com.vividsolutions.jts.geomgraph.index.SimpleEdgeSetIntersector 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.geomgraph.index;

import java.util.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.geomgraph.*;

/**
 * Finds all intersections in one or two sets of edges,
 * using the straightforward method of
 * comparing all segments.
 * This algorithm is too slow for production use, but is useful for testing purposes.
 * @version 1.7
 */
public class SimpleEdgeSetIntersector
  extends EdgeSetIntersector
{
  // statistics information
  int nOverlaps;

  public SimpleEdgeSetIntersector() {
  }

  public void computeIntersections(List edges, SegmentIntersector si, boolean testAllSegments)
  {
    nOverlaps = 0;

    for (Iterator i0 = edges.iterator(); i0.hasNext(); ) {
      Edge edge0 = (Edge) i0.next();
      for (Iterator i1 = edges.iterator(); i1.hasNext(); ) {
        Edge edge1 = (Edge) i1.next();
        if (testAllSegments || edge0 != edge1)
          computeIntersects(edge0, edge1, si);
      }
    }
  }


  public void computeIntersections(List edges0, List edges1, SegmentIntersector si)
  {
    nOverlaps = 0;

    for (Iterator i0 = edges0.iterator(); i0.hasNext(); ) {
      Edge edge0 = (Edge) i0.next();
      for (Iterator i1 = edges1.iterator(); i1.hasNext(); ) {
        Edge edge1 = (Edge) i1.next();
        computeIntersects(edge0, edge1, si);
      }
    }
  }

  /**
   * Performs a brute-force comparison of every segment in each Edge.
   * This has n^2 performance, and is about 100 times slower than using
   * monotone chains.
   */
  private void computeIntersects(Edge e0, Edge e1, SegmentIntersector si)
  {
   Coordinate[] pts0 = e0.getCoordinates();
    Coordinate[] pts1 = e1.getCoordinates();
    for (int i0 = 0; i0 < pts0.length - 1; i0++) {
      for (int i1 = 0; i1 < pts1.length - 1; i1++) {
        si.addIntersections(e0, i0, e1, i1);
      }
    }
  }
}