-// Given a point and a list of stations, return the closest one to the
-// specified point.
-FGNavRecord *FGNavList::findNavFromList( const SGVec3d &aircraft,
- const nav_list_type &stations )
-{
- FGNavRecord *nav = NULL;
- double d2; // in meters squared
- double min_dist
- = FG_NAV_MAX_RANGE*SG_NM_TO_METER*FG_NAV_MAX_RANGE*SG_NM_TO_METER;
-
- nav_list_const_iterator it;
- nav_list_const_iterator end = stations.end();
- // find the closest station within a sensible range (FG_NAV_MAX_RANGE)
- for ( it = stations.begin(); it != end; ++it ) {
- FGNavRecord *station = *it;
- // cout << "testing " << current->get_ident() << endl;
- d2 = distSqr(station->get_cart(), aircraft);
-
- // cout << " dist = " << sqrt(d)
- // << " range = " << current->get_range() * SG_NM_TO_METER
- // << endl;
-
- // LOC, ILS, GS, and DME antenna's could potentially be
- // installed at the opposite end of the runway. So it's not
- // enough to simply find the closest antenna with the right
- // frequency. We need the closest antenna with the right
- // frequency that is most oriented towards us. (We penalize
- // stations that are facing away from us by adding 5000 meters
- // which is further than matching stations would ever be
- // placed from each other. (Do the expensive check only for
- // directional atennas and only when there is a chance it is
- // the closest station.)
- int type = station->get_type();
- if ( d2 < min_dist &&
- (type == 4 || type == 5 || type == 6 || type == 12 || type == 13) )
- {
- double hdg_deg = 0.0;
- if ( type == 4 || type == 5 ){
- hdg_deg = station->get_multiuse();
-
- } else if ( type == 6 ) {
- int tmp = (int)(station->get_multiuse() / 1000.0);
- hdg_deg = station->get_multiuse() - (tmp * 1000);
-
- } else if ( type == 12 || type == 13 ) {
- // oops, Robin's data format doesn't give us the
- // needed information to compute a heading for a DME
- // transmitter. FIXME Robin!
- }
-
- double az1 = 0.0, az2 = 0.0, s = 0.0;
- SGGeod geod = SGGeod::fromCart(aircraft);
- geo_inverse_wgs_84( geod, station->get_pos(), &az1, &az2, &s);
- az1 = az1 - station->get_multiuse();
- if ( az1 > 180.0) az1 -= 360.0;
- if ( az1 < -180.0) az1 += 360.0;
- // penalize opposite facing stations by adding 5000 meters
- // (squared) which is further than matching stations would
- // ever be placed from each other.
- if ( fabs(az1) > 90.0 ) {
- double dist = sqrt(d2);
- d2 = (dist + 5000) * (dist + 5000);
- }
- }
-
- if ( d2 < min_dist ) {
- min_dist = d2;
- nav = station;
- }