src/AIModel/AIBallistic.cxx

   1 // FGAIBallistic - FGAIBase-derived class creates a ballistic object
   2 //
   3 // Written by David Culp, started November 2003.
   4 // - davidculp2@comcast.net
   5 //
   6 // With major additions by Mathias Froehlich & Vivian Meazza 2004-2008
   7 //
   8 // This program is free software; you can redistribute it and/or
   9 // modify it under the terms of the GNU General Public License as
  10 // published by the Free Software Foundation; either version 2 of the
  11 // License, or (at your option) any later version.
  12 //
  13 // This program is distributed in the hope that it will be useful, but
  14 // WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 // General Public License for more details.
  17 //
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  21
  22 #ifdef HAVE_CONFIG_H
  23 #  include <config.h>
  24 #endif
  25
  26 #include <simgear/math/sg_random.h>
  27 #include <simgear/math/sg_geodesy.hxx>
  28 #include <simgear/scene/model/modellib.hxx>
  29
  30 #include <Scenery/scenery.hxx>
  31
  32 #include "AIBallistic.hxx"
  33
  34 #include <Main/util.hxx>
  35
  36 using namespace simgear;
  37
  38 const double FGAIBallistic::slugs_to_kgs = 14.5939029372;
  39 const double FGAIBallistic::slugs_to_lbs = 32.1740485564;
  40
  41 FGAIBallistic::FGAIBallistic(object_type ot) :
  42     FGAIBase(ot),
  43     _height(0.0),
  44     _ht_agl_ft(0.0),
  45     _azimuth(0.0),
  46     _elevation(0.0),
  47     _rotation(0.0),
  48     _formate_to_ac(false),
  49     _aero_stabilised(false),
  50     _drag_area(0.007),
  51     _life_timer(0.0),
  52     _gravity(32.1740485564),
  53     _buoyancy(0),
  54     _wind(true),
  55     _mass(0),
  56     _random(false),
  57     _load_resistance(0),
  58     _solid(false),
  59     _force_stabilised(false),
  60     _slave_to_ac(false),
  61     _slave_load_to_ac(false),
  62     _contents_lb(0),
  63     _report_collision(false),
  64         _report_expiry(false),
  65     _report_impact(false),
  66     _external_force(false),
  67     _impact_report_node(fgGetNode("/ai/models/model-impact", true)),
  68     _old_height(0),
  69         _elapsed_time(0)
  70
  71 {
  72     no_roll = false;
  73 }
  74
  75 FGAIBallistic::~FGAIBallistic() {
  76 }
  77
  78 void FGAIBallistic::readFromScenario(SGPropertyNode* scFileNode) {
  79     if (!scFileNode){
  80         return;
  81     }
  82
  83     FGAIBase::readFromScenario(scFileNode);
  84
  85     //setPath(scFileNode->getStringValue("model", "Models/Geometry/rocket.ac"));
  86         setRandom(scFileNode->getBoolValue("random", false));
  87     setAzimuth(scFileNode->getDoubleValue("azimuth", 0.0));
  88     setElevation(scFileNode->getDoubleValue("elevation", 0));
  89     setDragArea(scFileNode->getDoubleValue("eda", 0.007));
  90     setLife(scFileNode->getDoubleValue("life", 900.0));
  91     setBuoyancy(scFileNode->getDoubleValue("buoyancy", 0));
  92     setWind_from_east(scFileNode->getDoubleValue("wind_from_east", 0));
  93     setWind_from_north(scFileNode->getDoubleValue("wind_from_north", 0));
  94     setWind(scFileNode->getBoolValue("wind", false));
  95     setRoll(scFileNode->getDoubleValue("roll", 0.0));
  96     setCd(scFileNode->getDoubleValue("cd", 0.029));
  97     //setMass(scFileNode->getDoubleValue("mass", 0.007));
  98     setWeight(scFileNode->getDoubleValue("weight", 0.25));
  99     setStabilisation(scFileNode->getBoolValue("aero-stabilised", false));
 100     setNoRoll(scFileNode->getBoolValue("no-roll", false));
 101     setImpact(scFileNode->getBoolValue("impact", false));
 102         setExpiry(scFileNode->getBoolValue("expiry", false));
 103         setCollision(scFileNode->getBoolValue("collision", false));
 104     setImpactReportNode(scFileNode->getStringValue("impact-reports"));
 105     setName(scFileNode->getStringValue("name", "Rocket"));
 106     setFuseRange(scFileNode->getDoubleValue("fuse-range", 0.0));
 107     setSMPath(scFileNode->getStringValue("submodel-path", ""));
 108     setSubID(scFileNode->getIntValue("SubID", 0));
 109     setExternalForce(scFileNode->getBoolValue("external-force", false));
 110     setForcePath(scFileNode->getStringValue("force-path", ""));
 111     setForceStabilisation(scFileNode->getBoolValue("force-stabilised", false));
 112     setXoffset(scFileNode->getDoubleValue("x-offset", 0.0));
 113     setYoffset(scFileNode->getDoubleValue("y-offset", 0.0));
 114     setZoffset(scFileNode->getDoubleValue("z-offset", 0.0));
 115     setPitchoffset(scFileNode->getDoubleValue("pitch-offset", 0.0));
 116     setRolloffset(scFileNode->getDoubleValue("roll-offset", 0.0));
 117     setYawoffset(scFileNode->getDoubleValue("yaw-offset", 0.0));
 118     setGroundOffset(scFileNode->getDoubleValue("ground-offset", 0.0));
 119     setLoadOffset(scFileNode->getDoubleValue("load-offset", 0.0));
 120     setSlaved(scFileNode->getBoolValue("slaved", false));
 121     setSlavedLoad(scFileNode->getBoolValue("slaved-load", false));
 122     setContentsNode(scFileNode->getStringValue("contents"));
 123 }
 124
 125 bool FGAIBallistic::init(bool search_in_AI_path) {
 126     FGAIBase::init(search_in_AI_path);
 127
