//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
-// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
-// $Id$
-
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
-#ifdef HAVE_WINDOWS_H
-# include <windows.h>
-#endif
-
#include <math.h>
-#include <plib/sg.h>
+#include <boost/tuple/tuple.hpp>
-#include <simgear/constants.h>
-#include <simgear/debug/logstream.hxx>
-#include <simgear/math/interpolater.hxx>
+#include <simgear/props/props.hxx>
+#include <simgear/math/SGMath.hxx>
#include <Main/fg_props.hxx>
-#include "environment.hxx"
+#include "environment.hxx"
+#include "atmosphere.hxx"
\f
////////////////////////////////////////////////////////////////////////
// Atmosphere model.
////////////////////////////////////////////////////////////////////////
-// Copied from YASim Atmosphere.cxx, with m converted to ft, degK
-// converted to degC, Pa converted to inHG, and kg/m^3 converted to
-// slug/ft^3; they were then converted to deltas from the sea-level
-// defaults (approx. 15degC, 29.92inHG, and 0.00237slugs/ft^3).
+#ifdef USING_TABLES
-// Original comment from YASim:
+// Calculated based on the ISA standard day, as found at e.g.
+// http://www.av8n.com/physics/altimetry.htm
-// Copied from McCormick, who got it from "The ARDC Model Atmosphere"
-// Note that there's an error in the text in the first entry,
-// McCormick lists 299.16/101325/1.22500, but those don't agree with
-// R=287. I chose to correct the temperature to 288.20, since 79F is
-// pretty hot for a "standard" atmosphere.
-
-// Elevation (ft), temperature factor (degK), pressure factor (inHG)
+// Each line of data has 3 elements:
+// Elevation (ft),
+// temperature factor (dimensionless ratio of absolute temp),
+// pressure factor (dimensionless ratio)
static double atmosphere_data[][3] = {
- { 0.00, 1.00, 1.000 },
- { 2952.76, 0.98, 0.898 },
- { 5905.51, 0.96, 0.804 },
- { 8858.27, 0.94, 0.719 },
- { 11811.02, 0.92, 0.641 },
- { 14763.78, 0.90, 0.570 },
- { 17716.54, 0.88, 0.506 },
- { 20669.29, 0.86, 0.447 },
- { 23622.05, 0.84, 0.394 },
- { 26574.80, 0.82, 0.347 },
- { 29527.56, 0.80, 0.304 },
- { 32480.31, 0.78, 0.266 },
- { 35433.07, 0.76, 0.231 },
- { 38385.83, 0.75, 0.201 },
- { 41338.58, 0.75, 0.174 },
- { 44291.34, 0.75, 0.151 },
- { 47244.09, 0.75, 0.131 },
- { 50196.85, 0.75, 0.114 },
- { 53149.61, 0.75, 0.099 },
- { 56102.36, 0.75, 0.086 },
- { 59055.12, 0.75, 0.075 },
- { 62007.87, 0.75, 0.065 },
+ { -3000.00, 1.021, 1.1133 },
+ { 0.00, 1.000, 1.0000 },
+ { 2952.76, 0.980, 0.8978 },
+ { 5905.51, 0.959, 0.8042 },
+ { 8858.27, 0.939, 0.7187 },
+ { 11811.02, 0.919, 0.6407 },
+ { 14763.78, 0.898, 0.5697 },
+ { 17716.54, 0.878, 0.5052 },
+ { 20669.29, 0.858, 0.4468 },
+ { 23622.05, 0.838, 0.3940 },
+ { 26574.80, 0.817, 0.3463 },
+ { 29527.56, 0.797, 0.3034 },
+ { 32480.31, 0.777, 0.2649 },
+ { 35433.07, 0.756, 0.2305 },
+ { 38385.83, 0.752, 0.2000 },
+ { 41338.58, 0.752, 0.1736 },
+ { 44291.34, 0.752, 0.1506 },
+ { 47244.09, 0.752, 0.1307 },
+ { 50196.85, 0.752, 0.1134 },
+ { 53149.61, 0.752, 0.0984 },
+ { 56102.36, 0.752, 0.0854 },
+ { 59055.12, 0.752, 0.0741 },
+ { 62007.87, 0.752, 0.0643 },
+ { 65000.00, 0.752, 0.0557 },
+ { 68000.00, 0.754, 0.0482 },
+ { 71000.00, 0.758, 0.0418 },
+ { 74000.00, 0.761, 0.0362 },
+ { 77000.00, 0.764, 0.0314 },
+ { 80000.00, 0.767, 0.0273 },
+ { 83000.00, 0.770, 0.0237 },
+ { 86000.00, 0.773, 0.0206 },
+ { 89000.00, 0.777, 0.0179 },
+ { 92000.00, 0.780, 0.0156 },
+ { 95000.00, 0.783, 0.0135 },
+ { 98000.00, 0.786, 0.0118 },
+ { 101000.00, 0.789, 0.0103 },
{ -1, -1, -1 }
};
atmosphere_data[i][2]);
}
}
-
+#endif
\f
////////////////////////////////////////////////////////////////////////
// Implementation of FGEnvironment.
