src/FDM/YASim/Hitch.cpp

   1 #include "Math.hpp"
   2 #include "BodyEnvironment.hpp"
   3 #include "RigidBody.hpp"
   4 #include <string.h>
   5 #include <sstream>
   6
   7
   8
   9 #include "Hitch.hpp"
  10 namespace yasim {
  11 Hitch::Hitch(const char *name)
  12 {
  13     if (fgGetNode("/sim/hitches", true))
  14         _node = fgGetNode("/sim/hitches", true)->getNode(name, true);
  15     else _node = 0;
  16     int i;
  17     for(i=0; i<3; i++)
  18         _pos[i] = _force[i] = _winchPos[i] = _mp_lpos[i]=_towEndForce[i]=_mp_force[i]=0;
  19     for(i=0; i<2; i++)
  20         _global_ground[i] = 0;
  21     _global_ground[2] = 1;
  22     _global_ground[3] = -1e5;
  23     _forceMagnitude=0;
  24     _open=true;
  25     _oldOpen=_open;
  26     _towLength=60;
  27     _towElasticConstant=1e5;
  28     _towBrakeForce=100000;
  29     _towWeightPerM=1;
  30     _winchMaxSpeed=40;
  31     _winchRelSpeed=0;
  32     _winchInitialTowLength=1000;
  33     _winchPower=100000;
  34     _winchMaxForce=10000;
  35     _winchActualForce=0;
  36     _winchMaxTowLength=1000;
  37     _winchMinTowLength=0;
  38     _dist=0;
  39     _towEndIsConnectedToProperty=false;
  40     _towEndNode=0;
  41     _nodeIsMultiplayer=false;
  42     _nodeIsAiAircraft=false;
  43     _forceIsCalculatedByMaster=false;
  44     _nodeID=0;
  45     //_ai_MP_callsign=0;
  46     _height_above_ground=0;
  47     _winch_height_above_ground=0;
  48     _loPosFrac=0;
  49     _lowest_tow_height=0;
  50     _state=new State;
  51     _displayed_len_lower_dist_message=false;
  52     _last_wish=true;
  53     _isSlave=false;
  54     _mpAutoConnectPeriod=0;
  55     _timeToNextAutoConnectTry=0;
  56     _timeToNextReConnectTry=10;
  57     _speed_in_tow_direction=0;
  58     _mp_time_lag=1;
  59     _mp_last_reported_dist=0;
  60     _mp_last_reported_v=0;
  61     _mp_is_slave=false;
  62     _mp_open_last_state=false;
  63     _timeLagCorrectedDist=0;
  64     if (_node)
  65     {
  66         _node->tie("tow/length",SGRawValuePointer<float>(&_towLength));
  67         _node->tie("tow/elastic-constant",SGRawValuePointer<float>(&_towElasticConstant));
  68         _node->tie("tow/weight-per-m-kg-m",SGRawValuePointer<float>(&_towWeightPerM));
  69         _node->tie("tow/brake-force",SGRawValuePointer<float>(&_towBrakeForce));
  70         _node->tie("winch/max-speed-m-s",SGRawValuePointer<float>(&_winchMaxSpeed));
  71         _node->tie("winch/rel-speed",SGRawValuePointer<float>(&_winchRelSpeed));
  72         _node->tie("winch/initial-tow-length-m",SGRawValuePointer<float>(&_winchInitialTowLength));
  73         _node->tie("winch/min-tow-length-m",SGRawValuePointer<float>(&_winchMinTowLength));
  74         _node->tie("winch/max-tow-length-m",SGRawValuePointer<float>(&_winchMaxTowLength));
  75         _node->tie("winch/global-pos-x",SGRawValuePointer<double>(&_winchPos[0]));
  76         _node->tie("winch/global-pos-y",SGRawValuePointer<double>(&_winchPos[1]));
  77         _node->tie("winch/global-pos-z",SGRawValuePointer<double>(&_winchPos[2]));
  78         _node->tie("winch/max-power",SGRawValuePointer<float>(&_winchPower));
  79         _node->tie("winch/max-force",SGRawValuePointer<float>(&_winchMaxForce));
  80         _node->tie("winch/actual-force",SGRawValuePointer<float>(&_winchActualForce));
  81         _node->tie("tow/end-force-x",SGRawValuePointer<float>(&_reportTowEndForce[0]));
  82         _node->tie("tow/end-force-y",SGRawValuePointer<float>(&_reportTowEndForce[1]));
  83         _node->tie("tow/end-force-z",SGRawValuePointer<float>(&_reportTowEndForce[2]));
  84         _node->tie("force",SGRawValuePointer<float>(&_forceMagnitude));
  85         _node->tie("open",SGRawValuePointer<bool>(&_open));
  86         _node->tie("force-is-calculated-by-other",SGRawValuePointer<bool>(&_forceIsCalculatedByMaster));
  87         _node->tie("local-pos-x",SGRawValuePointer<float>(&_pos[0]));
  88         _node->tie("local-pos-y",SGRawValuePointer<float>(&_pos[1]));
  89         _node->tie("local-pos-z",SGRawValuePointer<float>(&_pos[2]));
