/* * 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; /** * Computes the intersections between two line segments in {@link SegmentString}s * and adds them to each string. * The {@link SegmentIntersector} is passed to a {@link Noder}. * The {@link addIntersections} method is called whenever the {@link Noder} * detects that two SegmentStrings <i>might</i> intersect. * This class is an example of the <i>Strategy</i> pattern. * * @version 1.7 */ public class IntersectionAdder implements SegmentIntersector { public static boolean isAdjacentSegments(int i1, int i2) { return Math.abs(i1 - i2) == 1; } /** * These variables keep track of what types of intersections were * found during ALL edges that have been intersected. */ private boolean hasIntersection = false; private boolean hasProper = false; private boolean hasProperInterior = false; private boolean hasInterior = false; // the proper intersection point found private Coordinate properIntersectionPoint = null; private LineIntersector li; private boolean isSelfIntersection; //private boolean intersectionFound; public int numIntersections = 0; public int numInteriorIntersections = 0; public int numProperIntersections = 0; // testing only public int numTests = 0; public IntersectionAdder(LineIntersector li) { this.li = li; } public LineIntersector getLineIntersector() { return li; } /** * @return the proper intersection point, or <code>null</code> if none was found */ public Coordinate getProperIntersectionPoint() { return properIntersectionPoint; } public boolean hasIntersection() { return hasIntersection; } /** * A proper intersection is an intersection which is interior to at least two * line segments. Note that a proper intersection is not necessarily * in the interior of the entire Geometry, since another edge may have * an endpoint equal to the intersection, which according to SFS semantics * can result in the point being on the Boundary of the Geometry. */ public boolean hasProperIntersection() { return hasProper; } /** * A proper interior intersection is a proper intersection which is <b>not</b> * contained in the set of boundary nodes set for this SegmentIntersector. */ public boolean hasProperInteriorIntersection() { return hasProperInterior; } /** * An interior intersection is an intersection which is * in the interior of some segment. */ public boolean hasInteriorIntersection() { return hasInterior; } /** * A trivial intersection is an apparent self-intersection which in fact * is simply the point shared by adjacent line segments. * Note that closed edges require a special check for the point shared by the beginning * and end segments. */ private boolean isTrivialIntersection(SegmentString e0, int segIndex0, SegmentString e1, int segIndex1) { if (e0 == e1) { if (li.getIntersectionNum() == 1) { if (isAdjacentSegments(segIndex0, segIndex1)) return true; if (e0.isClosed()) { int maxSegIndex = e0.size() - 1; if ( (segIndex0 == 0 && segIndex1 == maxSegIndex) || (segIndex1 == 0 && segIndex0 == maxSegIndex) ) { return true; } } } } return false; } /** * 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 ) { if (e0 == e1 && segIndex0 == segIndex1) return; numTests++; 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()) { //intersectionFound = true; numIntersections++; if (li.isInteriorIntersection()) { numInteriorIntersections++; hasInterior = true; //System.out.println(li); } // if the segments are adjacent they have at least one trivial intersection, // the shared endpoint. Don't bother adding it if it is the // only intersection. if (! isTrivialIntersection(e0, segIndex0, e1, segIndex1)) { hasIntersection = true; ((NodedSegmentString) e0).addIntersections(li, segIndex0, 0); ((NodedSegmentString) e1).addIntersections(li, segIndex1, 1); if (li.isProper()) { numProperIntersections++; //Debug.println(li.toString()); Debug.println(li.getIntersection(0)); //properIntersectionPoint = (Coordinate) li.getIntersection(0).clone(); hasProper = true; hasProperInterior = true; } } } } /** * Always process all intersections * * @return false always */ public boolean isDone() { return false; } }