Mark's dynamic sun color changes.

src/Environment/environment.cxx

@@ -128,10 +128,13 @@ FGEnvironment::FGEnvironment()
     wind_speed_kt(0),
     wind_from_north_fps(0),
     wind_from_east_fps(0),
-    wind_from_down_fps(0)
+    wind_from_down_fps(0),
+    altitude_half_to_sun_m(1000),
+    altitude_tropo_top_m(10000)
 {
   _setup_tables();
   _recalc_density();
+  _recalc_relative_humidity();
 }
 
 FGEnvironment::FGEnvironment (const FGEnvironment &env)
@@ -271,6 +274,30 @@ FGEnvironment::get_density_slugft3 () const
   return density_slugft3;
 }
 
+double
+FGEnvironment::get_relative_humidity () const
+{
+  return relative_humidity;
+}
+
+double
+FGEnvironment::get_density_tropo_avg_kgm3 () const
+{
+  return density_tropo_avg_kgm3;
+}
+
+double
+FGEnvironment::get_altitude_half_to_sun_m () const
+{
+  return altitude_half_to_sun_m;
+}
+
+double
+FGEnvironment::get_altitude_tropo_top_m () const
+{
+  return altitude_tropo_top_m;
+}
+
 double
 FGEnvironment::get_wind_from_heading_deg () const
 {
@@ -344,6 +371,7 @@ FGEnvironment::set_temperature_degc (double t)
   temperature_degc = t;
   _recalc_sl_temperature();
   _recalc_density();
+  _recalc_relative_humidity();
 }
 
 void
@@ -362,6 +390,7 @@ FGEnvironment::set_dewpoint_degc (double t)
   dewpoint_degc = t;
   _recalc_sl_dewpoint();
   _recalc_density();
+  _recalc_relative_humidity();
 }
 
 void
@@ -435,8 +464,24 @@ FGEnvironment::set_elevation_ft (double e)
   _recalc_alt_dewpoint();
   _recalc_alt_pressure();
   _recalc_density();
+  _recalc_relative_humidity();
 }
 
+void
+FGEnvironment::set_altitude_half_to_sun_m (double alt)
+{
+ altitude_half_to_sun_m = alt;
+ _recalc_density_tropo_avg_kgm3();
+}
+
+void
+FGEnvironment::set_altitude_tropo_top_m (double alt)
+{
+ altitude_tropo_top_m = alt;
+ _recalc_density_tropo_avg_kgm3();
+}
+
+
 void
 FGEnvironment::_recalc_hdgspd ()
 {
@@ -558,10 +603,35 @@ FGEnvironment::_recalc_density ()
   double virtual_temperature_degr = virtual_temperature_degk * 1.8;
 
   density_slugft3 = pressure_psf / (virtual_temperature_degr * 1718);
+  _recalc_density_tropo_avg_kgm3();
+}
+
+// This is used to calculate the average density on the path 
+// of sunlight to the observer for calculating sun-color
+void
+FGEnvironment::_recalc_density_tropo_avg_kgm3 ()
+{
+  double pressure_mb = pressure_inhg * 33.86;
+  double vaporpressure = 6.11 * pow ( 10, ((7.5 * dewpoint_degc) /( 237.7 + dewpoint_degc)));
+
+  double virtual_temp = (temperature_degc + 273.15) / (1 - 0.379 * (vaporpressure/pressure_mb));
+
+  double density_half = (100* pressure_mb * exp (-altitude_half_to_sun_m / 8000)) / (287.05 * virtual_temp);
+  double density_tropo = (100* pressure_mb * exp ((-1 * altitude_tropo_top_m) / 8000)) /( 287.05 * virtual_temp);
+
+  density_tropo_avg_kgm3 = ((density_slugft3 * 515.379) + density_half + density_tropo) / 3;
+}
+
+void
+FGEnvironment::_recalc_relative_humidity ()
+{
+  double vaporpressure = 6.11 * pow ( 10, ((7.5 * dewpoint_degc) /( 237.7 + dewpoint_degc)));
+  double sat_vaporpressure = 6.11 * pow ( 10, ((7.5 * temperature_degc) /( 237.7 + temperature_degc)) );
+  relative_humidity = 100 *vaporpressure / sat_vaporpressure ;
 }
 
 
-
+
 ////////////////////////////////////////////////////////////////////////
 // Functions.
 ////////////////////////////////////////////////////////////////////////

src/Environment/environment.hxx

@@ -65,6 +65,11 @@ public:
   virtual double get_pressure_inhg () const;
   virtual double get_density_slugft3 () const;
 
