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Fix LargestEmptyCircle to handle polygonal obstacles (#988)
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81
...s/core/src/main/java/org/locationtech/jts/algorithm/construct/IndexedDistanceToPoint.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,81 @@ | ||
| /* | ||
| * Copyright (c) 2023 Martin Davis. | ||
| * | ||
| * All rights reserved. This program and the accompanying materials | ||
| * are made available under the terms of the Eclipse Public License 2.0 | ||
| * and Eclipse Distribution License v. 1.0 which accompanies this distribution. | ||
| * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html | ||
| * and the Eclipse Distribution License is available at | ||
| * | ||
| * http://www.eclipse.org/org/documents/edl-v10.php. | ||
| */ | ||
| package org.locationtech.jts.algorithm.construct; | ||
|
|
||
| import org.locationtech.jts.geom.Coordinate; | ||
| import org.locationtech.jts.geom.Geometry; | ||
| import org.locationtech.jts.geom.Location; | ||
| import org.locationtech.jts.geom.Point; | ||
| import org.locationtech.jts.operation.distance.IndexedFacetDistance; | ||
|
|
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| /** | ||
| * Computes the distance between a point and a geometry | ||
| * (which may be a collection containing any type of geometry). | ||
| * Also computes the pair of points containing the input | ||
| * point and the nearest point on the geometry. | ||
| * | ||
| * @author mdavis | ||
| * | ||
| */ | ||
| class IndexedDistanceToPoint { | ||
|
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| private Geometry targetGeometry; | ||
| private IndexedFacetDistance facetDistance; | ||
| private IndexedPointInPolygonsLocater ptLocater; | ||
|
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| public IndexedDistanceToPoint(Geometry geom) { | ||
| this.targetGeometry = geom; | ||
| } | ||
|
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| private void init() { | ||
| if (facetDistance != null) | ||
| return; | ||
| facetDistance = new IndexedFacetDistance(targetGeometry); | ||
| ptLocater = new IndexedPointInPolygonsLocater(targetGeometry); | ||
| } | ||
|
|
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| /** | ||
| * Computes the distance from a point to the geometry. | ||
| * | ||
| * @param pt the input point | ||
| * @return the distance to the geometry | ||
| */ | ||
| public double distance(Point pt) { | ||
| init(); | ||
| //-- distance is 0 if point is inside a target polygon | ||
| if (isInArea(pt)) { | ||
| return 0; | ||
| } | ||
| return facetDistance.distance(pt); | ||
| } | ||
|
|
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| private boolean isInArea(Point pt) { | ||
| return Location.EXTERIOR != ptLocater.locate(pt.getCoordinate()); | ||
| } | ||
|
|
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| /** | ||
| * Gets the nearest locations between the geometry and a point. | ||
| * The first location lies on the geometry, | ||
| * and the second location is the provided point. | ||
| * | ||
| * @param pt the point to compute the nearest location for | ||
| * @return a pair of locations | ||
| */ | ||
| public Coordinate[] nearestPoints(Point pt) { | ||
| init(); | ||
| if (isInArea(pt)) { | ||
| Coordinate p = pt.getCoordinate(); | ||
| return new Coordinate[] { p.copy(), p.copy() }; | ||
| } | ||
| return facetDistance.nearestPoints(pt); | ||
| } | ||
| } |
67 changes: 67 additions & 0 deletions
67
...src/main/java/org/locationtech/jts/algorithm/construct/IndexedPointInPolygonsLocater.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,67 @@ | ||
| /* | ||
| * Copyright (c) 2023 Martin Davis. | ||
| * | ||
| * All rights reserved. This program and the accompanying materials | ||
| * are made available under the terms of the Eclipse Public License 2.0 | ||
| * and Eclipse Distribution License v. 1.0 which accompanies this distribution. | ||
| * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html | ||
| * and the Eclipse Distribution License is available at | ||
| * | ||
| * http://www.eclipse.org/org/documents/edl-v10.php. | ||
| */ | ||
| package org.locationtech.jts.algorithm.construct; | ||
|
|
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| import java.util.List; | ||
|
|
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| import org.locationtech.jts.algorithm.locate.IndexedPointInAreaLocator; | ||
| import org.locationtech.jts.algorithm.locate.PointOnGeometryLocator; | ||
