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/point3d.hxx>
  27 #include <simgear/math/sg_random.h>
  28 #include <simgear/math/sg_geodesy.hxx>
  29
  30 #include <Scenery/scenery.hxx>
  31
  32 #include "AIBallistic.hxx"
  33
  34 #include <Main/util.hxx>
  35
  36 const double FGAIBallistic::slugs_to_kgs = 14.5939029372;
  37 const double FGAIBallistic::slugs_to_lbs = 32.1740485564;
  38
  39 FGAIBallistic::FGAIBallistic(object_type ot) :
  40 FGAIBase(ot),
  41     _elevation(0),
  42     _aero_stabilised(false),
  43     _drag_area(0.007),
  44     _life_timer(0.0),
  45 _gravity(32.1740485564),
  46     _buoyancy(0),
  47     _random(false),
  48     _ht_agl_ft(0),
  49     _load_resistance(0),
  50     _solid(false),
  51     _report_collision(false),
  52     _report_impact(false),
  53 _wind(true),
  54     _impact_report_node(fgGetNode("/ai/models/model-impact", true)),
  55 _external_force(false),
  56 _slave_to_ac(false),
  57 _slave_load_to_ac(false),
  58 _formate_to_ac(false),
  59 _contents_lb(0),
  60 _mass(0),
  61 _height(0),
  62 _old_height(0)
  63
  64 {
  65     no_roll = false;
  66 }
  67
  68 FGAIBallistic::~FGAIBallistic() {
  69 }
  70
  71 void FGAIBallistic::readFromScenario(SGPropertyNode* scFileNode) {
  72     if (!scFileNode){
  73         return;
  74     }
  75
  76     FGAIBase::readFromScenario(scFileNode);
  77
  78     //setPath(scFileNode->getStringValue("model", "Models/Geometry/rocket.ac"));
  79     setAzimuth(scFileNode->getDoubleValue("azimuth", 0.0));
  80     setElevation(scFileNode->getDoubleValue("elevation", 0));
  81     setDragArea(scFileNode->getDoubleValue("eda", 0.007));
  82     setLife(scFileNode->getDoubleValue("life", 900.0));
  83     setBuoyancy(scFileNode->getDoubleValue("buoyancy", 0));
  84     setWind_from_east(scFileNode->getDoubleValue("wind_from_east", 0));
  85     setWind_from_north(scFileNode->getDoubleValue("wind_from_north", 0));
  86     setWind(scFileNode->getBoolValue("wind", false));
  87     setRoll(scFileNode->getDoubleValue("roll", 0.0));
  88     setCd(scFileNode->getDoubleValue("cd", 0.029));
  89     //setMass(scFileNode->getDoubleValue("mass", 0.007));
  90     setWeight(scFileNode->getDoubleValue("weight", 0.25));
  91     setStabilisation(scFileNode->getBoolValue("aero_stabilized", false));
  92     setNoRoll(scFileNode->getBoolValue("no-roll", false));
  93     setRandom(scFileNode->getBoolValue("random", false));
  94     setImpact(scFileNode->getBoolValue("impact", false));
  95     setImpactReportNode(scFileNode->getStringValue("impact-reports"));
  96     setName(scFileNode->getStringValue("name", "Rocket"));
  97     setFuseRange(scFileNode->getDoubleValue("fuse-range", 0.0));
  98     setSMPath(scFileNode->getStringValue("submodel-path", ""));
  99     setSubID(scFileNode->getIntValue("SubID", 0));
 100     setExternalForce(scFileNode->getBoolValue("external-force", false));
 101     setForcePath(scFileNode->getStringValue("force-path", ""));
 102     setForceStabilisation(scFileNode->getBoolValue("force_stabilized", false));
 103     setXoffset(scFileNode->getDoubleValue("x-offset", 0.0));
 104     setYoffset(scFileNode->getDoubleValue("y-offset", 0.0));
 105     setZoffset(scFileNode->getDoubleValue("z-offset", 0.0));
 106     setPitchoffset(scFileNode->getDoubleValue("pitch-offset", 0.0));
 107     setRolloffset(scFileNode->getDoubleValue("roll-offset", 0.0));
 108     setYawoffset(scFileNode->getDoubleValue("yaw-offset", 0.0));
 109     setGroundOffset(scFileNode->getDoubleValue("ground-offset", 0.0));
 110     setLoadOffset(scFileNode->getDoubleValue("load-offset", 0.0));
 111     setSlaved(scFileNode->getBoolValue("slaved", false));
 112     setSlavedLoad(scFileNode->getBoolValue("slaved-load", false));
 113     setContentsNode(scFileNode->getStringValue("contents"));
 114     setRandom(scFileNode->getBoolValue("random", false));
 115 }
 116
 117 bool FGAIBallistic::init(bool search_in_AI_path) {
 118     FGAIBase::init(search_in_AI_path);
 119
 120     _impact_reported = false;
 121     _collision_reported = false;
 122     invisible = false;
 123
 124     _elapsed_time += (sg_random() * 100);
 125
 126     props->setStringValue("material/name", "");
 127     props->setStringValue("name", _name.c_str());
 128     props->setStringValue("submodels/path", _submodel.c_str());
 129
 130     // start with high value so that animations don't trigger yet
 131     _ht_agl_ft = 1e10;
 132     hdg = _azimuth;
 133     pitch = _elevation;
 134     roll = _rotation;
 135
 136     Transform();
 137
