2

我有用户当前位置，即 CLLocation 坐标（位置经纬度）并且用户在赛道上，借助用户当前位置指向一个方向我现在创建了一个区域我想要更多赛道坐标（比如 2m、4m、6m垂直方向远离赛道），赛道长 10 m。请检查图像，红点在轨道上。 请检查此图像

4

1 回答 1

0 
/**
 * Returns the destination point from initial point having travelled the given distance on the
 * given initial bearing (bearing normally varies around path followed).
 *
 * @param   {double} distance - Distance travelled, in same units as earth radius (default: metres).
 * @param   {double} bearing - Initial bearing in degrees from north.
 *
 * @returns {CLLocationCoordinate} Destination point.
 */

#define kEarthRadius 6378137

- (CLLocationCoordinate2D)destinationPointWithStartingPoint:(MKMapPoint)initialPoint distance:(double)distance andBearing:(double)bearing {
  CLLocationCoordinate2D location = MKCoordinateForMapPoint(initialPoint);

  double delta = distance / kEarthRadius;
  double omega = [self degreesToRadians:bearing];

  double phi1 = [self degreesToRadians:location.latitude];
  double lambda1 = [self degreesToRadians:location.longitude];

  double phi2 = asin(sin(phi1)*cos(delta) + cos(phi1) * sin(delta) * cos(omega));
  double x = cos(delta) - sin(phi1) * sin(phi2);
  double y = sin(omega) * sin(delta) * cos(phi1);
  double lambda2 = lambda1 + atan2(y, x);

  return CLLocationCoordinate2DMake([self radiansToDegrees:phi2], ([self radiansToDegrees:lambda2]+540)%360-180);
}

- (CLLocationCoordinate2D)rhumbDestinationPointForInitialPoint:(MKMapPoint)initialPoint distance:(double)distance andBearing:(double)bearing {
  CLLocationCoordinate2D location = MKCoordinateForMapPoint(initialPoint);

  double delta = distance / kEarthRadius;
  double omega = [self degreesToRadians:bearing];

  double phi1 = [self degreesToRadians:location.latitude];
  double lambda1 = [self degreesToRadians:location.longitude];

  double delta_phi = delta * cos(omega);
  double phi2 = phi1 + delta_phi;

  // check for some daft bugger going past the pole, normalise latitude if so
  if (fabs(phi2) > M_PI / 2) {
    phi2 = phi2 > 0 ? M_PI-phi2 : -M_PI-phi2;
  }

  double delta_gamma = log(tan(phi2/2+M_PI/4)/tan(phi1/2+M_PI/4));
  double q = fabs(delta_gamma) > 10e-12 ? delta_phi / delta_gamma : cos(phi1);

  double delta_lambda = delta*sin(omega)/q;
  double lambda2 = lambda1 + delta_lambda;

  return CLLocationCoordinate2DMake([self radiansToDegrees:phi2], ([self radiansToDegrees:lambda2]+540)%360-180);
}

- (double)degreesToRadians:(double)degrees {
  return degrees * M_PI / 180.0;
}

- (double)radiansToDegrees:(double)radians {
  return radians * 180.0 / M_PI;
}

改编自：http
://www.movable-type.co.uk/scripts/latlong.html 更多关于轴承的信息：https://en.wikipedia.org/wiki/Bearing_(navigation )
和大黄线：https:// /en.wikipedia.org/wiki/Rhumb_line

于 2016-04-04T13:59:26.607 回答