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-wait-count");
 178     props->untie("position/waypoint-waiting");
 179     props->untie("position/waypoint-missed-time-sec");
 180     props->untie("submodels/serviceable");
 181 }
 182
 183 void FGAIShip::update(double dt) {
 184     FGAIBase::update(dt);
 185     Run(dt);
 186     Transform();
 187 }
 188
 189 void FGAIShip::Run(double dt) {
 190     //cout << _name << " init: " << _fp_init << endl;
 191     if (_fp_init)
 192         ProcessFlightPlan(dt);
 193
 194     //    double speed_north_deg_sec;
 195     //    double speed_east_deg_sec;
 196     double alpha;
 197     double rudder_limit;
 198     double raw_roll;
 199
 200     // adjust speed
 201     double speed_diff = tgt_speed - speed;
 202
 203     if (fabs(speed_diff) > 0.1) {
 204
 205         if (speed_diff > 0.0)
 206             speed += _speed_constant * dt;
 207
 208         if (speed_diff < 0.0)
 209             speed -= _speed_constant * dt;
 210
 211     }
 212
 213     // do not allow unreasonable ship speeds
 214     if (speed > 40)
 215         speed = 40;
 216
 217     // convert speed to degrees per second
 218     speed_north_deg_sec = cos(hdg / SGD_RADIANS_TO_DEGREES)
 219         * speed * 1.686 / ft_per_deg_lat;
 220     speed_east_deg_sec = sin(hdg / SGD_RADIANS_TO_DEGREES)
 221         * speed * 1.686 / ft_per_deg_lon;
 222
 223     // set new position
 224     pos.setLatitudeDeg(pos.getLatitudeDeg() + speed_north_deg_sec * dt);
 225     pos.setLongitudeDeg(pos.getLongitudeDeg() + speed_east_deg_sec * dt);
 226
 227     // adjust heading based on current _rudder angle
 228
 229     //cout << "turn_radius_ft " << turn_radius_ft ;
 230
 231     if (turn_radius_ft <= 0)
 232         turn_radius_ft = 0; // don't allow nonsense values
 233
 234     if (_rudder > 45)
 235         _rudder = 45;
 236
 237     if (_rudder < -45)
 238         _rudder = -45;
 239
 240     //we assume that at slow speed ships will manoeuvre using engines/bow thruster
 241     if (fabs(speed)<=5)
 242         _sp_turn_radius_ft = 500;
 243     else
 244         // adjust turn radius for speed. The equation is very approximate.
 245         // we need to allow for negative speeds
 246         _sp_turn_radius_ft = 10 * pow ((fabs(speed) - 15), 2) + turn_radius_ft;
 247
 248     //cout << " speed turn radius " << _sp_turn_radius_ft ;
 249
 250     if (_rudder <= -0.25 || _rudder >= 0.25) {
 251         // adjust turn radius for _rudder angle. The equation is even more approximate.
