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 "AIModelData.hxx"
  33 #include "AIBallistic.hxx"
  34
  35 #include <Main/util.hxx>
  36
  37 const double FGAIBallistic::slugs_to_kgs = 14.5939029372;
  38 const double FGAIBallistic::slugs_to_lbs = 32.1740485564;
  39
  40 using namespace simgear;
  41
  42 FGAIBallistic::FGAIBallistic(object_type ot) :
  43 FGAIBase(ot),
  44     _elevation(0),
  45     _aero_stabilised(false),
  46     _drag_area(0.007),
  47     _life_timer(0.0),
  48 _gravity(32.1740485564),
  49     _buoyancy(0),
  50     _random(false),
  51     _ht_agl_ft(0),
  52     _load_resistance(0),
  53     _solid(false),
  54     _report_collision(false),
  55     _report_impact(false),
  56 _wind(true),
  57     _impact_report_node(fgGetNode("/ai/models/model-impact", true)),
  58 _external_force(false),
  59 _slave_to_ac(false),
  60 _slave_load_to_ac(false),
  61 _formate_to_ac(false),
  62 _contents_lb(0),
  63 _mass(0),
  64 _height(0),
  65 _old_height(0)
  66
  67 {
  68     no_roll = false;
  69 }
  70
  71 FGAIBallistic::~FGAIBallistic() {
  72 }
  73
  74 void FGAIBallistic::readFromScenario(SGPropertyNode* scFileNode) {
  75     if (!scFileNode){
  76         return;
  77     }
  78
  79     FGAIBase::readFromScenario(scFileNode);
  80
  81     //setPath(scFileNode->getStringValue("model", "Models/Geometry/rocket.ac"));
  82     setAzimuth(scFileNode->getDoubleValue("azimuth", 0.0));
  83     setElevation(scFileNode->getDoubleValue("elevation", 0));
  84     setDragArea(scFileNode->getDoubleValue("eda", 0.007));
  85     setLife(scFileNode->getDoubleValue("life", 900.0));
  86     setBuoyancy(scFileNode->getDoubleValue("buoyancy", 0));
  87     setWind_from_east(scFileNode->getDoubleValue("wind_from_east", 0));
  88     setWind_from_north(scFileNode->getDoubleValue("wind_from_north", 0));
  89     setWind(scFileNode->getBoolValue("wind", false));
  90     setRoll(scFileNode->getDoubleValue("roll", 0.0));
  91     setCd(scFileNode->getDoubleValue("cd", 0.029));
  92     //setMass(scFileNode->getDoubleValue("mass", 0.007));
  93     setWeight(scFileNode->getDoubleValue("weight", 0.25));
  94     setStabilisation(scFileNode->getBoolValue("aero_stabilized", false));
  95     setNoRoll(scFileNode->getBoolValue("no-roll", false));
  96     setRandom(scFileNode->getBoolValue("random", false));
  97     setImpact(scFileNode->getBoolValue("impact", false));
  98     setImpactReportNode(scFileNode->getStringValue("impact-reports"));
  99     setName(scFileNode->getStringValue("name", "Rocket"));
 100     setFuseRange(scFileNode->getDoubleValue("fuse-range", 0.0));
 101     setSMPath(scFileNode->getStringValue("submodel-path", ""));
 102     setSubID(scFileNode->getIntValue("SubID", 0));
 103     setExternalForce(scFileNode->getBoolValue("external-force", false));
 104     setForcePath(scFileNode->getStringValue("force-path", ""));
 105     setForceStabilisation(scFileNode->getBoolValue("force_stabilized", false));
 106     setXoffset(scFileNode->getDoubleValue("x-offset", 0.0));
 107     setYoffset(scFileNode->getDoubleValue("y-offset", 0.0));
 108     setZoffset(scFileNode->getDoubleValue("z-offset", 0.0));
 109     setPitchoffset(scFileNode->getDoubleValue("pitch-offset", 0.0));
 110     setRolloffset(scFileNode->getDoubleValue("roll-offset", 0.0));
 111     setYawoffset(scFileNode->getDoubleValue("yaw-offset", 0.0));
 112     setGroundOffset(scFileNode->getDoubleValue("ground-offset", 0.0));
 113     setLoadOffset(scFileNode->getDoubleValue("load-offset", 0.0));
 114     setSlaved(scFileNode->getBoolValue("slaved", false));
 115     setSlavedLoad(scFileNode->getBoolValue("slaved-load", false));
 116     setContentsNode(scFileNode->getStringValue("contents"));
 117     setRandom(scFileNode->getBoolValue("random", false));
 118 }
 119
 120 osg::Node* FGAIBallistic::load3DModel(const string &path, SGPropertyNode *prop_root)
 121 {
 122   model = SGModelLib::loadModel(path, prop_root, new FGAIModelData(this, prop_root));
 123   return model.get();
 124 }
 125
 126 bool FGAIBallistic::init(bool search_in_AI_path) {
 127     FGAIBase::init(search_in_AI_path);
 128
 129     _impact_reported = false;
 130     _collision_reported = false;
 131     invisible = false;
 132
 133     _elapsed_time += (sg_random() * 100);
 134
 135     props->setStringValue("material/name", "");
 136     props->setStringValue("name", _name.c_str());
 137     props->setStringValue("submodels/path", _submodel.c_str());
 138
 139     // start with high value so that animations don't trigger yet
 140     _ht_agl_ft = 1e10;
 141     hdg = _azimuth;
