src/FDM/JSBSim/JSBSim.cxx

   1 // JSBsim.cxx -- interface to the JSBsim flight model
   2 //
   3 // Written by Curtis Olson, started February 1999.
   4 //
   5 // Copyright (C) 1999  Curtis L. Olson  - curt@flightgear.org
   6 //
   7 // This program is free software; you can redistribute it and/or
   8 // modify it under the terms of the GNU Lesser 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 // Lesser General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU Lesser 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: JSBSim.cxx,v 1.64 2010/10/31 04:49:25 jberndt Exp $
  22
  23
  24 #ifdef HAVE_CONFIG_H
  25 #  include <config.h>
  26 #endif
  27
  28 #include <simgear/compiler.h>
  29 #include <simgear/sg_inlines.h>
  30
  31 #include <stdio.h>    //    size_t
  32 #include <string>
  33
  34 #include <simgear/constants.h>
  35 #include <simgear/debug/logstream.hxx>
  36 #include <simgear/math/sg_geodesy.hxx>
  37 #include <simgear/misc/sg_path.hxx>
  38 #include <simgear/structure/commands.hxx>
  39
  40 #include <FDM/flight.hxx>
  41
  42 #include <Aircraft/controls.hxx>
  43 #include <Main/globals.hxx>
  44 #include <Main/fg_props.hxx>
  45
  46 #include "JSBSim.hxx"
  47 #include <FDM/JSBSim/FGFDMExec.h>
  48 #include <FDM/JSBSim/FGJSBBase.h>
  49 #include <FDM/JSBSim/initialization/FGInitialCondition.h>
  50 #include <FDM/JSBSim/initialization/FGTrim.h>
  51 #include <FDM/JSBSim/models/FGModel.h>
  52 #include <FDM/JSBSim/models/FGAircraft.h>
  53 #include <FDM/JSBSim/models/FGFCS.h>
  54 #include <FDM/JSBSim/models/FGPropagate.h>
  55 #include <FDM/JSBSim/models/FGAuxiliary.h>
  56 #include <FDM/JSBSim/models/FGInertial.h>
  57 #include <FDM/JSBSim/models/FGAtmosphere.h>
  58 #include <FDM/JSBSim/models/FGMassBalance.h>
  59 #include <FDM/JSBSim/models/FGAerodynamics.h>
  60 #include <FDM/JSBSim/models/FGLGear.h>
  61 #include <FDM/JSBSim/models/FGGroundReactions.h>
  62 #include <FDM/JSBSim/models/FGPropulsion.h>
  63 #include <FDM/JSBSim/models/FGAccelerations.h>
  64 #include <FDM/JSBSim/models/atmosphere/FGWinds.h>
  65 #include <FDM/JSBSim/models/propulsion/FGEngine.h>
  66 #include <FDM/JSBSim/models/propulsion/FGPiston.h>
  67 #include <FDM/JSBSim/models/propulsion/FGTurbine.h>
  68 #include <FDM/JSBSim/models/propulsion/FGTurboProp.h>
  69 #include <FDM/JSBSim/models/propulsion/FGRocket.h>
  70 #include <FDM/JSBSim/models/propulsion/FGElectric.h>
  71 #include <FDM/JSBSim/models/propulsion/FGNozzle.h>
  72 #include <FDM/JSBSim/models/propulsion/FGPropeller.h>
  73 #include <FDM/JSBSim/models/propulsion/FGRotor.h>
  74 #include <FDM/JSBSim/models/propulsion/FGTank.h>
  75 #include <FDM/JSBSim/input_output/FGPropertyManager.h>
  76 #include <FDM/JSBSim/input_output/FGGroundCallback.h>
  77
  78 using namespace JSBSim;
  79
  80 static inline double
  81 FMAX (double a, double b)
  82 {
  83   return a > b ? a : b;
  84 }
  85
  86 class FGFSGroundCallback : public FGGroundCallback {
  87 public:
  88   FGFSGroundCallback(FGJSBsim* ifc) : mInterface(ifc) {}
  89   virtual ~FGFSGroundCallback() {}
  90
  91   /** Get the altitude above sea level dependent on the location. */
  92   virtual double GetAltitude(const FGLocation& l) const {
  93     double pt[3] = { SG_FEET_TO_METER*l(eX),
  94                      SG_FEET_TO_METER*l(eY),
  95                      SG_FEET_TO_METER*l(eZ) };
  96     double lat, lon, alt;
  97     sgCartToGeod( pt, &lat, &lon, &alt);
  98     return alt * SG_METER_TO_FEET;
  99   }
 100
 101   /** Compute the altitude above ground. */
 102   virtual double GetAGLevel(double t, const FGLocation& l,
 103                             FGLocation& cont, FGColumnVector3& n,
 104                             FGColumnVector3& v, FGColumnVector3& w) const {
 105     double loc_cart[3] = { l(eX), l(eY), l(eZ) };
 106     double contact[3], normal[3], vel[3], angularVel[3], agl = 0;
 107     mInterface->get_agl_ft(t, loc_cart, SG_METER_TO_FEET*2, contact, normal,
 108                            vel, angularVel, &agl);
 109     n = FGColumnVector3( normal[0], normal[1], normal[2] );
 110     v = FGColumnVector3( vel[0], vel[1], vel[2] );
 111     w = FGColumnVector3( angularVel[0], angularVel[1], angularVel[2] );
 112     cont = FGColumnVector3( contact[0], contact[1], contact[2] );
 113     return agl;
 114   }
 115
 116   virtual double GetTerrainGeoCentRadius(double t, const FGLocation& l) const {
 117     double loc_cart[3] = { l(eX), l(eY), l(eZ) };
 118     double contact[3], normal[3], vel[3], angularVel[3], agl = 0;
 119     mInterface->get_agl_ft(t, loc_cart, SG_METER_TO_FEET*2, contact, normal,
 120                            vel, angularVel, &agl);
 121     return sqrt(contact[0]*contact[0]+contact[1]*contact[1]+contact[2]*contact[2]);
 122   }
 123
 124   virtual double GetSeaLevelRadius(const FGLocation& l) const {
 125     double seaLevelRadius, latGeoc;
 126
 127     sgGeodToGeoc(l.GetGeodLatitudeRad(), l.GetGeodAltitude(),
 128                  &seaLevelRadius, &latGeoc);
 129
 130     return seaLevelRadius * SG_METER_TO_FEET;
 131   }
 132
 133   virtual void SetTerrainGeoCentRadius(double radius) {}
 134   virtual void SetSeaLevelRadius(double radius) {}
 135 private:
 136   FGJSBsim* mInterface;
 137 };
 138
 139 // FG uses a squared normalized magnitude for turbulence
 140 // this lookup table maps fg's severity levels
 141 // none(0), light(1/3), moderate(2/3) and severe(3/3)
 142 // to the POE table indexes 0, 3, 4 and 7
 143 class FGTurbulenceSeverityTable : public FGTable {
 144 public:
 145   FGTurbulenceSeverityTable() : FGTable(4) {
 146     *this << (0.0/9.0) << 0.0;
 147     *this << (1.0/9.0) << 3.0;
 148     *this << (4.0/9.0) << 4.0;
 149     *this << (9.0/9.0) << 7.0;
 150   }
 151 };
 152
 153 /******************************************************************************/
 154 std::map<std::string,int> FGJSBsim::TURBULENCE_TYPE_NAMES;
 155
 156 static FGTurbulenceSeverityTable TurbulenceSeverityTable;
 157
 158 FGJSBsim::FGJSBsim( double dt )
 159   : FGInterface(dt), got_wire(false)
 160 {
 161     bool result;
 162     if( TURBULENCE_TYPE_NAMES.empty() ) {
 163         TURBULENCE_TYPE_NAMES["ttNone"]     = FGWinds::ttNone;
 164         TURBULENCE_TYPE_NAMES["ttStandard"] = FGWinds::ttStandard;
 165         TURBULENCE_TYPE_NAMES["ttCulp"]     = FGWinds::ttCulp;
 166         TURBULENCE_TYPE_NAMES["ttMilspec"]  = FGWinds::ttMilspec;
 167         TURBULENCE_TYPE_NAMES["ttTustin"]   = FGWinds::ttTustin;
 168     }
 169
 170                                 // Set up the debugging level
 171                                 // FIXME: this will not respond to
 172                                 // runtime changes
 173
 174                                 // if flight is excluded, don't bother
 175     if ((logbuf::get_log_classes() & SG_FLIGHT) != 0) {
 176
 177                                 // do a rough-and-ready mapping to
 178                                 // the levels documented in FGFDMExec.h
 179         switch (logbuf::get_log_priority()) {
 180         case SG_BULK:
 181             FGJSBBase::debug_lvl = 0x1f;
 182             break;
 183         case SG_DEBUG:
 184             FGJSBBase::debug_lvl = 0x0f;
 185         case SG_INFO:
 186             FGJSBBase::debug_lvl = 0x01;
 187             break;
 188         case SG_WARN:
 189         case SG_ALERT:
 190             FGJSBBase::debug_lvl = 0x00;
 191             break;
 192         }
 193     }
 194
 195     fdmex = new FGFDMExec( (FGPropertyManager*)globals->get_props() );
 196
 197     // Register ground callback.
