src/AIModel/AIShip.cxx

   1 // FGAIShip - FGAIBase-derived class creates an AI ship
   2 //
   3 // Written by David Culp, started October 2003.
   4 // with major amendments and additions by Vivian Meazza, 2004 - 2007
   5 //
   6 // This program is free software; you can redistribute it and/or
   7 // modify it under the terms of the GNU General Public License as
   8 // published by the Free Software Foundation; either version 2 of the
   9 // License, or (at your option) any later version.
  10 //
  11 // This program is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // General Public License for more details.
  15 //
  16 // You should have received a copy of the GNU General Public License
  17 // along with this program; if not, write to the Free Software
  18 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  19
  20 #ifdef HAVE_CONFIG_H
  21 #  include <config.h>
  22 #endif
  23
  24 #ifdef _MSC_VER
  25 #  include <float.h>
  26 #  define finite _finite
  27 #elif defined(__sun) || defined(sgi)
  28 #  include <ieeefp.h>
  29 #endif
  30
  31 #include <math.h>
  32 #include <simgear/math/sg_geodesy.hxx>
  33 #include <simgear/timing/sg_time.hxx>
  34 #include <simgear/math/sg_random.h>
  35
  36 #include "AIShip.hxx"
  37
  38
  39 FGAIShip::FGAIShip(object_type ot) :
  40     FGAIBase(ot),
  41     _dt_count(0),
  42     _next_run(0)
  43 {
  44 }
  45
  46 FGAIShip::~FGAIShip() {
  47 }
  48
  49 void FGAIShip::readFromScenario(SGPropertyNode* scFileNode) {
  50
  51     if (!scFileNode)
  52         return;
  53
  54     FGAIBase::readFromScenario(scFileNode);
  55
  56     setRudder(scFileNode->getFloatValue("rudder", 0.0));
  57     setName(scFileNode->getStringValue("name", "Titanic"));
  58     setRadius(scFileNode->getDoubleValue("turn-radius-ft", 2000));
  59     std::string flightplan = scFileNode->getStringValue("flightplan");
  60     setRepeat(scFileNode->getBoolValue("repeat", false));
  61     setStartTime(scFileNode->getStringValue("time", ""));
  62
  63     if (!flightplan.empty()) {
  64         FGAIFlightPlan* fp = new FGAIFlightPlan(flightplan);
  65         setFlightPlan(fp);
  66     }
  67
  68 }
  69
  70 bool FGAIShip::init(bool search_in_AI_path) {
  71     prev = 0; // the one behind you
  72     curr = 0; // the one ahead
  73     next = 0; // the next plus 1
  74
  75     _until_time = "";
  76
  77     props->setStringValue("name", _name.c_str());
  78     props->setStringValue("position/waypoint-name-prev", _prev_name.c_str());
  79     props->setStringValue("position/waypoint-name-curr", _curr_name.c_str());
  80     props->setStringValue("position/waypoint-name-next", _next_name.c_str());
  81     props->setStringValue("submodels/path", _path.c_str());
  82     props->setStringValue("position/waypoint-start-time", _start_time.c_str());
  83     props->setStringValue("position/waypoint-wait-until-time", _until_time.c_str());
  84
  85     _hdg_lock = false;
  86     _rudder = 0.0;
  87     no_roll = false;
  88
  89     _rudder_constant = 0.5;
  90     _roll_constant = 0.001;
  91     _speed_constant = 0.05;
  92     _hdg_constant = 0.01;
  93     _roll_factor = -0.0083335;
  94
  95     _rd_turn_radius_ft = _sp_turn_radius_ft = turn_radius_ft;
  96
  97     _fp_init = false;
  98     _missed = false;
  99     _waiting = false;
 100     _new_waypoint = true;
 101
 102     _missed_count = 0;
 103     _wait_count = 0;
 104     _missed_time_sec = 30;
 105
 106     _day = 86400;
 107
 108
 109     _wp_range = _old_range = 0;
 110     _range_rate = 0;
 111
 112     if (fp)
 113         _fp_init = initFlightPlan();
 114
 115     return FGAIBase::init(search_in_AI_path);
 116 }
 117
 118
 119 void FGAIShip::bind() {