 142     pitch = _elevation;
 143     roll = _rotation;
 144
 145     Transform();
 146
 147     return true;
 148 }
 149
 150 void FGAIBallistic::bind() {
 151     //    FGAIBase::bind();
 152
 153     props->tie("sim/time/elapsed-sec",
 154         SGRawValueMethods<FGAIBallistic,double>(*this,
 155         &FGAIBallistic::_getTime));
 156     props->tie("mass-slug",
 157         SGRawValueMethods<FGAIBallistic,double>(*this,
 158         &FGAIBallistic::getMass));
 159     props->tie("material/load-resistance",
 160                 SGRawValuePointer<double>(&_load_resistance));
 161     props->tie("material/solid",
 162                 SGRawValuePointer<bool>(&_solid));
 163     props->tie("altitude-agl-ft",
 164                 SGRawValuePointer<double>(&_ht_agl_ft));
 165     props->tie("controls/slave-to-ac",
 166         SGRawValueMethods<FGAIBallistic,bool>
 167         (*this, &FGAIBallistic::getSlaved, &FGAIBallistic::setSlaved));
 168     props->tie("controls/invisible",
 169         SGRawValuePointer<bool>(&invisible));
 170
 171     if(_external_force){
 172         props->tie("controls/force_stabilized",
 173             SGRawValuePointer<bool>(&_force_stabilised));
 174         props->tie("position/global-x",
 175             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosX, 0));
 176         props->tie("position/global-y",
 177             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosY, 0));
 178         props->tie("position/global-z",
 179             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosZ, 0));
 180         props->tie("velocities/vertical-speed-fps",
 181             SGRawValuePointer<double>(&vs));
 182         props->tie("velocities/true-airspeed-kt",
 183             SGRawValuePointer<double>(&speed));
 184         props->tie("velocities/horizontal-speed-fps",
 185             SGRawValuePointer<double>(&hs));
 186         props->tie("position/altitude-ft",
 187             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getAltitude, &FGAIBase::_setAltitude));
 188         props->tie("position/latitude-deg",
 189             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLatitude, &FGAIBase::_setLatitude));
 190         props->tie("position/longitude-deg",
 191             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLongitude, &FGAIBase::_setLongitude));
 192         props->tie("orientation/hdg-deg",
 193             SGRawValuePointer<double>(&hdg));
 194         props->tie("orientation/pitch-deg",
 195             SGRawValuePointer<double>(&pitch));
 196         props->tie("orientation/roll-deg",
 197             SGRawValuePointer<double>(&roll));
 198         props->tie("controls/slave-load-to-ac",
 199             SGRawValueMethods<FGAIBallistic,bool>
 200             (*this, &FGAIBallistic::getSlavedLoad, &FGAIBallistic::setSlavedLoad));
 201         props->tie("position/load-offset",
 202             SGRawValueMethods<FGAIBallistic,double>
 203             (*this, &FGAIBallistic::getLoadOffset, &FGAIBallistic::setLoadOffset));
 204         props->tie("load/distance-to-hitch-ft",
 205             SGRawValueMethods<FGAIBallistic,double>
 206             (*this, &FGAIBallistic::getDistanceLoadToHitch));
 207         props->tie("load/elevation-to-hitch-deg",
 208             SGRawValueMethods<FGAIBallistic,double>
 209             (*this, &FGAIBallistic::getElevLoadToHitch));
 210         props->tie("load/bearing-to-hitch-deg",
 211             SGRawValueMethods<FGAIBallistic,double>
 212             (*this, &FGAIBallistic::getBearingLoadToHitch));
 213     }
 214
 215 }
 216
 217 void FGAIBallistic::unbind() {
 218     //    FGAIBase::unbind();
 219
 220     props->untie("sim/time/elapsed-sec");
 221     props->untie("mass-slug");
 222     props->untie("material/load-resistance");
 223     props->untie("material/solid");
 224     props->untie("altitude-agl-ft");
 225     props->untie("controls/slave-to-ac");
 226     props->untie("controls/invisible");
 227
 228     if(_external_force){
 229         props->untie("position/global-y");
 230         props->untie("position/global-x");
 231         props->untie("position/global-z");
 232         props->untie("velocities/vertical-speed-fps");
 233         props->untie("velocities/true-airspeed-kt");
 234         props->untie("velocities/horizontal-speed-fps");
 235         props->untie("position/altitude-ft");
 236         props->untie("position/latitude-deg");
 237         props->untie("position/longitude-deg");
 238         props->untie("position/ht-agl-ft");
 239         props->untie("orientation/hdg-deg");