  90         _node->tie("tow/dist",SGRawValuePointer<float>(&_dist));
  91         _node->tie("tow/dist-time-lag-corrected",SGRawValuePointer<float>(&_timeLagCorrectedDist));
  92         _node->tie("tow/connected-to-property-node",SGRawValuePointer<bool>(&_towEndIsConnectedToProperty));
  93         _node->tie("tow/connected-to-mp-node",SGRawValuePointer<bool>(&_nodeIsMultiplayer));
  94         _node->tie("tow/connected-to-ai-node",SGRawValuePointer<bool>(&_nodeIsAiAircraft));
  95         _node->tie("tow/connected-to-ai-or-mp-id",SGRawValuePointer<int>(&_nodeID));
  96         _node->tie("debug/hitch-height-above-ground",SGRawValuePointer<float>(&_height_above_ground));
  97         _node->tie("debug/tow-end-height-above-ground",SGRawValuePointer<float>(&_winch_height_above_ground));
  98         _node->tie("debug/tow-rel-lo-pos",SGRawValuePointer<float>(&_loPosFrac));
  99         _node->tie("debug/tow-lowest-pos-height",SGRawValuePointer<float>(&_lowest_tow_height));
 100         _node->tie("is-slave",SGRawValuePointer<bool>(&_isSlave));
 101         _node->tie("speed-in-tow-direction",SGRawValuePointer<float>(&_speed_in_tow_direction));
 102         _node->tie("mp-auto-connect-period",SGRawValuePointer<float>(&_mpAutoConnectPeriod));
 103         _node->tie("mp-time-lag",SGRawValuePointer<float>(&_mp_time_lag));
 104         _node->setStringValue("tow/node","");
 105         _node->setStringValue("tow/connected-to-ai-or-mp-callsign");
 106         _node->setBoolValue("broken",false);
 107     }
 108 }
 109
 110 Hitch::~Hitch()
 111 {
 112     if (_node)
 113     {
 114         _node->untie("tow/length");
 115         _node->untie("tow/elastic-constant");
 116         _node->untie("tow/weight-per-m-kg-m");
 117         _node->untie("tow/brake-force");
 118         _node->untie("winch/max-speed-m-s");
 119         _node->untie("winch/rel-speed");
 120         _node->untie("winch/initial-tow-length-m");
 121         _node->untie("winch/min-tow-length-m");
 122         _node->untie("winch/max-tow-length-m");
 123         _node->untie("winch/global-pos-x");
 124         _node->untie("winch/global-pos-y");
 125         _node->untie("winch/global-pos-z");
 126         _node->untie("winch/max-power");
 127         _node->untie("winch/max-force");
 128         _node->untie("winch/actual-force");
 129         _node->untie("tow/end-force-x");
 130         _node->untie("tow/end-force-y");
 131         _node->untie("tow/end-force-z");
 132         _node->untie("force");
 133         _node->untie("open");
 134         _node->untie("force-is-calculated-by-other");
 135         _node->untie("local-pos-x");
 136         _node->untie("local-pos-y");
 137         _node->untie("local-pos-z");
 138         _node->untie("tow/dist");
 139         _node->untie("tow/dist-time-lag-corrected");
 140         _node->untie("tow/connected-to-property-node");
 141         _node->untie("tow/connected-to-mp-node");
 142         _node->untie("tow/connected-to-ai-node");
 143         _node->untie("tow/connected-to-ai-or-mp-id");
 144         _node->untie("debug/hitch-height-above-ground");
 145         _node->untie("debug/tow-end-height-above-ground");
 146         _node->untie("debug/tow-rel-lo-pos");
 147         _node->untie("debug/tow-lowest-pos-height");
 148         _node->untie("is-slave");
 149         _node->untie("speed-in-tow-direction");
 150         _node->untie("mp-auto-connect-period");
 151         _node->untie("mp-time-lag");
 152     }
 153     delete _state;
 154 }
 155
 156 void Hitch::setPosition(float* position)
 157 {
 158     int i;
 159     for(i=0; i<3; i++) _pos[i] = position[i];
 160 }
 161
 162 void Hitch::setTowLength(float length)
 163 {
 164     _towLength = length;
 165 }
 166
 167 void Hitch::setOpen(bool isOpen)
 168 {
 169    //test if we already processed this before
 170     //without this test a binded property could
 171     //try to close the Hitch every run
 172     //it will close, if we are near the end
 173     //e.g. if we are flying over the parked
 174     //tow-aircraft....
