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 #include <simgear/scene/util/SGNodeMasks.hxx>
  36
  37 #include "AIShip.hxx"
  38
  39
  40 FGAIShip::FGAIShip(object_type ot) :
  41     FGAIBase(ot),
  42     _dt_count(0),
  43     _next_run(0)
  44 {
  45 }
  46
  47 FGAIShip::~FGAIShip() {
  48 }
  49
  50 void FGAIShip::readFromScenario(SGPropertyNode* scFileNode) {
  51
  52     if (!scFileNode)
  53         return;
  54
  55     FGAIBase::readFromScenario(scFileNode);
  56
  57     setRudder(scFileNode->getFloatValue("rudder", 0.0));
  58     setName(scFileNode->getStringValue("name", "Titanic"));
  59     setRadius(scFileNode->getDoubleValue("turn-radius-ft", 2000));
  60     std::string flightplan = scFileNode->getStringValue("flightplan");
  61     setRepeat(scFileNode->getBoolValue("repeat", false));
  62     setStartTime(scFileNode->getStringValue("time", ""));
  63
  64     if (!flightplan.empty()) {
  65         FGAIFlightPlan* fp = new FGAIFlightPlan(flightplan);
  66         setFlightPlan(fp);
  67     }
  68
  69 }
  70
  71 bool FGAIShip::init(bool search_in_AI_path) {
  72     prev = 0; // the one behind you
  73     curr = 0; // the one ahead
  74     next = 0; // the next plus 1
  75
  76     _until_time = "";
  77
  78     props->setStringValue("name", _name.c_str());
  79     props->setStringValue("position/waypoint-name-prev", _prev_name.c_str());
  80     props->setStringValue("position/waypoint-name-curr", _curr_name.c_str());
  81     props->setStringValue("position/waypoint-name-next", _next_name.c_str());
  82     props->setStringValue("submodels/path", _path.c_str());
  83     props->setStringValue("position/waypoint-start-time", _start_time.c_str());
  84     props->setStringValue("position/waypoint-wait-until-time", _until_time.c_str());
  85
  86     _hdg_lock = false;
  87     _rudder = 0.0;
  88     no_roll = false;
  89
  90     _rudder_constant = 0.5;
  91     _roll_constant = 0.001;
  92     _speed_constant = 0.05;
  93     _hdg_constant = 0.01;
  94     _roll_factor = -0.0083335;
  95
  96     _rd_turn_radius_ft = _sp_turn_radius_ft = turn_radius_ft;
  97
  98     _fp_init = false;
  99     _missed = false;
 100     _waiting = false;
 101     _new_waypoint = true;
 102
 103     _missed_count = 0;
 104     _wait_count = 0;
 105     _missed_time_sec = 30;
 106
 107     _day = 86400;
 108
 109
 110     _wp_range = _old_range = 0;
 111     _range_rate = 0;
 112
 113     if (fp)
 114         _fp_init = initFlightPlan();
 115
 116     return FGAIBase::init(search_in_AI_path);
 117 }
 118
 119 void FGAIShip::initModel(osg::Node *node) {
 120     FGAIBase::initModel(node);
 121     model->setNodeMask(model->getNodeMask() | SG_NODEMASK_TERRAIN_BIT);
 122 }
 123
 124 void FGAIShip::bind() {
 125     FGAIBase::bind();
 126
 127     props->tie("surface-positions/rudder-pos-deg",
 128         SGRawValuePointer<float>(&_rudder));
 129     props->tie("controls/heading-lock",
 130         SGRawValuePointer<bool>(&_hdg_lock));
 131     props->tie("controls/tgt-speed-kts",
 132         SGRawValuePointer<double>(&tgt_speed));
 133     props->tie("controls/tgt-heading-degs",
 134         SGRawValuePointer<double>(&tgt_heading));
 135     props->tie("controls/constants/rudder",
 136         SGRawValuePointer<double>(&_rudder_constant));
 137     props->tie("controls/constants/roll-factor",
 138         SGRawValuePointer<double>(&_roll_factor));
 139     props->tie("controls/constants/roll",
 140         SGRawValuePointer<double>(&_roll_constant));
 141     props->tie("controls/constants/rudder",
 142         SGRawValuePointer<double>(&_rudder_constant));