 240         props->untie("orientation/pitch-deg");
 241         props->untie("orientation/roll-deg");
 242         props->untie("controls/force_stabilized");
 243         props->untie("position/load-offset");
 244         props->untie("load/distance-to-hitch-ft");
 245         props->untie("load/elevation-to-hitch-deg");
 246         props->untie("load/bearing-to-hitch-deg");
 247     }
 248 }
 249
 250 void FGAIBallistic::update(double dt) {
 251     FGAIBase::update(dt);
 252     _setUserPos();
 253
 254     if (_slave_to_ac){
 255         slaveToAC(dt);
 256         Transform();
 257         setHitchVelocity(dt);
 258     } else if (_formate_to_ac){
 259         formateToAC(dt);
 260         Transform();
 261         setHitchVelocity(dt);
 262     } else if (!invisible){
 263     Run(dt);
 264     Transform();
 265 }
 266
 267 }
 268
 269 void FGAIBallistic::setAzimuth(double az) {
 270     hdg = _azimuth = az;
 271 }
 272
 273 void FGAIBallistic::setElevation(double el) {
 274     pitch = _elevation = el;
 275 }
 276
 277 void FGAIBallistic::setRoll(double rl) {
 278     roll = _rotation = rl;
 279 }
 280
 281 void FGAIBallistic::setStabilisation(bool val) {
 282     _aero_stabilised = val;
 283 }
 284
 285 void FGAIBallistic::setForceStabilisation(bool val) {
 286     _force_stabilised = val;
 287 }
 288
 289 void FGAIBallistic::setNoRoll(bool nr) {
 290     no_roll = nr;
 291 }
 292
 293 void FGAIBallistic::setDragArea(double a) {
 294     _drag_area = a;
 295 }
 296
 297 void FGAIBallistic::setLife(double seconds) {
 298     life = seconds;
 299 }
 300
 301 void FGAIBallistic::setBuoyancy(double fpss) {
 302     _buoyancy = fpss;
 303 }
 304
 305 void FGAIBallistic::setWind_from_east(double fps) {
 306     _wind_from_east = fps;
 307 }
 308
 309 void FGAIBallistic::setWind_from_north(double fps) {
 310     _wind_from_north = fps;
 311 }
 312
 313 void FGAIBallistic::setWind(bool val) {
 314     _wind = val;
 315 }
 316
 317 void FGAIBallistic::setCd(double c) {
 318     _Cd = c;
 319 }
 320
 321 void FGAIBallistic::setMass(double m) {
 322     _mass = m;
 323 }
 324
 325 void FGAIBallistic::setWeight(double w) {
 326     _weight_lb = w;
 327 }
 328 void FGAIBallistic::setRandom(bool r) {
 329     _random = r;
 330 }
 331
 332 void FGAIBallistic::setImpact(bool i) {
 333     _report_impact = i;
 334 }
 335
 336 void FGAIBallistic::setCollision(bool c) {
 337     _report_collision = c;
 338 }
 339
 340 void FGAIBallistic::setExternalForce(bool f) {
 341     _external_force = f;
 342 }
 343
 344 void FGAIBallistic::setImpactReportNode(const string& path) {
 345
 346     if (!path.empty())
 347         _impact_report_node = fgGetNode(path.c_str(), true);
 348 }
 349
 350 void FGAIBallistic::setName(const string& n) {
 351     _name = n;
 352 }
 353
 354 void FGAIBallistic::setSMPath(const string& s) {
 355     _submodel = s;
 356 }
 357
 358 void FGAIBallistic::setFuseRange(double f) {
 359     _fuse_range = f;
 360 }
 361
 362 void FGAIBallistic::setSubID(int i) {
 363     _subID = i;
 364 }
 365
 366 void FGAIBallistic::setSubmodel(const string& s) {
 367     _submodel = s;
 368 }
 369
 370 void FGAIBallistic::setGroundOffset(double g) {
 371     _ground_offset = g;
 372 }
 373
 374 void FGAIBallistic::setLoadOffset(double l) {
 375     _load_offset = l;
 376 }
 377
 378 double FGAIBallistic::getLoadOffset() const {
 379     return _load_offset;
 380 }
 381
 382 void FGAIBallistic::setSlaved(bool s) {
 383     _slave_to_ac = s;
 384 }
 385
 386 void FGAIBallistic::setFormate(bool f) {
 387     _formate_to_ac = f;
 388 }
 389
 390 void FGAIBallistic::setContentsNode(const string& path) {
 391     if (!path.empty()) {
 392         _contents_node = fgGetNode(path.c_str(), true);
 393     }
 394 }
 395
 396 bool FGAIBallistic::getSlaved() const {
 397     return _slave_to_ac;
 398 }
 399
 400 double FGAIBallistic::getMass() const {
 401     return _mass;
 402 }
 403
 404 double FGAIBallistic::getContents() {
 405     if(_contents_node)
 406         _contents_lb = _contents_node->getChild("level-lbs",0,1)->getDoubleValue();
 407     return _contents_lb;
 408 }
 409
 410 void FGAIBallistic::setContents(double c) {
 411     if(_contents_node)
 412         _contents_lb = _contents_node->getChild("level-gal_us",0,1)->setDoubleValue(c);
 413 }
 414
 415 void FGAIBallistic::setSlavedLoad(bool l) {
 416     _slave_load_to_ac = l;
 417 }
 418
 419 bool FGAIBallistic::getSlavedLoad() const {
 420     return _slave_load_to_ac;
 421 }
 422
 423 void FGAIBallistic::setForcePath(const string& p) {
 424     _force_path = p;
