/* * The JTS Topology Suite is a collection of Java classes that * implement the fundamental operations required to validate a given * geo-spatial data set to a known topological specification. * * Copyright (C) 2001 Vivid Solutions * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * For more information, contact: * * Vivid Solutions * Suite #1A * 2328 Government Street * Victoria BC V8T 5G5 * Canada * * (250)385-6040 * www.vividsolutions.com */ package com.vividsolutions.jts.noding; import com.vividsolutions.jts.algorithm.*; import com.vividsolutions.jts.geom.*; import java.util.*; /** * Nodes a set of {@link NodedSegmentString}s completely. * The set of segment strings is fully noded; * i.e. noding is repeated until no further * intersections are detected. * <p> * Iterated noding using a FLOATING precision model is not guaranteed to converge, * due to roundoff error. * This problem is detected and an exception is thrown. * Clients can choose to rerun the noding using a lower precision model. * * @version 1.7 */ public class IteratedNoder implements Noder { public static final int MAX_ITER = 5; private PrecisionModel pm; private LineIntersector li; private Collection nodedSegStrings; private int maxIter = MAX_ITER; public IteratedNoder(PrecisionModel pm) { li = new RobustLineIntersector(); this.pm = pm; li.setPrecisionModel(pm); } /** * Sets the maximum number of noding iterations performed before * the noding is aborted. * Experience suggests that this should rarely need to be changed * from the default. * The default is MAX_ITER. * * @param maxIter the maximum number of iterations to perform */ public void setMaximumIterations(int maxIter) { this.maxIter = maxIter; } public Collection getNodedSubstrings() { return nodedSegStrings; } /** * Fully nodes a list of {@link SegmentString}s, i.e. peforms noding iteratively * until no intersections are found between segments. * Maintains labelling of edges correctly through * the noding. * * @param segStrings a collection of SegmentStrings to be noded * @return a collection of the noded SegmentStrings * @throws TopologyException if the iterated noding fails to converge. */ public void computeNodes(Collection segStrings) throws TopologyException { int[] numInteriorIntersections = new int[1]; nodedSegStrings = segStrings; int nodingIterationCount = 0; int lastNodesCreated = -1; do { node(nodedSegStrings, numInteriorIntersections); nodingIterationCount++; int nodesCreated = numInteriorIntersections[0]; /** * Fail if the number of nodes created is not declining. * However, allow a few iterations at least before doing this */ //System.out.println("# nodes created: " + nodesCreated); if (lastNodesCreated > 0 && nodesCreated >= lastNodesCreated && nodingIterationCount > maxIter) { throw new TopologyException("Iterated noding failed to converge after " + nodingIterationCount + " iterations"); } lastNodesCreated = nodesCreated; } while (lastNodesCreated > 0); //System.out.println("# nodings = " + nodingIterationCount); } /** * Node the input segment strings once * and create the split edges between the nodes */ private void node(Collection segStrings, int[] numInteriorIntersections) { IntersectionAdder si = new IntersectionAdder(li); MCIndexNoder noder = new MCIndexNoder(); noder.setSegmentIntersector(si); noder.computeNodes(segStrings); nodedSegStrings = noder.getNodedSubstrings(); numInteriorIntersections[0] = si.numInteriorIntersections; //System.out.println("# intersection tests: " + si.numTests); } }