 120     FGAIBase::bind();
 121
 122     props->tie("surface-positions/rudder-pos-deg",
 123         SGRawValuePointer<float>(&_rudder));
 124     props->tie("controls/heading-lock",
 125         SGRawValuePointer<bool>(&_hdg_lock));
 126     props->tie("controls/tgt-speed-kts",
 127         SGRawValuePointer<double>(&tgt_speed));
 128     props->tie("controls/tgt-heading-degs",
 129         SGRawValuePointer<double>(&tgt_heading));
 130     props->tie("controls/constants/rudder",
 131         SGRawValuePointer<double>(&_rudder_constant));
 132     props->tie("controls/constants/roll-factor",
 133         SGRawValuePointer<double>(&_roll_factor));
 134     props->tie("controls/constants/roll",
 135         SGRawValuePointer<double>(&_roll_constant));
 136     props->tie("controls/constants/rudder",
 137         SGRawValuePointer<double>(&_rudder_constant));
 138     props->tie("controls/constants/speed",
 139         SGRawValuePointer<double>(&_speed_constant));
 140     props->tie("position/waypoint-range-nm",
 141         SGRawValuePointer<double>(&_wp_range));
 142     props->tie("position/waypoint-range-old-nm",
 143         SGRawValuePointer<double>(&_old_range));
 144     props->tie("position/waypoint-range-rate-nm-sec",
 145         SGRawValuePointer<double>(&_range_rate));
 146     props->tie("position/waypoint-new",
 147         SGRawValuePointer<bool>(&_new_waypoint));
 148     props->tie("position/waypoint-missed",
 149         SGRawValuePointer<bool>(&_missed));
 150     props->tie("position/waypoint-missed-count",
 151         SGRawValuePointer<double>(&_missed_count));
 152     props->tie("position/waypoint-missed-time-sec",
 153         SGRawValuePointer<double>(&_missed_time_sec));
 154     props->tie("position/waypoint-wait-count",
 155         SGRawValuePointer<double>(&_wait_count));
 156     props->tie("position/waypoint-waiting",
 157         SGRawValuePointer<bool>(&_waiting));
 158     props->tie("submodels/serviceable",
 159         SGRawValuePointer<bool>(&_serviceable));
 160 }
 161
 162 void FGAIShip::unbind() {
 163     FGAIBase::unbind();
 164     props->untie("surface-positions/rudder-pos-deg");
 165     props->untie("controls/heading-lock");
 166     props->untie("controls/tgt-speed-kts");
 167     props->untie("controls/tgt-heading-degs");
 168     props->untie("controls/constants/roll");
 169     props->untie("controls/constants/rudder");
 170     props->untie("controls/constants/roll-factor");
 171     props->untie("controls/constants/speed");
 172     props->untie("position/waypoint-range-nm");
 173     props->untie("position/waypoint-range-old-nm");
 174     props->untie("position/waypoint-range-rate-nm-sec");
 175     props->untie("position/waypoint-new");
 176     props->untie("position/waypoint-missed");
 177     props->untie("position/waypoint-missed-count");
 178     props->untie("position/waypoint-missed-time-sec");
 179     props->untie("position/waypoint-wait-count");
 180     props->untie("position/waypoint-waiting");
 181     props->untie("submodels/serviceable");
 182 }
 183
 184 void FGAIShip::update(double dt) {
 185     FGAIBase::update(dt);
 186     Run(dt);
 187     Transform();
 188 }
 189
 190 void FGAIShip::Run(double dt) {
 191     //cout << _name << " init: " << _fp_init << endl;
 192     if (_fp_init)
 193         ProcessFlightPlan(dt);
 194
 195     //    double speed_north_deg_sec;
 196     //    double speed_east_deg_sec;
 197     double alpha;
 198     double rudder_limit;
 199     double raw_roll;
 200
 201     // adjust speed
 202     double speed_diff = tgt_speed - speed;
 203
 204     if (fabs(speed_diff) > 0.1) {
 205
 206         if (speed_diff > 0.0)
 207             speed += _speed_constant * dt;
