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
  91   // If we artificially inflate ml above by a tiny amount to get the
  92   // closest integer, then subtract the integer from the original
  93   // slightly smaller value, we can get a negative remainder.
  94   // Logically this should never happen, and we definitely don't want
  95   // to carry a negative remainder over to the next iteration, so
  96   // never let the remainder go below zero.
  97   //
  98   // Note: this fixes a problem where we run 1, 3, 1, 3, 1, 3... loops
  99   // of the FDM when in fact we want to run 2, 2, 2, 2, 2...
 100   if ( remainder < 0 ) { remainder = 0; }
 101
 102   return (multiloop * speedup);
 103 }
 104
 105
 106 /**
 107  * Set default values for the state of the FDM.
 108  *
 109  * This method is invoked by the constructors.
 110  */
 111 void
 112 FGInterface::_setup ()
 113 {
 114     inited = false;
 115     bound = false;
 116
 117     init_vec( d_pilot_rp_body_v );
 118     init_vec( d_cg_rp_body_v );
 119     init_vec( f_body_total_v );
 120     init_vec( f_local_total_v );
 121     init_vec( f_aero_v );
 122     init_vec( f_engine_v );
 123     init_vec( f_gear_v );
 124     init_vec( m_total_rp_v );
 125     init_vec( m_total_cg_v );
 126     init_vec( m_aero_v );
 127     init_vec( m_engine_v );
 128     init_vec( m_gear_v );
 129     init_vec( v_dot_local_v );
 130     init_vec( v_dot_body_v );
 131     init_vec( a_cg_body_v );
 132     init_vec( a_pilot_body_v );
 133     init_vec( n_cg_body_v );
 134     init_vec( n_pilot_body_v );
 135     init_vec( omega_dot_body_v );
 136     init_vec( v_local_v );
 137     init_vec( v_local_rel_ground_v );
 138     init_vec( v_local_airmass_v );
 139     init_vec( v_local_rel_airmass_v );
 140     init_vec( v_local_gust_v );
 141     init_vec( v_wind_body_v );
 142     init_vec( omega_body_v );
 143     init_vec( omega_local_v );
 144     init_vec( omega_total_v );
 145     init_vec( euler_rates_v );
 146     init_vec( geocentric_rates_v );
 147     init_vec( geocentric_position_v );
 148     init_vec( geodetic_position_v );
 149     init_vec( euler_angles_v );
 150     init_vec( d_cg_rwy_local_v );
 151     init_vec( d_cg_rwy_rwy_v );
 152     init_vec( d_pilot_rwy_local_v );
 153     init_vec( d_pilot_rwy_rwy_v );
 154     init_vec( t_local_to_body_m[0] );
 155     init_vec( t_local_to_body_m[1] );
 156     init_vec( t_local_to_body_m[2] );
 157
 158     mass=i_xx=i_yy=i_zz=i_xz=0;
 159     nlf=0;
 160     v_rel_wind=v_true_kts=v_rel_ground=v_inertial=0;
 161     v_ground_speed=v_equiv=v_equiv_kts=0;
 162     v_calibrated=v_calibrated_kts=0;
 163     gravity=0;
 164     centrifugal_relief=0;
 165     alpha=beta=alpha_dot=beta_dot=0;
 166     cos_alpha=sin_alpha=cos_beta=sin_beta=0;
 167     cos_phi=sin_phi=cos_theta=sin_theta=cos_psi=sin_psi=0;
 168     gamma_vert_rad=gamma_horiz_rad=0;
 169     sigma=density=v_sound=mach_number=0;
 170     static_pressure=total_pressure=impact_pressure=0;
 171     dynamic_pressure=0;
 172     static_temperature=total_temperature=0;
 173     sea_level_radius=earth_position_angle=0;
 174     runway_altitude=runway_latitude=runway_longitude=0;
 175     runway_heading=0;
 176     radius_to_rwy=0;
 177     climb_rate=0;
 178     sin_lat_geocentric=cos_lat_geocentric=0;
 179     sin_latitude=cos_latitude=0;
 180     sin_longitude=cos_longitude=0;
 181     altitude_agl=0;
 182 }
 183
 184 void
 185 FGInterface::init () {}
 186
 187 /**
 188  * Initialize the state of the FDM.
 189  *
 190  * Subclasses of FGInterface may do their own, additional initialization,
 191  * but there is some that is common to all.  Normally, they should call
 192  * this before they begin their own init to make sure the basic structures
 193  * are set up properly.