 425     if (!_force_path.empty()) {
 426         SGPropertyNode *fnode = fgGetNode(_force_path.c_str(), 0, true );
 427         _force_node = fnode->getChild("force-lb", 0, true);
 428         _force_azimuth_node = fnode->getChild("force-azimuth-deg", 0, true);
 429         _force_elevation_node = fnode->getChild("force-elevation-deg", 0, true);
 430     }
 431 }
 432
 433 bool FGAIBallistic::getHtAGL(){
 434
 435     if (globals->get_scenery()->get_elevation_m(pos.getLatitudeDeg(), pos.getLongitudeDeg(),
 436         10000.0, _elevation_m, &_material)){
 437             _ht_agl_ft = pos.getElevationFt() - _elevation_m * SG_METER_TO_FEET;
 438             if (_material) {
 439                 const vector<string>& names = _material->get_names();
 440
 441                 _solid = _material->get_solid();
 442                 _load_resistance = _material->get_load_resistance();
 443                 _frictionFactor =_material->get_friction_factor();
 444                 if (!names.empty())
 445                     props->setStringValue("material/name", names[0].c_str());
 446                 else
 447                     props->setStringValue("material/name", "");
 448                 /*cout << "material " << mat_name
 449                 << " solid " << _solid
 450                 << " load " << _load_resistance
 451                 << " frictionFactor " << frictionFactor
 452                 << endl;*/
 453             }
 454             return true;
 455     } else {
 456         return false;
 457     }
 458
 459 }
 460
 461 double FGAIBallistic::getRecip(double az){
 462     // calculate the reciprocal of the input azimuth
 463     if(az - 180 < 0){
 464         return az + 180;
 465     } else {
 466         return az - 180;
 467     }
 468 }
 469
 470 void FGAIBallistic::setPch(double e, double dt, double coeff){
 471     double c = dt / (coeff + dt);
 472     pitch = (e * c) + (pitch * (1 - c));
 473 }
 474
 475 void FGAIBallistic::setBnk(double r, double dt, double coeff){
 476     double c = dt / (coeff + dt);
 477     roll = (r * c) + (roll * (1 - c));
 478 }
 479
 480 void FGAIBallistic::setHt(double h, double dt, double coeff){
 481     double c = dt / (coeff + dt);
 482     _height = (h * c) + (_height * (1 - c));
 483 }
 484
 485 void FGAIBallistic::setHdg(double az, double dt, double coeff){
 486     double recip = getRecip(hdg);
 487     double c = dt / (coeff + dt);
 488     //we need to ensure that we turn the short way to the new hdg
 489     if (az < recip && az < hdg && hdg > 180) {
 490         hdg = ((az + 360) * c) + (hdg * (1 - c));
 491     } else if (az > recip && az > hdg && hdg <= 180){
 492         hdg = ((az - 360) * c) + (hdg * (1 - c));
 493     } else {
 494         hdg = (az * c) + (hdg * (1 - c));
 495     }
 496     }
 497
 498 double  FGAIBallistic::getTgtXOffset() const {
 499     return _tgt_x_offset;
 500 }
 501
 502 double  FGAIBallistic::getTgtYOffset() const {
 503     return _tgt_y_offset;
 504 }
 505
 506 double  FGAIBallistic::getTgtZOffset() const {
 507     return _tgt_z_offset;
 508 }
 509
 510 void FGAIBallistic::setTgtXOffset(double x){
 511     _tgt_x_offset = x;
 512 }
 513
 514 void FGAIBallistic::setTgtYOffset(double y){
 515     _tgt_y_offset = y;
 516 }
 517
 518 void FGAIBallistic::setTgtZOffset(double z){
 519     _tgt_z_offset = z;
 520 }
 521
 522 void FGAIBallistic::slaveToAC(double dt){
 523
 524     setHitchPos();
 525     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 526     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 527     pos.setElevationFt(hitchpos.getElevationFt());
 528     setHeading(manager->get_user_heading());
 529     setPitch(manager->get_user_pitch() + _pitch_offset);
 530     setBank(manager->get_user_roll() + _roll_offset);
 531     setSpeed(manager->get_user_speed());
 532     //update the mass (slugs)
 533     _mass = (_weight_lb + getContents()) / slugs_to_lbs;
 534
 535     /*cout <<"_mass "<<_mass <<" " << getContents()
 536     <<" " << getContents() / slugs_to_lbs << endl;*/
 537 }
 538
 539 void FGAIBallistic::Run(double dt) {
 540     _life_timer += dt;
 541
 542     // if life = -1 the object does not die
 543     if (_life_timer > life && life != -1)
 544         setDie(true);
 545
 546     //set the contents in the appropriate tank or other property in the parent to zero
 547     setContents(0);
 548
 549     //randomise Cd by +- 5%
 550     if (_random)
 551         _Cd = _Cd * 0.95 + (0.05 * sg_random());
 552
 553     // Adjust Cd by Mach number. The equations are based on curves
 554     // for a conventional shell/bullet (no boat-tail).