 128     _impact_reported = false;
 129     _collision_reported = false;
 130         _expiry_reported = false;
 131
 132         _impact_lat = 0;
 133     _impact_lon = 0;
 134     _impact_elev = 0;
 135     _impact_hdg = 0;
 136     _impact_pitch = 0;
 137     _impact_roll = 0;
 138     _impact_speed = 0;
 139
 140     invisible = false;
 141
 142     _elapsed_time += (sg_random() * 100);
 143
 144     props->setStringValue("material/name", "");
 145     props->setStringValue("name", _name.c_str());
 146     props->setStringValue("submodels/path", _submodel.c_str());
 147         props->setStringValue("force/path", _force_path.c_str());
 148         //props->setStringValue("vector/path", _vector_path.c_str());
 149
 150     // start with high value so that animations don't trigger yet
 151     _ht_agl_ft = 1e10;
 152     hdg = _azimuth;
 153     pitch = _elevation;
 154     roll = _rotation;
 155
 156     Transform();
 157
 158     return true;
 159 }
 160
 161 void FGAIBallistic::bind() {
 162     //    FGAIBase::bind();
 163
 164     props->tie("sim/time/elapsed-sec",
 165         SGRawValueMethods<FGAIBallistic,double>(*this,
 166         &FGAIBallistic::_getTime));
 167     props->tie("mass-slug",
 168         SGRawValueMethods<FGAIBallistic,double>(*this,
 169         &FGAIBallistic::getMass));
 170     props->tie("material/load-resistance",
 171                 SGRawValuePointer<double>(&_load_resistance));
 172     props->tie("material/solid",
 173                 SGRawValuePointer<bool>(&_solid));
 174     props->tie("altitude-agl-ft",
 175                 SGRawValuePointer<double>(&_ht_agl_ft));
 176     props->tie("controls/slave-to-ac",
 177         SGRawValueMethods<FGAIBallistic,bool>
 178         (*this, &FGAIBallistic::getSlaved, &FGAIBallistic::setSlaved));
 179     props->tie("controls/invisible",
 180         SGRawValuePointer<bool>(&invisible));
 181
 182     if(_external_force){
 183         props->tie("controls/force_stabilized",
 184             SGRawValuePointer<bool>(&_force_stabilised));
 185         props->tie("position/global-x",
 186             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosX, 0));
 187         props->tie("position/global-y",
 188             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosY, 0));
 189         props->tie("position/global-z",
 190             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosZ, 0));
 191         props->tie("velocities/vertical-speed-fps",
 192             SGRawValuePointer<double>(&vs));
 193         props->tie("velocities/true-airspeed-kt",
 194             SGRawValuePointer<double>(&speed));
 195         props->tie("velocities/horizontal-speed-fps",
 196             SGRawValuePointer<double>(&hs));
 197         props->tie("position/altitude-ft",
 198             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getAltitude, &FGAIBase::_setAltitude));
 199         props->tie("position/latitude-deg",
 200             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLatitude, &FGAIBase::_setLatitude));
 201         props->tie("position/longitude-deg",
 202             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLongitude, &FGAIBase::_setLongitude));
 203         props->tie("orientation/hdg-deg",
 204             SGRawValuePointer<double>(&hdg));
 205         props->tie("orientation/pitch-deg",
 206             SGRawValuePointer<double>(&pitch));
 207         props->tie("orientation/roll-deg",
 208             SGRawValuePointer<double>(&roll));
 209         props->tie("controls/slave-load-to-ac",
 210             SGRawValueMethods<FGAIBallistic,bool>
 211             (*this, &FGAIBallistic::getSlavedLoad, &FGAIBallistic::setSlavedLoad));
 212         props->tie("position/load-offset",
 213             SGRawValueMethods<FGAIBallistic,double>
 214             (*this, &FGAIBallistic::getLoadOffset, &FGAIBallistic::setLoadOffset));
 215         props->tie("load/distance-to-hitch-ft",
 216             SGRawValueMethods<FGAIBallistic,double>
 217             (*this, &FGAIBallistic::getDistanceLoadToHitch));
 218         props->tie("load/elevation-to-hitch-deg",
 219             SGRawValueMethods<FGAIBallistic,double>
 220             (*this, &FGAIBallistic::getElevLoadToHitch));
 221         props->tie("load/bearing-to-hitch-deg",
 222             SGRawValueMethods<FGAIBallistic,double>
 223             (*this, &FGAIBallistic::getBearingLoadToHitch));
 224     }
 225
 226 }
 227
 228 void FGAIBallistic::unbind() {
 229     //    FGAIBase::unbind();
 230
 231     props->untie("sim/time/elapsed-sec");
 232     props->untie("mass-slug");
 233     props->untie("material/load-resistance");
 234     props->untie("material/solid");
 235     props->untie("altitude-agl-ft");
 236     props->untie("controls/slave-to-ac");
 237     props->untie("controls/invisible");
 238
 239     if(_external_force){
 240         props->untie("position/global-y");
 241         props->untie("position/global-x");
 242         props->untie("position/global-z");
 243         props->untie("velocities/vertical-speed-fps");
 244         props->untie("velocities/true-airspeed-kt");
 245         props->untie("velocities/horizontal-speed-fps");