 143     props->tie("controls/constants/speed",
 144         SGRawValuePointer<double>(&_speed_constant));
 145     props->tie("position/waypoint-range-nm",
 146         SGRawValuePointer<double>(&_wp_range));
 147     props->tie("position/waypoint-range-old-nm",
 148         SGRawValuePointer<double>(&_old_range));
 149     props->tie("position/waypoint-range-rate-nm-sec",
 150         SGRawValuePointer<double>(&_range_rate));
 151     props->tie("position/waypoint-new",
 152         SGRawValuePointer<bool>(&_new_waypoint));
 153     props->tie("position/waypoint-missed",
 154         SGRawValuePointer<bool>(&_missed));
 155     props->tie("position/waypoint-missed-count",
 156         SGRawValuePointer<double>(&_missed_count));
 157     props->tie("position/waypoint-missed-time-sec",
 158         SGRawValuePointer<double>(&_missed_time_sec));
 159     props->tie("position/waypoint-wait-count",
 160         SGRawValuePointer<double>(&_wait_count));
 161     props->tie("position/waypoint-waiting",
 162         SGRawValuePointer<bool>(&_waiting));
 163     props->tie("submodels/serviceable",
 164         SGRawValuePointer<bool>(&_serviceable));
 165 }
 166
 167 void FGAIShip::unbind() {
 168     FGAIBase::unbind();
 169     props->untie("surface-positions/rudder-pos-deg");
 170     props->untie("controls/heading-lock");
 171     props->untie("controls/tgt-speed-kts");
 172     props->untie("controls/tgt-heading-degs");
 173     props->untie("controls/constants/roll");
 174     props->untie("controls/constants/rudder");
 175     props->untie("controls/constants/roll-factor");
 176     props->untie("controls/constants/speed");
 177     props->untie("position/waypoint-range-nm");
 178     props->untie("position/waypoint-range-old-nm");
 179     props->untie("position/waypoint-range-rate-nm-sec");
 180     props->untie("position/waypoint-new");
 181     props->untie("position/waypoint-missed");
 182     props->untie("position/waypoint-missed-count");
 183     props->untie("position/waypoint-missed-time-sec");
 184     props->untie("position/waypoint-wait-count");
 185     props->untie("position/waypoint-waiting");
 186     props->untie("submodels/serviceable");
 187 }
 188
 189 void FGAIShip::update(double dt) {
 190     // For computation of rotation speeds we just use finite differences here.
 191     // That is perfectly valid since this thing is not driven by accelerations
 192     // but by just apply discrete changes at its velocity variables.
 193     // Update the velocity information stored in those nodes.
 194     // Transform that one to the horizontal local coordinate system.
 195     SGQuatd ec2hl = SGQuatd::fromLonLat(pos);
 196     // The orientation of the carrier wrt the horizontal local frame
 197     SGQuatd hl2body = SGQuatd::fromYawPitchRollDeg(hdg, pitch, roll);
 198     // and postrotate the orientation of the AIModel wrt the horizontal
 199     // local frame
 200     SGQuatd ec2body = ec2hl*hl2body;
 201     // The cartesian position of the carrier in the wgs84 world
 202     SGVec3d cartPos = SGVec3d::fromGeod(pos);
 203
 204     // The simulation time this transform is meant for
 205     aip.setReferenceTime(globals->get_sim_time_sec());
 206
 207     // Compute the velocity in m/s in the body frame
 208     aip.setBodyLinearVelocity(SGVec3d(0.51444444*speed, 0, 0));
 209
 210     FGAIBase::update(dt);
 211     Run(dt);
 212     Transform();
 213
 214     // Only change these values if we are able to compute them safely
 215     if (SGLimits<double>::min() < dt) {
 216         // Now here is the finite difference ...
 217
 218         // Transform that one to the horizontal local coordinate system.
