David Luff writes:

I've fixed a bug in FGRunways::search(aptid, tgt_hdg) which wasn't working properly for airports with multiple parallel runways. I've also firmed up and pulled out into it's own function the GetReverseRunwayNo code, and done some input checking.

As a result of fixing the above in runways.cxx, I've pulled out the
parallel implementation in the functions that set position by airport and
heading/runway number in fg_init.cxx and called the runways functions
instead.

src/Airports/runways.cxx

@@ -90,6 +90,47 @@ FGRunways::FGRunways( const string& file ) {
 }
 
 
+// Return reverse rwy number
+// eg 01 -> 19
+// 03L -> 21R
+static string GetReverseRunwayNo(string rwyno) {	
+    // cout << "Original rwyno = " << rwyNo << '\n';
+    
+    // standardize input number
+    string tmp = rwyno.substr(1, 1);
+    if (( tmp == "L" || tmp == "R" || tmp == "C" ) || (rwyno.size() == 1)) {
+	tmp = rwyno;
+	cout << "Standardising rwy number from " << tmp;
+	rwyno = "0" + tmp;
+	cout << " to " << rwyno << '\n';
+    }
+    
+    char buf[4];
+    int rn = atoi(rwyno.substr(0,2).c_str());
+    rn += 18;
+    while(rn > 36) {
+	rn -= 36;
+    }
+    sprintf(buf, "%02i", rn);
+    if(rwyno.size() == 3) {
+	if(rwyno.substr(2,1) == "L") {
+	    buf[2] = 'R';
+	    buf[3] = '\0';
+	} else if (rwyno.substr(2,1) == "R") {
+	    buf[2] = 'L';
+	    buf[3] = '\0';
+	} else if (rwyno.substr(2,1) == "C") {
+	    buf[2] = 'C';
+	    buf[3] = '\0';
+	} else {
+	    SG_LOG(SG_GENERAL, SG_ALERT, "Unknown runway code "
+	    << rwyno << " passed to GetReverseRunwayNo(...)");
+	}
+    }
+    return((string)buf);
+}
+
+
 // search for the specified apt id
 bool FGRunways::search( const string& aptid, FGRunway* r ) {
     c4_StringProp pID ("ID");
@@ -132,6 +173,7 @@ bool FGRunways::search( const string& aptid, FGRunway* r ) {
 // search for the specified apt id and runway no
 bool FGRunways::search( const string& aptid, const string& rwyno, FGRunway* r )
 {
+    string runwayno = rwyno;
     c4_StringProp pID ("ID");
     c4_StringProp pRwy ("Rwy");
     c4_FloatProp pLon ("Longitude");
@@ -150,13 +192,22 @@ bool FGRunways::search( const string& aptid, const string& rwyno, FGRunway* r )
 	return false;
     }
     
+    // standardize input number
+    string tmp = runwayno.substr(1, 1);
+    if (( tmp == "L" || tmp == "R" || tmp == "C" ) || (runwayno.size() == 1)) {
+	tmp = runwayno;
+	cout << "Standardising rwy number from " << tmp;
+	runwayno = "0" + tmp;
+	cout << " to " << runwayno << '\n';
+    }
+
     c4_RowRef row = vRunway->GetAt(index);
     string rowid = (const char *) pID(row);
     string rowrwyno = (const char *) pRwy(row);
     while ( rowid == aptid ) {
         next_index = index + 1;
 
-        if ( rowrwyno == rwyno ) {
+        if ( rowrwyno == runwayno ) {
             r->id =      (const char *) pID(row);
             r->rwy_no =  (const char *) pRwy(row);
             r->lon =     (double) pLon(row);
@@ -171,34 +222,11 @@ bool FGRunways::search( const string& aptid, const string& rwyno, FGRunway* r )
             return true;
         }
 	