 198     fdmex->SetGroundCallback( new FGFSGroundCallback(this) );
 199
 200     Atmosphere      = fdmex->GetAtmosphere();
 201     Winds           = fdmex->GetWinds();
 202     FCS             = fdmex->GetFCS();
 203     MassBalance     = fdmex->GetMassBalance();
 204     Propulsion      = fdmex->GetPropulsion();
 205     Aircraft        = fdmex->GetAircraft();
 206     Propagate       = fdmex->GetPropagate();
 207     Auxiliary       = fdmex->GetAuxiliary();
 208     Inertial        = fdmex->GetInertial();
 209     Aerodynamics    = fdmex->GetAerodynamics();
 210     GroundReactions = fdmex->GetGroundReactions();
 211     Accelerations   = fdmex->GetAccelerations();
 212
 213     fgic=fdmex->GetIC();
 214     needTrim=true;
 215
 216     SGPath aircraft_path( fgGetString("/sim/aircraft-dir") );
 217
 218     SGPath engine_path( fgGetString("/sim/aircraft-dir") );
 219     engine_path.append( "Engine" );
 220
 221     SGPath systems_path( fgGetString("/sim/aircraft-dir") );
 222     systems_path.append( "Systems" );
 223
 224 // deprecate sim-time-sec for simulation/sim-time-sec
 225 // remove alias with increased configuration file version number (2.1 or later)
 226     SGPropertyNode * node = fgGetNode("/fdm/jsbsim/simulation/sim-time-sec");
 227     fgGetNode("/fdm/jsbsim/sim-time-sec", true)->alias( node );
 228 // end of sim-time-sec deprecation patch
 229
 230     fdmex->Setdt( dt );
 231
 232     result = fdmex->LoadModel( aircraft_path.str(),
 233                                engine_path.str(),
 234                                systems_path.str(),
 235                                fgGetString("/sim/aero"), false );
 236
 237     if (result) {
 238       SG_LOG( SG_FLIGHT, SG_INFO, "  loaded aero.");
 239     } else {
 240       SG_LOG( SG_FLIGHT, SG_INFO,
 241               "  aero does not exist (you may have mis-typed the name).");
 242       throw(-1);
 243     }
 244
 245     SG_LOG( SG_FLIGHT, SG_INFO, "" );
 246     SG_LOG( SG_FLIGHT, SG_INFO, "" );
 247     SG_LOG( SG_FLIGHT, SG_INFO, "After loading aero definition file ..." );
 248
 249     int Neng = Propulsion->GetNumEngines();
 250     SG_LOG( SG_FLIGHT, SG_INFO, "num engines = " << Neng );
 251
 252     if ( GroundReactions->GetNumGearUnits() <= 0 ) {
 253         SG_LOG( SG_FLIGHT, SG_ALERT, "num gear units = "
 254                 << GroundReactions->GetNumGearUnits() );
 255         SG_LOG( SG_FLIGHT, SG_ALERT, "This is a very bad thing because with 0 gear units, the ground trimming");
 256         SG_LOG( SG_FLIGHT, SG_ALERT, "routine (coming up later in the code) will core dump.");
 257         SG_LOG( SG_FLIGHT, SG_ALERT, "Halting the sim now, and hoping a solution will present itself soon!");
 258         exit(-1);
 259     }
 260
 261     init_gear();
 262
 263     // Set initial fuel levels if provided.
 264     for (unsigned int i = 0; i < Propulsion->GetNumTanks(); i++) {
 265       double d;
 266       SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 267       FGTank* tank = Propulsion->GetTank(i);
 268
 269       d = node->getNode( "density-ppg", true )->getDoubleValue();
 270       if( d > 0.0 ) {
 271         tank->SetDensity( d );
 272       } else {
 273         node->getNode( "density-ppg", true )->setDoubleValue( SG_MAX2<double>(tank->GetDensity(), 0.1) );
 274       }
 275
 276       d = node->getNode( "level-lbs", true )->getDoubleValue();
 277       if( d > 0.0 ) {
 278         tank->SetContents( d );
 279       } else {
 280         node->getNode( "level-lbs", true )->setDoubleValue( tank->GetContents() );
 281       }
 282       /* Capacity is read-only in FGTank and can't be overwritten from FlightGear */
 283       node->getNode("capacity-gal_us", true )->setDoubleValue( tank->GetCapacityGallons() );
 284     }
 285     Propulsion->SetFuelFreeze((fgGetNode("/sim/freeze/fuel",true))->getBoolValue());
 286
 287     fgSetDouble("/fdm/trim/pitch-trim", FCS->GetPitchTrimCmd());
 288     fgSetDouble("/fdm/trim/throttle",   FCS->GetThrottleCmd(0));
 289     fgSetDouble("/fdm/trim/aileron",    FCS->GetDaCmd());
 290     fgSetDouble("/fdm/trim/rudder",     FCS->GetDrCmd());
 291
 292     startup_trim = fgGetNode("/sim/presets/trim", true);
 293
 294     trimmed = fgGetNode("/fdm/trim/trimmed", true);
 295     trimmed->setBoolValue(false);
 296
 297     pitch_trim = fgGetNode("/fdm/trim/pitch-trim", true );
 298     throttle_trim = fgGetNode("/fdm/trim/throttle", true );
 299     aileron_trim = fgGetNode("/fdm/trim/aileron", true );
 300     rudder_trim = fgGetNode("/fdm/trim/rudder", true );
 301
 302     stall_warning = fgGetNode("/sim/alarms/stall-warning",true);
 303     stall_warning->setDoubleValue(0);
 304
 305
 306     flap_pos_pct=fgGetNode("/surface-positions/flap-pos-norm",true);
 307     elevator_pos_pct=fgGetNode("/surface-positions/elevator-pos-norm",true);
 308     left_aileron_pos_pct
 309         =fgGetNode("/surface-positions/left-aileron-pos-norm",true);
 310     right_aileron_pos_pct
 311         =fgGetNode("/surface-positions/right-aileron-pos-norm",true);
 312     rudder_pos_pct=fgGetNode("/surface-positions/rudder-pos-norm",true);
 313     speedbrake_pos_pct
 314         =fgGetNode("/surface-positions/speedbrake-pos-norm",true);
 315     spoilers_pos_pct=fgGetNode("/surface-positions/spoilers-pos-norm",true);
 316     tailhook_pos_pct=fgGetNode("/gear/tailhook/position-norm",true);
 317     wing_fold_pos_pct=fgGetNode("surface-positions/wing-fold-pos-norm",true);
 318
 319     elevator_pos_pct->setDoubleValue(0);
 320     left_aileron_pos_pct->setDoubleValue(0);
 321     right_aileron_pos_pct->setDoubleValue(0);
 322     rudder_pos_pct->setDoubleValue(0);
 323     flap_pos_pct->setDoubleValue(0);
 324     speedbrake_pos_pct->setDoubleValue(0);
 325     spoilers_pos_pct->setDoubleValue(0);
 326
 327     ab_brake_engaged = fgGetNode("/autopilot/autobrake/engaged", true);
 328     ab_brake_left_pct = fgGetNode("/autopilot/autobrake/brake-left-output", true);
 329     ab_brake_right_pct = fgGetNode("/autopilot/autobrake/brake-right-output", true);
 330
 331     temperature = fgGetNode("/environment/temperature-degc",true);
 332     pressure = fgGetNode("/environment/pressure-inhg",true);
 333     pressureSL = fgGetNode("/environment/pressure-sea-level-inhg",true);
 334     ground_wind = fgGetNode("/environment/config/boundary/entry[0]/wind-speed-kt",true);
 335     turbulence_gain = fgGetNode("/environment/turbulence/magnitude-norm",true);
 336     turbulence_rate = fgGetNode("/environment/turbulence/rate-hz",true);
 337     turbulence_model = fgGetNode("/environment/params/jsbsim-turbulence-model",true);
 338
 339     wind_from_north= fgGetNode("/environment/wind-from-north-fps",true);
 340     wind_from_east = fgGetNode("/environment/wind-from-east-fps" ,true);
 341     wind_from_down = fgGetNode("/environment/wind-from-down-fps" ,true);
 342
 343     slaved = fgGetNode("/sim/slaved/enabled", true);
 344
 345     for (unsigned int i = 0; i < Propulsion->GetNumEngines(); i++) {
 346       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 347       Propulsion->GetEngine(i)->GetThruster()->SetRPM(node->getDoubleValue("rpm") /
 348                      Propulsion->GetEngine(i)->GetThruster()->GetGearRatio());
 349     }
 350
 351     hook_root_struct = FGColumnVector3(
 352         fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-offset-x-in", 196),
 353         fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-offset-y-in", 0),
 354         fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-offset-z-in", -16));
 355     last_hook_tip[0] = 0; last_hook_tip[1] = 0; last_hook_tip[2] = 0;
 356     last_hook_root[0] = 0; last_hook_root[1] = 0; last_hook_root[2] = 0;
 357
 358     crashed = false;
 359 }
 360
 361 /******************************************************************************/
 362 FGJSBsim::~FGJSBsim(void)
 363 {
 364   delete fdmex;
 365 }
 366
 367 /******************************************************************************/
 368
 369 // Initialize the JSBsim flight model, dt is the time increment for
 370 // each subsequent iteration through the EOM
 371
 372 void FGJSBsim::init()
 373 {
 374     SG_LOG( SG_FLIGHT, SG_INFO, "Starting and initializing JSBsim" );
 375
 376     // Explicitly call the superclass's
 377     // init method first.
