X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FEnvironment%2Fenvironment.cxx;h=47e4d061f58959d27868c5e4c0fadd92454c8888;hb=79e48829da50e0103e81684896b8287bfe23cc96;hp=75adb24a3bc642e77a72b71fdc9f2bc7559c50a2;hpb=2df334378f35029daf700b268649c680e380f54d;p=flightgear.git diff --git a/src/Environment/environment.cxx b/src/Environment/environment.cxx index 75adb24a3..47e4d061f 100644 --- a/src/Environment/environment.cxx +++ b/src/Environment/environment.cxx @@ -41,14 +41,88 @@ #include "environment.hxx" + +//////////////////////////////////////////////////////////////////////// +// 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). + +// Original comment from YASim: + +// 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) +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 }, + { -1, -1, -1 } +}; + +static SGInterpTable * _temperature_degc_table = 0; +static SGInterpTable * _pressure_inhg_table = 0; + +static void +_setup_tables () +{ + if (_temperature_degc_table != 0) + return; + + _temperature_degc_table = new SGInterpTable; + _pressure_inhg_table = new SGInterpTable; + + for (int i = 0; atmosphere_data[i][0] != -1; i++) { + _temperature_degc_table->addEntry(atmosphere_data[i][0], + atmosphere_data[i][1]); + _pressure_inhg_table->addEntry(atmosphere_data[i][0], + atmosphere_data[i][2]); + } +} + + + +//////////////////////////////////////////////////////////////////////// +// Implementation of FGEnvironment. +//////////////////////////////////////////////////////////////////////// + FGEnvironment::FGEnvironment() - : _temperature_degc_table(new SGInterpTable), - _pressure_inhg_table(new SGInterpTable), - _density_slugft3_table(new SGInterpTable), + : elevation_ft(0), visibility_m(32000), - temperature_sea_level_degc(20), + temperature_sea_level_degc(15), + temperature_degc(15), + dewpoint_sea_level_degc(5), // guess + dewpoint_degc(5), pressure_sea_level_inhg(29.92), - density_sea_level_slugft3(0.00237), + 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), @@ -56,31 +130,89 @@ FGEnvironment::FGEnvironment() wind_from_down_fps(0) { _setup_tables(); + _recalc_density(); } FGEnvironment::FGEnvironment (const FGEnvironment &env) - : _temperature_degc_table(new SGInterpTable), - _pressure_inhg_table(new SGInterpTable), - _density_slugft3_table(new SGInterpTable), - elevation_ft(env.elevation_ft), - visibility_m(env.visibility_m), - temperature_sea_level_degc(env.temperature_sea_level_degc), - pressure_sea_level_inhg(env.pressure_sea_level_inhg), - density_sea_level_slugft3(env.density_sea_level_slugft3), - wind_from_heading_deg(env.wind_from_heading_deg), - wind_speed_kt(env.wind_speed_kt), - wind_from_north_fps(env.wind_from_north_fps), - wind_from_east_fps(env.wind_from_east_fps), - wind_from_down_fps(env.wind_from_down_fps) { - _setup_tables(); + FGEnvironment(); + copy(env); } FGEnvironment::~FGEnvironment() { - delete _temperature_degc_table; - delete _pressure_inhg_table; - delete _density_slugft3_table; +} + +void +FGEnvironment::copy (const FGEnvironment &env) +{ + elevation_ft = env.elevation_ft; + visibility_m = env.visibility_m; + temperature_sea_level_degc = env.temperature_sea_level_degc; + temperature_degc = env.temperature_degc; + dewpoint_sea_level_degc = env.dewpoint_sea_level_degc; + dewpoint_degc = env.dewpoint_degc; + pressure_sea_level_inhg = env.pressure_sea_level_inhg; + wind_from_heading_deg = env.wind_from_heading_deg; + wind_speed_kt = env.wind_speed_kt; + wind_from_north_fps = env.wind_from_north_fps; + wind_from_east_fps = env.wind_from_east_fps; + wind_from_down_fps = env.wind_from_down_fps; + turbulence_magnitude_norm = env.turbulence_magnitude_norm; + turbulence_rate_hz = env.turbulence_rate_hz; +} + +static inline bool +maybe_copy_value (FGEnvironment * env, const SGPropertyNode * node, + const char * name, void (FGEnvironment::*setter)(double)) +{ + const SGPropertyNode * child = node->getNode(name); + // fragile: depends on not being typed + // as a number + if (child != 0 && child->hasValue() && + child->getStringValue()[0] != '\0') { + (env->*setter)(child->getDoubleValue()); + return true; + } else { + return false; + } +} + +void +FGEnvironment::read (const SGPropertyNode * node) +{ + maybe_copy_value(this, node, "visibility-m", + &FGEnvironment::set_visibility_m); + + 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); + + 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); + + 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); + + 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); } @@ -103,21 +235,27 @@ FGEnvironment::get_temperature_degc () const } double -FGEnvironment::get_pressure_sea_level_inhg () const +FGEnvironment::get_dewpoint_sea_level_degc () const { - return pressure_sea_level_inhg; + return dewpoint_sea_level_degc; } double -FGEnvironment::get_pressure_inhg () const +FGEnvironment::get_dewpoint_degc () const { - return pressure_inhg; + return dewpoint_degc; +} + +double +FGEnvironment::get_pressure_sea_level_inhg () const +{ + return pressure_sea_level_inhg; } double -FGEnvironment::get_density_sea_level_slugft3 () const +FGEnvironment::get_pressure_inhg () const { - return density_sea_level_slugft3; + return pressure_inhg; } double @@ -156,6 +294,18 @@ FGEnvironment::get_wind_from_down_fps () const return wind_from_down_fps; } +double +FGEnvironment::get_turbulence_magnitude_norm () const +{ + return turbulence_magnitude_norm; +} + +double +FGEnvironment::get_turbulence_rate_hz () const +{ + return turbulence_rate_hz; +} + double FGEnvironment::get_elevation_ft () const { @@ -172,7 +322,10 @@ void FGEnvironment::set_temperature_sea_level_degc (double t) { temperature_sea_level_degc = t; + if (dewpoint_sea_level_degc > t) + dewpoint_sea_level_degc = t; _recalc_alt_temperature(); + _recalc_density(); } void @@ -180,34 +333,41 @@ FGEnvironment::set_temperature_degc (double t) { temperature_degc = t; _recalc_sl_temperature(); + _recalc_density(); } void -FGEnvironment::set_pressure_sea_level_inhg (double p) +FGEnvironment::set_dewpoint_sea_level_degc (double t) { - pressure_sea_level_inhg = p; - _recalc_alt_pressure(); + dewpoint_sea_level_degc = t; + if (temperature_sea_level_degc < t) + temperature_sea_level_degc = t; + _recalc_alt_dewpoint(); + _recalc_density(); } void -FGEnvironment::set_pressure_inhg (double p) +FGEnvironment::set_dewpoint_degc (double t) { - pressure_inhg = p; - _recalc_sl_pressure(); + dewpoint_degc = t; + _recalc_sl_dewpoint(); + _recalc_density(); } void -FGEnvironment::set_density_sea_level_slugft3 (double d) +FGEnvironment::set_pressure_sea_level_inhg (double p) { - density_sea_level_slugft3 = d; - _recalc_alt_density(); + pressure_sea_level_inhg = p; + _recalc_alt_pressure(); + _recalc_density(); } void -FGEnvironment::set_density_slugft3 (double d) +FGEnvironment::set_pressure_inhg (double p) { - density_slugft3 = d; - _recalc_sl_density(); + pressure_inhg = p; + _recalc_sl_pressure(); + _recalc_density(); } void @@ -246,68 +406,25 @@ FGEnvironment::set_wind_from_down_fps (double d) } void -FGEnvironment::set_elevation_ft (double e) +FGEnvironment::set_turbulence_magnitude_norm (double t) { - elevation_ft = e; - _recalc_alt_temperature(); - _recalc_alt_pressure(); - _recalc_alt_density(); + turbulence_magnitude_norm = t; } -// 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). - -// Original comment from YASim: - -// 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), -// density factor (slug/ft^3) -static double atmosphere_data[][4] = { - 0.00, 1.00, 1.000, 1.000000, - 2952.76, 0.98, 0.898, 0.916408, - 5905.51, 0.96, 0.804, 0.838286, - 8858.27, 0.94, 0.719, 0.765429, - 11811.02, 0.92, 0.641, 0.697510, - 14763.78, 0.90, 0.570, 0.634318, - 17716.54, 0.88, 0.506, 0.575616, - 20669.29, 0.86, 0.447, 0.521184, - 23622.05, 0.84, 0.394, 0.470784, - 26574.80, 0.82, 0.347, 0.424220, - 29527.56, 0.80, 0.304, 0.381273, - 32480.31, 0.78, 0.266, 0.341747, - 35433.07, 0.76, 0.231, 0.305445, - 38385.83, 0.75, 