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// metarproperties.cxx -- Parse a METAR and write properties
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// Written by David Megginson, started May 2002.
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// Rewritten by Torsten Dreyer, August 2010
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// Copyright (C) 2002 David Megginson - david@megginson.com
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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#include "metarproperties.hxx"
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#include "fgmetar.hxx"
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#include "environment.hxx"
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#include "atmosphere.hxx"
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#include "metarairportfilter.hxx"
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#include <simgear/scene/sky/cloud.hxx>
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#include <simgear/structure/exception.hxx>
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#include <simgear/misc/strutils.hxx>
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#include <simgear/magvar/magvar.hxx>
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#include <simgear/timing/sg_time.hxx>
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#include <Main/fg_props.hxx>
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namespace Environment {
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static vector<string> coverage_string;
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* @brief Helper class to wrap SGMagVar functionality and cache the variation and dip for
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class MagneticVariation : public SGMagVar {
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MagneticVariation() : _lat(1), _lon(1), _alt(1) {
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recalc( 0.0, 0.0, 0.0 );
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* @brief get the magnetic variation for a specific position at the current time
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* @param lon the positions longitude in degrees
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* @param lat the positions latitude in degrees
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* @param alt the positions height above MSL (aka altitude) in feet
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* @return the magnetic variation in degrees
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double get_variation_deg( double lon, double lat, double alt );
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* @brief get the magnetic dip for a specific position at the current time
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* @param lon the positions longitude in degrees
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* @param lat the positions latitude in degrees
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* @param alt the positions height above MSL (aka altitude) in feet
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* @return the magnetic dip in degrees
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double get_dip_deg( double lon, double lat, double alt );
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void recalc( double lon, double lat, double alt );
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double _lat, _lon, _alt;
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inline void MagneticVariation::recalc( double lon, double lat, double alt )
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// calculation of magnetic variation is expensive. Cache the position
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// and perform this calculation only if it has changed
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if( _lon != lon || _lat != lat || _alt != alt ) {
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SG_LOG(SG_ALL, SG_DEBUG, "Recalculating magvar for lon=" << lon << ", lat=" << lat << ", alt=" << alt );
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lon *= SGD_DEGREES_TO_RADIANS;
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lat *= SGD_DEGREES_TO_RADIANS;
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alt *= SG_FEET_TO_METER;
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_time.update( lon, lat, 0, 0 );
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update( lon, lat, alt, _time.getJD() );
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inline double MagneticVariation::get_variation_deg( double lon, double lat, double alt )
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recalc( lon, lat, alt );
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return get_magvar() * SGD_RADIANS_TO_DEGREES;
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inline double MagneticVariation::get_dip_deg( double lon, double lat, double alt )
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recalc( lon, lat, alt );
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return get_magdip() * SGD_RADIANS_TO_DEGREES;
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MetarProperties::MetarProperties( SGPropertyNode_ptr rootNode ) :
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_metarValidNode( rootNode->getNode( "valid", true ) ),
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_station_elevation(0.0),
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_station_latitude(0.0),
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_station_longitude(0.0),
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_min_visibility(16000.0),
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_max_visibility(16000.0),
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_base_wind_range_from(0),
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_base_wind_range_to(0),
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_wind_from_north_fps(0.0),
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_wind_from_east_fps(0.0),
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_sea_level_temperature(0.0),
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_sea_level_dewpoint(0.0),
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_sea_level_pressure(29.92),
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_magneticVariation(new MagneticVariation())