 378
 379     if (fgGetBool("/environment/params/control-fdm-atmosphere")) {
 380       Atmosphere->SetTemperature(temperature->getDoubleValue(), get_Altitude(), FGAtmosphere::eCelsius);
 381       Atmosphere->SetPressureSL(pressureSL->getDoubleValue(), FGAtmosphere::eInchesHg);
 382       // initialize to no turbulence, these values get set in the update loop
 383       Winds->SetTurbType(FGWinds::ttNone);
 384       Winds->SetTurbGain(0.0);
 385       Winds->SetTurbRate(0.0);
 386       Winds->SetWindspeed20ft(0.0);
 387       Winds->SetProbabilityOfExceedence(0.0);
 388     }
 389
 390     fgic->SetWindNEDFpsIC( -wind_from_north->getDoubleValue(),
 391                            -wind_from_east->getDoubleValue(),
 392                            -wind_from_down->getDoubleValue() );
 393
 394     SG_LOG(SG_FLIGHT,SG_INFO,"T,p,rho: " << Atmosphere->GetTemperature()
 395      << ", " << Atmosphere->GetPressure()
 396      << ", " << Atmosphere->GetDensity() );
 397
 398     FCS->SetDfPos( ofNorm, globals->get_controls()->get_flaps() );
 399
 400     needTrim = startup_trim->getBoolValue();
 401     common_init();
 402
 403     copy_to_JSBsim();
 404     fdmex->RunIC();     //loop JSBSim once w/o integrating
 405     if (fgGetBool("/sim/presets/running")) {
 406       Propulsion->InitRunning(-1);
 407       for (unsigned int i = 0; i < Propulsion->GetNumEngines(); i++) {
 408         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 409         globals->get_controls()->set_magnetos(i, eng->GetMagnetos());
 410         globals->get_controls()->set_mixture(i, FCS->GetMixtureCmd(i));
 411       }
 412     }
 413
 414     if ( needTrim ) {
 415       FGLocation cart(fgic->GetLongitudeRadIC(), fgic->GetLatitudeRadIC(),
 416                       get_Sea_level_radius() + fgic->GetAltitudeASLFtIC());
 417       double cart_pos[3], contact[3], d[3], vel[3], agl;
 418       update_ground_cache(cart, cart_pos, 0.01);
 419
 420       get_agl_ft(fdmex->GetSimTime(), cart_pos, SG_METER_TO_FEET*2, contact,
 421                  d, vel, d, &agl);
 422       double terrain_alt = sqrt(contact[0]*contact[0] + contact[1]*contact[1]
 423            + contact[2]*contact[2]) - get_Sea_level_radius();
 424
 425       SG_LOG(SG_FLIGHT, SG_INFO, "Ready to trim, terrain elevation is: "
 426                                  << terrain_alt * SG_METER_TO_FEET );
 427
 428       if (fgGetBool("/sim/presets/onground")) {
 429         FGColumnVector3 gndVelNED = cart.GetTec2l()
 430                                   * FGColumnVector3(vel[0], vel[1], vel[2]);
 431         fgic->SetVNorthFpsIC(gndVelNED(1));
 432         fgic->SetVEastFpsIC(gndVelNED(2));
 433         fgic->SetVDownFpsIC(gndVelNED(3));
 434       }
 435       fgic->SetTerrainElevationFtIC( terrain_alt );
 436       do_trim();
 437       needTrim = false;
 438     }
 439
 440     copy_from_JSBsim(); //update the bus
 441
 442     SG_LOG( SG_FLIGHT, SG_INFO, "  Initialized JSBSim with:" );
 443
 444     switch(fgic->GetSpeedSet()) {
 445     case setned:
 446         SG_LOG(SG_FLIGHT,SG_INFO, "  Vn,Ve,Vd= "
 447                << Propagate->GetVel(FGJSBBase::eNorth) << ", "
 448                << Propagate->GetVel(FGJSBBase::eEast) << ", "
 449                << Propagate->GetVel(FGJSBBase::eDown) << " ft/s");
 450     break;
 451     case setuvw:
 452         SG_LOG(SG_FLIGHT,SG_INFO, "  U,V,W= "
 453                << Propagate->GetUVW(1) << ", "
 454                << Propagate->GetUVW(2) << ", "
 455                << Propagate->GetUVW(3) << " ft/s");
 456     break;
 457     case setmach:
 458         SG_LOG(SG_FLIGHT,SG_INFO, "  Mach: "
 459                << Auxiliary->GetMach() );
 460     break;
 461     case setvc:
 462     default:
 463         SG_LOG(SG_FLIGHT,SG_INFO, "  Indicated Airspeed: "
 464                << Auxiliary->GetVcalibratedKTS() << " knots" );
 465     break;
 466     }
 467
 468     stall_warning->setDoubleValue(0);
 469
 470     SG_LOG( SG_FLIGHT, SG_INFO, "  Bank Angle: "
 471             << Propagate->GetEuler(FGJSBBase::ePhi)*RADTODEG << " deg" );
 472     SG_LOG( SG_FLIGHT, SG_INFO, "  Pitch Angle: "
 473             << Propagate->GetEuler(FGJSBBase::eTht)*RADTODEG << " deg" );
 474     SG_LOG( SG_FLIGHT, SG_INFO, "  True Heading: "
 475             << Propagate->GetEuler(FGJSBBase::ePsi)*RADTODEG << " deg" );
 476     SG_LOG( SG_FLIGHT, SG_INFO, "  Latitude: "
 477             << Propagate->GetLocation().GetLatitudeDeg() << " deg" );
 478     SG_LOG( SG_FLIGHT, SG_INFO, "  Longitude: "
 479             << Propagate->GetLocation().GetLongitudeDeg() << " deg" );
 480     SG_LOG( SG_FLIGHT, SG_INFO, "  Altitude: "
 481             << Propagate->GetAltitudeASL() << " feet" );
 482     SG_LOG( SG_FLIGHT, SG_INFO, "  loaded initial conditions" );
 483
 484     SG_LOG( SG_FLIGHT, SG_INFO, "  set dt" );
 485
 486     SG_LOG( SG_FLIGHT, SG_INFO, "Finished initializing JSBSim" );
 487
 488     SG_LOG( SG_FLIGHT, SG_INFO, "FGControls::get_gear_down()= " <<
 489                                   globals->get_controls()->get_gear_down() );
 490 }
 491
 492 /******************************************************************************/
 493
 494 void FGJSBsim::unbind()
 495 {
 496   fdmex->Unbind();
 497   FGInterface::unbind();
 498 }
 499
 500 /******************************************************************************/
 501
 502 // Run an iteration of the EOM (equations of motion)
 503
 504 void FGJSBsim::update( double dt )
 505 {
 506     if(crashed) {
 507       if(!fgGetBool("/sim/crashed"))
 508         fgSetBool("/sim/crashed", true);
 509       return;
 510     }
 511
 512     if (is_suspended())
 513       return;
 514
 515     int multiloop = _calc_multiloop(dt);
 516     FGLocation cart = Auxiliary->GetLocationVRP();
 517     double cart_pos[3];
 518
 519     update_ground_cache(cart, cart_pos, dt);
 520
 521     copy_to_JSBsim();
 522
 523     trimmed->setBoolValue(false);
 524
 525     for ( int i=0; i < multiloop; i++ ) {
 526       fdmex->Run();
 527       update_external_forces(fdmex->GetSimTime() + i * fdmex->GetDeltaT());
 528     }
 529
 530     FGJSBBase::Message* msg;
 531     while ((msg = fdmex->ProcessNextMessage()) != NULL) {
 532 //      msg = fdmex->ProcessNextMessage();
 533       switch (msg->type) {
 534       case FGJSBBase::Message::eText:
 535         if (msg->text == "Crash Detected: Simulation FREEZE.")
 536           crashed = true;
 537         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text );
 538         break;
 539       case FGJSBBase::Message::eBool:
 540         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->bVal );
 541         break;
 542       case FGJSBBase::Message::eInteger:
 543         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->iVal );
 544         break;
 545       case FGJSBBase::Message::eDouble:
 546         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->dVal );
 547         break;
 548       default:
 549         SG_LOG( SG_FLIGHT, SG_INFO, "Unrecognized message type." );
 550         break;
 551       }
 552     }
 553
 554     // translate JSBsim back to FG structure so that the
 555     // autopilot (and the rest of the sim can use the updated values
 556     copy_from_JSBsim();
 557 }
 558
 559 /******************************************************************************/
 560
 561 void FGJSBsim::suspend()
 562 {
 563   fdmex->Hold();
 564   SGSubsystem::suspend();
 565 }
 566
 567 /******************************************************************************/
 568
 569 void FGJSBsim::resume()
 570 {
 571   fdmex->Resume();
 572   SGSubsystem::resume();
 573 }
 574
 575 /******************************************************************************/
 576
 577 // Convert from the FGInterface struct to the JSBsim generic_ struct
 578
 579 bool FGJSBsim::copy_to_JSBsim()
 580 {
 581     unsigned int i;
 582
 583     // copy control positions into the JSBsim structure
 584
 585     FCS->SetDaCmd( globals->get_controls()->get_aileron());
 586     FCS->SetRollTrimCmd( globals->get_controls()->get_aileron_trim() );
 587     FCS->SetDeCmd( globals->get_controls()->get_elevator());
 588     FCS->SetPitchTrimCmd( globals->get_controls()->get_elevator_trim() );
 589     FCS->SetDrCmd( -globals->get_controls()->get_rudder() );
 590     FCS->SetYawTrimCmd( -globals->get_controls()->get_rudder_trim() );
 591     FCS->SetDsCmd( globals->get_controls()->get_rudder() );
 592     FCS->SetDfCmd( globals->get_controls()->get_flaps() );
 593     FCS->SetDsbCmd( globals->get_controls()->get_speedbrake() );
 594     FCS->SetDspCmd( globals->get_controls()->get_spoilers() );
 595
 596         // Parking brake sets minimum braking
 597         // level for mains.