-	// Check reverse rwy number
-	// eg 01 -> 19
-	// 03L -> 21R
-	// cout << "Original rowrwyno = " << rowrwyno << '\n';
-	char buf[4];
-	int rn = atoi(rowrwyno.substr(0,2).c_str());
-	rn += 18;
-	while(rn > 36) {
-	    rn -= 36;
-	}
-	sprintf(buf, "%02i", rn);
-	if(rowrwyno.size() == 3) {
-	    if(rowrwyno.substr(2,1) == "L") {
-		buf[2] = 'R';
-		buf[3] = '\0';
-	    } else if (rowrwyno.substr(2,1) == "R") {
-		buf[2] = 'L';
-		buf[3] = '\0';
-	    } else {
-		SG_LOG(SG_GENERAL, SG_ALERT, "Unknown runway code "
-                       << rowrwyno << " found in FGRunways.search(...)");
-	    }
-	}
-	rowrwyno = buf;
-	// cout << "New rowrwyno = " << rowrwyno << '\n';
 	// Search again with the other-end runway number
-	// Remember we have to munge the heading result if this one matches
+	// Remember we have to munge the heading and rwy_no results if this one matches
-	if ( rowrwyno == rwyno ) {
+	rowrwyno = GetReverseRunwayNo(rowrwyno);
+	// cout << "New rowrwyno = " << rowrwyno << '\n';
+	if ( rowrwyno == runwayno ) {
 	    r->id =      (const char *) pID(row);
 	    r->rwy_no =  rowrwyno;
 	    r->lon =     (double) pLon(row);
@@ -285,10 +313,11 @@ bool FGRunways::search( const string& aptid, const int tgt_hdg,
 // Return the runway number of the runway closest to a given heading
 string FGRunways::search( const string& aptid, const int tgt_hdg ) {
     FGRunway r;
+    FGRunway tmp_r;	
     string rn;
     double found_dir = 0.0;  
  
-    if ( !search( aptid, &r ) ) {
+    if ( !search( aptid, &tmp_r ) ) {
 	SG_LOG( SG_GENERAL, SG_ALERT,
                 "Failed to find " << aptid << " in database." );
 	return "NN";
@@ -297,7 +326,9 @@ string FGRunways::search( const string& aptid, const int tgt_hdg ) {
     double diff;
     double min_diff = 360.0;
     
-    while ( r.id == aptid ) {
+    while ( tmp_r.id == aptid ) {
+	r = tmp_r;
+	
 	// forward direction
 	diff = tgt_hdg - r.heading;
 	while ( diff < -180.0 ) { diff += 360.0; }
@@ -327,22 +358,16 @@ string FGRunways::search( const string& aptid, const int tgt_hdg ) {
 	    found_dir = 180.0;
 	}
 	
-	next( &r );
+	next( &tmp_r );
     }
     
     // SG_LOG( SG_GENERAL, SG_INFO, "closest runway = " << r.rwy_no
     //	       << " + " << found_dir );
-    // rn = r.rwy_no;
+    rn = r.rwy_no;
     // cout << "In search, rn = " << rn << endl;
     if ( found_dir == 180 ) {
-	int irn = atoi(rn.c_str());
+	rn = GetReverseRunwayNo(rn);
-	irn += 18;
+	//cout << "New rn = " << rn << '\n';
-	if ( irn > 36 ) {
-	    irn -= 36;
-	}
-	char buf[4];            // 2 chars + string terminator + 1 for safety
-	sprintf(buf, "%i", irn);
-	rn = buf;
     }	
     
     return rn;

src/Main/fg_init.cxx

@@ -655,8 +655,6 @@ static bool fgSetTowerPosFromAirportID( const string& id, double hdg ) {
 // Set current_options lon/lat given an airport id and heading (degrees)
 static bool fgSetPosFromAirportIDandHdg( const string& id, double tgt_hdg ) {
     FGRunway r;
-    FGRunway found_r;
-    double found_dir = 0.0;
 
     if ( id.length() ) {
         // set initial position from runway and heading
@@ -667,72 +665,30 @@ static bool fgSetPosFromAirportIDandHdg( const string& id, double tgt_hdg ) {
         FGRunways runways( path.c_str() );
 
