X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FTime%2Ffg_time.cxx;h=297c28f53e8cc7a207ae4316c79cdd3bc3d8bf10;hb=7a16ec4fb4e1663902f5022812291f01d7e37ee3;hp=9e93015cf898d5be4636432305d7906e0b577d45;hpb=10ceaa4ba0701cc7812d004e3f0e88f2e1ce9009;p=flightgear.git

diff --git a/src/Time/fg_time.cxx b/src/Time/fg_time.cxx
index 9e93015cf..297c28f53 100644
--- a/src/Time/fg_time.cxx
+++ b/src/Time/fg_time.cxx
@@ -51,6 +51,7 @@
 
 #include <simgear/constants.h>
 #include <simgear/debug/logstream.hxx>
+#include <simgear/magvar/magvar.hxx>
 #include <simgear/misc/fgpath.hxx>
 
 #include <FDM/flight.hxx>
@@ -336,7 +337,7 @@ double FGTime::sidereal_course(double lng)
 
 
 // Update time variables such as gmt, julian date, and sidereal time
-void FGTime::update( double lon ) {
+void FGTime::update( double lon, double lat, double alt_m ) {
     double gst_precise, gst_course;
 
     FG_LOG( FG_EVENT, FG_DEBUG, "Updating time" );
@@ -393,6 +394,13 @@ void FGTime::update( double lon ) {
 	gst = sidereal_course( 0.00 ) + gst_diff;
 	lst = sidereal_course( -(lon * RAD_TO_DEG)) + gst_diff;
     }
+
+    // Calculate local magnetic variation
+    double field[6];
+    // cout << "alt_m = " << alt_m << endl;
+    magvar = SGMagVar( lat, lon, alt_m / 1000.0, jd, field );
+    magdip = atan(field[5]/pow(field[3]*field[3]+field[4]*field[4],0.5));
+
     FG_LOG( FG_EVENT, FG_DEBUG,
 	    "  Current lon=0.00 Sidereal Time = " << gst );
     FG_LOG( FG_EVENT, FG_DEBUG,