Add a "signed" distance to the GS transmitter. When you are in the approach

hemisphere the distance is positive, if you are in the departure hemisphere
the distance is negature.  (Possible use for graphing approach distance
vs. glide slope or cdi.)

diff --git a/src/Cockpit/navcom.cxx b/src/Cockpit/navcom.cxx
index a7a62cc09fd7fccd0407e1916a3e227ba61fba21..e621ddbf28cdb5dc725d56c4531d3e22f4819df1 100644 (file)
--- a/src/Cockpit/navcom.cxx
+++ b/src/Cockpit/navcom.cxx
@@ -323,12 +323,33 @@ FGNavCom::update(double dt)
        if ( nav_has_gs ) {
            station = Point3D( nav_gs_x, nav_gs_y, nav_gs_z );
            nav_gs_dist = aircraft.distance3D( station );
+            // wgs84 heading to glide slope
+            geo_inverse_wgs_84( elev,
+                                lat * SGD_RADIANS_TO_DEGREES,
+                                lon * SGD_RADIANS_TO_DEGREES, 
+                                nav_gslat, nav_gslon,
+                                &az1, &az2, &s );
+            double r = az1 - nav_radial;
+            while ( r >  180.0 ) { r -= 360.0;}
+            while ( r < -180.0 ) { r += 360.0;}
+            if ( r >= -90.0 && r <= 90.0 ) {
+                nav_gs_dist_signed = nav_gs_dist;
+            } else {
+                nav_gs_dist_signed = -nav_gs_dist;
+            }
+            /* cout << "Target Radial = " << nav_radial 
+                 << "  Bearing = " << az1
+                 << "  dist (signed) = " << nav_gs_dist_signed
+                 << endl; */
+            
        } else {
            nav_gs_dist = 0.0;
        }
        
-       // wgs84 heading
-       geo_inverse_wgs_84( elev, lat * SGD_RADIANS_TO_DEGREES, lon * SGD_RADIANS_TO_DEGREES, 
+       // wgs84 heading to localizer
+       geo_inverse_wgs_84( elev,
+                            lat * SGD_RADIANS_TO_DEGREES,
+                            lon * SGD_RADIANS_TO_DEGREES, 
                            nav_loclat, nav_loclon,
                            &az1, &az2, &s );
        // cout << "az1 = " << az1 << " magvar = " << nav_magvar << endl;

diff --git a/src/Cockpit/navcom.hxx b/src/Cockpit/navcom.hxx
index b01330ee4b37379563fe605486c0860a424bf930..33a01dcf510606df305a3c3d27ad69233c98fdb1 100644 (file)
--- a/src/Cockpit/navcom.hxx
+++ b/src/Cockpit/navcom.hxx
@@ -103,6 +103,7 @@ class FGNavCom : public FGSubsystem
     double nav_gs_y;
     double nav_gs_z;
     double nav_gs_dist;
+    double nav_gs_dist_signed;
     SGTimeStamp prev_time;
     SGTimeStamp curr_time;
     double nav_elev;
@@ -208,6 +209,7 @@ public:
     inline double get_nav_gslon() const { return nav_gslon; }
     inline double get_nav_gslat() const { return nav_gslat; }
     inline double get_nav_gs_dist() const { return nav_gs_dist; }
+    inline double get_nav_gs_dist_signed() const { return nav_gs_dist_signed; }
     inline double get_nav_elev() const { return nav_elev; }
     inline double get_nav_heading() const { return nav_heading; }
     inline double get_nav_radial() const { return nav_radial; }

diff --git a/src/Network/native_gui.cxx b/src/Network/native_gui.cxx
index 46ee30bdc6b89bfbc88f4ad1b814f4978529910d..30261b140a638e358ea200d286409cc7a4a52d42 100644 (file)
--- a/src/Network/native_gui.cxx
+++ b/src/Network/native_gui.cxx
@@ -154,8 +154,9 @@ void FGProps2NetGUI( FGNetGUI *net ) {
 
     if ( current_radiostack->get_navcom1()->get_nav_loc() ) {
         // is an ILS
-        net->dist_nm = current_radiostack->get_navcom1()->get_nav_gs_dist()
-            * SG_METER_TO_NM;
+        net->dist_nm
+            = current_radiostack->get_navcom1()->get_nav_gs_dist_signed()
+              * SG_METER_TO_NM;
     } else {
         // is a VOR
         net->dist_nm = current_radiostack->get_navcom1()->get_nav_loc_dist()