SimpleEdgeSetIntersector.java
/*
* Copyright (c) 2016 Vivid Solutions.
*
* 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.jts.geomgraph.index;
import java.util.Iterator;
import java.util.List;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geomgraph.Edge;
/**
* 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);
}
}
}
}