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., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 //
  21 // $Id$
  22
  23
  24 #include <stdio.h>
  25
  26 #include <plib/sg.h>
  27
  28 #include <simgear/constants.h>
  29 #include <simgear/debug/logstream.hxx>
  30 #include <simgear/math/sg_geodesy.hxx>
  31 #include <simgear/scene/model/placement.hxx>
  32 #include <simgear/timing/timestamp.hxx>
  33
  34 #include <Scenery/scenery.hxx>
  35 #include <Main/globals.hxx>
  36 #include <Main/fg_props.hxx>
  37 #include <FDM/groundcache.hxx>
  38
  39 #include "flight.hxx"
  40
  41
  42 // base_fdm_state is the internal state that is updated in integer
  43 // multiples of "dt".  This leads to "jitter" with respect to the real
  44 // world time, so we introduce cur_fdm_state which is extrapolated by
  45 // the difference between sim time and real world time
  46
  47 FGInterface *cur_fdm_state = 0;
  48 FGInterface base_fdm_state;
  49
  50 inline void init_vec(FG_VECTOR_3 vec) {
  51     vec[0] = 0.0; vec[1] = 0.0; vec[2] = 0.0;
  52 }
  53
  54 // Constructor
  55 FGInterface::FGInterface()
  56   : remainder(0)
  57 {
  58     _setup();
  59 }
  60
  61 FGInterface::FGInterface( double dt )
  62   : remainder(0)
  63 {
  64     _setup();
  65 }
  66
  67 // Destructor
  68 FGInterface::~FGInterface() {
  69     // unbind();                   // FIXME: should be called explicitly
  70 }
  71
  72
  73 int
  74 FGInterface::_calc_multiloop (double dt)
  75 {
  76   int hz = fgGetInt("/sim/model-hz");
  77   int speedup = fgGetInt("/sim/speed-up");
  78
  79   dt += remainder;
  80   remainder = 0;
  81   double ml = dt * hz;
  82   // Avoid roundoff problems by adding the roundoff itself.
  83   // ... ok, two times the roundoff to have enough room.
  84   int multiloop = int(floor(ml * (1.0 + 2.0*DBL_EPSILON)));
  85   remainder = (ml - multiloop) / hz;
  86   return (multiloop * speedup);
  87 }
  88
  89
  90 /**
  91  * Set default values for the state of the FDM.
  92  *
  93  * This method is invoked by the constructors.
  94  */
  95 void
  96 FGInterface::_setup ()
  97 {
  98     inited = false;
  99     bound = false;
 100
 101     init_vec( d_pilot_rp_body_v );
 102     init_vec( d_cg_rp_body_v );
 103     init_vec( f_body_total_v );
 104     init_vec( f_local_total_v );
 105     init_vec( f_aero_v );
 106     init_vec( f_engine_v );
 107     init_vec( f_gear_v );
 108     init_vec( m_total_rp_v );
 109     init_vec( m_total_cg_v );
 110     init_vec( m_aero_v );
 111     init_vec( m_engine_v );
 112     init_vec( m_gear_v );
 113     init_vec( v_dot_local_v );
 114     init_vec( v_dot_body_v );
 115     init_vec( a_cg_body_v );
 116     init_vec( a_pilot_body_v );
 117     init_vec( n_cg_body_v );
 118     init_vec( n_pilot_body_v );
 119     init_vec( omega_dot_body_v );
 120     init_vec( v_local_v );
 121     init_vec( v_local_rel_ground_v );
 122     init_vec( v_local_airmass_v );
 123     init_vec( v_local_rel_airmass_v );
 124     init_vec( v_local_gust_v );
 125     init_vec( v_wind_body_v );
 126     init_vec( omega_body_v );
 127     init_vec( omega_local_v );
 128     init_vec( omega_total_v );
 129     init_vec( euler_rates_v );
 130     init_vec( geocentric_rates_v );
 131     init_vec( geocentric_position_v );
 132     init_vec( geodetic_position_v );
 133     init_vec( euler_angles_v );
 134     init_vec( d_cg_rwy_local_v );
 135     init_vec( d_cg_rwy_rwy_v );
 136     init_vec( d_pilot_rwy_local_v );
 137     init_vec( d_pilot_rwy_rwy_v );
 138     init_vec( t_local_to_body_m[0] );
 139     init_vec( t_local_to_body_m[1] );
 140     init_vec( t_local_to_body_m[2] );
 141
 142     mass=i_xx=i_yy=i_zz=i_xz=0;
 143     nlf=0;
 144     v_rel_wind=v_true_kts=v_rel_ground=v_inertial=0;
 145     v_ground_speed=v_equiv=v_equiv_kts=0;
 146     v_calibrated=v_calibrated_kts=0;
 147     gravity=0;
 148     centrifugal_relief=0;
 149     alpha=beta=alpha_dot=beta_dot=0;
 150     cos_alpha=sin_alpha=cos_beta=sin_beta=0;
 151     cos_phi=sin_phi=cos_theta=sin_theta=cos_psi=sin_psi=0;
 152     gamma_vert_rad=gamma_horiz_rad=0;
 153     sigma=density=v_sound=mach_number=0;
 154     static_pressure=total_pressure=impact_pressure=0;
 155     dynamic_pressure=0;
 156     static_temperature=total_temperature=0;
 157     sea_level_radius=earth_position_angle=0;
 158     runway_altitude=runway_latitude=runway_longitude=0;
 159     runway_heading=0;
 160     radius_to_rwy=0;
 161     climb_rate=0;
 162     sin_lat_geocentric=cos_lat_geocentric=0;
 163     sin_latitude=cos_latitude=0;
 164     sin_longitude=cos_longitude=0;
 165     altitude_agl=0;
 166 }
 167
 168 void
 169 FGInterface::init () {}
 170
 171 /**
 172  * Initialize the state of the FDM.
 173  *
 174  * Subclasses of FGInterface may do their own, additional initialization,
 175  * but there is some that is common to all.  Normally, they should call
 176  * this before they begin their own init to make sure the basic structures
 177  * are set up properly.
 178  */
 179 void
 180 FGInterface::common_init ()
 181 {
 182     SG_LOG( SG_FLIGHT, SG_INFO, "Start common FDM init" );
 183
 184     set_inited( true );
 185
 186 //     stamp();
 187 //     set_remainder( 0 );
 188
 189     // Set initial position
 190     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing position..." );
 191     double lon = fgGetDouble("/sim/presets/longitude-deg")
 192       * SGD_DEGREES_TO_RADIANS;
 193     double lat = fgGetDouble("/sim/presets/latitude-deg")
 194       * SGD_DEGREES_TO_RADIANS;
 195     double alt_ft = fgGetDouble("/sim/presets/altitude-ft");
 196     double alt_m = alt_ft * SG_FEET_TO_METER;
 197     set_Longitude( lon );
 198     set_Latitude( lat );
 199
 200     double ground_elev_m = get_groundlevel_m(lat, lon, alt_m);
 201     double ground_elev_ft = ground_elev_m * SG_METER_TO_FEET;
 202     _set_Runway_altitude ( ground_elev_ft );
 203     if ( fgGetBool("/sim/presets/onground") || alt_ft < ground_elev_ft ) {
 204         fgSetDouble("/position/altitude-ft", ground_elev_ft + 0.1);
 205         set_Altitude( ground_elev_ft + 0.1);
 206     } else {
 207         set_Altitude( alt_ft );
 208     }
 209
 210     // Set ground elevation
 211     SG_LOG( SG_FLIGHT, SG_INFO,
 212             "...initializing ground elevation to " << ground_elev_ft
 213             << "ft..." );
 214
 215     // Set sea-level radius
 216     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing sea-level radius..." );
 217     SG_LOG( SG_FLIGHT, SG_INFO, " lat = "
 218             << fgGetDouble("/sim/presets/latitude-deg")
 219             << " alt = " << get_Altitude() );
 220     double sea_level_radius_meters;
 221     double lat_geoc;
 222     sgGeodToGeoc( fgGetDouble("/sim/presets/latitude-deg")
 223                     * SGD_DEGREES_TO_RADIANS,
 224                   get_Altitude() * SG_FEET_TO_METER,
 225                   &sea_level_radius_meters, &lat_geoc );
 226     _set_Sea_level_radius( sea_level_radius_meters * SG_METER_TO_FEET );
 227
 228     // Set initial velocities
 229     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing velocities..." );
 230     if ( !fgHasNode("/sim/presets/speed-set") ) {
 231         set_V_calibrated_kts(0.0);
 232     } else {
 233         const string speedset = fgGetString("/sim/presets/speed-set");
 234         if ( speedset == "knots" || speedset == "KNOTS" ) {
 235             set_V_calibrated_kts( fgGetDouble("/sim/presets/airspeed-kt") );
 236         } else if ( speedset == "mach" || speedset == "MACH" ) {
 237             set_Mach_number( fgGetDouble("/sim/presets/mach") );
 238         } else if ( speedset == "UVW" || speedset == "uvw" ) {
 239             set_Velocities_Wind_Body(
 240                                      fgGetDouble("/sim/presets/uBody-fps"),
 241                                      fgGetDouble("/sim/presets/vBody-fps"),
 242                                      fgGetDouble("/sim/presets/wBody-fps") );
 243         } else if ( speedset == "NED" || speedset == "ned" ) {
 244             set_Velocities_Local(
 245                                  fgGetDouble("/sim/presets/speed-north-fps"),
 246                                  fgGetDouble("/sim/presets/speed-east-fps"),
 247                                  fgGetDouble("/sim/presets/speed-down-fps") );
 248         } else {
 249             SG_LOG( SG_FLIGHT, SG_ALERT,
 250                     "Unrecognized value for /sim/presets/speed-set: "
 251                     << speedset);
 252             set_V_calibrated_kts( 0.0 );
 253         }
 254     }
 255
 256     // Set initial Euler angles
 257     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing Euler angles..." );
 258     set_Euler_Angles( fgGetDouble("/sim/presets/roll-deg")
 259                         * SGD_DEGREES_TO_RADIANS,
 260                       fgGetDouble("/sim/presets/pitch-deg")
 261                         * SGD_DEGREES_TO_RADIANS,
 262                       fgGetDouble("/sim/presets/heading-deg")
 263                         * SGD_DEGREES_TO_RADIANS );
 264
 265     SG_LOG( SG_FLIGHT, SG_INFO, "End common FDM init" );
 266 }
 267
 268
 269 /**
 270  * Bind getters and setters to properties.
 271  *
 272  * The bind() method will be invoked after init().  Note that unlike
 273  * the usual implementations of FGSubsystem::bind(), this method does
 274  * not automatically pick up existing values for the properties at
 275  * bind time; instead, all values are set explicitly in the init()
 276  * method.
