OverlayOptFunctions.java
/*
* Copyright (c) 2019 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 org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.prep.PreparedGeometry;
import org.locationtech.jts.geom.prep.PreparedGeometryFactory;
/**
* Functions to test using spatial predicates
* as a filter in front of overlay operations
* to optimize performance.
*
* @author Martin Davis
*
*/
public class OverlayOptFunctions {
/**
* Use spatial predicates as a filter
* in front of intersection.
*
* @param a a geometry
* @param b a geometry
* @return the intersection of the geometries
*/
public static Geometry intersectionOpt(Geometry a, Geometry b) {
if (! a.intersects(b)) return null;
if (a.covers(b)) return b.copy();
if (b.covers(a)) return a.copy();
return a.intersection(b);
}
/**
* Use prepared geometry spatial predicates as a filter
* in front of intersection,
* with the first operand prepared.
*
* @param a a geometry to prepare
* @param b a geometry
* @return the intersection of the geometries
*/
public static Geometry intersectionOptPrep(Geometry a, Geometry b) {
PreparedGeometry pg = cacheFetch(a);
if (! pg.intersects(b)) return null;
if (pg.covers(b)) return b.copy();
return a.intersection(b);
}
private static Geometry cacheKey = null;
private static PreparedGeometry cache = null;
private static PreparedGeometry cacheFetch(Geometry g) {
if (g != cacheKey) {
cacheKey = g;
cache = (new PreparedGeometryFactory()).create(g);
}
return cache;
}
}