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/fg_geodesy.hxx>
30 #include <FDM/LaRCsim/ls_interface.h>
31 #include <Main/options.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;
50 int FGInterface::init( double dt ) {
51 cout << "dummy init() ... SHOULDN'T BE CALLED!" << endl;
55 int FGInterface::update( int multi_loop ) {
56 cout << "dummy update() ... SHOULDN'T BE CALLED!" << endl;
60 FGInterface::~FGInterface() {
63 // Extrapolate fdm based on time_offset (in usec)
64 void FGInterface::extrapolate( int time_offset ) {
65 double dt = time_offset / 1000000.0;
67 // -dw- metrowerks complains about ambiguous access, not critical
70 cout << "extrapolating FDM by dt = " << dt << endl;
73 double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
74 double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
76 double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
77 double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
79 double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
80 double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
82 geodetic_position_v[0] = lat;
83 geocentric_position_v[0] = lat_geoc;
85 geodetic_position_v[1] = lon;
86 geocentric_position_v[1] = lon_geoc;
88 geodetic_position_v[2] = alt;
89 geocentric_position_v[2] = radius;
93 // Set the altitude (force)
94 void fgFDMForceAltitude(int model, double alt_meters) {
95 double sea_level_radius_meters;
98 // Set the FG variables first
99 fgGeodToGeoc( base_fdm_state.get_Latitude(), alt_meters,
100 &sea_level_radius_meters, &lat_geoc);
102 base_fdm_state.set_Altitude( alt_meters * METER_TO_FEET );
103 base_fdm_state.set_Radius_to_vehicle( base_fdm_state.get_Altitude() +
104 (sea_level_radius_meters *
107 // additional work needed for some flight models
108 if ( model == FGInterface::FG_LARCSIM ) {
109 ls_ForceAltitude( base_fdm_state.get_Altitude() );
114 // Set the local ground elevation
115 void fgFDMSetGroundElevation(int model, double ground_meters) {
116 base_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );
117 cur_fdm_state->set_Runway_altitude( ground_meters * METER_TO_FEET );