 277  */
 278 void
 279 FGInterface::bind ()
 280 {
 281   bound = true;
 282
 283                                 // Time management (read-only)
 284 //   fgTie("/fdm/time/delta_t", this,
 285 //         &FGInterface::get_delta_t); // read-only
 286 //   fgTie("/fdm/time/elapsed", this,
 287 //         &FGInterface::get_elapsed); // read-only
 288 //   fgTie("/fdm/time/remainder", this,
 289 //         &FGInterface::get_remainder); // read-only
 290 //   fgTie("/fdm/time/multi_loop", this,
 291 //         &FGInterface::get_multi_loop); // read-only
 292
 293                         // Aircraft position
 294   fgTie("/position/latitude-deg", this,
 295         &FGInterface::get_Latitude_deg,
 296         &FGInterface::set_Latitude_deg,
 297         false);
 298   fgSetArchivable("/position/latitude-deg");
 299   fgTie("/position/longitude-deg", this,
 300         &FGInterface::get_Longitude_deg,
 301         &FGInterface::set_Longitude_deg,
 302         false);
 303   fgSetArchivable("/position/longitude-deg");
 304   fgTie("/position/altitude-ft", this,
 305         &FGInterface::get_Altitude,
 306         &FGInterface::set_Altitude,
 307         false);
 308   fgSetArchivable("/position/altitude-ft");
 309   fgTie("/position/altitude-agl-ft", this,
 310         &FGInterface::get_Altitude_AGL); // read-only
 311   fgSetArchivable("/position/ground-elev-ft");
 312   fgTie("/position/ground-elev-ft", this,
 313         &FGInterface::get_Runway_altitude); // read-only
 314   fgSetArchivable("/position/ground-elev-m");
 315   fgTie("/position/ground-elev-m", this,
 316         &FGInterface::get_Runway_altitude_m); // read-only
 317   fgTie("/environment/ground-elevation-m", this,
 318         &FGInterface::get_Runway_altitude_m); // read-only
 319   fgSetArchivable("/position/sea-level-radius-ft");
 320   fgTie("/position/sea-level-radius-ft", this,
 321         &FGInterface::get_Sea_level_radius); // read-only
 322
 323                                 // Orientation
 324   fgTie("/orientation/roll-deg", this,
 325         &FGInterface::get_Phi_deg,
 326         &FGInterface::set_Phi_deg);
 327   fgSetArchivable("/orientation/roll-deg");
 328   fgTie("/orientation/pitch-deg", this,
 329         &FGInterface::get_Theta_deg,
 330         &FGInterface::set_Theta_deg);
 331   fgSetArchivable("/orientation/pitch-deg");
 332   fgTie("/orientation/heading-deg", this,
 333         &FGInterface::get_Psi_deg,
 334         &FGInterface::set_Psi_deg);
 335   fgSetArchivable("/orientation/heading-deg");
 336
 337   // Body-axis "euler rates" (rotation speed, but in a funny
 338   // representation).
 339   fgTie("/orientation/roll-rate-degps", this,
 340         &FGInterface::get_Phi_dot_degps);
 341   fgTie("/orientation/pitch-rate-degps", this,
 342         &FGInterface::get_Theta_dot_degps);
 343   fgTie("/orientation/yaw-rate-degps", this,
 344         &FGInterface::get_Psi_dot_degps);
 345
 346                                 // Calibrated airspeed
 347   fgTie("/velocities/airspeed-kt", this,
 348         &FGInterface::get_V_calibrated_kts,
 349         &FGInterface::set_V_calibrated_kts,
 350         false);
 351
 352                                 // Mach number
 353   fgTie("/velocities/mach", this,
 354         &FGInterface::get_Mach_number,
 355         &FGInterface::set_Mach_number,
 356         false);
 357
 358                                 // Local velocities
 359 //   fgTie("/velocities/speed-north-fps", this,
 360 //      &FGInterface::get_V_north,
 361 //      &FGInterface::set_V_north);
 362 //   fgSetArchivable("/velocities/speed-north-fps");
 363 //   fgTie("/velocities/speed-east-fps", this,
 364 //      &FGInterface::get_V_east,
 365 //      &FGInterface::set_V_east);
 366 //   fgSetArchivable("/velocities/speed-east-fps");
 367 //   fgTie("/velocities/speed-down-fps", this,
 368 //      &FGInterface::get_V_down,
 369 //      &FGInterface::set_V_down);
 370 //   fgSetArchivable("/velocities/speed-down-fps");
 371                                 // FIXME: Temporarily read-only, until the
 372                                 // incompatibilities between JSBSim and
 373                                 // LaRCSim are fixed (LaRCSim adds the
 374                                 // earth's rotation to the east velocity).
 375   fgTie("/velocities/speed-north-fps", this,
 376         &FGInterface::get_V_north);
 377   fgTie("/velocities/speed-east-fps", this,
 378         &FGInterface::get_V_east);
 379   fgTie("/velocities/speed-down-fps", this,
 380         &FGInterface::get_V_down);
 381
 382                                 // Relative wind
 383                                 // FIXME: temporarily archivable, until
 384                                 // the NED problem is fixed.
 385   fgTie("/velocities/uBody-fps", this,
 386         &FGInterface::get_uBody,
 387         &FGInterface::set_uBody,
 388         false);
 389   fgSetArchivable("/velocities/uBody-fps");
 390   fgTie("/velocities/vBody-fps", this,
 391         &FGInterface::get_vBody,
 392         &FGInterface::set_vBody,
 393         false);
 394   fgSetArchivable("/velocities/vBody-fps");
 395   fgTie("/velocities/wBody-fps", this,
 396         &FGInterface::get_wBody,
 397         &FGInterface::set_wBody,
 398         false);
 399   fgSetArchivable("/velocities/wBody-fps");
 400
 401                                 // Climb and slip (read-only)
 402   fgTie("/velocities/vertical-speed-fps", this,
 403         &FGInterface::get_Climb_Rate,
 404   &FGInterface::set_Climb_Rate );
 405   fgTie("/velocities/glideslope", this,
 406   &FGInterface::get_Gamma_vert_rad,
 407   &FGInterface::set_Gamma_vert_rad );
 408   fgTie("/orientation/side-slip-rad", this,
 409         &FGInterface::get_Beta); // read-only
 410   fgTie("/orientation/side-slip-deg", this,
 411   &FGInterface::get_Beta_deg); // read-only
 412   fgTie("/orientation/alpha-deg", this,
 413   &FGInterface::get_Alpha_deg); // read-only
 414   fgTie("/accelerations/nlf", this,
 415   &FGInterface::get_Nlf); // read-only
 416
 417                                 // NED accelerations
 418   fgTie("/accelerations/ned/north-accel-fps_sec",
 419         this, &FGInterface::get_V_dot_north);
 420   fgTie("/accelerations/ned/east-accel-fps_sec",
 421         this, &FGInterface::get_V_dot_east);
 422   fgTie("/accelerations/ned/down-accel-fps_sec",
 423         this, &FGInterface::get_V_dot_down);
 424
 425                                 // Pilot accelerations
 426   fgTie("/accelerations/pilot/x-accel-fps_sec",
 427         this, &FGInterface::get_A_X_pilot);
 428   fgTie("/accelerations/pilot/y-accel-fps_sec",
 429         this, &FGInterface::get_A_Y_pilot);
 430   fgTie("/accelerations/pilot/z-accel-fps_sec",
 431         this, &FGInterface::get_A_Z_pilot);
 432
 433 }
 434
 435
 436 /**
 437  * Unbind any properties bound to this FDM.