 219         SGQuatd ec2hlNew = SGQuatd::fromLonLat(pos);
 220         // compute the new orientation
 221         SGQuatd hl2bodyNew = SGQuatd::fromYawPitchRollDeg(hdg, pitch, roll);
 222         // The rotation difference
 223         SGQuatd dOr = inverse(ec2body)*ec2hlNew*hl2bodyNew;
 224         SGVec3d dOrAngleAxis;
 225         dOr.getAngleAxis(dOrAngleAxis);
 226         // divided by the time difference provides a rotation speed vector
 227         dOrAngleAxis /= dt;
 228
 229         aip.setBodyAngularVelocity(dOrAngleAxis);
 230     }
 231 }
 232
 233 void FGAIShip::Run(double dt) {
 234     //cout << _name << " init: " << _fp_init << endl;
 235     if (_fp_init)
 236         ProcessFlightPlan(dt);
 237
 238     //    double speed_north_deg_sec;
 239     //    double speed_east_deg_sec;
 240     double alpha;
 241     double rudder_limit;
 242     double raw_roll;
 243
 244     // adjust speed
 245     double speed_diff = tgt_speed - speed;
 246
 247     if (fabs(speed_diff) > 0.1) {
 248
 249         if (speed_diff > 0.0)
 250             speed += _speed_constant * dt;
 251
 252         if (speed_diff < 0.0)
 253             speed -= _speed_constant * dt;
 254
 255     }
 256
 257     // do not allow unreasonable ship speeds
 258     if (speed > 40)
 259         speed = 40;
 260
 261     // convert speed to degrees per second
 262     speed_north_deg_sec = cos(hdg / SGD_RADIANS_TO_DEGREES)
 263         * speed * 1.686 / ft_per_deg_lat;
 264     speed_east_deg_sec = sin(hdg / SGD_RADIANS_TO_DEGREES)
 265         * speed * 1.686 / ft_per_deg_lon;
 266
 267     // set new position
 268     pos.setLatitudeDeg(pos.getLatitudeDeg() + speed_north_deg_sec * dt);
 269     pos.setLongitudeDeg(pos.getLongitudeDeg() + speed_east_deg_sec * dt);
 270
 271     // adjust heading based on current _rudder angle
 272
 273     //cout << "turn_radius_ft " << turn_radius_ft ;
 274
 275     if (turn_radius_ft <= 0)
 276         turn_radius_ft = 0; // don't allow nonsense values
 277
 278     if (_rudder > 45)
 279         _rudder = 45;
 280
 281     if (_rudder < -45)
 282         _rudder = -45;
 283
 284     //we assume that at slow speed ships will manoeuvre using engines/bow thruster
 285     if (fabs(speed)<=5)
 286         _sp_turn_radius_ft = 500;
 287     else
 288         // adjust turn radius for speed. The equation is very approximate.
 289         // we need to allow for negative speeds
 290         _sp_turn_radius_ft = 10 * pow ((fabs(speed) - 15), 2) + turn_radius_ft;
 291
 292     //cout << " speed turn radius " << _sp_turn_radius_ft ;
 293
 294     if (_rudder <= -0.25 || _rudder >= 0.25) {
 295         // adjust turn radius for _rudder angle. The equation is even more approximate.
