TracerGeometry.java

// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.plugins.tracer2;

import org.openstreetmap.josm.data.coor.LatLon;

public final class TracerGeometry {

    private TracerGeometry() {
        // Hide default constructor for utilities classes
    }

    /**
     * Angle between line AB and CD
     * @param a Point A.
     * @param b Point B.
     * @param c Point C.
     * @param d Point D.
     * @return Angle in degrees.
     */
    public static double angleOfLines(LatLon a, LatLon b, LatLon c, LatLon d) {
        return (Math.abs(
                Math.atan2(a.lat() - b.lat(), a.lon() - b.lon()) -
                Math.atan2(c.lat() - d.lat(), c.lon() - d.lon())
                ) / Math.PI * 180) % 360;
    }

    /**
     * Distance of point C from line segment AB.
     * @param c Point C.
     * @param a Point A.
     * @param b Point B.
     * @return Distance.
     */
    public static double distanceFromSegment(LatLon c, LatLon a, LatLon b) {
        return distanceFromSegment(
                c.getX(), c.getY(),
                a.getX(), a.getY(),
                b.getX(), b.getY()
                );
    }

    private static double distanceFromSegment(double cx, double cy, double ax, double ay, double bx, double by) {
        double r_numerator = (cx - ax) * (bx - ax) + (cy - ay) * (by - ay);
        double r_denomenator = (bx - ax) * (bx - ax) + (by - ay) * (by - ay);
        if (r_denomenator == 0)System.out.println("r_denomenator == 0    ------------");
        double r = r_numerator / r_denomenator;
        double s = ((ay - cy) * (bx - ax) - (ax - cx) * (by - ay)) / r_denomenator;
        double distanceLine = Math.abs(s) * Math.sqrt(r_denomenator);

        if ((r >= 0) && (r <= 1)) {
            return distanceLine;
        } else {
            double dist1 = (cx - ax) * (cx - ax) + (cy - ay) * (cy - ay);
            double dist2 = (cx - bx) * (cx - bx) + (cy - by) * (cy - by);
            if (dist1 < dist2) {
                return Math.sqrt(dist1);
            } else {
                return Math.sqrt(dist2);
            }
        }
    }
}