 438  *
 439  * This method allows the FDM to release properties so that a new
 440  * FDM can bind them instead.
 441  */
 442 void
 443 FGInterface::unbind ()
 444 {
 445   bound = false;
 446
 447   // fgUntie("/fdm/time/delta_t");
 448   // fgUntie("/fdm/time/elapsed");
 449   // fgUntie("/fdm/time/remainder");
 450   // fgUntie("/fdm/time/multi_loop");
 451   fgUntie("/position/latitude-deg");
 452   fgUntie("/position/longitude-deg");
 453   fgUntie("/position/altitude-ft");
 454   fgUntie("/position/altitude-agl-ft");
 455   fgUntie("/position/ground-elev-ft");
 456   fgUntie("/position/ground-elev-m");
 457   fgUntie("/environment/ground-elevation-m");
 458   fgUntie("/position/sea-level-radius-ft");
 459   fgUntie("/orientation/roll-deg");
 460   fgUntie("/orientation/pitch-deg");
 461   fgUntie("/orientation/heading-deg");
 462   fgUntie("/orientation/roll-rate-degps");
 463   fgUntie("/orientation/pitch-rate-degps");
 464   fgUntie("/orientation/yaw-rate-degps");
 465   fgUntie("/orientation/side-slip-rad");
 466   fgUntie("/orientation/side-slip-deg");
 467   fgUntie("/orientation/alpha-deg");
 468   fgUntie("/velocities/airspeed-kt");
 469   fgUntie("/velocities/mach");
 470   fgUntie("/velocities/speed-north-fps");
 471   fgUntie("/velocities/speed-east-fps");
 472   fgUntie("/velocities/speed-down-fps");
 473   fgUntie("/velocities/uBody-fps");
 474   fgUntie("/velocities/vBody-fps");
 475   fgUntie("/velocities/wBody-fps");
 476   fgUntie("/velocities/vertical-speed-fps");
 477   fgUntie("/velocities/glideslope");
 478   fgUntie("/accelerations/nlf");
 479   fgUntie("/accelerations/pilot/x-accel-fps_sec");
 480   fgUntie("/accelerations/pilot/y-accel-fps_sec");
 481   fgUntie("/accelerations/pilot/z-accel-fps_sec");
 482   fgUntie("/accelerations/ned/north-accel-fps_sec");
 483   fgUntie("/accelerations/ned/east-accel-fps_sec");
 484   fgUntie("/accelerations/ned/down-accel-fps_sec");
 485 }
 486
 487 /**
 488  * Update the state of the FDM (i.e. run the equations of motion).
 489  */
 490 void
 491 FGInterface::update (double dt)
 492 {
 493     SG_LOG(SG_FLIGHT, SG_ALERT, "dummy update() ... SHOULDN'T BE CALLED!");
 494 }
 495
 496
 497 void FGInterface::_updateGeodeticPosition( double lat, double lon, double alt )
 498 {
 499     double lat_geoc, sl_radius;
 500
 501     // cout << "starting sea level rad = " << get_Sea_level_radius() << endl;
 502
 503     sgGeodToGeoc( lat, alt * SG_FEET_TO_METER, &sl_radius, &lat_geoc );
 504
 505     SG_LOG( SG_FLIGHT, SG_DEBUG, "lon = " << lon
 506             << " lat_geod = " << lat
 507             << " lat_geoc = " << lat_geoc
 508             << " alt = " << alt
 509             << " sl_radius = " << sl_radius * SG_METER_TO_FEET
 510             << " Equator = " << SG_EQUATORIAL_RADIUS_FT );
 511
 512     _set_Geocentric_Position( lat_geoc, lon,
 513                               sl_radius * SG_METER_TO_FEET + alt );
 514
 515     _set_Geodetic_Position( lat, lon, alt );
 516
 517     _set_Sea_level_radius( sl_radius * SG_METER_TO_FEET );
 518     _update_ground_elev_at_pos();
 519
 520     _set_sin_lat_geocentric( lat_geoc );
 521     _set_cos_lat_geocentric( lat_geoc );
 522
 523     _set_sin_cos_longitude( lon );
 524
 525     _set_sin_cos_latitude( lat );
 526 }
 527
 528
 529 void FGInterface::_updateGeocentricPosition( double lat_geoc, double lon,
 530                                              double alt )
 531 {
 532     double lat_geod, tmp_alt, sl_radius1, sl_radius2, tmp_lat_geoc;
 533
 534     // cout << "starting sea level rad = " << get_Sea_level_radius() << endl;
 535
 536     sgGeocToGeod( lat_geoc, ( get_Sea_level_radius() + alt ) * SG_FEET_TO_METER,
 537                   &lat_geod, &tmp_alt, &sl_radius1 );
 538     sgGeodToGeoc( lat_geod, alt * SG_FEET_TO_METER, &sl_radius2, &tmp_lat_geoc );
 539
 540     SG_LOG( SG_FLIGHT, SG_DEBUG, "lon = " << lon
 541             << " lat_geod = " << lat_geod
 542             << " lat_geoc = " << lat_geoc
 543             << " alt = " << alt
 544             << " tmp_alt = " << tmp_alt * SG_METER_TO_FEET
 545             << " sl_radius1 = " << sl_radius1 * SG_METER_TO_FEET
 546             << " sl_radius2 = " << sl_radius2 * SG_METER_TO_FEET
 547             << " Equator = " << SG_EQUATORIAL_RADIUS_FT );
 548
 549     _set_Geocentric_Position( lat_geoc, lon,