 598     double parking_brake = globals->get_controls()->get_brake_parking();
 599     double left_brake = globals->get_controls()->get_brake_left();
 600     double right_brake = globals->get_controls()->get_brake_right();
 601
 602     if (ab_brake_engaged->getBoolValue()) {
 603       left_brake = ab_brake_left_pct->getDoubleValue();
 604       right_brake = ab_brake_right_pct->getDoubleValue();
 605     }
 606
 607     FCS->SetLBrake(FMAX(left_brake, parking_brake));
 608     FCS->SetRBrake(FMAX(right_brake, parking_brake));
 609
 610
 611     FCS->SetCBrake( 0.0 );
 612     // FCS->SetCBrake( globals->get_controls()->get_brake(2) );
 613
 614     FCS->SetGearCmd( globals->get_controls()->get_gear_down());
 615     for (i = 0; i < Propulsion->GetNumEngines(); i++) {
 616       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 617
 618       FCS->SetThrottleCmd(i, globals->get_controls()->get_throttle(i));
 619       FCS->SetMixtureCmd(i, globals->get_controls()->get_mixture(i));
 620       FCS->SetPropAdvanceCmd(i, globals->get_controls()->get_prop_advance(i));
 621       FCS->SetFeatherCmd(i, globals->get_controls()->get_feather(i));
 622
 623       switch (Propulsion->GetEngine(i)->GetType()) {
 624       case FGEngine::etPiston:
 625         { // FGPiston code block
 626         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 627         eng->SetMagnetos( globals->get_controls()->get_magnetos(i) );
 628         break;
 629         } // end FGPiston code block
 630       case FGEngine::etTurbine:
 631         { // FGTurbine code block
 632         FGTurbine* eng = (FGTurbine*)Propulsion->GetEngine(i);
 633         eng->SetAugmentation( globals->get_controls()->get_augmentation(i) );
 634         eng->SetReverse( globals->get_controls()->get_reverser(i) );
 635         //eng->SetInjection( globals->get_controls()->get_water_injection(i) );
 636         eng->SetCutoff( globals->get_controls()->get_cutoff(i) );
 637         eng->SetIgnition( globals->get_controls()->get_ignition(i) );
 638         break;
 639         } // end FGTurbine code block
 640       case FGEngine::etRocket:
 641         { // FGRocket code block
 642 //        FGRocket* eng = (FGRocket*)Propulsion->GetEngine(i);
 643         break;
 644         } // end FGRocket code block
 645       case FGEngine::etTurboprop:
 646         { // FGTurboProp code block
 647         FGTurboProp* eng = (FGTurboProp*)Propulsion->GetEngine(i);
 648         eng->SetReverse( globals->get_controls()->get_reverser(i) );
 649         eng->SetCutoff( globals->get_controls()->get_cutoff(i) );
 650         eng->SetIgnition( globals->get_controls()->get_ignition(i) );
 651
 652         eng->SetGeneratorPower( globals->get_controls()->get_generator_breaker(i) );
 653         eng->SetCondition( globals->get_controls()->get_condition(i) );
 654         break;
 655         } // end FGTurboProp code block
 656       default:
 657         break;
 658       }
 659
 660       { // FGEngine code block
 661       FGEngine* eng = Propulsion->GetEngine(i);
 662
 663       eng->SetStarter( globals->get_controls()->get_starter(i) );
 664       eng->SetRunning( node->getBoolValue("running") );
 665       } // end FGEngine code block
 666     }
 667
 668     Atmosphere->SetTemperature(temperature->getDoubleValue(), get_Altitude(), FGAtmosphere::eCelsius);
 669     Atmosphere->SetPressureSL(pressureSL->getDoubleValue(), FGAtmosphere::eInchesHg);
 670
 671     Winds->SetTurbType((FGWinds::tType)TURBULENCE_TYPE_NAMES[turbulence_model->getStringValue()]);
 672     switch( Winds->GetTurbType() ) {
 673         case FGWinds::ttStandard:
 674         case FGWinds::ttCulp: {
 675             double tmp = turbulence_gain->getDoubleValue();
 676             Winds->SetTurbGain(tmp * tmp * 100.0);
 677             Winds->SetTurbRate(turbulence_rate->getDoubleValue());
 678             break;
 679         }
 680         case FGWinds::ttMilspec:
 681         case FGWinds::ttTustin: {
 682             // milspec turbulence: 3=light, 4=moderate, 6=severe turbulence
 683             // turbulence_gain normalized: 0: none, 1/3: light, 2/3: moderate, 3/3: severe
 684             double tmp = turbulence_gain->getDoubleValue();
 685             Winds->SetProbabilityOfExceedence(
 686               SGMiscd::roundToInt(TurbulenceSeverityTable.GetValue( tmp ) )
 687             );
 688             Winds->SetWindspeed20ft(ground_wind->getDoubleValue());
 689             break;
 690         }
 691
 692         default:
 693             break;
 694     }
 695
 696     Winds->SetWindNED( -wind_from_north->getDoubleValue(),
 697                        -wind_from_east->getDoubleValue(),
 698                        -wind_from_down->getDoubleValue() );
 699 //    SG_LOG(SG_FLIGHT,SG_INFO, "Wind NED: "
 700 //                  << get_V_north_airmass() << ", "
 701 //                  << get_V_east_airmass()  << ", "
 702 //                  << get_V_down_airmass() );
 703
 704     for (i = 0; i < Propulsion->GetNumTanks(); i++) {
 705       SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 706       FGTank * tank = Propulsion->GetTank(i);
 707       double fuelDensity = node->getDoubleValue("density-ppg");
 708
 709       if (fuelDensity < 0.1)
 710         fuelDensity = 6.0; // Use average fuel value
 711
 712       tank->SetDensity(fuelDensity);
 713       tank->SetContents(node->getDoubleValue("level-lbs"));
 714     }
 715
 716     Propulsion->SetFuelFreeze((fgGetNode("/sim/freeze/fuel",true))->getBoolValue());
 717     fdmex->SetChild(slaved->getBoolValue());
 718
 719     return true;
 720 }
 721
 722 /******************************************************************************/
 723
 724 // Convert from the JSBsim generic_ struct to the FGInterface struct
 725
 726 bool FGJSBsim::copy_from_JSBsim()
 727 {
 728     unsigned int i, j;
 729 /*
 730     _set_Inertias( MassBalance->GetMass(),
 731                    MassBalance->GetIxx(),
 732                    MassBalance->GetIyy(),
 733                    MassBalance->GetIzz(),
 734                    MassBalance->GetIxz() );
 735 */
 736     _set_CG_Position( MassBalance->GetXYZcg(1),
 737                       MassBalance->GetXYZcg(2),
 738                       MassBalance->GetXYZcg(3) );
 739
 740     _set_Accels_Body( Accelerations->GetBodyAccel(1),
 741                       Accelerations->GetBodyAccel(2),
 742                       Accelerations->GetBodyAccel(3) );
 743
 744     _set_Accels_CG_Body_N ( Auxiliary->GetNcg(1),
 745                             Auxiliary->GetNcg(2),
 746                             Auxiliary->GetNcg(3) );
 747
 748     _set_Accels_Pilot_Body( Auxiliary->GetPilotAccel(1),
 749                             Auxiliary->GetPilotAccel(2),
 750                             Auxiliary->GetPilotAccel(3) );
 751
 752     _set_Nlf( Auxiliary->GetNlf() );
 753
 754     // Velocities
 755
 756     _set_Velocities_Local( Propagate->GetVel(FGJSBBase::eNorth),
 757                            Propagate->GetVel(FGJSBBase::eEast),
 758                            Propagate->GetVel(FGJSBBase::eDown) );
 759
 760     _set_Velocities_Wind_Body( Propagate->GetUVW(1),
 761                                Propagate->GetUVW(2),
 762                                Propagate->GetUVW(3) );
 763
 764     // Make the HUD work ...