 208
 209         if (speed_diff < 0.0)
 210             speed -= _speed_constant * dt;
 211
 212     }
 213
 214     // do not allow unreasonable ship speeds
 215     if (speed > 40)
 216         speed = 40;
 217
 218     // convert speed to degrees per second
 219     speed_north_deg_sec = cos(hdg / SGD_RADIANS_TO_DEGREES)
 220         * speed * 1.686 / ft_per_deg_lat;
 221     speed_east_deg_sec = sin(hdg / SGD_RADIANS_TO_DEGREES)
 222         * speed * 1.686 / ft_per_deg_lon;
 223
 224     // set new position
 225     pos.setLatitudeDeg(pos.getLatitudeDeg() + speed_north_deg_sec * dt);
 226     pos.setLongitudeDeg(pos.getLongitudeDeg() + speed_east_deg_sec * dt);
 227
 228     // adjust heading based on current _rudder angle
 229
 230     //cout << "turn_radius_ft " << turn_radius_ft ;
 231
 232     if (turn_radius_ft <= 0)
 233         turn_radius_ft = 0; // don't allow nonsense values
 234
 235     if (_rudder > 45)
 236         _rudder = 45;
 237
 238     if (_rudder < -45)
 239         _rudder = -45;
 240
 241     //we assume that at slow speed ships will manoeuvre using engines/bow thruster
 242     if (fabs(speed)<=5)
 243         _sp_turn_radius_ft = 500;
 244     else
 245         // adjust turn radius for speed. The equation is very approximate.
 246         // we need to allow for negative speeds
 247         _sp_turn_radius_ft = 10 * pow ((fabs(speed) - 15), 2) + turn_radius_ft;
 248
 249     //cout << " speed turn radius " << _sp_turn_radius_ft ;
 250
 251     if (_rudder <= -0.25 || _rudder >= 0.25) {
 252         // adjust turn radius for _rudder angle. The equation is even more approximate.
 253         float a = 19;
 254         float b = -0.2485;
 255         float c = 0.543;
 256
 257         _rd_turn_radius_ft = (a * exp(b * fabs(_rudder)) + c) * _sp_turn_radius_ft;
 258
 259         //cout <<" _rudder turn radius " << _rd_turn_radius_ft << endl;
 260
 261         // calculate the angle, alpha, subtended by the arc traversed in time dt
 262         alpha = ((speed * 1.686 * dt) / _rd_turn_radius_ft) * SG_RADIANS_TO_DEGREES;
 263
 264         // make sure that alpha is applied in the right direction
 265         hdg += alpha * sign(_rudder);
 266
 267         if (hdg > 360.0)
 268             hdg -= 360.0;
 269
 270         if (hdg < 0.0)
 271             hdg += 360.0;
 272
 273         //adjust roll for rudder angle and speed. Another bit of voodoo
 274         raw_roll = _roll_factor * speed * _rudder;
 275     } else {
 276         // _rudder angle is 0
 277         raw_roll = 0;
 278     }
 279
 280     //low pass filter
 281     if (speed < 0)
 282         roll = -roll;
 283
 284     roll = (raw_roll * _roll_constant) + (roll * (1 - _roll_constant));
 285
 286     // adjust target _rudder angle if heading lock engaged
 287     double rudder_diff = 0.0;
 288     if (_hdg_lock) {
 289         double rudder_sense = 0.0;
 290         double diff = fabs(hdg - tgt_heading);
 291         //cout << "_rudder diff" << diff << endl;
 292         if (diff > 180)
 293             diff = fabs(diff - 360);
 294
 295         double sum = hdg + diff;
 296
 297         if (sum > 360.0)
 298             sum -= 360.0;
 299
 300         if (fabs(sum - tgt_heading)< 1.0)
 301             rudder_sense = 1.0;
 302         else
 303             rudder_sense = -1.0;
 304
 305         if (speed < 0)
 306             rudder_sense = -rudder_sense;
 307
 308         if (diff < 15)
 309             _tgt_rudder = diff * rudder_sense;
 310         else
 311             _tgt_rudder = 45 * rudder_sense;
 312
 313         rudder_diff = _tgt_rudder - _rudder;
 314     }
 315
 316     // set the _rudder limit by speed
 317     if (speed <= 40)