 194  */
 195 void
 196 FGInterface::common_init ()
 197 {
 198     SG_LOG( SG_FLIGHT, SG_INFO, "Start common FDM init" );
 199
 200     set_inited( true );
 201
 202 //     stamp();
 203 //     set_remainder( 0 );
 204
 205     // Set initial position
 206     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing position..." );
 207     double lon = fgGetDouble("/sim/presets/longitude-deg")
 208       * SGD_DEGREES_TO_RADIANS;
 209     double lat = fgGetDouble("/sim/presets/latitude-deg")
 210       * SGD_DEGREES_TO_RADIANS;
 211     double alt_ft = fgGetDouble("/sim/presets/altitude-ft");
 212     double alt_m = alt_ft * SG_FEET_TO_METER;
 213     set_Longitude( lon );
 214     set_Latitude( lat );
 215     SG_LOG( SG_FLIGHT, SG_INFO, "Checking for lon = "
 216             << lon*SGD_RADIANS_TO_DEGREES << "deg, lat = "
 217             << lat*SGD_RADIANS_TO_DEGREES << "deg, alt = "
 218             << alt_ft << "ft");
 219
 220     double ground_elev_m = get_groundlevel_m(lat, lon, alt_m);
 221     double ground_elev_ft = ground_elev_m * SG_METER_TO_FEET;
 222     _set_Runway_altitude ( ground_elev_ft );
 223     if ( fgGetBool("/sim/presets/onground") || alt_ft < ground_elev_ft ) {
 224         fgSetDouble("/position/altitude-ft", ground_elev_ft + 0.1);
 225         set_Altitude( ground_elev_ft + 0.1);
 226     } else {
 227         set_Altitude( alt_ft );
 228     }
 229
 230     // Set ground elevation
 231     SG_LOG( SG_FLIGHT, SG_INFO,
 232             "...initializing ground elevation to " << ground_elev_ft
 233             << "ft..." );
 234
 235     // Set sea-level radius
 236     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing sea-level radius..." );
 237     SG_LOG( SG_FLIGHT, SG_INFO, " lat = "
 238             << fgGetDouble("/sim/presets/latitude-deg")
 239             << " alt = " << get_Altitude() );
 240     double sea_level_radius_meters;
 241     double lat_geoc;
 242     sgGeodToGeoc( fgGetDouble("/sim/presets/latitude-deg")
 243                     * SGD_DEGREES_TO_RADIANS,
 244                   get_Altitude() * SG_FEET_TO_METER,
 245                   &sea_level_radius_meters, &lat_geoc );
 246     _set_Sea_level_radius( sea_level_radius_meters * SG_METER_TO_FEET );
 247
 248     // Set initial velocities
 249     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing velocities..." );
 250     if ( !fgHasNode("/sim/presets/speed-set") ) {
 251         set_V_calibrated_kts(0.0);
 252     } else {
 253         const string speedset = fgGetString("/sim/presets/speed-set");
 254         if ( speedset == "knots" || speedset == "KNOTS" ) {
 255             set_V_calibrated_kts( fgGetDouble("/sim/presets/airspeed-kt") );
 256         } else if ( speedset == "mach" || speedset == "MACH" ) {
 257             set_Mach_number( fgGetDouble("/sim/presets/mach") );
 258         } else if ( speedset == "UVW" || speedset == "uvw" ) {
 259             set_Velocities_Wind_Body(
 260                                      fgGetDouble("/sim/presets/uBody-fps"),
 261                                      fgGetDouble("/sim/presets/vBody-fps"),
 262                                      fgGetDouble("/sim/presets/wBody-fps") );
 263         } else if ( speedset == "NED" || speedset == "ned" ) {
 264             set_Velocities_Local(
 265                                  fgGetDouble("/sim/presets/speed-north-fps"),
 266                                  fgGetDouble("/sim/presets/speed-east-fps"),
 267                                  fgGetDouble("/sim/presets/speed-down-fps") );
 268         } else {
 269             SG_LOG( SG_FLIGHT, SG_ALERT,
 270                     "Unrecognized value for /sim/presets/speed-set: "
 271                     << speedset);
 272             set_V_calibrated_kts( 0.0 );
 273         }
 274     }
 275
 276     // Set initial Euler angles
 277     SG_LOG( SG_FLIGHT, SG_INFO, "...initializing Euler angles..." );
 278     set_Euler_Angles( fgGetDouble("/sim/presets/roll-deg")
 279                         * SGD_DEGREES_TO_RADIANS,
 280                       fgGetDouble("/sim/presets/pitch-deg")
 281                         * SGD_DEGREES_TO_RADIANS,
 282                       fgGetDouble("/sim/presets/heading-deg")
 283                         * SGD_DEGREES_TO_RADIANS );
 284
 285     SG_LOG( SG_FLIGHT, SG_INFO, "End common FDM init" );
 286 }
 287
 288
 289 /**
 290  * Bind getters and setters to properties.
 291  *
 292  * The bind() method will be invoked after init().  Note that unlike
 293  * the usual implementations of FGSubsystem::bind(), this method does
 294  * not automatically pick up existing values for the properties at
 295  * bind time; instead, all values are set explicitly in the init()
 296  * method.
 297  */
 298 void
 299 FGInterface::bind ()
 300 {
 301   bound = true;
 302
 303                                 // Time management (read-only)
 304 //   fgTie("/fdm/time/delta_t", this,
 305 //         &FGInterface::get_delta_t); // read-only
 306 //   fgTie("/fdm/time/elapsed", this,
 307 //         &FGInterface::get_elapsed); // read-only
 308 //   fgTie("/fdm/time/remainder", this,
 309 //         &FGInterface::get_remainder); // read-only
 310 //   fgTie("/fdm/time/multi_loop", this,
 311 //         &FGInterface::get_multi_loop); // read-only
 312
 313                         // Aircraft position
 314   fgTie("/position/latitude-deg", this,
 315         &FGInterface::get_Latitude_deg,
 316         &FGInterface::set_Latitude_deg,
 317         false);
 318   fgSetArchivable("/position/latitude-deg");
 319   fgTie("/position/longitude-deg", this,
 320         &FGInterface::get_Longitude_deg,
 321         &FGInterface::set_Longitude_deg,
 322         false);
 323   fgSetArchivable("/position/longitude-deg");
 324   fgTie("/position/altitude-ft", this,
 325         &FGInterface::get_Altitude,
 326         &FGInterface::set_Altitude,
 327         false);
 328   fgSetArchivable("/position/altitude-ft");
 329   fgTie("/position/altitude-agl-ft", this,
 330         &FGInterface::get_Altitude_AGL); // read-only
 331   fgSetArchivable("/position/ground-elev-ft");
 332   fgTie("/position/ground-elev-ft", this,
 333         &FGInterface::get_Runway_altitude); // read-only
 334   fgSetArchivable("/position/ground-elev-m");
 335   fgTie("/position/ground-elev-m", this,
 336         &FGInterface::get_Runway_altitude_m); // read-only
 337   fgTie("/environment/ground-elevation-m", this,
 338         &FGInterface::get_Runway_altitude_m); // read-only
 339   fgSetArchivable("/position/sea-level-radius-ft");
 340   fgTie("/position/sea-level-radius-ft", this,
 341         &FGInterface::get_Sea_level_radius); // read-only
 342
 343                                 // Orientation
 344   fgTie("/orientation/roll-deg", this,
 345         &FGInterface::get_Phi_deg,
 346         &FGInterface::set_Phi_deg);
 347   fgSetArchivable("/orientation/roll-deg");
 348   fgTie("/orientation/pitch-deg", this,
 349         &FGInterface::get_Theta_deg,
 350         &FGInterface::set_Theta_deg);
 351   fgSetArchivable("/orientation/pitch-deg");
 352   fgTie("/orientation/heading-deg", this,
 353         &FGInterface::get_Psi_deg,
 354         &FGInterface::set_Psi_deg);
 355   fgSetArchivable("/orientation/heading-deg");
 356
 357   // Body-axis "euler rates" (rotation speed, but in a funny
 358   // representation).