 252         float a = 19;
 253         float b = -0.2485;
 254         float c = 0.543;
 255
 256         _rd_turn_radius_ft = (a * exp(b * fabs(_rudder)) + c) * _sp_turn_radius_ft;
 257
 258         //cout <<" _rudder turn radius " << _rd_turn_radius_ft << endl;
 259
 260         // calculate the angle, alpha, subtended by the arc traversed in time dt
 261         alpha = ((speed * 1.686 * dt) / _rd_turn_radius_ft) * SG_RADIANS_TO_DEGREES;
 262
 263         // make sure that alpha is applied in the right direction
 264         hdg += alpha * sign(_rudder);
 265
 266         if (hdg > 360.0)
 267             hdg -= 360.0;
 268
 269         if (hdg < 0.0)
 270             hdg += 360.0;
 271
 272         //adjust roll for rudder angle and speed. Another bit of voodoo
 273         raw_roll = _roll_factor * speed * _rudder;
 274     } else {
 275         // _rudder angle is 0
 276         raw_roll = 0;
 277     }
 278
 279     //low pass filter
 280     if (speed < 0)
 281         roll = -roll;
 282
 283     roll = (raw_roll * _roll_constant) + (roll * (1 - _roll_constant));
 284
 285     // adjust target _rudder angle if heading lock engaged
 286     if (_hdg_lock) {
 287         double rudder_sense = 0.0;
 288         double diff = fabs(hdg - tgt_heading);
 289         //cout << "_rudder diff" << diff << endl;
 290         if (diff > 180)
 291             diff = fabs(diff - 360);
 292
 293         double sum = hdg + diff;
 294
 295         if (sum > 360.0)
 296             sum -= 360.0;
 297
 298         if (fabs(sum - tgt_heading)< 1.0)
 299             rudder_sense = 1.0;
 300         else
 301             rudder_sense = -1.0;
 302
 303         if (speed < 0)
 304             rudder_sense = -rudder_sense;
 305
 306         if (diff < 15)
 307             _tgt_rudder = diff * rudder_sense;
 308         else
 309             _tgt_rudder = 45 * rudder_sense;
 310     }
 311
 312     // adjust _rudder angle
 313     double rudder_diff = _tgt_rudder - _rudder;
 314
 315     // set the _rudder limit by speed
 316     if (speed <= 40)
 317         rudder_limit = (-0.825 * speed) + 35;
 318     else
 319         rudder_limit = 2;
 320
 321     if (fabs(rudder_diff)> 0.1) { // apply dead zone
 322
 323         if (rudder_diff > 0.0) {
 324             _rudder += _rudder_constant * dt;
 325
 326             if (_rudder > rudder_limit) // apply the _rudder limit
 327                 _rudder = rudder_limit;
 328
 329         } else if (rudder_diff < 0.0) {
 330             _rudder -= _rudder_constant * dt;
 331
 332             if (_rudder < -rudder_limit)
 333                 _rudder = -rudder_limit;
 334
 335         }
 336
 337         // do calculations for radar
 338         UpdateRadar(manager);
 339     }
 340 }//end function
 341
 342 void FGAIShip::AccelTo(double speed) {
 343     tgt_speed = speed;
 344 }
 345
 346 void FGAIShip::PitchTo(double angle) {
 347     tgt_pitch = angle;
 348 }
 349
 350 void FGAIShip::RollTo(double angle) {
 351     tgt_roll = angle;
 352 }
 353
 354 void FGAIShip::YawTo(double angle) {
 355 }
 356
 357 void FGAIShip::ClimbTo(double altitude) {
 358 }
 359
 360
 361 void FGAIShip::TurnTo(double heading) {
 362     tgt_heading = heading;
 363     _hdg_lock = true;
 364 }
 365
 366 double FGAIShip::sign(double x) {
 367     if (x < 0.0)
 368         return -1.0;
 369     else
 370         return 1.0;
 371 }
 372
 373 void FGAIShip::setFlightPlan(FGAIFlightPlan* f) {
 374     fp = f;
 375 }
 376
 377 void FGAIShip::setName(const string& n) {
 378     _name = n;
 379 }
 380
 381 void FGAIShip::setStartTime(const string& st) {
 382     _start_time = st;
 383 }
 384
 385 void FGAIShip::setUntilTime(const string& ut) {
 386     _until_time = ut;
 387     props->setStringValue("position/waypoint-wait-until-time", _until_time.c_str());
 388 }
 389
 390 void FGAIShip::setCurrName(const string& c) {
 391     _curr_name = c;
 392     props->setStringValue("position/waypoint-name-curr", _curr_name.c_str());
 393 }
 394
 395 void FGAIShip::setNextName(const string& n) {
 396     _next_name = n;
 397     props->setStringValue("position/waypoint-name-next", _next_name.c_str());
 398 }
 399
 400 void FGAIShip::setPrevName(const string& p) {
 401     _prev_name = p;
 402     props->setStringValue("position/waypoint-name-prev", _prev_name.c_str());
 403 }
 404
 405 void FGAIShip::setRepeat(bool r) {
 406     _repeat = r;
 407 }