 550                               sl_radius2 * SG_METER_TO_FEET + alt );
 551
 552     _set_Geodetic_Position( lat_geod, lon, alt );
 553
 554     _set_Sea_level_radius( sl_radius2 * SG_METER_TO_FEET );
 555     _update_ground_elev_at_pos();
 556
 557     _set_sin_lat_geocentric( lat_geoc );
 558     _set_cos_lat_geocentric( lat_geoc );
 559
 560     _set_sin_cos_longitude( lon );
 561
 562     _set_sin_cos_latitude( lat_geod );
 563 }
 564
 565 void FGInterface::_update_ground_elev_at_pos( void ) {
 566     double lat = get_Latitude();
 567     double lon = get_Longitude();
 568     double alt_m = get_Altitude()*SG_FEET_TO_METER;
 569     double groundlevel_m = get_groundlevel_m(lat, lon, alt_m);
 570     _set_Runway_altitude( groundlevel_m * SG_METER_TO_FEET );
 571 }
 572
 573 // Extrapolate fdm based on time_offset (in usec)
 574 void FGInterface::extrapolate( int time_offset ) {
 575     double dt = time_offset / 1000000.0;
 576
 577     // -dw- metrowerks complains about ambiguous access, not critical
 578     // to keep this ;)
 579 #ifndef __MWERKS__
 580     SG_LOG(SG_FLIGHT, SG_INFO, "extrapolating FDM by dt = " << dt);
 581 #endif
 582
 583     double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
 584     double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
 585
 586     double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
 587     double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
 588
 589     double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
 590     double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
 591
 592     geodetic_position_v[0] = lat;
 593     geocentric_position_v[0] = lat_geoc;
 594
 595     geodetic_position_v[1] = lon;
 596     geocentric_position_v[1] = lon_geoc;
 597
 598     geodetic_position_v[2] = alt;
 599     geocentric_position_v[2] = radius;
 600 }
 601
 602 // Positions
 603 void FGInterface::set_Latitude(double lat) {
 604     geodetic_position_v[0] = lat;
 605 }
 606
 607 void FGInterface::set_Longitude(double lon) {
 608     geodetic_position_v[1] = lon;
 609 }
 610
 611 void FGInterface::set_Altitude(double alt) {
 612     geodetic_position_v[2] = alt;
 613 }
 614
 615 void FGInterface::set_AltitudeAGL(double altagl) {
 616     altitude_agl=altagl;
 617 }
 618
 619 // Velocities
 620 void FGInterface::set_V_calibrated_kts(double vc) {
 621     v_calibrated_kts = vc;
 622 }
 623
 624 void FGInterface::set_Mach_number(double mach) {
 625     mach_number = mach;
 626 }
 627
 628 void FGInterface::set_Velocities_Local( double north,
 629                                         double east,
 630                                         double down ){
 631     v_local_v[0] = north;
 632     v_local_v[1] = east;
 633     v_local_v[2] = down;
 634 }
 635
 636 void FGInterface::set_Velocities_Wind_Body( double u,
 637                                             double v,
 638                                             double w){
 639     v_wind_body_v[0] = u;
 640     v_wind_body_v[1] = v;
 641     v_wind_body_v[2] = w;
 642 }
 643
 644 // Euler angles
 645 void FGInterface::set_Euler_Angles( double phi,
 646                                     double theta,
 647                                     double psi ) {
 648     euler_angles_v[0] = phi;
 649     euler_angles_v[1] = theta;
 650     euler_angles_v[2] = psi;
 651 }
 652
 653 // Flight Path
 654 void FGInterface::set_Climb_Rate( double roc) {
 655     climb_rate = roc;
 656 }
 657
 658 void FGInterface::set_Gamma_vert_rad( double gamma) {
 659     gamma_vert_rad = gamma;
 660 }
 661
 662 void FGInterface::set_Static_pressure(double p) { static_pressure = p; }
 663 void FGInterface::set_Static_temperature(double T) { static_temperature = T; }
 664 void FGInterface::set_Density(double rho) { density = rho; }
 665
 666 void FGInterface::set_Velocities_Local_Airmass (double wnorth,
 667                                                 double weast,
 668                                                 double wdown ) {
 669     v_local_airmass_v[0] = wnorth;
 670     v_local_airmass_v[1] = weast;
 671     v_local_airmass_v[2] = wdown;
 672 }
 673
 674
 675 void FGInterface::_busdump(void) {
 676
 677     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]);
 678     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]);
 679     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]);