 246         props->untie("position/altitude-ft");
 247         props->untie("position/latitude-deg");
 248         props->untie("position/longitude-deg");
 249         props->untie("position/ht-agl-ft");
 250         props->untie("orientation/hdg-deg");
 251         props->untie("orientation/pitch-deg");
 252         props->untie("orientation/roll-deg");
 253         props->untie("controls/force_stabilized");
 254         props->untie("position/load-offset");
 255         props->untie("load/distance-to-hitch-ft");
 256         props->untie("load/elevation-to-hitch-deg");
 257         props->untie("load/bearing-to-hitch-deg");
 258     }
 259 }
 260
 261 void FGAIBallistic::update(double dt) {
 262     FGAIBase::update(dt);
 263     _setUserPos();
 264
 265     if (_slave_to_ac){
 266         slaveToAC(dt);
 267         Transform();
 268         setHitchVelocity(dt);
 269     } else if (_formate_to_ac){
 270         formateToAC(dt);
 271         Transform();
 272         setHitchVelocity(dt);
 273     } else if (!invisible){
 274     Run(dt);
 275     Transform();
 276 }
 277
 278 }
 279
 280 void FGAIBallistic::setAzimuth(double az) {
 281
 282         if (_random)
 283                 hdg = _azimuth = (az - 5 ) + (10 * sg_random());
 284         else
 285                 hdg = _azimuth = az;
 286
 287         //cout << _name << " init hdg " << hdg << " random " << _random << endl;
 288 }
 289
 290 void FGAIBallistic::setElevation(double el) {
 291     pitch = _elevation = el;
 292 }
 293
 294 void FGAIBallistic::setRoll(double rl) {
 295     roll = _rotation = rl;
 296 }
 297
 298 void FGAIBallistic::setStabilisation(bool val) {
 299     _aero_stabilised = val;
 300 }
 301
 302 void FGAIBallistic::setForceStabilisation(bool val) {
 303     _force_stabilised = val;
 304 }
 305
 306 void FGAIBallistic::setNoRoll(bool nr) {
 307     no_roll = nr;
 308 }
 309
 310 void FGAIBallistic::setDragArea(double a) {
 311     _drag_area = a;
 312 }
 313
 314 void FGAIBallistic::setLife(double seconds) {
 315
 316         if (_random){
 317                 life = seconds * _randomness + (seconds * (1 -_randomness) * sg_random());
 318                 //cout << "life " << life << endl;
 319         } else
 320                 life = seconds;
 321 }
 322
 323 void FGAIBallistic::setBuoyancy(double fpss) {
 324     _buoyancy = fpss;
 325 }
 326
 327 void FGAIBallistic::setWind_from_east(double fps) {
 328     _wind_from_east = fps;
 329 }
 330
 331 void FGAIBallistic::setWind_from_north(double fps) {
 332     _wind_from_north = fps;
 333 }
 334
 335 void FGAIBallistic::setWind(bool val) {
 336     _wind = val;
 337 }
 338
 339 void FGAIBallistic::setCd(double c) {
 340     _Cd = c;
 341 }
 342
 343 void FGAIBallistic::setMass(double m) {
 344     _mass = m;
 345 }
 346
 347 void FGAIBallistic::setWeight(double w) {
 348     _weight_lb = w;
 349 }
 350
 351 void FGAIBallistic::setRandomness(double r) {
 352     _randomness = r;
 353 }
 354
 355 void FGAIBallistic::setRandom(bool r) {
 356     _random = r;
 357 }
 358
 359 void FGAIBallistic::setImpact(bool i) {
 360     _report_impact = i;
 361 }
 362
 363 void FGAIBallistic::setCollision(bool c) {
 364     _report_collision = c;
 365 }
 366
 367 void FGAIBallistic::setExpiry(bool e) {
 368     _report_expiry = e;
 369         //cout <<  "_report_expiry " << _report_expiry << endl;
 370 }
 371
 372 void FGAIBallistic::setExternalForce(bool f) {
 373     _external_force = f;
 374 }
 375
 376 void FGAIBallistic::setImpactReportNode(const string& path) {
 377
 378     if (!path.empty())
 379         _impact_report_node = fgGetNode(path.c_str(), true);
 380 }
 381
 382 void FGAIBallistic::setName(const string& n) {
 383     _name = n;
 384 }
 385
 386 void FGAIBallistic::setSMPath(const string& s) {
 387     _submodel = s;
 388 }
 389
 390 void FGAIBallistic::setFuseRange(double f) {
 391     _fuse_range = f;
 392 }
 393
 394 void FGAIBallistic::setSubID(int i) {
 395     _subID = i;
 396 }
 397
 398 void FGAIBallistic::setSubmodel(const string& s) {
 399     _submodel = s;
 400 }
 401
 402 void FGAIBallistic::setGroundOffset(double g) {
 403     _ground_offset = g;
 404 }
 405
 406 void FGAIBallistic::setLoadOffset(double l) {
 407     _load_offset = l;
 408 }
 409
 410 double FGAIBallistic::getLoadOffset() const {
 411     return _load_offset;
 412 }
 413
 414 void FGAIBallistic::setSlaved(bool s) {
 415     _slave_to_ac = s;
 416 }
 417
 418 void FGAIBallistic::setFormate(bool f) {
 419     _formate_to_ac = f;
 420 }
 421
 422 void FGAIBallistic::setContentsNode(const string& path) {
 423     if (!path.empty()) {
 424         _contents_node = fgGetNode(path.c_str(), true);
 425     }
 426 }
 427
 428 bool FGAIBallistic::getSlaved() const {
 429     return _slave_to_ac;
 430 }
 431
 432 double FGAIBallistic::getMass() const {
 433     return _mass;
 434 }
 435
 436 double FGAIBallistic::getContents() {
 437     if(_contents_node)
 438         _contents_lb = _contents_node->getChild("level-lbs",0,1)->getDoubleValue();
 439     return _contents_lb;
 440 }
 441
 442 void FGAIBallistic::setContents(double c) {
 443     if(_contents_node)
 444         _contents_lb = _contents_node->getChild("level-gal_us",0,1)->setDoubleValue(c);