 296         float a = 19;
 297         float b = -0.2485;
 298         float c = 0.543;
 299
 300         _rd_turn_radius_ft = (a * exp(b * fabs(_rudder)) + c) * _sp_turn_radius_ft;
 301
 302         //cout <<" _rudder turn radius " << _rd_turn_radius_ft << endl;
 303
 304         // calculate the angle, alpha, subtended by the arc traversed in time dt
 305         alpha = ((speed * 1.686 * dt) / _rd_turn_radius_ft) * SG_RADIANS_TO_DEGREES;
 306
 307         // make sure that alpha is applied in the right direction
 308         hdg += alpha * sign(_rudder);
 309
 310         if (hdg > 360.0)
 311             hdg -= 360.0;
 312
 313         if (hdg < 0.0)
 314             hdg += 360.0;
 315
 316         //adjust roll for rudder angle and speed. Another bit of voodoo
 317         raw_roll = _roll_factor * speed * _rudder;
 318     } else {
 319         // _rudder angle is 0
 320         raw_roll = 0;
 321     }
 322
 323     //low pass filter
 324     if (speed < 0)
 325         roll = -roll;
 326
 327     roll = (raw_roll * _roll_constant) + (roll * (1 - _roll_constant));
 328
 329     // adjust target _rudder angle if heading lock engaged
 330     double rudder_diff = 0.0;
 331     if (_hdg_lock) {
 332         double rudder_sense = 0.0;
 333         double diff = fabs(hdg - tgt_heading);
 334         //cout << "_rudder diff" << diff << endl;
 335         if (diff > 180)
 336             diff = fabs(diff - 360);
 337
 338         double sum = hdg + diff;
 339
 340         if (sum > 360.0)
 341             sum -= 360.0;
 342
 343         if (fabs(sum - tgt_heading)< 1.0)
 344             rudder_sense = 1.0;
 345         else
 346             rudder_sense = -1.0;
 347
 348         if (speed < 0)
 349             rudder_sense = -rudder_sense;
 350
 351         if (diff < 15)
 352             _tgt_rudder = diff * rudder_sense;
 353         else
 354             _tgt_rudder = 45 * rudder_sense;
 355
 356         rudder_diff = _tgt_rudder - _rudder;
 357     }
 358
 359     // set the _rudder limit by speed
 360     if (speed <= 40)
 361         rudder_limit = (-0.825 * speed) + 35;
 362     else
 363         rudder_limit = 2;
 364
 365     if (fabs(rudder_diff)> 0.1) { // apply dead zone
 366
 367         if (rudder_diff > 0.0) {
 368             _rudder += _rudder_constant * dt;
 369
 370             if (_rudder > rudder_limit) // apply the _rudder limit
 371                 _rudder = rudder_limit;
 372
 373         } else if (rudder_diff < 0.0) {
 374             _rudder -= _rudder_constant * dt;
 375
 376             if (_rudder < -rudder_limit)
 377                 _rudder = -rudder_limit;
 378
 379         }
 380
 381         // do calculations for radar
 382         UpdateRadar(manager);
 383     }
 384 }//end function
 385
 386 void FGAIShip::AccelTo(double speed) {
 387     tgt_speed = speed;
 388 }
 389
 390 void FGAIShip::PitchTo(double angle) {
 391     tgt_pitch = angle;
 392 }
 393
 394 void FGAIShip::RollTo(double angle) {
 395     tgt_roll = angle;
 396 }
 397
 398 void FGAIShip::YawTo(double angle) {
 399 }
 400
 401 void FGAIShip::ClimbTo(double altitude) {
 402 }
 403
 404
 405 void FGAIShip::TurnTo(double heading) {
 406     tgt_heading = heading;
 407     _hdg_lock = true;
 408 }
 409
 410 double FGAIShip::sign(double x) {
 411     if (x < 0.0)
 412         return -1.0;
 413     else
 414         return 1.0;
 415 }
 416
 417 void FGAIShip::setFlightPlan(FGAIFlightPlan* f) {
 418     fp = f;
 419 }
 420
 421 void FGAIShip::setName(const string& n) {
 422     _name = n;
 423 }
 424
 425 void FGAIShip::setStartTime(const string& st) {
 426     _start_time = st;
 427 }
 428
 429 void FGAIShip::setUntilTime(const string& ut) {
 430     _until_time = ut;
 431     props->setStringValue("position/waypoint-wait-until-time", _until_time.c_str());
 432 }
 433
 434 void FGAIShip::setCurrName(const string& c) {
 435     _curr_name = c;
 436     props->setStringValue("position/waypoint-name-curr", _curr_name.c_str());
 437 }
 438
 439 void FGAIShip::setNextName(const string& n) {
 440     _next_name = n;
 441     props->setStringValue("position/waypoint-name-next", _next_name.c_str());
 442 }
 443
 444 void FGAIShip::setPrevName(const string& p) {
 445     _prev_name = p;
 446     props->setStringValue("position/waypoint-name-prev", _prev_name.c_str());
 447 }
 448
 449 void FGAIShip::setRepeat(bool r) {
 450     _repeat = r;
 451 }
 452
