/**
* Returns the heading from one LatLng to another LatLng. Headings are
* expressed in degrees clockwise from North within the range [-180,180).
* @return The heading in degrees clockwise from north.
*/
public static function computeHeading($from, $to)
{
// http://williams.best.vwh.net/avform.htm#Crs
$fromLat = deg2rad($from['lat']);
$fromLng = deg2rad($from['lng']);
$toLat = deg2rad($to['lat']);
$toLng = deg2rad($to['lng']);
$dLng = $toLng - $fromLng;
$heading = atan2(sin($dLng) * cos($toLat), cos($fromLat) * sin($toLat) - sin($fromLat) * cos($toLat) * cos($dLng));
return MathUtil::wrap(rad2deg($heading), -180, 180);
}
private static function isLocationOnEdgeOrPath($point, $poly, $closed, $geodesic, $toleranceEarth)
{
$size = count($poly);
if ($size == 0) {
return false;
}
$tolerance = $toleranceEarth / MathUtil::EARTH_RADIUS;
$havTolerance = MathUtil::hav($tolerance);
$lat3 = deg2rad($point['lat']);
$lng3 = deg2rad($point['lng']);
$prev = !empty($closed) ? $poly[$size - 1] : 0;
$lat1 = deg2rad($prev['lat']);
$lng1 = deg2rad($prev['lng']);
if ($geodesic) {
foreach ($poly as $val) {
$lat2 = deg2rad($val['lat']);
$lng2 = deg2rad($val['lng']);
if (self::isOnSegmentGC($lat1, $lng1, $lat2, $lng2, $lat3, $lng3, $havTolerance)) {
return true;
}
$lat1 = $lat2;
$lng1 = $lng2;
}
} else {
// We project the points to mercator space, where the Rhumb segment is a straight line,
// and compute the geodesic distance between point3 and the closest point on the
// segment. This method is an approximation, because it uses "closest" in mercator
// space which is not "closest" on the sphere -- but the error is small because
// "tolerance" is small.
$minAcceptable = $lat3 - $tolerance;
$maxAcceptable = $lat3 + $tolerance;
$y1 = MathUtil::mercator($lat1);
$y3 = MathUtil::mercator($lat3);
$xTry = [];
foreach ($poly as $val) {
$lat2 = deg2rad($val['lat']);
$y2 = MathUtil::mercator($lat2);
$lng2 = deg2rad($val['lng']);
if (max($lat1, $lat2) >= $minAcceptable && min($lat1, $lat2) <= $maxAcceptable) {
// We offset longitudes by -lng1; the implicit x1 is 0.
$x2 = MathUtil::wrap($lng2 - $lng1, -M_PI, M_PI);
$x3Base = MathUtil::wrap(lng3 - lng1, -M_PI, M_PI);
$xTry[0] = $x3Base;
// Also explore wrapping of x3Base around the world in both directions.
$xTry[1] = $x3Base + 2 * M_PI;
$xTry[2] = $x3Base - 2 * M_PI;
foreach ($xTry as $x3) {
$dy = $y2 - $y1;
$len2 = $x2 * $x2 + $dy * $dy;
$t = $len2 <= 0 ? 0 : MathUtil::clamp(($x3 * $x2 + ($y3 - $y1) * $dy) / $len2, 0, 1);
$xClosest = $t * $x2;
$yClosest = $y1 + $t * $dy;
$latClosest = MathUtil::inverseMercator($yClosest);
$havDist = MathUtil::havDistance($lat3, $latClosest, $x3 - $xClosest);
if ($havDist < $havTolerance) {
return true;
}
}
}
$lat1 = $lat2;
$lng1 = $lng2;
$y1 = $y2;
}
}
return false;
}