 555     double Cdm;
 556
 557     if (Mach < 0.7)
 558         Cdm = 0.0125 * Mach + _Cd;
 559     else if (Mach < 1.2 )
 560         Cdm = 0.3742 * pow(Mach, 2) - 0.252 * Mach + 0.0021 + _Cd;
 561     else
 562         Cdm = 0.2965 * pow(Mach, -1.1506) + _Cd;
 563
 564     //cout << "Mach " << Mach << " Cdm " << Cdm << "// ballistic speed kts "<< speed <<  endl;
 565
 566     // drag = Cd * 0.5 * rho * speed * speed * drag_area;
 567     // rho is adjusted for altitude in void FGAIBase::update,
 568     // using Standard Atmosphere (sealevel temperature 15C)
 569     // acceleration = drag/mass;
 570     // adjust speed by drag
 571     speed -= (Cdm * 0.5 * rho * speed * speed * _drag_area/_mass) * dt;
 572
 573     // don't let speed become negative
 574     if ( speed < 0.0 )
 575         speed = 0.0;
 576
 577     double speed_fps = speed * SG_KT_TO_FPS;
 578     //double hs;
 579
 580     // calculate vertical and horizontal speed components
 581     if (speed == 0.0) {
 582         hs = vs = 0.0;
 583     } else {
 584         vs = sin( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 585         hs = cos( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 586     }
 587
 588     //resolve horizontal speed into north and east components:
 589     double speed_north_fps = cos(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 590     double speed_east_fps = sin(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 591
 592     // convert horizontal speed (fps) to degrees per second
 593     double speed_north_deg_sec = speed_north_fps / ft_per_deg_lat;
 594     double speed_east_deg_sec  = speed_east_fps / ft_per_deg_lon;
 595
 596     // if wind not required, set to zero
 597     if (!_wind) {
 598         _wind_from_north = 0;
 599         _wind_from_east = 0;
 600     } else {
 601         _wind_from_north = manager->get_wind_from_north();
 602         _wind_from_east = manager->get_wind_from_east();
 603     }
 604
 605     //calculate velocity due to external force
 606     double force_speed_north_deg_sec = 0;
 607     double force_speed_east_deg_sec = 0;
 608     double vs_force_fps = 0;
 609     double hs_force_fps = 0;
 610     double v_force_acc_fpss = 0;
 611     double force_speed_north_fps = 0;
 612     double force_speed_east_fps = 0;
 613     double h_force_lbs = 0;
 614     double normal_force_lbs = 0;
 615     double normal_force_fpss = 0;
 616     double static_friction_force_lbs = 0;
 617     double dynamic_friction_force_lbs = 0;
 618     double friction_force_speed_north_fps = 0;
 619     double friction_force_speed_east_fps = 0;
 620     double friction_force_speed_north_deg_sec = 0;
 621     double friction_force_speed_east_deg_sec = 0;
 622     double force_elevation_deg = 0;
 623
 624     if (_external_force) {
 625         SGPropertyNode *n = fgGetNode(_force_path.c_str(), true);
 626         double force_lbs            = n->getChild("force-lb", 0, true)->getDoubleValue();
 627         force_elevation_deg         = n->getChild("force-elevation-deg", 0, true)->getDoubleValue();
 628         double force_azimuth_deg    = n->getChild("force-azimuth-deg", 0, true)->getDoubleValue();
 629
 630         //resolve force into vertical and horizontal components:
 631         double v_force_lbs = force_lbs * sin( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 632         h_force_lbs = force_lbs * cos( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 633
 634         //ground interaction
 635
 636         if (getHtAGL()){
 637             double deadzone = 0.1;
 638
 639             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 640                 normal_force_lbs = (_mass * slugs_to_lbs) - v_force_lbs;
 641
 642                 if ( normal_force_lbs < 0 )
 643                     normal_force_lbs = 0;
 644
 645                 pos.setElevationFt(0 + _ground_offset);
 646                 if (vs < 0)
 647                     vs = -vs * 0.5;
 648
 649                 // calculate friction
 650                 // we assume a static Coefficient of Friction (mu) of 0.62 (wood on concrete)
 651                 double mu = 0.62;
 652
 653                 static_friction_force_lbs = mu * normal_force_lbs * _frictionFactor;
 654
 655                 //adjust horizontal force. We assume that a speed of <= 5 fps is static
 656                 if (h_force_lbs <= static_friction_force_lbs && hs <= 5){
 657                     h_force_lbs = hs = 0;
 658                     speed_north_fps = speed_east_fps = 0;
 659                 } else
 660                     dynamic_friction_force_lbs = (static_friction_force_lbs * 0.95);
 661
 662                 //ignore wind when on the ground for now
 663                 //TODO fix this
 664                 _wind_from_north = 0;
 665                 _wind_from_east = 0;
 666
 667             }
 668
 669         }
 670
 671         //acceleration = (force(lbsf)/mass(slugs))
 672         v_force_acc_fpss = v_force_lbs/_mass;
 673         normal_force_fpss = normal_force_lbs/_mass;
