+// 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.)
+
+static bool penaltyForNav(FGNavRecord* aNav, const SGGeod &aGeod)
+{
+ switch (aNav->type()) {
+ case FGPositioned::ILS:
+ case FGPositioned::LOC:
+ case FGPositioned::GS:
+// FIXME
+// case FGPositioned::DME: we can't get the heading for a DME transmitter, oops
+ break;
+ default:
+ return false;
+ }
+
+ double hdg_deg = 0.0;
+ if (aNav->type() == FGPositioned::GS) {
+ int tmp = (int)(aNav->get_multiuse() / 1000.0);
+ hdg_deg = aNav->get_multiuse() - (tmp * 1000);
+ } else {
+ hdg_deg = aNav->get_multiuse();
+ }
+
+ double az1, az2, s;
+ SGGeodesy::inverse(aGeod, aNav->geod(), az1, az2, s);
+ az1 = az1 - hdg_deg;
+ SG_NORMALIZE_RANGE(az1, -180.0, 180.0);
+ return fabs(az1) > 90.0;
+}