 359   fgTie("/orientation/roll-rate-degps", this,
 360         &FGInterface::get_Phi_dot_degps);
 361   fgTie("/orientation/pitch-rate-degps", this,
 362         &FGInterface::get_Theta_dot_degps);
 363   fgTie("/orientation/yaw-rate-degps", this,
 364         &FGInterface::get_Psi_dot_degps);
 365
 366                                 // Calibrated airspeed
 367   fgTie("/velocities/airspeed-kt", this,
 368         &FGInterface::get_V_calibrated_kts,
 369         &FGInterface::set_V_calibrated_kts,
 370         false);
 371
 372                                 // Mach number
 373   fgTie("/velocities/mach", this,
 374         &FGInterface::get_Mach_number,
 375         &FGInterface::set_Mach_number,
 376         false);
 377
 378                                 // Local velocities
 379 //   fgTie("/velocities/speed-north-fps", this,
 380 //      &FGInterface::get_V_north,
 381 //      &FGInterface::set_V_north);
 382 //   fgSetArchivable("/velocities/speed-north-fps");
 383 //   fgTie("/velocities/speed-east-fps", this,
 384 //      &FGInterface::get_V_east,
 385 //      &FGInterface::set_V_east);
 386 //   fgSetArchivable("/velocities/speed-east-fps");
 387 //   fgTie("/velocities/speed-down-fps", this,
 388 //      &FGInterface::get_V_down,
 389 //      &FGInterface::set_V_down);
 390 //   fgSetArchivable("/velocities/speed-down-fps");
 391                                 // FIXME: Temporarily read-only, until the
 392                                 // incompatibilities between JSBSim and
 393                                 // LaRCSim are fixed (LaRCSim adds the
 394                                 // earth's rotation to the east velocity).
 395   fgTie("/velocities/speed-north-fps", this,
 396         &FGInterface::get_V_north);
 397   fgTie("/velocities/speed-east-fps", this,
 398         &FGInterface::get_V_east);
 399   fgTie("/velocities/speed-down-fps", this,
 400         &FGInterface::get_V_down);
 401
 402                                 // Relative wind
 403                                 // FIXME: temporarily archivable, until
 404                                 // the NED problem is fixed.
 405   fgTie("/velocities/uBody-fps", this,
 406         &FGInterface::get_uBody,
 407         &FGInterface::set_uBody,
 408         false);
 409   fgSetArchivable("/velocities/uBody-fps");
 410   fgTie("/velocities/vBody-fps", this,
 411         &FGInterface::get_vBody,
 412         &FGInterface::set_vBody,
 413         false);
 414   fgSetArchivable("/velocities/vBody-fps");
 415   fgTie("/velocities/wBody-fps", this,
 416         &FGInterface::get_wBody,
 417         &FGInterface::set_wBody,
 418         false);
 419   fgSetArchivable("/velocities/wBody-fps");
 420
 421                                 // Climb and slip (read-only)
 422   fgTie("/velocities/vertical-speed-fps", this,
 423         &FGInterface::get_Climb_Rate,
 424   &FGInterface::set_Climb_Rate );
 425   fgTie("/velocities/glideslope", this,
 426   &FGInterface::get_Gamma_vert_rad,
 427   &FGInterface::set_Gamma_vert_rad );
 428   fgTie("/orientation/side-slip-rad", this,
 429         &FGInterface::get_Beta); // read-only
 430   fgTie("/orientation/side-slip-deg", this,
 431   &FGInterface::get_Beta_deg); // read-only
 432   fgTie("/orientation/alpha-deg", this,
 433   &FGInterface::get_Alpha_deg); // read-only
 434   fgTie("/accelerations/nlf", this,
 435   &FGInterface::get_Nlf); // read-only
 436
 437                                 // NED accelerations
 438   fgTie("/accelerations/ned/north-accel-fps_sec",
 439         this, &FGInterface::get_V_dot_north);
 440   fgTie("/accelerations/ned/east-accel-fps_sec",
 441         this, &FGInterface::get_V_dot_east);
 442   fgTie("/accelerations/ned/down-accel-fps_sec",
 443         this, &FGInterface::get_V_dot_down);
 444
 445                                 // Pilot accelerations
 446   fgTie("/accelerations/pilot/x-accel-fps_sec",
 447         this, &FGInterface::get_A_X_pilot);
 448   fgTie("/accelerations/pilot/y-accel-fps_sec",
 449         this, &FGInterface::get_A_Y_pilot);
 450   fgTie("/accelerations/pilot/z-accel-fps_sec",
 451         this, &FGInterface::get_A_Z_pilot);
 452
 453 }
 454
 455
 456 /**
 457  * Unbind any properties bound to this FDM.
 458  *
 459  * This method allows the FDM to release properties so that a new
 460  * FDM can bind them instead.