 445 }
 446
 447 void FGAIBallistic::setSlavedLoad(bool l) {
 448     _slave_load_to_ac = l;
 449 }
 450
 451 bool FGAIBallistic::getSlavedLoad() const {
 452     return _slave_load_to_ac;
 453 }
 454
 455 void FGAIBallistic::setForcePath(const string& p) {
 456     _force_path = p;
 457     if (!_force_path.empty()) {
 458         SGPropertyNode *fnode = fgGetNode(_force_path.c_str(), 0, true );
 459         _force_node = fnode->getChild("force-lb", 0, true);
 460         _force_azimuth_node = fnode->getChild("force-azimuth-deg", 0, true);
 461         _force_elevation_node = fnode->getChild("force-elevation-deg", 0, true);
 462     }
 463 }
 464
 465 bool FGAIBallistic::getHtAGL(){
 466
 467     if (getGroundElevationM(SGGeod::fromGeodM(pos, 10000),
 468                             _elevation_m, &_material)) {
 469             _ht_agl_ft = pos.getElevationFt() - _elevation_m * SG_METER_TO_FEET;
 470             if (_material) {
 471                 const vector<string>& names = _material->get_names();
 472
 473                 _solid = _material->get_solid();
 474                 _load_resistance = _material->get_load_resistance();
 475                 _frictionFactor =_material->get_friction_factor();
 476                 if (!names.empty())
 477                     props->setStringValue("material/name", names[0].c_str());
 478                 else
 479                     props->setStringValue("material/name", "");
 480                 /*cout << "material " << mat_name
 481                 << " solid " << _solid
 482                 << " load " << _load_resistance
 483                 << " frictionFactor " << frictionFactor
 484                 << endl;*/
 485             }
 486             return true;
 487     } else {
 488         return false;
 489     }
 490
 491 }
 492
 493 double FGAIBallistic::getRecip(double az){
 494     // calculate the reciprocal of the input azimuth
 495     if(az - 180 < 0){
 496         return az + 180;
 497     } else {
 498         return az - 180;
 499     }
 500 }
 501
 502 void FGAIBallistic::setPch(double e, double dt, double coeff){
 503     double c = dt / (coeff + dt);
 504     pitch = (e * c) + (pitch * (1 - c));
 505 }
 506
 507 void FGAIBallistic::setBnk(double r, double dt, double coeff){
 508     double c = dt / (coeff + dt);
 509     roll = (r * c) + (roll * (1 - c));
 510 }
 511
 512 void FGAIBallistic::setHt(double h, double dt, double coeff){
 513     double c = dt / (coeff + dt);
 514     _height = (h * c) + (_height * (1 - c));
 515 }
 516
 517 void FGAIBallistic::setHdg(double az, double dt, double coeff){
 518         double recip = getRecip(hdg);
 519         double c = dt / (coeff + dt);
 520         //we need to ensure that we turn the short way to the new hdg
 521         if (az < recip && az < hdg && hdg > 180) {
 522                 hdg = ((az + 360) * c) + (hdg * (1 - c));
 523         } else if (az > recip && az > hdg && hdg <= 180){
 524                 hdg = ((az - 360) * c) + (hdg * (1 - c));
 525         } else {
 526                 hdg = (az * c) + (hdg * (1 - c));
 527         }
 528 }
 529
 530 double  FGAIBallistic::getTgtXOffset() const {
 531     return _tgt_x_offset;
 532 }
 533
 534 double  FGAIBallistic::getTgtYOffset() const {
 535     return _tgt_y_offset;
 536 }
 537
 538 double  FGAIBallistic::getTgtZOffset() const {
 539     return _tgt_z_offset;
 540 }
 541
 542 void FGAIBallistic::setTgtXOffset(double x){
 543     _tgt_x_offset = x;
 544 }
 545
 546 void FGAIBallistic::setTgtYOffset(double y){
 547     _tgt_y_offset = y;
 548 }
 549
 550 void FGAIBallistic::setTgtZOffset(double z){
 551     _tgt_z_offset = z;
 552 }
 553
 554 void FGAIBallistic::slaveToAC(double dt){
 555
 556     setHitchPos();
 557     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 558     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 559     pos.setElevationFt(hitchpos.getElevationFt());
 560     setHeading(manager->get_user_heading());
 561     setPitch(manager->get_user_pitch() + _pitch_offset);
 562     setBank(manager->get_user_roll() + _roll_offset);
 563     setSpeed(manager->get_user_speed());
 564     //update the mass (slugs)
 565     _mass = (_weight_lb + getContents()) / slugs_to_lbs;
 566
 567     /*cout <<"_mass "<<_mass <<" " << getContents()
 568     <<" " << getContents() / slugs_to_lbs << endl;*/
 569 }
 570
 571 void FGAIBallistic::Run(double dt) {
 572     _life_timer += dt;
 573
 574     // if life = -1 the object does not die
 575         if (_life_timer > life && life != -1){
 576
 577                 if (_report_expiry && !_expiry_reported){
 578                         //cout<<"AIBallistic: expiry"<< endl;
 579                         handle_expiry();
 580                 } else
 581                         setDie(true);
 582
 583         }
 584
 585     //set the contents in the appropriate tank or other property in the parent to zero
 586     setContents(0);
 587
 588     //randomise Cd by +- 10%
 589     if (_random)
 590         _Cd = _Cd * 0.90 + (0.10 * sg_random());
 591
 592     // Adjust Cd by Mach number. The equations are based on curves
 593     // for a conventional shell/bullet (no boat-tail).