 138     return true;
 139 }
 140
 141 void FGAIBallistic::bind() {
 142     //    FGAIBase::bind();
 143
 144     props->tie("sim/time/elapsed-sec",
 145         SGRawValueMethods<FGAIBallistic,double>(*this,
 146         &FGAIBallistic::_getTime));
 147     props->tie("mass-slug",
 148         SGRawValueMethods<FGAIBallistic,double>(*this,
 149         &FGAIBallistic::getMass));
 150     props->tie("material/load-resistance",
 151                 SGRawValuePointer<double>(&_load_resistance));
 152     props->tie("material/solid",
 153                 SGRawValuePointer<bool>(&_solid));
 154     props->tie("altitude-agl-ft",
 155                 SGRawValuePointer<double>(&_ht_agl_ft));
 156     props->tie("controls/slave-to-ac",
 157         SGRawValueMethods<FGAIBallistic,bool>
 158         (*this, &FGAIBallistic::getSlaved, &FGAIBallistic::setSlaved));
 159     props->tie("controls/invisible",
 160         SGRawValuePointer<bool>(&invisible));
 161
 162     if(_external_force){
 163         props->tie("controls/force_stabilized",
 164             SGRawValuePointer<bool>(&_force_stabilised));
 165         props->tie("position/global-x",
 166             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosX, 0));
 167         props->tie("position/global-y",
 168             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosY, 0));
 169         props->tie("position/global-z",
 170             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosZ, 0));
 171         props->tie("velocities/vertical-speed-fps",
 172             SGRawValuePointer<double>(&vs));
 173         props->tie("velocities/true-airspeed-kt",
 174             SGRawValuePointer<double>(&speed));
 175         props->tie("velocities/horizontal-speed-fps",
 176             SGRawValuePointer<double>(&hs));
 177         props->tie("position/altitude-ft",
 178             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getAltitude, &FGAIBase::_setAltitude));
 179         props->tie("position/latitude-deg",
 180             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLatitude, &FGAIBase::_setLatitude));
 181         props->tie("position/longitude-deg",
 182             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLongitude, &FGAIBase::_setLongitude));
 183         props->tie("orientation/hdg-deg",
 184             SGRawValuePointer<double>(&hdg));
 185         props->tie("orientation/pitch-deg",
 186             SGRawValuePointer<double>(&pitch));
 187         props->tie("orientation/roll-deg",
 188             SGRawValuePointer<double>(&roll));
 189         props->tie("controls/slave-load-to-ac",
 190             SGRawValueMethods<FGAIBallistic,bool>
 191             (*this, &FGAIBallistic::getSlavedLoad, &FGAIBallistic::setSlavedLoad));
 192         props->tie("position/load-offset",
 193             SGRawValueMethods<FGAIBallistic,double>
 194             (*this, &FGAIBallistic::getLoadOffset, &FGAIBallistic::setLoadOffset));
 195         props->tie("load/distance-to-hitch-ft",
 196             SGRawValueMethods<FGAIBallistic,double>
 197             (*this, &FGAIBallistic::getDistanceLoadToHitch));
 198         props->tie("load/elevation-to-hitch-deg",
 199             SGRawValueMethods<FGAIBallistic,double>
 200             (*this, &FGAIBallistic::getElevLoadToHitch));
 201         props->tie("load/bearing-to-hitch-deg",
 202             SGRawValueMethods<FGAIBallistic,double>
 203             (*this, &FGAIBallistic::getBearingLoadToHitch));
 204     }
 205
 206 }
 207
 208 void FGAIBallistic::unbind() {
 209     //    FGAIBase::unbind();
 210
 211     props->untie("sim/time/elapsed-sec");
 212     props->untie("mass-slug");
 213     props->untie("material/load-resistance");
 214     props->untie("material/solid");
 215     props->untie("altitude-agl-ft");
 216     props->untie("controls/slave-to-ac");
 217     props->untie("controls/invisible");
 218
 219     if(_external_force){
 220         props->untie("position/global-y");
 221         props->untie("position/global-x");
 222         props->untie("position/global-z");
 223         props->untie("velocities/vertical-speed-fps");
 224         props->untie("velocities/true-airspeed-kt");
 225         props->untie("velocities/horizontal-speed-fps");
 226         props->untie("position/altitude-ft");
 227         props->untie("position/latitude-deg");
 228         props->untie("position/longitude-deg");
 229         props->untie("position/ht-agl-ft");
 230         props->untie("orientation/hdg-deg");
 231         props->untie("orientation/pitch-deg");