 461  */
 462 void
 463 FGInterface::unbind ()
 464 {
 465   bound = false;
 466
 467   // fgUntie("/fdm/time/delta_t");
 468   // fgUntie("/fdm/time/elapsed");
 469   // fgUntie("/fdm/time/remainder");
 470   // fgUntie("/fdm/time/multi_loop");
 471   fgUntie("/position/latitude-deg");
 472   fgUntie("/position/longitude-deg");
 473   fgUntie("/position/altitude-ft");
 474   fgUntie("/position/altitude-agl-ft");
 475   fgUntie("/position/ground-elev-ft");
 476   fgUntie("/position/ground-elev-m");
 477   fgUntie("/environment/ground-elevation-m");
 478   fgUntie("/position/sea-level-radius-ft");
 479   fgUntie("/orientation/roll-deg");
 480   fgUntie("/orientation/pitch-deg");
 481   fgUntie("/orientation/heading-deg");
 482   fgUntie("/orientation/roll-rate-degps");
 483   fgUntie("/orientation/pitch-rate-degps");
 484   fgUntie("/orientation/yaw-rate-degps");
 485   fgUntie("/orientation/side-slip-rad");
 486   fgUntie("/orientation/side-slip-deg");
 487   fgUntie("/orientation/alpha-deg");
 488   fgUntie("/velocities/airspeed-kt");
 489   fgUntie("/velocities/mach");
 490   fgUntie("/velocities/speed-north-fps");
 491   fgUntie("/velocities/speed-east-fps");
 492   fgUntie("/velocities/speed-down-fps");
 493   fgUntie("/velocities/uBody-fps");
 494   fgUntie("/velocities/vBody-fps");
 495   fgUntie("/velocities/wBody-fps");
 496   fgUntie("/velocities/vertical-speed-fps");
 497   fgUntie("/velocities/glideslope");
 498   fgUntie("/accelerations/nlf");
 499   fgUntie("/accelerations/pilot/x-accel-fps_sec");
 500   fgUntie("/accelerations/pilot/y-accel-fps_sec");
 501   fgUntie("/accelerations/pilot/z-accel-fps_sec");
 502   fgUntie("/accelerations/ned/north-accel-fps_sec");
 503   fgUntie("/accelerations/ned/east-accel-fps_sec");
 504   fgUntie("/accelerations/ned/down-accel-fps_sec");
 505 }
 506
 507 /**
 508  * Update the state of the FDM (i.e. run the equations of motion).
 509  */
 510 void
 511 FGInterface::update (double dt)
 512 {
 513     SG_LOG(SG_FLIGHT, SG_ALERT, "dummy update() ... SHOULDN'T BE CALLED!");
 514 }
 515
 516
 517 void FGInterface::_updateGeodeticPosition( double lat, double lon, double alt )
 518 {
 519     double lat_geoc, sl_radius;
 520
 521     // cout << "starting sea level rad = " << get_Sea_level_radius() << endl;
 522
 523     sgGeodToGeoc( lat, alt * SG_FEET_TO_METER, &sl_radius, &lat_geoc );
 524
 525     SG_LOG( SG_FLIGHT, SG_DEBUG, "lon = " << lon
 526             << " lat_geod = " << lat
 527             << " lat_geoc = " << lat_geoc
 528             << " alt = " << alt
 529             << " sl_radius = " << sl_radius * SG_METER_TO_FEET
 530             << " Equator = " << SG_EQUATORIAL_RADIUS_FT );
 531
 532     _set_Geocentric_Position( lat_geoc, lon,
 533                               sl_radius * SG_METER_TO_FEET + alt );
 534
 535     _set_Geodetic_Position( lat, lon, alt );
 536
 537     _set_Sea_level_radius( sl_radius * SG_METER_TO_FEET );
 538     _update_ground_elev_at_pos();
 539
 540     _set_sin_lat_geocentric( lat_geoc );
 541     _set_cos_lat_geocentric( lat_geoc );
 542
 543     _set_sin_cos_longitude( lon );
 544
 545     _set_sin_cos_latitude( lat );
 546 }
 547
 548
 549 void FGInterface::_updateGeocentricPosition( double lat_geoc, double lon,
 550                                              double alt )
 551 {
 552     double lat_geod, tmp_alt, sl_radius1, sl_radius2, tmp_lat_geoc;
 553
 554     // cout << "starting sea level rad = " << get_Sea_level_radius() << endl;
 555
 556     sgGeocToGeod( lat_geoc, ( get_Sea_level_radius() + alt ) * SG_FEET_TO_METER,
 557                   &lat_geod, &tmp_alt, &sl_radius1 );
 558     sgGeodToGeoc( lat_geod, alt * SG_FEET_TO_METER, &sl_radius2, &tmp_lat_geoc );
 559
 560     SG_LOG( SG_FLIGHT, SG_DEBUG, "lon = " << lon
 561             << " lat_geod = " << lat_geod
 562             << " lat_geoc = " << lat_geoc
 563             << " alt = " << alt
 564             << " tmp_alt = " << tmp_alt * SG_METER_TO_FEET
 565             << " sl_radius1 = " << sl_radius1 * SG_METER_TO_FEET
 566             << " sl_radius2 = " << sl_radius2 * SG_METER_TO_FEET
 567             << " Equator = " << SG_EQUATORIAL_RADIUS_FT );
 568
 569     _set_Geocentric_Position( lat_geoc, lon,
 570                               sl_radius2 * SG_METER_TO_FEET + alt );
 571
 572     _set_Geodetic_Position( lat_geod, lon, alt );
 573
 574     _set_Sea_level_radius( sl_radius2 * SG_METER_TO_FEET );
 575     _update_ground_elev_at_pos();
 576
 577     _set_sin_lat_geocentric( lat_geoc );
 578     _set_cos_lat_geocentric( lat_geoc );
 579
 580     _set_sin_cos_longitude( lon );
 581
 582     _set_sin_cos_latitude( lat_geod );
 583 }
 584
 585 void FGInterface::_update_ground_elev_at_pos( void ) {
 586     double lat = get_Latitude();
 587     double lon = get_Longitude();
 588     double alt_m = get_Altitude()*SG_FEET_TO_METER;
 589     double groundlevel_m = get_groundlevel_m(lat, lon, alt_m);
 590     _set_Runway_altitude( groundlevel_m * SG_METER_TO_FEET );
 591 }
 592
 593 // Extrapolate fdm based on time_offset (in usec)
 594 void FGInterface::extrapolate( int time_offset ) {
 595     double dt = time_offset / 1000000.0;
 596
 597     // -dw- metrowerks complains about ambiguous access, not critical
 598     // to keep this ;)
 599 #ifndef __MWERKS__
 600     SG_LOG(SG_FLIGHT, SG_INFO, "extrapolating FDM by dt = " << dt);
 601 #endif
 602
 603     double lat = geodetic_position_v[0] + geocentric_rates_v[0] * dt;