 765     _set_Velocities_Ground( Propagate->GetVel(FGJSBBase::eNorth),
 766                             Propagate->GetVel(FGJSBBase::eEast),
 767                             -Propagate->GetVel(FGJSBBase::eDown) );
 768
 769     _set_V_rel_wind( Auxiliary->GetVt() );
 770
 771     _set_V_equiv_kts( Auxiliary->GetVequivalentKTS() );
 772
 773     _set_V_calibrated_kts( Auxiliary->GetVcalibratedKTS() );
 774
 775     _set_V_ground_speed( Auxiliary->GetVground() );
 776
 777     _set_Omega_Body( Propagate->GetPQR(FGJSBBase::eP),
 778                      Propagate->GetPQR(FGJSBBase::eQ),
 779                      Propagate->GetPQR(FGJSBBase::eR) );
 780
 781     _set_Euler_Rates( Auxiliary->GetEulerRates(FGJSBBase::ePhi),
 782                       Auxiliary->GetEulerRates(FGJSBBase::eTht),
 783                       Auxiliary->GetEulerRates(FGJSBBase::ePsi) );
 784
 785     _set_Mach_number( Auxiliary->GetMach() );
 786
 787     // Positions of Visual Reference Point
 788     FGLocation l = Auxiliary->GetLocationVRP();
 789     _updatePosition(SGGeoc::fromRadFt( l.GetLongitude(), l.GetLatitude(),
 790                                        l.GetRadius() ));
 791
 792     _set_Altitude_AGL( Propagate->GetDistanceAGL() );
 793     {
 794       double loc_cart[3] = { l(FGJSBBase::eX), l(FGJSBBase::eY), l(FGJSBBase::eZ) };
 795       double contact[3], d[3], sd, t;
 796       is_valid_m(&t, d, &sd);
 797       get_agl_ft(t, loc_cart, SG_METER_TO_FEET*2, contact, d, d, d, &sd);
 798       double rwrad
 799         = FGColumnVector3( contact[0], contact[1], contact[2] ).Magnitude();
 800       _set_Runway_altitude( rwrad - get_Sea_level_radius() );
 801     }
 802
 803     _set_Euler_Angles( Propagate->GetEuler(FGJSBBase::ePhi),
 804                        Propagate->GetEuler(FGJSBBase::eTht),
 805                        Propagate->GetEuler(FGJSBBase::ePsi) );
 806
 807     _set_Alpha( Auxiliary->Getalpha() );
 808     _set_Beta( Auxiliary->Getbeta() );
 809
 810
 811     _set_Gamma_vert_rad( Auxiliary->GetGamma() );
 812
 813     _set_Earth_position_angle( Propagate->GetEarthPositionAngle() );
 814
 815     _set_Climb_Rate( Propagate->Gethdot() );
 816
 817     const FGMatrix33& Tl2b = Propagate->GetTl2b();
 818     for ( i = 1; i <= 3; i++ ) {
 819         for ( j = 1; j <= 3; j++ ) {
 820             _set_T_Local_to_Body( i, j, Tl2b(i,j) );
 821         }
 822     }
 823
 824     // Copy the engine values from JSBSim.
 825     for ( i=0; i < Propulsion->GetNumEngines(); i++ ) {
 826       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 827       SGPropertyNode * tnode = node->getChild("thruster", 0, true);
 828       FGThruster * thruster = Propulsion->GetEngine(i)->GetThruster();
 829
 830       switch (Propulsion->GetEngine(i)->GetType()) {
 831       case FGEngine::etPiston:
 832         { // FGPiston code block
 833         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 834         node->setDoubleValue("egt-degf", eng->getExhaustGasTemp_degF());
 835         node->setDoubleValue("oil-temperature-degf", eng->getOilTemp_degF());
 836         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 837         node->setDoubleValue("mp-osi", eng->getManifoldPressure_inHg());
 838         // NOTE: mp-osi is not in ounces per square inch.
 839         // This error is left for reasons of backwards compatibility with
 840         // existing FlightGear sound and instrument configurations.
 841         node->setDoubleValue("mp-inhg", eng->getManifoldPressure_inHg());
 842         node->setDoubleValue("cht-degf", eng->getCylinderHeadTemp_degF());
 843         node->setDoubleValue("rpm", eng->getRPM());
 844         } // end FGPiston code block
 845         break;
 846       case FGEngine::etRocket:
 847         { // FGRocket code block
 848 //        FGRocket* eng = (FGRocket*)Propulsion->GetEngine(i);
 849         } // end FGRocket code block
 850         break;
 851       case FGEngine::etTurbine:
 852         { // FGTurbine code block
 853         FGTurbine* eng = (FGTurbine*)Propulsion->GetEngine(i);
 854         node->setDoubleValue("n1", eng->GetN1());
 855         node->setDoubleValue("n2", eng->GetN2());
 856         node->setDoubleValue("egt-degf", 32 + eng->GetEGT()*9/5);
 857         node->setBoolValue("augmentation", eng->GetAugmentation());
 858         node->setBoolValue("water-injection", eng->GetInjection());
 859         node->setBoolValue("ignition", eng->GetIgnition() != 0);
 860         node->setDoubleValue("nozzle-pos-norm", eng->GetNozzle());
 861         node->setDoubleValue("inlet-pos-norm", eng->GetInlet());
 862         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 863         node->setBoolValue("reversed", eng->GetReversed());
 864         node->setBoolValue("cutoff", eng->GetCutoff());
 865         node->setDoubleValue("epr", eng->GetEPR());
 866         globals->get_controls()->set_reverser(i, eng->GetReversed() );
 867         globals->get_controls()->set_cutoff(i, eng->GetCutoff() );
 868         globals->get_controls()->set_water_injection(i, eng->GetInjection() );
 869         globals->get_controls()->set_augmentation(i, eng->GetAugmentation() );
 870         } // end FGTurbine code block
 871         break;
 872       case FGEngine::etTurboprop:
 873         { // FGTurboProp code block
 874         FGTurboProp* eng = (FGTurboProp*)Propulsion->GetEngine(i);
 875         node->setDoubleValue("n1", eng->GetN1());
 876         //node->setDoubleValue("n2", eng->GetN2());
 877         node->setDoubleValue("itt_degf", 32 + eng->GetITT()*9/5);
 878         node->setBoolValue("ignition", eng->GetIgnition() != 0);
 879         node->setDoubleValue("nozzle-pos-norm", eng->GetNozzle());
 880         node->setDoubleValue("inlet-pos-norm", eng->GetInlet());
 881         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 882         node->setBoolValue("reversed", eng->GetReversed());
 883         node->setBoolValue("cutoff", eng->GetCutoff());
 884         node->setBoolValue("starting", eng->GetEngStarting());
 885         node->setBoolValue("generator-power", eng->GetGeneratorPower());
 886         node->setBoolValue("damaged", eng->GetCondition() != 0);
 887         node->setBoolValue("ielu-intervent", eng->GetIeluIntervent());
 888         node->setDoubleValue("oil-temperature-degf", eng->getOilTemp_degF());
 889 //        node->setBoolValue("onfire", eng->GetFire());
 890         globals->get_controls()->set_reverser(i, eng->GetReversed() );
 891         globals->get_controls()->set_cutoff(i, eng->GetCutoff() );
 892         } // end FGTurboProp code block
 893         break;
 894       case FGEngine::etElectric:
 895         { // FGElectric code block
 896         FGElectric* eng = (FGElectric*)Propulsion->GetEngine(i);
 897         node->setDoubleValue("rpm", eng->getRPM());
 898         } // end FGElectric code block
 899         break;
 900       case FGEngine::etUnknown:
 901         break;
 902       }
 903
 904       { // FGEngine code block
 905       FGEngine* eng = Propulsion->GetEngine(i);
 906       node->setDoubleValue("fuel-flow-gph", eng->getFuelFlow_gph());
 907       node->setDoubleValue("thrust_lb", thruster->GetThrust());
 908       node->setDoubleValue("fuel-flow_pph", eng->getFuelFlow_pph());
 909       node->setBoolValue("running", eng->GetRunning());
 910       node->setBoolValue("starter", eng->GetStarter());
 911       node->setBoolValue("cranking", eng->GetCranking());
 912       globals->get_controls()->set_starter(i, eng->GetStarter() );
 913       } // end FGEngine code block
 914
 915       switch (thruster->GetType()) {
 916       case FGThruster::ttNozzle:
 917         { // FGNozzle code block
 918 //        FGNozzle* noz = (FGNozzle*)thruster;
 919         } // end FGNozzle code block
 920         break;
 921       case FGThruster::ttPropeller:
 922         { // FGPropeller code block
 923         FGPropeller* prop = (FGPropeller*)thruster;
 924         tnode->setDoubleValue("rpm", thruster->GetRPM());
 925         tnode->setDoubleValue("pitch", prop->GetPitch());
 926         tnode->setDoubleValue("torque", prop->GetTorque());
 927         tnode->setBoolValue("feathered", prop->GetFeather());
 928         } // end FGPropeller code block
 929         break;
 930       case FGThruster::ttRotor:
 931         { // FGRotor code block
 932 //        FGRotor* rotor = (FGRotor*)thruster;
 933         } // end FGRotor code block
 934         break;
 935       case FGThruster::ttDirect:
 936         { // Direct code block
 937         } // end Direct code block
 938         break;
 939       }
 940
 941     }
 942
 943     // Copy the fuel levels from JSBSim if fuel
 944     // freeze not enabled.
