/**
* RESTRICTED RIGHTS LEGEND
*
* BBNT Solutions LLC
* A Verizon Company
* 10 Moulton Street
* Cambridge, MA 02138
* (617) 873-3000
*
* Copyright BBNT Solutions LLC 2001, 2002 All Rights Reserved
*
*/
package com.bbn.openmap.geo;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
/**
* Contains great circle intersection algorithms and helper methods. Sources:
* http://williams.best.vwh.net/intersect.htm
* http://mathforum.org/library/drmath/view/60711.html
* <P>
* The Intersection class has been updated to manage query intersections of
* GeoExtents over other GeoExtents. MatchCollectors and MatchFilters can be
* used to help optimize the search and manage the results.
*
* @author Sachin Date
* @author Ken Anderson
* @version $Revision: 1.20 $ on $Date: 2009/01/21 01:24:42 $
*/
public class Intersection {
protected final MatchFilter filter;
protected final MatchCollector collector;
/**
* Create an Intersection class that will use the provided MatchFilter and
* MatchCollector.
*
* @param filter
* @param collector
*/
public Intersection(MatchFilter filter, MatchCollector collector) {
this.filter = filter;
this.collector = collector;
}
/**
* Create an Intersection class that will use the
* MatchFilter.MatchParameters class with STRICT settings, and a
* MatchCollector.SetMatchCollector.
*/
public static Intersection intersector() {
return new Intersection(new MatchFilter.MatchParametersMF(MatchParameters.STRICT), new MatchCollector.SetMatchCollector());
}
/**
* Create an Intersection class that will use the
* MatchFilter.MatchParameters class with provided settings, and a
* MatchCollector.SetMatchCollector.
*/
public static Intersection intersector(MatchParameters params) {
return new Intersection(new MatchFilter.MatchParametersMF(params), new MatchCollector.SetMatchCollector());
}
/**
* Create an Intersection class that will use the
* MatchFilter.MatchParameters class with provided settings, and a
* MatchCollector.CollectionMatchCollector with the provided collector.
*/
public static Intersection intersector(MatchParameters params, final Collection c) {
return new Intersection(new MatchFilter.MatchParametersMF(params), new MatchCollector.CollectionMatchCollector(c));
}
/**
* Create an Intersection class that will use the provided MatchFilter class
* and the provided MatchCollector.
*/
public static Intersection intersector(MatchFilter filter, MatchCollector collector) {
return new Intersection(filter, collector);
}
/**
* Retrieve the MatchCollector that contains the results from the
* Intersection query.
*
* @return MatchCollector that can be used to retrieve intersection results.
*/
public MatchCollector getCollector() {
return collector;
}
/**
* Retrieve the MatchFilter that can be used to control which GeoExtents are
* considered for Intersection queries.
*
* @return The MatchFilter used to process intersection results.
*/
public MatchFilter getFilter() {
return filter;
}
/**
* Asks the Intersection class to calculate the relationships between object
* a and b. Calls the other consider methods, depending on what a and b are.
* Consult the MatchCollector for the results.
*
* @param a A GeoExtent object, generally.
* @param b A ExtentImpl object or GeoExtent object, generally.
*/
public void consider(Object a, Object b) {
if (b instanceof Collection) {
if (a instanceof GeoRegion) {
considerRegionXRegions((GeoRegion) a, (Collection) b);
} else if (a instanceof GeoPath) {
considerPathXRegions((GeoPath) a, (Collection) b);
} else if (a instanceof GeoPoint) {
considerPointXRegions((GeoPoint) a, (Collection) b);
}
} else if (b instanceof GeoRegion) {
if (a instanceof GeoRegion) {
considerRegionXRegion((GeoRegion) a, (GeoRegion) b);
} else if (a instanceof GeoPath) {
considerPathXRegion((GeoPath) a, (GeoRegion) b);
} else if (a instanceof GeoPoint) {
considerPointXRegion((GeoPoint) a, (GeoRegion) b);
}
}
}
/**
* Loads the collector with regions from the Collection that intersect with
* r.
*
* @param r the region in question
* @param regions a Collection of GeoRegions.
*/
public void considerRegionXRegions(GeoRegion r, Collection regions) {
/*
* since the path is closed we'll check the region index for the whole
* thing instead of segment-by-segment
*/
Iterator possibles;
if (regions instanceof ExtentIndex) {
// if we've got an index, narrow the set down
possibles = ((ExtentIndex) regions).iterator(r);
} else {
possibles = regions.iterator();
}
while (possibles.hasNext()) {
GeoExtent extent = (GeoExtent) possibles.next();
if (extent instanceof GeoRegion) {
considerRegionXRegion(r, (GeoRegion) extent);
} else if (extent instanceof GeoPath) {
// This body used to be the following:
// considerPathXRegion((GeoPath) extent, r);
// but this reverses the match order and leads to "r" getting
// collected
// instead of extent. I've inlined the essential body and left
// it here
for (GeoPath.SegmentIterator pit = ((GeoPath) extent).segmentIterator(); pit.hasNext();) {
GeoSegment seg = pit.nextSegment();
if (filter.preConsider(seg, r) && considerSegmentXRegion(seg, r)) {
collector.collect(seg, extent);
}
}
} else {
// usually, getting here means poly region vs radial region
BoundingCircle bc = extent.getBoundingCircle();
BoundingCircle rbc = r.getBoundingCircle();
// first pass check - the bounding circles intersect
if (rbc.intersects(bc.getCenter(), bc.getRadius() + filter.getHRange())) {
GeoArray pts = r.getPoints();
if (isPointInPolygon(bc.getCenter(), pts)) {
// the center of extent is inside r
collector.collect(r, extent);
} else if (isPointNearPoly(bc.getCenter(), pts, bc.getRadius() + filter.getHRange())) {
// Center+radius of extent is within range an edge of
// the r
collector.collect(r, extent);
} // else no intersection
}
}
}
}
/**
* Puts the region in the Collector if r intersects with it.