 232         props->untie("orientation/roll-deg");
 233         props->untie("controls/force_stabilized");
 234         props->untie("position/load-offset");
 235         props->untie("load/distance-to-hitch-ft");
 236         props->untie("load/elevation-to-hitch-deg");
 237         props->untie("load/bearing-to-hitch-deg");
 238     }
 239 }
 240
 241 void FGAIBallistic::update(double dt) {
 242     FGAIBase::update(dt);
 243     _setUserPos();
 244
 245     if (_slave_to_ac){
 246         slaveToAC(dt);
 247         Transform();
 248         setHitchVelocity(dt);
 249     } else if (_formate_to_ac){
 250         formateToAC(dt);
 251         Transform();
 252         setHitchVelocity(dt);
 253     } else if (!invisible){
 254     Run(dt);
 255     Transform();
 256 }
 257
 258 }
 259
 260 void FGAIBallistic::setAzimuth(double az) {
 261     hdg = _azimuth = az;
 262 }
 263
 264 void FGAIBallistic::setElevation(double el) {
 265     pitch = _elevation = el;
 266 }
 267
 268 void FGAIBallistic::setRoll(double rl) {
 269     roll = _rotation = rl;
 270 }
 271
 272 void FGAIBallistic::setStabilisation(bool val) {
 273     _aero_stabilised = val;
 274 }
 275
 276 void FGAIBallistic::setForceStabilisation(bool val) {
 277     _force_stabilised = val;
 278 }
 279
 280 void FGAIBallistic::setNoRoll(bool nr) {
 281     no_roll = nr;
 282 }
 283
 284 void FGAIBallistic::setDragArea(double a) {
 285     _drag_area = a;
 286 }
 287
 288 void FGAIBallistic::setLife(double seconds) {
 289     life = seconds;
 290 }
 291
 292 void FGAIBallistic::setBuoyancy(double fpss) {
 293     _buoyancy = fpss;
 294 }
 295
 296 void FGAIBallistic::setWind_from_east(double fps) {
 297     _wind_from_east = fps;
 298 }
 299
 300 void FGAIBallistic::setWind_from_north(double fps) {
 301     _wind_from_north = fps;
 302 }
 303
 304 void FGAIBallistic::setWind(bool val) {
 305     _wind = val;
 306 }
 307
 308 void FGAIBallistic::setCd(double c) {
 309     _Cd = c;
 310 }
 311
 312 void FGAIBallistic::setMass(double m) {
 313     _mass = m;
 314 }
 315
 316 void FGAIBallistic::setWeight(double w) {
 317     _weight_lb = w;
 318 }
 319 void FGAIBallistic::setRandom(bool r) {
 320     _random = r;
 321 }
 322
 323 void FGAIBallistic::setImpact(bool i) {
 324     _report_impact = i;
 325 }
 326
 327 void FGAIBallistic::setCollision(bool c) {
 328     _report_collision = c;
 329 }
 330
 331 void FGAIBallistic::setExternalForce(bool f) {
 332     _external_force = f;
 333 }
 334
 335 void FGAIBallistic::setImpactReportNode(const string& path) {
 336
 337     if (!path.empty())
 338         _impact_report_node = fgGetNode(path.c_str(), true);
 339 }
 340
 341 void FGAIBallistic::setName(const string& n) {
 342     _name = n;
 343 }
 344
 345 void FGAIBallistic::setSMPath(const string& s) {
 346     _submodel = s;
 347 }
 348
 349 void FGAIBallistic::setFuseRange(double f) {
 350     _fuse_range = f;
 351 }
 352
 353 void FGAIBallistic::setSubID(int i) {
 354     _subID = i;
 355 }
 356
 357 void FGAIBallistic::setSubmodel(const string& s) {
 358     _submodel = s;
 359 }
 360
 361 void FGAIBallistic::setGroundOffset(double g) {
 362     _ground_offset = g;
 363 }
 364
 365 void FGAIBallistic::setLoadOffset(double l) {
 366     _load_offset = l;
 367 }
 368
 369 double FGAIBallistic::getLoadOffset() const {
 370     return _load_offset;
 371 }
 372
 373 void FGAIBallistic::setSlaved(bool s) {
 374     _slave_to_ac = s;
 375 }
 376
 377 void FGAIBallistic::setFormate(bool f) {
 378     _formate_to_ac = f;
 379 }
 380
 381 void FGAIBallistic::setContentsNode(const string& path) {
 382     if (!path.empty()) {
 383         _contents_node = fgGetNode(path.c_str(), true);
 384     }
 385 }
 386
 387 bool FGAIBallistic::getSlaved() const {
 388     return _slave_to_ac;
 389 }
 390
 391 double FGAIBallistic::getMass() const {
 392     return _mass;
 393 }
 394
 395 double FGAIBallistic::getContents() {
 396     if(_contents_node)
 397         _contents_lb = _contents_node->getChild("level-lbs",0,1)->getDoubleValue();
 398     return _contents_lb;
 399 }
 400
 401 void FGAIBallistic::setContents(double c) {
 402     if(_contents_node)
 403         _contents_lb = _contents_node->getChild("level-gal_us",0,1)->setDoubleValue(c);
 404 }
 405
 406 void FGAIBallistic::setSlavedLoad(bool l) {
 407     _slave_load_to_ac = l;
 408 }
 409
 410 bool FGAIBallistic::getSlavedLoad() const {
 411     return _slave_load_to_ac;
 412 }
 413
 414 void FGAIBallistic::setForcePath(const string& p) {
 415     _force_path = p;
 416     if (!_force_path.empty()) {
