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     _elevation(0),
  44     _aero_stabilised(false),
  45     _drag_area(0.007),
  46     _life_timer(0.0),
  47 _gravity(32.1740485564),
  48     _buoyancy(0),
  49     _random(false),
  50     _ht_agl_ft(0),
  51     _load_resistance(0),
  52     _solid(false),
  53     _report_collision(false),
  54     _report_impact(false),
  55 _wind(true),
  56     _impact_report_node(fgGetNode("/ai/models/model-impact", true)),
  57     _force_stabilised(false),
  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 bool FGAIBallistic::init(bool search_in_AI_path) {
 121     FGAIBase::init(search_in_AI_path);
 122
 123     _impact_reported = false;
 124     _collision_reported = false;
 125     invisible = false;
 126
 127     _elapsed_time += (sg_random() * 100);
 128
 129     props->setStringValue("material/name", "");
 130     props->setStringValue("name", _name.c_str());
 131     props->setStringValue("submodels/path", _submodel.c_str());
 132
 133     // start with high value so that animations don't trigger yet
 134     _ht_agl_ft = 1e10;
 135     hdg = _azimuth;
 136     pitch = _elevation;
 137     roll = _rotation;
 138
 139     Transform();
 140
 141     return true;
 142 }
 143
 144 void FGAIBallistic::bind() {
 145     //    FGAIBase::bind();
 146
 147     props->tie("sim/time/elapsed-sec",
 148         SGRawValueMethods<FGAIBallistic,double>(*this,
 149         &FGAIBallistic::_getTime));
 150     props->tie("mass-slug",
 151         SGRawValueMethods<FGAIBallistic,double>(*this,
 152         &FGAIBallistic::getMass));
 153     props->tie("material/load-resistance",
 154                 SGRawValuePointer<double>(&_load_resistance));
 155     props->tie("material/solid",
 156                 SGRawValuePointer<bool>(&_solid));
 157     props->tie("altitude-agl-ft",
 158                 SGRawValuePointer<double>(&_ht_agl_ft));
 159     props->tie("controls/slave-to-ac",
 160         SGRawValueMethods<FGAIBallistic,bool>
 161         (*this, &FGAIBallistic::getSlaved, &FGAIBallistic::setSlaved));
 162     props->tie("controls/invisible",
 163         SGRawValuePointer<bool>(&invisible));
 164
 165     if(_external_force){
 166         props->tie("controls/force_stabilized",
 167             SGRawValuePointer<bool>(&_force_stabilised));
 168         props->tie("position/global-x",
 169             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosX, 0));
 170         props->tie("position/global-y",
 171             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosY, 0));
 172         props->tie("position/global-z",
 173             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getCartPosZ, 0));
 174         props->tie("velocities/vertical-speed-fps",
 175             SGRawValuePointer<double>(&vs));
 176         props->tie("velocities/true-airspeed-kt",
 177             SGRawValuePointer<double>(&speed));
 178         props->tie("velocities/horizontal-speed-fps",
 179             SGRawValuePointer<double>(&hs));
 180         props->tie("position/altitude-ft",
 181             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getAltitude, &FGAIBase::_setAltitude));
 182         props->tie("position/latitude-deg",
 183             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLatitude, &FGAIBase::_setLatitude));
 184         props->tie("position/longitude-deg",
 185             SGRawValueMethods<FGAIBase,double>(*this, &FGAIBase::_getLongitude, &FGAIBase::_setLongitude));
 186         props->tie("orientation/hdg-deg",
 187             SGRawValuePointer<double>(&hdg));
 188         props->tie("orientation/pitch-deg",
 189             SGRawValuePointer<double>(&pitch));
 190         props->tie("orientation/roll-deg",
 191             SGRawValuePointer<double>(&roll));
 192         props->tie("controls/slave-load-to-ac",
 193             SGRawValueMethods<FGAIBallistic,bool>
 194             (*this, &FGAIBallistic::getSlavedLoad, &FGAIBallistic::setSlavedLoad));
 195         props->tie("position/load-offset",
 196             SGRawValueMethods<FGAIBallistic,double>
 197             (*this, &FGAIBallistic::getLoadOffset, &FGAIBallistic::setLoadOffset));
 198         props->tie("load/distance-to-hitch-ft",
 199             SGRawValueMethods<FGAIBallistic,double>
 200             (*this, &FGAIBallistic::getDistanceLoadToHitch));
