src/FDM/YASim/FGFDM.cpp

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3
   4 #include <Main/fg_props.hxx>
   5
   6 #include "Math.hpp"
   7 #include "Jet.hpp"
   8 #include "SimpleJet.hpp"
   9 #include "Gear.hpp"
  10 #include "Hook.hpp"
  11 #include "Launchbar.hpp"
  12 #include "Atmosphere.hpp"
  13 #include "PropEngine.hpp"
  14 #include "Propeller.hpp"
  15 #include "PistonEngine.hpp"
  16 #include "TurbineEngine.hpp"
  17 #include "Rotor.hpp"
  18 #include "Rotorpart.hpp"
  19 #include "Hitch.hpp"
  20
  21 #include "FGFDM.hpp"
  22
  23 namespace yasim {
  24
  25 // Some conversion factors
  26 static const float KTS2MPS = 0.514444444444;
  27 static const float FT2M = 0.3048;
  28 static const float DEG2RAD = 0.0174532925199;
  29 static const float RPM2RAD = 0.10471975512;
  30 static const float LBS2N = 4.44822;
  31 static const float LBS2KG = 0.45359237;
  32 static const float KG2LBS = 2.2046225;
  33 static const float CM2GALS = 264.172037284;
  34 static const float HP2W = 745.700;
  35 static const float INHG2PA = 3386.389;
  36 static const float K2DEGF = 1.8;
  37 static const float K2DEGFOFFSET = -459.4;
  38 static const float CIN2CM = 1.6387064e-5;
  39 static const float YASIM_PI = 3.14159265358979323846;
  40
  41 static const float NM2FTLB = (1/(LBS2N*FT2M));
  42
  43 // Stubs, so that this can be compiled without the FlightGear
  44 // binary.  What's the best way to handle this?
  45
  46 //     float fgGetFloat(char* name, float def) { return 0; }
  47 //     void fgSetFloat(char* name, float val) {}
  48
  49 FGFDM::FGFDM()
  50 {
  51     _vehicle_radius = 0.0f;
  52
  53     _nextEngine = 0;
  54
  55     // Map /controls/flight/elevator to the approach elevator control.  This
  56     // should probably be settable, but there are very few aircraft
  57     // who trim their approaches using things other than elevator.
  58     _airplane.setElevatorControl(parseAxis("/controls/flight/elevator-trim"));
  59
  60     // FIXME: read seed from somewhere?
  61     int seed = 0;
  62     _turb = new Turbulence(10, seed);
  63 }
  64
  65 FGFDM::~FGFDM()
  66 {
  67     int i;
  68     for(i=0; i<_axes.size(); i++) {
  69         AxisRec* a = (AxisRec*)_axes.get(i);
  70         delete[] a->name;
  71         delete a;
  72     }
  73     for(i=0; i<_thrusters.size(); i++) {
  74         EngRec* er = (EngRec*)_thrusters.get(i);
  75         delete[] er->prefix;
  76         delete er->eng;
  77         delete er;
  78     }
  79     for(i=0; i<_weights.size(); i++) {
  80         WeightRec* wr = (WeightRec*)_weights.get(i);
  81         delete[] wr->prop;
  82         delete wr;
  83     }
  84     for(i=0; i<_controlProps.size(); i++)
  85         delete (PropOut*)_controlProps.get(i);
  86     delete _turb;
  87 }
  88
  89 void FGFDM::iterate(float dt)
  90 {
  91     getExternalInput(dt);
  92     _airplane.iterate(dt);
  93
  94     // Do fuel stuff (FIXME: should stash SGPropertyNode objects here)
  95     char buf[256];
  96     for(int i=0; i<_airplane.numThrusters(); i++) {
  97         Thruster* t = _airplane.getThruster(i);
  98
  99         sprintf(buf, "/engines/engine[%d]/out-of-fuel", i);
 100         t->setFuelState(!fgGetBool(buf));
 101
 102         sprintf(buf, "/engines/engine[%d]/fuel-consumed-lbs", i);
 103         double consumed = fgGetDouble(buf) + dt * KG2LBS * t->getFuelFlow();
 104         fgSetDouble(buf, consumed);
 105     }
 106     for(int i=0; i<_airplane.numTanks(); i++) {
 107         sprintf(buf, "/consumables/fuel/tank[%d]/level-lbs", i);
 108         _airplane.setFuel(i, LBS2KG * fgGetFloat(buf));
 109     }
 110     _airplane.calcFuelWeights();
 111
 112     setOutputProperties(dt);
 113 }
 114
 115 Airplane* FGFDM::getAirplane()
 116 {
 117     return &_airplane;
 118 }
 119
 120 void FGFDM::init()
 121 {
 122     // Allows the user to start with something other than full fuel
 123     _airplane.setFuelFraction(fgGetFloat("/sim/fuel-fraction", 1));
 124
 125     // Read out the resulting fuel state
 126     char buf[256];
 127     for(int i=0; i<_airplane.numTanks(); i++) {
 128         sprintf(buf, "/consumables/fuel/tank[%d]/level-lbs", i);
 129         fgSetDouble(buf, _airplane.getFuel(i) * KG2LBS);
 130
 131         double density = _airplane.getFuelDensity(i);
 132         sprintf(buf, "/consumables/fuel/tank[%d]/density-ppg", i);
 133         fgSetDouble(buf, density * (KG2LBS/CM2GALS));
 134
 135         sprintf(buf, "/consumables/fuel/tank[%d]/level-gal_us", i);
 136         fgSetDouble(buf, _airplane.getFuel(i) * CM2GALS / density);
 137
 138         sprintf(buf, "/consumables/fuel/tank[%d]/capacity-gal_us", i);
 139         fgSetDouble(buf, CM2GALS * _airplane.getTankCapacity(i)/density);
 140     }
 141
 142     // This has a nasty habit of being false at startup.  That's not
 143     // good.