////////////////////////////////////////////////////////////////////////
+void FGEnvironment::_init()
+{
+ live_update = false;
+ elevation_ft = 0;
+ visibility_m = 32000;
+ temperature_sea_level_degc = 15;
+ temperature_degc = 15;
+ dewpoint_sea_level_degc = 5; // guess
+ dewpoint_degc = 5;
+ pressure_sea_level_inhg = 29.92;
+ pressure_inhg = 29.92;
+ density_slugft3 = 0;
+ turbulence_magnitude_norm = 0;
+ turbulence_rate_hz = 1;
+ wind_from_heading_deg = 0;
+ wind_speed_kt = 0;
+ wind_from_north_fps = 0;
+ wind_from_east_fps = 0;
+ wind_from_down_fps = 0;
+ altitude_half_to_sun_m = 1000;
+ altitude_tropo_top_m = 10000;
+#ifdef USING_TABLES
+ _setup_tables();
+#endif
+ _recalc_density();
+ _recalc_relative_humidity();
+ live_update = true;
+}
+
FGEnvironment::FGEnvironment()
- : elevation_ft(0),
- visibility_m(32000),
- temperature_sea_level_degc(15),
- temperature_degc(15),
- dewpoint_sea_level_degc(5), // guess
- dewpoint_degc(5),
- pressure_sea_level_inhg(29.92),
- pressure_inhg(29.92),
- turbulence_magnitude_norm(0),
- turbulence_rate_hz(1),
- wind_from_heading_deg(0),
- wind_speed_kt(0),
- wind_from_north_fps(0),
- wind_from_east_fps(0),
- wind_from_down_fps(0)
-{
- _setup_tables();
- _recalc_density();
+{
+ _init();
}
FGEnvironment::FGEnvironment (const FGEnvironment &env)
{
- FGEnvironment();
+ _init();
copy(env);
}
FGEnvironment::~FGEnvironment()
{
+ Untie();
+}
+
+FGEnvironment & FGEnvironment::operator = ( const FGEnvironment & other )
+{
+ copy( other );
+ return *this;
}
void
wind_from_down_fps = env.wind_from_down_fps;
turbulence_magnitude_norm = env.turbulence_magnitude_norm;
turbulence_rate_hz = env.turbulence_rate_hz;
+ pressure_inhg = env.pressure_inhg;
+ density_slugft3 = env.density_slugft3;
+ density_tropo_avg_kgm3 = env.density_tropo_avg_kgm3;
+ relative_humidity = env.relative_humidity;
+ altitude_half_to_sun_m = env.altitude_half_to_sun_m;
+ altitude_tropo_top_m = env.altitude_tropo_top_m;
+ live_update = env.live_update;
}
static inline bool
void
FGEnvironment::read (const SGPropertyNode * node)
{
+ bool live_update = set_live_update( false );
maybe_copy_value(this, node, "visibility-m",
&FGEnvironment::set_visibility_m);
+ maybe_copy_value(this, node, "elevation-ft",
+ &FGEnvironment::set_elevation_ft);
+
if (!maybe_copy_value(this, node, "temperature-sea-level-degc",
- &FGEnvironment::set_temperature_sea_level_degc))
- maybe_copy_value(this, node, "temperature-degc",
- &FGEnvironment::set_temperature_degc);
+ &FGEnvironment::set_temperature_sea_level_degc)) {
+ if( maybe_copy_value(this, node, "temperature-degc",
+ &FGEnvironment::set_temperature_degc)) {
+ _recalc_sl_temperature();
+ }
+ }