 201         props->tie("load/elevation-to-hitch-deg",
 202             SGRawValueMethods<FGAIBallistic,double>
 203             (*this, &FGAIBallistic::getElevLoadToHitch));
 204         props->tie("load/bearing-to-hitch-deg",
 205             SGRawValueMethods<FGAIBallistic,double>
 206             (*this, &FGAIBallistic::getBearingLoadToHitch));
 207     }
 208
 209 }
 210
 211 void FGAIBallistic::unbind() {
 212     //    FGAIBase::unbind();
 213
 214     props->untie("sim/time/elapsed-sec");
 215     props->untie("mass-slug");
 216     props->untie("material/load-resistance");
 217     props->untie("material/solid");
 218     props->untie("altitude-agl-ft");
 219     props->untie("controls/slave-to-ac");
 220     props->untie("controls/invisible");
 221
 222     if(_external_force){
 223         props->untie("position/global-y");
 224         props->untie("position/global-x");
 225         props->untie("position/global-z");
 226         props->untie("velocities/vertical-speed-fps");
 227         props->untie("velocities/true-airspeed-kt");
 228         props->untie("velocities/horizontal-speed-fps");
 229         props->untie("position/altitude-ft");
 230         props->untie("position/latitude-deg");
 231         props->untie("position/longitude-deg");
 232         props->untie("position/ht-agl-ft");
 233         props->untie("orientation/hdg-deg");
 234         props->untie("orientation/pitch-deg");
 235         props->untie("orientation/roll-deg");
 236         props->untie("controls/force_stabilized");
 237         props->untie("position/load-offset");
 238         props->untie("load/distance-to-hitch-ft");
 239         props->untie("load/elevation-to-hitch-deg");
 240         props->untie("load/bearing-to-hitch-deg");
 241     }
 242 }
 243
 244 void FGAIBallistic::update(double dt) {
 245     FGAIBase::update(dt);
 246     _setUserPos();
 247
 248     if (_slave_to_ac){
 249         slaveToAC(dt);
 250         Transform();
 251         setHitchVelocity(dt);
 252     } else if (_formate_to_ac){
 253         formateToAC(dt);
 254         Transform();
 255         setHitchVelocity(dt);
 256     } else if (!invisible){
 257     Run(dt);
 258     Transform();
 259 }
 260
 261 }
 262
 263 void FGAIBallistic::setAzimuth(double az) {
 264     hdg = _azimuth = az;
 265 }
 266
 267 void FGAIBallistic::setElevation(double el) {
 268     pitch = _elevation = el;
 269 }
 270
 271 void FGAIBallistic::setRoll(double rl) {
 272     roll = _rotation = rl;
 273 }
 274
 275 void FGAIBallistic::setStabilisation(bool val) {
 276     _aero_stabilised = val;
 277 }
 278
 279 void FGAIBallistic::setForceStabilisation(bool val) {
 280     _force_stabilised = val;
 281 }
 282
 283 void FGAIBallistic::setNoRoll(bool nr) {
 284     no_roll = nr;
 285 }
 286
 287 void FGAIBallistic::setDragArea(double a) {
 288     _drag_area = a;
 289 }
 290
 291 void FGAIBallistic::setLife(double seconds) {
 292     life = seconds;
 293 }
 294
 295 void FGAIBallistic::setBuoyancy(double fpss) {
 296     _buoyancy = fpss;
 297 }
 298
 299 void FGAIBallistic::setWind_from_east(double fps) {
 300     _wind_from_east = fps;
 301 }
 302
 303 void FGAIBallistic::setWind_from_north(double fps) {
 304     _wind_from_north = fps;
 305 }
 306
 307 void FGAIBallistic::setWind(bool val) {
 308     _wind = val;
 309 }
 310
 311 void FGAIBallistic::setCd(double c) {
 312     _Cd = c;
 313 }
 314
 315 void FGAIBallistic::setMass(double m) {
 316     _mass = m;
 317 }
 318
 319 void FGAIBallistic::setWeight(double w) {
 320     _weight_lb = w;
 321 }
 322 void FGAIBallistic::setRandom(bool r) {
 323     _random = r;
 324 }
 325
 326 void FGAIBallistic::setImpact(bool i) {
 327     _report_impact = i;
 328 }
 329
 330 void FGAIBallistic::setCollision(bool c) {
 331     _report_collision = c;
 332 }
 333
 334 void FGAIBallistic::setExternalForce(bool f) {
 335     _external_force = f;
 336 }
 337
 338 void FGAIBallistic::setImpactReportNode(const string& path) {
 339
 340     if (!path.empty())
 341         _impact_report_node = fgGetNode(path.c_str(), true);
 342 }
 343
 344 void FGAIBallistic::setName(const string& n) {
 345     _name = n;
 346 }
 347
 348 void FGAIBallistic::setSMPath(const string& s) {
 349     _submodel = s;
 350 }
 351
 352 void FGAIBallistic::setFuseRange(double f) {
 353     _fuse_range = f;
 354 }
 355
 356 void FGAIBallistic::setSubID(int i) {
 357     _subID = i;