 945     if ( ! Propulsion->GetFuelFreeze() ) {
 946       for (i = 0; i < Propulsion->GetNumTanks(); i++) {
 947         SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 948         FGTank* tank = Propulsion->GetTank(i);
 949         double contents = tank->GetContents();
 950         double temp = tank->GetTemperature_degC();
 951         double fuelDensity = tank->GetDensity();
 952
 953         if (fuelDensity < 0.1)
 954           fuelDensity = 6.0; // Use average fuel value
 955
 956         node->setDoubleValue("density-ppg" , fuelDensity);
 957         node->setDoubleValue("level-lbs", contents);
 958         if (temp != -9999.0) node->setDoubleValue("temperature_degC", temp);
 959       }
 960     }
 961
 962     update_gear();
 963
 964     stall_warning->setDoubleValue( Aerodynamics->GetStallWarn() );
 965
 966     elevator_pos_pct->setDoubleValue( FCS->GetDePos(ofNorm) );
 967     left_aileron_pos_pct->setDoubleValue( FCS->GetDaLPos(ofNorm) );
 968     right_aileron_pos_pct->setDoubleValue( FCS->GetDaRPos(ofNorm) );
 969     rudder_pos_pct->setDoubleValue( -1*FCS->GetDrPos(ofNorm) );
 970     flap_pos_pct->setDoubleValue( FCS->GetDfPos(ofNorm) );
 971     speedbrake_pos_pct->setDoubleValue( FCS->GetDsbPos(ofNorm) );
 972     spoilers_pos_pct->setDoubleValue( FCS->GetDspPos(ofNorm) );
 973     tailhook_pos_pct->setDoubleValue( FCS->GetTailhookPos() );
 974     wing_fold_pos_pct->setDoubleValue( FCS->GetWingFoldPos() );
 975
 976     // force a sim crashed if crashed (altitude AGL < 0)
 977     if (get_Altitude_AGL() < -100.0) {
 978          fdmex->SuspendIntegration();
 979          crashed = true;
 980     }
 981
 982     return true;
 983 }
 984
 985
 986 bool FGJSBsim::ToggleDataLogging(void)
 987 {
 988   // ToDo: handle this properly
 989   fdmex->DisableOutput();
 990   return false;
 991 }
 992
 993
 994 bool FGJSBsim::ToggleDataLogging(bool state)
 995 {
 996     if (state) {
 997       fdmex->EnableOutput();
 998       return true;
 999     } else {
1000       fdmex->DisableOutput();
1001       return false;
1002     }
1003 }
1004
1005
1006 //Positions
1007 void FGJSBsim::set_Latitude(double lat)
1008 {
1009   static SGConstPropertyNode_ptr altitude = fgGetNode("/position/altitude-ft");
1010   double alt = altitude->getDoubleValue();
1011   double sea_level_radius_meters, lat_geoc;
1012
1013   if ( alt < -9990 ) alt = 0.0;
1014
1015   SG_LOG(SG_FLIGHT,SG_INFO,"FGJSBsim::set_Latitude: " << lat );
1016   SG_LOG(SG_FLIGHT,SG_INFO," cur alt (ft) =  " << alt );
1017
1018   sgGeodToGeoc( lat, alt * SG_FEET_TO_METER,
1019                     &sea_level_radius_meters, &lat_geoc );
1020
1021   double sea_level_radius_ft = sea_level_radius_meters * SG_METER_TO_FEET;
1022   _set_Sea_level_radius( sea_level_radius_ft );
1023
1024   if (needTrim) {
1025     fgic->SetSeaLevelRadiusFtIC( sea_level_radius_ft );
1026     fgic->SetLatitudeRadIC( lat_geoc );
1027   }
1028   else
1029     Propagate->SetLatitude(lat_geoc);
1030
1031   FGInterface::set_Latitude(lat);
1032 }
1033
1034
1035 void FGJSBsim::set_Longitude(double lon)
1036 {
1037   SG_LOG(SG_FLIGHT,SG_INFO,"FGJSBsim::set_Longitude: " << lon );
1038
1039   if (needTrim)
1040     fgic->SetLongitudeRadIC(lon);
1041   else
1042     Propagate->SetLongitude(lon);
1043
1044   FGInterface::set_Longitude(lon);
1045 }
1046
1047 // Sets the altitude above sea level.
1048 void FGJSBsim::set_Altitude(double alt)
1049 {
1050   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Altitude: " << alt );
1051
1052   if (needTrim)
1053     fgic->SetAltitudeASLFtIC(alt);
1054   else
1055     Propagate->SetAltitudeASL(alt);
1056
1057   FGInterface::set_Altitude(alt);
1058 }
1059
1060 void FGJSBsim::set_V_calibrated_kts(double vc)
1061 {
1062     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_V_calibrated_kts: " <<  vc );
1063
1064   if (needTrim)
1065     fgic->SetVcalibratedKtsIC(vc);
1066   else {
1067     double p=pressure->getDoubleValue();
1068     double psl=fdmex->GetAtmosphere()->GetPressureSL();
1069     double rhosl=fdmex->GetAtmosphere()->GetDensitySL();
1070     double mach = FGJSBBase::MachFromVcalibrated(vc, p, psl, rhosl);
1071     double temp = 1.8*(temperature->getDoubleValue()+273.15);
1072     double soundSpeed = sqrt(1.4*1716.0*temp);
1073     FGColumnVector3 vUVW = Propagate->GetUVW();
1074     vUVW.Normalize();
1075     vUVW *= mach * soundSpeed;
1076     Propagate->SetUVW(1, vUVW(1));
1077     Propagate->SetUVW(2, vUVW(2));
1078     Propagate->SetUVW(3, vUVW(3));
1079   }
1080
1081   FGInterface::set_V_calibrated_kts(vc);
1082 }
1083
1084 void FGJSBsim::set_Mach_number(double mach)
1085 {
1086   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Mach_number: " <<  mach );
1087
1088   if (needTrim)
1089     fgic->SetMachIC(mach);
1090   else {
1091     double temp = 1.8*(temperature->getDoubleValue()+273.15);
1092     double soundSpeed = sqrt(1.4*1716.0*temp);
1093     FGColumnVector3 vUVW = Propagate->GetUVW();
1094     vUVW.Normalize();
1095     vUVW *= mach * soundSpeed;
1096     Propagate->SetUVW(1, vUVW(1));
1097     Propagate->SetUVW(2, vUVW(2));
1098     Propagate->SetUVW(3, vUVW(3));
1099   }
1100
1101   FGInterface::set_Mach_number(mach);
1102 }
1103
1104 void FGJSBsim::set_Velocities_Local( double north, double east, double down )
1105 {
1106   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Velocities_Local: "
1107      << north << ", " <<  east << ", " << down );
1108
1109   if (needTrim) {
1110     fgic->SetVNorthFpsIC(north);
1111     fgic->SetVEastFpsIC(east);
1112     fgic->SetVDownFpsIC(down);
1113   }
1114   else {
1115     FGColumnVector3 vNED(north, east, down);
1116     FGColumnVector3 vUVW = Propagate->GetTl2b() * vNED;
1117     Propagate->SetUVW(1, vUVW(1));
1118     Propagate->SetUVW(2, vUVW(2));
1119     Propagate->SetUVW(3, vUVW(3));
1120   }
1121
1122   FGInterface::set_Velocities_Local(north, east, down);
1123 }
1124
1125 void FGJSBsim::set_Velocities_Wind_Body( double u, double v, double w)
1126 {
1127   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Velocities_Wind_Body: "
1128      << u << ", " <<  v << ", " <<  w );
1129
1130   if (needTrim) {
1131     fgic->SetUBodyFpsIC(u);
1132     fgic->SetVBodyFpsIC(v);
1133     fgic->SetWBodyFpsIC(w);
1134   }
1135   else {
1136     Propagate->SetUVW(1, u);
1137     Propagate->SetUVW(2, v);
1138     Propagate->SetUVW(3, w);
1139   }
1140
1141   FGInterface::set_Velocities_Wind_Body(u, v, w);
1142 }
1143
1144 //Euler angles
1145 void FGJSBsim::set_Euler_Angles( double phi, double theta, double psi )
1146 {
1147   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Euler_Angles: "
1148      << phi << ", " << theta << ", " << psi );
1149
1150   if (needTrim) {
1151     fgic->SetThetaRadIC(theta);
1152     fgic->SetPhiRadIC(phi);
1153     fgic->SetPsiRadIC(psi);
1154   }
1155   else {
1156     FGQuaternion quat(phi, theta, psi);
1157     FGMatrix33 Tl2b = quat.GetT();
1158     FGMatrix33 Ti2b = Tl2b*Propagate->GetTi2l();
1159     FGQuaternion Qi = Ti2b.GetQuaternion();
1160     Propagate->SetInertialOrientation(Qi);
1161   }
1162
1163   FGInterface::set_Euler_Angles(phi, theta, psi);
1164 }
1165
1166 //Flight Path
1167 void FGJSBsim::set_Climb_Rate( double roc)
1168 {
1169   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Climb_Rate: " << roc );
1170
1171   //since both climb rate and flight path angle are set in the FG
1172   //startup sequence, something is needed to keep one from cancelling
1173   //out the other.