 318         rudder_limit = (-0.825 * speed) + 35;
 319     else
 320         rudder_limit = 2;
 321
 322     if (fabs(rudder_diff)> 0.1) { // apply dead zone
 323
 324         if (rudder_diff > 0.0) {
 325             _rudder += _rudder_constant * dt;
 326
 327             if (_rudder > rudder_limit) // apply the _rudder limit
 328                 _rudder = rudder_limit;
 329
 330         } else if (rudder_diff < 0.0) {
 331             _rudder -= _rudder_constant * dt;
 332
 333             if (_rudder < -rudder_limit)
 334                 _rudder = -rudder_limit;
 335
 336         }
 337
 338         // do calculations for radar
 339         UpdateRadar(manager);
 340     }
 341 }//end function
 342
 343 void FGAIShip::AccelTo(double speed) {
 344     tgt_speed = speed;
 345 }
 346
 347 void FGAIShip::PitchTo(double angle) {
 348     tgt_pitch = angle;
 349 }
 350
 351 void FGAIShip::RollTo(double angle) {
 352     tgt_roll = angle;
 353 }
 354
 355 void FGAIShip::YawTo(double angle) {
 356 }
 357
 358 void FGAIShip::ClimbTo(double altitude) {
 359 }
 360
 361
 362 void FGAIShip::TurnTo(double heading) {
 363     tgt_heading = heading;
 364     _hdg_lock = true;
 365 }
 366
 367 double FGAIShip::sign(double x) {
 368     if (x < 0.0)
 369         return -1.0;
 370     else
 371         return 1.0;
 372 }
 373
 374 void FGAIShip::setFlightPlan(FGAIFlightPlan* f) {
 375     fp = f;
 376 }
 377
 378 void FGAIShip::setName(const string& n) {
 379     _name = n;
 380 }
 381
 382 void FGAIShip::setStartTime(const string& st) {
 383     _start_time = st;
 384 }
 385
 386 void FGAIShip::setUntilTime(const string& ut) {
 387     _until_time = ut;
 388     props->setStringValue("position/waypoint-wait-until-time", _until_time.c_str());
 389 }
 390
 391 void FGAIShip::setCurrName(const string& c) {
 392     _curr_name = c;
 393     props->setStringValue("position/waypoint-name-curr", _curr_name.c_str());
 394 }
 395
 396 void FGAIShip::setNextName(const string& n) {
 397     _next_name = n;
 398     props->setStringValue("position/waypoint-name-next", _next_name.c_str());
 399 }
 400
 401 void FGAIShip::setPrevName(const string& p) {
 402     _prev_name = p;
 403     props->setStringValue("position/waypoint-name-prev", _prev_name.c_str());
 404 }
 405
 406 void FGAIShip::setRepeat(bool r) {
 407     _repeat = r;
 408 }
 409
 410 void FGAIShip::setMissed(bool m) {
 411     _missed = m;
 412     props->setBoolValue("position/waypoint-missed", _missed);
 413 }
 414
 415 void FGAIShip::setRudder(float r) {
 416     _rudder = r;
 417 }
 418
 419 void FGAIShip::setRoll(double rl) {
 420     roll = rl;
 421 }
 422
 423 void FGAIShip::setWPNames() {
 424
 425     if (prev != 0)
 426         setPrevName(prev->name);
 427     else
 428         setPrevName("");
 429
 430     setCurrName(curr->name);
 431
 432     if (next != 0)
 433         setNextName(next->name);
 434     else
 435         setNextName("");
 436
 437     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: prev wp name " << prev->name);
 438     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: current wp name " << curr->name);
 439     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: next wp name " << next->name);
 440
 441 }
 442
 443 double FGAIShip::getRange(double lat, double lon, double lat2, double lon2) const {
 444
 445     double course, distance, az2;
 446
 447     //calculate the bearing and range of the second pos from the first
 448     geo_inverse_wgs_84(lat, lon, lat2, lon2, &course, &az2, &distance);
 449     distance *= SG_METER_TO_NM;
 450     return distance;
 451 }
 452
 453 double FGAIShip::getCourse(double lat, double lon, double lat2, double lon2) const {
 454
 455     double course, distance, recip;