 358 }
 359
 360 void FGAIBallistic::setSubmodel(const string& s) {
 361     _submodel = s;
 362 }
 363
 364 void FGAIBallistic::setGroundOffset(double g) {
 365     _ground_offset = g;
 366 }
 367
 368 void FGAIBallistic::setLoadOffset(double l) {
 369     _load_offset = l;
 370 }
 371
 372 double FGAIBallistic::getLoadOffset() const {
 373     return _load_offset;
 374 }
 375
 376 void FGAIBallistic::setSlaved(bool s) {
 377     _slave_to_ac = s;
 378 }
 379
 380 void FGAIBallistic::setFormate(bool f) {
 381     _formate_to_ac = f;
 382 }
 383
 384 void FGAIBallistic::setContentsNode(const string& path) {
 385     if (!path.empty()) {
 386         _contents_node = fgGetNode(path.c_str(), true);
 387     }
 388 }
 389
 390 bool FGAIBallistic::getSlaved() const {
 391     return _slave_to_ac;
 392 }
 393
 394 double FGAIBallistic::getMass() const {
 395     return _mass;
 396 }
 397
 398 double FGAIBallistic::getContents() {
 399     if(_contents_node)
 400         _contents_lb = _contents_node->getChild("level-lbs",0,1)->getDoubleValue();
 401     return _contents_lb;
 402 }
 403
 404 void FGAIBallistic::setContents(double c) {
 405     if(_contents_node)
 406         _contents_lb = _contents_node->getChild("level-gal_us",0,1)->setDoubleValue(c);
 407 }
 408
 409 void FGAIBallistic::setSlavedLoad(bool l) {
 410     _slave_load_to_ac = l;
 411 }
 412
 413 bool FGAIBallistic::getSlavedLoad() const {
 414     return _slave_load_to_ac;
 415 }
 416
 417 void FGAIBallistic::setForcePath(const string& p) {
 418     _force_path = p;
 419     if (!_force_path.empty()) {
 420         SGPropertyNode *fnode = fgGetNode(_force_path.c_str(), 0, true );
 421         _force_node = fnode->getChild("force-lb", 0, true);
 422         _force_azimuth_node = fnode->getChild("force-azimuth-deg", 0, true);
 423         _force_elevation_node = fnode->getChild("force-elevation-deg", 0, true);
 424     }
 425 }
 426
 427 bool FGAIBallistic::getHtAGL(){
 428
 429     if (globals->get_scenery()->get_elevation_m(SGGeod::fromGeodM(pos, 10000),
 430                                                 _elevation_m, &_material)){
 431             _ht_agl_ft = pos.getElevationFt() - _elevation_m * SG_METER_TO_FEET;
 432             if (_material) {
 433                 const vector<string>& names = _material->get_names();
 434
 435                 _solid = _material->get_solid();
 436                 _load_resistance = _material->get_load_resistance();
 437                 _frictionFactor =_material->get_friction_factor();
 438                 if (!names.empty())
 439                     props->setStringValue("material/name", names[0].c_str());
 440                 else
 441                     props->setStringValue("material/name", "");
 442                 /*cout << "material " << mat_name
 443                 << " solid " << _solid
 444                 << " load " << _load_resistance
 445                 << " frictionFactor " << frictionFactor
 446                 << endl;*/
 447             }
 448             return true;
 449     } else {
 450         return false;
 451     }
 452
 453 }
 454
 455 double FGAIBallistic::getRecip(double az){
 456     // calculate the reciprocal of the input azimuth
 457     if(az - 180 < 0){
 458         return az + 180;
 459     } else {
 460         return az - 180;
 461     }
 462 }
 463
 464 void FGAIBallistic::setPch(double e, double dt, double coeff){
 465     double c = dt / (coeff + dt);
 466     pitch = (e * c) + (pitch * (1 - c));
 467 }
 468
 469 void FGAIBallistic::setBnk(double r, double dt, double coeff){
 470     double c = dt / (coeff + dt);
 471     roll = (r * c) + (roll * (1 - c));
 472 }
 473
 474 void FGAIBallistic::setHt(double h, double dt, double coeff){
 475     double c = dt / (coeff + dt);
 476     _height = (h * c) + (_height * (1 - c));
 477 }
 478
 479 void FGAIBallistic::setHdg(double az, double dt, double coeff){
 480     double recip = getRecip(hdg);
 481     double c = dt / (coeff + dt);
 482     //we need to ensure that we turn the short way to the new hdg
 483     if (az < recip && az < hdg && hdg > 180) {
 484         hdg = ((az + 360) * c) + (hdg * (1 - c));
 485     } else if (az > recip && az > hdg && hdg <= 180){
 486         hdg = ((az - 360) * c) + (hdg * (1 - c));
 487     } else {
 488         hdg = (az * c) + (hdg * (1 - c));
 489     }
 490     }
 491