 417         SGPropertyNode *fnode = fgGetNode(_force_path.c_str(), 0, true );
 418         _force_node = fnode->getChild("force-lb", 0, true);
 419         _force_azimuth_node = fnode->getChild("force-azimuth-deg", 0, true);
 420         _force_elevation_node = fnode->getChild("force-elevation-deg", 0, true);
 421     }
 422 }
 423
 424 bool FGAIBallistic::getHtAGL(){
 425
 426     if (globals->get_scenery()->get_elevation_m(pos.getLatitudeDeg(), pos.getLongitudeDeg(),
 427         10000.0, _elevation_m, &_material)){
 428             _ht_agl_ft = pos.getElevationFt() - _elevation_m * SG_METER_TO_FEET;
 429             if (_material) {
 430                 const vector<string>& names = _material->get_names();
 431
 432                 _solid = _material->get_solid();
 433                 _load_resistance = _material->get_load_resistance();
 434                 _frictionFactor =_material->get_friction_factor();
 435                 if (!names.empty())
 436                     props->setStringValue("material/name", names[0].c_str());
 437                 else
 438                     props->setStringValue("material/name", "");
 439                 /*cout << "material " << mat_name
 440                 << " solid " << _solid
 441                 << " load " << _load_resistance
 442                 << " frictionFactor " << frictionFactor
 443                 << endl;*/
 444             }
 445             return true;
 446     } else {
 447         return false;
 448     }
 449
 450 }
 451
 452 double FGAIBallistic::getRecip(double az){
 453     // calculate the reciprocal of the input azimuth
 454     if(az - 180 < 0){
 455         return az + 180;
 456     } else {
 457         return az - 180;
 458     }
 459 }
 460
 461 void FGAIBallistic::setPch(double e, double dt, double coeff){
 462     double c = dt / (coeff + dt);
 463     pitch = (e * c) + (pitch * (1 - c));
 464 }
 465
 466 void FGAIBallistic::setBnk(double r, double dt, double coeff){
 467     double c = dt / (coeff + dt);
 468     roll = (r * c) + (roll * (1 - c));
 469 }
 470
 471 void FGAIBallistic::setHt(double h, double dt, double coeff){
 472     double c = dt / (coeff + dt);
 473     _height = (h * c) + (_height * (1 - c));
 474 }
 475
 476 void FGAIBallistic::setHdg(double az, double dt, double coeff){
 477     double recip = getRecip(hdg);
 478     double c = dt / (coeff + dt);
 479     //we need to ensure that we turn the short way to the new hdg
 480     if (az < recip && az < hdg && hdg > 180) {
 481         hdg = ((az + 360) * c) + (hdg * (1 - c));
 482     } else if (az > recip && az > hdg && hdg <= 180){
 483         hdg = ((az - 360) * c) + (hdg * (1 - c));
 484     } else {
 485         hdg = (az * c) + (hdg * (1 - c));
 486     }
 487     }
 488
 489 double  FGAIBallistic::getTgtXOffset() const {
 490     return _tgt_x_offset;
 491 }
 492
 493 double  FGAIBallistic::getTgtYOffset() const {
 494     return _tgt_y_offset;
 495 }
 496
 497 double  FGAIBallistic::getTgtZOffset() const {
 498     return _tgt_z_offset;
 499 }
 500
 501 void FGAIBallistic::setTgtXOffset(double x){
 502     _tgt_x_offset = x;
 503 }
 504
 505 void FGAIBallistic::setTgtYOffset(double y){
 506     _tgt_y_offset = y;
 507 }
 508
 509 void FGAIBallistic::setTgtZOffset(double z){
 510     _tgt_z_offset = z;
 511 }
 512
 513 void FGAIBallistic::slaveToAC(double dt){
 514
 515     setHitchPos();
 516     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 517     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 518     pos.setElevationFt(hitchpos.getElevationFt());
 519     setHeading(manager->get_user_heading());
 520     setPitch(manager->get_user_pitch() + _pitch_offset);
 521     setBank(manager->get_user_roll() + _roll_offset);
 522     setSpeed(manager->get_user_speed());
 523     //update the mass (slugs)
 524     _mass = (_weight_lb + getContents()) / slugs_to_lbs;
 525
 526     /*cout <<"_mass "<<_mass <<" " << getContents()
 527     <<" " << getContents() / slugs_to_lbs << endl;*/
 528 }
 529
 530 void FGAIBallistic::Run(double dt) {
 531     _life_timer += dt;
 532
 533     // if life = -1 the object does not die
 534     if (_life_timer > life && life != -1)
 535         setDie(true);
 536
 537     //set the contents in the appropriate tank or other property in the parent to zero
 538     setContents(0);
 539
 540     //randomise Cd by +- 5%
 541     if (_random)
 542         _Cd = _Cd * 0.95 + (0.05 * sg_random());
 543
 544     // Adjust Cd by Mach number. The equations are based on curves
 545     // for a conventional shell/bullet (no boat-tail).