 680     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]);
 681     SG_LOG(SG_FLIGHT,SG_INFO,"f_aero_v[3]: " << f_aero_v[0] << ", " << f_aero_v[1] << ", " << f_aero_v[2]);
 682     SG_LOG(SG_FLIGHT,SG_INFO,"f_engine_v[3]: " << f_engine_v[0] << ", " << f_engine_v[1] << ", " << f_engine_v[2]);
 683     SG_LOG(SG_FLIGHT,SG_INFO,"f_gear_v[3]: " << f_gear_v[0] << ", " << f_gear_v[1] << ", " << f_gear_v[2]);
 684     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]);
 685     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]);
 686     SG_LOG(SG_FLIGHT,SG_INFO,"m_aero_v[3]: " << m_aero_v[0] << ", " << m_aero_v[1] << ", " << m_aero_v[2]);
 687     SG_LOG(SG_FLIGHT,SG_INFO,"m_engine_v[3]: " << m_engine_v[0] << ", " << m_engine_v[1] << ", " << m_engine_v[2]);
 688     SG_LOG(SG_FLIGHT,SG_INFO,"m_gear_v[3]: " << m_gear_v[0] << ", " << m_gear_v[1] << ", " << m_gear_v[2]);
 689     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]);
 690     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]);
 691     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]);
 692     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]);
 693     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]);
 694     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]);
 695     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]);
 696     SG_LOG(SG_FLIGHT,SG_INFO,"v_local_v[3]: " << v_local_v[0] << ", " << v_local_v[1] << ", " << v_local_v[2]);
 697     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]);
 698     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]);
 699     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]);
 700     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]);
 701     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]);
 702     SG_LOG(SG_FLIGHT,SG_INFO,"omega_body_v[3]: " << omega_body_v[0] << ", " << omega_body_v[1] << ", " << omega_body_v[2]);
 703     SG_LOG(SG_FLIGHT,SG_INFO,"omega_local_v[3]: " << omega_local_v[0] << ", " << omega_local_v[1] << ", " << omega_local_v[2]);
 704     SG_LOG(SG_FLIGHT,SG_INFO,"omega_total_v[3]: " << omega_total_v[0] << ", " << omega_total_v[1] << ", " << omega_total_v[2]);
 705     SG_LOG(SG_FLIGHT,SG_INFO,"euler_rates_v[3]: " << euler_rates_v[0] << ", " << euler_rates_v[1] << ", " << euler_rates_v[2]);
 706     SG_LOG(SG_FLIGHT,SG_INFO,"geocentric_rates_v[3]: " << geocentric_rates_v[0] << ", " << geocentric_rates_v[1] << ", " << geocentric_rates_v[2]);
 707     SG_LOG(SG_FLIGHT,SG_INFO,"geocentric_position_v[3]: " << geocentric_position_v[0] << ", " << geocentric_position_v[1] << ", " << geocentric_position_v[2]);
 708     SG_LOG(SG_FLIGHT,SG_INFO,"geodetic_position_v[3]: " << geodetic_position_v[0] << ", " << geodetic_position_v[1] << ", " << geodetic_position_v[2]);
 709     SG_LOG(SG_FLIGHT,SG_INFO,"euler_angles_v[3]: " << euler_angles_v[0] << ", " << euler_angles_v[1] << ", " << euler_angles_v[2]);
 710     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]);
 711     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]);
 712     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]);
 713     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]);
 714
 715     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]);
 716     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]);
 717     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]);
 718
 719     SG_LOG(SG_FLIGHT,SG_INFO,"mass: " << mass );
 720     SG_LOG(SG_FLIGHT,SG_INFO,"i_xx: " << i_xx );
 721     SG_LOG(SG_FLIGHT,SG_INFO,"i_yy: " << i_yy );
 722     SG_LOG(SG_FLIGHT,SG_INFO,"i_zz: " << i_zz );
 723     SG_LOG(SG_FLIGHT,SG_INFO,"i_xz: " << i_xz );
 724     SG_LOG(SG_FLIGHT,SG_INFO,"nlf: " << nlf );
 725     SG_LOG(SG_FLIGHT,SG_INFO,"v_rel_wind: " << v_rel_wind );
 726     SG_LOG(SG_FLIGHT,SG_INFO,"v_true_kts: " << v_true_kts );
 727     SG_LOG(SG_FLIGHT,SG_INFO,"v_rel_ground: " << v_rel_ground );
 728     SG_LOG(SG_FLIGHT,SG_INFO,"v_inertial: " << v_inertial );
 729     SG_LOG(SG_FLIGHT,SG_INFO,"v_ground_speed: " << v_ground_speed );
 730     SG_LOG(SG_FLIGHT,SG_INFO,"v_equiv: " << v_equiv );
 731     SG_LOG(SG_FLIGHT,SG_INFO,"v_equiv_kts: " << v_equiv_kts );
 732     SG_LOG(SG_FLIGHT,SG_INFO,"v_calibrated: " << v_calibrated );
 733     SG_LOG(SG_FLIGHT,SG_INFO,"v_calibrated_kts: " << v_calibrated_kts );
 734     SG_LOG(SG_FLIGHT,SG_INFO,"gravity: " << gravity );