 492 double  FGAIBallistic::getTgtXOffset() const {
 493     return _tgt_x_offset;
 494 }
 495
 496 double  FGAIBallistic::getTgtYOffset() const {
 497     return _tgt_y_offset;
 498 }
 499
 500 double  FGAIBallistic::getTgtZOffset() const {
 501     return _tgt_z_offset;
 502 }
 503
 504 void FGAIBallistic::setTgtXOffset(double x){
 505     _tgt_x_offset = x;
 506 }
 507
 508 void FGAIBallistic::setTgtYOffset(double y){
 509     _tgt_y_offset = y;
 510 }
 511
 512 void FGAIBallistic::setTgtZOffset(double z){
 513     _tgt_z_offset = z;
 514 }
 515
 516 void FGAIBallistic::slaveToAC(double dt){
 517
 518     setHitchPos();
 519     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 520     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 521     pos.setElevationFt(hitchpos.getElevationFt());
 522     setHeading(manager->get_user_heading());
 523     setPitch(manager->get_user_pitch() + _pitch_offset);
 524     setBank(manager->get_user_roll() + _roll_offset);
 525     setSpeed(manager->get_user_speed());
 526     //update the mass (slugs)
 527     _mass = (_weight_lb + getContents()) / slugs_to_lbs;
 528
 529     /*cout <<"_mass "<<_mass <<" " << getContents()
 530     <<" " << getContents() / slugs_to_lbs << endl;*/
 531 }
 532
 533 void FGAIBallistic::Run(double dt) {
 534     _life_timer += dt;
 535
 536     // if life = -1 the object does not die
 537     if (_life_timer > life && life != -1)
 538         setDie(true);
 539
 540     //set the contents in the appropriate tank or other property in the parent to zero
 541     setContents(0);
 542
 543     //randomise Cd by +- 5%
 544     if (_random)
 545         _Cd = _Cd * 0.95 + (0.05 * sg_random());
 546
 547     // Adjust Cd by Mach number. The equations are based on curves
 548     // for a conventional shell/bullet (no boat-tail).
 549     double Cdm;
 550
 551     if (Mach < 0.7)
 552         Cdm = 0.0125 * Mach + _Cd;
 553     else if (Mach < 1.2 )
 554         Cdm = 0.3742 * pow(Mach, 2) - 0.252 * Mach + 0.0021 + _Cd;
 555     else
 556         Cdm = 0.2965 * pow(Mach, -1.1506) + _Cd;
 557
 558     //cout << "Mach " << Mach << " Cdm " << Cdm << "// ballistic speed kts "<< speed <<  endl;
 559
 560     // drag = Cd * 0.5 * rho * speed * speed * drag_area;
 561     // rho is adjusted for altitude in void FGAIBase::update,
 562     // using Standard Atmosphere (sealevel temperature 15C)
 563     // acceleration = drag/mass;
 564     // adjust speed by drag
 565     speed -= (Cdm * 0.5 * rho * speed * speed * _drag_area/_mass) * dt;
 566
 567     // don't let speed become negative
 568     if ( speed < 0.0 )
 569         speed = 0.0;
 570
 571     double speed_fps = speed * SG_KT_TO_FPS;
 572     //double hs;
 573
 574     // calculate vertical and horizontal speed components
 575     if (speed == 0.0) {
 576         hs = vs = 0.0;
 577     } else {
 578         vs = sin( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 579         hs = cos( _elevation * SG_DEGREES_TO_RADIANS ) * speed_fps;
 580     }
 581
 582     //resolve horizontal speed into north and east components:
 583     double speed_north_fps = cos(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 584     double speed_east_fps = sin(_azimuth / SG_RADIANS_TO_DEGREES) * hs;
 585
 586     // convert horizontal speed (fps) to degrees per second
 587     double speed_north_deg_sec = speed_north_fps / ft_per_deg_lat;
 588     double speed_east_deg_sec  = speed_east_fps / ft_per_deg_lon;
 589
 590     // if wind not required, set to zero
 591     if (!_wind) {
 592         _wind_from_north = 0;
 593         _wind_from_east = 0;
 594     } else {
 595         _wind_from_north = manager->get_wind_from_north();
 596         _wind_from_east = manager->get_wind_from_east();
 597     }
 598
 599     //calculate velocity due to external force
 600     double force_speed_north_deg_sec = 0;
 601     double force_speed_east_deg_sec = 0;
 602     double vs_force_fps = 0;
 603     double hs_force_fps = 0;
 604     double v_force_acc_fpss = 0;
 605     double force_speed_north_fps = 0;
 606     double force_speed_east_fps = 0;
 607     double h_force_lbs = 0;
 608     double normal_force_lbs = 0;
 609     double normal_force_fpss = 0;
 610     double static_friction_force_lbs = 0;
 611     double dynamic_friction_force_lbs = 0;
 612     double friction_force_speed_north_fps = 0;
 613     double friction_force_speed_east_fps = 0;