*
* @param r
* @param region
*/
public void considerRegionXRegion(GeoRegion r, GeoRegion region) {
/* these must be cheap! */
GeoArray rBoundary = r.getPoints();
/* get the first path point */
Geo rPoint = rBoundary.get(0, new Geo());
GeoArray regionBoundary = region.getPoints();
Geo regionPoint = regionBoundary.get(0, new Geo());
// check for total containment
if (Intersection.isPointInPolygon(rPoint, regionBoundary) || Intersection.isPointInPolygon(regionPoint, rBoundary)
// || Intersection.isPointInPolygon(region.getBoundingCircle()
// .getCenter(), rBoundary)
// || Intersection.isPointInPolygon(r.getBoundingCircle()
// .getCenter(), regionBoundary)
) {
collector.collect(r, region);
} else {
// gotta try harder, so we fall back to segment-by-segment
// intersections
for (GeoPath.SegmentIterator pit = r.segmentIterator(); pit.hasNext();) {
GeoSegment seg = pit.nextSegment();
if (filter.preConsider(seg, region) && considerSegmentXRegion(seg, region)) {
collector.collect(seg, region);
// For the default implementation, we just care
// about first hit.
return;
}
}
}
}
/**
* Puts regions in the Collector if they intersect the path.
*
* @param path
* @param regions
*/
public void considerPathXRegions(GeoPath path, Collection regions) {
/*
* Since the path is open, then our best bet is to check each segment
* separately
*/
for (GeoPath.SegmentIterator pit = path.segmentIterator(); pit.hasNext();) {
GeoSegment seg = pit.nextSegment();
Iterator rit;
if (regions instanceof ExtentIndex) {
rit = ((ExtentIndex) regions).iterator(seg);
} else {
rit = regions.iterator();
}
while (rit.hasNext()) {
GeoExtent extent = (GeoExtent) rit.next();
if (filter.preConsider(path, extent)) {
if (extent instanceof GeoRegion) {
GeoRegion region = (GeoRegion) extent;
if (considerSegmentXRegion(seg, region)) {
collector.collect(seg, region);
}
} else if (extent instanceof GeoPath) {
GeoPath p = (GeoPath) extent;
if (isSegmentNearPoly(seg, p.getPoints(), filter.getHRange()) != null) {
collector.collect(seg, p);
}
} else {
BoundingCircle bc = extent.getBoundingCircle();
if (isSegmentNearRadialRegion(seg, bc.getCenter(), bc.getRadius(), filter.getHRange())) {
collector.collect(seg, extent);
}
}
}
}
}
}
/**
* Puts the region in the Collector if it intersects with the path.
*
* @param path
* @param region
*/
public void considerPathXRegion(GeoPath path, GeoRegion region) {
for (GeoPath.SegmentIterator pit = path.segmentIterator(); pit.hasNext();) {
GeoSegment seg = pit.nextSegment();
if (filter.preConsider(seg, region) && considerSegmentXRegion(seg, region)) {
collector.collect(seg, region);
// For the default implementation, we just care about
// the first contact.
return;
}
}
}
/**
* Returns true if the segment intersects with the region. The range of the
* query is determined by the filter set on this Intersection object.
*
* @param seg
* @param region
* @return true if segment intersects region
*/
public boolean considerSegmentXRegion(GeoSegment seg, GeoRegion region) {
return region.isSegmentNear(seg, filter.getHRange());
}
/**
* Adds regions to the Collector if the GeoPoint p is on or in the regions
* of the Collection.
*
* @param p
* @param regions
*/
public void considerPointXRegions(GeoPoint p, Collection regions) {
Iterator rit;
if (regions instanceof ExtentIndex) {
rit = ((ExtentIndex) regions).iterator(p);
} else {
rit = regions.iterator();
}
while (rit.hasNext()) {
GeoExtent extent = (GeoExtent) rit.next();
if (filter.preConsider(p, extent)) {
if (extent instanceof GeoRegion) {
GeoRegion region = (GeoRegion) extent;
if (considerPointXRegion(p, region)) {
collector.collect(p, region);
}
} else if (extent instanceof GeoPath) {
GeoPath path = (GeoPath) extent;
if (isPointNearPoly(p.getPoint(), path.getPoints(), filter.getHRange())) {
collector.collect(p, path);
}
} else {
BoundingCircle bc = extent.getBoundingCircle();
if (p.getPoint().distance(bc.getCenter()) <= bc.getRadius() + filter.getHRange()) {
collector.collect(p, extent);
}
}
}
}
}
/**
* @param p
* @param region
* @return true if p is in region.
*/
public boolean considerPointXRegion(GeoPoint p, GeoRegion region) {
return isPointInPolygon(p.getPoint(), region.getPoints());
}
//
// Static versions of intersection methods
//
/**
* Simplified version of #intersect(Path, Collection, Algorithm) for old
* code, using the default match algorithm, and returning the identifiers of
* the regions that intersect with the path.
*
* @param path
* @param regions
* @return an iterator over list of the intersecting regions.
*/
public static Iterator intersect(Object path, Object regions) {
MatchCollector.SetMatchCollector c = new MatchCollector.SetMatchCollector();
Intersection ix = new Intersection(new MatchFilter.MatchParametersMF(MatchParameters.STRICT), c);
ix.consider(path, regions);
return c.iterator();
}
//
// Utility methods (The Mathematics)
//
/**
* Returns the two antipodal points of intersection of two great circles
* defined by the arcs (lat1, lon1) to (lat2, lon2) and (lat2, lon2) to
* (lat4, lon4). All lat-lon values are in degrees.
*
* @return an array of two lat-lon points arranged as lat, lon, lat, lon
*/
public static float[] getIntersection(float lat1, float lon1, float lat2, float lon2, float lat3, float lon3, float lat4,
float lon4) {
Geo geoCross1 = (new Geo(lat1, lon1)).crossNormalize(new Geo(lat2, lon2));
Geo geoCross2 = (new Geo(lat3, lon3)).crossNormalize(new Geo(lat4, lon4));
Geo geo = geoCross1.crossNormalize(geoCross2);
Geo anti = geo.antipode();
return new float[] {
((float) geo.getLatitude()),
((float) geo.getLongitude()),
((float) anti.getLatitude()),
((float) anti.getLongitude())
};
}
/**
* Returns the two antipodal points of intersection of two great circles
* defined by the arcs (lat1, lon1) to (lat2, lon2) and (lat2, lon2) to
* (lat4, lon4). All lat-lon values are in degrees.