 408
 409 void FGAIShip::setMissed(bool m) {
 410     _missed = m;
 411     props->setBoolValue("position/waypoint-missed", _missed);
 412 }
 413
 414 void FGAIShip::setRudder(float r) {
 415     _rudder = r;
 416 }
 417
 418 void FGAIShip::setRoll(double rl) {
 419     roll = rl;
 420 }
 421
 422 void FGAIShip::setWPNames() {
 423
 424     if (prev != 0)
 425         setPrevName(prev->name);
 426     else
 427         setPrevName("");
 428
 429     setCurrName(curr->name);
 430
 431     if (next != 0)
 432         setNextName(next->name);
 433     else
 434         setNextName("");
 435
 436     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: prev wp name " << prev->name);
 437     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: current wp name " << curr->name);
 438     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: next wp name " << next->name);
 439
 440 }
 441
 442 double FGAIShip::getRange(double lat, double lon, double lat2, double lon2) const {
 443
 444     double course, distance, az2;
 445
 446     //calculate the bearing and range of the second pos from the first
 447     geo_inverse_wgs_84(lat, lon, lat2, lon2, &course, &az2, &distance);
 448     distance *= SG_METER_TO_NM;
 449     return distance;
 450 }
 451
 452 double FGAIShip::getCourse(double lat, double lon, double lat2, double lon2) const {
 453
 454     double course, distance, recip;
 455
 456     //calculate the bearing and range of the second pos from the first
 457     geo_inverse_wgs_84(lat, lon, lat2, lon2, &course, &recip, &distance);
 458     if (tgt_speed >= 0) {
 459         return course;
 460     } else {
 461         return recip;
 462     }
 463 }
 464
 465 void FGAIShip::ProcessFlightPlan(double dt) {
 466
 467     double time_sec = getDaySeconds();
 468     double until_time_sec = 0;
 469
 470     _missed = false;
 471     _dt_count += dt;
 472
 473     ///////////////////////////////////////////////////////////////////////////
 474     // Check Execution time (currently once every 1 sec)
 475     // Add a bit of randomization to prevent the execution of all flight plans
 476     // in synchrony, which can add significant periodic framerate flutter.
 477     ///////////////////////////////////////////////////////////////////////////
 478
 479     //cout << "_start_sec " << _start_sec << " time_sec " << time_sec << endl;
 480     if (_dt_count < _next_run && _start_sec < time_sec)
 481         return;
 482
 483     _next_run = 1.0 + (0.5 * sg_random());
 484
 485     // check to see if we've reached the point for our next turn
 486     // if the range to the waypoint is less than the calculated turn
 487     // radius we can start the turn to the next leg
 488     _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 489     _range_rate = (_wp_range - _old_range) / _dt_count;
 490     double sp_turn_radius_nm = _sp_turn_radius_ft / 6076.1155;
 491
 492     // we need to try to identify a _missed waypoint
 493
 494     // calculate the time needed to turn through an arc of 90 degrees, and allow an error of 30 secs
 495     if (speed != 0)
 496         _missed_time_sec = 30 + ((SGD_PI * sp_turn_radius_nm * 60 * 60) / (2 * fabs(speed)));
 497     else
 498         _missed_time_sec = 30;
 499
 500     if ((_range_rate > 0) && (_wp_range < 3 * sp_turn_radius_nm) && !_new_waypoint)
 501         _missed_count += _dt_count;
 502
 503     if (_missed_count >= _missed_time_sec) {
 504         setMissed(true);
 505     } else {
 506         setMissed(false);
 507     }
 508
 509     _old_range = _wp_range;
 510     setWPNames();
 511
 512     if ((_wp_range < sp_turn_radius_nm) || _missed || _waiting && !_new_waypoint) {
 513
 514         if (_next_name == "END") {
 515
 516             if (_repeat) {
 517                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Flightplan restarting ");
 518                 fp->restart();
 519                 prev = curr;
 520                 curr = fp->getCurrentWaypoint();
 521                 next = fp->getNextWaypoint();
 522                 setWPNames();
 523                 _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 524                 _old_range = _wp_range;
 525                 _range_rate = 0;
 526                 _new_waypoint = true;
 527                 _missed_count = 0;
 528                 AccelTo(prev->speed);
 529             } else {