 604     double lat_geoc = geocentric_position_v[0] + geocentric_rates_v[0] * dt;
 605
 606     double lon = geodetic_position_v[1] + geocentric_rates_v[1] * dt;
 607     double lon_geoc = geocentric_position_v[1] + geocentric_rates_v[1] * dt;
 608
 609     double alt = geodetic_position_v[2] + geocentric_rates_v[2] * dt;
 610     double radius = geocentric_position_v[2] + geocentric_rates_v[2] * dt;
 611
 612     geodetic_position_v[0] = lat;
 613     geocentric_position_v[0] = lat_geoc;
 614
 615     geodetic_position_v[1] = lon;
 616     geocentric_position_v[1] = lon_geoc;
 617
 618     geodetic_position_v[2] = alt;
 619     geocentric_position_v[2] = radius;
 620 }
 621
 622 // Positions
 623 void FGInterface::set_Latitude(double lat) {
 624     geodetic_position_v[0] = lat;
 625 }
 626
 627 void FGInterface::set_Longitude(double lon) {
 628     geodetic_position_v[1] = lon;
 629 }
 630
 631 void FGInterface::set_Altitude(double alt) {
 632     geodetic_position_v[2] = alt;
 633 }
 634
 635 void FGInterface::set_AltitudeAGL(double altagl) {
 636     altitude_agl=altagl;
 637 }
 638
 639 // Velocities
 640 void FGInterface::set_V_calibrated_kts(double vc) {
 641     v_calibrated_kts = vc;
 642 }
 643
 644 void FGInterface::set_Mach_number(double mach) {
 645     mach_number = mach;
 646 }
 647
 648 void FGInterface::set_Velocities_Local( double north,
 649                                         double east,
 650                                         double down ){
 651     v_local_v[0] = north;
 652     v_local_v[1] = east;
 653     v_local_v[2] = down;
 654 }
 655
 656 void FGInterface::set_Velocities_Wind_Body( double u,
 657                                             double v,
 658                                             double w){
 659     v_wind_body_v[0] = u;
 660     v_wind_body_v[1] = v;
 661     v_wind_body_v[2] = w;
 662 }
 663
 664 // Euler angles
 665 void FGInterface::set_Euler_Angles( double phi,
 666                                     double theta,
 667                                     double psi ) {
 668     euler_angles_v[0] = phi;
 669     euler_angles_v[1] = theta;
 670     euler_angles_v[2] = psi;
 671 }
 672
 673 // Flight Path
 674 void FGInterface::set_Climb_Rate( double roc) {
 675     climb_rate = roc;
 676 }
 677
 678 void FGInterface::set_Gamma_vert_rad( double gamma) {
 679     gamma_vert_rad = gamma;
 680 }
 681
 682 void FGInterface::set_Static_pressure(double p) { static_pressure = p; }
 683 void FGInterface::set_Static_temperature(double T) { static_temperature = T; }
 684 void FGInterface::set_Density(double rho) { density = rho; }
 685
 686 void FGInterface::set_Velocities_Local_Airmass (double wnorth,
 687                                                 double weast,
 688                                                 double wdown ) {
 689     v_local_airmass_v[0] = wnorth;
 690     v_local_airmass_v[1] = weast;
 691     v_local_airmass_v[2] = wdown;
 692 }
 693
 694
 695 void FGInterface::_busdump(void) {
 696
 697     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]);
 698     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]);
 699     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]);
 700     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]);
 701     SG_LOG(SG_FLIGHT,SG_INFO,"f_aero_v[3]: " << f_aero_v[0] << ", " << f_aero_v[1] << ", " << f_aero_v[2]);
 702     SG_LOG(SG_FLIGHT,SG_INFO,"f_engine_v[3]: " << f_engine_v[0] << ", " << f_engine_v[1] << ", " << f_engine_v[2]);
 703     SG_LOG(SG_FLIGHT,SG_INFO,"f_gear_v[3]: " << f_gear_v[0] << ", " << f_gear_v[1] << ", " << f_gear_v[2]);
 704     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]);
 705     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]);
 706     SG_LOG(SG_FLIGHT,SG_INFO,"m_aero_v[3]: " << m_aero_v[0] << ", " << m_aero_v[1] << ", " << m_aero_v[2]);
 707     SG_LOG(SG_FLIGHT,SG_INFO,"m_engine_v[3]: " << m_engine_v[0] << ", " << m_engine_v[1] << ", " << m_engine_v[2]);
 708     SG_LOG(SG_FLIGHT,SG_INFO,"m_gear_v[3]: " << m_gear_v[0] << ", " << m_gear_v[1] << ", " << m_gear_v[2]);
 709     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]);
 710     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]);
 711     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]);
 712     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]);
 713     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]);
 714     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]);
 715     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]);
 716     SG_LOG(SG_FLIGHT,SG_INFO,"v_local_v[3]: " << v_local_v[0] << ", " << v_local_v[1] << ", " << v_local_v[2]);
 717     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]);
 718     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]);
 719     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]);
 720     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]);
 721     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]);
 722     SG_LOG(SG_FLIGHT,SG_INFO,"omega_body_v[3]: " << omega_body_v[0] << ", " << omega_body_v[1] << ", " << omega_body_v[2]);
 723     SG_LOG(SG_FLIGHT,SG_INFO,"omega_local_v[3]: " << omega_local_v[0] << ", " << omega_local_v[1] << ", " << omega_local_v[2]);
 724     SG_LOG(SG_FLIGHT,SG_INFO,"omega_total_v[3]: " << omega_total_v[0] << ", " << omega_total_v[1] << ", " << omega_total_v[2]);
 725     SG_LOG(SG_FLIGHT,SG_INFO,"euler_rates_v[3]: " << euler_rates_v[0] << ", " << euler_rates_v[1] << ", " << euler_rates_v[2]);