| import org.locationtech.jts.geom.Coordinate; | ||
| import org.locationtech.jts.geom.Envelope; | ||
| import org.locationtech.jts.geom.Geometry; | ||
| import org.locationtech.jts.geom.Location; | ||
| import org.locationtech.jts.geom.util.PolygonalExtracter; | ||
| import org.locationtech.jts.index.strtree.STRtree; | ||
|
|
||
| /** | ||
| * Determines the location of a point in the polygonal elements of a geometry. | ||
| * Uses spatial indexing to provide efficient performance. | ||
| * | ||
| * @author mdavis | ||
| * | ||
| */ | ||
| class IndexedPointInPolygonsLocater implements PointOnGeometryLocator { | ||
|
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| private Geometry geom; | ||
| private List<Geometry> polys; | ||
| private STRtree index; | ||
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| public IndexedPointInPolygonsLocater(Geometry geom) { | ||
| this.geom = geom; | ||
| } | ||
|
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| private void init() { | ||
| if (polys != null) | ||
| return; | ||
| polys = PolygonalExtracter.getPolygonals(geom); | ||
| index = new STRtree(); | ||
| for (int i = 0; i < polys.size(); i++) { | ||
| Geometry poly = polys.get(i); | ||
| index.insert(poly.getEnvelopeInternal(), new IndexedPointInAreaLocator(poly)); | ||
| } | ||
| } | ||
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| @Override | ||
| public int locate(Coordinate p) { | ||
| init(); | ||
|
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| List results = index.query(new Envelope(p)); | ||
| for (int i = 0; i < results.size(); i++) { | ||
| IndexedPointInAreaLocator ptLocater = (IndexedPointInAreaLocator) results.get(i); | ||
| int loc = ptLocater.locate(p); | ||
| if (loc != Location.EXTERIOR) | ||
| return loc; | ||
| } | ||
| return Location.EXTERIOR; | ||
| } | ||
|
|
||
| } |
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59 changes: 59 additions & 0 deletions
59
modules/core/src/main/java/org/locationtech/jts/geom/util/PolygonalExtracter.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,59 @@ | ||
| /* | ||
| * Copyright (c) 2023 Martin Davis. | ||
| * | ||
| * All rights reserved. This program and the accompanying materials | ||
| * are made available under the terms of the Eclipse Public License 2.0 | ||
| * and Eclipse Distribution License v. 1.0 which accompanies this distribution. | ||
| * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html | ||
| * and the Eclipse Distribution License is available at | ||
| * | ||
| * http://www.eclipse.org/org/documents/edl-v10.php. | ||
| */ | ||
| package org.locationtech.jts.geom.util; | ||
|
|
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| import java.util.ArrayList; | ||
| import java.util.List; | ||
|
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| import org.locationtech.jts.geom.Geometry; | ||
| import org.locationtech.jts.geom.GeometryCollection; | ||
| import org.locationtech.jts.geom.MultiPolygon; | ||
| import org.locationtech.jts.geom.Polygon; | ||
|
|
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| /** | ||
| * Extracts the {@link Polygon} and {@link MultiPolygon} elements from a {@link Geometry}. | ||
| */ | ||
| public class PolygonalExtracter | ||
| { | ||
| /** | ||
| * Extracts the {@link Polygon} and {@link MultiPolygon} elements from a {@link Geometry} | ||
| * and adds them to the provided list. | ||
| * | ||
| * @param geom the geometry from which to extract | ||
| * @param list the list to add the extracted elements to | ||
| */ | ||
| public static List<Geometry> getPolygonals(Geometry geom, List<Geometry> list) | ||
| { | ||
| if (geom instanceof Polygon || geom instanceof MultiPolygon) { | ||
| list.add(geom); | ||
| } | ||
| else if (geom instanceof GeometryCollection) { | ||
| for (int i = 0; i < geom.getNumGeometries(); i++) { | ||
| getPolygonals(geom.getGeometryN(i), list); | ||
| } | ||
| } | ||
| // skip non-Polygonal elemental geometries | ||
| return list; | ||
| } | ||
|
|
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| /** | ||
| * Extracts the {@link Polygon} and {@link MultiPolygon} elements from a {@link Geometry} | ||
| * and returns them in a list. | ||
| * | ||
| * @param geom the geometry from which to extract | ||
| */ | ||
| public static List<Geometry> getPolygonals(Geometry geom) | ||
| { | ||
| return getPolygonals(geom, new ArrayList<Geometry>()); | ||
| } | ||
|
|
||
| } |
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