 530                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Flightplan dieing ");
 531                 setDie(true);
 532                 _dt_count = 0;
 533                 return;
 534             }
 535
 536         } else if (_next_name == "WAIT") {
 537
 538             if (_wait_count < next->time_sec) {
 539                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " waiting ");
 540                 setSpeed(0);
 541                 _waiting = true;
 542                 _wait_count += _dt_count;
 543                 _dt_count = 0;
 544                 return;
 545             } else {
 546                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name
 547                     << " wait done: getting new waypoints ");
 548                 _waiting = false;
 549                 _wait_count = 0;
 550                 fp->IncrementWaypoint(false);
 551                 next = fp->getNextWaypoint();
 552
 553                 if (next->name == "WAITUNTIL" || next->name == "WAIT"
 554                         || next->name == "END")
 555                     return;
 556
 557                 prev = curr;
 558                 fp->IncrementWaypoint(false);
 559                 curr = fp->getCurrentWaypoint();
 560                 next = fp->getNextWaypoint();
 561             }
 562
 563         } else if (_next_name == "WAITUNTIL") {
 564             time_sec = getDaySeconds();
 565             until_time_sec = processTimeString(next->time);
 566             _until_time = next->time;
 567             setUntilTime(next->time);
 568             if (until_time_sec > time_sec) {
 569                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " waiting until: "
 570                     << _until_time << " " << until_time_sec << " now " << time_sec );
 571                 setSpeed(0);
 572                 _waiting = true;
 573                 return;
 574             } else {
 575                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: "
 576                     << _name << " wait until done: getting new waypoints ");
 577                 setUntilTime("");
 578                 fp->IncrementWaypoint(false);
 579
 580                 while (next->name == "WAITUNTIL") {
 581                     fp->IncrementWaypoint(false);
 582                     next = fp->getNextWaypoint();
 583                 }
 584
 585                 if (next->name == "WAIT")
 586                     return;
 587
 588                 prev = curr;
 589                 fp->IncrementWaypoint(false);
 590                 curr = fp->getCurrentWaypoint();
 591                 next = fp->getNextWaypoint();
 592                 _waiting = false;
 593             }
 594
 595         } else {
 596             //now reorganise the waypoints, so that next becomes current and so on
 597             SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " getting new waypoints ");
 598             fp->IncrementWaypoint(false);
 599             prev = fp->getPreviousWaypoint(); //first waypoint
 600             curr = fp->getCurrentWaypoint();  //second waypoint
 601             next = fp->getNextWaypoint();     //third waypoint (might not exist!)
 602         }
 603
 604         setWPNames();
 605         _new_waypoint = true;
 606         _missed_count = 0;
 607         _range_rate = 0;
 608         _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 609         _old_range = _wp_range;
 610         AccelTo(prev->speed);
 611     } else {
 612         _new_waypoint = false;
 613     }
 614
 615     //   now revise the required course for the next way point
 616     double course = getCourse(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 617
 618     if (finite(course))
 619         TurnTo(course);
 620     else
 621         SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Bearing or Range is not a finite number");
 622
 623      _dt_count = 0;
 624 } // end Processing FlightPlan
 625
 626 bool FGAIShip::initFlightPlan() {
 627
 628     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " initializing waypoints ");
 629
 630     bool init = false;
 631
 632     _start_sec = 0;
 633
 634     fp->restart();
 635     fp->IncrementWaypoint(false);
 636
 637     prev = fp->getPreviousWaypoint(); //first waypoint
 638     curr = fp->getCurrentWaypoint();  //second waypoint
 639     next = fp->getNextWaypoint();     //third waypoint (might not exist!)