 456
 457     //calculate the bearing and range of the second pos from the first
 458     geo_inverse_wgs_84(lat, lon, lat2, lon2, &course, &recip, &distance);
 459     if (tgt_speed >= 0) {
 460         return course;
 461     } else {
 462         return recip;
 463     }
 464 }
 465
 466 void FGAIShip::ProcessFlightPlan(double dt) {
 467
 468     double time_sec = getDaySeconds();
 469     double until_time_sec = 0;
 470
 471     _missed = false;
 472     _dt_count += dt;
 473
 474     ///////////////////////////////////////////////////////////////////////////
 475     // Check Execution time (currently once every 1 sec)
 476     // Add a bit of randomization to prevent the execution of all flight plans
 477     // in synchrony, which can add significant periodic framerate flutter.
 478     ///////////////////////////////////////////////////////////////////////////
 479
 480     //cout << "_start_sec " << _start_sec << " time_sec " << time_sec << endl;
 481     if (_dt_count < _next_run && _start_sec < time_sec)
 482         return;
 483
 484     _next_run = 1.0 + (0.5 * sg_random());
 485
 486     // check to see if we've reached the point for our next turn
 487     // if the range to the waypoint is less than the calculated turn
 488     // radius we can start the turn to the next leg
 489     _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 490     _range_rate = (_wp_range - _old_range) / _dt_count;
 491     double sp_turn_radius_nm = _sp_turn_radius_ft / 6076.1155;
 492
 493     // we need to try to identify a _missed waypoint
 494
 495     // calculate the time needed to turn through an arc of 90 degrees, and allow an error of 30 secs
 496     if (speed != 0)
 497         _missed_time_sec = 30 + ((SGD_PI * sp_turn_radius_nm * 60 * 60) / (2 * fabs(speed)));
 498     else
 499         _missed_time_sec = 30;
 500
 501     if ((_range_rate > 0) && (_wp_range < 3 * sp_turn_radius_nm) && !_new_waypoint)
 502         _missed_count += _dt_count;
 503
 504     if (_missed_count >= _missed_time_sec) {
 505         setMissed(true);
 506     } else {
 507         setMissed(false);
 508     }
 509
 510     _old_range = _wp_range;
 511     setWPNames();
 512
 513     if ((_wp_range < sp_turn_radius_nm) || _missed || _waiting && !_new_waypoint) {
 514
 515         if (_next_name == "END") {
 516
 517             if (_repeat) {
 518                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Flightplan restarting ");
 519                 fp->restart();
 520                 prev = curr;
 521                 curr = fp->getCurrentWaypoint();
 522                 next = fp->getNextWaypoint();
 523                 setWPNames();
 524                 _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 525                 _old_range = _wp_range;
 526                 _range_rate = 0;
 527                 _new_waypoint = true;
 528                 _missed_count = 0;
 529                 AccelTo(prev->speed);
 530             } else {
 531                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Flightplan dieing ");
 532                 setDie(true);
 533                 _dt_count = 0;
 534                 return;
 535             }
 536
 537         } else if (_next_name == "WAIT") {
 538
 539             if (_wait_count < next->time_sec) {
 540                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " waiting ");
 541                 setSpeed(0);
 542                 _waiting = true;
 543                 _wait_count += _dt_count;
 544                 _dt_count = 0;
 545                 return;
 546             } else {
 547                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name