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// Hack to avoid static initialization order problems on OSX
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if( coverage_string.size() == 0 ) {
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coverage_string.push_back(SGCloudLayer::SG_CLOUD_CLEAR_STRING);
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coverage_string.push_back(SGCloudLayer::SG_CLOUD_FEW_STRING);
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coverage_string.push_back(SGCloudLayer::SG_CLOUD_SCATTERED_STRING);
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coverage_string.push_back(SGCloudLayer::SG_CLOUD_BROKEN_STRING);
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coverage_string.push_back(SGCloudLayer::SG_CLOUD_OVERCAST_STRING);
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// don't tie metar-valid, so listeners get triggered
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_metarValidNode->setBoolValue( false );
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_tiedProperties.setRoot( _rootNode );
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_tiedProperties.Tie("data", this, &MetarProperties::get_metar, &MetarProperties::set_metar );
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_tiedProperties.Tie("station-id", this, &MetarProperties::get_station_id, &MetarProperties::set_station_id );
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_tiedProperties.Tie("station-elevation-ft", &_station_elevation );
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_tiedProperties.Tie("station-latitude-deg", &_station_latitude );
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_tiedProperties.Tie("station-longitude-deg", &_station_longitude );
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_tiedProperties.Tie("station-magnetic-variation-deg", this, &MetarProperties::get_magnetic_variation_deg );
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_tiedProperties.Tie("station-magnetic-dip-deg", this, &MetarProperties::get_magnetic_dip_deg );
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_tiedProperties.Tie("min-visibility-m", &_min_visibility );
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_tiedProperties.Tie("max-visibility-m", &_max_visibility );
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_tiedProperties.Tie("base-wind-range-from", &_base_wind_range_from );
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_tiedProperties.Tie("base-wind-range-to", &_base_wind_range_to );
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_tiedProperties.Tie("base-wind-speed-kt", this, &MetarProperties::get_wind_speed, &MetarProperties::set_wind_speed );
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_tiedProperties.Tie("base-wind-dir-deg", this, &MetarProperties::get_base_wind_dir, &MetarProperties::set_base_wind_dir );
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_tiedProperties.Tie("base-wind-from-north-fps", this, &MetarProperties::get_wind_from_north_fps, &MetarProperties::set_wind_from_north_fps );
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_tiedProperties.Tie("base-wind-from-east-fps",this, &MetarProperties::get_wind_from_east_fps, &MetarProperties::set_wind_from_east_fps );
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_tiedProperties.Tie("gust-wind-speed-kt", &_gusts );
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_tiedProperties.Tie("temperature-degc", &_temperature );
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_tiedProperties.Tie("dewpoint-degc", &_dewpoint );
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_tiedProperties.Tie("rel-humidity-norm", &_humidity );
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_tiedProperties.Tie("pressure-inhg", &_pressure );
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_tiedProperties.Tie("temperature-sea-level-degc", &_sea_level_temperature );
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_tiedProperties.Tie("dewpoint-sea-level-degc", &_sea_level_dewpoint );
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_tiedProperties.Tie("pressure-sea-level-inhg", &_sea_level_pressure );
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_tiedProperties.Tie("rain-norm", &_rain );
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_tiedProperties.Tie("hail-norm", &_hail );
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_tiedProperties.Tie("snow-norm", &_snow);
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_tiedProperties.Tie("snow-cover", &_snow_cover );
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_tiedProperties.Tie("decoded", this, &MetarProperties::get_decoded );
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MetarProperties::~MetarProperties()
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delete _magneticVariation;
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static const double thickness_value[] = { 0, 65, 600, 750, 1000 };
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void MetarProperties::set_metar( const char * metar )
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SGSharedPtr<FGMetar> m;
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m = new FGMetar( _metar );
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catch( sg_io_exception ) {
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SG_LOG( SG_GENERAL, SG_WARN, "Can't parse metar: " << _metar );
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_metarValidNode->setBoolValue(false);
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const vector<string> weather = m->getWeather();
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for( vector<string>::const_iterator it = weather.begin(); it != weather.end(); it++ ) {
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if( false == _decoded.empty() ) _decoded.append(", ");
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_decoded.append(*it);
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_min_visibility = m->getMinVisibility().getVisibility_m();
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_max_visibility = m->getMaxVisibility().getVisibility_m();
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const SGMetarVisibility *dirvis = m->getDirVisibility();
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for ( int i = 0; i < 8; i++, dirvis++) {
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SGPropertyNode *vis = _rootNode->getChild("visibility", i, true);
