src/FDM/flight.cxx

   1 // flight.cxx -- a general interface to the various flight models
   2 //
   3 // Written by Curtis Olson, started May 1997.
   4 //
   5 // Copyright (C) 1997  Curtis L. Olson  - http://www.flightgear.org/~curt
   6 //
   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.
  11 //
  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.
  16 //
  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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  20 //
  21 // $Id$
  22
  23 #ifdef HAVE_CONFIG_H
  24 #  include "config.h"
  25 #endif
  26
  27 #include <stdio.h>
  28
  29 #include <plib/sg.h>
  30
  31 #include <simgear/constants.h>
  32 #include <simgear/debug/logstream.hxx>
  33 #include <simgear/math/sg_geodesy.hxx>
  34 #include <simgear/scene/model/placement.hxx>
  35 #include <simgear/scene/material/mat.hxx>
  36 #include <simgear/timing/timestamp.hxx>
  37
  38 #include <Scenery/scenery.hxx>
  39 #include <Main/globals.hxx>
  40 #include <Main/fg_props.hxx>
  41 #include <FDM/groundcache.hxx>
  42
  43 #include "flight.hxx"
  44
  45
  46 // base_fdm_state is the internal state that is updated in integer
  47 // multiples of "dt".  This leads to "jitter" with respect to the real
  48 // world time, so we introduce cur_fdm_state which is extrapolated by
  49 // the difference between sim time and real world time
  50
  51 FGInterface *cur_fdm_state = 0;
  52 FGInterface base_fdm_state;
  53
  54 inline void init_vec(FG_VECTOR_3 vec) {
  55     vec[0] = 0.0; vec[1] = 0.0; vec[2] = 0.0;
  56 }
  57
  58 // Constructor
  59 FGInterface::FGInterface()
  60   : remainder(0)
  61 {
  62     _setup();
  63 }
  64
  65 FGInterface::FGInterface( double dt )
  66   : remainder(0)
  67 {
  68     _setup();
  69 }
  70
  71 // Destructor
  72 FGInterface::~FGInterface() {
  73     // unbind();                   // FIXME: should be called explicitly
  74 }
  75
  76
  77 int
  78 FGInterface::_calc_multiloop (double dt)
  79 {
  80   int hz = fgGetInt("/sim/model-hz");
  81   int speedup = fgGetInt("/sim/speed-up");
  82
  83   dt += remainder;
  84   remainder = 0;
  85   double ml = dt * hz;
  86   // Avoid roundoff problems by adding the roundoff itself.
  87   // ... ok, two times the roundoff to have enough room.
  88   int multiloop = int(floor(ml * (1.0 + 2.0*DBL_EPSILON)));
  89   remainder = (ml - multiloop) / hz;
  90   return (multiloop * speedup);
  91 }
  92
  93
  94 /**
  95  * Set default values for the state of the FDM.
  96  *
  97  * This method is invoked by the constructors.
  98  */
  99 void
 100 FGInterface::_setup ()
 101 {
 102     inited = false;
 103     bound = false;
 104
 105     init_vec( d_pilot_rp_body_v );
 106     init_vec( d_cg_rp_body_v );
 107     init_vec( f_body_total_v );
 108     init_vec( f_local_total_v );
 109     init_vec( f_aero_v );
 110     init_vec( f_engine_v );
 111     init_vec( f_gear_v );
 112     init_vec( m_total_rp_v );
 113     init_vec( m_total_cg_v );
 114     init_vec( m_aero_v );
 115     init_vec( m_engine_v );
 116     init_vec( m_gear_v );
 117     init_vec( v_dot_local_v );
 118     init_vec( v_dot_body_v );
 119     init_vec( a_cg_body_v );
 120     init_vec( a_pilot_body_v );
 121     init_vec( n_cg_body_v );
 122     init_vec( n_pilot_body_v );
 123     init_vec( omega_dot_body_v );
 124     init_vec( v_local_v );
 125     init_vec( v_local_rel_ground_v );
 126     init_vec( v_local_airmass_v );
 127     init_vec( v_local_rel_airmass_v );
 128     init_vec( v_local_gust_v );
 129     init_vec( v_wind_body_v );
 130     init_vec( omega_body_v );
 131     init_vec( omega_local_v );
 132     init_vec( omega_total_v );
 133     init_vec( euler_rates_v );
 134     init_vec( geocentric_rates_v );
 135     init_vec( geocentric_position_v );
 136     init_vec( geodetic_position_v );
 137     init_vec( euler_angles_v );
 138     init_vec( d_cg_rwy_local_v );
 139     init_vec( d_cg_rwy_rwy_v );
 140     init_vec( d_pilot_rwy_local_v );
 141     init_vec( d_pilot_rwy_rwy_v );
 142     init_vec( t_local_to_body_m[0] );
 143     init_vec( t_local_to_body_m[1] );
 144     init_vec( t_local_to_body_m[2] );
 145
 146     mass=i_xx=i_yy=i_zz=i_xz=0;
 147     nlf=0;
 148     v_rel_wind=v_true_kts=v_rel_ground=v_inertial=0;
 149     v_ground_speed=v_equiv=v_equiv_kts=0;
 150     v_calibrated=v_calibrated_kts=0;
 151     gravity=0;
 152     centrifugal_relief=0;
 153     alpha=beta=alpha_dot=beta_dot=0;
 154     cos_alpha=sin_alpha=cos_beta=sin_beta=0;
 155     cos_phi=sin_phi=cos_theta=sin_theta=cos_psi=sin_psi=0;
 156     gamma_vert_rad=gamma_horiz_rad=0;
 157     sigma=density=v_sound=mach_number=0;
 158     static_pressure=total_pressure=impact_pressure=0;
 159     dynamic_pressure=0;
 160     static_temperature=total_temperature=0;
 161     sea_level_radius=earth_position_angle=0;
 162     runway_altitude=runway_latitude=runway_longitude=0;
 163     runway_heading=0;
 164     radius_to_rwy=0;
 165     climb_rate=0;
 166     sin_lat_geocentric=cos_lat_geocentric=0;
 167     sin_latitude=cos_latitude=0;
 168     sin_longitude=cos_longitude=0;
 169     altitude_agl=0;
 170 }
 171
 172 void
 173 FGInterface::init () {}
 174
 175 /**
 176  * Initialize the state of the FDM.
 177  *
 178  * Subclasses of FGInterface may do their own, additional initialization,
 179  * but there is some that is common to all.  Normally, they should call
 180  * this before they begin their own init to make sure the basic structures
 181  * are set up properly.