 640
 641     while (curr->name == "WAIT" || curr->name == "WAITUNTIL") {  // don't wait when initialising
 642         SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " re-initializing waypoints ");
 643         fp->IncrementWaypoint(false);
 644         curr = fp->getCurrentWaypoint();
 645         next = fp->getNextWaypoint();
 646     }
 647
 648     if (!_start_time.empty()){
 649         _start_sec = processTimeString(_start_time);
 650         double day_sec = getDaySeconds();
 651
 652         if (_start_sec < day_sec){
 653             //cout << "flight plan has already started " << _start_time << endl;
 654             init = advanceFlightPlan(_start_sec, day_sec);
 655
 656         } else if (_start_sec > day_sec && _repeat) {
 657             //cout << "flight plan has not started, " << _start_time;
 658             //cout << "offsetting start time by -24 hrs" << endl;
 659             _start_sec -= _day;
 660             init = advanceFlightPlan(_start_sec, day_sec);
 661         }
 662
 663         if (init)
 664             _start_sec = 0; // set to zero for an immediate start of the Flight Plan
 665         else {
 666             fp->restart();
 667             fp->IncrementWaypoint(false);
 668             prev = fp->getPreviousWaypoint();
 669             curr = fp->getCurrentWaypoint();
 670             next = fp->getNextWaypoint();
 671             return false;
 672         }
 673
 674     } else {
 675     setLatitude(prev->latitude);
 676     setLongitude(prev->longitude);
 677     setSpeed(prev->speed);
 678     }
 679
 680     setWPNames();
 681     setHeading(getCourse(prev->latitude, prev->longitude, curr->latitude, curr->longitude));
 682     _wp_range = getRange(prev->latitude, prev->longitude, curr->latitude, curr->longitude);
 683     _old_range = _wp_range;
 684     _range_rate = 0;
 685     _hdg_lock = true;
 686     _missed = false;
 687     _missed_count = 0;
 688     _new_waypoint = true;
 689
 690     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " done initialising waypoints ");
 691     if (prev)
 692         init = true;
 693
 694     if (init)
 695         return true;
 696     else
 697         return false;
 698
 699 } // end of initialization
 700
 701
 702 double FGAIShip::processTimeString(const string& theTime) {
 703
 704     int Hour;
 705     int Minute;
 706     int Second;
 707
 708     // first split theTime string into
 709     //  hour, minute, second and convert to int;
 710     Hour   = atoi(theTime.substr(0,2).c_str());
 711     Minute = atoi(theTime.substr(3,5).c_str());
 712     Second = atoi(theTime.substr(6,8).c_str());
 713
 714     // offset by a day-sec to allow for starting a day earlier
 715     double time_seconds = Hour * 3600
 716         + Minute * 60
 717         + Second;
 718
 719     return time_seconds;
 720 }
 721
 722 double FGAIShip::getDaySeconds () {
 723     // Date and time
 724     struct tm *t = globals->get_time_params()->getGmt();
 725
 726     double day_seconds = t->tm_hour * 3600
 727         + t->tm_min * 60
 728         + t->tm_sec;
 729
 730     return day_seconds;
 731 }
 732
 733 bool FGAIShip::advanceFlightPlan (double start_sec, double day_sec) {
 734
 735     double elapsed_sec = start_sec;
 736     double distance_nm = 0;
 737
 738     //cout << "advancing flight plan start_sec: " << start_sec << " " << day_sec << endl;
 739
 740     while ( elapsed_sec < day_sec ) {
 741
 742         if (next->name == "END") {
 743
 744             if (_repeat ) {
 745                 //cout << _name << ": " << "restarting flightplan" << endl;
 746                 fp->restart();
 747                 curr = fp->getCurrentWaypoint();
 748                 next = fp->getNextWaypoint();
 749             } else {
 750                 //cout << _name << ": " << "ending flightplan" << endl;
 751                 setDie(true);
 752                 return false;
 753             }
 754
 755         } else if (next->name == "WAIT") {
 756             //cout << _name << ": begin WAIT: " << prev->name << " ";
