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