}
-// query the database for the specified frequency, lon and lat are in
-// degrees, elev is in meters
-bool FGNavList::query( double lon, double lat, double elev, double freq,
- FGNav *n )
+// Query the database for the specified frequency. It is assumed that
+// there will be multiple stations with matching frequencies so a
+// position must be specified. Lon and lat are in degrees, elev is in
+// meters.
+FGNav *FGNavList::findByFreq( double freq, double lon, double lat, double elev )
{
nav_list_type stations = navaids[(int)(freq*100.0 + 0.5)];
+ Point3D aircraft = sgGeodToCart( Point3D(lon, lat, elev) );
+
+ return findNavFromList( aircraft, stations );
+}
- nav_list_iterator current = stations.begin();
- nav_list_iterator last = stations.end();
- Point3D aircraft = sgGeodToCart( Point3D(lon, lat, elev) );
- return findNavFromList(aircraft, current, last, n);
+FGNav *FGNavList::findByIdent( const char* ident,
+ const double lon, const double lat )
+{
+ nav_list_type stations = ident_navaids[ident];
+ Point3D aircraft = sgGeodToCart( Point3D(lon, lat, 0.0) );
+
+ return findNavFromList( aircraft, stations );
}
-bool FGNavList::findByIdent(const char* ident, double lon, double lat,
- FGNav *nav)
+// Given an Ident and optional freqency, return the first matching
+// station.
+FGNav *FGNavList::findByIdentAndFreq( const char* ident, const double freq )
{
nav_list_type stations = ident_navaids[ident];
- nav_list_iterator current = stations.begin();
- nav_list_iterator last = stations.end();
-
- Point3D aircraft = sgGeodToCart( Point3D(lon, lat, 0.0) );
- return findNavFromList(aircraft, current, last, nav);
+ if ( freq > 0.0 ) {
+ // sometimes there can be duplicated idents. If a freq is
+ // specified, use it to refine the search.
+ int f = (int)(freq*100.0 + 0.5);
+ for ( unsigned int i = 0; i < stations.size(); ++i ) {
+ if ( f == stations[i]->get_freq() ) {
+ return stations[i];
+ }
+ }
+ } else {
+ return stations[0];
+ }
+
+ return NULL;
}
-bool FGNavList::findNavFromList(const Point3D &aircraft,
- nav_list_iterator current,
- nav_list_iterator end, FGNav *n)
+// Given a point and a list of stations, return the closest one to the
+// specified point.
+FGNav *FGNavList::findNavFromList( const Point3D &aircraft,
+ const nav_list_type &stations )
{
- // double az1, az2, s;
-
+ FGNav *nav = NULL;
Point3D station;
- double d;
- for ( ; current != end ; ++current ) {
+ double d2;
+ double min_dist = 999999999.0;
+
+ // prime the pump with info from stations[0]
+ if ( stations.size() > 0 ) {
+ nav = stations[0];
+ station = Point3D( nav->get_x(), nav->get_y(), nav->get_z());
+ min_dist = aircraft.distance3Dsquared( station );
+ }
+
+ // check if any of the remaining stations are closer
+ for ( unsigned int i = 1; i < stations.size(); ++i ) {
// cout << "testing " << current->get_ident() << endl;
- station = Point3D((*current)->get_x(), (*current)->get_y(),
- (*current)->get_z());
+ station = Point3D( stations[i]->get_x(),
+ stations[i]->get_y(),
+ stations[i]->get_z() );
- d = aircraft.distance3Dsquared( station );
+ d2 = aircraft.distance3Dsquared( station );
// cout << " dist = " << sqrt(d)
// << " range = " << current->get_range() * SG_NM_TO_METER
// << endl;
- // match up to 2 * range^2 the published range so we can model
- // reduced signal strength
- double twiceRange = 2 * (*current)->get_range() * SG_NM_TO_METER;
- if ( d < (twiceRange * twiceRange)) {
- // cout << "matched = " << current->get_ident() << endl;
- *n = (**current);
- return true;
- }
+ if ( d2 < min_dist ) {
+ min_dist = d2;
+ nav = stations[i];
+ }
}
- return false;
+ return nav;
}