 175     if (isOpen==_last_wish)
 176         return;
 177     _last_wish=isOpen;
 178     _open=isOpen;
 179 }
 180
 181 void Hitch::setTowElasticConstant(float sc)
 182 {
 183     _towElasticConstant=sc;
 184 }
 185
 186 void Hitch::setTowBreakForce(float bf)
 187 {
 188     _towBrakeForce=bf;
 189 }
 190
 191 void Hitch::setWinchMaxForce(float f)
 192 {
 193     _winchMaxForce=f;
 194 }
 195
 196 void Hitch::setTowWeightPerM(float rw)
 197 {
 198     _towWeightPerM=rw;
 199 }
 200
 201 void Hitch::setWinchMaxSpeed(float mws)
 202 {
 203     _winchMaxSpeed=mws;
 204 }
 205
 206 void Hitch::setWinchRelSpeed(float rws)
 207 {
 208     _winchRelSpeed=rws;
 209 }
 210
 211 void Hitch::setWinchPosition(double *winchPosition)//in global coordinates!
 212 {
 213     for (int i=0; i<3;i++)
 214         _winchPos[i]=winchPosition[i];
 215 }
 216
 217 void Hitch::setMpAutoConnectPeriod(float dt)
 218 {
 219     _mpAutoConnectPeriod=dt;
 220 }
 221
 222 void Hitch::setForceIsCalculatedByOther(bool b)
 223 {
 224     _forceIsCalculatedByMaster=b;
 225 }
 226
 227 std::string Hitch::getConnectedPropertyNode() const
 228 {
 229     if (_towEndNode)
 230         return _towEndNode->getDisplayName();
 231     else
 232         return std::string("");
 233 }
 234
 235 void Hitch::setConnectedPropertyNode(const char *nodename)
 236 {
 237     _towEndNode=fgGetNode(nodename,false);
 238 }
 239
 240 void Hitch::setWinchPositionAuto(bool doit)
 241 {
 242     static bool lastState=false;
 243     if(!_state)
 244         return;
 245     if (!doit)
 246     {
 247         lastState=false;
 248         return;
 249     }
 250     if(lastState)
 251         return;
 252     lastState=true;
 253     float lWinchPos[3];
 254     // The ground plane transformed to the local frame.
 255     float ground[4];
 256     _state->planeGlobalToLocal(_global_ground, ground);
 257
 258     float help[3];
 259     //find a normalized vector pointing forward parallel to the ground
 260     help[0]=0;
 261     help[1]=1;
 262     help[2]=0;
 263     Math::cross3(ground,help,help);
 264     //multiplay by initial tow length;
 265     //reduced by 1m to be able to close the
 266     //hitch either if the glider slips backwards a bit
 267     Math::mul3((_winchInitialTowLength-1.),help,help);
 268     //add to the actual pos
 269     Math::add3(_pos,help,lWinchPos);
 270     //put it onto the ground plane
 271     Math::mul3(ground[3],ground,help);
 272     Math::add3(lWinchPos,help,lWinchPos);
 273
 274     _state->posLocalToGlobal(lWinchPos,_winchPos);
 275     _towLength=_winchInitialTowLength;
 276     fgSetString("/sim/messages/pilot", "Connected to winch!");
 277     _open=false;
 278
 279     _node->setBoolValue("broken",false);
 280
 281     //set the dist value (if not, the hitch would open in the next calcforce run
 282     float delta[3];
 283     Math::sub3(lWinchPos,_pos,delta);
 284     _dist=Math::mag3(delta);
 285 }
 286
 287 void Hitch::findBestAIObject(bool doit,bool running_as_autoconnect)
 288 {
 289     static bool lastState=false;
 290     if(!_state)
 291         return;
 292     if (!running_as_autoconnect)
 293     {
 294         //if this function is binded to an input, it will be called every frame as long as the key is pressed.
