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