/*
* 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; }
}