From: curt <curt>
Date: Wed, 22 Jan 2003 01:24:32 +0000 (+0000)
Subject: Add a "signed" distance to the GS transmitter.  When you are in the approach
X-Git-Url: https://git.mxchange.org/?a=commitdiff_plain;h=29a35258698bb583437d86757211f93896515404;p=flightgear.git

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 a7a62cc09..e621ddbf2 100644
--- 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 b01330ee4..33a01dcf5 100644
--- 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 46ee30bdc..30261b140 100644
--- 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()