 735     SG_LOG(SG_FLIGHT,SG_INFO,"centrifugal_relief: " << centrifugal_relief );
 736     SG_LOG(SG_FLIGHT,SG_INFO,"alpha: " << alpha );
 737     SG_LOG(SG_FLIGHT,SG_INFO,"beta: " << beta );
 738     SG_LOG(SG_FLIGHT,SG_INFO,"alpha_dot: " << alpha_dot );
 739     SG_LOG(SG_FLIGHT,SG_INFO,"beta_dot: " << beta_dot );
 740     SG_LOG(SG_FLIGHT,SG_INFO,"cos_alpha: " << cos_alpha );
 741     SG_LOG(SG_FLIGHT,SG_INFO,"sin_alpha: " << sin_alpha );
 742     SG_LOG(SG_FLIGHT,SG_INFO,"cos_beta: " << cos_beta );
 743     SG_LOG(SG_FLIGHT,SG_INFO,"sin_beta: " << sin_beta );
 744     SG_LOG(SG_FLIGHT,SG_INFO,"cos_phi: " << cos_phi );
 745     SG_LOG(SG_FLIGHT,SG_INFO,"sin_phi: " << sin_phi );
 746     SG_LOG(SG_FLIGHT,SG_INFO,"cos_theta: " << cos_theta );
 747     SG_LOG(SG_FLIGHT,SG_INFO,"sin_theta: " << sin_theta );
 748     SG_LOG(SG_FLIGHT,SG_INFO,"cos_psi: " << cos_psi );
 749     SG_LOG(SG_FLIGHT,SG_INFO,"sin_psi: " << sin_psi );
 750     SG_LOG(SG_FLIGHT,SG_INFO,"gamma_vert_rad: " << gamma_vert_rad );
 751     SG_LOG(SG_FLIGHT,SG_INFO,"gamma_horiz_rad: " << gamma_horiz_rad );
 752     SG_LOG(SG_FLIGHT,SG_INFO,"sigma: " << sigma );
 753     SG_LOG(SG_FLIGHT,SG_INFO,"density: " << density );
 754     SG_LOG(SG_FLIGHT,SG_INFO,"v_sound: " << v_sound );
 755     SG_LOG(SG_FLIGHT,SG_INFO,"mach_number: " << mach_number );
 756     SG_LOG(SG_FLIGHT,SG_INFO,"static_pressure: " << static_pressure );
 757     SG_LOG(SG_FLIGHT,SG_INFO,"total_pressure: " << total_pressure );
 758     SG_LOG(SG_FLIGHT,SG_INFO,"impact_pressure: " << impact_pressure );
 759     SG_LOG(SG_FLIGHT,SG_INFO,"dynamic_pressure: " << dynamic_pressure );
 760     SG_LOG(SG_FLIGHT,SG_INFO,"static_temperature: " << static_temperature );
 761     SG_LOG(SG_FLIGHT,SG_INFO,"total_temperature: " << total_temperature );
 762     SG_LOG(SG_FLIGHT,SG_INFO,"sea_level_radius: " << sea_level_radius );
 763     SG_LOG(SG_FLIGHT,SG_INFO,"earth_position_angle: " << earth_position_angle );
 764     SG_LOG(SG_FLIGHT,SG_INFO,"runway_altitude: " << runway_altitude );
 765     SG_LOG(SG_FLIGHT,SG_INFO,"runway_latitude: " << runway_latitude );
 766     SG_LOG(SG_FLIGHT,SG_INFO,"runway_longitude: " << runway_longitude );
 767     SG_LOG(SG_FLIGHT,SG_INFO,"runway_heading: " << runway_heading );
 768     SG_LOG(SG_FLIGHT,SG_INFO,"radius_to_rwy: " << radius_to_rwy );
 769     SG_LOG(SG_FLIGHT,SG_INFO,"climb_rate: " << climb_rate );
 770     SG_LOG(SG_FLIGHT,SG_INFO,"sin_lat_geocentric: " << sin_lat_geocentric );
 771     SG_LOG(SG_FLIGHT,SG_INFO,"cos_lat_geocentric: " << cos_lat_geocentric );
 772     SG_LOG(SG_FLIGHT,SG_INFO,"sin_longitude: " << sin_longitude );
 773     SG_LOG(SG_FLIGHT,SG_INFO,"cos_longitude: " << cos_longitude );
 774     SG_LOG(SG_FLIGHT,SG_INFO,"sin_latitude: " << sin_latitude );
 775     SG_LOG(SG_FLIGHT,SG_INFO,"cos_latitude: " << cos_latitude );
 776     SG_LOG(SG_FLIGHT,SG_INFO,"altitude_agl: " << altitude_agl );
 777 }
 778
 779 bool
 780 FGInterface::prepare_ground_cache_m(double ref_time, const double pt[3],
 781                                     double rad)
 782 {
 783   return ground_cache.prepare_ground_cache(ref_time, pt, rad);
 784 }
 785
 786 bool FGInterface::prepare_ground_cache_ft(double ref_time, const double pt[3],
 787                                           double rad)
 788 {
 789   // Convert units and do the real work.
 790   sgdVec3 pt_ft;
 791   sgdScaleVec3( pt_ft, pt, SG_FEET_TO_METER );
 792   return ground_cache.prepare_ground_cache(ref_time, pt_ft, rad*SG_FEET_TO_METER);
 793 }
 794
 795 bool
 796 FGInterface::is_valid_m(double *ref_time, double pt[3], double *rad)
 797 {
 798   return ground_cache.is_valid(ref_time, pt, rad);
 799 }
 800
 801 bool FGInterface::is_valid_ft(double *ref_time, double pt[3], double *rad)
 802 {
 803   // Convert units and do the real work.
 804   bool found_ground = ground_cache.is_valid(ref_time, pt, rad);
 805   sgdScaleVec3(pt, SG_METER_TO_FEET);
 806   *rad *= SG_METER_TO_FEET;
 807   return found_ground;
 808 }
 809
 810 double
 811 FGInterface::get_cat_m(double t, const double pt[3],
 812                        double end[2][3], double vel[2][3])
 813 {
 814   return ground_cache.get_cat(t, pt, end, vel);
 815 }
 816
 817 double
 818 FGInterface::get_cat_ft(double t, const double pt[3],
 819                         double end[2][3], double vel[2][3])
 820 {
 821   // Convert units and do the real work.
