NodingValidator.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.noding;
import java.util.Collection;
import java.util.Iterator;
import org.locationtech.jts.algorithm.LineIntersector;
import org.locationtech.jts.algorithm.RobustLineIntersector;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.GeometryFactory;
/**
* Validates that a collection of {@link SegmentString}s is correctly noded.
* Throws an appropriate exception if an noding error is found.
*
* @version 1.7
*/
public class NodingValidator {
private LineIntersector li = new RobustLineIntersector();
private Collection segStrings;
private static final GeometryFactory fact = new GeometryFactory();
public NodingValidator(Collection segStrings)
{
this.segStrings = segStrings;
}
public void checkValid()
{
// MD - is this call required? Or could it be done in the Interior Intersection code?
checkEndPtVertexIntersections();
checkInteriorIntersections();
checkCollapses();
}
/**
* Checks if a segment string contains a segment pattern a-b-a (which implies a self-intersection)
*/
private void checkCollapses()
{
for (Iterator i = segStrings.iterator(); i.hasNext(); ) {
SegmentString ss = (SegmentString) i.next();
checkCollapses(ss);
}
}
private void checkCollapses(SegmentString ss)
{
Coordinate[] pts = ss.getCoordinates();
for (int i = 0; i < pts.length - 2; i++) {
checkCollapse(pts[i], pts[i + 1], pts[i + 2]);
}
}
private void checkCollapse(Coordinate p0, Coordinate p1, Coordinate p2)
{
if (p0.equals(p2))
throw new RuntimeException("found non-noded collapse at "
+ fact.createLineString(new Coordinate[] { p0, p1, p2}));
}
/**
* Checks all pairs of segments for intersections at an interior point of a segment
*/
private void checkInteriorIntersections()
{
for (Iterator i = segStrings.iterator(); i.hasNext(); ) {
SegmentString ss0 = (SegmentString) i.next();
for (Iterator j = segStrings.iterator(); j.hasNext(); ) {
SegmentString ss1 = (SegmentString) j.next();
checkInteriorIntersections(ss0, ss1);
}
}
}
private void checkInteriorIntersections(SegmentString ss0, SegmentString ss1)
{
Coordinate[] pts0 = ss0.getCoordinates();
Coordinate[] pts1 = ss1.getCoordinates();
for (int i0 = 0; i0 < pts0.length - 1; i0++) {
for (int i1 = 0; i1 < pts1.length - 1; i1++) {
checkInteriorIntersections(ss0, i0, ss1, i1);
}
}
}
private void checkInteriorIntersections(SegmentString e0, int segIndex0, SegmentString e1, int segIndex1)
{
if (e0 == e1 && segIndex0 == segIndex1) return;
//numTests++;
Coordinate p00 = e0.getCoordinate(segIndex0);
Coordinate p01 = e0.getCoordinate(segIndex0 + 1);
Coordinate p10 = e1.getCoordinate(segIndex1);
Coordinate p11 = e1.getCoordinate(segIndex1 + 1);
li.computeIntersection(p00, p01, p10, p11);
if (li.hasIntersection()) {
if (li.isProper()
|| hasInteriorIntersection(li, p00, p01)
|| hasInteriorIntersection(li, p10, p11)) {
throw new RuntimeException("found non-noded intersection at "
+ p00 + "-" + p01
+ " and "
+ p10 + "-" + p11);
}
}
}
/**
*@return true if there is an intersection point which is not an endpoint of the segment p0-p1
*/
private boolean hasInteriorIntersection(LineIntersector li, Coordinate p0, Coordinate p1)
{
for (int i = 0; i < li.getIntersectionNum(); i++) {
Coordinate intPt = li.getIntersection(i);
if (! (intPt.equals(p0) || intPt.equals(p1)))
return true;
}
return false;
}
/**
* Checks for intersections between an endpoint of a segment string
* and an interior vertex of another segment string
*/
private void checkEndPtVertexIntersections()
{
for (Iterator i = segStrings.iterator(); i.hasNext(); ) {
SegmentString ss = (SegmentString) i.next();
Coordinate[] pts = ss.getCoordinates();
checkEndPtVertexIntersections(pts[0], segStrings);
checkEndPtVertexIntersections(pts[pts.length - 1], segStrings);
}
}
private void checkEndPtVertexIntersections(Coordinate testPt, Collection segStrings)
{
for (Iterator i = segStrings.iterator(); i.hasNext(); ) {
SegmentString ss = (SegmentString) i.next();
Coordinate[] pts = ss.getCoordinates();
for (int j = 1; j < pts.length - 1; j++) {
if (pts[j].equals(testPt))
throw new RuntimeException("found endpt/interior pt intersection at index " + j + " :pt " + testPt);
}
}
}
}