*
* @return an array of two lat-lon points arranged as lat, lon, lat, lon
*/
public static double[] getIntersection(double lat1, double lon1, double lat2, double lon2, double lat3, double lon3,
double lat4, double lon4) {
Geo geoCross1 = (new Geo(lat1, lon1)).crossNormalize(new Geo(lat2, lon2));
Geo geoCross2 = (new Geo(lat3, lon3)).crossNormalize(new Geo(lat4, lon4));
Geo geo = geoCross1.crossNormalize(geoCross2);
Geo anti = geo.antipode();
return new double[] {
geo.getLatitude(),
geo.getLongitude(),
anti.getLatitude(),
anti.getLongitude()
};
}
/**
* Returns a Geo representing the intersection of two great circles defined
* by the arcs (lat1, lon1) to (lat2, lon2) and (lat2, lon2) to (lat4,
* lon4). All lat-lon values are in degrees.
*
* @return Geo containing intersection, might have to check antipode of Geo
* for actual intersection.
*/
public static Geo getIntersectionGeo(double lat1, double lon1, double lat2, double lon2, double lat3, double lon3, double lat4,
double lon4) {
Geo geoCross1 = (new Geo(lat1, lon1)).crossNormalize(new Geo(lat2, lon2));
Geo geoCross2 = (new Geo(lat3, lon3)).crossNormalize(new Geo(lat4, lon4));
// geoCross memory is reused for answer.
return geoCross1.crossNormalize(geoCross2, geoCross1);
}
/**
* Returns true if the two segs intersect in at least one point. All lat-lon
* values are in degrees. lat1,lon1-lat2,lon2 make up one segment,
* lat3,lon3-lat4,lon4 make up the other segment.
*/
public static boolean intersects(double lat1, double lon1, double lat2, double lon2, double lat3, double lon3, double lat4,
double lon4) {
double[] llp = getSegIntersection(lat1, lon1, lat2, lon2, lat3, lon3, lat4, lon4);
return (llp[0] != Double.MAX_VALUE && llp[1] != Double.MAX_VALUE)
|| (llp[2] != Double.MAX_VALUE && llp[3] != Double.MAX_VALUE);
}
/**
* Checks if the two polygonal areas intersect. The two polygonal regions
* are represented by two lat-lon arrays in the lat1, lon1, lat2, lon2,...
* format. For closed polygons the last pair of points in the array should
* be the same as the first pair. All lat-lon values are in degrees.
*/
public static boolean polyIntersect(float[] polyPoints1, float[] polyPoints2) {
// go through each side of poly1 and test to see if it
// intersects with any side of poly2
for (int i = 0; i < polyPoints1.length / 2 - 1; i++) {
for (int j = 0; j < polyPoints2.length / 2 - 1; j++) {
if (intersects(polyPoints1[2 * i], polyPoints1[2 * i + 1], polyPoints1[2 * i + 2], polyPoints1[2 * i + 3],
polyPoints2[2 * j], polyPoints2[2 * j + 1], polyPoints2[2 * j + 2], polyPoints2[2 * j + 3]))
return true;
}
}
return false;
}
/**
* Checks if the two polygonal areas intersect. The two polygonal regions
* are represented by two lat-lon arrays in the lat1, lon1, lat2, lon2,...
* format. For closed polygons the last pair of points in the array should
* be the same as the first pair. All lat-lon values are in degrees.
*/
public static boolean polyIntersect(double[] polyPoints1, double[] polyPoints2) {
// go through each side of poly1 and test to see if it
// intersects with any side of poly2
for (int i = 0; i < polyPoints1.length / 2 - 1; i++) {
for (int j = 0; j < polyPoints2.length / 2 - 1; j++) {
if (intersects(polyPoints1[2 * i], polyPoints1[2 * i + 1], polyPoints1[2 * i + 2], polyPoints1[2 * i + 3],
polyPoints2[2 * j], polyPoints2[2 * j + 1], polyPoints2[2 * j + 2], polyPoints2[2 * j + 3]))
return true;
}
}
return false;
}
/**
* Checks if the two polygonal areas intersect. The two polygonal regions
* are represented by two lat-lon arrays in the lat1, lon1, lat2, lon2,...
* format. For closed polygons the last pair of points in the array should
* be the same as the first pair. All lat-lon values are in degrees. KM
* optimized to create each Geo only once. (TODO consider optimizing the
* other paths.)
*/
public static boolean polyIntersect_optimized(double[] polyPoints1, double[] polyPoints2) {
// go through each side of poly1 and test to see if it
// intersects with any side of poly2
Geo geos1[] = new Geo[polyPoints1.length / 2];
Geo geos2[] = new Geo[polyPoints2.length / 2];
for (int i = 0; i < geos1.length; i++) {
geos1[i] = new Geo(polyPoints1[2 * i], polyPoints1[2 * i + 1]);
}
for (int i = 0; i < geos2.length; i++) {
geos2[i] = new Geo(polyPoints2[2 * i], polyPoints2[2 * i + 1]);
}
for (int i = 0; i < geos1.length - 1; i++) {
for (int j = 0; j < geos2.length - 1; j++) {
Geo p1 = geos1[i];
Geo p2 = geos1[i + 1];
Geo p3 = geos2[j];
Geo p4 = geos2[j + 1];
Geo[] results = getSegIntersection(p1, p2, p3, p4);
if (results[0] != null || results[1] != null) {
return true;
}
}
}
return false;
}
/**
* checks if the polygon or polyline represented by the polypoints contains
* any lines that intersect each other. All lat-lon values are in degrees.
*/
public static boolean isSelfIntersectingPoly(float[] polyPoints) {
for (int i = 0; i < polyPoints.length / 2 - 1; i++) {
for (int j = i + 1; j < polyPoints.length / 2 - 1; j++) {
float lat1 = polyPoints[2 * i];
float lon1 = polyPoints[2 * i + 1];
float lat2 = polyPoints[2 * i + 2];
float lon2 = polyPoints[2 * i + 3];
float lat3 = polyPoints[2 * j];
float lon3 = polyPoints[2 * j + 1];
float lat4 = polyPoints[2 * j + 2];
float lon4 = polyPoints[2 * j + 3];
// ignore adjacent segments
if ((lat1 == lat4 && lon1 == lon4) || (lat2 == lat3 && lon2 == lon3))
continue;
if (intersects(lat1, lon1, lat2, lon2, lat3, lon3, lat4, lon4))
return true;
}
}
return false;
}
/**
* checks if the polygon or polyline represented by the polypoints contains
* any lines that intersect each other. All lat-lon values are in degrees.
