IteratedOverlayFunctions.java
/*
* Copyright (c) 2020 Martin Davis, and others.
*
* 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.jtslab;
import java.util.ArrayList;
import java.util.List;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.MultiPolygon;
import org.locationtech.jts.geom.Polygon;
import org.locationtech.jts.geom.PrecisionModel;
import org.locationtech.jts.geom.util.PolygonExtracter;
import org.locationtech.jts.index.quadtree.Quadtree;
import org.locationtech.jts.operation.overlayng.OverlayNG;
import org.locationtech.jts.operation.overlayng.OverlayNGRobust;
public class IteratedOverlayFunctions {
public static Geometry overlayOld(Geometry coll) {
return overlay(coll, false, null);
}
public static Geometry overlayNG(Geometry coll) {
return overlay(coll, true, null);
}
public static Geometry overlaySR(Geometry coll, double scale) {
PrecisionModel pm = new PrecisionModel(scale);
return overlay(coll, true, pm);
}
private static Geometry overlay(Geometry coll, boolean useNG, PrecisionModel pm) {
List<Geometry> result = new ArrayList<Geometry>();
for (int i = 0; i < coll.getNumGeometries(); i++) {
Geometry inGeom = coll.getGeometryN(i);
int size = result.size();
for (int j = 0; j < size; j++) {
Geometry resGeom = result.get(j);
if (resGeom.isEmpty()) continue;
Geometry intGeom = extractPolygons(overlayIntersection(resGeom, inGeom, useNG, pm));
if (! intGeom.isEmpty()) {
result.add(intGeom);
Geometry resDiff = extractPolygons(overlayDifference(resGeom, intGeom, useNG, pm));
result.set( j, resDiff );
inGeom = extractPolygons(overlayDifference(inGeom, intGeom, useNG, pm));
}
}
// keep remainder of input (non-overlapped part)
if (! inGeom.isEmpty()) {
result.addAll( PolygonExtracter.getPolygons( inGeom ) );
//result.add( inGeom );
}
}
// TODO: return only non-empty polygons
List<Polygon> resultPolys = extractPolygonsNonEmpty(result);
return coll.getFactory().buildGeometry(resultPolys);
}
public static Geometry overlayIndexedNG(Geometry coll) {
return overlayIndexed(coll, true, null);
}
private static Geometry overlayIndexed(Geometry coll, boolean useNG, PrecisionModel pm) {
Quadtree tree = new Quadtree();
for (int i = 0; i < coll.getNumGeometries(); i++) {
Geometry inGeom = coll.getGeometryN(i);
List<Polygon> results = tree.query( inGeom.getEnvelopeInternal() );
for (Polygon resPoly : results) {
Geometry intGeom = extractPolygons(overlayIntersection(resPoly, inGeom, useNG, pm));
List<Polygon> intList = PolygonExtracter.getPolygons( intGeom );
// resultant is overlapped by next input
if (! intGeom.isEmpty() && intList.size() > 0) {
tree.remove(resPoly.getEnvelopeInternal(), resPoly);
for (Polygon intPoly : intList) {
tree.insert( intPoly.getEnvelopeInternal(), intPoly );
Geometry resDiff = overlayDifference(resPoly, intGeom, useNG, pm);
insertPolys(resDiff, tree);
inGeom = extractPolygons(overlayDifference(inGeom, intPoly, useNG, pm));
}
}
}
// keep remainder of input
insertPolys(inGeom, tree);
}
List result = tree.queryAll();
return coll.getFactory().buildGeometry(result);
}
private static void insertPolys(Geometry geom, Quadtree tree) {
if (geom.isEmpty()) return;
List<Polygon> polyList = PolygonExtracter.getPolygons( geom );
for (Polygon poly : polyList) {
tree.insert(poly.getEnvelopeInternal(), poly);
}
}
private static Geometry overlayIntersection(Geometry a, Geometry b, boolean useNG, PrecisionModel pm) {
if (useNG) {
if (pm == null)
return OverlayNGRobust.overlay(a, b, OverlayNG.INTERSECTION);
return OverlayNG.overlay(a, b, OverlayNG.INTERSECTION, pm);
}
return a.intersection(b);
}
private static Geometry overlayDifference(Geometry a, Geometry b, boolean useNG, PrecisionModel pm) {
if (useNG) {
if (pm == null)
return OverlayNGRobust.overlay(a, b, OverlayNG.DIFFERENCE);
return OverlayNG.overlay(a, b, OverlayNG.DIFFERENCE, pm);
}
return a.difference(b);
}
private static Geometry extractPolygons(Geometry geom) {
List polys = PolygonExtracter.getPolygons(geom);
return geom.getFactory().buildGeometry(polys);
}
private static List<Polygon> extractPolygonsNonEmpty(List<Geometry> geoms) {
List<Polygon> exPolys = new ArrayList<Polygon>();
for (Geometry geom : geoms) {
if (! geom.isEmpty()) {
if (geom instanceof Polygon) {
exPolys.add((Polygon) geom);
}
else if (geom instanceof MultiPolygon) {
exPolys.addAll(PolygonExtracter.getPolygons(geom));
}
}
}
return exPolys;
}
}