         SG_LOG( SG_GENERAL, SG_INFO,
-                "Attempting to set starting position from runway code "
+                "Attempting to set starting position from airport code "
                 << id << " heading " << tgt_hdg );
 		
-        if ( ! runways.search( id, &r ) ) {
+        if ( ! runways.search( id, (int)tgt_hdg, &r ) ) {
             SG_LOG( SG_GENERAL, SG_ALERT,
-                    "Failed to find " << id << " in database." );
+                    "Failed to find a good runway for " << id << '\n' );
             return false;
         }	
-
-        double diff;
-        double min_diff = 360.0;
-
-        while ( r.id == id ) {
-            // forward direction
-            diff = tgt_hdg - r.heading;
-            while ( diff < -180.0 ) { diff += 360.0; }
-            while ( diff >  180.0 ) { diff -= 360.0; }
-            diff = fabs(diff);
-            SG_LOG( SG_GENERAL, SG_INFO,
-                    "Runway " << r.rwy_no << " heading = " << r.heading <<
-                    " diff = " << diff );
-            if ( diff < min_diff ) {
-                min_diff = diff;
-                found_r = r;
-                found_dir = 0;
-            }
-
-            // reverse direction
-            diff = tgt_hdg - r.heading - 180.0;
-            while ( diff < -180.0 ) { diff += 360.0; }
-            while ( diff >  180.0 ) { diff -= 360.0; }
-            diff = fabs(diff);
-            SG_LOG( SG_GENERAL, SG_INFO,
-                    "Runway -" << r.rwy_no << " heading = " <<
-                    r.heading + 180.0 <<
-                    " diff = " << diff );
-            if ( diff < min_diff ) {
-                min_diff = diff;
-                found_r = r;
-                found_dir = 180.0;
-            }
-
-            runways.next( &r );
-        }
-
-        SG_LOG( SG_GENERAL, SG_INFO, "closest runway = " << found_r.rwy_no
-                << " + " << found_dir );
-
     } else {
         return false;
     }
 
-    double heading = found_r.heading + found_dir;
-    while ( heading >= 360.0 ) { heading -= 360.0; }
-
     double lat2, lon2, az2;
-    double azimuth = found_r.heading + found_dir + 180.0;
+    double heading = r.heading;
+    double azimuth = heading + 180.0;
     while ( azimuth >= 360.0 ) { azimuth -= 360.0; }
 
     SG_LOG( SG_GENERAL, SG_INFO,
-            "runway =  " << found_r.lon << ", " << found_r.lat
+            "runway =  " << r.lon << ", " << r.lat
-            << " length = " << found_r.length * SG_FEET_TO_METER * 0.5 
+            << " length = " << r.length * SG_FEET_TO_METER 
             << " heading = " << azimuth );
 	    
-    geo_direct_wgs_84 ( 0, found_r.lat, found_r.lon, 
+    geo_direct_wgs_84 ( 0, r.lat, r.lon, azimuth, 
-                        azimuth, found_r.length * SG_FEET_TO_METER * 0.5 - 5.0,
+                        r.length * SG_FEET_TO_METER * 0.5 - 5.0,
                         &lat2, &lon2, &az2 );
 
     if ( fabs( fgGetDouble("/sim/presets/offset-distance") ) > SG_EPSILON ) {
@@ -769,25 +725,12 @@ static bool fgSetPosFromAirportIDandHdg( const string& id, double tgt_hdg ) {
 }
 
 
-// Set current_options lon/lat given an airport id and heading (degrees)
+// Set current_options lon/lat given an airport id and runway number
 static bool fgSetPosFromAirportIDandRwy( const string& id, const string& rwy ) {
     FGRunway r;
-    FGRunway found_r;
-    double heading = 0.0;
-    string runway;
-    bool match = false;
-
-    // standardize input number
-    string tmp = rwy.substr(1, 1);
-    if ( tmp == "L" || tmp == "R" || tmp == "C" ) {
-        runway = "0";
-        runway += rwy;
-    } else {
-        runway = rwy;
-    }
 
     if ( id.length() ) {
-        // set initial position from runway and heading
+        // set initial position from airport and runway number
 
