//**********************************************************************
//
//<copyright>
//
//BBN Technologies, a Verizon Company
//10 Moulton Street
//Cambridge, MA 02138
//(617) 873-8000
//
//Copyright (C) BBNT Solutions LLC. All rights reserved.
//
//</copyright>
//**********************************************************************
//
//$Source:
///cvs/darwars/ambush/aar/src/com/bbn/ambush/mission/MissionHandler.java,v
//$
//$RCSfile: BoundaryCrossing.java,v $
//$Revision: 1.5 $
//$Date: 2007/02/13 20:02:13 $
//$Author: dietrick $
//
//**********************************************************************
package com.bbn.openmap.geo;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
/**
* The BoundaryCrossing class represents a location where a path
* crosses a region. Since a location can represent a region being
* left and a region being entered, you can ask it for the out
* GeoRegion and the in GeoRegion. Both won't be null at the same
* time, but either may be.
*
* @author dietrick
*/
public class BoundaryCrossing {
/**
* The Geo location of the crossing.
*/
protected Geo geo;
/**
* The GeoRegion that is being entered.
*/
protected GeoRegion in;
/**
* The GeoRegion that is being exited.
*/
protected GeoRegion out;
/**
* Creates the BoundaryCrossing. The getCrossings() factory method
* will result in BoundaryCrossings being created.
*
* @param p The Geo location
* @param r the GeoRegion being entered/exited
* @param goinin whether the path is goin' in to the region.
*/
protected BoundaryCrossing(Geo p, GeoRegion r, boolean goinin) {
geo = p;
if (goinin) {
in = r;
} else {
out = r;
}
}
public Geo getGeo() {
return geo;
}
public GeoRegion getIn() {
return in;
}
public GeoRegion getOut() {
return out;
}
/**
* The main factory method to create BoundaryCrossings. Provides a
* BoundaryCrossing.Collector so that crossing points can be
* retrieved, as well as an iterator over regions intersected.
*
* @param path GeoPath to travel over
* @param regions An ExtentIndex filled with GeoRegions.
* @return BoundaryCrossing.Collector
*/
public static Collector getCrossings(GeoPath path, Collection regions) {
Collector collector = new Collector();
CrossingIntersection crossings = new CrossingIntersection(collector);
crossings.consider(path, regions);
return collector;
}
/**
* A Collector is an object that organizes boundary crossings, as
* discovered by CrossingIntersection class.
*
* @author dietrick
*/
public static class Collector extends MatchCollector.SetMatchCollector {
List crossings = new ArrayList(10);
List lastSegmentCrossingList;
Geo lastSegmentStartingPoint;
public Collector() {}
/**
* Add a BoundaryCrossing to the collection of crossings.
*
* @param bc
*/
protected void addCrossing(BoundaryCrossing bc) {
crossings.add(bc);
}
/**
* Add a BoundaryCrossing associated with a segment and
* region. This is the main thinkin' method, called by the
* CrossingInspector with lists of crossings. This method
* organizes and orders BorderCrossings according to the
* segment order of the path that caused the crossings.
*
* @param c A list of Geos that a segement intersects with a
* region.
* @param segment GeoSegment
* @param region GeoRegion
*/
protected void addCrossing(Collection c, GeoSegment segment,
GeoRegion region) {
// We need to get all the BorderCrossings from the current
// segment all together, across regions and place them in
// order. So if the segments matches with the previous
// segment, we need to hold off add them to the crossings
// list until a segment is complete.
// Compact will probably have to look a the
// currentSegmentList to add any leftovers.
Geo start = segment.getSeg()[0];
if (lastSegmentCrossingList != null
&& lastSegmentStartingPoint.distance(start) > 0) {
// The last segment is complete, need to order the BC
// on the list and add them to the crossings.
crossings.addAll(lastSegmentCrossingList);
lastSegmentCrossingList.clear();
} else if (lastSegmentCrossingList == null) {
lastSegmentCrossingList = new ArrayList(10);
}
// The ordered list is for temporarily holding points for
// the current segment as they are placed in the right
// order.