 182  */
 183 void
 184 FGInterface::common_init ()
 185 {
 186     SG_LOG( SG_FLIGHT, SG_INFO, "Start common FDM init" );
 187
 188     set_inited( true );
 189
 190 //     stamp();
 191 //     set_remainder( 0 );
 192
 193     // Set initial position
 194     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing position..." );
 195     double lon = fgGetDouble("/sim/presets/longitude-deg")
 196       * SGD_DEGREES_TO_RADIANS;
 197     double lat = fgGetDouble("/sim/presets/latitude-deg")
 198       * SGD_DEGREES_TO_RADIANS;
 199     double alt_ft = fgGetDouble("/sim/presets/altitude-ft");
 200     double alt_m = alt_ft * SG_FEET_TO_METER;
 201     set_Longitude( lon );
 202     set_Latitude( lat );
 203     SG_LOG( SG_FLIGHT, SG_INFO, "Checking for lon = "
 204             << lon*SGD_RADIANS_TO_DEGREES << "deg, lat = "
 205             << lat*SGD_RADIANS_TO_DEGREES << "deg, alt = "
 206             << alt_ft << "ft");
 207
 208     double ground_elev_m = get_groundlevel_m(lat, lon, alt_m);
 209     double ground_elev_ft = ground_elev_m * SG_METER_TO_FEET;
 210     _set_Runway_altitude ( ground_elev_ft );
 211     if ( fgGetBool("/sim/presets/onground") || alt_ft < ground_elev_ft ) {
 212         fgSetDouble("/position/altitude-ft", ground_elev_ft + 0.1);
 213         set_Altitude( ground_elev_ft + 0.1);
 214     } else {
 215         set_Altitude( alt_ft );
 216     }
 217
 218     // Set ground elevation
 219     SG_LOG( SG_FLIGHT, SG_INFO,
 220             "...initializing ground elevation to " << ground_elev_ft
 221             << "ft..." );
 222
 223     // Set sea-level radius
 224     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing sea-level radius..." );
 225     SG_LOG( SG_FLIGHT, SG_INFO, " lat = "
 226             << fgGetDouble("/sim/presets/latitude-deg")
 227             << " alt = " << get_Altitude() );
 228     double sea_level_radius_meters;
 229     double lat_geoc;
 230     sgGeodToGeoc( fgGetDouble("/sim/presets/latitude-deg")
 231                     * SGD_DEGREES_TO_RADIANS,
 232                   get_Altitude() * SG_FEET_TO_METER,
 233                   &sea_level_radius_meters, &lat_geoc );
 234     _set_Sea_level_radius( sea_level_radius_meters * SG_METER_TO_FEET );
 235
 236     // Set initial velocities
 237     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing velocities..." );
 238     if ( !fgHasNode("/sim/presets/speed-set") ) {
 239         set_V_calibrated_kts(0.0);
 240     } else {
 241         const string speedset = fgGetString("/sim/presets/speed-set");
 242         if ( speedset == "knots" || speedset == "KNOTS" ) {
 243             set_V_calibrated_kts( fgGetDouble("/sim/presets/airspeed-kt") );
 244         } else if ( speedset == "mach" || speedset == "MACH" ) {
 245             set_Mach_number( fgGetDouble("/sim/presets/mach") );
 246         } else if ( speedset == "UVW" || speedset == "uvw" ) {
 247             set_Velocities_Wind_Body(
 248                                      fgGetDouble("/sim/presets/uBody-fps"),
 249                                      fgGetDouble("/sim/presets/vBody-fps"),
 250                                      fgGetDouble("/sim/presets/wBody-fps") );
 251         } else if ( speedset == "NED" || speedset == "ned" ) {
 252             set_Velocities_Local(
 253                                  fgGetDouble("/sim/presets/speed-north-fps"),
 254                                  fgGetDouble("/sim/presets/speed-east-fps"),
 255                                  fgGetDouble("/sim/presets/speed-down-fps") );
 256         } else {
 257             SG_LOG( SG_FLIGHT, SG_ALERT,
 258                     "Unrecognized value for /sim/presets/speed-set: "
 259                     << speedset);
 260             set_V_calibrated_kts( 0.0 );
 261         }
 262     }
 263
 264     // Set initial Euler angles
 265     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing Euler angles..." );
 266     set_Euler_Angles( fgGetDouble("/sim/presets/roll-deg")
 267                         * SGD_DEGREES_TO_RADIANS,
 268                       fgGetDouble("/sim/presets/pitch-deg")
 269                         * SGD_DEGREES_TO_RADIANS,
 270                       fgGetDouble("/sim/presets/heading-deg")
 271                         * SGD_DEGREES_TO_RADIANS );
 272
 273     SG_LOG( SG_FLIGHT, SG_INFO, "End common FDM init" );
 274 }
 275
 276
 277 /**
 278  * Bind getters and setters to properties.
 279  *
 280  * The bind() method will be invoked after init().  Note that unlike
 281  * the usual implementations of FGSubsystem::bind(), this method does
 282  * not automatically pick up existing values for the properties at
 283  * bind time; instead, all values are set explicitly in the init()
 284  * method.
 285  */
 286 void
 287 FGInterface::bind ()
 288 {
 289   bound = true;
 290
 291                                 // Time management (read-only)
 292 //   fgTie("/fdm/time/delta_t", this,
 293 //         &FGInterface::get_delta_t); // read-only
 294 //   fgTie("/fdm/time/elapsed", this,
 295 //         &FGInterface::get_elapsed); // read-only
 296 //   fgTie("/fdm/time/remainder", this,
 297 //         &FGInterface::get_remainder); // read-only
 298 //   fgTie("/fdm/time/multi_loop", this,
 299 //         &FGInterface::get_multi_loop); // read-only
 300
 301                         // Aircraft position
 302   fgTie("/position/latitude-deg", this,
 303         &FGInterface::get_Latitude_deg,
 304         &FGInterface::set_Latitude_deg,
 305         false);
 306   fgSetArchivable("/position/latitude-deg");
 307   fgTie("/position/longitude-deg", this,
 308         &FGInterface::get_Longitude_deg,
 309         &FGInterface::set_Longitude_deg,
 310         false);
 311   fgSetArchivable("/position/longitude-deg");
 312   fgTie("/position/altitude-ft", this,
 313         &FGInterface::get_Altitude,
 314         &FGInterface::set_Altitude,
 315         false);
 316   fgSetArchivable("/position/altitude-ft");
 317   fgTie("/position/altitude-agl-ft", this,
 318         &FGInterface::get_Altitude_AGL); // read-only
 319   fgSetArchivable("/position/ground-elev-ft");
 320   fgTie("/position/ground-elev-ft", this,
 321         &FGInterface::get_Runway_altitude); // read-only
 322   fgSetArchivable("/position/ground-elev-m");
 323   fgTie("/position/ground-elev-m", this,
 324         &FGInterface::get_Runway_altitude_m); // read-only
 325   fgTie("/environment/ground-elevation-m", this,
 326         &FGInterface::get_Runway_altitude_m); // read-only
 327   fgSetArchivable("/position/sea-level-radius-ft");
 328   fgTie("/position/sea-level-radius-ft", this,
 329         &FGInterface::get_Sea_level_radius); // read-only
 330
 331                                 // Orientation
 332   fgTie("/orientation/roll-deg", this,
 333         &FGInterface::get_Phi_deg,
 334         &FGInterface::set_Phi_deg);
 335   fgSetArchivable("/orientation/roll-deg");
 336   fgTie("/orientation/pitch-deg", this,
 337         &FGInterface::get_Theta_deg,
 338         &FGInterface::set_Theta_deg);
 339   fgSetArchivable("/orientation/pitch-deg");
 340   fgTie("/orientation/heading-deg", this,
 341         &FGInterface::get_Psi_deg,
 342         &FGInterface::set_Psi_deg);
 343   fgSetArchivable("/orientation/heading-deg");
 344
 345   // Body-axis "euler rates" (rotation speed, but in a funny
 346   // representation).