1174   if( !(fabs(roc) > 1 && fabs(fgic->GetFlightPathAngleRadIC()) < 0.01) ) {
1175     if (needTrim)
1176       fgic->SetClimbRateFpsIC(roc);
1177     else {
1178       FGColumnVector3 vNED = Propagate->GetVel();
1179       vNED(FGJSBBase::eDown) = -roc;
1180       FGColumnVector3 vUVW = Propagate->GetTl2b() * vNED;
1181       Propagate->SetUVW(1, vUVW(1));
1182       Propagate->SetUVW(2, vUVW(2));
1183       Propagate->SetUVW(3, vUVW(3));
1184     }
1185
1186     FGInterface::set_Climb_Rate(roc);
1187   }
1188 }
1189
1190 void FGJSBsim::set_Gamma_vert_rad( double gamma)
1191 {
1192   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Gamma_vert_rad: " << gamma );
1193
1194   if( !(fabs(gamma) < 0.01 && fabs(fgic->GetClimbRateFpsIC()) > 1) ) {
1195     if (needTrim)
1196       fgic->SetFlightPathAngleRadIC(gamma);
1197     else {
1198       FGColumnVector3 vNED = Propagate->GetVel();
1199       double vt = vNED.Magnitude();
1200       vNED(FGJSBBase::eDown) = -vt * sin(gamma);
1201       FGColumnVector3 vUVW = Propagate->GetTl2b() * vNED;
1202       Propagate->SetUVW(1, vUVW(1));
1203       Propagate->SetUVW(2, vUVW(2));
1204       Propagate->SetUVW(3, vUVW(3));
1205     }
1206
1207     FGInterface::set_Gamma_vert_rad(gamma);
1208   }
1209 }
1210
1211 void FGJSBsim::init_gear(void )
1212 {
1213     FGGroundReactions* gr=fdmex->GetGroundReactions();
1214     int Ngear=GroundReactions->GetNumGearUnits();
1215     for (int i=0;i<Ngear;i++) {
1216       FGLGear *gear = gr->GetGearUnit(i);
1217       SGPropertyNode * node = fgGetNode("gear/gear", i, true);
1218       node->setDoubleValue("xoffset-in", gear->GetBodyLocation()(1));
1219       node->setDoubleValue("yoffset-in", gear->GetBodyLocation()(2));
1220       node->setDoubleValue("zoffset-in", gear->GetBodyLocation()(3));
1221       node->setBoolValue("wow", gear->GetWOW());
1222       node->setDoubleValue("rollspeed-ms", gear->GetWheelRollVel()*0.3043);
1223       node->setBoolValue("has-brake", gear->GetBrakeGroup() > 0);
1224       node->setDoubleValue("position-norm", gear->GetGearUnitPos());
1225       node->setDoubleValue("tire-pressure-norm", gear->GetTirePressure());
1226       node->setDoubleValue("compression-norm", gear->GetCompLen());
1227       node->setDoubleValue("compression-ft", gear->GetCompLen());
1228       if ( gear->GetSteerable() )
1229         node->setDoubleValue("steering-norm", gear->GetSteerNorm());
1230     }
1231 }
1232
1233 void FGJSBsim::update_gear(void)
1234 {
1235     FGGroundReactions* gr=fdmex->GetGroundReactions();
1236     int Ngear=GroundReactions->GetNumGearUnits();
1237     for (int i=0;i<Ngear;i++) {
1238       FGLGear *gear = gr->GetGearUnit(i);
1239       SGPropertyNode * node = fgGetNode("gear/gear", i, true);
1240       node->getChild("wow", 0, true)->setBoolValue( gear->GetWOW());
1241       node->getChild("rollspeed-ms", 0, true)->setDoubleValue(gear->GetWheelRollVel()*0.3043);
1242       node->getChild("position-norm", 0, true)->setDoubleValue(gear->GetGearUnitPos());
1243       gear->SetTirePressure(node->getDoubleValue("tire-pressure-norm"));
1244       node->setDoubleValue("compression-norm", gear->GetCompLen());
1245       node->setDoubleValue("compression-ft", gear->GetCompLen());
1246       if ( gear->GetSteerable() )
1247         node->setDoubleValue("steering-norm", gear->GetSteerNorm());
1248     }
1249 }
1250
1251 void FGJSBsim::do_trim(void)
1252 {
1253   FGTrim *fgtrim;
1254
1255   if ( fgGetBool("/sim/presets/onground") )
1256   {
1257     fgtrim = new FGTrim(fdmex,tGround);
1258   } else {
1259     fgtrim = new FGTrim(fdmex,tFull);
1260   }
1261
1262   if ( !fgtrim->DoTrim() ) {
1263     fgtrim->Report();
1264     fgtrim->TrimStats();
1265   } else {
1266     trimmed->setBoolValue(true);
1267   }
1268   delete fgtrim;
1269
1270   pitch_trim->setDoubleValue( FCS->GetPitchTrimCmd() );
1271   throttle_trim->setDoubleValue( FCS->GetThrottleCmd(0) );
1272   aileron_trim->setDoubleValue( FCS->GetDaCmd() );
1273   rudder_trim->setDoubleValue( -FCS->GetDrCmd() );
1274
1275   globals->get_controls()->set_elevator_trim(FCS->GetPitchTrimCmd());
1276   globals->get_controls()->set_elevator(FCS->GetDeCmd());
1277   for( unsigned i = 0; i < Propulsion->GetNumEngines(); i++ )
1278     globals->get_controls()->set_throttle(i, FCS->GetThrottleCmd(i));
1279
1280   globals->get_controls()->set_aileron(FCS->GetDaCmd());
1281   globals->get_controls()->set_rudder( -FCS->GetDrCmd());
1282
1283   SG_LOG( SG_FLIGHT, SG_INFO, "  Trim complete" );
1284 }
1285
1286 bool FGJSBsim::update_ground_cache(FGLocation cart, double* cart_pos, double dt)
1287 {
1288   // Compute the radius of the aircraft. That is the radius of a ball
1289   // where all gear units are in. At the moment it is at least 10ft ...
1290   double acrad = 10.0;
1291   int n_gears = GroundReactions->GetNumGearUnits();
1292   for (int i=0; i<n_gears; ++i) {
1293     FGColumnVector3 bl = GroundReactions->GetGearUnit(i)->GetBodyLocation();
1294     double r = bl.Magnitude();
1295     if (acrad < r)
1296       acrad = r;
1297   }
1298
1299   // Compute the potential movement of this aircraft and query for the
1300   // ground in this area.