 546     double Cdm;
 547
 548     if (Mach < 0.7)
 549         Cdm = 0.0125 * Mach + _Cd;
 550     else if (Mach < 1.2 )
 551         Cdm = 0.3742 * pow(Mach, 2) - 0.252 * Mach + 0.0021 + _Cd;
 552     else
 553         Cdm = 0.2965 * pow(Mach, -1.1506) + _Cd;
 554
 555     //cout << "Mach " << Mach << " Cdm " << Cdm << "// ballistic speed kts "<< speed <<  endl;
 556
 557     // drag = Cd * 0.5 * rho * speed * speed * drag_area;
 558     // rho is adjusted for altitude in void FGAIBase::update,
 559     // using Standard Atmosphere (sealevel temperature 15C)
 560     // acceleration = drag/mass;
 561     // adjust speed by drag
 562     speed -= (Cdm * 0.5 * rho * speed * speed * _drag_area/_mass) * dt;
 563
 564     // don't let speed become negative
 565     if ( speed < 0.0 )
 566         speed = 0.0;
 567
 568     double speed_fps = speed * SG_KT_TO_FPS;
 569     //double hs;
 570
 571     // calculate vertical and horizontal speed components
 572     if (speed == 0.0) {
 573         hs = vs = 0.0;
 574     } else {
 575         vs = sin( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 576         hs = cos( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 577     }
 578
 579     //resolve horizontal speed into north and east components:
 580     double speed_north_fps = cos(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 581     double speed_east_fps = sin(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 582
 583     // convert horizontal speed (fps) to degrees per second
 584     double speed_north_deg_sec = speed_north_fps / ft_per_deg_lat;
 585     double speed_east_deg_sec  = speed_east_fps / ft_per_deg_lon;
 586
 587     // if wind not required, set to zero
 588     if (!_wind) {
 589         _wind_from_north = 0;
 590         _wind_from_east = 0;
 591     } else {
 592         _wind_from_north = manager->get_wind_from_north();
 593         _wind_from_east = manager->get_wind_from_east();
 594     }
 595
 596     //calculate velocity due to external force
 597     double force_speed_north_deg_sec = 0;
 598     double force_speed_east_deg_sec = 0;
 599     double vs_force_fps = 0;
 600     double hs_force_fps = 0;
 601     double v_force_acc_fpss = 0;
 602     double force_speed_north_fps = 0;
 603     double force_speed_east_fps = 0;
 604     double h_force_lbs = 0;
 605     double normal_force_lbs = 0;
 606     double normal_force_fpss = 0;
 607     double static_friction_force_lbs = 0;
 608     double dynamic_friction_force_lbs = 0;
 609     double friction_force_speed_north_fps = 0;
 610     double friction_force_speed_east_fps = 0;
 611     double friction_force_speed_north_deg_sec = 0;
 612     double friction_force_speed_east_deg_sec = 0;
 613     double force_elevation_deg = 0;
 614
 615     if (_external_force) {
 616         SGPropertyNode *n = fgGetNode(_force_path.c_str(), true);
 617         double force_lbs            = n->getChild("force-lb", 0, true)->getDoubleValue();
 618         force_elevation_deg         = n->getChild("force-elevation-deg", 0, true)->getDoubleValue();
 619         double force_azimuth_deg    = n->getChild("force-azimuth-deg", 0, true)->getDoubleValue();
 620
 621         //resolve force into vertical and horizontal components:
 622         double v_force_lbs = force_lbs * sin( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 623         h_force_lbs = force_lbs * cos( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 624
 625         //ground interaction
 626
 627         if (getHtAGL()){
 628             double deadzone = 0.1;
 629
 630             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 631                 normal_force_lbs = (_mass * slugs_to_lbs) - v_force_lbs;
 632
 633                 if ( normal_force_lbs < 0 )
 634                     normal_force_lbs = 0;
 635
 636                 pos.setElevationFt(0 + _ground_offset);
 637                 if (vs < 0)
 638                     vs = -vs * 0.5;
 639
 640                 // calculate friction
 641                 // we assume a static Coefficient of Friction (mu) of 0.62 (wood on concrete)
 642                 double mu = 0.62;
 643
 644                 static_friction_force_lbs = mu * normal_force_lbs * _frictionFactor;
 645
 646                 //adjust horizontal force. We assume that a speed of <= 5 fps is static
 647                 if (h_force_lbs <= static_friction_force_lbs && hs <= 5){
 648                     h_force_lbs = hs = 0;
 649                     speed_north_fps = speed_east_fps = 0;
 650                 } else
 651                     dynamic_friction_force_lbs = (static_friction_force_lbs * 0.95);
 652
 653                 //ignore wind when on the ground for now
 654                 //TODO fix this
 655                 _wind_from_north = 0;
 656                 _wind_from_east = 0;
 657
 658             }
 659
 660         }
 661
 662         //acceleration = (force(lbsf)/mass(slugs))
 663         v_force_acc_fpss = v_force_lbs/_mass;
 664         normal_force_fpss = normal_force_lbs/_mass;