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double v = dirvis->getVisibility_m();
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vis->setDoubleValue("min-m", v);
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vis->setDoubleValue("max-m", v);
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set_base_wind_dir(m->getWindDir());
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_base_wind_range_from = m->getWindRangeFrom();
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_base_wind_range_to = m->getWindRangeTo();
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set_wind_speed(m->getWindSpeed_kt());
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_gusts = m->getGustSpeed_kt();
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_temperature = m->getTemperature_C();
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_dewpoint = m->getDewpoint_C();
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_humidity = m->getRelHumidity();
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_pressure = m->getPressure_inHg();
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// 1. check the id given in the metar
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FGAirport* a = FGAirport::findByIdent(m->getId());
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// 2. if unknown, find closest airport with metar to current position
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SGGeod pos = SGGeod::fromDeg(
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fgGetDouble( "/position/longitude-deg", 0.0 ),
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fgGetDouble( "/position/latitude-deg", 0.0 ) );
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a = FGAirport::findClosest(pos, 10000.0, MetarAirportFilter::instance() );
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// 3. otherwise use ground elevation
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_station_elevation = a->getElevation();
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const SGGeod & towerPosition = a->getTowerLocation();
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_station_latitude = towerPosition.getLatitudeDeg();
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_station_longitude = towerPosition.getLongitudeDeg();
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_station_id = a->ident();
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_station_elevation = fgGetDouble("/position/ground-elev-m", 0.0 ) * SG_METER_TO_FEET;
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_station_latitude = fgGetDouble( "/position/latitude-deg", 0.0 );
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_station_longitude = fgGetDouble( "/position/longitude-deg", 0.0 );
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_station_id = "XXXX";
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{ // calculate sea level temperature, dewpoint and pressure
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FGEnvironment dummy; // instantiate a dummy so we can leech a method
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dummy.set_elevation_ft( _station_elevation );
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dummy.set_temperature_degc( _temperature );
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dummy.set_dewpoint_degc( _dewpoint );
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_sea_level_temperature = dummy.get_temperature_sea_level_degc();
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_sea_level_dewpoint = dummy.get_dewpoint_sea_level_degc();
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double elevation_m = _station_elevation * SG_FEET_TO_METER;
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double fieldPressure = FGAtmo::fieldPressure( elevation_m, _pressure * atmodel::inHg );
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_sea_level_pressure = P_layer(0, elevation_m, fieldPressure, _temperature + atmodel::freezing, atmodel::ISA::lam0) / atmodel::inHg;
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for( unsigned i = 0; i < 3; i++ ) {
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SGPropertyNode_ptr n = _rootNode->getChild("weather", i, true );
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vector<struct SGMetar::Weather> weather = m->getWeather2();
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struct SGMetar::Weather * w = i < weather.size() ? &weather[i] : NULL;
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n->getNode("intensity",true)->setIntValue( w != NULL ? w->intensity : 0 );
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n->getNode("vincinity",true)->setBoolValue( w != NULL ? w->vincinity : false );
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for( unsigned j = 0; j < 3; j++ ) {
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const string & phenomenon = w != NULL && j < w->phenomena.size() ? w->phenomena[j].c_str() : "";
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n->getChild( "phenomenon", j, true )->setStringValue( phenomenon );
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const string & description = w != NULL && j < w->descriptions.size() ? w->descriptions[j].c_str() : "";
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n->getChild( "description", j, true )->setStringValue( description );
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// need to know later,
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// if its fog(FG) (might be shallow(MI) or patches(BC)) or haze (HZ) or mist(BR)
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if( phenomenon == "FG" ) isFG = true;
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if( phenomenon == "HZ" ) isHZ = true;
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if( phenomenon == "BR" ) isBR = true;
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if( description == "MI" ) isMI = true;
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if( description == "BC" ) isBC = true;
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static const char * LAYER = "layer";
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SGPropertyNode_ptr cloudsNode = _rootNode->getNode("clouds", true );
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const vector<SGMetarCloud> & metarClouds = m->getClouds();
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unsigned layerOffset = 0; // Oh, this is ugly!