1301   double groundCacheRadius = acrad + 2*dt*Propagate->GetUVW().Magnitude();
1302   cart_pos[0] = cart(1);
1303   cart_pos[1] = cart(2);
1304   cart_pos[2] = cart(3);
1305   double t0 = fdmex->GetSimTime();
1306   bool cache_ok = prepare_ground_cache_ft( t0, t0 + dt, cart_pos,
1307                                            groundCacheRadius );
1308   if (!cache_ok) {
1309     SG_LOG(SG_FLIGHT, SG_WARN,
1310            "FGInterface is being called without scenery below the aircraft!");
1311
1312     SG_LOG(SG_FLIGHT, SG_WARN, "altitude         = "
1313                       << fgic->GetAltitudeASLFtIC());
1314
1315     SG_LOG(SG_FLIGHT, SG_WARN, "sea level radius = "
1316                       << get_Sea_level_radius());
1317
1318     SG_LOG(SG_FLIGHT, SG_WARN, "latitude         = "
1319                       << fgic->GetLatitudeRadIC());
1320
1321     SG_LOG(SG_FLIGHT, SG_WARN, "longitude        = "
1322                       << fgic->GetLongitudeRadIC());
1323   }
1324
1325   return cache_ok;
1326 }
1327
1328 bool
1329 FGJSBsim::get_agl_ft(double t, const double pt[3], double alt_off,
1330                      double contact[3], double normal[3], double vel[3],
1331                      double angularVel[3], double *agl)
1332 {
1333    const SGMaterial* material;
1334    simgear::BVHNode::Id id;
1335    if (!FGInterface::get_agl_ft(t, pt, alt_off, contact, normal, vel,
1336                                 angularVel, material, id))
1337        return false;
1338    SGGeod geodPt = SGGeod::fromCart(SG_FEET_TO_METER*SGVec3d(pt));
1339    SGQuatd hlToEc = SGQuatd::fromLonLat(geodPt);
1340    *agl = dot(hlToEc.rotate(SGVec3d(0, 0, 1)), SGVec3d(contact) - SGVec3d(pt));
1341    return true;
1342 }
1343
1344 inline static double sqr(double x)
1345 {
1346     return x * x;
1347 }
1348
1349 static double angle_diff(double a, double b)
1350 {
1351     double diff = fabs(a - b);
1352     if (diff > 180) diff = 360 - diff;
1353
1354     return diff;
1355 }
1356
1357 static void check_hook_solution(const FGColumnVector3& ground_normal_body, double E, double hook_length, double sin_fi_guess, double cos_fi_guess, double* sin_fis, double* cos_fis, double* fis, int* points)
1358 {
1359     FGColumnVector3 tip(-hook_length * cos_fi_guess, 0, hook_length * sin_fi_guess);
1360     double dist = DotProduct(tip, ground_normal_body);
1361     if (fabs(dist + E) < 0.0001) {
1362         sin_fis[*points] = sin_fi_guess;
1363         cos_fis[*points] = cos_fi_guess;
1364         fis[*points] = atan2(sin_fi_guess, cos_fi_guess) * SG_RADIANS_TO_DEGREES;
1365         (*points)++;
1366     }
1367 }
1368
1369
1370 static void check_hook_solution(const FGColumnVector3& ground_normal_body, double E, double hook_length, double sin_fi_guess, double* sin_fis, double* cos_fis, double* fis, int* points)
1371 {
1372     if (sin_fi_guess >= -1 && sin_fi_guess <= 1) {
1373         double cos_fi_guess = sqrt(1 - sqr(sin_fi_guess));
1374         check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, cos_fi_guess, sin_fis, cos_fis, fis, points);
1375         if (fabs(cos_fi_guess) > SG_EPSILON) {
1376             check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, -cos_fi_guess, sin_fis, cos_fis, fis, points);
1377         }
1378     }
1379 }
1380
1381 void FGJSBsim::update_external_forces(double t_off)
1382 {
1383     const FGMatrix33& Tb2l = Propagate->GetTb2l();
1384     const FGMatrix33& Tl2b = Propagate->GetTl2b();
1385     const FGLocation& Location = Propagate->GetLocation();
1386     const FGMatrix33& Tec2l = Location.GetTec2l();
1387
1388     double hook_area[4][3];
1389
1390     FGColumnVector3 hook_root_body = MassBalance->StructuralToBody(hook_root_struct);
1391     FGColumnVector3 hook_root = Location.LocalToLocation(Tb2l *   hook_root_body);
1392     hook_area[1][0] = hook_root(1);
1393     hook_area[1][1] = hook_root(2);
1394     hook_area[1][2] = hook_root(3);
1395
1396     hook_length = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-length-ft", 6.75);
1397     double fi_min = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-min-deg", -18);
1398     double fi_max = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-max-deg", 30);
1399     double fi = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-norm") * (fi_max - fi_min) + fi_min;
1400     double cos_fi = cos(fi * SG_DEGREES_TO_RADIANS);
1401     double sin_fi = sin(fi * SG_DEGREES_TO_RADIANS);
1402
1403     FGColumnVector3 hook_tip_body = hook_root_body;
1404     hook_tip_body(1) -= hook_length * cos_fi;
1405     hook_tip_body(3) += hook_length * sin_fi;
1406
1407     double contact[3];
1408     double ground_normal[3];
1409     double ground_vel[3];
1410     double ground_angular_vel[3];
1411     double root_agl_ft;
1412
1413     if (!got_wire) {
1414         bool got = get_agl_ft(t_off, hook_area[1], 0, contact, ground_normal,
1415                               ground_vel, ground_angular_vel, &root_agl_ft);
1416         if (got && root_agl_ft > 0 && root_agl_ft < hook_length) {
1417             FGColumnVector3 ground_normal_body = Tl2b * (Tec2l * FGColumnVector3(ground_normal[0], ground_normal[1], ground_normal[2]));
1418             FGColumnVector3 contact_body = Tl2b * Location.LocationToLocal(FGColumnVector3(contact[0], contact[1], contact[2]));
1419             double D = -DotProduct(contact_body, ground_normal_body);
1420
1421             // check hook tip agl against same ground plane
1422             double hook_tip_agl_ft = DotProduct(hook_tip_body, ground_normal_body) + D;
1423             if (hook_tip_agl_ft < 0) {
1424
1425                 // hook tip: hx - l cos, hy, hz + l sin
1426                 // on ground:  - n0 l cos + n2 l sin + E = 0
1427
1428                 double E = D + DotProduct(hook_root_body, ground_normal_body);
1429
1430                 // substitue x = sin fi, cos fi = sqrt(1 - x * x)
1431                 // and rearrange to get a quadratic with coeffs:
1432                 double a = sqr(hook_length) * (sqr(ground_normal_body(1)) + sqr(ground_normal_body(3)));
1433                 double b = 2 * E * ground_normal_body(3) * hook_length;
1434                 double c = sqr(E) - sqr(ground_normal_body(1) * hook_length);
1435
1436                 double disc = sqr(b) - 4 * a * c;
1437                 if (disc >= 0) {
1438                     double delta = sqrt(disc) / (2 * a);
1439
1440                     // allow 4 solutions for safety, should never happen
1441                     double sin_fis[4];
1442                     double cos_fis[4];
1443                     double fis[4];
1444                     int points = 0;
1445
1446                     double sin_fi_guess = -b / (2 * a) - delta;
1447                     check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, sin_fis, cos_fis, fis, &points);
1448                     check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess + 2 * delta, sin_fis, cos_fis, fis, &points);
1449
1450                     if (points == 2) {
1451                         double diff1 = angle_diff(fi, fis[0]);
1452                         double diff2 = angle_diff(fi, fis[1]);
1453                         int point = diff1 < diff2 ? 0 : 1;
1454                         fi = fis[point];
1455                         sin_fi = sin_fis[point];
1456                         cos_fi = cos_fis[point];
1457                         hook_tip_body(1) = hook_root_body(1) - hook_length * cos_fi;
1458                         hook_tip_body(3) = hook_root_body(3) + hook_length * sin_fi;
1459                     }
1460                 }
1461             }
1462         }
1463     } else {
1464         FGColumnVector3 hook_root_vel = Propagate->GetVel() + (Tb2l * (Propagate->GetPQR() *  hook_root_body));
1465         double wire_ends_ec[2][3];
1466         double wire_vel_ec[2][3];
1467         get_wire_ends_ft(t_off, wire_ends_ec, wire_vel_ec);
1468         FGColumnVector3 wire_vel_1 = Tec2l * FGColumnVector3(wire_vel_ec[0][0], wire_vel_ec[0][1], wire_vel_ec[0][2]);
1469         FGColumnVector3 wire_vel_2 = Tec2l * FGColumnVector3(wire_vel_ec[1][0], wire_vel_ec[1][1], wire_vel_ec[1][2]);
1470         FGColumnVector3 rel_vel = hook_root_vel - (wire_vel_1 + wire_vel_2) / 2;
1471         if (rel_vel.Magnitude() < 3) {
1472             got_wire = false;
1473             release_wire();
1474             fgSetDouble("/fdm/jsbsim/external_reactions/hook/magnitude", 0.0);
1475         } else {
1476             FGColumnVector3 wire_end1_body = Tl2b * Location.LocationToLocal(FGColumnVector3(wire_ends_ec[0][0], wire_ends_ec[0][1], wire_ends_ec[0][2])) - hook_root_body;
1477             FGColumnVector3 wire_end2_body = Tl2b * Location.LocationToLocal(FGColumnVector3(wire_ends_ec[1][0], wire_ends_ec[1][1], wire_ends_ec[1][2])) - hook_root_body;
1478             FGColumnVector3 force_plane_normal = wire_end1_body * wire_end2_body;
1479             force_plane_normal.Normalize();
1480             cos_fi = DotProduct(force_plane_normal, FGColumnVector3(0, 0, 1));
1481             if (cos_fi < 0) cos_fi = -cos_fi;
1482             sin_fi = sqrt(1 - sqr(cos_fi));
1483             fi = atan2(sin_fi, cos_fi) * SG_RADIANS_TO_DEGREES;
1484
1485             fgSetDouble("/fdm/jsbsim/external_reactions/hook/x", -cos_fi);
1486             fgSetDouble("/fdm/jsbsim/external_reactions/hook/y", 0);
1487             fgSetDouble("/fdm/jsbsim/external_reactions/hook/z", sin_fi);
1488             fgSetDouble("/fdm/jsbsim/external_reactions/hook/magnitude", fgGetDouble("/fdm/jsbsim/systems/hook/force"));
1489         }
1490     }
1491
1492     FGColumnVector3 hook_tip = Location.LocalToLocation(Tb2l * hook_tip_body);
1493
1494     hook_area[0][0] = hook_tip(1);
1495     hook_area[0][1] = hook_tip(2);
1496     hook_area[0][2] = hook_tip(3);
1497
1498     if (!got_wire) {
1499         // The previous positions.
1500         hook_area[2][0] = last_hook_root[0];
1501         hook_area[2][1] = last_hook_root[1];
1502         hook_area[2][2] = last_hook_root[2];
1503         hook_area[3][0] = last_hook_tip[0];
1504         hook_area[3][1] = last_hook_tip[1];
1505         hook_area[3][2] = last_hook_tip[2];
1506
1507         // Check if we caught a wire.
1508         // Returns true if we caught one.
1509         if (caught_wire_ft(t_off, hook_area)) {
1510                 got_wire = true;
1511         }
1512     }
1513
1514     // save actual position as old position ...
1515     last_hook_tip[0] = hook_area[0][0];
1516     last_hook_tip[1] = hook_area[0][1];
1517     last_hook_tip[2] = hook_area[0][2];
1518     last_hook_root[0] = hook_area[1][0];
1519     last_hook_root[1] = hook_area[1][1];
1520     last_hook_root[2] = hook_area[1][2];
1521
1522     fgSetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-deg", fi);
1523 }
1524