 548                     << " wait done: getting new waypoints ");
 549                 _waiting = false;
 550                 _wait_count = 0;
 551                 fp->IncrementWaypoint(false);
 552                 next = fp->getNextWaypoint();
 553
 554                 if (next->name == "WAITUNTIL" || next->name == "WAIT"
 555                         || next->name == "END")
 556                     return;
 557
 558                 prev = curr;
 559                 fp->IncrementWaypoint(false);
 560                 curr = fp->getCurrentWaypoint();
 561                 next = fp->getNextWaypoint();
 562             }
 563
 564         } else if (_next_name == "WAITUNTIL") {
 565             time_sec = getDaySeconds();
 566             until_time_sec = processTimeString(next->time);
 567             _until_time = next->time;
 568             setUntilTime(next->time);
 569             if (until_time_sec > time_sec) {
 570                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " waiting until: "
 571                     << _until_time << " " << until_time_sec << " now " << time_sec );
 572                 setSpeed(0);
 573                 _waiting = true;
 574                 return;
 575             } else {
 576                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: "
 577                     << _name << " wait until done: getting new waypoints ");
 578                 setUntilTime("");
 579                 fp->IncrementWaypoint(false);
 580
 581                 while (next->name == "WAITUNTIL") {
 582                     fp->IncrementWaypoint(false);
 583                     next = fp->getNextWaypoint();
 584                 }
 585
 586                 if (next->name == "WAIT")
 587                     return;
 588
 589                 prev = curr;
 590                 fp->IncrementWaypoint(false);
 591                 curr = fp->getCurrentWaypoint();
 592                 next = fp->getNextWaypoint();
 593                 _waiting = false;
 594             }
 595
 596         } else {
 597             //now reorganise the waypoints, so that next becomes current and so on
 598             SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " getting new waypoints ");
 599             fp->IncrementWaypoint(false);
 600             prev = fp->getPreviousWaypoint(); //first waypoint
 601             curr = fp->getCurrentWaypoint();  //second waypoint
 602             next = fp->getNextWaypoint();     //third waypoint (might not exist!)
 603         }
 604
 605         setWPNames();
 606         _new_waypoint = true;
 607         _missed_count = 0;
 608         _range_rate = 0;
 609         _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 610         _old_range = _wp_range;
 611         AccelTo(prev->speed);
 612     } else {
 613         _new_waypoint = false;
 614     }
 615
 616     //   now revise the required course for the next way point
 617     double course = getCourse(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 618
 619     if (finite(course))
 620         TurnTo(course);
 621     else
 622         SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Bearing or Range is not a finite number");
 623
 624      _dt_count = 0;
 625 } // end Processing FlightPlan
 626
 627 bool FGAIShip::initFlightPlan() {
 628
 629     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " initializing waypoints ");
 630
 631     bool init = false;
 632
 633     _start_sec = 0;
 634
 635     fp->restart();
 636     fp->IncrementWaypoint(false);
 637
 638     prev = fp->getPreviousWaypoint(); //first waypoint
 639     curr = fp->getCurrentWaypoint();  //second waypoint
 640     next = fp->getNextWaypoint();     //third waypoint (might not exist!)