*/
public static boolean isSelfIntersectingPoly(double[] polyPoints) {
for (int i = 0; i < polyPoints.length / 2 - 1; i++) {
for (int j = i + 1; j < polyPoints.length / 2 - 1; j++) {
double lat1 = polyPoints[2 * i];
double lon1 = polyPoints[2 * i + 1];
double lat2 = polyPoints[2 * i + 2];
double lon2 = polyPoints[2 * i + 3];
double lat3 = polyPoints[2 * j];
double lon3 = polyPoints[2 * j + 1];
double lat4 = polyPoints[2 * j + 2];
double lon4 = polyPoints[2 * j + 3];
// ignore adjacent segments
if ((lat1 == lat4 && lon1 == lon4) || (lat2 == lat3 && lon2 == lon3))
continue;
if (intersects(lat1, lon1, lat2, lon2, lat3, lon3, lat4, lon4))
return true;
}
}
return false;
}
/**
* Calculates the great circle distance from the point (lat, lon) to the
* great circle containing the points (lat1, lon1) and (lat2, lon2).
*
* @return nautical miles
*/
public static double pointCircleDistanceNM(Geo p1, Geo p2, Geo center) {
return Geo.nm(pointCircleDistance(p1, p2, center));
}
/**
* Calculates the great circle distance from the point (center) to the
* great circle containing the points (p1) and (p2).
*
* @return radians
*/
public static double pointCircleDistance(Geo p1, Geo p2, Geo center) {
Geo n = Geo.crossNormalize(p1, p2, new Geo());
Geo c = center.normalize(new Geo());
double cosTheta = Geo.dot(n, c);
double theta = Math.acos(cosTheta);
return Math.abs(Math.PI / 2 - theta);
}
/**
* Point i is on the great circle defined by the points a and b. Returns
* true if i is between a and b, false otherwise. NOTE: i is assumed to be
* on the great circle line.
*/
public static boolean isOnSegment(Geo a, Geo b, Geo i) {
// assert (< (Math.abs (.dot (.crossNormalize a b) i))
// 1.e-15))
return ((a.distance(i) < a.distance(b)) && (b.distance(i) < b.distance(a)));
}
/**
* Returns true if i is on the great circle between a and b and between
* them, false otherwise. In other words, this method does the great circle
* test for you, too.
*/
public static boolean isOnSegment(Geo a, Geo b, Geo i, double withinRad) {
// assert (< (Math.abs (.dot (.crossNormalize a b) i))
// 1.e-15))
return ((Math.abs(a.crossNormalize(b).dot(i)) <= withinRad) && (a.distance(i) < a.distance(b)) && (b.distance(i) < b.distance(a)));
}
/**
* @return the Geo point i, which is on the great circle segment between Geo
* points a and b and which is closest to Geo point c. Returns null
* if there is no such point.
*/
public static Geo segIntersection(Geo a, Geo b, Geo c) {
// Normal to great circle between a and b
Geo g = a.crossNormalize(b);
// Normal to the great circle between c and g
Geo f = c.crossNormalize(g);
// The intersection is normal to both, reusing g object for it's memory.
Geo i = f.crossNormalize(g, g);
if (isOnSegment(a, b, i)) {
return i;
} else {
// reuse i object memory
Geo ai = i.antipode(i);
if (isOnSegment(a, b, ai)) {
return ai;
} else {
return null;
}
}
}
/**
* Test if [p1-p2] and [p3-p4] intersect
*/
public static final boolean segIntersects(Geo p1, Geo p2, Geo p3, Geo p4) {
Geo[] r = getSegIntersection(p1, p2, p3, p4);
return (r[0] != null || r[1] != null);
}
/**
* returns the distance in NM between the point (lat, lon) and the point of
* intersection of the great circle passing through (lat, lon) and
* perpendicular to great circle segment (lat1, lon1, lat2, lon2). returns
* -1 if point of intersection of the two great circle segs is not on the
* great circle segment (lat1, lon1, lat2, lon2).
*/
public static double pointSegDistanceNM(double lat1, double lon1, double lat2, double lon2, double lat, double lon) {
double ret = pointSegDistance(new Geo(lat1, lon1), new Geo(lat2, lon2), new Geo(lat, lon));
return (ret == -1 ? ret : Geo.nm(ret));
}
/**
* Returns the distance in radians between the point c and the point of
* intersection of the great circle passing through c and perpendicular to
* great circle segment between a and b. Returns -1 if point of intersection
* of the two great circle segs is not on the great circle segment a-b.
*/
public static double pointSegDistance(Geo a, Geo b, Geo c) {
Geo i = segIntersection(a, b, c);
return (i == null) ? -1 : c.distance(i);
}
/**
* Returns true or false depending on whether the great circle seg from
* point p1 to point p2 intersects the circle of radius (radians) around
* center.
*/
public static boolean intersectsCircle(Geo p1, Geo p2, Geo center, double radius) {
// check if either of the end points of the seg are inside the
// circle
double d1 = Geo.distance(p1, center);
if (d1 < radius)
return true;
double d2 = Geo.distance(p2, center);
if (d2 < radius)
return true;
double dist = pointCircleDistance(p1, p2, center);
if (dist > radius)
return false;
// calculate point of intersection of great circle containing
// (lat, lon) and perpendicular to great circle containing
// (lat1, lon1) and (lat2, lon2)
Geo g = p1.cross(p2);
Geo f = center.cross(g);
// Reusing g object for i
Geo i = f.crossNormalize(g, g);
// check if point of intersection lies on the segment
// length of seg
double d = Geo.distance(p1, p2);
// Make sure the intersection point is inside the exclusion
// zone
if (center.distance(i) < radius) {
// between seg endpoints and first point of intersection
double d11 = Geo.distance(p1, i);
double d12 = Geo.distance(p2, i);
// Check the distance of the intersection point and either
// endpoint to see if it falls between them. Add a second
// test to make sure that we are on the shorter of the two
// segments between the endpoints.
return (d11 <= d && d12 <= d && Math.abs(d11 + d12 - d) < 0.01f);
}
// Make sure the intersection point is inside the exclusion
// zone, reusing i object for i2
Geo i2 = i.antipode(i);
if (center.distance(i2) < radius) {
// between seg1 endpoints and second point of intersection
double d21 = Geo.distance(p1, i2);
double d22 = Geo.distance(p2, i2);
// Check the distance of the intersection point and either
// endpoint to see if it falls between them. Add a second
// test to make sure that we are on the shorter of the two
// segments between the endpoints.
return (d21 <= d && d22 <= d && Math.abs(d21 + d22 - d) < 0.01f);
}
return false;
}
/**
* returns true if the specified poly path intersects the circle centered at
* (lat, lon). All lat-lon values are in degrees. radius is in radians.