 347   fgTie("/orientation/roll-rate-degps", this,
 348         &FGInterface::get_Phi_dot_degps);
 349   fgTie("/orientation/pitch-rate-degps", this,
 350         &FGInterface::get_Theta_dot_degps);
 351   fgTie("/orientation/yaw-rate-degps", this,
 352         &FGInterface::get_Psi_dot_degps);
 353
 354                                 // Calibrated airspeed
 355   fgTie("/velocities/airspeed-kt", this,
 356         &FGInterface::get_V_calibrated_kts,
 357         &FGInterface::set_V_calibrated_kts,
 358         false);
 359
 360                                 // Mach number
 361   fgTie("/velocities/mach", this,
 362         &FGInterface::get_Mach_number,
 363         &FGInterface::set_Mach_number,
 364         false);
 365
 366                                 // Local velocities
 367 //   fgTie("/velocities/speed-north-fps", this,
 368 //      &FGInterface::get_V_north,
 369 //      &FGInterface::set_V_north);
 370 //   fgSetArchivable("/velocities/speed-north-fps");
 371 //   fgTie("/velocities/speed-east-fps", this,
 372 //      &FGInterface::get_V_east,
 373 //      &FGInterface::set_V_east);
 374 //   fgSetArchivable("/velocities/speed-east-fps");
 375 //   fgTie("/velocities/speed-down-fps", this,
 376 //      &FGInterface::get_V_down,
 377 //      &FGInterface::set_V_down);
 378 //   fgSetArchivable("/velocities/speed-down-fps");
 379                                 // FIXME: Temporarily read-only, until the
 380                                 // incompatibilities between JSBSim and
 381                                 // LaRCSim are fixed (LaRCSim adds the
 382                                 // earth's rotation to the east velocity).
 383   fgTie("/velocities/speed-north-fps", this,
 384         &FGInterface::get_V_north);
 385   fgTie("/velocities/speed-east-fps", this,
 386         &FGInterface::get_V_east);
 387   fgTie("/velocities/speed-down-fps", this,
 388         &FGInterface::get_V_down);
 389
 390                                 // Relative wind
 391                                 // FIXME: temporarily archivable, until
 392                                 // the NED problem is fixed.
 393   fgTie("/velocities/uBody-fps", this,
 394         &FGInterface::get_uBody,
 395         &FGInterface::set_uBody,
 396         false);
 397   fgSetArchivable("/velocities/uBody-fps");
 398   fgTie("/velocities/vBody-fps", this,
 399         &FGInterface::get_vBody,
 400         &FGInterface::set_vBody,
 401         false);
 402   fgSetArchivable("/velocities/vBody-fps");
 403   fgTie("/velocities/wBody-fps", this,
 404         &FGInterface::get_wBody,
 405         &FGInterface::set_wBody,
 406         false);
 407   fgSetArchivable("/velocities/wBody-fps");
 408
 409                                 // Climb and slip (read-only)
 410   fgTie("/velocities/vertical-speed-fps", this,
 411         &FGInterface::get_Climb_Rate,
 412   &FGInterface::set_Climb_Rate );
 413   fgTie("/velocities/glideslope", this,
 414   &FGInterface::get_Gamma_vert_rad,
 415   &FGInterface::set_Gamma_vert_rad );
 416   fgTie("/orientation/side-slip-rad", this,
 417         &FGInterface::get_Beta); // read-only
 418   fgTie("/orientation/side-slip-deg", this,
 419   &FGInterface::get_Beta_deg); // read-only
 420   fgTie("/orientation/alpha-deg", this,
 421   &FGInterface::get_Alpha_deg); // read-only
 422   fgTie("/accelerations/nlf", this,
 423   &FGInterface::get_Nlf); // read-only
 424
 425                                 // NED accelerations
 426   fgTie("/accelerations/ned/north-accel-fps_sec",
 427         this, &FGInterface::get_V_dot_north);
 428   fgTie("/accelerations/ned/east-accel-fps_sec",
 429         this, &FGInterface::get_V_dot_east);
 430   fgTie("/accelerations/ned/down-accel-fps_sec",
 431         this, &FGInterface::get_V_dot_down);
 432
 433                                 // Pilot accelerations
 434   fgTie("/accelerations/pilot/x-accel-fps_sec",
 435         this, &FGInterface::get_A_X_pilot);
 436   fgTie("/accelerations/pilot/y-accel-fps_sec",
 437         this, &FGInterface::get_A_Y_pilot);
 438   fgTie("/accelerations/pilot/z-accel-fps_sec",
 439         this, &FGInterface::get_A_Z_pilot);
 440
 441 }
 442
 443
 444 /**
 445  * Unbind any properties bound to this FDM.
 446  *
 447  * This method allows the FDM to release properties so that a new
 448  * FDM can bind them instead.
