Android Open Source - advanced-tourist-map Angle Calc

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License

The source code is released under:
GNU General Public License
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Java Source Code

/*
 * Copyright 2011 mapsforge.org//  w w  w  .j a v a  2 s . c  om
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU 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.muxe.advancedtouristmap.routing;

import org.mapsforge.core.Edge;
import org.mapsforge.core.GeoCoordinate;
import org.mapsforge.core.MercatorProjection;

/**
 * @author Eike Send
 */
public class AngleCalc {

  private static final int MIN_DISTANCE_TO_JUNCTION_FOR_ANGLE_MEASURING = 10;

  /**
   * Calculate the angle between two IEdge objects / streets
   * 
   * @param edge1
   *            the IEdge of the street before the crossing
   * @param edge2
   *            the IEdge of the street after the crossing
   * @return the angle between the given streets
   */
  public static double getAngleOfEdges(Edge edge1, Edge edge2) {
    if (edge1 != null && edge2 != null) {
      // Let's see if i can get the angle between the last street and this
      // This is the crossing
      GeoCoordinate crossingCoordinate = edge2.getAllWaypoints()[0];
      // The following is the last coordinate before the crossing
      GeoCoordinate coordinateBefore = edge1.getAllWaypoints()[edge1.getAllWaypoints().length - 2];
      // Take a coordinate further away from the crossing if it's too close
      if (coordinateBefore.sphericalDistance(crossingCoordinate) < MIN_DISTANCE_TO_JUNCTION_FOR_ANGLE_MEASURING
          && edge1.getAllWaypoints().length > 2) {
        coordinateBefore = edge1.getAllWaypoints()[edge1.getAllWaypoints().length - 3];
      }
      // Here comes the first coordinate after the crossing
      GeoCoordinate coordinateAfter = edge2.getAllWaypoints()[1];
      if (coordinateAfter.sphericalDistance(crossingCoordinate) < MIN_DISTANCE_TO_JUNCTION_FOR_ANGLE_MEASURING
          && edge2.getAllWaypoints().length > 2) {
        coordinateAfter = edge2.getAllWaypoints()[2];
      }
      double delta = getAngleOfCoords(coordinateBefore, crossingCoordinate,
          coordinateAfter);
      return delta;
    }
    return -360;
  }

  static double getAngleOfCoords(GeoCoordinate lastCoordinate,
      GeoCoordinate crossingCoordinate, GeoCoordinate firstCoordinate) {
    double delta;
    // calculate angles of the incoming street
    double deltaY = MercatorProjection.latitudeToMetersY(crossingCoordinate.getLatitude())
        - MercatorProjection.latitudeToMetersY(lastCoordinate.getLatitude());
    double deltaX = MercatorProjection
        .longitudeToMetersX(crossingCoordinate.getLongitude())
        - MercatorProjection.longitudeToMetersX(lastCoordinate.getLongitude());
    double alpha = java.lang.Math.toDegrees(java.lang.Math.atan(deltaX / deltaY));
    if (deltaY < 0) {
      alpha += 180; // this compensates for the atan result being between -90 and +90
    }
    // deg
    // calculate angles of the outgoing street
    deltaY = MercatorProjection.latitudeToMetersY(firstCoordinate.getLatitude())
        - MercatorProjection.latitudeToMetersY(crossingCoordinate.getLatitude());
    deltaX = MercatorProjection.longitudeToMetersX(firstCoordinate.getLongitude())
        - MercatorProjection.longitudeToMetersX(crossingCoordinate.getLongitude());
    double beta = java.lang.Math.toDegrees(java.lang.Math.atan(deltaX / deltaY));
    if (deltaY < 0) {
      beta += 180; // this compensates for the atan result being between -90 and +90
    }
    // deg
    // the angle difference is angle of the turn,
    delta = alpha - beta;
    // For some reason the angle is conterclockwise, so it's turned around
    delta = 360 - delta;
    // make sure there are no values above 360 or below 0
    delta = java.lang.Math.round((delta + 360) % 360);
    return delta;
  }
}
Java Source Code List