 594     double Cdm;
 595
 596     if (Mach < 0.7)
 597         Cdm = 0.0125 * Mach + _Cd;
 598     else if (Mach < 1.2 )
 599         Cdm = 0.3742 * pow(Mach, 2) - 0.252 * Mach + 0.0021 + _Cd;
 600     else
 601         Cdm = 0.2965 * pow(Mach, -1.1506) + _Cd;
 602
 603     //cout << "Mach " << Mach << " Cdm " << Cdm << "// ballistic speed kts "<< speed <<  endl;
 604
 605     // drag = Cd * 0.5 * rho * speed * speed * drag_area;
 606     // rho is adjusted for altitude in void FGAIBase::update,
 607     // using Standard Atmosphere (sealevel temperature 15C)
 608     // acceleration = drag/mass;
 609     // adjust speed by drag
 610     speed -= (Cdm * 0.5 * rho * speed * speed * _drag_area/_mass) * dt;
 611
 612     // don't let speed become negative
 613     if ( speed < 0.0 )
 614         speed = 0.0;
 615
 616     double speed_fps = speed * SG_KT_TO_FPS;
 617     //double hs;
 618
 619     // calculate vertical and horizontal speed components
 620     if (speed == 0.0) {
 621         hs = vs = 0.0;
 622     } else {
 623         vs = sin( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 624         hs = cos( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 625     }
 626
 627     //resolve horizontal speed into north and east components:
 628     double speed_north_fps = cos(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 629     double speed_east_fps = sin(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 630
 631     // convert horizontal speed (fps) to degrees per second
 632     double speed_north_deg_sec = speed_north_fps / ft_per_deg_lat;
 633     double speed_east_deg_sec  = speed_east_fps / ft_per_deg_lon;
 634
 635     // if wind not required, set to zero
 636     if (!_wind) {
 637         _wind_from_north = 0;
 638         _wind_from_east = 0;
 639     } else {
 640         _wind_from_north = manager->get_wind_from_north();
 641         _wind_from_east = manager->get_wind_from_east();
 642     }
 643
 644     //calculate velocity due to external force
 645     double force_speed_north_deg_sec = 0;
 646     double force_speed_east_deg_sec = 0;
 647 //    double vs_force_fps = 0;
 648     double hs_force_fps = 0;
 649     double v_force_acc_fpss = 0;
 650     double force_speed_north_fps = 0;
 651     double force_speed_east_fps = 0;
 652     double h_force_lbs = 0;
 653     double normal_force_lbs = 0;
 654     double normal_force_fpss = 0;
 655     double static_friction_force_lbs = 0;
 656     double dynamic_friction_force_lbs = 0;
 657     double friction_force_speed_north_fps = 0;
 658     double friction_force_speed_east_fps = 0;
 659     double friction_force_speed_north_deg_sec = 0;
 660     double friction_force_speed_east_deg_sec = 0;
 661     double force_elevation_deg = 0;
 662
 663         if (_external_force) {
 664
 665         SGPropertyNode *n = fgGetNode(_force_path.c_str(), true);
 666         double force_lbs            = n->getChild("force-lb", 0, true)->getDoubleValue();
 667         force_elevation_deg         = n->getChild("force-elevation-deg", 0, true)->getDoubleValue();
 668         double force_azimuth_deg    = n->getChild("force-azimuth-deg", 0, true)->getDoubleValue();
 669
 670         //resolve force into vertical and horizontal components:
 671         double v_force_lbs = force_lbs * sin( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 672         h_force_lbs = force_lbs * cos( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 673
 674         //ground interaction
 675
 676         if (getHtAGL()){
 677             double deadzone = 0.1;
 678
 679             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 680                 normal_force_lbs = (_mass * slugs_to_lbs) - v_force_lbs;
 681
 682                 if ( normal_force_lbs < 0 )
 683                     normal_force_lbs = 0;
 684
 685                 pos.setElevationFt(0 + _ground_offset);
 686                 if (vs < 0)
 687                     vs = -vs * 0.5;
 688
 689                 // calculate friction
 690                 // we assume a static Coefficient of Friction (mu) of 0.62 (wood on concrete)
 691                 double mu = 0.62;
 692
 693                 static_friction_force_lbs = mu * normal_force_lbs * _frictionFactor;
 694
 695                 //adjust horizontal force. We assume that a speed of <= 5 fps is static
 696                 if (h_force_lbs <= static_friction_force_lbs && hs <= 5){
 697                     h_force_lbs = hs = 0;
 698                     speed_north_fps = speed_east_fps = 0;
 699                 } else
 700                     dynamic_friction_force_lbs = (static_friction_force_lbs * 0.95);
 701
 702                 //ignore wind when on the ground for now
 703                 //TODO fix this
 704                 _wind_from_north = 0;
 705                 _wind_from_east = 0;
 706
 707             }
 708
 709         }
 710
 711         //acceleration = (force(lbsf)/mass(slugs))
 712         v_force_acc_fpss = v_force_lbs/_mass;
 713         normal_force_fpss = normal_force_lbs/_mass;
 714         double h_force_acc_fpss = h_force_lbs/_mass;
 715         double dynamic_friction_acc_fpss = dynamic_friction_force_lbs/_mass;
 716