 449  */
 450 void
 451 FGInterface::unbind ()
 452 {
 453   bound = false;
 454
 455   // fgUntie("/fdm/time/delta_t");
 456   // fgUntie("/fdm/time/elapsed");
 457   // fgUntie("/fdm/time/remainder");
 458   // fgUntie("/fdm/time/multi_loop");
 459   fgUntie("/position/latitude-deg");
 460   fgUntie("/position/longitude-deg");
 461   fgUntie("/position/altitude-ft");
 462   fgUntie("/position/altitude-agl-ft");
 463   fgUntie("/position/ground-elev-ft");
 464   fgUntie("/position/ground-elev-m");
 465   fgUntie("/environment/ground-elevation-m");
 466   fgUntie("/position/sea-level-radius-ft");
 467   fgUntie("/orientation/roll-deg");
 468   fgUntie("/orientation/pitch-deg");
 469   fgUntie("/orientation/heading-deg");
 470   fgUntie("/orientation/roll-rate-degps");
 471   fgUntie("/orientation/pitch-rate-degps");
 472   fgUntie("/orientation/yaw-rate-degps");
 473   fgUntie("/orientation/side-slip-rad");
 474   fgUntie("/orientation/side-slip-deg");
 475   fgUntie("/orientation/alpha-deg");
 476   fgUntie("/velocities/airspeed-kt");
 477   fgUntie("/velocities/mach");
 478   fgUntie("/velocities/speed-north-fps");
 479   fgUntie("/velocities/speed-east-fps");
 480   fgUntie("/velocities/speed-down-fps");
 481   fgUntie("/velocities/uBody-fps");
 482   fgUntie("/velocities/vBody-fps");
 483   fgUntie("/velocities/wBody-fps");
 484   fgUntie("/velocities/vertical-speed-fps");
 485   fgUntie("/velocities/glideslope");
 486   fgUntie("/accelerations/nlf");
 487   fgUntie("/accelerations/pilot/x-accel-fps_sec");
 488   fgUntie("/accelerations/pilot/y-accel-fps_sec");
 489   fgUntie("/accelerations/pilot/z-accel-fps_sec");
 490   fgUntie("/accelerations/ned/north-accel-fps_sec");
 491   fgUntie("/accelerations/ned/east-accel-fps_sec");
 492   fgUntie("/accelerations/ned/down-accel-fps_sec");
 493 }
 494
 495 /**
 496  * Update the state of the FDM (i.e. run the equations of motion).
 497  */
 498 void
 499 FGInterface::update (double dt)
 500 {
 501     SG_LOG(SG_FLIGHT, SG_ALERT, "dummy update() ... SHOULDN'T BE CALLED!");
 502 }
 503
 504
 505 void FGInterface::_updateGeodeticPosition( double lat, double lon, double alt )
 506 {
 507     double lat_geoc, sl_radius;
 508
 509     // cout << "starting sea level rad = " << get_Sea_level_radius() << endl;
 510
 511     sgGeodToGeoc( lat, alt * SG_FEET_TO_METER, &sl_radius, &lat_geoc );
 512
 513     SG_LOG( SG_FLIGHT, SG_DEBUG, "lon = " << lon
 514             << " lat_geod = " << lat
 515             << " lat_geoc = " << lat_geoc
 516             << " alt = " << alt
 517             << " sl_radius = " << sl_radius * SG_METER_TO_FEET
 518             << " Equator = " << SG_EQUATORIAL_RADIUS_FT );
 519
 520     _set_Geocentric_Position( lat_geoc, lon,
 521                               sl_radius * SG_METER_TO_FEET + alt );
 522
 523     _set_Geodetic_Position( lat, lon, alt );
 524
 525     _set_Sea_level_radius( sl_radius * SG_METER_TO_FEET );
 526     _update_ground_elev_at_pos();
 527
 528     _set_sin_lat_geocentric( lat_geoc );
 529     _set_cos_lat_geocentric( lat_geoc );
 530
 531     _set_sin_cos_longitude( lon );
 532
 533     _set_sin_cos_latitude( lat );
 534 }
 535
 536
 537 void FGInterface::_updateGeocentricPosition( double lat_geoc, double lon,
 538                                              double alt )
 539 {
 540     double lat_geod, tmp_alt, sl_radius1, sl_radius2, tmp_lat_geoc;
 541
 542     // cout << "starting sea level rad = " << get_Sea_level_radius() << endl;
 543
 544     sgGeocToGeod( lat_geoc, ( get_Sea_level_radius() + alt ) * SG_FEET_TO_METER,
 545                   &lat_geod, &tmp_alt, &sl_radius1 );
 546     sgGeodToGeoc( lat_geod, alt * SG_FEET_TO_METER, &sl_radius2, &tmp_lat_geoc );
 547
 548     SG_LOG( SG_FLIGHT, SG_DEBUG, "lon = " << lon
 549             << " lat_geod = " << lat_geod
 550             << " lat_geoc = " << lat_geoc
 551             << " alt = " << alt
 552             << " tmp_alt = " << tmp_alt * SG_METER_TO_FEET
 553             << " sl_radius1 = " << sl_radius1 * SG_METER_TO_FEET
 554             << " sl_radius2 = " << sl_radius2 * SG_METER_TO_FEET
 555             << " Equator = " << SG_EQUATORIAL_RADIUS_FT );
 556
 557     _set_Geocentric_Position( lat_geoc, lon,
 558                               sl_radius2 * SG_METER_TO_FEET + alt );
 559
 560     _set_Geodetic_Position( lat_geod, lon, alt );
 561
 562     _set_Sea_level_radius( sl_radius2 * SG_METER_TO_FEET );
 563     _update_ground_elev_at_pos();
 564
 565     _set_sin_lat_geocentric( lat_geoc );
 566     _set_cos_lat_geocentric( lat_geoc );
 567
 568     _set_sin_cos_longitude( lon );
 569
 570     _set_sin_cos_latitude( lat_geod );
 571 }
 572
 573 void FGInterface::_update_ground_elev_at_pos( void ) {
 574     double lat = get_Latitude();
 575     double lon = get_Longitude();
 576     double alt_m = get_Altitude()*SG_FEET_TO_METER;
 577     double groundlevel_m = get_groundlevel_m(lat, lon, alt_m);
 578     _set_Runway_altitude( groundlevel_m * SG_METER_TO_FEET );
 579 }
 580
 581 // Extrapolate fdm based on time_offset (in usec)
 582 void FGInterface::extrapolate( int time_offset ) {
 583     double dt = time_offset / 1000000.0;
 584