0.201, 0.266931, - 41338.58, 0.75, 0.174, 0.231739, - 44291.34, 0.75, 0.151, 0.201192, - 47244.09, 0.75, 0.131, 0.174686, - 50196.85, 0.75, 0.114, 0.151673, - 53149.61, 0.75, 0.099, 0.131698, - 56102.36, 0.75, 0.086, 0.114359, - 59055.12, 0.75, 0.075, 0.099306, - 62007.87, 0.75, 0.065, 0.086237, - -1, -1, -1, -1 -}; +void +FGEnvironment::set_turbulence_rate_hz (double r) +{ + turbulence_rate_hz = r; +} void -FGEnvironment::_setup_tables () +FGEnvironment::set_elevation_ft (double e) { - for (int i = 0; atmosphere_data[i][0] != -1; i++) { - _temperature_degc_table->addEntry(atmosphere_data[i][0], - atmosphere_data[i][1]); - _pressure_inhg_table->addEntry(atmosphere_data[i][0], - atmosphere_data[i][2]); - _density_slugft3_table->addEntry(atmosphere_data[i][0], - atmosphere_data[i][3]); - } + elevation_ft = e; + _recalc_alt_temperature(); + _recalc_alt_dewpoint(); + _recalc_alt_pressure(); + _recalc_density(); } void @@ -369,6 +486,28 @@ FGEnvironment::_recalc_alt_temperature () } } +void +FGEnvironment::_recalc_sl_dewpoint () +{ + // 0.2degC/1000ft + // FIXME: this will work only for low + // elevations + dewpoint_sea_level_degc = dewpoint_degc + (elevation_ft * .0002); + if (dewpoint_sea_level_degc > temperature_sea_level_degc) + dewpoint_sea_level_degc = temperature_sea_level_degc; +} + +void +FGEnvironment::_recalc_alt_dewpoint () +{ + // 0.2degC/1000ft + // FIXME: this will work only for low + // elevations + dewpoint_degc = dewpoint_sea_level_degc + (elevation_ft * .0002); + if (dewpoint_degc > temperature_degc) + dewpoint_degc = temperature_degc; +} + void FGEnvironment::_recalc_sl_pressure () { @@ -384,18 +523,98 @@ FGEnvironment::_recalc_alt_pressure () } void -FGEnvironment::_recalc_sl_density () +FGEnvironment::_recalc_density () { - density_sea_level_slugft3 = - density_slugft3 / _density_slugft3_table->interpolate(elevation_ft); + double pressure_psf = pressure_inhg * 70.7487; + + // adjust for humidity + // calculations taken from USA Today (oops!) at + // http://www.usatoday.com/weather/basics/density-calculations.htm + double temperature_degk = temperature_degc + 273.15; + double pressure_mb = pressure_inhg * 33.86; + double vapor_pressure_mb = + 6.11 * pow(10.0, 7.5 * dewpoint_degc / (237.7 + dewpoint_degc)); + double virtual_temperature_degk = temperature_degk / (1 - (vapor_pressure_mb / pressure_mb) * (1.0 - 0.622)); + double virtual_temperature_degr = virtual_temperature_degk * 1.8; + + density_slugft3 = pressure_psf / (virtual_temperature_degr * 1718); } -void -FGEnvironment::_recalc_alt_density () + + +//////////////////////////////////////////////////////////////////////// +// Functions. +//////////////////////////////////////////////////////////////////////// + +static inline double +do_interp (double a, double b, double fraction) +{ + double retval = (a + ((b - a) * fraction)); + return retval; +} + +static inline double +do_interp_deg (double a, double b, double fraction) { - density_slugft3 = - density_sea_level_slugft3 * - _density_slugft3_table->interpolate(elevation_ft); + a = fmod(a, 360); + b = fmod(b, 360); + if (fabs(b-a) > 180) { + if (a < b) + a += 360; + else + b += 360; + } + return fmod(do_interp(a, b, fraction), 360); +} + +void +interpolate (const FGEnvironment * env1, const FGEnvironment * env2, + double fraction, FGEnvironment * result) +{ + result->set_visibility_m + (do_interp(env1->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(), + fraction)); + + result->set_dewpoint_degc + (do_interp(env1->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(), + fraction)); + + result->set_wind_from_heading_deg + (do_interp_deg(env1->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(), + fraction)); + + result->set_elevation_ft + (do_interp(env1->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(), + fraction)); + + result->set_turbulence_rate_hz + (do_interp(env1->get_turbulence_rate_hz(), + env2->get_turbulence_rate_hz(), + fraction)); } // end of environment.cxx