if (!maybe_copy_value(this, node, "dewpoint-sea-level-degc",
- &FGEnvironment::set_dewpoint_sea_level_degc))
- maybe_copy_value(this, node, "dewpoint-degc",
- &FGEnvironment::set_dewpoint_degc);
+ &FGEnvironment::set_dewpoint_sea_level_degc)) {
+ if( maybe_copy_value(this, node, "dewpoint-degc",
+ &FGEnvironment::set_dewpoint_degc)) {
+ _recalc_sl_dewpoint();
+ }
+ }
if (!maybe_copy_value(this, node, "pressure-sea-level-inhg",
- &FGEnvironment::set_pressure_sea_level_inhg))
- maybe_copy_value(this, node, "pressure-inhg",
- &FGEnvironment::set_pressure_inhg);
+ &FGEnvironment::set_pressure_sea_level_inhg)) {
+ if( maybe_copy_value(this, node, "pressure-inhg",
+ &FGEnvironment::set_pressure_inhg)) {
+ _recalc_sl_pressure();
+ }
+ }
maybe_copy_value(this, node, "wind-from-heading-deg",
&FGEnvironment::set_wind_from_heading_deg);
maybe_copy_value(this, node, "wind-speed-kt",
&FGEnvironment::set_wind_speed_kt);
- maybe_copy_value(this, node, "elevation-ft",
- &FGEnvironment::set_elevation_ft);
-
maybe_copy_value(this, node, "turbulence/magnitude-norm",
&FGEnvironment::set_turbulence_magnitude_norm);
maybe_copy_value(this, node, "turbulence/rate-hz",
&FGEnvironment::set_turbulence_rate_hz);
+
+ // calculate derived properties here to avoid duplicate expensive computations
+ _recalc_ne();
+ _recalc_alt_pt();
+ _recalc_alt_dewpoint();
+ _recalc_density();
+ _recalc_relative_humidity();
+
+ set_live_update(live_update);
}
+void FGEnvironment::Tie( SGPropertyNode_ptr base, bool archivable )
+{
+ _tiedProperties.setRoot( base );
+
+ _tiedProperties.Tie( "visibility-m", this,
+ &FGEnvironment::get_visibility_m,
+ &FGEnvironment::set_visibility_m);
+
+ _tiedProperties.Tie("temperature-sea-level-degc", this,
+ &FGEnvironment::get_temperature_sea_level_degc,
+ &FGEnvironment::set_temperature_sea_level_degc);
+
+ _tiedProperties.Tie("temperature-degc", this,
+ &FGEnvironment::get_temperature_degc,
+ &FGEnvironment::set_temperature_degc);
+
+ _tiedProperties.Tie("dewpoint-sea-level-degc", this,
+ &FGEnvironment::get_dewpoint_sea_level_degc,
+ &FGEnvironment::set_dewpoint_sea_level_degc);
+
+ _tiedProperties.Tie("dewpoint-degc", this,
+ &FGEnvironment::get_dewpoint_degc,
+ &FGEnvironment::set_dewpoint_degc);
+
+ _tiedProperties.Tie("pressure-sea-level-inhg", this,
+ &FGEnvironment::get_pressure_sea_level_inhg,
+ &FGEnvironment::set_pressure_sea_level_inhg);
+
+ _tiedProperties.Tie("pressure-inhg", this,
+ &FGEnvironment::get_pressure_inhg,
+ &FGEnvironment::set_pressure_inhg);
+
+ _tiedProperties.Tie("atmosphere/altitude-half-to-sun", this,
+ &FGEnvironment::get_altitude_half_to_sun_m,
+ &FGEnvironment::set_altitude_half_to_sun_m);
+
+ _tiedProperties.Tie("atmosphere/altitude-troposphere-top", this,