 585     // -dw- metrowerks complains about ambiguous access, not critical
 586     // to keep this ;)
 587 #ifndef __MWERKS__
 588     SG_LOG(SG_FLIGHT, SG_INFO, "extrapolating FDM by dt = " << dt);
 589 #endif
 590
 591     double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
 592     double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
 593
 594     double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
 595     double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
 596
 597     double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
 598     double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
 599
 600     geodetic_position_v[0] = lat;
 601     geocentric_position_v[0] = lat_geoc;
 602
 603     geodetic_position_v[1] = lon;
 604     geocentric_position_v[1] = lon_geoc;
 605
 606     geodetic_position_v[2] = alt;
 607     geocentric_position_v[2] = radius;
 608 }
 609
 610 // Positions
 611 void FGInterface::set_Latitude(double lat) {
 612     geodetic_position_v[0] = lat;
 613 }
 614
 615 void FGInterface::set_Longitude(double lon) {
 616     geodetic_position_v[1] = lon;
 617 }
 618
 619 void FGInterface::set_Altitude(double alt) {
 620     geodetic_position_v[2] = alt;
 621 }
 622
 623 void FGInterface::set_AltitudeAGL(double altagl) {
 624     altitude_agl=altagl;
 625 }
 626
 627 // Velocities
 628 void FGInterface::set_V_calibrated_kts(double vc) {
 629     v_calibrated_kts = vc;
 630 }
 631
 632 void FGInterface::set_Mach_number(double mach) {
 633     mach_number = mach;
 634 }
 635
 636 void FGInterface::set_Velocities_Local( double north,
 637                                         double east,
 638                                         double down ){
 639     v_local_v[0] = north;
 640     v_local_v[1] = east;
 641     v_local_v[2] = down;
 642 }
 643
 644 void FGInterface::set_Velocities_Wind_Body( double u,
 645                                             double v,
 646                                             double w){
 647     v_wind_body_v[0] = u;
 648     v_wind_body_v[1] = v;
 649     v_wind_body_v[2] = w;
 650 }
 651
 652 // Euler angles
 653 void FGInterface::set_Euler_Angles( double phi,
 654                                     double theta,
 655                                     double psi ) {
 656     euler_angles_v[0] = phi;
 657     euler_angles_v[1] = theta;
 658     euler_angles_v[2] = psi;
 659 }
 660
 661 // Flight Path
 662 void FGInterface::set_Climb_Rate( double roc) {
 663     climb_rate = roc;
 664 }
 665
 666 void FGInterface::set_Gamma_vert_rad( double gamma) {
 667     gamma_vert_rad = gamma;
 668 }
 669
 670 void FGInterface::set_Static_pressure(double p) { static_pressure = p; }
 671 void FGInterface::set_Static_temperature(double T) { static_temperature = T; }
 672 void FGInterface::set_Density(double rho) { density = rho; }
 673
 674 void FGInterface::set_Velocities_Local_Airmass (double wnorth,
 675                                                 double weast,
 676                                                 double wdown ) {
 677     v_local_airmass_v[0] = wnorth;
 678     v_local_airmass_v[1] = weast;
 679     v_local_airmass_v[2] = wdown;
 680 }
 681
 682
 683 void FGInterface::_busdump(void) {
 684
 685     SG_LOG(SG_FLIGHT,SG_INFO,"d_pilot_rp_body_v[3]: " << d_pilot_rp_body_v[0] << ", " << d_pilot_rp_body_v[1] << ", " << d_pilot_rp_body_v[2]);
 686     SG_LOG(SG_FLIGHT,SG_INFO,"d_cg_rp_body_v[3]: " << d_cg_rp_body_v[0] << ", " << d_cg_rp_body_v[1] << ", " << d_cg_rp_body_v[2]);
 687     SG_LOG(SG_FLIGHT,SG_INFO,"f_body_total_v[3]: " << f_body_total_v[0] << ", " << f_body_total_v[1] << ", " << f_body_total_v[2]);
 688     SG_LOG(SG_FLIGHT,SG_INFO,"f_local_total_v[3]: " << f_local_total_v[0] << ", " << f_local_total_v[1] << ", " << f_local_total_v[2]);
 689     SG_LOG(SG_FLIGHT,SG_INFO,"f_aero_v[3]: " << f_aero_v[0] << ", " << f_aero_v[1] << ", " << f_aero_v[2]);
 690     SG_LOG(SG_FLIGHT,SG_INFO,"f_engine_v[3]: " << f_engine_v[0] << ", " << f_engine_v[1] << ", " << f_engine_v[2]);
 691     SG_LOG(SG_FLIGHT,SG_INFO,"f_gear_v[3]: " << f_gear_v[0] << ", " << f_gear_v[1] << ", " << f_gear_v[2]);
 692     SG_LOG(SG_FLIGHT,SG_INFO,"m_total_rp_v[3]: " << m_total_rp_v[0] << ", " << m_total_rp_v[1] << ", " << m_total_rp_v[2]);
 693     SG_LOG(SG_FLIGHT,SG_INFO,"m_total_cg_v[3]: " << m_total_cg_v[0] << ", " << m_total_cg_v[1] << ", " << m_total_cg_v[2]);
 694     SG_LOG(SG_FLIGHT,SG_INFO,"m_aero_v[3]: " << m_aero_v[0] << ", " << m_aero_v[1] << ", " << m_aero_v[2]);
 695     SG_LOG(SG_FLIGHT,SG_INFO,"m_engine_v[3]: " << m_engine_v[0] << ", " << m_engine_v[1] << ", " << m_engine_v[2]);
 696     SG_LOG(SG_FLIGHT,SG_INFO,"m_gear_v[3]: " << m_gear_v[0] << ", " << m_gear_v[1] << ", " << m_gear_v[2]);
 697     SG_LOG(SG_FLIGHT,SG_INFO,"v_dot_local_v[3]: " << v_dot_local_v[0] << ", " << v_dot_local_v[1] << ", " << v_dot_local_v[2]);
 698     SG_LOG(SG_FLIGHT,SG_INFO,"v_dot_body_v[3]: " << v_dot_body_v[0] << ", " << v_dot_body_v[1] << ", " << v_dot_body_v[2]);
 699     SG_LOG(SG_FLIGHT,SG_INFO,"a_cg_body_v[3]: " << a_cg_body_v[0] << ", " << a_cg_body_v[1] << ", " << a_cg_body_v[2]);
 700     SG_LOG(SG_FLIGHT,SG_INFO,"a_pilot_body_v[3]: " << a_pilot_body_v[0] << ", " << a_pilot_body_v[1] << ", " << a_pilot_body_v[2]);