 453 void FGAIShip::setMissed(bool m) {
 454     _missed = m;
 455     props->setBoolValue("position/waypoint-missed", _missed);
 456 }
 457
 458 void FGAIShip::setRudder(float r) {
 459     _rudder = r;
 460 }
 461
 462 void FGAIShip::setRoll(double rl) {
 463     roll = rl;
 464 }
 465
 466 void FGAIShip::setWPNames() {
 467
 468     if (prev != 0)
 469         setPrevName(prev->name);
 470     else
 471         setPrevName("");
 472
 473     setCurrName(curr->name);
 474
 475     if (next != 0)
 476         setNextName(next->name);
 477     else
 478         setNextName("");
 479
 480     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: prev wp name " << prev->name);
 481     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: current wp name " << curr->name);
 482     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: next wp name " << next->name);
 483
 484 }
 485
 486 double FGAIShip::getRange(double lat, double lon, double lat2, double lon2) const {
 487
 488     double course, distance, az2;
 489
 490     //calculate the bearing and range of the second pos from the first
 491     geo_inverse_wgs_84(lat, lon, lat2, lon2, &course, &az2, &distance);
 492     distance *= SG_METER_TO_NM;
 493     return distance;
 494 }
 495
 496 double FGAIShip::getCourse(double lat, double lon, double lat2, double lon2) const {
 497
 498     double course, distance, recip;
 499
 500     //calculate the bearing and range of the second pos from the first
 501     geo_inverse_wgs_84(lat, lon, lat2, lon2, &course, &recip, &distance);
 502     if (tgt_speed >= 0) {
 503         return course;
 504     } else {
 505         return recip;
 506     }
 507 }
 508
 509 void FGAIShip::ProcessFlightPlan(double dt) {
 510
 511     double time_sec = getDaySeconds();
 512     double until_time_sec = 0;
 513
 514     _missed = false;
 515     _dt_count += dt;
 516
 517     ///////////////////////////////////////////////////////////////////////////
 518     // Check Execution time (currently once every 1 sec)
 519     // Add a bit of randomization to prevent the execution of all flight plans
 520     // in synchrony, which can add significant periodic framerate flutter.
 521     ///////////////////////////////////////////////////////////////////////////
 522
 523     //cout << "_start_sec " << _start_sec << " time_sec " << time_sec << endl;
 524     if (_dt_count < _next_run && _start_sec < time_sec)
 525         return;
 526
 527     _next_run = 1.0 + (0.5 * sg_random());
 528
 529     // check to see if we've reached the point for our next turn
 530     // if the range to the waypoint is less than the calculated turn
 531     // radius we can start the turn to the next leg
 532     _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 533     _range_rate = (_wp_range - _old_range) / _dt_count;
 534     double sp_turn_radius_nm = _sp_turn_radius_ft / 6076.1155;
 535
 536     // we need to try to identify a _missed waypoint
 537
 538     // calculate the time needed to turn through an arc of 90 degrees, and allow an error of 30 secs
 539     if (speed != 0)
 540         _missed_time_sec = 30 + ((SGD_PI * sp_turn_radius_nm * 60 * 60) / (2 * fabs(speed)));
 541     else
 542         _missed_time_sec = 30;
 543
 544     if ((_range_rate > 0) && (_wp_range < 3 * sp_turn_radius_nm) && !_new_waypoint)
 545         _missed_count += _dt_count;
 546
 547     if (_missed_count >= _missed_time_sec) {
 548         setMissed(true);
 549     } else {
 550         setMissed(false);
 551     }
 552
 553     _old_range = _wp_range;
 554     setWPNames();
 555
 556     if ((_wp_range < sp_turn_radius_nm) || _missed || _waiting && !_new_waypoint) {
 557
 558         if (_next_name == "END") {
 559
 560             if (_repeat) {
 561                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Flightplan restarting ");
 562                 fp->restart();
 563                 prev = curr;
 564                 curr = fp->getCurrentWaypoint();
 565                 next = fp->getNextWaypoint();
 566                 setWPNames();
 567                 _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 568                 _old_range = _wp_range;
 569                 _range_rate = 0;
 570                 _new_waypoint = true;
 571                 _missed_count = 0;
 572                 AccelTo(prev->speed);
 573             } else {
 574                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Flightplan dieing ");