 717         // velocity = acceleration * dt
 718         hs_force_fps = h_force_acc_fpss * dt;
 719         double friction_force_fps = dynamic_friction_acc_fpss * dt;
 720
 721         //resolve horizontal speeds into north and east components:
 722         force_speed_north_fps   = cos(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 723         force_speed_east_fps    = sin(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 724
 725         friction_force_speed_north_fps = cos(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 726         friction_force_speed_east_fps  = sin(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 727
 728         // convert horizontal speed (fps) to degrees per second
 729         force_speed_north_deg_sec = force_speed_north_fps / ft_per_deg_lat;
 730         force_speed_east_deg_sec  = force_speed_east_fps / ft_per_deg_lon;
 731
 732         friction_force_speed_north_deg_sec = friction_force_speed_north_fps / ft_per_deg_lat;
 733         friction_force_speed_east_deg_sec  = friction_force_speed_east_fps / ft_per_deg_lon;
 734     }
 735
 736     // convert wind speed (fps) to degrees lat/lon per second
 737     double wind_speed_from_north_deg_sec = _wind_from_north / ft_per_deg_lat;
 738     double wind_speed_from_east_deg_sec  = _wind_from_east / ft_per_deg_lon;
 739
 740     //recombine the horizontal velocity components
 741     hs = sqrt(((speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps)
 742         * (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 743         + ((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)
 744         * (speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)));
 745
 746     if (hs <= 0.00001)
 747         hs = 0;
 748
 749     // adjust vertical speed for acceleration of gravity, buoyancy, and vertical force
 750     vs -= (_gravity - _buoyancy - v_force_acc_fpss - normal_force_fpss) * dt;
 751
 752     if (vs <= 0.00001 && vs >= -0.00001)
 753         vs = 0;
 754
 755     // set new position
 756     if(_slave_load_to_ac) {
 757         setHitchPos();
 758         pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 759         pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 760         pos.setElevationFt(hitchpos.getElevationFt());
 761
 762         if (getHtAGL()){
 763             double deadzone = 0.1;
 764
 765             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 766                 pos.setElevationFt(0 + _ground_offset);
 767             } else {
 768                 pos.setElevationFt(hitchpos.getElevationFt() + _load_offset);
 769             }
 770
 771         }
 772     } else {
 773         pos.setLatitudeDeg( pos.getLatitudeDeg()
 774             + (speed_north_deg_sec - wind_speed_from_north_deg_sec
 775             + force_speed_north_deg_sec + friction_force_speed_north_deg_sec) * dt );
 776         pos.setLongitudeDeg( pos.getLongitudeDeg()
 777             + (speed_east_deg_sec - wind_speed_from_east_deg_sec
 778             + force_speed_east_deg_sec + friction_force_speed_east_deg_sec) * dt );
 779         pos.setElevationFt(pos.getElevationFt() + vs * dt);
 780     }
 781
 782     // recalculate total speed
 783     if ( vs == 0 && hs == 0)
 784         speed = 0;
 785     else
 786         speed = sqrt( vs * vs + hs * hs) / SG_KT_TO_FPS;
 787
 788     // recalculate elevation and azimuth (velocity vectors)
 789     _elevation = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
 790     _azimuth =  atan2((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps),
 791         (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 792         * SG_RADIANS_TO_DEGREES;
 793
 794     // rationalise azimuth
 795     if (_azimuth < 0)
 796         _azimuth += 360;
 797
 798         //cout << "_azimuth " << _azimuth << " hdg "<<  hdg << endl;
 799
 800     if (_aero_stabilised) { // we simulate rotational moment of inertia by using a filter
 801                 //cout<< "_aero_stabilised "<< endl;
 802         const double coeff = 0.9;
 803
 804         // we assume a symetrical MI about the pitch and yaw axis
 805         setPch(_elevation, dt, coeff);
 806         setHdg(_azimuth, dt, coeff);
 807     } else if (_force_stabilised) { // we simulate rotational moment of inertia by using a filter
 808         //cout<< "_force_stabilised "<< endl;
 809
 810                 const double coeff = 0.9;
 811         double ratio = h_force_lbs/(_mass * slugs_to_lbs);
 812
 813         if (ratio >  1) ratio =  1;
 814         if (ratio < -1) ratio = -1;
 815
 816         double force_pitch = acos(ratio) * SG_RADIANS_TO_DEGREES;
 817
 818         if (force_pitch <= force_elevation_deg)
 819             force_pitch = force_elevation_deg;
 820
 821         // we assume a symetrical MI about the pitch and yaw axis
 822         setPch(force_pitch,dt, coeff);
 823         setHdg(_azimuth, dt, coeff);
 824     }
 825
 826     //do impacts and collisions
 827     if (_report_impact && !_impact_reported)
 828         handle_impact();
 829
 830     if (_report_collision && !_collision_reported)
 831         handle_collision();
 832
 833     // set destruction flag if altitude less than sea level -1000