*/
public static boolean intersectsCircle(float[] polyPoints, double lat, double lon, double radius) {
Geo a = new Geo(polyPoints[0], polyPoints[1]);
Geo b = new Geo();
Geo c = new Geo(lat, lon);
int numCoords = polyPoints.length / 2 - 1;
for (int i = 1; i < numCoords; i++) {
float lat2 = polyPoints[2 * i];
float lon2 = polyPoints[2 * i + 1];
b.initialize(lat2, lon2);
if (intersectsCircle(a, b, c, radius))
return true;
a.initialize(b);
}
return false;
}
/**
* returns true if the specified poly path intersects the circle centered at
* (lat, lon). All lat-lon values are in degrees. radius is in radians.
*/
public static boolean intersectsCircle(double[] polyPoints, double lat, double lon, double radius) {
Geo a = new Geo(polyPoints[0], polyPoints[1]);
Geo b = new Geo();
Geo c = new Geo(lat, lon);
int numCoords = polyPoints.length / 2 - 1;
for (int i = 1; i < numCoords; i++) {
double lat2 = polyPoints[2 * i];
double lon2 = polyPoints[2 * i + 1];
b.initialize(lat2, lon2);
if (intersectsCircle(a, b, c, radius))
return true;
a.initialize(b);
}
return false;
}
/**
* Returns the center of the polygon poly.
*/
public static Geo center(Geo[] poly) {
return center(poly, new Geo());
}
/**
* Returns the center of the polygon poly.
*/
public static Geo center(Geo[] poly, Geo ret) {
Geo c = new Geo(poly[0]);
for (int i = 1; i < poly.length; i++) {
ret.initialize(poly[i]);
c = c.add(poly[i], c);
}
return c.normalize(ret);
}
/**
* Returns the center of the polygon poly.
*/
public static Geo center(GeoArray poly) {
return center(poly, new Geo());
}
/**
* Returns the center of the polygon poly.
*
* @param poly the GeoArray of the polygon
* @param ret a Geo to use for the return values.
* @return ret.
*/
public static Geo center(GeoArray poly, Geo ret) {
Geo c = poly.get(0, new Geo());
int size = poly.getSize();
for (int i = 1; i < size; i++) {
poly.get(i, ret);
c = c.add(ret, c);
}
return c.normalize(ret);
}
/**
* Determines whether <code>x</code> is inside <code>poly</code>.
*
* <p>
* <em>N.B.</em><br>
* <ul>
* <li><code>poly</code> must be a closed polygon. In other words, the first
* and last point must be the same.
* <li>It is recommended that a bounds check is run before this method. This
* method will return true if either <code>x</code> or the antipode (the
* point on the opposite side of the planet) of <code>x</code> are inside
* <code>poly</code>.
* </ul>
*
* <p>
* <code>poly</code> is an array of latitude/longitude points where:
* <br>
* <pre>
*
*
* poly[0] = latitude 1
* poly[1] = longitude 1
* poly[2] = latitude 2
* poly[3] = longitude 2
* .
* .
* .
* poly[n-1] = latitude 1
* poly[n] = longitude 1
*
* </pre>
*
* @param x a geographic coordinate
* @param poly an array of lat/lons describing a closed polygon
* @return true iff <code>x</code> or <code>antipode(x)</code> is inside
* <code>poly</code>
*/
public static boolean isPointInPolygon(Geo x, GeoArray poly) {
Geo c = center(poly, new Geo());
// bail out if the point is more than 90 degrees off the
// centroid
double d = x.distance(c);
if (d >= (Math.PI / 2)) {
return false;
}
// ray is normal to the great circle from c to x. reusing c to hold ray
// info
Geo ray = c.crossNormalize(x, c);
/*
* side is a point on the great circle between c and x. It is used to
* choose a direction.
*/
Geo side = x.crossNormalize(ray, new Geo());
boolean in = false;
// Why do we need to allocate new Geos?
// Geo p1 = new Geo(poly[0]);
// Geo p2 = new Geo(poly[0]);
Geo p1 = poly.get(0, new Geo());
Geo p2 = poly.get(0, new Geo());
Geo tmp = new Geo();
int polySize = poly.getSize();
for (int i = 1; i < polySize; i++) {
// p2.initialize(poly[i]);
p2 = poly.get(i, p2);
/*
* p1 and p2 are on different sides of the ray, and the great
* acircle between p1 and p2 is on the side that counts;
*/
if ((p1.dot(ray) < 0.0) != (p2.dot(ray) < 0.0) && p1.intersect(p2, ray, tmp).dot(side) > 0.0) {
in = !in;
}
p1.initialize(p2);
}
// Check for unclosed polygons, if the polygon isn't closed,
// do the calculation for the last point to the starting
// point.
if (!poly.equals(0, p1)) {
poly.get(0, p2);
if ((p1.dot(ray) < 0.0) != (p2.dot(ray) < 0.0) && p1.intersect(p2, ray, tmp).dot(side) > 0.0) {
in = !in;
}
}
return in;
}
public static boolean isPointInPolygon(Geo x, GeoArray poly, Geo internal) {
Geo c = Geo.makeGeo(internal);
// bail out if the point is more than 90 degrees off the
// centroid
double d = x.distance(c);
if (d >= (Math.PI / 2)) {
return false;
}
if (internal.equals(c))
return true;
// ray is normal to the great circle from c to x. reusing c to hold ray
// info
Geo ray = c.crossNormalize(x, c);
/*
* side is a point on the great circle between c and x. It is used to
* choose a direction.
*/
Geo side = x.crossNormalize(ray, new Geo());
boolean in = false;
// Why do we need to allocate new Geos?
// Geo p1 = new Geo(poly[0]);
// Geo p2 = new Geo(poly[0]);
Geo p1 = poly.get(0, new Geo());
Geo p2 = poly.get(0, new Geo());
Geo tmp = new Geo();
int polySize = poly.getSize();
for (int i = 1; i < polySize; i++) {
// p2.initialize(poly[i]);
p2 = poly.get(i, p2);
/*
* p1 and p2 are on different sides of the ray, and the great
* acircle between p1 and p2 is on the side that counts;
*/
if ((p1.dot(ray) < 0.0) != (p2.dot(ray) < 0.0) && p1.intersect(p2, ray, tmp).dot(side) > 0.0)
in = !in;
p1.initialize(p2);
}
// Check for unclosed polygons, if the polygon isn't closed,
// do the calculation for the last point to the starting
// point.
if (!poly.equals(0, p1)) {
poly.get(0, p2);
if ((p1.dot(ray) < 0.0) != (p2.dot(ray) < 0.0) && p1.intersect(p2, ray, tmp).dot(side) > 0.0) {
in = !in;
}
}
return in;
}
/**
* Ask if a Geo point is in a polygon.