 701     SG_LOG(SG_FLIGHT,SG_INFO,"n_cg_body_v[3]: " << n_cg_body_v[0] << ", " << n_cg_body_v[1] << ", " << n_cg_body_v[2]);
 702     SG_LOG(SG_FLIGHT,SG_INFO,"n_pilot_body_v[3]: " << n_pilot_body_v[0] << ", " << n_pilot_body_v[1] << ", " << n_pilot_body_v[2]);
 703     SG_LOG(SG_FLIGHT,SG_INFO,"omega_dot_body_v[3]: " << omega_dot_body_v[0] << ", " << omega_dot_body_v[1] << ", " << omega_dot_body_v[2]);
 704     SG_LOG(SG_FLIGHT,SG_INFO,"v_local_v[3]: " << v_local_v[0] << ", " << v_local_v[1] << ", " << v_local_v[2]);
 705     SG_LOG(SG_FLIGHT,SG_INFO,"v_local_rel_ground_v[3]: " << v_local_rel_ground_v[0] << ", " << v_local_rel_ground_v[1] << ", " << v_local_rel_ground_v[2]);
 706     SG_LOG(SG_FLIGHT,SG_INFO,"v_local_airmass_v[3]: " << v_local_airmass_v[0] << ", " << v_local_airmass_v[1] << ", " << v_local_airmass_v[2]);
 707     SG_LOG(SG_FLIGHT,SG_INFO,"v_local_rel_airmass_v[3]: " << v_local_rel_airmass_v[0] << ", " << v_local_rel_airmass_v[1] << ", " << v_local_rel_airmass_v[2]);
 708     SG_LOG(SG_FLIGHT,SG_INFO,"v_local_gust_v[3]: " << v_local_gust_v[0] << ", " << v_local_gust_v[1] << ", " << v_local_gust_v[2]);
 709     SG_LOG(SG_FLIGHT,SG_INFO,"v_wind_body_v[3]: " << v_wind_body_v[0] << ", " << v_wind_body_v[1] << ", " << v_wind_body_v[2]);
 710     SG_LOG(SG_FLIGHT,SG_INFO,"omega_body_v[3]: " << omega_body_v[0] << ", " << omega_body_v[1] << ", " << omega_body_v[2]);
 711     SG_LOG(SG_FLIGHT,SG_INFO,"omega_local_v[3]: " << omega_local_v[0] << ", " << omega_local_v[1] << ", " << omega_local_v[2]);
 712     SG_LOG(SG_FLIGHT,SG_INFO,"omega_total_v[3]: " << omega_total_v[0] << ", " << omega_total_v[1] << ", " << omega_total_v[2]);
 713     SG_LOG(SG_FLIGHT,SG_INFO,"euler_rates_v[3]: " << euler_rates_v[0] << ", " << euler_rates_v[1] << ", " << euler_rates_v[2]);
 714     SG_LOG(SG_FLIGHT,SG_INFO,"geocentric_rates_v[3]: " << geocentric_rates_v[0] << ", " << geocentric_rates_v[1] << ", " << geocentric_rates_v[2]);
 715     SG_LOG(SG_FLIGHT,SG_INFO,"geocentric_position_v[3]: " << geocentric_position_v[0] << ", " << geocentric_position_v[1] << ", " << geocentric_position_v[2]);
 716     SG_LOG(SG_FLIGHT,SG_INFO,"geodetic_position_v[3]: " << geodetic_position_v[0] << ", " << geodetic_position_v[1] << ", " << geodetic_position_v[2]);
 717     SG_LOG(SG_FLIGHT,SG_INFO,"euler_angles_v[3]: " << euler_angles_v[0] << ", " << euler_angles_v[1] << ", " << euler_angles_v[2]);
 718     SG_LOG(SG_FLIGHT,SG_INFO,"d_cg_rwy_local_v[3]: " << d_cg_rwy_local_v[0] << ", " << d_cg_rwy_local_v[1] << ", " << d_cg_rwy_local_v[2]);
 719     SG_LOG(SG_FLIGHT,SG_INFO,"d_cg_rwy_rwy_v[3]: " << d_cg_rwy_rwy_v[0] << ", " << d_cg_rwy_rwy_v[1] << ", " << d_cg_rwy_rwy_v[2]);
 720     SG_LOG(SG_FLIGHT,SG_INFO,"d_pilot_rwy_local_v[3]: " << d_pilot_rwy_local_v[0] << ", " << d_pilot_rwy_local_v[1] << ", " << d_pilot_rwy_local_v[2]);
 721     SG_LOG(SG_FLIGHT,SG_INFO,"d_pilot_rwy_rwy_v[3]: " << d_pilot_rwy_rwy_v[0] << ", " << d_pilot_rwy_rwy_v[1] << ", " << d_pilot_rwy_rwy_v[2]);
 722
 723     SG_LOG(SG_FLIGHT,SG_INFO,"t_local_to_body_m[0][3]: " << t_local_to_body_m[0][0] << ", " << t_local_to_body_m[0][1] << ", " << t_local_to_body_m[0][2]);
 724     SG_LOG(SG_FLIGHT,SG_INFO,"t_local_to_body_m[1][3]: " << t_local_to_body_m[1][0] << ", " << t_local_to_body_m[1][1] << ", " << t_local_to_body_m[1][2]);
 725     SG_LOG(SG_FLIGHT,SG_INFO,"t_local_to_body_m[2][3]: " << t_local_to_body_m[2][0] << ", " << t_local_to_body_m[2][1] << ", " << t_local_to_body_m[2][2]);
 726
 727     SG_LOG(SG_FLIGHT,SG_INFO,"mass: " << mass );
 728     SG_LOG(SG_FLIGHT,SG_INFO,"i_xx: " << i_xx );
 729     SG_LOG(SG_FLIGHT,SG_INFO,"i_yy: " << i_yy );
 730     SG_LOG(SG_FLIGHT,SG_INFO,"i_zz: " << i_zz );
 731     SG_LOG(SG_FLIGHT,SG_INFO,"i_xz: " << i_xz );
 732     SG_LOG(SG_FLIGHT,SG_INFO,"nlf: " << nlf );
 733     SG_LOG(SG_FLIGHT,SG_INFO,"v_rel_wind: " << v_rel_wind );
 734     SG_LOG(SG_FLIGHT,SG_INFO,"v_true_kts: " << v_true_kts );
 735     SG_LOG(SG_FLIGHT,SG_INFO,"v_rel_ground: " << v_rel_ground );
 736     SG_LOG(SG_FLIGHT,SG_INFO,"v_inertial: " << v_inertial );
 737     SG_LOG(SG_FLIGHT,SG_INFO,"v_ground_speed: " << v_ground_speed );
 738     SG_LOG(SG_FLIGHT,SG_INFO,"v_equiv: " << v_equiv );
 739     SG_LOG(SG_FLIGHT,SG_INFO,"v_equiv_kts: " << v_equiv_kts );
 740     SG_LOG(SG_FLIGHT,SG_INFO,"v_calibrated: " << v_calibrated );
 741     SG_LOG(SG_FLIGHT,SG_INFO,"v_calibrated_kts: " << v_calibrated_kts );
 742     SG_LOG(SG_FLIGHT,SG_INFO,"gravity: " << gravity );
 743     SG_LOG(SG_FLIGHT,SG_INFO,"centrifugal_relief: " << centrifugal_relief );
 744     SG_LOG(SG_FLIGHT,SG_INFO,"alpha: " << alpha );
 745     SG_LOG(SG_FLIGHT,SG_INFO,"beta: " << beta );
 746     SG_LOG(SG_FLIGHT,SG_INFO,"alpha_dot: " << alpha_dot );
 747     SG_LOG(SG_FLIGHT,SG_INFO,"beta_dot: " << beta_dot );
 748     SG_LOG(SG_FLIGHT,SG_INFO,"cos_alpha: " << cos_alpha );
 749     SG_LOG(SG_FLIGHT,SG_INFO,"sin_alpha: " << sin_alpha );
 750     SG_LOG(SG_FLIGHT,SG_INFO,"cos_beta: " << cos_beta );
 751     SG_LOG(SG_FLIGHT,SG_INFO,"sin_beta: " << sin_beta );
 752     SG_LOG(SG_FLIGHT,SG_INFO,"cos_phi: " << cos_phi );
 753     SG_LOG(SG_FLIGHT,SG_INFO,"sin_phi: " << sin_phi );