 575                 setDie(true);
 576                 _dt_count = 0;
 577                 return;
 578             }
 579
 580         } else if (_next_name == "WAIT") {
 581
 582             if (_wait_count < next->time_sec) {
 583                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " waiting ");
 584                 setSpeed(0);
 585                 _waiting = true;
 586                 _wait_count += _dt_count;
 587                 _dt_count = 0;
 588                 return;
 589             } else {
 590                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name
 591                     << " wait done: getting new waypoints ");
 592                 _waiting = false;
 593                 _wait_count = 0;
 594                 fp->IncrementWaypoint(false);
 595                 next = fp->getNextWaypoint();
 596
 597                 if (next->name == "WAITUNTIL" || next->name == "WAIT"
 598                         || next->name == "END")
 599                     return;
 600
 601                 prev = curr;
 602                 fp->IncrementWaypoint(false);
 603                 curr = fp->getCurrentWaypoint();
 604                 next = fp->getNextWaypoint();
 605             }
 606
 607         } else if (_next_name == "WAITUNTIL") {
 608             time_sec = getDaySeconds();
 609             until_time_sec = processTimeString(next->time);
 610             _until_time = next->time;
 611             setUntilTime(next->time);
 612             if (until_time_sec > time_sec) {
 613                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " waiting until: "
 614                     << _until_time << " " << until_time_sec << " now " << time_sec );
 615                 setSpeed(0);
 616                 _waiting = true;
 617                 return;
 618             } else {
 619                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: "
 620                     << _name << " wait until done: getting new waypoints ");
 621                 setUntilTime("");
 622                 fp->IncrementWaypoint(false);
 623
 624                 while (next->name == "WAITUNTIL") {
 625                     fp->IncrementWaypoint(false);
 626                     next = fp->getNextWaypoint();
 627                 }
 628
 629                 if (next->name == "WAIT")
 630                     return;
 631
 632                 prev = curr;
 633                 fp->IncrementWaypoint(false);
 634                 curr = fp->getCurrentWaypoint();
 635                 next = fp->getNextWaypoint();
 636                 _waiting = false;
 637             }
 638
 639         } else {
 640             //now reorganise the waypoints, so that next becomes current and so on
 641             SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " getting new waypoints ");
 642             fp->IncrementWaypoint(false);
 643             prev = fp->getPreviousWaypoint(); //first waypoint
 644             curr = fp->getCurrentWaypoint();  //second waypoint
 645             next = fp->getNextWaypoint();     //third waypoint (might not exist!)
 646         }
 647
 648         setWPNames();
 649         _new_waypoint = true;
 650         _missed_count = 0;
 651         _range_rate = 0;
 652         _wp_range = getRange(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 653         _old_range = _wp_range;
 654         AccelTo(prev->speed);
 655     } else {
 656         _new_waypoint = false;
 657     }
 658
 659     //   now revise the required course for the next way point
 660     double course = getCourse(pos.getLatitudeDeg(), pos.getLongitudeDeg(), curr->latitude, curr->longitude);
 661
 662     if (finite(course))
 663         TurnTo(course);
 664     else
 665         SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: Bearing or Range is not a finite number");
 666
 667      _dt_count = 0;
 668 } // end Processing FlightPlan
 669
 670 bool FGAIShip::initFlightPlan() {
 671
 672     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " initializing waypoints ");
 673
 674     bool init = false;
 675
 676     _start_sec = 0;
 677
 678     fp->restart();
 679     fp->IncrementWaypoint(false);
 680
 681     prev = fp->getPreviousWaypoint(); //first waypoint
 682     curr = fp->getCurrentWaypoint();  //second waypoint
 683     next = fp->getNextWaypoint();     //third waypoint (might not exist!)