+  virtual double get_relative_humidity () const;
+  virtual double get_density_tropo_avg_kgm3 () const;
+  virtual double get_altitude_half_to_sun_m () const;
+  virtual double get_altitude_tropo_top_m () const;
+
   virtual double get_wind_from_heading_deg () const;
   virtual double get_wind_speed_kt () const;
   virtual double get_wind_from_north_fps () const;
@@ -94,6 +99,8 @@ public:
 
   virtual double get_elevation_ft () const;
   virtual void set_elevation_ft (double elevation_ft);
+  virtual void set_altitude_half_to_sun_m (double alt);
+  virtual void set_altitude_tropo_top_m (double alt);
 
 private:
 
@@ -108,11 +115,13 @@ private:
   void _recalc_alt_pressure ();
   void _recalc_density ();
 
-  double elevation_ft;
+  void _recalc_density_tropo_avg_kgm3 ();
+  void _recalc_relative_humidity ();
 
+  double elevation_ft;
   double visibility_m;
 
-				// Atmosphere
+  // Atmosphere
   double temperature_sea_level_degc;
   double temperature_degc;
   double dewpoint_sea_level_degc;
@@ -121,6 +130,11 @@ private:
   double pressure_inhg;
   double density_slugft3;
 
+  double density_tropo_avg_kgm3;
+  double relative_humidity;
+  double altitude_half_to_sun_m;
+  double altitude_tropo_top_m;
+
   double turbulence_magnitude_norm;
   double turbulence_rate_hz;
 

src/Environment/environment_mgr.cxx

@@ -108,6 +108,16 @@ FGEnvironmentMgr::bind ()
 	&FGEnvironment::get_pressure_inhg); // FIXME: read-only for now
   fgTie("/environment/density-slugft3", _environment,
 	&FGEnvironment::get_density_slugft3); // read-only
+  fgTie("/environment/relative-humidity", _environment,
+	&FGEnvironment::get_relative_humidity); //ro
+  fgTie("/environment/atmosphere/density-tropo-avg", _environment,
+	&FGEnvironment::get_density_tropo_avg_kgm3); //ro
+  fgTie("/environment/atmosphere/altitude-half-to-sun", _environment,
+	&FGEnvironment::get_altitude_half_to_sun_m, 
+	&FGEnvironment::set_altitude_half_to_sun_m);
+  fgTie("/environment/atmosphere/altitude-troposphere-top", _environment,
+        &FGEnvironment::get_altitude_tropo_top_m,
+        &FGEnvironment::set_altitude_tropo_top_m);
   fgTie("/environment/wind-from-heading-deg", _environment,
 	&FGEnvironment::get_wind_from_heading_deg,
 	&FGEnvironment::set_wind_from_heading_deg);
@@ -203,9 +213,13 @@ FGEnvironmentMgr::unbind ()
   fgUntie("/environment/pressure-sea-level-inhg");
   fgUntie("/environment/pressure-inhg");
   fgUntie("/environment/density-inhg");
+  fgUntie("/environment/relative_humidity");
+  fgUntie("/environment/atmosphere/density_tropo_avg");
   fgUntie("/environment/wind-from-north-fps");
   fgUntie("/environment/wind-from-east-fps");
   fgUntie("/environment/wind-from-down-fps");
+  fgUntie("/environment/atmosphere/altitude_half_to_sun");
+  fgUntie("/environment/atmosphere/altitude_troposphere_top");
   for (int i = 0; i < MAX_CLOUD_LAYERS; i++) {
     char buf[128];
     sprintf(buf, "/environment/clouds/layer[%d]/span-m", i);

src/Main/main.cxx

@@ -808,7 +808,8 @@ static void fgIdleFunction ( void ) {
                        globals->get_ephem()->getNumPlanets(), 
                        globals->get_ephem()->getPlanets(),
                        globals->get_ephem()->getNumStars(),
-                       globals->get_ephem()->getStars() );
+                       globals->get_ephem()->getStars(),
+		       fgGetNode("/environment", true));
 
