/* This program 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 3 of
the License, or (at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
package org.opentripplanner.common.geometry;
import org.opentripplanner.common.model.P2;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.CoordinateSequence;
import com.vividsolutions.jts.geom.CoordinateSequenceFactory;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.linearref.LengthLocationMap;
import com.vividsolutions.jts.linearref.LinearLocation;
import com.vividsolutions.jts.linearref.LocationIndexedLine;
public class GeometryUtils {
private static CoordinateSequenceFactory csf =
new Serializable2DPackedCoordinateSequenceFactory();
private static GeometryFactory gf = new GeometryFactory(csf);
public static LineString makeLineString(double... coords) {
GeometryFactory factory = getGeometryFactory();
Coordinate [] coordinates = new Coordinate[coords.length / 2];
for (int i = 0; i < coords.length; i+=2) {
coordinates[i / 2] = new Coordinate(coords[i], coords[i+1]);
}
return factory.createLineString(coordinates);
}
public static GeometryFactory getGeometryFactory() {
return gf;
}
/**
* Splits the input geometry into two LineStrings at the given point.
*/
public static P2<LineString> splitGeometryAtPoint(Geometry geometry, Coordinate nearestPoint) {
// An index in JTS can actually refer to any point along the line. It is NOT an array index.
LocationIndexedLine line = new LocationIndexedLine(geometry);
LinearLocation l = line.indexOf(nearestPoint);
LineString beginning = (LineString) line.extractLine(line.getStartIndex(), l);
LineString ending = (LineString) line.extractLine(l, line.getEndIndex());
return new P2<LineString>(beginning, ending);
}
/**
* Splits the input geometry into two LineStrings at a fraction of the distance covered.
*/
public static P2<LineString> splitGeometryAtFraction(Geometry geometry, double fraction) {
LineString empty = new LineString(null, gf);
Coordinate[] coordinates = geometry.getCoordinates();
CoordinateSequence sequence = gf.getCoordinateSequenceFactory().create(coordinates);
LineString total = new LineString(sequence, gf);
if (coordinates.length < 2) return new P2<LineString>(empty, empty);
if (fraction <= 0) return new P2<LineString>(empty, total);
if (fraction >= 1) return new P2<LineString>(total, empty);
double totalDistance = total.getLength();
double requestedDistance = totalDistance * fraction;
// An index in JTS can actually refer to any point along the line. It is NOT an array index.
LocationIndexedLine line = new LocationIndexedLine(geometry);
LinearLocation l = LengthLocationMap.getLocation(geometry, requestedDistance);
LineString beginning = (LineString) line.extractLine(line.getStartIndex(), l);
LineString ending = (LineString) line.extractLine(l, line.getEndIndex());
return new P2<LineString>(beginning, ending);
}
/**
* Returns the chunk of the given geometry between the two given coordinates.
*
* Assumes that "second" is after "first" along the input geometry.
*/
public static LineString getInteriorSegment(Geometry geomerty, Coordinate first,
Coordinate second) {
P2<LineString> splitGeom = GeometryUtils.splitGeometryAtPoint(geomerty, first);
splitGeom = GeometryUtils.splitGeometryAtPoint(splitGeom.second, second);
return splitGeom.first;
}
/**
* Adapted from com.vividsolutions.jts.geom.LineSegment
* Combines segmentFraction and projectionFactor methods.
*/
public static double segmentFraction(double x0, double y0, double x1, double y1,
double xp, double yp, double xscale) {
// Use comp.graphics.algorithms Frequently Asked Questions method
double dx = (x1 - x0) * xscale;
double dy = y1 - y0;
double len2 = dx * dx + dy * dy;
// this fixes a (reported) divide by zero bug in JTS when line segment has 0 length
if (len2 == 0)
return 0;
double r = ( (xp - x0) * xscale * dx + (yp - y0) * dy ) / len2;
if (r < 0.0)
return 0.0;
else if (r > 1.0)
return 1.0;
return r;
}
}