+ &FGEnvironment::get_altitude_tropo_top_m,
+ &FGEnvironment::set_altitude_tropo_top_m);
+
+ _tiedProperties.Tie("wind-from-heading-deg", this,
+ &FGEnvironment::get_wind_from_heading_deg,
+ &FGEnvironment::set_wind_from_heading_deg);
+
+ _tiedProperties.Tie("wind-speed-kt", this,
+ &FGEnvironment::get_wind_speed_kt,
+ &FGEnvironment::set_wind_speed_kt);
+
+ _tiedProperties.Tie("wind-from-north-fps", this,
+ &FGEnvironment::get_wind_from_north_fps,
+ &FGEnvironment::set_wind_from_north_fps);
+
+ _tiedProperties.Tie("wind-from-east-fps", this,
+ &FGEnvironment::get_wind_from_east_fps,
+ &FGEnvironment::set_wind_from_east_fps);
+
+ _tiedProperties.Tie("wind-from-down-fps", this,
+ &FGEnvironment::get_wind_from_down_fps,
+ &FGEnvironment::set_wind_from_down_fps);
+
+ _tiedProperties.Tie("turbulence/magnitude-norm", this,
+ &FGEnvironment::get_turbulence_magnitude_norm,
+ &FGEnvironment::set_turbulence_magnitude_norm);
+
+ _tiedProperties.Tie("turbulence/rate-hz", this,
+ &FGEnvironment::get_turbulence_rate_hz,
+ &FGEnvironment::set_turbulence_rate_hz);
+
+ _tiedProperties.setAttribute( SGPropertyNode::ARCHIVE, archivable );
+
+ _tiedProperties.Tie("temperature-degf", this,
+ &FGEnvironment::get_temperature_degf);
+
+ _tiedProperties.Tie("density-slugft3", this,
+ &FGEnvironment::get_density_slugft3); // read-only
+
+ _tiedProperties.Tie("relative-humidity", this,
+ &FGEnvironment::get_relative_humidity); //ro
+
+ _tiedProperties.Tie("atmosphere/density-tropo-avg", this,
+ &FGEnvironment::get_density_tropo_avg_kgm3); //ro
+}
+
+void FGEnvironment::Untie()
+{
+ _tiedProperties.Untie();
+}
double
FGEnvironment::get_visibility_m () const
return temperature_degc;
}
+double
+FGEnvironment::get_temperature_degf () const
+{
+ return (temperature_degc * 9.0 / 5.0) + 32.0;
+}
+
double
FGEnvironment::get_dewpoint_sea_level_degc () 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
{
temperature_sea_level_degc = t;
if (dewpoint_sea_level_degc > t)
dewpoint_sea_level_degc = t;
- _recalc_alt_temperature();
- _recalc_density();
+ if( live_update ) {
+ _recalc_alt_pt();
+ _recalc_density();
+ }
}
void
FGEnvironment::set_temperature_degc (double t)
{
temperature_degc = t;
- _recalc_sl_temperature();
- _recalc_density();
+ if( live_update ) {
+ _recalc_sl_temperature();
+ _recalc_sl_pressure();
+ _recalc_alt_pt();
+ _recalc_density();
+ _recalc_relative_humidity();
+ }
}
void
dewpoint_sea_level_degc = t;
if (temperature_sea_level_degc < t)
temperature_sea_level_degc = t;
- _recalc_alt_dewpoint();
- _recalc_density();
+ if( live_update ) {
+ _recalc_alt_dewpoint();
+ _recalc_density();
+ }
}
void
FGEnvironment::set_dewpoint_degc (double t)
{
dewpoint_degc = t;