 674         double h_force_acc_fpss = h_force_lbs/_mass;
 675         double dynamic_friction_acc_fpss = dynamic_friction_force_lbs/_mass;
 676
 677         // velocity = acceleration * dt
 678         hs_force_fps = h_force_acc_fpss * dt;
 679         double friction_force_fps = dynamic_friction_acc_fpss * dt;
 680
 681         //resolve horizontal speeds into north and east components:
 682         force_speed_north_fps   = cos(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 683         force_speed_east_fps    = sin(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 684
 685         friction_force_speed_north_fps = cos(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 686         friction_force_speed_east_fps  = sin(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 687
 688         // convert horizontal speed (fps) to degrees per second
 689         force_speed_north_deg_sec = force_speed_north_fps / ft_per_deg_lat;
 690         force_speed_east_deg_sec  = force_speed_east_fps / ft_per_deg_lon;
 691
 692         friction_force_speed_north_deg_sec = friction_force_speed_north_fps / ft_per_deg_lat;
 693         friction_force_speed_east_deg_sec  = friction_force_speed_east_fps / ft_per_deg_lon;
 694     }
 695
 696     // convert wind speed (fps) to degrees lat/lon per second
 697     double wind_speed_from_north_deg_sec = _wind_from_north / ft_per_deg_lat;
 698     double wind_speed_from_east_deg_sec  = _wind_from_east / ft_per_deg_lon;
 699
 700     //recombine the horizontal velocity components
 701     hs = sqrt(((speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps)
 702         * (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 703         + ((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)
 704         * (speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)));
 705
 706     if (hs <= 0.00001)
 707         hs = 0;
 708
 709     // adjust vertical speed for acceleration of gravity, buoyancy, and vertical force
 710     vs -= (_gravity - _buoyancy - v_force_acc_fpss - normal_force_fpss) * dt;
 711
 712     if (vs <= 0.00001 && vs >= -0.00001)
 713         vs = 0;
 714
 715     // set new position
 716     if(_slave_load_to_ac) {
 717         setHitchPos();
 718         pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 719         pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 720         pos.setElevationFt(hitchpos.getElevationFt());
 721
 722         if (getHtAGL()){
 723             double deadzone = 0.1;
 724
 725             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 726                 pos.setElevationFt(0 + _ground_offset);
 727             } else {
 728                 pos.setElevationFt(hitchpos.getElevationFt() + _load_offset);
 729             }
 730
 731         }
 732     } else {
 733         pos.setLatitudeDeg( pos.getLatitudeDeg()
 734             + (speed_north_deg_sec - wind_speed_from_north_deg_sec
 735             + force_speed_north_deg_sec + friction_force_speed_north_deg_sec) * dt );
 736         pos.setLongitudeDeg( pos.getLongitudeDeg()
 737             + (speed_east_deg_sec - wind_speed_from_east_deg_sec
 738             + force_speed_east_deg_sec + friction_force_speed_east_deg_sec) * dt );
 739         pos.setElevationFt(pos.getElevationFt() + vs * dt);
 740     }
 741
 742     // recalculate total speed
 743     if ( vs == 0 && hs == 0)
 744         speed = 0;
 745     else
 746         speed = sqrt( vs * vs + hs * hs) / SG_KT_TO_FPS;
 747
 748     // recalculate elevation and azimuth (velocity vectors)
 749     _elevation = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
 750     _azimuth =  atan2((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps),
 751         (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 752         * SG_RADIANS_TO_DEGREES;
 753
 754     // rationalise azimuth
 755     if (_azimuth < 0)
 756         _azimuth += 360;
 757
 758     if (_aero_stabilised) { // we simulate rotational moment of inertia by using a filter
 759         const double coeff = 0.9;
 760
 761         // we assume a symetrical MI about the pitch and yaw axis
 762         setPch(_elevation, dt, coeff);
 763         setHdg(_azimuth, dt, coeff);
 764     } else if (_force_stabilised) { // we simulate rotational moment of inertia by using a filter
 765         const double coeff = 0.9;
 766         double ratio = h_force_lbs/(_mass * slugs_to_lbs);
 767
 768         if (ratio >  1) ratio =  1;
 769         if (ratio < -1) ratio = -1;
 770
 771         double force_pitch = acos(ratio) * SG_RADIANS_TO_DEGREES;
 772
 773         if (force_pitch <= force_elevation_deg)
 774             force_pitch = force_elevation_deg;
 775
 776         // we assume a symetrical MI about the pitch and yaw axis
 777         setPch(force_pitch,dt, coeff);
 778         setHdg(_azimuth, dt, coeff);
 779     }
 780
 781     //do impacts and collisions
 782     if (_report_impact && !_impact_reported)
 783         handle_impact();
 784
 785     if (_report_collision && !_collision_reported)