 295         //therefore wait for a key-release before running it again.
 296         if (!doit)
 297         {
 298             lastState=false;
 299             return;
 300         }
 301         if(lastState)
 302             return;
 303         lastState=true;
 304     }
 305     double gpos[3];
 306     _state->posLocalToGlobal(_pos,gpos);
 307     double bestdist=_towLength*_towLength;//squared!
 308     _towEndIsConnectedToProperty=false;
 309     SGPropertyNode * ainode = fgGetNode("/ai/models",false);
 310     if(!ainode) return;
 311     char myCallsign[256]="***********";
 312     if (running_as_autoconnect)
 313     {
 314         //get own callsign
 315         SGPropertyNode *cs=fgGetNode("/sim/multiplay/callsign",false);
 316         if (cs)
 317         {
 318             strncpy(myCallsign,cs->getStringValue(),256);
 319             myCallsign[255]=0;
 320         }
 321         //reset tow length for search radius. Lentgh will be later copied from master
 322         _towLength=_winchInitialTowLength;
 323     }
 324     bool found=false;
 325     vector <SGPropertyNode_ptr> nodes;//<SGPropertyNode_ptr>
 326     for (int i=0;i<ainode->nChildren();i++)
 327     {
 328         SGPropertyNode * n=ainode->getChild(i);
 329         _nodeIsMultiplayer = strncmp("multiplayer",n->getName(),11)==0;
 330         _nodeIsAiAircraft = strncmp("aircraft",n->getName(),8)==0;
 331         if (!(_nodeIsMultiplayer || _nodeIsAiAircraft))
 332             continue;
 333         if (running_as_autoconnect)
 334         {
 335             if (!_nodeIsMultiplayer)
 336                 continue;
 337             if(n->getBoolValue("sim/hitches/aerotow/open",true)) continue;
 338             if(strncmp(myCallsign,n->getStringValue("sim/hitches/aerotow/tow/connected-to-ai-or-mp-callsign"),255)!=0)
 339                 continue;
 340         }
 341         double pos[3];
 342         pos[0]=n->getDoubleValue("position/global-x",0);
 343         pos[1]=n->getDoubleValue("position/global-y",0);
 344         pos[2]=n->getDoubleValue("position/global-z",0);
 345         double dist=0;
 346         for (int j=0;j<3;j++)
 347             dist+=(pos[j]-gpos[j])*(pos[j]-gpos[j]);
 348         if (dist<bestdist)
 349         {
 350             bestdist=dist;
 351             _towEndNode=n;
 352             _towEndIsConnectedToProperty=true;
 353             //_node->setStringValue("tow/node",n->getPath());
 354             _node->setStringValue("tow/node",n->getDisplayName());
 355             _nodeID=n->getIntValue("id",0);
 356             _node->setStringValue("tow/connected-to-ai-or-mp-callsign",n->getStringValue("callsign"));
 357             _open=false;
 358             found = true;
 359         }
 360     }
 361     if (found)
 362     {
 363         if (!running_as_autoconnect)
 364         {
 365             std::stringstream message;
 366             message<<_node->getStringValue("tow/connected-to-ai-or-mp-callsign")
 367                     <<", I am on your hook, distance "<<Math::sqrt(bestdist)<<" meter.";
 368             fgSetString("/sim/messages/pilot", message.str().c_str());
 369         }
 370         else
 371         {
 372             std::stringstream message;
 373             message<<_node->getStringValue("tow/connected-to-ai-or-mp-callsign")
 374                 <<": I am on your hook, distance "<<Math::sqrt(bestdist)<<" meter.";
 375             fgSetString("/sim/messages/ai-plane", message.str().c_str());
 376         }
 377         if (running_as_autoconnect)
 378             _isSlave=true;
 379         //set the dist value to some value below the tow lentgh (if not, the hitch
 380         //would open in the next calc force run
 381         _dist=_towLength*0.5;
 382         _mp_open_last_state=true;
 383     }
 384     else
 385         if (!running_as_autoconnect)
 386         {
 387             fgSetString("/sim/messages/atc", "Sorry, no aircraft for aerotow!");
 388         }
 389 }
 390
 391 void Hitch::setWinchInitialTowLength(float length)
 392 {
 393     _winchInitialTowLength=length;
