/*
* 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.algorithm.distance;
import com.vividsolutions.jts.geom.*;
/**
* Computes the Euclidean distance (L2 metric) from a Point to a Geometry.
* Also computes two points which are separated by the distance.
*/
public class DistanceToPoint {
// used for point-line distance calculation
private static LineSegment tempSegment = new LineSegment();
public DistanceToPoint() {
}
public static void computeDistance(Geometry geom, Coordinate pt, PointPairDistance ptDist)
{
if (geom instanceof LineString) {
computeDistance((LineString) geom, pt, ptDist);
}
else if (geom instanceof Polygon) {
computeDistance((Polygon) geom, pt, ptDist);
}
else if (geom instanceof GeometryCollection) {
GeometryCollection gc = (GeometryCollection) geom;
for (int i = 0; i < gc.getNumGeometries(); i++) {
Geometry g = gc.getGeometryN(i);
computeDistance(g, pt, ptDist);
}
}
else { // assume geom is Point
ptDist.setMinimum(geom.getCoordinate(), pt);
}
}
public static void computeDistance(LineString line, Coordinate pt, PointPairDistance ptDist)
{
Coordinate[] coords = line.getCoordinates();
for (int i = 0; i < coords.length - 1; i++) {
tempSegment.setCoordinates(coords[i], coords[i + 1]);
// this is somewhat inefficient - could do better
Coordinate closestPt = tempSegment.closestPoint(pt);
ptDist.setMinimum(closestPt, pt);
}
}
public static void computeDistance(LineSegment segment, Coordinate pt, PointPairDistance ptDist)
{
Coordinate closestPt = segment.closestPoint(pt);
ptDist.setMinimum(closestPt, pt);
}
public static void computeDistance(Polygon poly, Coordinate pt, PointPairDistance ptDist)
{
computeDistance(poly.getExteriorRing(), pt, ptDist);
for (int i = 0; i < poly.getNumInteriorRing(); i++) {
computeDistance(poly.getInteriorRingN(i), pt, ptDist);
}
}
}