- _recalc_sl_dewpoint();
- _recalc_density();
+ if( live_update ) {
+ _recalc_sl_dewpoint();
+ _recalc_density();
+ _recalc_relative_humidity();
+ }
}
void
FGEnvironment::set_pressure_sea_level_inhg (double p)
{
pressure_sea_level_inhg = p;
- _recalc_alt_pressure();
- _recalc_density();
+ if( live_update ) {
+ _recalc_alt_pt();
+ _recalc_density();
+ }
}
void
FGEnvironment::set_pressure_inhg (double p)
{
pressure_inhg = p;
- _recalc_sl_pressure();
- _recalc_density();
+ if( live_update ) {
+ _recalc_sl_pressure();
+ _recalc_density();
+ }
}
void
FGEnvironment::set_wind_from_heading_deg (double h)
{
wind_from_heading_deg = h;
- _recalc_ne();
+ if( live_update ) {
+ _recalc_ne();
+ }
}
void
FGEnvironment::set_wind_speed_kt (double s)
{
wind_speed_kt = s;
- _recalc_ne();
+ if( live_update ) {
+ _recalc_ne();
+ }
}
void
FGEnvironment::set_wind_from_north_fps (double n)
{
wind_from_north_fps = n;
- _recalc_hdgspd();
+ if( live_update ) {
+ _recalc_hdgspd();
+ }
}
void
FGEnvironment::set_wind_from_east_fps (double e)
{
wind_from_east_fps = e;
- _recalc_hdgspd();
+ if( live_update ) {
+ _recalc_hdgspd();
+ }
}
void
FGEnvironment::set_wind_from_down_fps (double d)
{
wind_from_down_fps = d;
- _recalc_hdgspd();
+ if( live_update ) {
+ _recalc_hdgspd();
+ }
}
void
FGEnvironment::set_elevation_ft (double e)
{
elevation_ft = e;
- _recalc_alt_temperature();
- _recalc_alt_dewpoint();
- _recalc_alt_pressure();
- _recalc_density();
+ if( live_update ) {
+ _recalc_alt_pt();
+ _recalc_alt_dewpoint();
+ _recalc_density();
+ _recalc_relative_humidity();
+ }
}
void
-FGEnvironment::_recalc_hdgspd ()
+FGEnvironment::set_altitude_half_to_sun_m (double alt)
{
- double angle_rad;
+ altitude_half_to_sun_m = alt;
+ if( live_update ) {
+ _recalc_density_tropo_avg_kgm3();
+ }
+}
- if (wind_from_east_fps == 0) {
- angle_rad = (wind_from_north_fps >= 0 ? SGD_PI/2 : -SGD_PI/2);
- } else {
- angle_rad = atan(wind_from_north_fps/wind_from_east_fps);
+void
+FGEnvironment::set_altitude_tropo_top_m (double alt)
+{
+ altitude_tropo_top_m = alt;
+ if( live_update ) {
+ _recalc_density_tropo_avg_kgm3();
}
- wind_from_heading_deg = angle_rad * SGD_RADIANS_TO_DEGREES;
- if (wind_from_east_fps >= 0)
- wind_from_heading_deg = 90 - wind_from_heading_deg;
- else
- wind_from_heading_deg = 270 - wind_from_heading_deg;
+}
+
+
+void
+FGEnvironment::_recalc_hdgspd ()
+{
+ wind_from_heading_deg =
+ atan2(wind_from_east_fps, wind_from_north_fps) * SGD_RADIANS_TO_DEGREES;
+
+ if( wind_from_heading_deg < 0 )
+ wind_from_heading_deg += 360.0;
-#if 0
- // FIXME: Windspeed can become negative with these formulas.
- // which can cause problems for animations that rely
- // on the windspeed property.