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// fog/mist/haze cloud layer does not work with 3d clouds yet :-(
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bool setGroundCloudLayer = _rootNode->getBoolValue("set-ground-cloud-layer", false ) &&
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false == (fgGetBool("/sim/rendering/shader-effects", false ) &&
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fgGetBool("/sim/rendering/clouds3d-enable", false ) );
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if( setGroundCloudLayer ) {
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// create a cloud layer #0 starting at the ground if its fog, mist or haze
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// make sure layer actually starts at ground and set it's bottom at a constant
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// value below the station's elevation
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const double LAYER_BOTTOM_STATION_OFFSET =
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fgGetDouble( "/environment/params/fog-mist-haze-layer/offset-from-station-elevation-ft", -200 );
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SGMetarCloud::Coverage coverage = SGMetarCloud::COVERAGE_NIL;
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double thickness = 0;
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coverage = SGMetarCloud::getCoverage( isBC ?
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fgGetString( "/environment/params/fog-mist-haze-layer/fog-bc-2dlayer-coverage", SGMetarCloud::COVERAGE_SCATTERED_STRING ) :
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fgGetString( "/environment/params/fog-mist-haze-layer/fog-2dlayer-coverage", SGMetarCloud::COVERAGE_BROKEN_STRING )
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fgGetDouble("/environment/params/fog-mist-haze-layer/fog-shallow-thickness-ft",30) - LAYER_BOTTOM_STATION_OFFSET : // shallow fog, 10m/30ft
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fgGetDouble("/environment/params/fog-mist-haze-layer/fog-thickness-ft",500) - LAYER_BOTTOM_STATION_OFFSET; // fog, 150m/500ft
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alpha = fgGetDouble("/environment/params/fog-mist-haze-layer/fog-2dlayer-alpha", 1.0);
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} else if( isBR ) { // mist
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coverage = SGMetarCloud::getCoverage(fgGetString("/environment/params/fog-mist-haze-layer/mist-2dlayer-coverage", SGMetarCloud::COVERAGE_OVERCAST_STRING));
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thickness = fgGetDouble("/environment/params/fog-mist-haze-layer/mist-thickness-ft",2000) - LAYER_BOTTOM_STATION_OFFSET;
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alpha = fgGetDouble("/environment/params/fog-mist-haze-layer/mist-2dlayer-alpha",0.8);
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} else if( isHZ ) { // haze
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coverage = SGMetarCloud::getCoverage(fgGetString("/environment/params/fog-mist-haze-layer/mist-2dlayer-coverage", SGMetarCloud::COVERAGE_OVERCAST_STRING));
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thickness = fgGetDouble("/environment/params/fog-mist-haze-layer/haze-thickness-ft",2000) - LAYER_BOTTOM_STATION_OFFSET;
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alpha = fgGetDouble("/environment/params/fog-mist-haze-layer/haze-2dlayer-alpha",0.6);
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if( coverage != SGMetarCloud::COVERAGE_NIL ) {
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// if there is a layer above the fog, limit the top to one foot below that layer's bottom
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if( metarClouds.size() > 0 && metarClouds[0].getCoverage() != SGMetarCloud::COVERAGE_CLEAR )
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thickness = metarClouds[0].getAltitude_ft() - LAYER_BOTTOM_STATION_OFFSET - 1;
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SGPropertyNode_ptr layerNode = cloudsNode->getChild(LAYER, 0, true );
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layerNode->setDoubleValue( "coverage-type", SGCloudLayer::getCoverageType(coverage_string[coverage]) );
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layerNode->setStringValue( "coverage", coverage_string[coverage] );
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layerNode->setDoubleValue( "elevation-ft", _station_elevation + LAYER_BOTTOM_STATION_OFFSET );
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layerNode->setDoubleValue( "thickness-ft", thickness );
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layerNode->setDoubleValue( "visibility-m", _min_visibility );
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layerNode->setDoubleValue( "alpha", alpha );
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_min_visibility = _max_visibility =
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fgGetDouble("/environment/params/fog-mist-haze-layer/visibility-above-layer-m",20000.0); // assume good visibility above the fog
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layerOffset = 1; // shudder
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for( unsigned i = 0; i < 5-layerOffset; i++ ) {
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SGPropertyNode_ptr layerNode = cloudsNode->getChild(LAYER, i+layerOffset, true );
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SGMetarCloud::Coverage coverage = i < metarClouds.size() ? metarClouds[i].getCoverage() : SGMetarCloud::COVERAGE_CLEAR;
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i >= metarClouds.size() || coverage == SGMetarCloud::COVERAGE_CLEAR ?