 665         double h_force_acc_fpss = h_force_lbs/_mass;
 666         double dynamic_friction_acc_fpss = dynamic_friction_force_lbs/_mass;
 667
 668         // velocity = acceleration * dt
 669         hs_force_fps = h_force_acc_fpss * dt;
 670         double friction_force_fps = dynamic_friction_acc_fpss * dt;
 671
 672         //resolve horizontal speeds into north and east components:
 673         force_speed_north_fps   = cos(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 674         force_speed_east_fps    = sin(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 675
 676         friction_force_speed_north_fps = cos(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 677         friction_force_speed_east_fps  = sin(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 678
 679         // convert horizontal speed (fps) to degrees per second
 680         force_speed_north_deg_sec = force_speed_north_fps / ft_per_deg_lat;
 681         force_speed_east_deg_sec  = force_speed_east_fps / ft_per_deg_lon;
 682
 683         friction_force_speed_north_deg_sec = friction_force_speed_north_fps / ft_per_deg_lat;
 684         friction_force_speed_east_deg_sec  = friction_force_speed_east_fps / ft_per_deg_lon;
 685     }
 686
 687     // convert wind speed (fps) to degrees lat/lon per second
 688     double wind_speed_from_north_deg_sec = _wind_from_north / ft_per_deg_lat;
 689     double wind_speed_from_east_deg_sec  = _wind_from_east / ft_per_deg_lon;
 690
 691     //recombine the horizontal velocity components
 692     hs = sqrt(((speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps)
 693         * (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 694         + ((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)
 695         * (speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)));
 696
 697     if (hs <= 0.00001)
 698         hs = 0;
 699
 700     // adjust vertical speed for acceleration of gravity, buoyancy, and vertical force
 701     vs -= (_gravity - _buoyancy - v_force_acc_fpss - normal_force_fpss) * dt;
 702
 703     if (vs <= 0.00001 && vs >= -0.00001)
 704         vs = 0;
 705
 706     // set new position
 707     if(_slave_load_to_ac) {
 708         setHitchPos();
 709         pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 710         pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 711         pos.setElevationFt(hitchpos.getElevationFt());
 712
 713         if (getHtAGL()){
 714             double deadzone = 0.1;
 715
 716             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 717                 pos.setElevationFt(0 + _ground_offset);
 718             } else {
 719                 pos.setElevationFt(hitchpos.getElevationFt() + _load_offset);
 720             }
 721
 722         }
 723     } else {
 724         pos.setLatitudeDeg( pos.getLatitudeDeg()
 725             + (speed_north_deg_sec - wind_speed_from_north_deg_sec
 726             + force_speed_north_deg_sec + friction_force_speed_north_deg_sec) * dt );
 727         pos.setLongitudeDeg( pos.getLongitudeDeg()
 728             + (speed_east_deg_sec - wind_speed_from_east_deg_sec
 729             + force_speed_east_deg_sec + friction_force_speed_east_deg_sec) * dt );
 730         pos.setElevationFt(pos.getElevationFt() + vs * dt);
 731     }
 732
 733     // recalculate total speed
 734     if ( vs == 0 && hs == 0)
 735         speed = 0;
 736     else
 737         speed = sqrt( vs * vs + hs * hs) / SG_KT_TO_FPS;
 738
 739     // recalculate elevation and azimuth (velocity vectors)
 740     _elevation = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
 741     _azimuth =  atan2((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps),
 742         (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 743         * SG_RADIANS_TO_DEGREES;
 744
 745     // rationalise azimuth
 746     if (_azimuth < 0)
 747         _azimuth += 360;
 748
 749     if (_aero_stabilised) { // we simulate rotational moment of inertia by using a filter
 750         const double coeff = 0.9;
 751
 752         // we assume a symetrical MI about the pitch and yaw axis
 753         setPch(_elevation, dt, coeff);
 754         setHdg(_azimuth, dt, coeff);
 755     } else if (_force_stabilised) { // we simulate rotational moment of inertia by using a filter
 756         const double coeff = 0.9;
 757         double ratio = h_force_lbs/(_mass * slugs_to_lbs);
 758
 759         if (ratio >  1) ratio =  1;
 760         if (ratio < -1) ratio = -1;
 761
 762         double force_pitch = acos(ratio) * SG_RADIANS_TO_DEGREES;
 763
 764         if (force_pitch <= force_elevation_deg)
 765             force_pitch = force_elevation_deg;
 766
 767         // we assume a symetrical MI about the pitch and yaw axis
 768         setPch(force_pitch,dt, coeff);
 769         setHdg(_azimuth, dt, coeff);
 770     }
 771
 772     //do impacts and collisions
 773     if (_report_impact && !_impact_reported)
 774         handle_impact();
 775
 776     if (_report_collision && !_collision_reported)
