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/LaRCsim/ls_interface.h>
28 #include <Include/fg_constants.h>
29 #include <Main/options.hxx>
30 #include <Math/fg_geodesy.hxx>
31 #include <Time/timestamp.hxx>
33 #include "External.hxx"
36 #include "LaRCsim.hxx"
40 // base_fdm_state is the internal state that is updated in integer
41 // multiples of "dt". This leads to "jitter" with respect to the real
42 // world time, so we introduce cur_fdm_state which is extrapolated by
43 // the difference between sim time and real world time
45 FGInterface * cur_fdm_state;
46 FGInterface base_fdm_state;
49 int FGInterface::init( double dt ) {
50 cout << "dummy init() ... SHOULDN'T BE CALLED!" << endl;
54 int FGInterface::update( int multi_loop ) {
55 cout << "dummy update() ... SHOULDN'T BE CALLED!" << endl;
59 FGInterface::~FGInterface() {
62 // Extrapolate fdm based on time_offset (in usec)
63 void FGInterface::extrapolate( int time_offset ) {
64 double dt = time_offset / 1000000.0;
66 // -dw- metrowerks complains about ambiguous access, not critical
69 cout << "extrapolating FDM by dt = " << dt << endl;
72 double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
73 double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
75 double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
76 double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
78 double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
79 double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
81 geodetic_position_v[0] = lat;
82 geocentric_position_v[0] = lat_geoc;
84 geodetic_position_v[1] = lon;
85 geocentric_position_v[1] = lon_geoc;
87 geodetic_position_v[2] = alt;
88 geocentric_position_v[2] = radius;
92 // Set the altitude (force)
93 void fgFDMForceAltitude(int model, double alt_meters) {
94 double sea_level_radius_meters;
97 // Set the FG variables first
98 fgGeodToGeoc( base_fdm_state.get_Latitude(), alt_meters,
99 &sea_level_radius_meters, &lat_geoc);
101 base_fdm_state.set_Altitude( alt_meters * METER_TO_FEET );
102 base_fdm_state.set_Radius_to_vehicle( base_fdm_state.get_Altitude() +
103 (sea_level_radius_meters *
106 // additional work needed for some flight models
107 if ( model == FGInterface::FG_LARCSIM ) {
108 ls_ForceAltitude( base_fdm_state.get_Altitude() );
113 // Set the local ground elevation
114 void fgFDMSetGroundElevation(int model, double ground_meters) {
115 base_fdm_state.set_Runway_altitude( ground_meters * METER_TO_FEET );
116 cur_fdm_state->set_Runway_altitude( ground_meters * METER_TO_FEET );