         SGPath path( globals->get_fg_root() );
         path.append( "Airports" );
@@ -798,84 +741,29 @@ static bool fgSetPosFromAirportIDandRwy( const string& id, const string& rwy ) {
                 "Attempting to set starting position for "
                 << id << ":" << runway );
 
-        if ( ! runways.search( id, &r ) ) {
+        if ( ! runways.search( id, rwy, &r ) ) {
             SG_LOG( SG_GENERAL, SG_ALERT,
-                    "Failed to find " << id << " in database." );
+                    "Failed to find runway " << rwy << 
+                    " at airport " << id );
             return false;
         }
-
-        while ( r.id == id ) {
-            // forward direction
-            if ( r.rwy_no == runway ) {
-                found_r = r;
-                heading = r.heading;
-                match = true;
-                SG_LOG( SG_GENERAL, SG_INFO,
-                        "Runway " << r.rwy_no << " heading = " << heading );
-            }
-
-            // calculate reciprocal runway number
-            string snum = r.rwy_no;
-            int len = snum.length();
-            string letter = "";
-            string rev_letter = "";
-            int i;
-            for ( i = 0; i < len; ++i ) {
-                string tmp = snum.substr(i, 1);
-                if ( tmp == "L" ) {
-                    letter = "L";
-                    rev_letter = "R";
-                } else if ( tmp == "R" ) {
-                    letter = "R";
-                    rev_letter = "L";
-                } else if ( tmp == "C" ) {
-                    letter == "C";
-                    rev_letter = "C";
-                }
-            }
-            for ( i = 0; i < len; ++i ) {
-                string tmp = snum.substr(i, 1);
-                if ( tmp == "L" || tmp == "R" || tmp == "C" || tmp == " " ) {
-                    snum = snum.substr(0, i);
-                }
-            }
-            SG_LOG(SG_GENERAL, SG_DEBUG, "Runway num = '" << snum << "'");
-            int num = atoi( snum.c_str() ) + 18;
-            while ( num > 36 ) { num -= 36; }
-            while ( num <= 0 ) { num += 36; }
-
-            char recip_no[10];
-            snprintf( recip_no, 10, "%02d%s", num, rev_letter.c_str() );
-
-            // reverse direction
-            if ( (string)recip_no == runway ) {
-                found_r = r;
-                heading = r.heading + 180;
-                while ( heading > 360.0 ) { heading -= 360; }
-                match = true;
-                SG_LOG( SG_GENERAL, SG_INFO,
-                        "Runway " << r.rwy_no << " heading = " << heading );
-            }
-
-            runways.next( &r );
-        }
     } else {
         return false;
     }
 
-    if ( match ) {
     double lat2, lon2, az2;
+    double heading = r.heading;
     double azimuth = heading + 180.0;
     while ( azimuth >= 360.0 ) { azimuth -= 360.0; }
     
     SG_LOG( SG_GENERAL, SG_INFO,
-                "runway =  " << found_r.lon << ", " << found_r.lat
+    "runway =  " << r.lon << ", " << r.lat
-                << " length = " << found_r.length * SG_FEET_TO_METER * 0.5 
+    << " length = " << r.length * SG_FEET_TO_METER 
     << " heading = " << azimuth );
     
-        geo_direct_wgs_84 ( 0, found_r.lat, found_r.lon, 
+    geo_direct_wgs_84 ( 0, r.lat, r.lon, 
     azimuth,
-                            found_r.length * SG_FEET_TO_METER * 0.5 - 5.0,
+    r.length * SG_FEET_TO_METER * 0.5 - 5.0,
     &lat2, &lon2, &az2 );
     
     if ( fabs( fgGetDouble("/sim/presets/offset-distance") ) > SG_EPSILON )
@@ -911,9 +799,6 @@ static bool fgSetPosFromAirportIDandRwy( const string& id, const string& rwy ) {
     << heading );
     
     return true;
-    } else {
-        return false;
-    }
 }