 394 }
 395
 396 void Hitch::setWinchPower(float power)
 397 {
 398     _winchPower=power;
 399 }
 400
 401 void Hitch::setWinchMaxTowLength(float length)
 402 {
 403     _winchMaxTowLength=length;
 404 }
 405
 406 void Hitch::setWinchMinTowLength(float length)
 407 {
 408     _winchMinTowLength=length;
 409 }
 410
 411 void Hitch::setGlobalGround(double *global_ground, float *global_vel)
 412 {
 413     int i;
 414     for(i=0; i<4; i++) _global_ground[i] = global_ground[i];
 415     for(i=0; i<3; i++) _global_vel[i] = global_vel[i];
 416 }
 417
 418 void Hitch::getPosition(float* out)
 419 {
 420     int i;
 421     for(i=0; i<3; i++) out[i] = _pos[i];
 422 }
 423
 424 float Hitch::getTowLength(void)
 425 {
 426     return _towLength;
 427 }
 428
 429 void Hitch::calcForce(Ground *g_cb, RigidBody* body, State* s)
 430 {
 431     float lWinchPos[3],delta[3],deltaN[3];
 432     *_state=*s;
 433     s->posGlobalToLocal(_winchPos,lWinchPos);
 434     Math::sub3(lWinchPos,_pos,delta);
 435     if(!_towEndIsConnectedToProperty)
 436         _dist=Math::mag3(delta);
 437     else
 438         _dist=Math::mag3(lWinchPos); //use the aircraft center as reference for distance calculation
 439                                   //this position is transferred to the MP-Aircraft.
 440                                   //With this trick, both player in aerotow get the same length
 441     Math::unit3(delta,deltaN);
 442     float lvel[3];
 443     s->velGlobalToLocal(s->v,lvel);
 444     _speed_in_tow_direction=Math::dot3(lvel,deltaN);
 445     if (_towEndIsConnectedToProperty && _nodeIsMultiplayer)
 446     {
 447         float mp_delta_dist_due_to_time_lag=0.5*_mp_time_lag*(-_mp_v+_speed_in_tow_direction);
 448         _timeLagCorrectedDist=_dist+mp_delta_dist_due_to_time_lag;
 449         if(_forceIsCalculatedByMaster && !_open)
 450         {
 451             s->velGlobalToLocal(_mp_force,_force);
 452             return;
 453         }
 454     }
 455     else
 456         _timeLagCorrectedDist=_dist;
 457     if (_open)
 458     {
 459         _force[0]=_force[1]=_force[2]=0;
 460         return;
 461     }
 462     if(_dist>_towLength)
 463         if(_towLength>1e-3)
 464             _forceMagnitude=(_dist-_towLength)/_towLength*_towElasticConstant;
 465         else
 466             _forceMagnitude=2*_towBrakeForce;
 467     else
 468         _forceMagnitude=0;
 469     if(_forceMagnitude>=_towBrakeForce)
 470     {
 471         _forceMagnitude=0;
 472         _open=true;
 473         _node->setBoolValue("broken",true);
 474         _force[0]=_force[1]=_force[2]=0;
 475         _towEndForce[0]=_towEndForce[1]=_towEndForce[2]=0;
 476         _reportTowEndForce[0]=_reportTowEndForce[1]=_reportTowEndForce[2]=0;
 477         return;
 478     }
 479     Math::mul3(_forceMagnitude,deltaN,_force);
 480     Math::mul3(-1.,_force,_towEndForce);
 481     _winchActualForce=_forceMagnitude; //missing: gravity on this end and friction
 482     //Add the gravitiy of the rope.
 483     //calculate some numbers:
 484     float grav_force=_towWeightPerM*_towLength*9.81;
 485     //the length of the gravity-expanded row:
 486     float leng=_towLength+grav_force*_towLength/_towElasticConstant;
 487     // The ground plane transformed to the local frame.
 488     float ground[4];
 489     s->planeGlobalToLocal(_global_ground, ground);
 490
 491     // The velocity of the contact patch transformed to local coordinates.
 492     //float glvel[3];
 493     //s->velGlobalToLocal(_global_vel, glvel);
 494
 495     _height_above_ground = ground[3] - Math::dot3(_pos, ground);
 496
 497     //the same for the winch-pos (the pos of the tow end)
 498     _winch_height_above_ground = ground[3] - Math::dot3(lWinchPos, ground);
 499
 500     //the frac of the grav force acting on _pos:
 501     float grav_frac=0.5*(1+(_height_above_ground-_winch_height_above_ground)/leng);
 502     grav_frac=Math::clamp(grav_frac,0,1);
 503     float grav_frac_tow_end=1-grav_frac;
 504     //reduce grav_frac, if the tow has ground contact.
