Merge branch 'jmt/reciprocal'

src/Airports/apt_loader.cxx

@@ -286,6 +286,9 @@ private:
                 displ_thresh2, stopway2, surface_code, true);
 
       runways.push_back(reciprocal);
+      
+      rwy->setReciprocalRunway(reciprocal);
+      reciprocal->setReciprocalRunway(rwy);
     }
   }
 
@@ -335,6 +338,9 @@ private:
               pos, heading_2, length, width, 
               displ_thresh2, stopway2, surface_code, true);
     runways.push_back(reciprocal);
+    
+    rwy->setReciprocalRunway(reciprocal);
+    reciprocal->setReciprocalRunway(rwy);
   }
 
   void parseWaterRunwayLine850(const vector<string>& token)
@@ -373,6 +379,9 @@ private:
               pos, heading_2, length, width, 
               0.0, 0.0, 13, true);
     runways.push_back(reciprocal);
+    
+    rwy->setReciprocalRunway(reciprocal);
+    reciprocal->setReciprocalRunway(rwy);
   }
 
   void parseHelipadLine850(const vector<string>& token)

src/Airports/runways.cxx

@@ -71,7 +71,8 @@ FGRunway::FGRunway(FGAirport* aAirport, const string& aIdent,
                         bool reciprocal) :
   FGRunwayBase(RUNWAY, cleanRunwayNo(aIdent), aGeod, heading, length, width, surface_code, true),
   _airport(aAirport),
-  _reciprocal(reciprocal),
+  _isReciprocal(reciprocal),
+  _reciprocal(NULL),
   _displ_thresh(displ_thresh),
   _stopway(stopway),
   _ils(NULL)
@@ -158,3 +159,12 @@ void FGRunway::processThreshold(SGPropertyNode* aThreshold)
   SGGeodesy::direct(newThreshold, _heading, offsetFt * SG_FEET_TO_METER, newCenter, dummy);
   mPosition = newCenter;
 } 
+
+void FGRunway::setReciprocalRunway(FGRunway* other)
+{
+  assert(_reciprocal==NULL);
+  assert((other->_reciprocal == NULL) || (other->_reciprocal == this));
+  
+  _reciprocal = other;
+}
+

src/Airports/runways.hxx

@@ -36,7 +36,8 @@ class SGPropertyNode;
 class FGRunway : public FGRunwayBase
 {
   FGAirport* _airport;
-  bool _reciprocal;
+  bool _isReciprocal;
+  FGRunway* _reciprocal;
   double _displ_thresh;
   double _stopway;
   FGNavRecord* _ils;
@@ -68,7 +69,7 @@ public:
    * over runways to avoid counting runways twice, if desired.
    */
   bool isReciprocal() const
-  { return _reciprocal; }
+  { return _isReciprocal; }
 
   /**
    * Get the runway begining point - this is syntatic sugar, equivalent to
@@ -106,6 +107,10 @@ public:
   FGNavRecord* ILS() const { return _ils; }
   void setILS(FGNavRecord* nav) { _ils = nav; }
   
+  FGRunway* reciprocalRunway() const
+  { return _reciprocal; }
+  void setReciprocalRunway(FGRunway* other);
+  
   /**
    * Helper to process property data loaded from an ICAO.threshold.xml file
    */

src/Navaids/navlist.cxx

@@ -31,6 +31,8 @@
 
 #include "navlist.hxx"
 
+#include <Airports/runways.hxx>
+
 using std::string;
 
 // FGNavList ------------------------------------------------------------------
@@ -108,49 +110,38 @@ FGNavRecord *FGNavList::findByIdentAndFreq(const string& ident, const double fre
   return NULL;
 }
 
-// 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)
+// discount navids if they conflict with another on the same frequency
+// this only applies to navids associated with opposite ends of a runway,
+// with matching frequencies.
+static bool navidUsable(FGNavRecord* aNav, const SGGeod &aircraft)
 {
-  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;
+  FGRunway* r(aNav->runway());
+  if (!r || !r->reciprocalRunway()) {
+    return true;
   }
   
-  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();
+// check if the runway frequency is paired
+  FGNavRecord* locA = r->ILS();
+  FGNavRecord* locB = r->reciprocalRunway()->ILS();
+  
+  if (!locA || !locB || (locA->get_freq() != locB->get_freq())) {
+    return true; // not paired, ok
   }
   
-  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;
+// okay, both ends have an ILS, and they're paired. We need to select based on
+// aircraft position. What we're going to use is *runway* (not navid) position,
+// ie whichever runway end we are closer too. This makes back-course / missed
+// approach behaviour incorrect, but that's the price we accept.
+  double crs = SGGeodesy::courseDeg(aircraft, r->geod());
+  double hdgDiff = crs - r->headingDeg();
+  SG_NORMALIZE_RANGE(hdgDiff, -180.0, 180.0);  
+  return (fabs(hdgDiff) < 90.0);
 }
 
-// Given a point and a list of stations, return the closest one to the
-// specified point.
-FGNavRecord *FGNavList::findNavFromList( const SGGeod &aircraft,
-                                         const nav_list_type &stations )
+// Given a point and a list of stations, return the closest one to
+// the specified point.
+FGNavRecord* FGNavList::findNavFromList( const SGGeod &aircraft,
+                                  const nav_list_type &stations )
 {
     FGNavRecord *nav = NULL;
     double d2;                  // in meters squared
@@ -163,18 +154,13 @@ FGNavRecord *FGNavList::findNavFromList( const SGGeod &aircraft,
     // 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->cart(), aircraftCart);
-        if ( d2 < min_dist && penaltyForNav(station, aircraft))
-        {
-          double dist = sqrt(d2);
-          d2 = (dist + 5000) * (dist + 5000);
+        if ( d2 > min_dist || !navidUsable(station, aircraft)) {
+          continue;
         }
         
-        if ( d2 < min_dist ) {
-            min_dist = d2;
-            nav = station;
-        }
+        min_dist = d2;
+        nav = station;
     }
 
     return nav;

src/Navaids/navrecord.cxx

@@ -101,7 +101,7 @@ void FGNavRecord::initAirportRelation()
     mPosition.setElevationFt(mRunway->elevation());
   }
   
-  if (type() == ILS) {
+  if (type() == ILS || type() == LOC) {
     mRunway->setILS(this);
   }