 726     SG_LOG(SG_FLIGHT,SG_INFO,"geocentric_rates_v[3]: " << geocentric_rates_v[0] << ", " << geocentric_rates_v[1] << ", " << geocentric_rates_v[2]);
 727     SG_LOG(SG_FLIGHT,SG_INFO,"geocentric_position_v[3]: " << geocentric_position_v[0] << ", " << geocentric_position_v[1] << ", " << geocentric_position_v[2]);
 728     SG_LOG(SG_FLIGHT,SG_INFO,"geodetic_position_v[3]: " << geodetic_position_v[0] << ", " << geodetic_position_v[1] << ", " << geodetic_position_v[2]);
 729     SG_LOG(SG_FLIGHT,SG_INFO,"euler_angles_v[3]: " << euler_angles_v[0] << ", " << euler_angles_v[1] << ", " << euler_angles_v[2]);
 730     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]);
 731     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]);
 732     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]);
 733     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]);
 734
 735     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]);
 736     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]);
 737     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]);
 738
 739     SG_LOG(SG_FLIGHT,SG_INFO,"mass: " << mass );
 740     SG_LOG(SG_FLIGHT,SG_INFO,"i_xx: " << i_xx );
 741     SG_LOG(SG_FLIGHT,SG_INFO,"i_yy: " << i_yy );
 742     SG_LOG(SG_FLIGHT,SG_INFO,"i_zz: " << i_zz );
 743     SG_LOG(SG_FLIGHT,SG_INFO,"i_xz: " << i_xz );
 744     SG_LOG(SG_FLIGHT,SG_INFO,"nlf: " << nlf );
 745     SG_LOG(SG_FLIGHT,SG_INFO,"v_rel_wind: " << v_rel_wind );
 746     SG_LOG(SG_FLIGHT,SG_INFO,"v_true_kts: " << v_true_kts );
 747     SG_LOG(SG_FLIGHT,SG_INFO,"v_rel_ground: " << v_rel_ground );
 748     SG_LOG(SG_FLIGHT,SG_INFO,"v_inertial: " << v_inertial );
 749     SG_LOG(SG_FLIGHT,SG_INFO,"v_ground_speed: " << v_ground_speed );
 750     SG_LOG(SG_FLIGHT,SG_INFO,"v_equiv: " << v_equiv );
 751     SG_LOG(SG_FLIGHT,SG_INFO,"v_equiv_kts: " << v_equiv_kts );
 752     SG_LOG(SG_FLIGHT,SG_INFO,"v_calibrated: " << v_calibrated );
 753     SG_LOG(SG_FLIGHT,SG_INFO,"v_calibrated_kts: " << v_calibrated_kts );
 754     SG_LOG(SG_FLIGHT,SG_INFO,"gravity: " << gravity );
 755     SG_LOG(SG_FLIGHT,SG_INFO,"centrifugal_relief: " << centrifugal_relief );
 756     SG_LOG(SG_FLIGHT,SG_INFO,"alpha: " << alpha );
 757     SG_LOG(SG_FLIGHT,SG_INFO,"beta: " << beta );
 758     SG_LOG(SG_FLIGHT,SG_INFO,"alpha_dot: " << alpha_dot );
 759     SG_LOG(SG_FLIGHT,SG_INFO,"beta_dot: " << beta_dot );
 760     SG_LOG(SG_FLIGHT,SG_INFO,"cos_alpha: " << cos_alpha );
 761     SG_LOG(SG_FLIGHT,SG_INFO,"sin_alpha: " << sin_alpha );
 762     SG_LOG(SG_FLIGHT,SG_INFO,"cos_beta: " << cos_beta );
 763     SG_LOG(SG_FLIGHT,SG_INFO,"sin_beta: " << sin_beta );
 764     SG_LOG(SG_FLIGHT,SG_INFO,"cos_phi: " << cos_phi );
 765     SG_LOG(SG_FLIGHT,SG_INFO,"sin_phi: " << sin_phi );
 766     SG_LOG(SG_FLIGHT,SG_INFO,"cos_theta: " << cos_theta );
 767     SG_LOG(SG_FLIGHT,SG_INFO,"sin_theta: " << sin_theta );
 768     SG_LOG(SG_FLIGHT,SG_INFO,"cos_psi: " << cos_psi );
 769     SG_LOG(SG_FLIGHT,SG_INFO,"sin_psi: " << sin_psi );
 770     SG_LOG(SG_FLIGHT,SG_INFO,"gamma_vert_rad: " << gamma_vert_rad );
 771     SG_LOG(SG_FLIGHT,SG_INFO,"gamma_horiz_rad: " << gamma_horiz_rad );
 772     SG_LOG(SG_FLIGHT,SG_INFO,"sigma: " << sigma );
 773     SG_LOG(SG_FLIGHT,SG_INFO,"density: " << density );
 774     SG_LOG(SG_FLIGHT,SG_INFO,"v_sound: " << v_sound );
 775     SG_LOG(SG_FLIGHT,SG_INFO,"mach_number: " << mach_number );
 776     SG_LOG(SG_FLIGHT,SG_INFO,"static_pressure: " << static_pressure );
 777     SG_LOG(SG_FLIGHT,SG_INFO,"total_pressure: " << total_pressure );
 778     SG_LOG(SG_FLIGHT,SG_INFO,"impact_pressure: " << impact_pressure );
 779     SG_LOG(SG_FLIGHT,SG_INFO,"dynamic_pressure: " << dynamic_pressure );
 780     SG_LOG(SG_FLIGHT,SG_INFO,"static_temperature: " << static_temperature );
 781     SG_LOG(SG_FLIGHT,SG_INFO,"total_temperature: " << total_temperature );
 782     SG_LOG(SG_FLIGHT,SG_INFO,"sea_level_radius: " << sea_level_radius );
 783     SG_LOG(SG_FLIGHT,SG_INFO,"earth_position_angle: " << earth_position_angle );
 784     SG_LOG(SG_FLIGHT,SG_INFO,"runway_altitude: " << runway_altitude );
 785     SG_LOG(SG_FLIGHT,SG_INFO,"runway_latitude: " << runway_latitude );
 786     SG_LOG(SG_FLIGHT,SG_INFO,"runway_longitude: " << runway_longitude );
 787     SG_LOG(SG_FLIGHT,SG_INFO,"runway_heading: " << runway_heading );
 788     SG_LOG(SG_FLIGHT,SG_INFO,"radius_to_rwy: " << radius_to_rwy );
 789     SG_LOG(SG_FLIGHT,SG_INFO,"climb_rate: " << climb_rate );
 790     SG_LOG(SG_FLIGHT,SG_INFO,"sin_lat_geocentric: " << sin_lat_geocentric );
 791     SG_LOG(SG_FLIGHT,SG_INFO,"cos_lat_geocentric: " << cos_lat_geocentric );
 792     SG_LOG(SG_FLIGHT,SG_INFO,"sin_longitude: " << sin_longitude );
 793     SG_LOG(SG_FLIGHT,SG_INFO,"cos_longitude: " << cos_longitude );
 794     SG_LOG(SG_FLIGHT,SG_INFO,"sin_latitude: " << sin_latitude );
 795     SG_LOG(SG_FLIGHT,SG_INFO,"cos_latitude: " << cos_latitude );
 796     SG_LOG(SG_FLIGHT,SG_INFO,"altitude_agl: " << altitude_agl );
 797 }
 798
 799 bool
 800 FGInterface::prepare_ground_cache_m(double ref_time, const double pt[3],
 801                                     double rad)
 802 {
 803   return ground_cache.prepare_ground_cache(ref_time, SGVec3d(pt), rad);
 804 }
 805
 806 bool FGInterface::prepare_ground_cache_ft(double ref_time, const double pt[3],
 807                                           double rad)
 808 {
 809   // Convert units and do the real work.