 754     SG_LOG(SG_FLIGHT,SG_INFO,"cos_theta: " << cos_theta );
 755     SG_LOG(SG_FLIGHT,SG_INFO,"sin_theta: " << sin_theta );
 756     SG_LOG(SG_FLIGHT,SG_INFO,"cos_psi: " << cos_psi );
 757     SG_LOG(SG_FLIGHT,SG_INFO,"sin_psi: " << sin_psi );
 758     SG_LOG(SG_FLIGHT,SG_INFO,"gamma_vert_rad: " << gamma_vert_rad );
 759     SG_LOG(SG_FLIGHT,SG_INFO,"gamma_horiz_rad: " << gamma_horiz_rad );
 760     SG_LOG(SG_FLIGHT,SG_INFO,"sigma: " << sigma );
 761     SG_LOG(SG_FLIGHT,SG_INFO,"density: " << density );
 762     SG_LOG(SG_FLIGHT,SG_INFO,"v_sound: " << v_sound );
 763     SG_LOG(SG_FLIGHT,SG_INFO,"mach_number: " << mach_number );
 764     SG_LOG(SG_FLIGHT,SG_INFO,"static_pressure: " << static_pressure );
 765     SG_LOG(SG_FLIGHT,SG_INFO,"total_pressure: " << total_pressure );
 766     SG_LOG(SG_FLIGHT,SG_INFO,"impact_pressure: " << impact_pressure );
 767     SG_LOG(SG_FLIGHT,SG_INFO,"dynamic_pressure: " << dynamic_pressure );
 768     SG_LOG(SG_FLIGHT,SG_INFO,"static_temperature: " << static_temperature );
 769     SG_LOG(SG_FLIGHT,SG_INFO,"total_temperature: " << total_temperature );
 770     SG_LOG(SG_FLIGHT,SG_INFO,"sea_level_radius: " << sea_level_radius );
 771     SG_LOG(SG_FLIGHT,SG_INFO,"earth_position_angle: " << earth_position_angle );
 772     SG_LOG(SG_FLIGHT,SG_INFO,"runway_altitude: " << runway_altitude );
 773     SG_LOG(SG_FLIGHT,SG_INFO,"runway_latitude: " << runway_latitude );
 774     SG_LOG(SG_FLIGHT,SG_INFO,"runway_longitude: " << runway_longitude );
 775     SG_LOG(SG_FLIGHT,SG_INFO,"runway_heading: " << runway_heading );
 776     SG_LOG(SG_FLIGHT,SG_INFO,"radius_to_rwy: " << radius_to_rwy );
 777     SG_LOG(SG_FLIGHT,SG_INFO,"climb_rate: " << climb_rate );
 778     SG_LOG(SG_FLIGHT,SG_INFO,"sin_lat_geocentric: " << sin_lat_geocentric );
 779     SG_LOG(SG_FLIGHT,SG_INFO,"cos_lat_geocentric: " << cos_lat_geocentric );
 780     SG_LOG(SG_FLIGHT,SG_INFO,"sin_longitude: " << sin_longitude );
 781     SG_LOG(SG_FLIGHT,SG_INFO,"cos_longitude: " << cos_longitude );
 782     SG_LOG(SG_FLIGHT,SG_INFO,"sin_latitude: " << sin_latitude );
 783     SG_LOG(SG_FLIGHT,SG_INFO,"cos_latitude: " << cos_latitude );
 784     SG_LOG(SG_FLIGHT,SG_INFO,"altitude_agl: " << altitude_agl );
 785 }
 786
 787 bool
 788 FGInterface::prepare_ground_cache_m(double ref_time, const double pt[3],
 789                                     double rad)
 790 {
 791   return ground_cache.prepare_ground_cache(ref_time, pt, rad);
 792 }
 793
 794 bool FGInterface::prepare_ground_cache_ft(double ref_time, const double pt[3],
 795                                           double rad)
 796 {
 797   // Convert units and do the real work.
 798   sgdVec3 pt_ft;
 799   sgdScaleVec3( pt_ft, pt, SG_FEET_TO_METER );
 800   return ground_cache.prepare_ground_cache(ref_time, pt_ft, rad*SG_FEET_TO_METER);
 801 }
 802
 803 bool
 804 FGInterface::is_valid_m(double *ref_time, double pt[3], double *rad)
 805 {
 806   return ground_cache.is_valid(ref_time, pt, rad);
 807 }
 808
 809 bool FGInterface::is_valid_ft(double *ref_time, double pt[3], double *rad)
 810 {
 811   // Convert units and do the real work.
 812   bool found_ground = ground_cache.is_valid(ref_time, pt, rad);
 813   sgdScaleVec3(pt, SG_METER_TO_FEET);
 814   *rad *= SG_METER_TO_FEET;
 815   return found_ground;
 816 }
 817
 818 double
 819 FGInterface::get_cat_m(double t, const double pt[3],
 820                        double end[2][3], double vel[2][3])
 821 {
 822   return ground_cache.get_cat(t, pt, end, vel);
 823 }
 824
 825 double
 826 FGInterface::get_cat_ft(double t, const double pt[3],
 827                         double end[2][3], double vel[2][3])
 828 {
 829   // Convert units and do the real work.
 830   sgdVec3 pt_m;
 831   sgdScaleVec3( pt_m, pt, SG_FEET_TO_METER );
 832   double dist = ground_cache.get_cat(t, pt_m, end, vel);
 833   for (int k=0; k<2; ++k) {
 834     sgdScaleVec3( end[k], SG_METER_TO_FEET );
 835     sgdScaleVec3( vel[k], SG_METER_TO_FEET );
 836   }
 837   return dist*SG_METER_TO_FEET;
 838 }
 839
 840 // Legacy interface just kept because of JSBSim
 841 bool
 842 FGInterface::get_agl_m(double t, const double pt[3],
 843                        double contact[3], double normal[3], double vel[3],
 844                        int *type, double *loadCapacity,
 845                        double *frictionFactor, double *agl)
 846 {
 847   const SGMaterial* material;
 848   bool ret = ground_cache.get_agl(t, pt, 2.0, contact, normal, vel, type,
 849                                   &material, agl);
 850   if (material) {
 851     *loadCapacity = material->get_load_resistence();
 852     *frictionFactor = material->get_friction_factor();
 853
 854   } else {
 855     *loadCapacity = DBL_MAX;
 856     *frictionFactor = 1.0;
 857   }
 858   return ret;
 859 }
 860
 861 // Legacy interface just kept because of JSBSim
 862 bool
 863 FGInterface::get_agl_ft(double t, const double pt[3],
 864                         double contact[3], double normal[3], double vel[3],
 865                         int *type, double *loadCapacity,
 866                         double *frictionFactor, double *agl)
 867 {
 868   // Convert units and do the real work.