 757             //cout << curr->name << " " << next->name << endl;
 758
 759             elapsed_sec += next->time_sec;
 760
 761             if ( elapsed_sec >= day_sec)
 762                 continue;
 763
 764             fp->IncrementWaypoint(false);
 765             next = fp->getNextWaypoint();
 766
 767             if (next->name != "WAITUNTIL" && next->name != "WAIT"
 768                     && next->name != "END") {
 769                 prev = curr;
 770                 fp->IncrementWaypoint(false);
 771                 curr = fp->getCurrentWaypoint();
 772                 next = fp->getNextWaypoint();
 773             }
 774
 775         } else if (next->name == "WAITUNTIL") {
 776             double until_sec = processTimeString(next->time);
 777
 778             if (until_sec > _start_sec && start_sec < 0)
 779                 until_sec -= _day;
 780
 781             if (elapsed_sec < until_sec)
 782                 elapsed_sec = until_sec;
 783
 784             if (elapsed_sec >= day_sec )
 785                 break;
 786
 787             fp->IncrementWaypoint(false);
 788             next = fp->getNextWaypoint();
 789
 790             if (next->name != "WAITUNTIL" && next->name != "WAIT") {
 791                 prev = curr;
 792                 fp->IncrementWaypoint(false);
 793                 curr = fp->getCurrentWaypoint();
 794                 next = fp->getNextWaypoint();
 795             }
 796
 797             //cout << _name << ": end WAITUNTIL: ";
 798             //cout << prev->name << " " << curr->name << " " << next->name <<  endl;
 799
 800         } else {
 801             distance_nm = getRange(prev->latitude, prev->longitude, curr->latitude, curr->longitude);
 802             elapsed_sec += distance_nm * 60 * 60 / prev->speed;
 803
 804             if (elapsed_sec >= day_sec)
 805                 continue;
 806
 807             fp->IncrementWaypoint(false);
 808             prev = fp->getPreviousWaypoint();
 809             curr = fp->getCurrentWaypoint();
 810             next = fp->getNextWaypoint();
 811         }
 812
 813     }   // end while
 814
 815     // the required position lies between the previous and current waypoints
 816     // so we will calculate the distance back up the track from the current waypoint
 817     // then calculate the lat and lon.
 818     /*cout << "advancing flight plan done elapsed_sec: " << elapsed_sec
 819         << " " << day_sec << endl;*/
 820
 821     double time_diff = elapsed_sec - day_sec;
 822     double lat, lon, recip;
 823
 824     //cout << " time diff " << time_diff << endl;
 825
 826     if (next->name == "WAIT" ){
 827         setSpeed(0);
 828         lat = curr->latitude;
 829         lon = curr->longitude;
 830         _wait_count= time_diff;
 831         _waiting = true;
 832     } else if (next->name == "WAITUNTIL") {
 833         setSpeed(0);
 834         lat = curr->latitude;
 835         lon = curr->longitude;
 836         _waiting = true;
 837     } else {
 838         setSpeed(prev->speed);
 839         distance_nm = speed * time_diff / (60 * 60);
 840         double brg = getCourse(curr->latitude, curr->longitude, prev->latitude, prev->longitude);
 841
 842         //cout << " brg " << brg << " from " << curr->name << " to " << prev->name << " "
 843         //    << " lat "  << curr->latitude << " lon " << curr->longitude
 844         //    << " distance m " << distance_nm * SG_NM_TO_METER << endl;
 845
 846         lat = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 847             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 848         lon = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 849             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 850         recip = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 851             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 852     }
 853
 854     //cout << "Pos " << lat << ", " << lon << " recip " << recip << endl;
 855
 856     setLatitude(lat);
 857     setLongitude(lon);
 858     return true;
 859 }