 834     if (altitude_ft < -1000.0 && life != -1)
 835         setDie(true);
 836
 837 }  // end Run
 838
 839 double FGAIBallistic::_getTime() const {
 840     return _life_timer;
 841 }
 842
 843 void FGAIBallistic::handle_impact() {
 844
 845     // try terrain intersection
 846     if(!getHtAGL())
 847         return;
 848
 849     if (_ht_agl_ft <= 0) {
 850         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: terrain impact");
 851         report_impact(_elevation_m);
 852         _impact_reported = true;
 853
 854         if (life == -1){
 855             invisible = true;
 856         } else if (_subID == 0)  // kill the AIObject if there is no subsubmodel
 857             setDie(true);
 858     }
 859 }
 860
 861 void FGAIBallistic::handle_expiry() {
 862
 863                 SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: handle_expiry " << pos.getElevationM());
 864
 865         report_impact(pos.getElevationM());
 866         _expiry_reported = true;
 867
 868         //if (life == -1){
 869         //    invisible = true;
 870         //} else if (_subID == 0)  // kill the AIObject if there is no subsubmodel
 871         //    setDie(true);
 872
 873 }
 874
 875 void FGAIBallistic::handle_collision()
 876 {
 877     const FGAIBase *object = manager->calcCollision(pos.getElevationFt(),
 878             pos.getLatitudeDeg(),pos.getLongitudeDeg(), _fuse_range);
 879
 880     if (object) {
 881         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: object hit");
 882         report_impact(pos.getElevationM(), object);
 883         _collision_reported = true;
 884     }
 885 }
 886
 887 void FGAIBallistic::report_impact(double elevation, const FGAIBase *object)
 888 {
 889     _impact_lat    = pos.getLatitudeDeg();
 890     _impact_lon    = pos.getLongitudeDeg();
 891     _impact_elev   = elevation;
 892     _impact_speed  = speed * SG_KT_TO_MPS;
 893     _impact_hdg    = hdg;
 894     _impact_pitch  = pitch;
 895     _impact_roll   = roll;
 896
 897     SGPropertyNode *n = props->getNode("impact", true);
 898     if (object)
 899         n->setStringValue("type", object->getTypeString());
 900     else
 901         n->setStringValue("type", "terrain");
 902
 903     n->setDoubleValue("longitude-deg", _impact_lon);
 904     n->setDoubleValue("latitude-deg", _impact_lat);
 905     n->setDoubleValue("elevation-m", _impact_elev);
 906     n->setDoubleValue("heading-deg", _impact_hdg);
 907     n->setDoubleValue("pitch-deg", _impact_pitch);
 908     n->setDoubleValue("roll-deg", _impact_roll);
 909     n->setDoubleValue("speed-mps", _impact_speed);
 910
 911     _impact_report_node->setStringValue(props->getPath());
 912 }
 913
 914 SGVec3d FGAIBallistic::getCartUserPos() const {
 915     SGVec3d cartUserPos = SGVec3d::fromGeod(userpos);
 916     return cartUserPos;
 917 }
 918
 919 SGVec3d FGAIBallistic::getCartHitchPos() const{
 920
 921     // convert geodetic positions to geocentered
 922     SGVec3d cartuserPos = getCartUserPos();
 923     //SGVec3d cartPos = getCartPos();
 924
 925     // Transform to the right coordinate frame, configuration is done in
 926     // the x-forward, y-right, z-up coordinates (feet), computation
 927     // in the simulation usual body x-forward, y-right, z-down coordinates
 928     // (meters) )
 929     SGVec3d _off(_x_offset * SG_FEET_TO_METER,
 930         _y_offset * SG_FEET_TO_METER,
 931         -_z_offset * SG_FEET_TO_METER);
 932
 933     // Transform the user position to the horizontal local coordinate system.
 934     SGQuatd hlTrans = SGQuatd::fromLonLat(userpos);
 935
 936     // and postrotate the orientation of the user model wrt the horizontal
 937     // local frame
 938     hlTrans *= SGQuatd::fromYawPitchRollDeg(
 939         manager->get_user_heading(),
 940         manager->get_user_pitch(),
 941         manager->get_user_roll());
 942
 943     // The offset converted to the usual body fixed coordinate system
 944     // rotated to the earth-fixed coordinates axis
 945     SGVec3d off = hlTrans.backTransform(_off);
 946
 947     // Add the position offset of the user model to get the geocentered position
 948     SGVec3d offsetPos = cartuserPos + off;
 949
 950     return offsetPos;
 951 }
 952
 953 void FGAIBallistic::setHitchPos(){
 954     // convert the hitch geocentered position to geodetic
 955     SGVec3d carthitchPos = getCartHitchPos();
 956
 957     SGGeodesy::SGCartToGeod(carthitchPos, hitchpos);
 958 }
 959
 960 double FGAIBallistic::getDistanceLoadToHitch() const {
 961     //calculate the distance load to hitch
 962     SGVec3d carthitchPos = getCartHitchPos();
 963     SGVec3d cartPos = getCartPos();
 964
 965     SGVec3d diff = carthitchPos - cartPos;
 966     double distance = norm(diff);
 967     return distance * SG_METER_TO_FEET;
 968 }
 969
 970 void FGAIBallistic::setHitchVelocity(double dt) {
 971     //calculate the distance from the previous hitch position
 972     SGVec3d carthitchPos = getCartHitchPos();
 973     SGVec3d diff = carthitchPos - _oldcarthitchPos;
 974
 975     double distance = norm(diff);
 976
 977     //calculate speed knots
 978     speed = (distance/dt) * SG_MPS_TO_KT;
 979