- if (angle_rad == 0)
- wind_speed_kt = fabs(wind_from_east_fps
- * SG_METER_TO_NM * SG_FEET_TO_METER * 3600);
- else
- wind_speed_kt = (wind_from_north_fps / sin(angle_rad))
- * SG_METER_TO_NM * SG_FEET_TO_METER * 3600;
-#else
wind_speed_kt = sqrt(wind_from_north_fps * wind_from_north_fps +
wind_from_east_fps * wind_from_east_fps)
* SG_METER_TO_NM * SG_FEET_TO_METER * 3600;
-#endif
}
void
sin(wind_from_heading_deg * SGD_DEGREES_TO_RADIANS);
}
+// Intended to help with the interpretation of METAR data,
+// not for random in-flight outside-air temperatures.
void
FGEnvironment::_recalc_sl_temperature ()
{
- // If we're in the stratosphere, leave sea-level temp alone
- if (elevation_ft < 38000) {
- temperature_sea_level_degc =
- (temperature_degc + 273.15)
- /_temperature_degc_table->interpolate(elevation_ft)
- - 273.15;
+
+#if 0
+ {
+ SG_LOG(SG_ENVIRONMENT, SG_DEBUG, "recalc_sl_temperature: using "
+ << temperature_degc << " @ " << elevation_ft << " :: " << this);
}
-}
+#endif
-void
-FGEnvironment::_recalc_alt_temperature ()
-{
- if (elevation_ft < 38000) {
- temperature_degc =
- (temperature_sea_level_degc + 273.15) *
- _temperature_degc_table->interpolate(elevation_ft) - 273.15;
- } else {
- temperature_degc = -56.49; // Stratosphere is constant
+ if (elevation_ft * atmodel::foot >= ISA_def[1].height) {
+ SG_LOG(SG_ENVIRONMENT, SG_ALERT, "recalc_sl_temperature: "
+ << "valid only in troposphere, not " << elevation_ft);
+ return;
}
+
+// Clamp: temperature of the stratosphere, in degrees C:
+ double t_strato = ISA_def[1].temp - atmodel::freezing;
+ if (temperature_degc < t_strato) temperature_sea_level_degc = t_strato;
+ else temperature_sea_level_degc =
+ temperature_degc + elevation_ft * atmodel::foot * ISA_def[0].lapse;
+
+// Alternative implemenation:
+// else temperature_sea_level_inhg = T_layer(0., elevation_ft * foot,
+// pressure_inhg * inHg, temperature_degc + freezing, ISA_def[0].lapse) - freezing;
}
void
void
FGEnvironment::_recalc_sl_pressure ()
{
- pressure_sea_level_inhg =
- pressure_inhg / _pressure_inhg_table->interpolate(elevation_ft);
+ using namespace atmodel;
+#if 0
+ {
+ SG_LOG(SG_ENVIRONMENT, SG_ALERT, "recalc_sl_pressure: using "
+ << pressure_inhg << " and "
+ << temperature_degc << " @ " << elevation_ft << " :: " << this);
+ }
+#endif
+ pressure_sea_level_inhg = P_layer(0., elevation_ft * foot,
+ pressure_inhg * inHg, temperature_degc + freezing, ISA_def[0].lapse) / inHg;
}
+// This gets called at frame rate, to account for the aircraft's
+// changing altitude.
+// Called by set_elevation_ft() which is called by FGEnvironmentMgr::update
+
void
-FGEnvironment::_recalc_alt_pressure ()
+FGEnvironment::_recalc_alt_pt ()
{
- pressure_inhg =
- pressure_sea_level_inhg * _pressure_inhg_table->interpolate(elevation_ft);
+ using namespace atmodel;
+#if 0
+ {
+ static int count(0);
+ if (++count % 1000 == 0) {
+ SG_LOG(SG_ENVIRONMENT, SG_ALERT,
+ "recalc_alt_pt for: " << elevation_ft
+ << " using " << pressure_sea_level_inhg
+ << " and " << temperature_sea_level_degc
+ << " :: " << this
+ << " # " << count);
+ }
+ }
+#endif
+ double press = pressure_inhg * inHg;
+ double temp = temperature_degc + freezing;
+ boost::tie(press, temp) = PT_vs_hpt(elevation_ft * foot,
+ pressure_sea_level_inhg * inHg, temperature_sea_level_degc + freezing);
+ temperature_degc = temp - freezing;
+ pressure_inhg = press / inHg;
}
void
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(10.0, ((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(10.0, ((7.5 * dewpoint_degc) / ( 237.7 + dewpoint_degc)));
+ double sat_vaporpressure = 6.11 * pow(10.0, ((7.5 * temperature_degc)
+ / ( 237.7 + temperature_degc)) );
+ relative_humidity = 100 * vaporpressure / sat_vaporpressure ;
+
+ with a little algebra, this gets the same result and spares two multiplications and one pow()
+*/
+ double a = (7.5 * dewpoint_degc) / ( 237.7 + dewpoint_degc);
+ double b = (7.5 * temperature_degc) / ( 237.7 + temperature_degc);
+ relative_humidity = 100 * pow(10.0,a-b);
+}
+
+bool
+FGEnvironment::set_live_update( bool _live_update )
+{
+ bool b = live_update;
+ live_update = _live_update;
+ return b;
}
-\f
////////////////////////////////////////////////////////////////////////
// Functions.