 684
 685     while (curr->name == "WAIT" || curr->name == "WAITUNTIL") {  // don't wait when initialising
 686         SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " re-initializing waypoints ");
 687         fp->IncrementWaypoint(false);
 688         curr = fp->getCurrentWaypoint();
 689         next = fp->getNextWaypoint();
 690     }
 691
 692     if (!_start_time.empty()){
 693         _start_sec = processTimeString(_start_time);
 694         double day_sec = getDaySeconds();
 695
 696         if (_start_sec < day_sec){
 697             //cout << "flight plan has already started " << _start_time << endl;
 698             init = advanceFlightPlan(_start_sec, day_sec);
 699
 700         } else if (_start_sec > day_sec && _repeat) {
 701             //cout << "flight plan has not started, " << _start_time;
 702             //cout << "offsetting start time by -24 hrs" << endl;
 703             _start_sec -= _day;
 704             init = advanceFlightPlan(_start_sec, day_sec);
 705         }
 706
 707         if (init)
 708             _start_sec = 0; // set to zero for an immediate start of the Flight Plan
 709         else {
 710             fp->restart();
 711             fp->IncrementWaypoint(false);
 712             prev = fp->getPreviousWaypoint();
 713             curr = fp->getCurrentWaypoint();
 714             next = fp->getNextWaypoint();
 715             return false;
 716         }
 717
 718     } else {
 719     setLatitude(prev->latitude);
 720     setLongitude(prev->longitude);
 721     setSpeed(prev->speed);
 722     }
 723
 724     setWPNames();
 725     setHeading(getCourse(prev->latitude, prev->longitude, curr->latitude, curr->longitude));
 726     _wp_range = getRange(prev->latitude, prev->longitude, curr->latitude, curr->longitude);
 727     _old_range = _wp_range;
 728     _range_rate = 0;
 729     _hdg_lock = true;
 730     _missed = false;
 731     _missed_count = 0;
 732     _new_waypoint = true;
 733
 734     SG_LOG(SG_GENERAL, SG_DEBUG, "AIShip: " << _name << " done initialising waypoints ");
 735     if (prev)
 736         init = true;
 737
 738     if (init)
 739         return true;
 740     else
 741         return false;
 742
 743 } // end of initialization
 744
 745
 746 double FGAIShip::processTimeString(const string& theTime) {
 747
 748     int Hour;
 749     int Minute;
 750     int Second;
 751
 752     // first split theTime string into
 753     //  hour, minute, second and convert to int;
 754     Hour   = atoi(theTime.substr(0,2).c_str());
 755     Minute = atoi(theTime.substr(3,5).c_str());
 756     Second = atoi(theTime.substr(6,8).c_str());
 757
 758     // offset by a day-sec to allow for starting a day earlier
 759     double time_seconds = Hour * 3600
 760         + Minute * 60
 761         + Second;
 762
 763     return time_seconds;
 764 }
 765
 766 double FGAIShip::getDaySeconds () {
 767     // Date and time
 768     struct tm *t = globals->get_time_params()->getGmt();
 769
 770     double day_seconds = t->tm_hour * 3600
 771         + t->tm_min * 60
 772         + t->tm_sec;
 773
 774     return day_seconds;
 775 }
 776
 777 bool FGAIShip::advanceFlightPlan (double start_sec, double day_sec) {
 778
 779     double elapsed_sec = start_sec;
 780     double distance_nm = 0;
 781
 782     //cout << "advancing flight plan start_sec: " << start_sec << " " << day_sec << endl;
 783
 784     while ( elapsed_sec < day_sec ) {
 785
 786         if (next->name == "END") {
 787
 788             if (_repeat ) {
 789                 //cout << _name << ": " << "restarting flightplan" << endl;
 790                 fp->restart();
 791                 curr = fp->getCurrentWaypoint();
 792                 next = fp->getNextWaypoint();
 793             } else {
 794                 //cout << _name << ": " << "ending flightplan" << endl;
 795                 setDie(true);
 796                 return false;
 797             }
 798
 799         } else if (next->name == "WAIT") {
 800             //cout << _name << ": begin WAIT: " << prev->name << " ";
