/* * 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.geom.*; import com.vividsolutions.jts.algorithm.LineIntersector; import com.vividsolutions.jts.noding.*;; //import com.vividsolutions.jts.util.Debug; /** * Detects and records an intersection between two {@link SegmentString}s, * if one exists. Only a single intersection is recorded. * This strategy can be configured to search for proper intersections. * In this case, the presence of <i>any</i> kind of intersection will still be recorded, * but searching will continue until either a proper intersection has been found * or no intersections are detected. * * @version 1.7 */ public class SegmentIntersectionDetector implements SegmentIntersector { private LineIntersector li; private boolean findProper = false; private boolean findAllTypes = false; private boolean hasIntersection = false; private boolean hasProperIntersection = false; private boolean hasNonProperIntersection = false; private Coordinate intPt = null; private Coordinate[] intSegments = null; /** * Creates an intersection finder * * @param li the LineIntersector to use */ public SegmentIntersectionDetector(LineIntersector li) { this.li = li; } public void setFindProper(boolean findProper) { this.findProper = findProper; } public void setFindAllIntersectionTypes(boolean findAllTypes) { this.findAllTypes = findAllTypes; } /** * Tests whether an intersection was found. * * @return true if an intersection was found */ public boolean hasIntersection() { return hasIntersection; } /** * Tests whether a proper intersection was found. * * @return true if a proper intersection was found */ public boolean hasProperIntersection() { return hasProperIntersection; } /** * Tests whether a non-proper intersection was found. * * @return true if a non-proper intersection was found */ public boolean hasNonProperIntersection() { return hasNonProperIntersection; } /** * Gets the computed location of the intersection. * Due to round-off, the location may not be exact. * * @return the coordinate for the intersection location */ public Coordinate getIntersection() { return intPt; } /** * Gets the endpoints of the intersecting segments. * * @return an array of the segment endpoints (p00, p01, p10, p11) */ public Coordinate[] getIntersectionSegments() { return intSegments; } /** * This method is called by clients * of the {@link SegmentIntersector} class to process * intersections for two segments of the {@link SegmentString}s being intersected. * Note that some clients (such as {@link MonotoneChain}s) may optimize away * this call for segment pairs which they have determined do not intersect * (e.g. by an disjoint envelope test). */ public void processIntersections( SegmentString e0, int segIndex0, SegmentString e1, int segIndex1 ) { // don't bother intersecting a segment with itself if (e0 == e1 && segIndex0 == segIndex1) return; Coordinate p00 = e0.getCoordinates()[segIndex0]; Coordinate p01 = e0.getCoordinates()[segIndex0 + 1]; Coordinate p10 = e1.getCoordinates()[segIndex1]; Coordinate p11 = e1.getCoordinates()[segIndex1 + 1]; li.computeIntersection(p00, p01, p10, p11); // if (li.hasIntersection() && li.isProper()) Debug.println(li); if (li.hasIntersection()) { // System.out.println(li); // record intersection info hasIntersection = true; boolean isProper = li.isProper(); if (isProper) hasProperIntersection = true; if (! isProper) hasNonProperIntersection = true; /** * If this is the kind of intersection we are searching for * OR no location has yet been recorded * save the location data */ boolean saveLocation = true; if (findProper && ! isProper) saveLocation = false; if (intPt == null || saveLocation) { // record intersection location (approximate) intPt = li.getIntersection(0); // record intersecting segments intSegments = new Coordinate[4]; intSegments[0] = p00; intSegments[1] = p01; intSegments[2] = p10; intSegments[3] = p11; } } } public boolean isDone() { /** * If finding all types, we can stop * when both possible types have been found. */ if (findAllTypes) { return hasProperIntersection && hasNonProperIntersection; } /** * If searching for a proper intersection, only stop if one is found */ if (findProper) { return hasProperIntersection; } return hasIntersection; } }