 641
 642     while (curr->name == "WAIT" || curr->name == "WAITUNTIL") {  // don't wait when initialising
 643         SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " re-initializing waypoints ");
 644         fp->IncrementWaypoint(false);
 645         curr = fp->getCurrentWaypoint();
 646         next = fp->getNextWaypoint();
 647     }
 648
 649     if (!_start_time.empty()){
 650         _start_sec = processTimeString(_start_time);
 651         double day_sec = getDaySeconds();
 652
 653         if (_start_sec < day_sec){
 654             //cout << "flight plan has already started " << _start_time << endl;
 655             init = advanceFlightPlan(_start_sec, day_sec);
 656
 657         } else if (_start_sec > day_sec && _repeat) {
 658             //cout << "flight plan has not started, " << _start_time;
 659             //cout << "offsetting start time by -24 hrs" << endl;
 660             _start_sec -= _day;
 661             init = advanceFlightPlan(_start_sec, day_sec);
 662         }
 663
 664         if (init)
 665             _start_sec = 0; // set to zero for an immediate start of the Flight Plan
 666         else {
 667             fp->restart();
 668             fp->IncrementWaypoint(false);
 669             prev = fp->getPreviousWaypoint();
 670             curr = fp->getCurrentWaypoint();
 671             next = fp->getNextWaypoint();
 672             return false;
 673         }
 674
 675     } else {
 676     setLatitude(prev->latitude);
 677     setLongitude(prev->longitude);
 678     setSpeed(prev->speed);
 679     }
 680
 681     setWPNames();
 682     setHeading(getCourse(prev->latitude, prev->longitude, curr->latitude, curr->longitude));
 683     _wp_range = getRange(prev->latitude, prev->longitude, curr->latitude, curr->longitude);
 684     _old_range = _wp_range;
 685     _range_rate = 0;
 686     _hdg_lock = true;
 687     _missed = false;
 688     _missed_count = 0;
 689     _new_waypoint = true;
 690
 691     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " done initialising waypoints ");
 692     if (prev)
 693         init = true;
 694
 695     if (init)
 696         return true;
 697     else
 698         return false;
 699
 700 } // end of initialization
 701
 702
 703 double FGAIShip::processTimeString(const string& theTime) {
 704
 705     int Hour;
 706     int Minute;
 707     int Second;
 708
 709     // first split theTime string into
 710     //  hour, minute, second and convert to int;
 711     Hour   = atoi(theTime.substr(0,2).c_str());
 712     Minute = atoi(theTime.substr(3,5).c_str());
 713     Second = atoi(theTime.substr(6,8).c_str());
 714
 715     // offset by a day-sec to allow for starting a day earlier
 716     double time_seconds = Hour * 3600
 717         + Minute * 60
 718         + Second;
 719
 720     return time_seconds;
 721 }
 722
 723 double FGAIShip::getDaySeconds () {
 724     // Date and time
 725     struct tm *t = globals->get_time_params()->getGmt();
 726
 727     double day_seconds = t->tm_hour * 3600
 728         + t->tm_min * 60
 729         + t->tm_sec;
 730
 731     return day_seconds;
 732 }
 733
 734 bool FGAIShip::advanceFlightPlan (double start_sec, double day_sec) {
 735
 736     double elapsed_sec = start_sec;
 737     double distance_nm = 0;
 738
 739     //cout << "advancing flight plan start_sec: " << start_sec << " " << day_sec << endl;
 740
 741     while ( elapsed_sec < day_sec ) {
 742
 743         if (next->name == "END") {
 744
 745             if (_repeat ) {
 746                 //cout << _name << ": " << "restarting flightplan" << endl;
 747                 fp->restart();
 748                 curr = fp->getCurrentWaypoint();
 749                 next = fp->getNextWaypoint();
 750             } else {
 751                 //cout << _name << ": " << "ending flightplan" << endl;
 752                 setDie(true);
 753                 return false;
 754             }
 755
 756         } else if (next->name == "WAIT") {
 757             //cout << _name << ": begin WAIT: " << prev->name << " ";