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metarClouds[i].getAltitude_ft() + _station_elevation;
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layerNode->setDoubleValue( "alpha", 1.0 );
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layerNode->setStringValue( "coverage", coverage_string[coverage] );
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layerNode->setDoubleValue( "coverage-type", SGCloudLayer::getCoverageType(coverage_string[coverage]) );
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layerNode->setDoubleValue( "elevation-ft", elevation );
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layerNode->setDoubleValue( "thickness-ft", thickness_value[coverage]);
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layerNode->setDoubleValue( "span-m", 40000 );
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layerNode->setDoubleValue( "visibility-m", 50.0 );
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_rain = m->getRain();
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_hail = m->getHail();
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_snow = m->getSnow();
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_snow_cover = m->getSnowCover();
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_metarValidNode->setBoolValue(true);
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void MetarProperties::setStationId( const std::string & value )
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set_station_id(simgear::strutils::strip(value).c_str());
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double MetarProperties::get_magnetic_variation_deg() const
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return _magneticVariation->get_variation_deg( _station_longitude, _station_latitude, _station_elevation );
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double MetarProperties::get_magnetic_dip_deg() const
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return _magneticVariation->get_dip_deg( _station_longitude, _station_latitude, _station_elevation );
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static inline void calc_wind_hs( double north_fps, double east_fps, int & heading_deg, double & speed_kt )
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speed_kt = sqrt((north_fps)*(north_fps)+(east_fps)*(east_fps)) * 3600.0 / (SG_NM_TO_METER * SG_METER_TO_FEET);
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heading_deg = SGMiscd::roundToInt(
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SGMiscd::normalizeAngle2( atan2( east_fps, north_fps ) ) * SGD_RADIANS_TO_DEGREES );
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void MetarProperties::set_wind_from_north_fps( double value )
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_wind_from_north_fps = value;
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calc_wind_hs( _wind_from_north_fps, _wind_from_east_fps, _base_wind_dir, _wind_speed );
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void MetarProperties::set_wind_from_east_fps( double value )
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_wind_from_east_fps = value;
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calc_wind_hs( _wind_from_north_fps, _wind_from_east_fps, _base_wind_dir, _wind_speed );
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static inline void calc_wind_ne( double heading_deg, double speed_kt, double & north_fps, double & east_fps )
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double speed_fps = speed_kt * SG_NM_TO_METER * SG_METER_TO_FEET / 3600.0;
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north_fps = speed_fps * cos(heading_deg * SGD_DEGREES_TO_RADIANS);
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east_fps = speed_fps * sin(heading_deg * SGD_DEGREES_TO_RADIANS);
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void MetarProperties::set_base_wind_dir( double value )
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_base_wind_dir = value;
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calc_wind_ne( (double)_base_wind_dir, _wind_speed, _wind_from_north_fps, _wind_from_east_fps );
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void MetarProperties::set_wind_speed( double value )
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calc_wind_ne( (double)_base_wind_dir, _wind_speed, _wind_from_north_fps, _wind_from_east_fps );
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} // namespace Environment