 786         handle_collision();
 787
 788     // set destruction flag if altitude less than sea level -1000
 789     if (altitude_ft < -1000.0 && life != -1)
 790         setDie(true);
 791
 792 }  // end Run
 793
 794 double FGAIBallistic::_getTime() const {
 795     return _life_timer;
 796 }
 797
 798 void FGAIBallistic::handle_impact() {
 799
 800     // try terrain intersection
 801     if(!getHtAGL())
 802         return;
 803
 804     if (_ht_agl_ft <= 0) {
 805         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: terrain impact");
 806         report_impact(_elevation_m);
 807         _impact_reported = true;
 808
 809         if (life == -1){
 810             invisible = true;
 811         } else if (_subID == 0)  // kill the AIObject if there is no subsubmodel
 812             setDie(true);
 813     }
 814 }
 815
 816 void FGAIBallistic::handle_collision()
 817 {
 818     const FGAIBase *object = manager->calcCollision(pos.getElevationFt(),
 819             pos.getLatitudeDeg(),pos.getLongitudeDeg(), _fuse_range);
 820
 821     if (object) {
 822         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: object hit");
 823         report_impact(pos.getElevationM(), object);
 824         _collision_reported = true;
 825     }
 826 }
 827
 828 void FGAIBallistic::report_impact(double elevation, const FGAIBase *object)
 829 {
 830     _impact_lat    = pos.getLatitudeDeg();
 831     _impact_lon    = pos.getLongitudeDeg();
 832     _impact_elev   = elevation;
 833     _impact_speed  = speed * SG_KT_TO_MPS;
 834     _impact_hdg    = hdg;
 835     _impact_pitch  = pitch;
 836     _impact_roll   = roll;
 837
 838     SGPropertyNode *n = props->getNode("impact", true);
 839     if (object)
 840         n->setStringValue("type", object->getTypeString());
 841     else
 842         n->setStringValue("type", "terrain");
 843
 844     n->setDoubleValue("longitude-deg", _impact_lon);
 845     n->setDoubleValue("latitude-deg", _impact_lat);
 846     n->setDoubleValue("elevation-m", _impact_elev);
 847     n->setDoubleValue("heading-deg", _impact_hdg);
 848     n->setDoubleValue("pitch-deg", _impact_pitch);
 849     n->setDoubleValue("roll-deg", _impact_roll);
 850     n->setDoubleValue("speed-mps", _impact_speed);
 851
 852     _impact_report_node->setStringValue(props->getPath());
 853 }
 854
 855 SGVec3d FGAIBallistic::getCartUserPos() const {
 856     SGVec3d cartUserPos = SGVec3d::fromGeod(userpos);
 857     return cartUserPos;
 858 }
 859
 860 SGVec3d FGAIBallistic::getCartHitchPos() const{
 861
 862     // convert geodetic positions to geocentered
 863     SGVec3d cartuserPos = getCartUserPos();
 864     SGVec3d cartPos = getCartPos();
 865
 866     // Transform to the right coordinate frame, configuration is done in
 867     // the x-forward, y-right, z-up coordinates (feet), computation
 868     // in the simulation usual body x-forward, y-right, z-down coordinates
 869     // (meters) )
 870     SGVec3d _off(_x_offset * SG_FEET_TO_METER,
 871         _y_offset * SG_FEET_TO_METER,
 872         -_z_offset * SG_FEET_TO_METER);
 873
 874     // Transform the user position to the horizontal local coordinate system.
 875     SGQuatd hlTrans = SGQuatd::fromLonLat(userpos);
 876
 877     // and postrotate the orientation of the user model wrt the horizontal
 878     // local frame
 879     hlTrans *= SGQuatd::fromYawPitchRollDeg(
 880         manager->get_user_heading(),
 881         manager->get_user_pitch(),
 882         manager->get_user_roll());
 883
 884     // The offset converted to the usual body fixed coordinate system
 885     // rotated to the earth-fixed coordinates axis
 886     SGVec3d off = hlTrans.backTransform(_off);
 887
 888     // Add the position offset of the user model to get the geocentered position
 889     SGVec3d offsetPos = cartuserPos + off;
 890
 891     return offsetPos;
 892 }
 893
 894 void FGAIBallistic::setHitchPos(){
 895     // convert the hitch geocentered position to geodetic
 896     SGVec3d carthitchPos = getCartHitchPos();
 897
 898     SGGeodesy::SGCartToGeod(carthitchPos, hitchpos);
 899 }
 900
 901 double FGAIBallistic::getDistanceLoadToHitch() const {
 902     //calculate the distance load to hitch
 903     SGVec3d carthitchPos = getCartHitchPos();
 904     SGVec3d cartPos = getCartPos();
 905
 906     SGVec3d diff = carthitchPos - cartPos;
 907     double distance = norm(diff);
 908     return distance * SG_METER_TO_FEET;
 909 }
 910
 911 void FGAIBallistic::setHitchVelocity(double dt) {
 912     //calculate the distance from the previous hitch position
 913     SGVec3d carthitchPos = getCartHitchPos();
 914     SGVec3d diff = carthitchPos - _oldcarthitchPos;
 915
 916     double distance = norm(diff);
 917
 918     //calculate speed knots
 919     speed = (distance/dt) * SG_MPS_TO_KT;
 920
 921     //now calulate the angle between the old and current hitch positions (degrees)
 922     double angle = 0;
 923     double daltM = hitchpos.getElevationM() - oldhitchpos.getElevationM();