 777         handle_collision();
 778
 779     // set destruction flag if altitude less than sea level -1000
 780     if (altitude_ft < -1000.0 && life != -1)
 781         setDie(true);
 782
 783 }  // end Run
 784
 785 double FGAIBallistic::_getTime() const {
 786     return _life_timer;
 787 }
 788
 789 void FGAIBallistic::handle_impact() {
 790
 791     // try terrain intersection
 792     if(!getHtAGL())
 793         return;
 794
 795     if (_ht_agl_ft <= 0) {
 796         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: terrain impact");
 797         report_impact(_elevation_m);
 798         _impact_reported = true;
 799
 800         if (life == -1){
 801             invisible = true;
 802         } else if (_subID == 0)  // kill the AIObject if there is no subsubmodel
 803             setDie(true);
 804     }
 805 }
 806
 807 void FGAIBallistic::handle_collision()
 808 {
 809     const FGAIBase *object = manager->calcCollision(pos.getElevationFt(),
 810             pos.getLatitudeDeg(),pos.getLongitudeDeg(), _fuse_range);
 811
 812     if (object) {
 813         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: object hit");
 814         report_impact(pos.getElevationM(), object);
 815         _collision_reported = true;
 816     }
 817 }
 818
 819 void FGAIBallistic::report_impact(double elevation, const FGAIBase *object)
 820 {
 821     _impact_lat    = pos.getLatitudeDeg();
 822     _impact_lon    = pos.getLongitudeDeg();
 823     _impact_elev   = elevation;
 824     _impact_speed  = speed * SG_KT_TO_MPS;
 825     _impact_hdg    = hdg;
 826     _impact_pitch  = pitch;
 827     _impact_roll   = roll;
 828
 829     SGPropertyNode *n = props->getNode("impact", true);
 830     if (object)
 831         n->setStringValue("type", object->getTypeString());
 832     else
 833         n->setStringValue("type", "terrain");
 834
 835     n->setDoubleValue("longitude-deg", _impact_lon);
 836     n->setDoubleValue("latitude-deg", _impact_lat);
 837     n->setDoubleValue("elevation-m", _impact_elev);
 838     n->setDoubleValue("heading-deg", _impact_hdg);
 839     n->setDoubleValue("pitch-deg", _impact_pitch);
 840     n->setDoubleValue("roll-deg", _impact_roll);
 841     n->setDoubleValue("speed-mps", _impact_speed);
 842
 843     _impact_report_node->setStringValue(props->getPath());
 844 }
 845
 846 SGVec3d FGAIBallistic::getCartUserPos() const {
 847     SGVec3d cartUserPos = SGVec3d::fromGeod(userpos);
 848     return cartUserPos;
 849 }
 850
 851 SGVec3d FGAIBallistic::getCartHitchPos() const{
 852
 853     // convert geodetic positions to geocentered
 854     SGVec3d cartuserPos = getCartUserPos();
 855     SGVec3d cartPos = getCartPos();
 856
 857     // Transform to the right coordinate frame, configuration is done in
 858     // the x-forward, y-right, z-up coordinates (feet), computation
 859     // in the simulation usual body x-forward, y-right, z-down coordinates
 860     // (meters) )
 861     SGVec3d _off(_x_offset * SG_FEET_TO_METER,
 862         _y_offset * SG_FEET_TO_METER,
 863         -_z_offset * SG_FEET_TO_METER);
 864
 865     // Transform the user position to the horizontal local coordinate system.
 866     SGQuatd hlTrans = SGQuatd::fromLonLat(userpos);
 867
 868     // and postrotate the orientation of the user model wrt the horizontal
 869     // local frame
 870     hlTrans *= SGQuatd::fromYawPitchRollDeg(
 871         manager->get_user_heading(),
 872         manager->get_user_pitch(),
 873         manager->get_user_roll());
 874
 875     // The offset converted to the usual body fixed coordinate system
 876     // rotated to the earth-fixed coordinates axis
 877     SGVec3d off = hlTrans.backTransform(_off);
 878
 879     // Add the position offset of the user model to get the geocentered position
 880     SGVec3d offsetPos = cartuserPos + off;
 881
 882     return offsetPos;
 883 }
 884
 885 void FGAIBallistic::setHitchPos(){
 886     // convert the hitch geocentered position to geodetic
 887     SGVec3d carthitchPos = getCartHitchPos();
 888
 889     SGGeodesy::SGCartToGeod(carthitchPos, hitchpos);
 890 }
 891
 892 double FGAIBallistic::getDistanceLoadToHitch() const {
 893     //calculate the distance load to hitch
 894     SGVec3d carthitchPos = getCartHitchPos();
 895     SGVec3d cartPos = getCartPos();
 896
 897     SGVec3d diff = carthitchPos - cartPos;
 898     double distance = norm(diff);
 899     return distance * SG_METER_TO_FEET;
 900 }
 901
 902 void FGAIBallistic::setHitchVelocity(double dt) {
 903     //calculate the distance from the previous hitch position
 904     SGVec3d carthitchPos = getCartHitchPos();
 905     SGVec3d diff = carthitchPos - _oldcarthitchPos;
 906
 907     double distance = norm(diff);
 908
 909     //calculate speed knots
 910     speed = (distance/dt) * SG_MPS_TO_KT;
 911
 912     //now calulate the angle between the old and current hitch positions (degrees)
 913     double angle = 0;
 914     double daltM = hitchpos.getElevationM() - oldhitchpos.getElevationM();