 614     double friction_force_speed_north_deg_sec = 0;
 615     double friction_force_speed_east_deg_sec = 0;
 616     double force_elevation_deg = 0;
 617
 618     if (_external_force) {
 619         SGPropertyNode *n = fgGetNode(_force_path.c_str(), true);
 620         double force_lbs            = n->getChild("force-lb", 0, true)->getDoubleValue();
 621         force_elevation_deg         = n->getChild("force-elevation-deg", 0, true)->getDoubleValue();
 622         double force_azimuth_deg    = n->getChild("force-azimuth-deg", 0, true)->getDoubleValue();
 623
 624         //resolve force into vertical and horizontal components:
 625         double v_force_lbs = force_lbs * sin( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 626         h_force_lbs = force_lbs * cos( force_elevation_deg * SG_DEGREES_TO_RADIANS );
 627
 628         //ground interaction
 629
 630         if (getHtAGL()){
 631             double deadzone = 0.1;
 632
 633             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 634                 normal_force_lbs = (_mass * slugs_to_lbs) - v_force_lbs;
 635
 636                 if ( normal_force_lbs < 0 )
 637                     normal_force_lbs = 0;
 638
 639                 pos.setElevationFt(0 + _ground_offset);
 640                 if (vs < 0)
 641                     vs = -vs * 0.5;
 642
 643                 // calculate friction
 644                 // we assume a static Coefficient of Friction (mu) of 0.62 (wood on concrete)
 645                 double mu = 0.62;
 646
 647                 static_friction_force_lbs = mu * normal_force_lbs * _frictionFactor;
 648
 649                 //adjust horizontal force. We assume that a speed of <= 5 fps is static
 650                 if (h_force_lbs <= static_friction_force_lbs && hs <= 5){
 651                     h_force_lbs = hs = 0;
 652                     speed_north_fps = speed_east_fps = 0;
 653                 } else
 654                     dynamic_friction_force_lbs = (static_friction_force_lbs * 0.95);
 655
 656                 //ignore wind when on the ground for now
 657                 //TODO fix this
 658                 _wind_from_north = 0;
 659                 _wind_from_east = 0;
 660
 661             }
 662
 663         }
 664
 665         //acceleration = (force(lbsf)/mass(slugs))
 666         v_force_acc_fpss = v_force_lbs/_mass;
 667         normal_force_fpss = normal_force_lbs/_mass;
 668         double h_force_acc_fpss = h_force_lbs/_mass;
 669         double dynamic_friction_acc_fpss = dynamic_friction_force_lbs/_mass;
 670
 671         // velocity = acceleration * dt
 672         hs_force_fps = h_force_acc_fpss * dt;
 673         double friction_force_fps = dynamic_friction_acc_fpss * dt;
 674
 675         //resolve horizontal speeds into north and east components:
 676         force_speed_north_fps   = cos(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 677         force_speed_east_fps    = sin(force_azimuth_deg * SG_DEGREES_TO_RADIANS) * hs_force_fps;
 678
 679         friction_force_speed_north_fps = cos(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 680         friction_force_speed_east_fps  = sin(getRecip(hdg) * SG_DEGREES_TO_RADIANS) * friction_force_fps;
 681
 682         // convert horizontal speed (fps) to degrees per second
 683         force_speed_north_deg_sec = force_speed_north_fps / ft_per_deg_lat;
 684         force_speed_east_deg_sec  = force_speed_east_fps / ft_per_deg_lon;
 685
 686         friction_force_speed_north_deg_sec = friction_force_speed_north_fps / ft_per_deg_lat;
 687         friction_force_speed_east_deg_sec  = friction_force_speed_east_fps / ft_per_deg_lon;
 688     }
 689
 690     // convert wind speed (fps) to degrees lat/lon per second
 691     double wind_speed_from_north_deg_sec = _wind_from_north / ft_per_deg_lat;
 692     double wind_speed_from_east_deg_sec  = _wind_from_east / ft_per_deg_lon;
 693
 694     //recombine the horizontal velocity components
 695     hs = sqrt(((speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps)
 696         * (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 697         + ((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)
 698         * (speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps)));
 699
 700     if (hs <= 0.00001)
 701         hs = 0;
 702