*
* @param x
* @param poly double array where [lat, lon, lat, lon,...]
* @param polyInDegrees true of poly floats represent decimal degrees.
* @return true for Geo in poly
*/
public static boolean isPointInPolygon(Geo x, double[] poly, boolean polyInDegrees) {
if (polyInDegrees) {
return isPointInPolygon(x, GeoArray.Float.createFromLatLonDegrees(poly));
} else {
return isPointInPolygon(x, GeoArray.Float.createFromLatLonRadians(poly));
}
}
/**
* Ask if a Geo point is in a polygon.
*
* @param x
* @param poly float array where [lat, lon, lat, lon,...]
* @param polyInDegrees true of poly floats represent decimal degrees.
* @return true for Geo in poly
*/
public static boolean isPointInPolygon(Geo x, float[] poly, boolean polyInDegrees) {
if (polyInDegrees) {
return isPointInPolygon(x, GeoArray.Float.createFromLatLonDegrees(poly));
} else {
return isPointInPolygon(x, GeoArray.Float.createFromLatLonRadians(poly));
}
}
/**
* return true IFF some point of the first argument is inside the region
* specified by the closed polygon specified by the second argument
*/
public static boolean isPolylineInsidePolygon(GeoArray poly, GeoArray region) {
int polySize = poly.getSize();
Geo testPoint = new Geo();
for (int i = 0; i < polySize; i++) {
poly.get(i, testPoint);
if (isPointInPolygon(testPoint, region)) {
return true;
}
}
return false;
}
/**
* Returns the point of intersection of two great circle segments defined by
* the segments. (lat1, lon1) to (lat2, lon2) and (lat2, lon2) to (lat4,
* lon4). All lat-lon values are in degrees.
*
* @return a float array of length 4 containing upto 2 valid lat-lon points
* of intersection that lie on both segments. Positions in the array
* not containing a valid lat/lon value are initialized to
* Float.MAX_VALUE.
*/
public static double[] getSegIntersection(double lat1, double lon1, double lat2, double lon2, double lat3, double lon3,
double lat4, double lon4) {
// KRA 03SEP03: The original version of this consed 26+ Geo's.
// This one conses 8+. WAIT! Now it uses 6
Geo p1 = new Geo(lat1, lon1);
Geo p2 = new Geo(lat2, lon2);
Geo p3 = new Geo(lat3, lon3);
Geo p4 = new Geo(lat4, lon4);
Geo[] results = getSegIntersection(p1, p2, p3, p4);
Geo i1 = results[0];
Geo i2 = results[1];
double[] llp = new double[] {
Double.MAX_VALUE,
Double.MAX_VALUE,
Double.MAX_VALUE,
Double.MAX_VALUE
};
// check if first point of intersection lies on both segments
if (i1 != null) {
llp[0] = i1.getLatitude();
llp[1] = i1.getLongitude();
}
// check if second point of intersection lies on both segments
if (i2 != null) {
llp[2] = i2.getLatitude();
llp[3] = i2.getLongitude();
}
return llp;
}
/**
* Find the intersection(s) between [p1-p2] and [p3-p4]
*/
public static final Geo[] getSegIntersection(Geo p1, Geo p2, Geo p3, Geo p4) {
Geo geoCross1 = p1.crossNormalize(p2);
Geo geoCross2 = p3.crossNormalize(p4);
// i1 is really geoCross1, i2 is really geoCross2, memory-wise.
Geo i1 = geoCross1.crossNormalize(geoCross2, geoCross1);
Geo i2 = i1.antipode(geoCross2);
// check if the point of intersection lies on both segs
// length of seg1
double d1 = p1.distance(p2);
// length of seg2
double d2 = p3.distance(p4);
// between seg1 endpoints and first point of intersection
double d111 = p1.distance(i1);
double d121 = p2.distance(i1);
// between seg1 endpoints and second point of intersection
double d112 = p1.distance(i2);
double d122 = p2.distance(i2);
// between seg2 endpoints and first point of intersection
double d211 = p3.distance(i1);
double d221 = p4.distance(i1);
// between seg2 endpoints and second point of intersection
double d212 = p3.distance(i2);
double d222 = p4.distance(i2);
Geo[] result = new Geo[] {
null,
null
};
// check if first point of intersection lies on both segments
if (d1 >= d111 && d1 >= d121 && d2 >= d211 && d2 >= d221) {
result[0] = i1;
}
// check if second point of intersection lies on both segments
if (d1 >= d112 && d1 >= d122 && d2 >= d212 && d2 >= d222) {
result[1] = i2;
}
return result;
}
// /**
// * returns the point of intersection of two great circle segments
// * defined by the segments. (lat1, lon1) to (lat2, lon2) and
// * (lat2, lon2) to (lat4, lon4). All lat-lon values are in
// * degrees.
// *
// * @return a float array of length 4 containing upto 2 valid
// * lat-lon points of intersection that lie on both
// * segments. Positions in the array not containing a valid
// * lat/lon value are initialized to Float.MAX_VALUE.
// */
// public static float[] getSegIntersectionOrig(float lat1, float
// lon1,
// float lat2, float lon2,
// float lat3, float lon3,
// float lat4, float lon4) {
// // KRA 03SEP03: We can do better than this.