LinkedList orderedList = new LinkedList();
// Everything in the lastSegmentCrossingList has already
// be ordered relative to what's already been searched, so
// we can just add them now to place the new points around
// them accordingly. Also, the lastSegmentCrossingList
// holds BoundaryCrossing objects, and the collection
// passed into this function doesn't have those yet.
orderedList.addAll(lastSegmentCrossingList);
// Clear out the lastSegmetnCrossingList, we'll replenish
// it with the ordered list at the end, so it will be
// ready for the next cycle.
lastSegmentCrossingList.clear();
for (Iterator it = c.iterator(); it.hasNext();) {
Geo current = (Geo) it.next();
double curDist = start.distance(current);
// We just assume that crossing point is going into
// the current region, we'll check later to make sure.
BoundaryCrossing currentBC = new BoundaryCrossing(current, region, true);
int lastCheckedIndex = 0;
BoundaryCrossing lastChecked = null;
for (Iterator it2 = orderedList.iterator(); it2.hasNext(); lastCheckedIndex++) {
lastChecked = (BoundaryCrossing) it2.next();
if (curDist < start.distance(lastChecked.geo)) {
break;
} else {
lastChecked = null;
}
}
if (lastChecked != null) {
orderedList.add(lastCheckedIndex, currentBC);
} else {
orderedList.add(currentBC);
}
}
boolean goinin = !Intersection.isPointInPolygon(start,
region.getPoints());
for (Iterator it = orderedList.iterator(); it.hasNext();) {
BoundaryCrossing bc = (BoundaryCrossing) it.next();
boolean sameRegion = (bc.in == region);
if (sameRegion) {
if (!goinin)
bc.out = bc.in;
goinin = !goinin;
}
lastSegmentCrossingList.add(bc);
}
// OK, remember at this point that the BoundaryCrossing
// Objects have be.in set to their region, and some have
// region.out set if the boundary reflects an outward
// motion. We're going to resolve this in compact();
lastSegmentStartingPoint = start;
}
/**
* An important method that cleans up the segment/region
* BoundaryCrossing order, and also resolves the
* BoundaryCrossing.in/out settings for regions. Must be
* called before the crossing iterator is retrieved, but the
* BoundaryCrossing method does that.
*/
protected void compact() {
if (lastSegmentCrossingList != null
&& !lastSegmentCrossingList.isEmpty()) {
crossings.addAll(lastSegmentCrossingList);
lastSegmentCrossingList.clear();
lastSegmentCrossingList = null;
}
Object[] bc = crossings.toArray();
crossings = new ArrayList(bc.length);
BoundaryCrossing current, previous = null;
for (int i = 0; i < bc.length; i++) {
current = (BoundaryCrossing) bc[i];
if (previous != null
&& previous.geo.distance(current.geo) == 0.0) {
// If the distances between points are zero, it's
// a border crossing and we want to merge these
// into one point, with the bc.out pointer marking
// the region being left, and the bc.in marking
// the receiving region.
if (previous.out != null)
previous.in = current.in;
if (current.out != null) {
previous.out = current.out;
}
continue;
} else {
// First point or if the distance between points
// is not zero, if the bc.out is set, then we
// should set the bc.in to null, just to indicate
// that the point reflects a crossing from outside
// any other region into that particular region.
if (current.out != null) {
current.in = null;
}
}
crossings.add(current);
previous = current;
}
}
public Iterator getCrossings() {
compact();
return crossings.iterator();
}
}
/**
* A Intersection class that knows how to call
* BoundaryCrossing.Collector to keep track of the path's
* relationship with the regions.
*/
public static class CrossingIntersection extends Intersection {
public CrossingIntersection(Collector collector) {
super(new MatchFilter.ExactMF(), collector);
}
/**
* Calls Intersection.isSegmentNearRegion() to see if segment
* is near the region. We're going to assume that this is
* going to be called with segments ordered as they appear in
* the path, in case the path is kinda crazy, and then we can
* keep track of the crossings in the right order.
*/
public boolean considerSegmentXRegion(GeoSegment segment,
GeoRegion region) {
List hits = Intersection.segmentNearPoly(segment,
region.getPoints(),
0.0);
if (hits != null) {
((Collector) collector).addCrossing(hits, segment, region);
return true;
}
return false;
}
}
}