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 <Debug/logstream.hxx>
27 #include <FDM/External/external.hxx>
28 #include <FDM/LaRCsim/ls_interface.h>
29 #include <Include/fg_constants.h>
30 #include <Math/fg_geodesy.hxx>
31 #include <Time/timestamp.hxx>
35 #include "LaRCsim.hxx"
38 // base_fdm_state is the internal state that is updated in integer
39 // multiples of "dt". This leads to "jitter" with respect to the real
40 // world time, so we introduce cur_fdm_state which is extrapolated by
41 // the difference between sim time and real world time
43 FGInterface cur_fdm_state;
44 FGInterface base_fdm_state;
47 // Extrapolate fdm based on time_offset (in usec)
48 void FGInterface::extrapolate( int time_offset ) {
49 double dt = time_offset / 1000000.0;
50 cout << "extrapolating FDM by dt = " << dt << endl;
52 double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
53 double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
55 double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
56 double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
58 double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
59 double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
61 geodetic_position_v[0] = lat;
62 geocentric_position_v[0] = lat_geoc;
64 geodetic_position_v[1] = lon;
65 geocentric_position_v[1] = lon_geoc;
67 geodetic_position_v[2] = alt;
68 geocentric_position_v[2] = radius;
72 // Initialize the flight model parameters
73 int fgFDMInit(int model, FGInterface& f, double dt) {
74 double save_alt = 0.0;
76 FG_LOG( FG_FLIGHT ,FG_INFO, "Initializing flight model" );
80 if ( model == FGInterface::FG_SLEW ) {
82 } else if ( model == FGInterface::FG_JSBSIM ) {
84 fgJSBsim_2_FGInterface(base_fdm_state);
85 } else if ( model == FGInterface::FG_LARCSIM ) {
86 // lets try to avoid really screwing up the LaRCsim model
87 if ( base_fdm_state.get_Altitude() < -9000.0 ) {
88 save_alt = base_fdm_state.get_Altitude();
89 base_fdm_state.set_Altitude( 0.0 );
92 // translate FG to LaRCsim structure
93 FGInterface_2_LaRCsim(base_fdm_state);
98 FG_LOG( FG_FLIGHT, FG_INFO, "FG pos = " <<
99 base_fdm_state.get_Latitude() );
101 // translate LaRCsim back to FG structure
102 fgLaRCsim_2_FGInterface(base_fdm_state);
104 // but lets restore our original bogus altitude when we are done
105 if ( save_alt < -9000.0 ) {
106 base_fdm_state.set_Altitude( save_alt );
108 } else if ( model == FGInterface::FG_EXTERNAL ) {
109 fgExternalInit(base_fdm_state);
111 FG_LOG( FG_FLIGHT, FG_WARN,
112 "Unimplemented flight model == " << model );
115 // set valid time for this record
116 base_fdm_state.stamp_time();
124 // Run multiloop iterations of the flight model
125 int fgFDMUpdate(int model, FGInterface& f, int multiloop, int time_offset) {
126 double time_step, start_elev, end_elev;
128 // printf("Altitude = %.2f\n", FG_Altitude * 0.3048);
130 // set valid time for this record
131 base_fdm_state.stamp_time();
133 time_step = (1.0 / DEFAULT_MODEL_HZ) * multiloop;
134 start_elev = base_fdm_state.get_Altitude();
136 if ( model == FGInterface::FG_SLEW ) {
137 // fgSlewUpdate(f, multiloop);
138 } else if ( model == FGInterface::FG_JSBSIM ) {
139 fgJSBsimUpdate(base_fdm_state, multiloop);
141 } else if ( model == FGInterface::FG_LARCSIM ) {
142 fgLaRCsimUpdate(base_fdm_state, multiloop);
143 // extrapolate position based on actual time
144 // f = extrapolate_fdm( base_fdm_state, time_offset );
146 } else if ( model == FGInterface::FG_EXTERNAL ) {
147 // fgExternalUpdate(f, multiloop);
151 f.extrapolate( current - base_fdm_state.get_time_stamp() );
153 FG_LOG( FG_FLIGHT, FG_WARN,
154 "Unimplemented flight model == " << model );
157 end_elev = base_fdm_state.get_Altitude();
159 if ( time_step > 0.0 ) {
161 base_fdm_state.set_Climb_Rate( (end_elev - start_elev) / time_step );
168 // Set the altitude (force)
169 void fgFDMForceAltitude(int model, double alt_meters) {
170 double sea_level_radius_meters;
173 // Set the FG variables first
174 fgGeodToGeoc( base_fdm_state.get_Latitude(), alt_meters,
175 &sea_level_radius_meters, &lat_geoc);
177 base_fdm_state.set_Altitude( alt_meters * METER_TO_FEET );
178 base_fdm_state.set_Radius_to_vehicle( base_fdm_state.get_Altitude() +
179 (sea_level_radius_meters *
182 // additional work needed for some flight models
183 if ( model == FGInterface::FG_LARCSIM ) {
184 ls_ForceAltitude( base_fdm_state.get_Altitude() );
189 // Set the local ground elevation
190 void fgFDMSetGroundElevation(int model, double ground_meters) {
191 base_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );
192 cur_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );