spheroid_direction()

double spheroid_direction	(	const GEOGRAPHIC_POINT *	a,
		const GEOGRAPHIC_POINT *	b,
		const SPHEROID *	spheroid
	)

Computes the forward azimuth of the geodesic joining two points on the spheroid, using the inverse geodesic problem (Karney 2013).

Parameters

r	- location of first point
s	- location of second point

Returns

azimuth of line joining r to s (but not reverse)

Definition at line 105 of file lwspheroid.c.

{
        struct geod_geodesic gd;
        geod_init(&gd, spheroid->a, spheroid->f);
        double lat1 = a->lat * 180.0 / M_PI;
        double lon1 = a->lon * 180.0 / M_PI;
        double lat2 = b->lat * 180.0 / M_PI;
        double lon2 = b->lon * 180.0 / M_PI;
        double azi1; /* return azimuth */
        geod_inverse(&gd, lat1, lon1, lat2, lon2, 0, &azi1, 0);
        return azi1 * M_PI / 180.0;
}

References SPHEROID::a, SPHEROID::f, GEOGRAPHIC_POINT::lat, and GEOGRAPHIC_POINT::lon.

Referenced by interpolate_point4d_spheroid(), and lwgeom_azumith_spheroid().

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