 822   sgdVec3 pt_m;
 823   sgdScaleVec3( pt_m, pt, SG_FEET_TO_METER );
 824   double dist = ground_cache.get_cat(t, pt_m, end, vel);
 825   for (int k=0; k<2; ++k) {
 826     sgdScaleVec3( end[k], SG_METER_TO_FEET );
 827     sgdScaleVec3( vel[k], SG_METER_TO_FEET );
 828   }
 829   return dist*SG_METER_TO_FEET;
 830 }
 831
 832 bool
 833 FGInterface::get_agl_m(double t, const double pt[3],
 834                        double contact[3], double normal[3], double vel[3],
 835                        int *type, double *loadCapacity,
 836                        double *frictionFactor, double *agl)
 837 {
 838   return ground_cache.get_agl(t, pt, 2.0, contact, normal, vel, type,
 839                               loadCapacity, frictionFactor, agl);
 840 }
 841
 842 bool
 843 FGInterface::get_agl_ft(double t, const double pt[3],
 844                         double contact[3], double normal[3], double vel[3],
 845                         int *type, double *loadCapacity,
 846                         double *frictionFactor, double *agl)
 847 {
 848   // Convert units and do the real work.
 849   sgdVec3 pt_m;
 850   sgdScaleVec3( pt_m, pt, SG_FEET_TO_METER );
 851   bool ret = ground_cache.get_agl(t, pt_m, 2.0, contact, normal, vel,
 852                                   type, loadCapacity, frictionFactor, agl);
 853   // Convert units back ...
 854   sgdScaleVec3( contact, SG_METER_TO_FEET );
 855   sgdScaleVec3( vel, SG_METER_TO_FEET );
 856   *agl *= SG_METER_TO_FEET;
 857   // FIXME: scale the load limit to something in the english unit system.
 858   // Be careful with the DBL_MAX which is returned by default.
 859   return ret;
 860 }
 861
 862 bool
 863 FGInterface::get_agl_m(double t, const double pt[3], double max_altoff,
 864                        double contact[3], double normal[3], double vel[3],
 865                        int *type, double *loadCapacity,
 866                        double *frictionFactor, double *agl)
 867 {
 868   return ground_cache.get_agl(t, pt, max_altoff, contact, normal, vel, type,
 869                               loadCapacity, frictionFactor, agl);
 870 }
 871
 872 bool
 873 FGInterface::get_agl_ft(double t, const double pt[3], double max_altoff,
 874                         double contact[3], double normal[3], double vel[3],
 875                         int *type, double *loadCapacity,
 876                         double *frictionFactor, double *agl)
 877 {
 878   // Convert units and do the real work.
 879   sgdVec3 pt_m;
 880   sgdScaleVec3( pt_m, pt, SG_FEET_TO_METER );
 881   bool ret = ground_cache.get_agl(t, pt_m, SG_FEET_TO_METER * max_altoff,
 882                                   contact, normal, vel,
 883                                   type, loadCapacity, frictionFactor, agl);
 884   // Convert units back ...
 885   sgdScaleVec3( contact, SG_METER_TO_FEET );
 886   sgdScaleVec3( vel, SG_METER_TO_FEET );
 887   *agl *= SG_METER_TO_FEET;
 888   // FIXME: scale the load limit to something in the english unit system.
 889   // Be careful with the DBL_MAX which is returned by default.
 890   return ret;
 891 }
 892
 893
 894 double
 895 FGInterface::get_groundlevel_m(double lat, double lon, double alt)
 896 {
 897   // First compute the sea level radius,
 898   sgdVec3 pos, cpos;
 899   sgGeodToCart(lat, lon, 0, pos);
 900   double slr = sgdLengthVec3(pos);
 901   // .. then the cartesian position of the given lat/lon/alt.
 902   sgGeodToCart(lat, lon, alt, pos);
 903
 904   // FIXME: how to handle t - ref_time differences ???
 905   double ref_time, radius;
 906   // Prepare the ground cache for that position.
 907   if (!is_valid_m(&ref_time, cpos, &radius))
 908     prepare_ground_cache_m(ref_time, pos, 10);
 909   else if (radius*radius <= sgdDistanceSquaredVec3(pos, cpos))
 910     prepare_ground_cache_m(ref_time, pos, radius);
 911
 912   double contact[3], normal[3], vel[3], lc, ff, agl;
 913   int type;
 914   get_agl_m(ref_time, pos, 2.0, contact, normal, vel, &type, &lc, &ff, &agl);
 915
 916   return sgdLengthVec3(contact) - slr;
 917 }
 918
 919 bool
 920 FGInterface::caught_wire_m(double t, const double pt[4][3])
 921 {
 922   return ground_cache.caught_wire(t, pt);
 923 }
 924
 925 bool
 926 FGInterface::caught_wire_ft(double t, const double pt[4][3])
 927 {
 928   // Convert units and do the real work.
 929   double pt_m[4][3];
 930   for (int i=0; i<4; ++i)
 931     sgdScaleVec3(pt_m[i], pt[i], SG_FEET_TO_METER);
 932
 933   return ground_cache.caught_wire(t, pt_m);
 934 }
 935
 936 bool
 937 FGInterface::get_wire_ends_m(double t, double end[2][3], double vel[2][3])
 938 {
 939   return ground_cache.get_wire_ends(t, end, vel);
 940 }
 941
 942 bool
 943 FGInterface::get_wire_ends_ft(double t, double end[2][3], double vel[2][3])
 944 {
 945   // Convert units and do the real work.
 946   bool ret = ground_cache.get_wire_ends(t, end, vel);
 947   for (int k=0; k<2; ++k) {
 948     sgdScaleVec3( end[k], SG_METER_TO_FEET );
 949     sgdScaleVec3( vel[k], SG_METER_TO_FEET );
 950   }
 951   return ret;
 952 }
 953
 954 void
 955 FGInterface::release_wire(void)
 956 {
 957   ground_cache.release_wire();
 958 }
 959
 960 void fgToggleFDMdataLogging(void) {
 961   cur_fdm_state->ToggleDataLogging();
 962 }