 505     if (_height_above_ground<leng) //if not, the tow can not be on ground
 506     {
 507         float fa[3],fb[3],fg[3];
 508         //the grav force an the hitch position:
 509         Math::mul3(-grav_frac*grav_force,ground,fg);
 510         //the total force on hitch postion:
 511         Math::add3(fg,_force,fa);
 512         //the grav force an the tow end position:
 513         Math::mul3(-(1-grav_frac)*grav_force,ground,fg);
 514         //the total force on tow end postion:
 515         //note: sub: _force on tow-end is negative of force on hitch postion
 516         Math::sub3(fg,_force,fb);
 517         float fa_=Math::mag3(fa);
 518         float fb_=Math::mag3(fb);
 519         float stretchedTowLen;
 520         stretchedTowLen=_towLength*(1.+(fa_+fb_)/(2*_towElasticConstant));
 521         //the relative position of the lowest postion of the tow:
 522         if ((fa_+fb_)>1e-3)
 523             _loPosFrac=fa_/(fa_+fb_);
 524         else
 525             _loPosFrac=0.5;
 526         //dist to tow-end parallel to ground
 527         float ground_dist;
 528         float help[3];
 529         //Math::cross3(delta,ground,help);//as long as we calculate the dist without _pos, od it with lWinchpos, the dist to our center....
 530         Math::cross3(lWinchPos,ground,help);
 531         ground_dist=Math::mag3(help);
 532         //height of lowest tow pos (relative to _pos)
 533         _lowest_tow_height=_loPosFrac*Math::sqrt(Math::abs(stretchedTowLen*stretchedTowLen-ground_dist*ground_dist));
 534         if (_height_above_ground<_lowest_tow_height)
 535         {
 536             if (_height_above_ground>1e-3)
 537                 grav_frac*=_height_above_ground/_lowest_tow_height;
 538             else
 539                 grav_frac=0;
 540         }
 541         if (_winch_height_above_ground<(_lowest_tow_height-_height_above_ground+_winch_height_above_ground))
 542         {
 543             if (_winch_height_above_ground>1e-3)
 544                 grav_frac_tow_end*=_winch_height_above_ground/
 545                     (_lowest_tow_height-_height_above_ground+_winch_height_above_ground);
 546             else
 547                 grav_frac_tow_end=0;
 548         }
 549     }
 550     else _lowest_tow_height=_loPosFrac=-1; //for debug output
 551     float grav_force_v[3];
 552     Math::mul3(grav_frac*grav_force,ground,grav_force_v);
 553     Math::add3(grav_force_v,_force,_force);
 554     _forceMagnitude=Math::mag3(_force);
 555     //the same for the tow end:
 556     Math::mul3(grav_frac_tow_end*grav_force,ground,grav_force_v);
 557     Math::add3(grav_force_v,_towEndForce,_towEndForce);
 558     s->velLocalToGlobal(_towEndForce,_towEndForce);
 559
 560     if(_forceMagnitude>=_towBrakeForce)
 561     {
 562         _forceMagnitude=0;
 563         _open=true;
 564         _node->setBoolValue("broken",true);
 565         _force[0]=_force[1]=_force[2]=0;
 566         _towEndForce[0]=_towEndForce[1]=_towEndForce[2]=0;
 567     }
 568
 569
 570 }
 571
 572 // Computed values: total force
 573 void Hitch::getForce(float* force, float* off)
 574 {
 575     Math::set3(_force, force);
 576     Math::set3(_pos, off);
 577 }
 578
 579 void Hitch::integrate (float dt)
 580 {
 581     //check if hitch has opened or closed, if yes: message
 582     if (_open !=_oldOpen)
 583     {
 584         if (_oldOpen)
 585         {
 586             if (_dist>_towLength*1.00001)
 587             {
 588                 std::stringstream message;
 589                 message<<"Could not lock hitch (tow length is insufficient) on hitch "
 590                        <<_node->getName()<<" "<<_node->getIndex()<<"!";
 591                 fgSetString("/sim/messages/pilot", message.str().c_str());
 592                 _open=true;
 593                 return;
 594             }
 595             _node->setBoolValue("broken",false);
 596         }
 597         std::stringstream message;
 598         if (_node->getBoolValue("broken",false)&&_open)
 599             message<<"Oh no, the tow is broken";
 600         else
 601             message<<(_open?"Opened hitch ":"Locked hitch ")<<_node->getName()<<" "<<_node->getIndex()<<"!";
 602         fgSetString("/sim/messages/pilot", message.str().c_str());