 703     // adjust vertical speed for acceleration of gravity, buoyancy, and vertical force
 704     vs -= (_gravity - _buoyancy - v_force_acc_fpss - normal_force_fpss) * dt;
 705
 706     if (vs <= 0.00001 && vs >= -0.00001)
 707         vs = 0;
 708
 709     // set new position
 710     if(_slave_load_to_ac) {
 711         setHitchPos();
 712         pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
 713         pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
 714         pos.setElevationFt(hitchpos.getElevationFt());
 715
 716         if (getHtAGL()){
 717             double deadzone = 0.1;
 718
 719             if (_ht_agl_ft <= (0 + _ground_offset + deadzone) && _solid){
 720                 pos.setElevationFt(0 + _ground_offset);
 721             } else {
 722                 pos.setElevationFt(hitchpos.getElevationFt() + _load_offset);
 723             }
 724
 725         }
 726     } else {
 727         pos.setLatitudeDeg( pos.getLatitudeDeg()
 728             + (speed_north_deg_sec - wind_speed_from_north_deg_sec
 729             + force_speed_north_deg_sec + friction_force_speed_north_deg_sec) * dt );
 730         pos.setLongitudeDeg( pos.getLongitudeDeg()
 731             + (speed_east_deg_sec - wind_speed_from_east_deg_sec
 732             + force_speed_east_deg_sec + friction_force_speed_east_deg_sec) * dt );
 733         pos.setElevationFt(pos.getElevationFt() + vs * dt);
 734     }
 735
 736     // recalculate total speed
 737     if ( vs == 0 && hs == 0)
 738         speed = 0;
 739     else
 740         speed = sqrt( vs * vs + hs * hs) / SG_KT_TO_FPS;
 741
 742     // recalculate elevation and azimuth (velocity vectors)
 743     _elevation = atan2( vs, hs ) * SG_RADIANS_TO_DEGREES;
 744     _azimuth =  atan2((speed_east_fps + force_speed_east_fps + friction_force_speed_east_fps),
 745         (speed_north_fps + force_speed_north_fps + friction_force_speed_north_fps))
 746         * SG_RADIANS_TO_DEGREES;
 747
 748     // rationalise azimuth
 749     if (_azimuth < 0)
 750         _azimuth += 360;
 751
 752     if (_aero_stabilised) { // we simulate rotational moment of inertia by using a filter
 753         const double coeff = 0.9;
 754
 755         // we assume a symetrical MI about the pitch and yaw axis
 756         setPch(_elevation, dt, coeff);
 757         setHdg(_azimuth, dt, coeff);
 758     } else if (_force_stabilised) { // we simulate rotational moment of inertia by using a filter
 759         const double coeff = 0.9;
 760         double ratio = h_force_lbs/(_mass * slugs_to_lbs);
 761
 762         if (ratio >  1) ratio =  1;
 763         if (ratio < -1) ratio = -1;
 764
 765         double force_pitch = acos(ratio) * SG_RADIANS_TO_DEGREES;
 766
 767         if (force_pitch <= force_elevation_deg)
 768             force_pitch = force_elevation_deg;
 769
 770         // we assume a symetrical MI about the pitch and yaw axis
 771         setPch(force_pitch,dt, coeff);
 772         setHdg(_azimuth, dt, coeff);
 773     }
 774
 775     //do impacts and collisions
 776     if (_report_impact && !_impact_reported)
 777         handle_impact();
 778
 779     if (_report_collision && !_collision_reported)
 780         handle_collision();
 781
 782     // set destruction flag if altitude less than sea level -1000
 783     if (altitude_ft < -1000.0 && life != -1)
 784         setDie(true);
 785
 786 }  // end Run
 787
 788 double FGAIBallistic::_getTime() const {
 789     return _life_timer;
 790 }
 791
 792 void FGAIBallistic::handle_impact() {
 793
 794     // try terrain intersection
 795     if(!getHtAGL())
 796         return;
 797
 798     if (_ht_agl_ft <= 0) {
 799         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: terrain impact");
 800         report_impact(_elevation_m);
 801         _impact_reported = true;
 802
 803         if (life == -1){
 804             invisible = true;
 805         } else if (_subID == 0)  // kill the AIObject if there is no subsubmodel
 806             setDie(true);
 807     }
 808 }
 809
 810 void FGAIBallistic::handle_collision()
 811 {
 812     const FGAIBase *object = manager->calcCollision(pos.getElevationFt(),
 813             pos.getLatitudeDeg(),pos.getLongitudeDeg(), _fuse_range);
 814
 815     if (object) {
 816         SG_LOG(SG_GENERAL, SG_DEBUG, "AIBallistic: object hit");
 817         report_impact(pos.getElevationM(), object);
 818         _collision_reported = true;
