt, PointPairDistance ptDist)
32	{
33	if (geom instanceof LineString) {
34	computeDistance((LineString) geom, pt, ptDist);
35	}
36	else if (geom instanceof Polygon) {
37	computeDistance((Polygon) geom, pt, ptDist);
38	}
39	else if (geom instanceof GeometryCollection) {
40	GeometryCollection gc = (GeometryCollection) geom;
41	for (int i = 0; i < gc.getNumGeometries(); i++) {
42	Geometry g = gc.getGeometryN(i);
43	computeDistance(g, pt, ptDist);
44	}
45	}
46	else { // assume geom is Point
47	ptDist.setMinimum(geom.getCoordinate(), pt);
48	}
49	}
50
51	public static void computeDistance(LineString line, Coordinate pt, PointPairDistance ptDist)
52	{
53	LineSegment tempSegment = new LineSegment();
54	Coordinate[] coords = line.getCoordinates();
55	for (int i = 0; i < coords.length - 1; i++) {
56	tempSegment.setCoordinates(coords[i], coords[i + 1]);
57	// this is somewhat inefficient - could do better
58	Coordinate closestPt = tempSegment.closestPoint(pt);
59	ptDist.setMinimum(closestPt, pt);
60	}
61	}
62
63	public static void computeDistance(LineSegment segment, Coordinate pt, PointPairDistance ptDist)
64	{
65	Coordinate closestPt = segment.closestPoint(pt);
66	ptDist.setMinimum(closestPt, pt);
67	}
68
69	public static void computeDistance(Polygon poly, Coordinate pt, PointPairDistance ptDist)
70	{
71	computeDistance(poly.getExteriorRing(), pt, ptDist);
72	for (int i = 0; i < poly.getNumInteriorRing(); i++) {
73	computeDistance(poly.getInteriorRingN(i), pt, ptDist);
74	}
75	}
76	}
77