 810   SGVec3d pt_ft = SG_FEET_TO_METER*SGVec3d(pt);
 811   return ground_cache.prepare_ground_cache(ref_time, pt_ft, rad*SG_FEET_TO_METER);
 812 }
 813
 814 bool
 815 FGInterface::is_valid_m(double *ref_time, double pt[3], double *rad)
 816 {
 817   SGVec3d _pt;
 818   bool valid = ground_cache.is_valid(*ref_time, _pt, *rad);
 819   sgdCopyVec3(pt, _pt.data());
 820   return valid;
 821 }
 822
 823 bool FGInterface::is_valid_ft(double *ref_time, double pt[3], double *rad)
 824 {
 825   // Convert units and do the real work.
 826   SGVec3d _pt;
 827   bool found_ground = ground_cache.is_valid(*ref_time, _pt, *rad);
 828   sgdScaleVec3(pt, _pt.data(), SG_METER_TO_FEET);
 829   *rad *= SG_METER_TO_FEET;
 830   return found_ground;
 831 }
 832
 833 double
 834 FGInterface::get_cat_m(double t, const double pt[3],
 835                        double end[2][3], double vel[2][3])
 836 {
 837   SGVec3d _end[2], _vel[2];
 838   double dist = ground_cache.get_cat(t, SGVec3d(pt), _end, _vel);
 839   for (int k=0; k<2; ++k) {
 840     sgdCopyVec3( end[k], _end[k].data() );
 841     sgdCopyVec3( vel[k], _vel[k].data() );
 842   }
 843   return dist;
 844 }
 845
 846 double
 847 FGInterface::get_cat_ft(double t, const double pt[3],
 848                         double end[2][3], double vel[2][3])
 849 {
 850   // Convert units and do the real work.
 851   SGVec3d pt_m = SG_FEET_TO_METER*SGVec3d(pt);
 852   SGVec3d _end[2], _vel[2];
 853   double dist = ground_cache.get_cat(t, pt_m, _end, _vel);
 854   for (int k=0; k<2; ++k) {
 855     sgdScaleVec3( end[k], _end[k].data(), SG_METER_TO_FEET );
 856     sgdScaleVec3( vel[k], _vel[k].data(), SG_METER_TO_FEET );
 857   }
 858   return dist*SG_METER_TO_FEET;
 859 }
 860
 861 // Legacy interface just kept because of JSBSim
 862 bool
 863 FGInterface::get_agl_m(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   const SGMaterial* material;
 869   SGVec3d _contact, _normal, _vel;
 870   bool ret = ground_cache.get_agl(t, SGVec3d(pt), 2.0, _contact, _normal,
 871                                   _vel, type, &material, agl);
 872   sgdCopyVec3(contact, _contact.data());
 873   sgdCopyVec3(normal, _normal.data());
 874   sgdCopyVec3(vel, _vel.data());
 875   if (material) {
 876     *loadCapacity = material->get_load_resistence();
 877     *frictionFactor = material->get_friction_factor();
 878
 879   } else {
 880     *loadCapacity = DBL_MAX;
 881     *frictionFactor = 1.0;
 882   }
 883   return ret;
 884 }
 885
 886 bool
 887 FGInterface::get_agl_m(double t, const double pt[3],
 888                        double contact[3], double normal[3], double vel[3],
 889                        int *type, const SGMaterial **material, double *agl)
 890 {
 891   SGVec3d _contact, _normal, _vel;
 892   bool ret = ground_cache.get_agl(t, SGVec3d(pt), 2.0, _contact, _normal,
 893                                   _vel, type, material, agl);
 894   sgdCopyVec3(contact, _contact.data());
 895   sgdCopyVec3(normal, _normal.data());
 896   sgdCopyVec3(vel, _vel.data());
 897   return ret;
 898 }
 899
 900 // Legacy interface just kept because of JSBSim
 901 bool
 902 FGInterface::get_agl_ft(double t, const double pt[3],
 903                         double contact[3], double normal[3], double vel[3],
 904                         int *type, double *loadCapacity,
 905                         double *frictionFactor, double *agl)
 906 {
 907   // Convert units and do the real work.
 908   SGVec3d pt_m = SG_FEET_TO_METER*SGVec3d(pt);
 909
 910   const SGMaterial* material;
 911   SGVec3d _contact, _normal, _vel;
 912   bool ret = ground_cache.get_agl(t, pt_m, 2.0, _contact, _normal, _vel,
 913                                   type, &material, agl);
 914   // Convert units back ...