 819     }
 820 }
 821
 822 void FGAIBallistic::report_impact(double elevation, const FGAIBase *object)
 823 {
 824     _impact_lat    = pos.getLatitudeDeg();
 825     _impact_lon    = pos.getLongitudeDeg();
 826     _impact_elev   = elevation;
 827     _impact_speed  = speed * SG_KT_TO_MPS;
 828     _impact_hdg    = hdg;
 829     _impact_pitch  = pitch;
 830     _impact_roll   = roll;
 831
 832     SGPropertyNode *n = props->getNode("impact", true);
 833     if (object)
 834         n->setStringValue("type", object->getTypeString());
 835     else
 836         n->setStringValue("type", "terrain");
 837
 838     n->setDoubleValue("longitude-deg", _impact_lon);
 839     n->setDoubleValue("latitude-deg", _impact_lat);
 840     n->setDoubleValue("elevation-m", _impact_elev);
 841     n->setDoubleValue("heading-deg", _impact_hdg);
 842     n->setDoubleValue("pitch-deg", _impact_pitch);
 843     n->setDoubleValue("roll-deg", _impact_roll);
 844     n->setDoubleValue("speed-mps", _impact_speed);
 845
 846     _impact_report_node->setStringValue(props->getPath());
 847 }
 848
 849 SGVec3d FGAIBallistic::getCartUserPos() const {
 850     SGVec3d cartUserPos = SGVec3d::fromGeod(userpos);
 851     return cartUserPos;
 852 }
 853
 854 SGVec3d FGAIBallistic::getCartHitchPos() const{
 855
 856     // convert geodetic positions to geocentered
 857     SGVec3d cartuserPos = getCartUserPos();
 858     SGVec3d cartPos = getCartPos();
 859
 860     // Transform to the right coordinate frame, configuration is done in
 861     // the x-forward, y-right, z-up coordinates (feet), computation
 862     // in the simulation usual body x-forward, y-right, z-down coordinates
 863     // (meters) )
 864     SGVec3d _off(_x_offset * SG_FEET_TO_METER,
 865         _y_offset * SG_FEET_TO_METER,
 866         -_z_offset * SG_FEET_TO_METER);
 867
 868     // Transform the user position to the horizontal local coordinate system.
 869     SGQuatd hlTrans = SGQuatd::fromLonLat(userpos);
 870
 871     // and postrotate the orientation of the user model wrt the horizontal
 872     // local frame
 873     hlTrans *= SGQuatd::fromYawPitchRollDeg(
 874         manager->get_user_heading(),
 875         manager->get_user_pitch(),
 876         manager->get_user_roll());
 877
 878     // The offset converted to the usual body fixed coordinate system
 879     // rotated to the earth-fixed coordinates axis
 880     SGVec3d off = hlTrans.backTransform(_off);
 881
 882     // Add the position offset of the user model to get the geocentered position
 883     SGVec3d offsetPos = cartuserPos + off;
 884
 885     return offsetPos;
 886 }
 887
 888 void FGAIBallistic::setHitchPos(){
 889     // convert the hitch geocentered position to geodetic
 890     SGVec3d carthitchPos = getCartHitchPos();
 891
 892     SGGeodesy::SGCartToGeod(carthitchPos, hitchpos);
 893 }
 894
 895 double FGAIBallistic::getDistanceLoadToHitch() const {
 896     //calculate the distance load to hitch
 897     SGVec3d carthitchPos = getCartHitchPos();
 898     SGVec3d cartPos = getCartPos();
 899
 900     SGVec3d diff = carthitchPos - cartPos;
 901     double distance = norm(diff);
 902     return distance * SG_METER_TO_FEET;
 903 }
 904
 905 void FGAIBallistic::setHitchVelocity(double dt) {
 906     //calculate the distance from the previous hitch position
 907     SGVec3d carthitchPos = getCartHitchPos();
 908     SGVec3d diff = carthitchPos - _oldcarthitchPos;
 909
 910     double distance = norm(diff);
 911
 912     //calculate speed knots
 913     speed = (distance/dt) * SG_MPS_TO_KT;
 914
 915     //now calulate the angle between the old and current hitch positions (degrees)
 916     double angle = 0;
 917     double daltM = hitchpos.getElevationM() - oldhitchpos.getElevationM();
 918
 919     if (fabs(distance) < SGLimits<float>::min()) {
 920         angle = 0;
 921     } else {
 922         double sAngle = daltM/distance;
 923         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 924         angle = SGMiscd::rad2deg(asin(sAngle));
 925     }
 926
 927     _elevation = angle;
 928
 929     //calculate the bearing of the new hitch position from the old
 930     double az1, az2, dist;
 931
 932     geo_inverse_wgs_84(oldhitchpos, hitchpos, &az1, &az2, &dist);
 933
 934     _azimuth = az1;
 935
 936     // and finally store the new values
 937     _oldcarthitchPos = carthitchPos;