 980     //now calulate the angle between the old and current hitch positions (degrees)
 981     double angle = 0;
 982     double daltM = hitchpos.getElevationM() - oldhitchpos.getElevationM();
 983
 984     if (fabs(distance) < SGLimits<float>::min()) {
 985         angle = 0;
 986     } else {
 987         double sAngle = daltM/distance;
 988         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 989         angle = SGMiscd::rad2deg(asin(sAngle));
 990     }
 991
 992     _elevation = angle;
 993
 994     //calculate the bearing of the new hitch position from the old
 995     double az1, az2, dist;
 996
 997     geo_inverse_wgs_84(oldhitchpos, hitchpos, &az1, &az2, &dist);
 998
 999     _azimuth = az1;
1000
1001     // and finally store the new values
1002     _oldcarthitchPos = carthitchPos;
1003     oldhitchpos = hitchpos;
1004 }
1005
1006 double FGAIBallistic::getElevLoadToHitch() const {
1007     // now the angle, positive angles are upwards
1008     double distance = getDistanceLoadToHitch() * SG_FEET_TO_METER;
1009     double angle = 0;
1010     double daltM = hitchpos.getElevationM() - pos.getElevationM();
1011
1012     if (fabs(distance) < SGLimits<float>::min()) {
1013         angle = 0;
1014     } else {
1015         double sAngle = daltM/distance;
1016         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
1017         angle = SGMiscd::rad2deg(asin(sAngle));
1018     }
1019
1020     return angle;
1021 }
1022
1023 double FGAIBallistic::getBearingLoadToHitch() const {
1024     //calculate the bearing and range of the second pos from the first
1025     double az1, az2, distance;
1026
1027     geo_inverse_wgs_84(pos, hitchpos, &az1, &az2, &distance);
1028
1029     return az1;
1030 }
1031
1032 double FGAIBallistic::getRelBrgHitchToUser() const {
1033     //calculate the relative bearing
1034     double az1, az2, distance;
1035
1036     geo_inverse_wgs_84(hitchpos, userpos, &az1, &az2, &distance);
1037
1038     double rel_brg = az1 - hdg;
1039
1040     if (rel_brg > 180)
1041         rel_brg -= 360;
1042
1043     return rel_brg;
1044 }
1045
1046 double FGAIBallistic::getElevHitchToUser() const {
1047
1048     //calculate the distance from the user position
1049     SGVec3d carthitchPos = getCartHitchPos();
1050     SGVec3d cartuserPos = getCartUserPos();
1051
1052     SGVec3d diff = cartuserPos - carthitchPos;
1053
1054     double distance = norm(diff);
1055     double angle = 0;
1056
1057     double daltM = userpos.getElevationM() - hitchpos.getElevationM();
1058
1059     // now the angle, positive angles are upwards
1060     if (fabs(distance) < SGLimits<float>::min()) {
1061         angle = 0;
1062     } else {
1063         double sAngle = daltM/distance;
1064         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
1065         angle = SGMiscd::rad2deg(asin(sAngle));
1066     }
1067
1068     return angle;
1069 }
1070
1071 void FGAIBallistic::setTgtOffsets(double dt, double coeff){
1072     double c = dt / (coeff + dt);
1073
1074     _x_offset = (_tgt_x_offset * c) + (_x_offset * (1 - c));
1075     _y_offset = (_tgt_y_offset * c) + (_y_offset * (1 - c));
1076     _z_offset = (_tgt_z_offset * c) + (_z_offset * (1 - c));
1077 }
1078
1079 void FGAIBallistic::formateToAC(double dt){
1080
1081     setTgtOffsets(dt, 25);
1082     setHitchPos();
1083     setHitchVelocity(dt);
1084
1085     // elapsed time has a random initialisation so that each
1086     // wingman moves differently
1087     _elapsed_time += dt;
1088
1089     // we derive a sine based factor to give us smoothly
1090     // varying error between -1 and 1
1091     double factor  = sin(SGMiscd::deg2rad(_elapsed_time * 10));
1092     double r_angle = 5 * factor;
1093     double p_angle = 2.5 * factor;
1094     double h_angle = 5 * factor;
1095     double h_feet  = 3 * factor;
1096
1097     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
1098     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
1099
1100     if (getHtAGL()){
1101
1102         if(_ht_agl_ft <= 10) {
1103             _height = userpos.getElevationFt();
1104         } else if (_ht_agl_ft > 10 && _ht_agl_ft <= 150 ) {
1105             setHt(userpos.getElevationFt(), dt, 1.0);
1106         } else if (_ht_agl_ft > 150 && _ht_agl_ft <= 250) {
1107             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.75);
1108         } else
1109             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.5);
1110
1111         pos.setElevationFt(_height);
1112     }
1113
1114     // these calculations are unreliable at slow speeds
1115     if(speed >= 10) {
1116         setHdg(_azimuth + h_angle, dt, 0.9);
1117         setPch(_elevation + p_angle + _pitch_offset, dt, 0.9);
1118
1119         if (roll <= 115 && roll >= -115)
1120             setBnk(manager->get_user_roll() + r_angle + _roll_offset, dt, 0.5);
1121         else
1122             roll = manager->get_user_roll() + r_angle + _roll_offset;
1123
1124     } else {
1125         setHdg(manager->get_user_heading(), dt, 0.9);
1126         setPch(manager->get_user_pitch() + _pitch_offset, dt, 0.9);
1127         setBnk(manager->get_user_roll() + _roll_offset, dt, 0.9);
1128     }
1129
1130     setSpeed(speed);
1131 }
1132 // end AIBallistic