 801             //cout << curr->name << " " << next->name << endl;
 802
 803             elapsed_sec += next->time_sec;
 804
 805             if ( elapsed_sec >= day_sec)
 806                 continue;
 807
 808             fp->IncrementWaypoint(false);
 809             next = fp->getNextWaypoint();
 810
 811             if (next->name != "WAITUNTIL" && next->name != "WAIT"
 812                     && next->name != "END") {
 813                 prev = curr;
 814                 fp->IncrementWaypoint(false);
 815                 curr = fp->getCurrentWaypoint();
 816                 next = fp->getNextWaypoint();
 817             }
 818
 819         } else if (next->name == "WAITUNTIL") {
 820             double until_sec = processTimeString(next->time);
 821
 822             if (until_sec > _start_sec && start_sec < 0)
 823                 until_sec -= _day;
 824
 825             if (elapsed_sec < until_sec)
 826                 elapsed_sec = until_sec;
 827
 828             if (elapsed_sec >= day_sec )
 829                 break;
 830
 831             fp->IncrementWaypoint(false);
 832             next = fp->getNextWaypoint();
 833
 834             if (next->name != "WAITUNTIL" && next->name != "WAIT") {
 835                 prev = curr;
 836                 fp->IncrementWaypoint(false);
 837                 curr = fp->getCurrentWaypoint();
 838                 next = fp->getNextWaypoint();
 839             }
 840
 841             //cout << _name << ": end WAITUNTIL: ";
 842             //cout << prev->name << " " << curr->name << " " << next->name <<  endl;
 843
 844         } else {
 845             distance_nm = getRange(prev->latitude, prev->longitude, curr->latitude, curr->longitude);
 846             elapsed_sec += distance_nm * 60 * 60 / prev->speed;
 847
 848             if (elapsed_sec >= day_sec)
 849                 continue;
 850
 851             fp->IncrementWaypoint(false);
 852             prev = fp->getPreviousWaypoint();
 853             curr = fp->getCurrentWaypoint();
 854             next = fp->getNextWaypoint();
 855         }
 856
 857     }   // end while
 858
 859     // the required position lies between the previous and current waypoints
 860     // so we will calculate the distance back up the track from the current waypoint
 861     // then calculate the lat and lon.
 862     /*cout << "advancing flight plan done elapsed_sec: " << elapsed_sec
 863         << " " << day_sec << endl;*/
 864
 865     double time_diff = elapsed_sec - day_sec;
 866     double lat, lon, recip;
 867
 868     //cout << " time diff " << time_diff << endl;
 869
 870     if (next->name == "WAIT" ){
 871         setSpeed(0);
 872         lat = curr->latitude;
 873         lon = curr->longitude;
 874         _wait_count= time_diff;
 875         _waiting = true;
 876     } else if (next->name == "WAITUNTIL") {
 877         setSpeed(0);
 878         lat = curr->latitude;
 879         lon = curr->longitude;
 880         _waiting = true;
 881     } else {
 882         setSpeed(prev->speed);
 883         distance_nm = speed * time_diff / (60 * 60);
 884         double brg = getCourse(curr->latitude, curr->longitude, prev->latitude, prev->longitude);
 885
 886         //cout << " brg " << brg << " from " << curr->name << " to " << prev->name << " "
 887         //    << " lat "  << curr->latitude << " lon " << curr->longitude
 888         //    << " distance m " << distance_nm * SG_NM_TO_METER << endl;
 889
 890         lat = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 891             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 892         lon = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 893             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 894         recip = geo_direct_wgs_84 (curr->latitude, curr->longitude, brg,
 895             distance_nm * SG_NM_TO_METER, &lat, &lon, &recip );
 896     }
 897
 898     //cout << "Pos " << lat << ", " << lon << " recip " << recip << endl;
 899
 900     setLatitude(lat);
 901     setLongitude(lon);
 902     return true;
 903 }