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flightgear/src/FDM/flight.cxx

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C++

// flight.c -- a general interface to the various flight models
//
// Written by Curtis Olson, started May 1997.
//
// Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// 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.
//
// $Id$
#include <stdio.h>
#include <simgear/constants.h>
#include <simgear/debug/logstream.hxx>
#include <simgear/math/fg_geodesy.hxx>
#include <FDM/LaRCsim/ls_interface.h>
#include <Main/options.hxx>
#include <Time/timestamp.hxx>
#include "External.hxx"
#include "flight.hxx"
#include "JSBSim.hxx"
#include "LaRCsim.hxx"
#include "Balloon.h"
// base_fdm_state is the internal state that is updated in integer
// multiples of "dt". This leads to "jitter" with respect to the real
// world time, so we introduce cur_fdm_state which is extrapolated by
// the difference between sim time and real world time
FGInterface *cur_fdm_state;
FGInterface base_fdm_state;
// Constructor
FGInterface::FGInterface(void) {
mass=i_xx=i_yy=i_zz=i_xz=0;
nlf=0;
v_rel_wind=v_true_kts=v_rel_ground=v_inertial=0;
v_ground_speed=v_equiv=v_equiv_kts=0;
v_calibrated=v_calibrated_kts=0;
gravity=0;
centrifugal_relief=0;
alpha=beta=alpha_dot=beta_dot=0;
cos_alpha=sin_alpha=cos_beta=sin_beta=0;
cos_phi=sin_phi=cos_theta=sin_theta=cos_psi=sin_psi=0;
gamma_vert_rad=gamma_horiz_rad=0;
sigma=density=v_sound=mach_number=0;
static_pressure=total_pressure=impact_pressure=0;
dynamic_pressure=0;
static_temperature=total_temperature=0;
sea_level_radius=earth_position_angle=0;
runway_altitude=runway_latitude=runway_longitude=0;
runway_heading=0;
radius_to_rwy=0;
climb_rate=0;
sin_lat_geocentric=cos_lat_geocentric=0;
sin_longitude=cos_longitude=0;
}
// Destructor
FGInterface::~FGInterface() {
}
int FGInterface::init( double dt ) {
cout << "dummy init() ... SHOULDN'T BE CALLED!" << endl;
return 0;
}
int FGInterface::update( int multi_loop ) {
cout << "dummy update() ... SHOULDN'T BE CALLED!" << endl;
return 0;
}
// Extrapolate fdm based on time_offset (in usec)
void FGInterface::extrapolate( int time_offset ) {
double dt = time_offset / 1000000.0;
// -dw- metrowerks complains about ambiguous access, not critical
// to keep this ;)
#ifndef __MWERKS__
cout << "extrapolating FDM by dt = " << dt << endl;
#endif
double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
geodetic_position_v[0] = lat;
geocentric_position_v[0] = lat_geoc;
geodetic_position_v[1] = lon;
geocentric_position_v[1] = lon_geoc;
geodetic_position_v[2] = alt;
geocentric_position_v[2] = radius;
}
// Set the altitude (force)
void fgFDMForceAltitude(int model, double alt_meters) {
double sea_level_radius_meters;
double lat_geoc;
// Set the FG variables first
fgGeodToGeoc( base_fdm_state.get_Latitude(), alt_meters,
&sea_level_radius_meters, &lat_geoc);
base_fdm_state.set_Altitude( alt_meters * METER_TO_FEET );
base_fdm_state.set_Radius_to_vehicle( base_fdm_state.get_Altitude() +
(sea_level_radius_meters *
METER_TO_FEET) );
// additional work needed for some flight models
if ( model == FGInterface::FG_LARCSIM ) {
ls_ForceAltitude( base_fdm_state.get_Altitude() );
}
}
// Set the local ground elevation
void fgFDMSetGroundElevation(int model, double ground_meters) {
base_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );
cur_fdm_state->set_Runway_altitude( ground_meters * METER_TO_FEET );
}