Class NonEncroachingSplitPointFinder

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
13	package org.locationtech.jts.triangulate;
14
15
16	import org.locationtech.jts.geom.Coordinate;
17	import org.locationtech.jts.geom.LineSegment;
18
19	/**
20	* A strategy for finding constraint split points which attempts to maximise the length of the split
21	* segments while preventing further encroachment. (This is not always possible for narrow angles).
22	*
23	* @author Martin Davis
24	*/
25	public class NonEncroachingSplitPointFinder implements ConstraintSplitPointFinder {
26
27	public NonEncroachingSplitPointFinder() {}
28
29	/**
30	* A basic strategy for finding split points when nothing extra is known about the geometry of
31	* the situation.
32	*
33	* @param seg the encroached segment
34	* @param encroachPt the encroaching point
35	* @return the point at which to split the encroached segment
36	*/
37	public Coordinate findSplitPoint(Segment seg, Coordinate encroachPt) {
38	LineSegment lineSeg = seg.getLineSegment();
39	double segLen = lineSeg.getLength();
40	double midPtLen = segLen / 2;
41	SplitSegment splitSeg = new SplitSegment(lineSeg);
42
43	Coordinate projPt = projectedSplitPoint(seg, encroachPt);
44	/**
45	* Compute the largest diameter (length) that will produce a split segment which is not
46	* still encroached upon by the encroaching point (The length is reduced slightly by a
47	* safety factor)
48	*/
49	double nonEncroachDiam = projPt.distance(encroachPt) * 2 * 0.8; // .99;
50	double maxSplitLen = nonEncroachDiam;
51	if (maxSplitLen > midPtLen) {
52	maxSplitLen = midPtLen;
53	}
54	splitSeg.setMinimumLength(maxSplitLen);
55
56	splitSeg.splitAt(projPt);
57
58	return splitSeg.getSplitPoint();
59	}
60
61	/**
62	* Computes a split point which is the projection of the encroaching point on the segment
63	*
64	* @param seg
65	* @param encroachPt
66	* @return a split point on the segment
67	*/
68	public static Coordinate projectedSplitPoint(Segment seg, Coordinate encroachPt) {
69	LineSegment lineSeg = seg.getLineSegment();
70	Coordinate projPt = lineSeg.project(encroachPt);
71	return projPt;
72	}
73	}
74