 869   sgdVec3 pt_m;
 870   sgdScaleVec3( pt_m, pt, SG_FEET_TO_METER );
 871
 872   const SGMaterial* material;
 873   bool ret = ground_cache.get_agl(t, pt_m, 2.0, contact, normal, vel,
 874                                   type, &material, agl);
 875   // Convert units back ...
 876   sgdScaleVec3( contact, SG_METER_TO_FEET );
 877   sgdScaleVec3( vel, SG_METER_TO_FEET );
 878   *agl *= SG_METER_TO_FEET;
 879
 880   // return material properties if available
 881   if (material) {
 882     // FIXME: convert units?? now pascal to lbf/ft^2
 883     *loadCapacity = 0.020885434*material->get_load_resistence();
 884     *frictionFactor = material->get_friction_factor();
 885   } else {
 886     *loadCapacity = DBL_MAX;
 887     *frictionFactor = 1.0;
 888   }
 889   return ret;
 890 }
 891
 892 bool
 893 FGInterface::get_agl_m(double t, const double pt[3], double max_altoff,
 894                        double contact[3], double normal[3], double vel[3],
 895                        int *type, const SGMaterial** material, double *agl)
 896 {
 897   return ground_cache.get_agl(t, pt, max_altoff, contact, normal, vel, type,
 898                               material, agl);
 899 }
 900
 901 bool
 902 FGInterface::get_agl_ft(double t, const double pt[3], double max_altoff,
 903                         double contact[3], double normal[3], double vel[3],
 904                         int *type, const SGMaterial** material, double *agl)
 905 {
 906   // Convert units and do the real work.
 907   sgdVec3 pt_m;
 908   sgdScaleVec3( pt_m, pt, SG_FEET_TO_METER );
 909   bool ret = ground_cache.get_agl(t, pt_m, SG_FEET_TO_METER * max_altoff,
 910                                   contact, normal, vel,
 911                                   type, material, agl);
 912   // Convert units back ...
 913   sgdScaleVec3( contact, SG_METER_TO_FEET );
 914   sgdScaleVec3( vel, SG_METER_TO_FEET );
 915   *agl *= SG_METER_TO_FEET;
 916   return ret;
 917 }
 918
 919
 920 double
 921 FGInterface::get_groundlevel_m(double lat, double lon, double alt)
 922 {
 923   sgdVec3 pos, cpos;
 924   // Compute the cartesian position of the given lat/lon/alt.
 925   sgGeodToCart(lat, lon, alt, pos);
 926
 927   // FIXME: how to handle t - ref_time differences ???
 928   double ref_time, radius;
 929   // Prepare the ground cache for that position.
 930   if (!is_valid_m(&ref_time, cpos, &radius)) {
 931     bool ok = prepare_ground_cache_m(ref_time, pos, 10);
 932     /// This is most likely the case when the given altitude is
 933     /// too low, try with a new altitude of 10000m, that should be
 934     /// sufficient to find a ground level below everywhere on our planet
 935     if (!ok) {
 936       sgGeodToCart(lat, lon, 10000, pos);
 937       /// If there is still no ground, return sea level radius
 938       if (!prepare_ground_cache_m(ref_time, pos, 10))
 939         return 0;
 940     }
 941   } else if (radius*radius <= sgdDistanceSquaredVec3(pos, cpos)) {
 942     /// We reuse the old radius value, but only if it is at least 10 Meters ..
 943     if (!(10 < radius)) // Well this strange compare is nan safe
 944       radius = 10;
 945
 946     bool ok = prepare_ground_cache_m(ref_time, pos, radius);
 947     /// This is most likely the case when the given altitude is
 948     /// too low, try with a new altitude of 10000m, that should be
 949     /// sufficient to find a ground level below everywhere on our planet
 950     if (!ok) {
 951       sgGeodToCart(lat, lon, 10000, pos);
 952       /// If there is still no ground, return sea level radius
 953       if (!prepare_ground_cache_m(ref_time, pos, radius))
 954         return 0;
 955     }
 956   }
 957
 958   double contact[3], normal[3], vel[3], agl;
 959   int type;
 960   // Ignore the return value here, since it just tells us if
 961   // the returns stem from the groundcache or from the coarse
 962   // computations below the groundcache. The contact point is still something
 963   // valid, the normals and the other returns just contain some defaults.
 964   get_agl_m(ref_time, pos, 2.0, contact, normal, vel, &type, 0, &agl);
 965   Point3D geodPos = sgCartToGeod(Point3D(contact[0], contact[1], contact[2]));
 966   return geodPos.elev();
 967 }
 968
 969 bool
 970 FGInterface::caught_wire_m(double t, const double pt[4][3])
 971 {
 972   return ground_cache.caught_wire(t, pt);
 973 }
 974
 975 bool
 976 FGInterface::caught_wire_ft(double t, const double pt[4][3])
 977 {
 978   // Convert units and do the real work.
 979   double pt_m[4][3];
 980   for (int i=0; i<4; ++i)
 981     sgdScaleVec3(pt_m[i], pt[i], SG_FEET_TO_METER);
 982
 983   return ground_cache.caught_wire(t, pt_m);
 984 }
 985
 986 bool
 987 FGInterface::get_wire_ends_m(double t, double end[2][3], double vel[2][3])
 988 {
 989   return ground_cache.get_wire_ends(t, end, vel);
 990 }
 991
 992 bool
 993 FGInterface::get_wire_ends_ft(double t, double end[2][3], double vel[2][3])
 994 {
 995   // Convert units and do the real work.
 996   bool ret = ground_cache.get_wire_ends(t, end, vel);
 997   for (int k=0; k<2; ++k) {
 998     sgdScaleVec3( end[k], SG_METER_TO_FEET );
 999     sgdScaleVec3( vel[k], SG_METER_TO_FEET );
1000   }
1001   return ret;
1002 }
1003
1004 void
1005 FGInterface::release_wire(void)
1006 {
1007   ground_cache.release_wire();
1008 }
1009
1010 void fgToggleFDMdataLogging(void) {
1011   cur_fdm_state->ToggleDataLogging();
1012 }