//
// float[] ll = getIntersection(lat1,
// lon1,
// lat2,
// lon2,
// lat3,
// lon3,
// lat4,
// lon4);
//
// // check if the point of intersection lies on both segs
//
// // length of seg1
// double d1 = Geo.distance(lat1, lon1, lat2, lon2);
// // length of seg2
// double d2 = Geo.distance(lat3, lon3, lat4, lon4);
//
// // between seg1 endpoints and first point of intersection
// double d111 = Geo.distance(lat1, lon1, ll[0], ll[1]);
// double d121 = Geo.distance(lat2, lon2, ll[0], ll[1]);
//
// // between seg1 endpoints and second point of intersection
// double d112 = Geo.distance(lat1, lon1, ll[2], ll[3]);
// double d122 = Geo.distance(lat2, lon2, ll[2], ll[3]);
//
// // between seg2 endpoints and first point of intersection
// double d211 = Geo.distance(lat3, lon3, ll[0], ll[1]);
// double d221 = Geo.distance(lat4, lon4, ll[0], ll[1]);
//
// // between seg2 endpoints and second point of intersection
// double d212 = Geo.distance(lat3, lon3, ll[2], ll[3]);
// double d222 = Geo.distance(lat4, lon4, ll[2], ll[3]);
//
// float[] llp = new float[] { Float.MAX_VALUE, Float.MAX_VALUE,
// Float.MAX_VALUE, Float.MAX_VALUE };
//
// // check if first point of intersection lies on both segments
// if (d1 >= d111 && d1 >= d121 && d2 >= d211 && d2 >= d221) {
// llp[0] = ll[0];
// llp[1] = ll[1];
// }
//
// // check if second point of intersection lies on both segments
// if (d1 >= d112 && d1 >= d122 && d2 >= d212 && d2 >= d222) {
// llp[2] = ll[2];
// llp[3] = ll[3];
// }
//
// return llp;
// }
/**
* Does the segment come within near radians of the region defined by
* rCenter at rRadius?
*/
public static final boolean isSegmentNearRadialRegion(GeoSegment segment, Geo rCenter, double rRadius, double near) {
Geo[] s = segment.getSeg();
if (s != null && s.length == 2) {
return isSegmentNearRadialRegion(s[0], s[1], rCenter, rRadius, near);
}
return false;
}
/**
* Does the segment come within near radians of the region defined by
* rCenter at rRadius?
*/
public static final boolean isSegmentNearRadialRegion(Geo s1, Geo s2, Geo rCenter, double rRadius, double near) {
return s1.isInside(s2, near + rRadius, rCenter);
}
/** Is a segment horizontally within range of a Region region? */
public static final boolean isSegmentNearRegion(GeoSegment segment, double hrange, GeoRegion region) {
// Need to be careful here - calling
// region.isSegmentNear(segment, hrange) can result in
// circular code if the region just calls this method, which
// may seem reasonable, if you look at the API.
return isSegmentNearPolyRegion(segment, region.getPoints(), hrange);
}
/**
* Does the segment come within near radians of the region defined by the
* polygon in r[*]? Catches segments within poly region and returns after
* first hit, which is why it returns boolean.
*/
public static final boolean isSegmentNearPolyRegion(GeoSegment segment, GeoArray r, double near) {
Geo[] s = segment.getSeg();
if (s != null && s.length == 2) {
return isSegmentNearPolyRegion(s[0], s[1], r, near);
}
return false;
}
/**
* Does the segment s1-s2 come within near radians of the region defined by
* the polygon in r[*]? Catches segments within poly region and returns
* after first hit, which is why it returns boolean.
*/
public static final boolean isSegmentNearPolyRegion(Geo s1, Geo s2, GeoArray r, double near) {
return isSegmentNearPoly(s1, s2, r, near) != null || isPointInPolygon(s1, r);
}
/**
* Where is a segment within range of a region?
*/
public static final Geo isSegmentNearPoly(GeoSegment segment, GeoArray r, double near) {
Geo[] s = segment.getSeg();
if (s != null && s.length == 2) {
return isSegmentNearPoly(s[0], s[1], r, near);
}
return null;
}
/**
* Is a segment, represented by endpoints 's1' and 's2', withing a range
* 'near' of region 'r'?
*
* @param s1 Endpoint of segment
* @param s2 Endpoint of segment
* @param r Region of interest
* @param near acceptable range between the segment and region, in radians.
* @return Geo location where the condition was initially met (yes), null if
* conditions weren't met (no).
*/
public static final Geo isSegmentNearPoly(Geo s1, Geo s2, GeoArray r, double near) {
int rlen = r.getSize();
Geo pl0 = r.get(rlen - 1, new Geo());
Geo pl1 = new Geo();
// check will be returned as ret, but we only allocate one per this
// method call, instead of one per loop, since we are returning if ret
// is not null.
Geo check = new Geo();
for (int j = 0; j < rlen; j++) {
pl1 = r.get(j, pl1);
Geo ret = segmentsIntersectOrNear(s1, s2, pl0, pl1, near, check);
if (ret != null) {
return ret;
}
pl0.initialize(pl1);
}
return null;
}
/**
* Where is a segment within range of a region?
*/
public static final List<Geo> segmentNearPoly(GeoSegment segment, GeoArray r, double near) {
Geo[] s = segment.getSeg();
List<Geo> list = null;
if (s != null && s.length == 2) {
list = segmentNearPoly(s[0], s[1], r, near);
}
return list;
}
/**
* Where is a segment, represented by endpoints 's1' and 's2', withing a
* range 'near' of region 'r'?
*
* @param s1 Endpoint of segment
* @param s2 Endpoint of segment
* @param r Region of interest
* @param near acceptable range between the segment and region, in radians.
* @return Geo location where the condition was met (yes), null if
* conditions weren't met (no).
*/
public static final List<Geo> segmentNearPoly(Geo s1, Geo s2, GeoArray r, double near) {
int rlen = r.getSize();
Geo pl0 = r.get(rlen - 1, new Geo());
Geo pl1 = new Geo();
List<Geo> list = null;
Geo check = new Geo();
for (int j = 0; j < rlen; j++) {
r.get(j, pl1);
Geo ret = segmentsIntersectOrNear(s1, s2, pl0, pl1, near, check);
if (ret != null) {
if (list == null) {
list = new LinkedList<Geo>();
}
list.add(ret);
// ret is actually the last created check. This mechanism limits
// the creation of Geos to only hits + 1.
check = new Geo();
}
pl0.initialize(pl1);
}
return list;
}
/**
* Does the point s come within 'near' radians of the boarder of the region
* defined by the polygon in r[*]?
*/
public static final boolean isPointNearPoly(Geo s, GeoArray r, double near) {
int rlen = r.getSize();
Geo pl0 = r.get(rlen - 1, new Geo());
Geo pl1 = new Geo();
for (int j = 0; j < rlen; j++) {
r.get(j, pl1);
if (pl0.isInside(pl1, near, s)) {
return true; // near enough to a region edge
}
pl0.initialize(pl1);
}
return false;
}
/**
* Is one region's boundary within 'near' range of a region? Note: good
* practice is s describes a smaller area than r.
*
* @return the Geo location where the condition was first met, null if the
* condition wasn't met.