 915   sgdScaleVec3( contact, _contact.data(), SG_METER_TO_FEET );
 916   sgdScaleVec3( vel, _vel.data(), SG_METER_TO_FEET );
 917   sgdCopyVec3( normal, _normal.data() );
 918   *agl *= SG_METER_TO_FEET;
 919
 920   // return material properties if available
 921   if (material) {
 922     // FIXME: convert units?? now pascal to lbf/ft^2
 923     *loadCapacity = 0.020885434*material->get_load_resistence();
 924     *frictionFactor = material->get_friction_factor();
 925   } else {
 926     *loadCapacity = DBL_MAX;
 927     *frictionFactor = 1.0;
 928   }
 929   return ret;
 930 }
 931
 932 bool
 933 FGInterface::get_agl_m(double t, const double pt[3], double max_altoff,
 934                        double contact[3], double normal[3], double vel[3],
 935                        int *type, const SGMaterial** material, double *agl)
 936 {
 937   SGVec3d _contact, _normal, _vel;
 938   bool found = ground_cache.get_agl(t, SGVec3d(pt), max_altoff, _contact,
 939                                     _normal, _vel, type, material, agl);
 940   sgdCopyVec3(contact, _contact.data());
 941   sgdCopyVec3(normal, _normal.data());
 942   sgdCopyVec3(vel, _vel.data());
 943   return found;
 944 }
 945
 946 bool
 947 FGInterface::get_agl_ft(double t, const double pt[3], double max_altoff,
 948                         double contact[3], double normal[3], double vel[3],
 949                         int *type, const SGMaterial** material, double *agl)
 950 {
 951   // Convert units and do the real work.
 952   SGVec3d pt_m = SG_FEET_TO_METER*SGVec3d(pt);
 953   SGVec3d _contact, _normal, _vel;
 954   bool ret = ground_cache.get_agl(t, pt_m, SG_FEET_TO_METER * max_altoff,
 955                                   _contact, _normal, _vel,
 956                                   type, material, agl);
 957   // Convert units back ...
 958   sgdScaleVec3( contact, _contact.data(), SG_METER_TO_FEET );
 959   sgdScaleVec3( vel, _vel.data(), SG_METER_TO_FEET );
 960   sgdCopyVec3( normal, _normal.data() );
 961   *agl *= SG_METER_TO_FEET;
 962   return ret;
 963 }
 964
 965
 966 double
 967 FGInterface::get_groundlevel_m(double lat, double lon, double alt)
 968 {
 969   // Compute the cartesian position of the given lat/lon/alt.
 970   SGVec3d pos = SGVec3d::fromGeod(SGGeod::fromRadM(lon, lat, alt));
 971
 972   // FIXME: how to handle t - ref_time differences ???
 973   SGVec3d cpos;
 974   double ref_time, radius;
 975   // Prepare the ground cache for that position.
 976   if (!is_valid_m(&ref_time, cpos.data(), &radius)) {
 977     bool ok = prepare_ground_cache_m(ref_time, pos.data(), 10);
 978     /// This is most likely the case when the given altitude is
 979     /// too low, try with a new altitude of 10000m, that should be
 980     /// sufficient to find a ground level below everywhere on our planet
 981     if (!ok) {
 982       pos = SGVec3d::fromGeod(SGGeod::fromRadM(lon, lat, 10000));
 983       /// If there is still no ground, return sea level radius
 984       if (!prepare_ground_cache_m(ref_time, pos.data(), 10))
 985         return 0;
 986     }
 987   } else if (radius*radius <= distSqr(pos, cpos)) {
 988     /// We reuse the old radius value, but only if it is at least 10 Meters ..
 989     if (!(10 < radius)) // Well this strange compare is nan safe
 990       radius = 10;
 991
 992     bool ok = prepare_ground_cache_m(ref_time, pos.data(), radius);
 993     /// This is most likely the case when the given altitude is
 994     /// too low, try with a new altitude of 10000m, that should be
 995     /// sufficient to find a ground level below everywhere on our planet
 996     if (!ok) {
 997       pos = SGVec3d::fromGeod(SGGeod::fromRadM(lon, lat, 10000));
 998       /// If there is still no ground, return sea level radius
 999       if (!prepare_ground_cache_m(ref_time, pos.data(), radius))
1000         return 0;
1001     }
1002   }
1003
1004   double contact[3], normal[3], vel[3], agl;
1005   int type;
1006   // Ignore the return value here, since it just tells us if
1007   // the returns stem from the groundcache or from the coarse
1008   // computations below the groundcache. The contact point is still something
1009   // valid, the normals and the other returns just contain some defaults.
1010   get_agl_m(ref_time, pos.data(), 2.0, contact, normal, vel, &type, 0, &agl);
1011   SGGeod geod = SGGeod::fromCart(SGVec3d(contact));
1012   return geod.getElevationM();
1013 }
1014
1015 bool
1016 FGInterface::caught_wire_m(double t, const double pt[4][3])
1017 {
1018   SGVec3d pt_m[4];
1019   for (int i=0; i<4; ++i)
1020     sgdCopyVec3(pt_m[i].data(), pt[i]);
1021
1022   return ground_cache.caught_wire(t, pt_m);
1023 }
1024
1025 bool
1026 FGInterface::caught_wire_ft(double t, const double pt[4][3])
1027 {
1028   // Convert units and do the real work.
1029   SGVec3d pt_m[4];
1030   for (int i=0; i<4; ++i)
1031     sgdScaleVec3(pt_m[i].data(), pt[i], SG_FEET_TO_METER);
1032
1033   return ground_cache.caught_wire(t, pt_m);
1034 }
1035
1036 bool
1037 FGInterface::get_wire_ends_m(double t, double end[2][3], double vel[2][3])
1038 {
1039   SGVec3d _end[2], _vel[2];
1040   bool ret = ground_cache.get_wire_ends(t, _end, _vel);
1041   for (int k=0; k<2; ++k) {
1042     sgdCopyVec3( end[k], _end[k].data() );
1043     sgdCopyVec3( vel[k], _vel[k].data() );
1044   }
1045   return ret;
1046 }
1047
1048 bool
1049 FGInterface::get_wire_ends_ft(double t, double end[2][3], double vel[2][3])
1050 {
1051   // Convert units and do the real work.
1052   SGVec3d _end[2], _vel[2];
1053   bool ret = ground_cache.get_wire_ends(t, _end, _vel);
1054   for (int k=0; k<2; ++k) {
1055     sgdScaleVec3( end[k], _end[k].data(), SG_METER_TO_FEET );
1056     sgdScaleVec3( vel[k], _vel[k].data(), SG_METER_TO_FEET );
1057   }
1058   return ret;
1059 }
1060
1061 void
1062 FGInterface::release_wire(void)
1063 {
1064   ground_cache.release_wire();
1065 }
1066
1067 void fgToggleFDMdataLogging(void) {
1068   cur_fdm_state->ToggleDataLogging();
1069 }