 603         _oldOpen=_open;
 604     }
 605
 606     //check, if tow end should be searched in all MP-aircrafts
 607     if(_open && _mpAutoConnectPeriod)
 608     {
 609         _isSlave=false;
 610         _timeToNextAutoConnectTry-=dt;
 611         if ((_timeToNextAutoConnectTry>_mpAutoConnectPeriod) || (_timeToNextAutoConnectTry<0))
 612         {
 613             _timeToNextAutoConnectTry=_mpAutoConnectPeriod;
 614             //search for MP-Aircraft, which is towed with us
 615             findBestAIObject(true,true);
 616         }
 617     }
 618     //check, if tow end can be modified by property, if yes: update
 619     if(_towEndIsConnectedToProperty)
 620     {
 621         if (_node)
 622         {
 623             //_towEndNode=fgGetNode(_node->getStringValue("tow/node"), false);
 624             char towNode[256];
 625             strncpy(towNode,_node->getStringValue("tow/node"),256);
 626             towNode[255]=0;
 627             _towEndNode=fgGetNode("ai/models")->getNode(towNode, false);
 628             //AI and multiplayer objects seem to change node?
 629             //Check if we have the right one by callsign
 630             if (_nodeIsMultiplayer || _nodeIsAiAircraft)
 631             {
 632                 char MPcallsign[256]="";
 633                 const char *MPc;
 634                 MPc=_node->getStringValue("tow/connected-to-ai-or-mp-callsign");
 635                 if (MPc)
 636                 {
 637                     strncpy(MPcallsign,MPc,256);
 638                     MPcallsign[255]=0;
 639                 }
 640                 if (((_towEndNode)&&(strncmp(_towEndNode->getStringValue("callsign"),MPcallsign,255)!=0))||!_towEndNode)
 641                 {
 642                     _timeToNextReConnectTry-=dt;
 643                     if((_timeToNextReConnectTry<0)||(_timeToNextReConnectTry>10))
 644                     {
 645                         _timeToNextReConnectTry=10;
 646                         SGPropertyNode * ainode = fgGetNode("/ai/models",false);
 647                         if(ainode)
 648                         {
 649                             for (int i=0;i<ainode->nChildren();i++)
 650                             {
 651                                 SGPropertyNode * n=ainode->getChild(i);
 652                                 if(_nodeIsMultiplayer?strncmp("multiplayer",n->getName(),11)==0:strncmp("aircraft",n->getName(),8))
 653                                     if (strcmp(n->getStringValue("callsign"),MPcallsign)==0)//found
 654                                     {
 655                                         _towEndNode=n;
 656                                         //_node->setStringValue("tow/node",n->getPath());
 657                                         _node->setStringValue("tow/node",n->getDisplayName());
 658                                     }
 659                             }
 660                         }
 661                     }
 662                 }
 663             }
 664             if(_towEndNode)
 665             {
 666                 _winchPos[0]=_towEndNode->getDoubleValue("position/global-x",_winchPos[0]);
 667                 _winchPos[1]=_towEndNode->getDoubleValue("position/global-y",_winchPos[1]);
 668                 _winchPos[2]=_towEndNode->getDoubleValue("position/global-z",_winchPos[2]);
 669                 _mp_lpos[0]=_towEndNode->getFloatValue("sim/hitches/aerotow/local-pos-x",0);
 670                 _mp_lpos[1]=_towEndNode->getFloatValue("sim/hitches/aerotow/local-pos-y",0);
 671                 _mp_lpos[2]=_towEndNode->getFloatValue("sim/hitches/aerotow/local-pos-z",0);
 672                 _mp_dist=_towEndNode->getFloatValue("sim/hitches/aerotow/tow/dist");
 673                 _mp_v=_towEndNode->getFloatValue("sim/hitches/aerotow/speed-in-tow-direction");
 674                 _mp_force[0]=_towEndNode->getFloatValue("sim/hitches/aerotow/tow/end-force-x",0);
 675                 _mp_force[1]=_towEndNode->getFloatValue("sim/hitches/aerotow/tow/end-force-y",0);
 676                 _mp_force[2]=_towEndNode->getFloatValue("sim/hitches/aerotow/tow/end-force-z",0);
 677
 678                 if(_isSlave)
 679                 {
 680 #define gf(a,b) a=_towEndNode->getFloatValue(b,a)
 681 #define gb(a,b) a=_towEndNode->getBoolValue(b,a)