 938     oldhitchpos = hitchpos;
 939 }
 940
 941 double FGAIBallistic::getElevLoadToHitch() const {
 942     // now the angle, positive angles are upwards
 943     double distance = getDistanceLoadToHitch() * SG_FEET_TO_METER;
 944     double angle = 0;
 945     double daltM = hitchpos.getElevationM() - pos.getElevationM();
 946
 947     if (fabs(distance) < SGLimits<float>::min()) {
 948         angle = 0;
 949     } else {
 950         double sAngle = daltM/distance;
 951         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
 952         angle = SGMiscd::rad2deg(asin(sAngle));
 953     }
 954
 955     return angle;
 956 }
 957
 958 double FGAIBallistic::getBearingLoadToHitch() const {
 959     //calculate the bearing and range of the second pos from the first
 960     double az1, az2, distance;
 961
 962     geo_inverse_wgs_84(pos, hitchpos, &az1, &az2, &distance);
 963
 964     return az1;
 965 }
 966
 967 double FGAIBallistic::getRelBrgHitchToUser() const {
 968     //calculate the relative bearing
 969     double az1, az2, distance;
 970
 971     geo_inverse_wgs_84(hitchpos, userpos, &az1, &az2, &distance);
 972
 973     double rel_brg = az1 - hdg;
 974
 975     if (rel_brg > 180)
 976         rel_brg -= 360;
 977
 978     return rel_brg;
 979 }
 980
 981 double FGAIBallistic::getElevHitchToUser() const {
 982
 983     //calculate the distance from the user position
 984     SGVec3d carthitchPos = getCartHitchPos();
 985     SGVec3d cartuserPos = getCartUserPos();
 986
 987     SGVec3d diff = cartuserPos - carthitchPos;
 988
 989     double distance = norm(diff);
 990     double angle = 0;
 991
 992     double daltM = userpos.getElevationM() - hitchpos.getElevationM();
 993
 994     // now the angle, positive angles are upwards
 995     if (fabs(distance) < SGLimits<float>::min()) {
 996         angle = 0;
 997     } else {
 998         double sAngle = daltM/distance;
 999         sAngle = SGMiscd::min(1, SGMiscd::max(-1, sAngle));
1000         angle = SGMiscd::rad2deg(asin(sAngle));
1001     }
1002
1003     return angle;
1004 }
1005
1006 void FGAIBallistic::setTgtOffsets(double dt, double coeff){
1007     double c = dt / (coeff + dt);
1008
1009     _x_offset = (_tgt_x_offset * c) + (_x_offset * (1 - c));
1010     _y_offset = (_tgt_y_offset * c) + (_y_offset * (1 - c));
1011     _z_offset = (_tgt_z_offset * c) + (_z_offset * (1 - c));
1012 }
1013
1014 void FGAIBallistic::formateToAC(double dt){
1015
1016     setTgtOffsets(dt, 25);
1017     setHitchPos();
1018     setHitchVelocity(dt);
1019
1020     // elapsed time has a random initialisation so that each
1021     // wingman moves differently
1022     _elapsed_time += dt;
1023
1024     // we derive a sine based factor to give us smoothly
1025     // varying error between -1 and 1
1026     double factor  = sin(SGMiscd::deg2rad(_elapsed_time * 10));
1027     double r_angle = 5 * factor;
1028     double p_angle = 2.5 * factor;
1029     double h_angle = 5 * factor;
1030     double h_feet  = 3 * factor;
1031
1032     pos.setLatitudeDeg(hitchpos.getLatitudeDeg());
1033     pos.setLongitudeDeg(hitchpos.getLongitudeDeg());
1034
1035     if (getHtAGL()){
1036
1037         if(_ht_agl_ft <= 10) {
1038             _height = userpos.getElevationFt();
1039         } else if (_ht_agl_ft > 10 && _ht_agl_ft <= 150 ) {
1040             setHt(userpos.getElevationFt(), dt, 1.0);
1041         } else if (_ht_agl_ft > 150 && _ht_agl_ft <= 250) {
1042             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.75);
1043         } else
1044             setHt(hitchpos.getElevationFt()+ h_feet, dt, 0.5);
1045
1046         pos.setElevationFt(_height);
1047     }
1048
1049     // these calculations are unreliable at slow speeds
1050     if(speed >= 10) {
1051         setHdg(_azimuth + h_angle, dt, 0.9);
1052         setPch(_elevation + p_angle + _pitch_offset, dt, 0.9);
1053
1054         if (roll <= 115 && roll >= -115)
1055             setBnk(manager->get_user_roll() + r_angle + _roll_offset, dt, 0.5);
1056         else
1057             roll = manager->get_user_roll() + r_angle + _roll_offset;
1058
1059     } else {
1060         setHdg(manager->get_user_heading(), dt, 0.9);
1061         setPch(manager->get_user_pitch() + _pitch_offset, dt, 0.9);
1062         setBnk(manager->get_user_roll() + _roll_offset, dt, 0.9);
1063     }
1064
1065     setSpeed(speed);
1066 }
1067 // end AIBallistic