*/
public static final Geo isPolyNearPoly(GeoArray s, GeoArray r, double near) {
int rlen = r.getSize();
int slen = s.getSize();
Geo pl0 = r.get(rlen - 1);
Geo pl1 = new Geo();
Geo sl0 = s.get(slen - 1);
Geo sl1 = new Geo();
for (int j = 0; j < rlen; j++) {
pl1 = r.get(j, pl1);
for (int i = 0; i < slen; i++) {
sl1 = s.get(i, sl1);
Geo ret = segmentsIntersectOrNear(sl0, sl1, pl0, pl1, near);
if (ret != null) {
return ret;
}
sl0 = sl1;
}
pl0 = pl1;
}
return null;
}
/**
* Is one region's boundary within 'near' range of a region? Note: good
* practice is s describes a smaller area than r.
*
* @return a List where the polys intersect within the range, null if the
* condition wasn't met.
*/
public static final List<Geo> polyNearPoly(GeoArray s, GeoArray r, double near) {
int rlen = r.getSize();
int slen = s.getSize();
Geo pl0 = r.get(rlen - 1);
Geo pl1 = new Geo();
Geo sl0 = s.get(slen - 1);
Geo sl1 = new Geo();
List<Geo> list = null;
for (int j = 0; j < rlen; j++) {
pl1 = r.get(j, pl1);
for (int i = 0; i < slen; i++) {
sl1 = s.get(i, sl1);
Geo ret = segmentsIntersectOrNear(sl0, sl1, pl0, pl1, near);
if (ret != null) {
if (list == null) {
list = new LinkedList<Geo>();
}
list.add(ret);
}
sl0 = sl1;
}
pl0 = pl1;
}
return list;
}
/**
* @return a Geo location iff the great circle segments defined by a1-a2 and
* b1-b2 intersect. the angles between the segments must be < PI or
* the results are ambiguous.Returns null if the segments don't
* intersect within the range.
*/
public static Geo segmentsIntersect(Geo a1, Geo a2, Geo b1, Geo b2) {
return segmentsIntersectOrNear(a1, a2, b1, b2, 0);
}
/**
* @return a Geo location iff the great circle segments defined by a1-a2 and
* b1-b2 come within the range (r, radians) of each other. The
* angles between the segments must be < PI or the results are
* ambiguous. Returns null if the segments don't intersect within the
* range.
*/
public static Geo segmentsIntersectOrNear(Geo a1, Geo a2, Geo b1, Geo b2, double r) {
if (a1 == null || a2 == null || b1 == null || b2 == null) {
return null;
}
// ac and bc are the unit vectors normal to the two great
// circles defined by the segments
Geo ac = a1.crossNormalize(a2);
Geo bc = b1.crossNormalize(b2);
// aL and bL are the lengths (in radians) of the segments
double aL = a1.distance(a2) + r;
double bL = b1.distance(b2) + r;
// i is one of the two points where the two great circles
// intersect. Since we don't use bc anymore, let's reuse it for i, gets
// passed back from crossNormalize as the second argument.
Geo i = ac.crossNormalize(bc, bc);
// if i is not on A
if (!(i.distance(a1) <= aL && i.distance(a2) <= aL)) {
i = i.antipode(i); // switch to the antipode instead, reuse i
// object for new values.
if (!(i.distance(a1) <= aL && i.distance(a2) <= aL)) { // check
// again
// nope - neither i nor i' is on A, so we'll bail out
return null;
}
}
// i is intersection or anti-intersection point now.
// Now see if it intersects with b
if (i.distance(b1) <= bL && i.distance(b2) <= bL) {
return i;
} else {
return null;
}
}
/**
* @return a Geo location iff the great circle segments defined by a1-a2 and
* b1-b2 come within the range (r, radians) of each other. The
* angles between the segments must be < PI or the results are
* ambiguous. Returns null if the segments don't intersect within the
* range.
*/
public static Geo segmentsIntersectOrNear(Geo a1, Geo a2, Geo b1, Geo b2, double r, Geo ret) {
if (a1 == null || a2 == null || b1 == null || b2 == null) {
return null;
}
// ac and bc are the unit vectors normal to the two great
// circles defined by the segments. ret is returned from crossNormalize
// as bc.
Geo ac = a1.crossNormalize(a2);
Geo bc = b1.crossNormalize(b2, ret);
// aL and bL are the lengths (in radians) of the segments
double aL = a1.distance(a2) + r;
double bL = b1.distance(b2) + r;
// i is one of the two points where the two great circles
// intersect. Since we don't use bc anymore, let's reuse it for i, gets
// passed back from crossNormalize as the second argument.
Geo i = ac.crossNormalize(bc, bc);
// if i is not on A
if (!(i.distance(a1) <= aL && i.distance(a2) <= aL)) {
i = i.antipode(ret); // switch to the antipode instead, reuse ret
// yet again.
if (!(i.distance(a1) <= aL && i.distance(a2) <= aL)) { // check
// again
// nope - neither i nor i' is on A, so we'll bail out
return null;
}
}
// i is intersection or anti-intersection point now.
// Now see if it intersects with b
if (i.distance(b1) <= bL && i.distance(b2) <= bL) {
// remember ret -> bc -> i, so i == ret
return i;
} else {
return null;
}
}
public static void main(String[] args) {
/**
* Produces output: (1)=53.130104, -100.0 (2)=3.4028235E38,
* -3.4028235E38 intersects=true polyIntersect=true dist=655.4312
* b3=true
*/
double lat1 = 60;
double lon1 = -130;
double lat2 = 30;
double lon2 = -70;
double lat3 = 60;
double lon3 = -70;
double lat4 = 30;
double lon4 = -130;
double[] ll = getSegIntersection(lat1, -lon1, lat2, -lon2, lat3, -lon3, lat4, -lon4);
System.out.println("(1)=" + ll[0] + ", " + (-ll[1]));
System.out.println("(2)=" + ll[2] + ", " + (-ll[3]));
boolean b1 = intersects(lat1, -lon1, lat2, -lon2, lat3, -lon3, lat4, -lon4);
System.out.println("intersects=" + b1);
double[] polypoints1 = new double[] {
38,
-27,
-46,
165
};
double[] polypoints2 = new double[] {
51,
-42,
55,
-17,
11,
-23,
51,
-42
};
boolean b2 = polyIntersect(polypoints1, polypoints2);
System.out.println("polyIntersect=" + b2);
}
}