1 // flight.c -- a general interface to the various flight models
3 // Written by Curtis Olson, started May 1997.
5 // Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 #include <simgear/constants.h>
27 #include <simgear/debug/logstream.hxx>
28 #include <simgear/math/sg_geodesy.hxx>
30 #include <FDM/LaRCsim/ls_interface.h>
31 #include <Main/globals.hxx>
32 #include <Time/timestamp.hxx>
34 #include "External.hxx"
37 #include "LaRCsim.hxx"
41 // base_fdm_state is the internal state that is updated in integer
42 // multiples of "dt". This leads to "jitter" with respect to the real
43 // world time, so we introduce cur_fdm_state which is extrapolated by
44 // the difference between sim time and real world time
46 FGInterface *cur_fdm_state;
47 FGInterface base_fdm_state;
51 FGInterface::FGInterface(void) {
52 mass=i_xx=i_yy=i_zz=i_xz=0;
54 v_rel_wind=v_true_kts=v_rel_ground=v_inertial=0;
55 v_ground_speed=v_equiv=v_equiv_kts=0;
56 v_calibrated=v_calibrated_kts=0;
59 alpha=beta=alpha_dot=beta_dot=0;
60 cos_alpha=sin_alpha=cos_beta=sin_beta=0;
61 cos_phi=sin_phi=cos_theta=sin_theta=cos_psi=sin_psi=0;
62 gamma_vert_rad=gamma_horiz_rad=0;
63 sigma=density=v_sound=mach_number=0;
64 static_pressure=total_pressure=impact_pressure=0;
66 static_temperature=total_temperature=0;
67 sea_level_radius=earth_position_angle=0;
68 runway_altitude=runway_latitude=runway_longitude=0;
72 sin_lat_geocentric=cos_lat_geocentric=0;
73 sin_longitude=cos_longitude=0;
78 FGInterface::~FGInterface() {
82 bool FGInterface::init( double dt ) {
83 cout << "dummy init() ... SHOULDN'T BE CALLED!" << endl;
88 bool FGInterface::update( int multi_loop ) {
89 cout << "dummy update() ... SHOULDN'T BE CALLED!" << endl;
94 // Extrapolate fdm based on time_offset (in usec)
95 void FGInterface::extrapolate( int time_offset ) {
96 double dt = time_offset / 1000000.0;
98 // -dw- metrowerks complains about ambiguous access, not critical
101 cout << "extrapolating FDM by dt = " << dt << endl;
104 double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
105 double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
107 double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
108 double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
110 double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
111 double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
113 geodetic_position_v[0] = lat;
114 geocentric_position_v[0] = lat_geoc;
116 geodetic_position_v[1] = lon;
117 geocentric_position_v[1] = lon_geoc;
119 geodetic_position_v[2] = alt;
120 geocentric_position_v[2] = radius;
124 // Set the altitude (force)
125 void fgFDMForceAltitude(int model, double alt_meters) {
126 double sea_level_radius_meters;
129 // Set the FG variables first
130 sgGeodToGeoc( base_fdm_state.get_Latitude(), alt_meters,
131 &sea_level_radius_meters, &lat_geoc);
133 base_fdm_state.set_Altitude( alt_meters * METER_TO_FEET );
134 base_fdm_state.set_Radius_to_vehicle( base_fdm_state.get_Altitude() +
135 (sea_level_radius_meters *
138 // additional work needed for some flight models
139 if ( model == FGInterface::FG_LARCSIM ) {
140 ls_ForceAltitude( base_fdm_state.get_Altitude() );
145 // Set the local ground elevation
146 void fgFDMSetGroundElevation(int model, double ground_meters) {
147 base_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );
148 cur_fdm_state->set_Runway_altitude( ground_meters * METER_TO_FEET );