Merge pull request #206 from scdwyer/fg2.6

Fixes simulations for visualization in FlightGear 2.6
If you still want to use FlightGear 2.4, define FG_2_4 to 1.

sw/simulator/flight_gear.h

@@ -208,21 +208,35 @@ struct FGNetMiniFDM {
     int32_t warp;                 // offset in seconds to unix time
 };
 
+#if FG_2_4
 #define FG_NET_GUI_VERSION 7
+#else
+#define FG_NET_GUI_VERSION 8
+#endif /*FG_2_4*/
+
 #define FG_NET_GUI_MAX_TANKS 4
 
-// FIXME: Flightgear on OSX is still 32 bit get rid
-// off these pragmas when it goes to 64 bit.
+// Prior to FG_NET_GUI_VERSION 8, OS X needed #pragma pack(4) to
+// properly display FG visualization data. In version 8 they added
+// a padding1 element to ensure proper data alignment, so this is
+// no longer required. The rest of this struct is based on FG source
+// in src/Network/net_gui.hxx
+
+#if FG_2_4
 #ifdef __x86_64__
 #pragma pack(push)
 #ifdef __APPLE__
 #pragma pack(4)
 #else
 #pragma pack(8)
-#endif
-#endif
+#endif /*__APPLE__*/
+#endif /*__x86_64__*/
+#endif /*FG_2_4*/
 struct FGNetGUI {
   uint32_t version;           // increment when data values change
+#if FG_2_4
+  uint32_t padding1;
+#endif /*FG_2_4*/
 
   // Positions
   double longitude;           // geodetic (radians)
@@ -255,10 +269,12 @@ struct FGNetGUI {
   float course_deviation_deg; // degrees off target course
   float gs_deviation_deg;     // degrees off target glide slope
 };
+#if FG_2_4
 #ifdef __x86_64__
 #pragma pack(push)
 #pragma pack(pop)
-#endif
+#endif /*__x86_64__*/
+#endif /*FG_2_4*/
 
 
 extern void net_fdm_dump (struct FGNetFDM* fdm);