 924
 925     if (fabs(distance) < SGLimits<float>::min()) {
 926         angle = 0;
 927     } else {
 928         double sAngle = daltM/distance;
 929         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 930         angle = SGMiscd::rad2deg(asin(sAngle));
 931     }
 932
 933     _elevation = angle;
 934
 935     //calculate the bearing of the new hitch position from the old
 936     double az1, az2, dist;
 937
 938     geo_inverse_wgs_84(oldhitchpos, hitchpos, &az1, &az2, &dist);
 939
 940     _azimuth = az1;
 941
 942     // and finally store the new values
 943     _oldcarthitchPos = carthitchPos;
 944     oldhitchpos = hitchpos;
 945 }
 946
 947 double FGAIBallistic::getElevLoadToHitch() const {
 948     // now the angle, positive angles are upwards
 949     double distance = getDistanceLoadToHitch() * SG_FEET_TO_METER;
 950     double angle = 0;
 951     double daltM = hitchpos.getElevationM() - pos.getElevationM();
 952
 953     if (fabs(distance) < SGLimits<float>::min()) {
 954         angle = 0;
 955     } else {
 956         double sAngle = daltM/distance;
 957         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 958         angle = SGMiscd::rad2deg(asin(sAngle));
 959     }
 960
 961     return angle;
 962 }
 963
 964 double FGAIBallistic::getBearingLoadToHitch() const {
 965     //calculate the bearing and range of the second pos from the first
 966     double az1, az2, distance;
 967
 968     geo_inverse_wgs_84(pos, hitchpos, &az1, &az2, &distance);
 969
 970     return az1;
 971 }
 972
 973 double FGAIBallistic::getRelBrgHitchToUser() const {
 974     //calculate the relative bearing
 975     double az1, az2, distance;
 976
 977     geo_inverse_wgs_84(hitchpos, userpos, &az1, &az2, &distance);
 978
 979     double rel_brg = az1 - hdg;
 980
 981     if (rel_brg > 180)
 982         rel_brg -= 360;
 983
 984     return rel_brg;
 985 }
 986
 987 double FGAIBallistic::getElevHitchToUser() const {
 988
 989     //calculate the distance from the user position
 990     SGVec3d carthitchPos = getCartHitchPos();
 991     SGVec3d cartuserPos = getCartUserPos();
 992
 993     SGVec3d diff = cartuserPos - carthitchPos;
 994
 995     double distance = norm(diff);
 996     double angle = 0;
 997
 998     double daltM = userpos.getElevationM() - hitchpos.getElevationM();
 999
1000     // now the angle, positive angles are upwards
1001     if (fabs(distance) < SGLimits<float>::min()) {
1002         angle = 0;
1003     } else {
1004         double sAngle = daltM/distance;
1005         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
1006         angle = SGMiscd::rad2deg(asin(sAngle));
1007     }
1008
1009     return angle;
1010 }
1011
1012 void FGAIBallistic::setTgtOffsets(double dt, double coeff){
1013     double c = dt / (coeff + dt);
1014
1015     _x_offset = (_tgt_x_offset * c) + (_x_offset * (1 - c));
1016     _y_offset = (_tgt_y_offset * c) + (_y_offset * (1 - c));
1017     _z_offset = (_tgt_z_offset * c) + (_z_offset * (1 - c));
1018 }
1019
1020 void FGAIBallistic::formateToAC(double dt){
1021
1022     setTgtOffsets(dt, 25);
1023     setHitchPos();
1024     setHitchVelocity(dt);
1025
1026     // elapsed time has a random initialisation so that each
1027     // wingman moves differently
1028     _elapsed_time += dt;
1029
1030     // we derive a sine based factor to give us smoothly
1031     // varying error between -1 and 1
1032     double factor  = sin(SGMiscd::deg2rad(_elapsed_time * 10));
1033     double r_angle = 5 * factor;
1034     double p_angle = 2.5 * factor;
1035     double h_angle = 5 * factor;
1036     double h_feet  = 3 * factor;
1037
1038     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
1039     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
1040
1041     if (getHtAGL()){
1042
1043         if(_ht_agl_ft <= 10) {
1044             _height = userpos.getElevationFt();
1045         } else if (_ht_agl_ft > 10 && _ht_agl_ft <= 150 ) {
1046             setHt(userpos.getElevationFt(), dt, 1.0);
1047         } else if (_ht_agl_ft > 150 && _ht_agl_ft <= 250) {
1048             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.75);
1049         } else
1050             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.5);
1051
1052         pos.setElevationFt(_height);
1053     }
1054
1055     // these calculations are unreliable at slow speeds
1056     if(speed >= 10) {
1057         setHdg(_azimuth + h_angle, dt, 0.9);
1058         setPch(_elevation + p_angle + _pitch_offset, dt, 0.9);
1059
1060         if (roll <= 115 && roll >= -115)
1061             setBnk(manager->get_user_roll() + r_angle + _roll_offset, dt, 0.5);
1062         else
1063             roll = manager->get_user_roll() + r_angle + _roll_offset;
1064
1065     } else {
1066         setHdg(manager->get_user_heading(), dt, 0.9);
1067         setPch(manager->get_user_pitch() + _pitch_offset, dt, 0.9);
1068         setBnk(manager->get_user_roll() + _roll_offset, dt, 0.9);
1069     }
1070
1071     setSpeed(speed);
1072 }
1073 // end AIBallistic