 758             //cout << curr->name << " " << next->name << endl;
 759
 760             elapsed_sec += next->time_sec;
 761
 762             if ( elapsed_sec >= day_sec)
 763                 continue;
 764
 765             fp->IncrementWaypoint(false);
 766             next = fp->getNextWaypoint();
 767
 768             if (next->name != "WAITUNTIL" && next->name != "WAIT"
 769                     && next->name != "END") {
 770                 prev = curr;
 771                 fp->IncrementWaypoint(false);
 772                 curr = fp->getCurrentWaypoint();
 773                 next = fp->getNextWaypoint();
 774             }
 775
 776         } else if (next->name == "WAITUNTIL") {
 777             double until_sec = processTimeString(next->time);
 778
 779             if (until_sec > _start_sec && start_sec < 0)
 780                 until_sec -= _day;
 781
 782             if (elapsed_sec < until_sec)
 783                 elapsed_sec = until_sec;
 784
 785             if (elapsed_sec >= day_sec )
 786                 break;
 787
 788             fp->IncrementWaypoint(false);
 789             next = fp->getNextWaypoint();
 790
 791             if (next->name != "WAITUNTIL" && next->name != "WAIT") {
 792                 prev = curr;
 793                 fp->IncrementWaypoint(false);
 794                 curr = fp->getCurrentWaypoint();
 795                 next = fp->getNextWaypoint();
 796             }
 797
 798             //cout << _name << ": end WAITUNTIL: ";
 799             //cout << prev->name << " " << curr->name << " " << next->name <<  endl;
 800
 801         } else {
 802             distance_nm = getRange(prev->latitude, prev->longitude, curr->latitude, curr->longitude);
 803             elapsed_sec += distance_nm * 60 * 60 / prev->speed;
 804
 805             if (elapsed_sec >= day_sec)
 806                 continue;
 807
 808             fp->IncrementWaypoint(false);
 809             prev = fp->getPreviousWaypoint();
 810             curr = fp->getCurrentWaypoint();
 811             next = fp->getNextWaypoint();
 812         }
 813
 814     }   // end while
 815
 816     // the required position lies between the previous and current waypoints
 817     // so we will calculate the distance back up the track from the current waypoint
 818     // then calculate the lat and lon.
 819     /*cout << "advancing flight plan done elapsed_sec: " << elapsed_sec
 820         << " " << day_sec << endl;*/
 821
 822     double time_diff = elapsed_sec - day_sec;
 823     double lat, lon, recip;
 824
 825     //cout << " time diff " << time_diff << endl;
 826
 827     if (next->name == "WAIT" ){
 828         setSpeed(0);
 829         lat = curr->latitude;
 830         lon = curr->longitude;
 831         _wait_count= time_diff;
 832         _waiting = true;
 833     } else if (next->name == "WAITUNTIL") {
 834         setSpeed(0);
 835         lat = curr->latitude;
 836         lon = curr->longitude;
 837         _waiting = true;
 838     } else {
 839         setSpeed(prev->speed);
 840         distance_nm = speed * time_diff / (60 * 60);
 841         double brg = getCourse(curr->latitude, curr->longitude, prev->latitude, prev->longitude);
 842
 843         //cout << " brg " << brg << " from " << curr->name << " to " << prev->name << " "
 844         //    << " lat "  << curr->latitude << " lon " << curr->longitude
 845         //    << " distance m " << distance_nm * SG_NM_TO_METER << endl;
 846
 847         lat = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 848             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 849         lon = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 850             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 851         recip = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 852             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 853     }
 854
 855     //cout << "Pos " << lat << ", " << lon << " recip " << recip << endl;
 856
 857     setLatitude(lat);
 858     setLongitude(lon);
 859     return true;
 860 }