 915
 916     if (fabs(distance) < SGLimits<float>::min()) {
 917         angle = 0;
 918     } else {
 919         double sAngle = daltM/distance;
 920         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 921         angle = SGMiscd::rad2deg(asin(sAngle));
 922     }
 923
 924     _elevation = angle;
 925
 926     //calculate the bearing of the new hitch position from the old
 927     double az1, az2, dist;
 928
 929     geo_inverse_wgs_84(oldhitchpos, hitchpos, &az1, &az2, &dist);
 930
 931     _azimuth = az1;
 932
 933     // and finally store the new values
 934     _oldcarthitchPos = carthitchPos;
 935     oldhitchpos = hitchpos;
 936 }
 937
 938 double FGAIBallistic::getElevLoadToHitch() const {
 939     // now the angle, positive angles are upwards
 940     double distance = getDistanceLoadToHitch() * SG_FEET_TO_METER;
 941     double angle = 0;
 942     double daltM = hitchpos.getElevationM() - pos.getElevationM();
 943
 944     if (fabs(distance) < SGLimits<float>::min()) {
 945         angle = 0;
 946     } else {
 947         double sAngle = daltM/distance;
 948         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 949         angle = SGMiscd::rad2deg(asin(sAngle));
 950     }
 951
 952     return angle;
 953 }
 954
 955 double FGAIBallistic::getBearingLoadToHitch() const {
 956     //calculate the bearing and range of the second pos from the first
 957     double az1, az2, distance;
 958
 959     geo_inverse_wgs_84(pos, hitchpos, &az1, &az2, &distance);
 960
 961     return az1;
 962 }
 963
 964 double FGAIBallistic::getRelBrgHitchToUser() const {
 965     //calculate the relative bearing
 966     double az1, az2, distance;
 967
 968     geo_inverse_wgs_84(hitchpos, userpos, &az1, &az2, &distance);
 969
 970     double rel_brg = az1 - hdg;
 971
 972     if (rel_brg > 180)
 973         rel_brg -= 360;
 974
 975     return rel_brg;
 976 }
 977
 978 double FGAIBallistic::getElevHitchToUser() const {
 979
 980     //calculate the distance from the user position
 981     SGVec3d carthitchPos = getCartHitchPos();
 982     SGVec3d cartuserPos = getCartUserPos();
 983
 984     SGVec3d diff = cartuserPos - carthitchPos;
 985
 986     double distance = norm(diff);
 987     double angle = 0;
 988
 989     double daltM = userpos.getElevationM() - hitchpos.getElevationM();
 990
 991     // now the angle, positive angles are upwards
 992     if (fabs(distance) < SGLimits<float>::min()) {
 993         angle = 0;
 994     } else {
 995         double sAngle = daltM/distance;
 996         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 997         angle = SGMiscd::rad2deg(asin(sAngle));
 998     }
 999
1000     return angle;
1001 }
1002
1003 void FGAIBallistic::setTgtOffsets(double dt, double coeff){
1004     double c = dt / (coeff + dt);
1005
1006     _x_offset = (_tgt_x_offset * c) + (_x_offset * (1 - c));
1007     _y_offset = (_tgt_y_offset * c) + (_y_offset * (1 - c));
1008     _z_offset = (_tgt_z_offset * c) + (_z_offset * (1 - c));
1009 }
1010
1011 void FGAIBallistic::formateToAC(double dt){
1012
1013     setTgtOffsets(dt, 25);
1014     setHitchPos();
1015     setHitchVelocity(dt);
1016
1017     // elapsed time has a random initialisation so that each
1018     // wingman moves differently
1019     _elapsed_time += dt;
1020
1021     // we derive a sine based factor to give us smoothly
1022     // varying error between -1 and 1
1023     double factor  = sin(SGMiscd::deg2rad(_elapsed_time * 10));
1024     double r_angle = 5 * factor;
1025     double p_angle = 2.5 * factor;
1026     double h_angle = 5 * factor;
1027     double h_feet  = 3 * factor;
1028
1029     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
1030     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
1031
1032     if (getHtAGL()){
1033
1034         if(_ht_agl_ft <= 10) {
1035             _height = userpos.getElevationFt();
1036         } else if (_ht_agl_ft > 10 && _ht_agl_ft <= 150 ) {
1037             setHt(userpos.getElevationFt(), dt, 1.0);
1038         } else if (_ht_agl_ft > 150 && _ht_agl_ft <= 250) {
1039             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.75);
1040         } else
1041             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.5);
1042
1043         pos.setElevationFt(_height);
1044     }
1045
1046     // these calculations are unreliable at slow speeds
1047     if(speed >= 10) {
1048         setHdg(_azimuth + h_angle, dt, 0.9);
1049         setPch(_elevation + p_angle + _pitch_offset, dt, 0.9);
1050
1051         if (roll <= 115 && roll >= -115)
1052             setBnk(manager->get_user_roll() + r_angle + _roll_offset, dt, 0.5);
1053         else
1054             roll = manager->get_user_roll() + r_angle + _roll_offset;
1055
1056     } else {
1057         setHdg(manager->get_user_heading(), dt, 0.9);
1058         setPch(manager->get_user_pitch() + _pitch_offset, dt, 0.9);
1059         setBnk(manager->get_user_roll() + _roll_offset, dt, 0.9);
1060     }
1061
1062     setSpeed(speed);
1063 }
1064 // end AIBallistic