LocatePoint.java
- /**
- *
- */
- package org.opentrafficsim.road.network.factory.shape;
- import org.locationtech.jts.geom.Coordinate;
- import org.locationtech.jts.geom.LineString;
- /**
- * Computes the location of the point a given distance along a LineString
- */
- public class LocatePoint
- {
- public static Coordinate pointAlongSegment(Coordinate p0, Coordinate p1, double distance)
- {
- double segLen = p1.distance(p0);
- double frac = distance / segLen;
- if (frac <= 0.0)
- {
- return p0;
- }
- if (frac >= 1.0)
- {
- return p1;
- }
- double x = (p1.x - p0.x) * frac + p0.x;
- double y = (p1.y - p0.y) * frac + p0.y;
- return new Coordinate(x, y);
- }
- public static Coordinate pointAlongLine(LineString line, double distance)
- {
- LocatePoint loc = new LocatePoint(line, distance);
- return loc.getPoint();
- }
- private Coordinate pt;
- private int index;
- public LocatePoint(LineString line, double distance)
- {
- compute(line, distance);
- }
- private void compute(LineString line, double distance)
- {
- // <TODO> handle negative distances (measure from opposite end of line)
- double totalDist = 0.0;
- Coordinate[] coord = line.getCoordinates();
- for (int i = 0; i < coord.length - 1; i++)
- {
- Coordinate p0 = coord[i];
- Coordinate p1 = coord[i + 1];
- double segLen = p1.distance(p0);
- if (totalDist + segLen > distance)
- {
- pt = pointAlongSegment(p0, p1, distance - totalDist);
- index = i;
- return;
- }
- totalDist += segLen;
- }
- // distance is greater than line length
- pt = new Coordinate(coord[coord.length - 1]);
- index = coord.length;
- }
- public Coordinate getPoint()
- {
- return pt;
- }
- /**
- * Returns the index of the segment containing the computed point
- * @return the index
- */
- public int getIndex()
- {
- return index;
- }
- }