com.vividsolutions.jts.noding.MCIndexNoder Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of JTSplus Show documentation
JTS Topology Suite 1.14 with additional functions for GeoSpark
There is a newer version: 0.1.4

/*
 * 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.index.*;
import com.vividsolutions.jts.index.chain.*;
import com.vividsolutions.jts.index.strtree.*;
import java.util.*;

/**
 * Nodes a set of {@link SegmentString}s using a index based
 * on {@link MonotoneChain}s and a {@link SpatialIndex}.
 * The {@link SpatialIndex} used should be something that supports
 * envelope (range) queries efficiently (such as a Quadtree}
 * or {@link STRtree} (which is the default index provided).
 *
 * @version 1.7
 */
public class MCIndexNoder
    extends SinglePassNoder
{
  private List monoChains = new ArrayList();
  private SpatialIndex index= new STRtree();
  private int idCounter = 0;
  private Collection nodedSegStrings;
  // statistics
  private int nOverlaps = 0;

  public MCIndexNoder()
  {
  }
  public MCIndexNoder(SegmentIntersector si)
  {
    super(si);
  }

  public List getMonotoneChains() { return monoChains; }

  public SpatialIndex getIndex() { return index; }

  public Collection getNodedSubstrings()
  {
    return  NodedSegmentString.getNodedSubstrings(nodedSegStrings);
  }

  public void computeNodes(Collection inputSegStrings)
  {
    this.nodedSegStrings = inputSegStrings;
    for (Iterator i = inputSegStrings.iterator(); i.hasNext(); ) {
      add((SegmentString) i.next());
    }
    intersectChains();
//System.out.println("MCIndexNoder: # chain overlaps = " + nOverlaps);
  }

  private void intersectChains()
  {
    MonotoneChainOverlapAction overlapAction = new SegmentOverlapAction(segInt);

    for (Iterator i = monoChains.iterator(); i.hasNext(); ) {
      MonotoneChain queryChain = (MonotoneChain) i.next();
      List overlapChains = index.query(queryChain.getEnvelope());
      for (Iterator j = overlapChains.iterator(); j.hasNext(); ) {
        MonotoneChain testChain = (MonotoneChain) j.next();
        /**
         * following test makes sure we only compare each pair of chains once
         * and that we don't compare a chain to itself
         */
        if (testChain.getId() > queryChain.getId()) {
          queryChain.computeOverlaps(testChain, overlapAction);
          nOverlaps++;
        }
        // short-circuit if possible
        if (segInt.isDone())
        	return;
      }
    }
  }

  private void add(SegmentString segStr)
  {
    List segChains = MonotoneChainBuilder.getChains(segStr.getCoordinates(), segStr);
    for (Iterator i = segChains.iterator(); i.hasNext(); ) {
      MonotoneChain mc = (MonotoneChain) i.next();
      mc.setId(idCounter++);
      index.insert(mc.getEnvelope(), mc);
      monoChains.add(mc);
    }
  }

  public class SegmentOverlapAction
      extends MonotoneChainOverlapAction
  {
    private SegmentIntersector si = null;

    public SegmentOverlapAction(SegmentIntersector si)
    {
      this.si = si;
    }

    public void overlap(MonotoneChain mc1, int start1, MonotoneChain mc2, int start2)
    {
      SegmentString ss1 = (SegmentString) mc1.getContext();
      SegmentString ss2 = (SegmentString) mc2.getContext();
      si.processIntersections(ss1, start1, ss2, start2);
    }

  }
}