 682                     gf(_towLength,"sim/hitches/aerotow/tow/length");
 683                     gf(_towElasticConstant,"sim/hitches/aerotow/tow/elastic-constant");
 684                     gf(_towWeightPerM,"sim/hitches/aerotow/tow/weight-per-m-kg-m");
 685                     gf(_towBrakeForce,"sim/hitches/aerotow/brake-force");
 686                     gb(_open,"sim/hitches/aerotow/open");
 687                     gb(_mp_is_slave,"sim/hitches/aerotow/is-slave");
 688 #undef gf
 689 #undef gb
 690                     if (_mp_is_slave) _isSlave=false; //someone should be master
 691                 }
 692                 else
 693                 {
 694                     //check if other has opened hitch, but is neccessary, that it was closed before
 695                     bool mp_open=_towEndNode->getBoolValue("sim/hitches/aerotow/open",_mp_open_last_state);
 696                     if (mp_open != _mp_open_last_state) //state has changed
 697                     {
 698                         _mp_open_last_state=mp_open; //store that value
 699                         if(!_open)
 700                         {
 701                             if(mp_open)
 702                             {
 703                                 _oldOpen=_open=true;
 704                                 std::stringstream message;
 705                                 message<<_node->getStringValue("tow/connected-to-ai-or-mp-callsign")
 706                                     <<": I have released the tow!";
 707                                 fgSetString("/sim/messages/ai-plane", message.str().c_str());
 708                             }
 709                         }
 710                     }
 711                 }
 712                 //try to calculate the time lag
 713                 if ((_mp_last_reported_dist!=_mp_dist)||(_mp_last_reported_v!=_mp_v)) //new data;
 714                 {
 715                     _mp_last_reported_dist=_mp_dist;
 716                     _mp_last_reported_v=_mp_v;
 717                     float total_v=-_mp_v+_speed_in_tow_direction;//mp has opposite tow direction
 718                     float abs_v=Math::abs(total_v);
 719                     if (abs_v>0.1)
 720                     {
 721                         float actual_time_lag_guess=(_mp_dist-_dist)/total_v;
 722                         //check, if it sounds ok
 723                         if((actual_time_lag_guess>0)&&(actual_time_lag_guess<5))
 724                         {
 725                             float frac=abs_v*0.01;
 726                             if (frac>0.05) frac=0.05;
 727                             // if we are slow, the guess of the lag can be rather wrong. as faster we are
 728                             // the better the guess. Therefore frac is proportiona to the speed. Clamp it
 729                             // at 5m/s
 730                             _mp_time_lag=(1-frac)*_mp_time_lag+frac*actual_time_lag_guess;
 731                         }
 732                     }
 733                 }
 734             }
 735         }
 736     }
 737     //set the _reported_tow_end_force
 738     Math::set3(_towEndForce,_reportTowEndForce);
 739
 740     if (_open) return;
 741     if (_winchRelSpeed==0) return;
 742     float factor=1,offset=0;
 743     if (_winchActualForce>_winchMaxForce)
 744         offset=-(_winchActualForce-_winchMaxForce)/_winchMaxForce*20;
 745     if (_winchRelSpeed>0.01) // to avoit div by zero
 746     {
 747         float maxForcePowerLimit=_winchPower/(_winchRelSpeed*_winchMaxSpeed);
 748         if (_winchActualForce>maxForcePowerLimit)
 749             factor-=(_winchActualForce-maxForcePowerLimit)/maxForcePowerLimit;
 750     }
 751     _towLength-=dt*(factor*_winchRelSpeed+offset)*_winchMaxSpeed;
 752     if (_towLength<=_winchMinTowLength)
 753     {
 754         if (_winchRelSpeed<0)
 755             _winchRelSpeed=0;
 756         _towLength=_winchMinTowLength;
 757         return;
 758     }
 759     if (_towLength>=_winchMaxTowLength)
 760     {
 761         if (_winchRelSpeed<0)
 762             _winchRelSpeed=0;
 763         _towLength=_winchMaxTowLength;
 764         return;
 765     }
 766 }
 767
 768
 769
 770
 771 }; // namespace yasim