////////////////////////////////////////////////////////////////////////
return fmod(do_interp(a, b, fraction), 360);
}
-void
-interpolate (const FGEnvironment * env1, const FGEnvironment * env2,
- double fraction, FGEnvironment * result)
+FGEnvironment &
+FGEnvironment::interpolate( const FGEnvironment & env2,
+ double fraction, FGEnvironment * result) const
{
+ // don't calculate each internal property every time we set a single value
+ // we trigger that at the end of the interpolation process
+ bool live_update = result->set_live_update( false );
+
result->set_visibility_m
- (do_interp(env1->get_visibility_m(),
- env2->get_visibility_m(),
+ (do_interp(get_visibility_m(),
+ env2.get_visibility_m(),
fraction));
result->set_temperature_sea_level_degc
- (do_interp(env1->get_temperature_sea_level_degc(),
- env2->get_temperature_sea_level_degc(),
+ (do_interp(get_temperature_sea_level_degc(),
+ env2.get_temperature_sea_level_degc(),
fraction));
- result->set_dewpoint_degc
- (do_interp(env1->get_dewpoint_sea_level_degc(),
- env2->get_dewpoint_sea_level_degc(),
+ result->set_dewpoint_sea_level_degc
+ (do_interp(get_dewpoint_sea_level_degc(),
+ env2.get_dewpoint_sea_level_degc(),
fraction));
result->set_pressure_sea_level_inhg
- (do_interp(env1->get_pressure_sea_level_inhg(),
- env2->get_pressure_sea_level_inhg(),
+ (do_interp(get_pressure_sea_level_inhg(),
+ env2.get_pressure_sea_level_inhg(),
fraction));
result->set_wind_from_heading_deg
- (do_interp_deg(env1->get_wind_from_heading_deg(),
- env2->get_wind_from_heading_deg(),
+ (do_interp_deg(get_wind_from_heading_deg(),
+ env2.get_wind_from_heading_deg(),
fraction));
result->set_wind_speed_kt
- (do_interp(env1->get_wind_speed_kt(),
- env2->get_wind_speed_kt(),
+ (do_interp(get_wind_speed_kt(),
+ env2.get_wind_speed_kt(),
fraction));
result->set_elevation_ft
- (do_interp(env1->get_elevation_ft(),
- env2->get_elevation_ft(),
+ (do_interp(get_elevation_ft(),
+ env2.get_elevation_ft(),
fraction));
result->set_turbulence_magnitude_norm
- (do_interp(env1->get_turbulence_magnitude_norm(),
- env2->get_turbulence_magnitude_norm(),
+ (do_interp(get_turbulence_magnitude_norm(),
+ env2.get_turbulence_magnitude_norm(),
fraction));
result->set_turbulence_rate_hz
- (do_interp(env1->get_turbulence_rate_hz(),
- env2->get_turbulence_rate_hz(),
+ (do_interp(get_turbulence_rate_hz(),
+ env2.get_turbulence_rate_hz(),
fraction));
+
+ // calculate derived properties here to avoid duplicate expensive computations
+ result->_recalc_ne();
+ result->_recalc_alt_pt();
+ result->_recalc_alt_dewpoint();
+ result->_recalc_density();
+ result->_recalc_relative_humidity();
+
+ result->set_live_update(live_update);
+
+ return *result;
}
// end of environment.cxx
projects / flightgear.git / blobdiff