         // Initialize MagVar model
         SGMagVar *magvar = new SGMagVar();

src/Main/renderer.cxx

@@ -362,6 +362,43 @@ FGRenderer::update( bool refresh_camera_settings ) {
 
     // update the sky dome
     if ( skyblend ) {
+
+        // The sun and moon distances are scaled down versions
+        // of the actual distance to get both the moon and the sun
+        // within the range of the far clip plane.
+        // Moon distance:    384,467 kilometers
+        // Sun distance: 150,000,000 kilometers
+
+        double sun_horiz_eff, moon_horiz_eff;
+        if (fgGetBool("/sim/rendering/horizon-effect")) {
+           sun_horiz_eff = 0.67+pow(0.5+cos(l->get_sun_angle())*2/2, 0.33)/3;
+           moon_horiz_eff = 0.67+pow(0.5+cos(l->get_moon_angle())*2/2, 0.33)/3;
+        } else {
+           sun_horiz_eff = moon_horiz_eff = 1.0;
+        }
+
+        static SGSkyState sstate;
+
+        sstate.view_pos  = current__view->get_view_pos();
+        sstate.zero_elev = current__view->get_zero_elev();
+        sstate.view_up   = current__view->get_world_up();
+        sstate.lon       = current__view->getLongitude_deg()
+                            * SGD_DEGREES_TO_RADIANS;
+        sstate.lat       = current__view->getLatitude_deg()
+                            * SGD_DEGREES_TO_RADIANS;
+        sstate.alt       = current__view->getAltitudeASL_ft()
+                            * SG_FEET_TO_METER;
+        sstate.spin      = l->get_sun_rotation();
+        sstate.gst       = globals->get_time_params()->getGst();
+        sstate.sun_ra    = globals->get_ephem()->getSunRightAscension();
+        sstate.sun_dec   = globals->get_ephem()->getSunDeclination();
+        sstate.sun_dist  = 50000.0 * sun_horiz_eff;
+        sstate.moon_ra   = globals->get_ephem()->getMoonRightAscension();
+        sstate.moon_dec  = globals->get_ephem()->getMoonDeclination();
+        sstate.moon_dist = 40000.0 * moon_horiz_eff;
+        sstate.sun_angle = l->get_sun_angle();
+
+
         /*
          SG_LOG( SG_GENERAL, SG_BULK, "thesky->repaint() sky_color = "
          << l->sky_color()[0] << " "
@@ -391,6 +428,7 @@ FGRenderer::update( bool refresh_camera_settings ) {
         scolor.planet_data = globals->get_ephem()->getPlanets();
         scolor.star_data   = globals->get_ephem()->getStars();
 
+        thesky->reposition( sstate, delta_time_sec );
         thesky->repaint( scolor );
 
         /*
@@ -412,41 +450,6 @@ FGRenderer::update( bool refresh_camera_settings ) {
           << " moon dec = " << globals->get_ephem()->getMoonDeclination() );
         */
 
-        // The sun and moon distances are scaled down versions
-        // of the actual distance to get both the moon and the sun
-        // within the range of the far clip plane.
-        // Moon distance:    384,467 kilometers
-        // Sun distance: 150,000,000 kilometers
-        double sun_horiz_eff, moon_horiz_eff;
-        if (fgGetBool("/sim/rendering/horizon-effect")) {
-        sun_horiz_eff = 0.67+pow(0.5+cos(l->get_sun_angle())*2/2, 0.33)/3;
-        moon_horiz_eff = 0.67+pow(0.5+cos(l->get_moon_angle())*2/2, 0.33)/3;
-        } else {
-           sun_horiz_eff = moon_horiz_eff = 1.0;
-        }
-
-        static SGSkyState sstate;
-
-        sstate.view_pos  = current__view->get_view_pos();
-        sstate.zero_elev = current__view->get_zero_elev();
-        sstate.view_up   = current__view->get_world_up();
-        sstate.lon       = current__view->getLongitude_deg()
-                            * SGD_DEGREES_TO_RADIANS;
-        sstate.lat       = current__view->getLatitude_deg()
-                            * SGD_DEGREES_TO_RADIANS;
-        sstate.alt       = current__view->getAltitudeASL_ft()
-                            * SG_FEET_TO_METER;
-        sstate.spin      = l->get_sun_rotation();
-        sstate.gst       = globals->get_time_params()->getGst();
-        sstate.sun_ra    = globals->get_ephem()->getSunRightAscension();
-        sstate.sun_dec   = globals->get_ephem()->getSunDeclination();
-        sstate.sun_dist  = 50000.0 * sun_horiz_eff;
-        sstate.moon_ra   = globals->get_ephem()->getMoonRightAscension();
-        sstate.moon_dec  = globals->get_ephem()->getMoonDeclination();
-        sstate.moon_dist = 40000.0 * moon_horiz_eff;
-
-        thesky->reposition( sstate, delta_time_sec );
-
         shadows->setupShadows(
           current__view->getLongitude_deg(),
           current__view->getLatitude_deg(),
@@ -454,6 +457,7 @@ FGRenderer::update( bool refresh_camera_settings ) {
           globals->get_ephem()->getSunRightAscension(),
           globals->get_ephem()->getSunDeclination(),
           l->get_sun_angle());
+
     }
 
     glEnable( GL_DEPTH_TEST );