 144     fgSetBool("/controls/gear/gear-down", true);
 145
 146     _airplane.getModel()->setTurbulence(_turb);
 147 }
 148
 149 // Not the worlds safest parser.  But it's short & sweet.
 150 void FGFDM::startElement(const char* name, const XMLAttributes &atts)
 151 {
 152     XMLAttributes* a = (XMLAttributes*)&atts;
 153     float v[3];
 154     char buf[64];
 155
 156     if(eq(name, "airplane")) {
 157         _airplane.setWeight(attrf(a, "mass") * LBS2KG);
 158     } else if(eq(name, "approach")) {
 159         float spd = attrf(a, "speed") * KTS2MPS;
 160         float alt = attrf(a, "alt", 0) * FT2M;
 161         float aoa = attrf(a, "aoa", 0) * DEG2RAD;
 162         float gla = attrf(a, "glide-angle", 0) * DEG2RAD;
 163         _airplane.setApproach(spd, alt, aoa, attrf(a, "fuel", 0.2),gla);
 164         _cruiseCurr = false;
 165     } else if(eq(name, "cruise")) {
 166         float spd = attrf(a, "speed") * KTS2MPS;
 167         float alt = attrf(a, "alt") * FT2M;
 168         float gla = attrf(a, "glide-angle", 0) * DEG2RAD;
 169         _airplane.setCruise(spd, alt, attrf(a, "fuel", 0.5),gla);
 170         _cruiseCurr = true;
 171     } else if(eq(name, "solve-weight")) {
 172         int idx = attri(a, "idx");
 173         float wgt = attrf(a, "weight") * LBS2KG;
 174         _airplane.addSolutionWeight(!_cruiseCurr, idx, wgt);
 175     } else if(eq(name, "cockpit")) {
 176         v[0] = attrf(a, "x");
 177         v[1] = attrf(a, "y");
 178         v[2] = attrf(a, "z");
 179         _airplane.setPilotPos(v);
 180     } else if(eq(name, "rotor")) {
 181         _airplane.getModel()->getRotorgear()->addRotor(parseRotor(a, name));
 182     } else if(eq(name, "rotorgear")) {
 183         Rotorgear* r = _airplane.getModel()->getRotorgear();
 184         _currObj = r;
 185         #define p(x) if (a->hasAttribute(#x)) r->setParameter((char *)#x,attrf(a,#x) );
 186         #define p2(x,y) if (a->hasAttribute(y)) r->setParameter((char *)#x,attrf(a,y) );
 187         p2(max_power_engine,"max-power-engine")
 188         p2(engine_prop_factor,"engine-prop-factor")
 189         p(yasimdragfactor)
 190         p(yasimliftfactor)
 191         p2(max_power_rotor_brake,"max-power-rotor-brake")
 192         p2(rotorgear_friction,"rotorgear-friction")
 193         p2(engine_accel_limit,"engine-accel-limit")
 194         #undef p
 195         #undef p2
 196         r->setInUse();
 197     } else if(eq(name, "wing")) {
 198         _airplane.setWing(parseWing(a, name));
 199     } else if(eq(name, "hstab")) {
 200         _airplane.setTail(parseWing(a, name));
 201     } else if(eq(name, "vstab") || eq(name, "mstab")) {
 202         _airplane.addVStab(parseWing(a, name));
 203     } else if(eq(name, "piston-engine")) {
 204         parsePistonEngine(a);
 205     } else if(eq(name, "turbine-engine")) {
 206         parseTurbineEngine(a);
 207     } else if(eq(name, "propeller")) {
 208         parsePropeller(a);
 209     } else if(eq(name, "thruster")) {
 210         SimpleJet* j = new SimpleJet();
 211         _currObj = j;
 212         v[0] = attrf(a, "x"); v[1] = attrf(a, "y"); v[2] = attrf(a, "z");
 213         j->setPosition(v);
 214         _airplane.addThruster(j, 0, v);
 215         v[0] = attrf(a, "vx"); v[1] = attrf(a, "vy"); v[2] = attrf(a, "vz");
 216         j->setDirection(v);
 217         j->setThrust(attrf(a, "thrust") * LBS2N);
 218     } else if(eq(name, "jet")) {
 219         Jet* j = new Jet();
 220         _currObj = j;
 221         v[0] = attrf(a, "x");
 222         v[1] = attrf(a, "y");
 223         v[2] = attrf(a, "z");
 224         float mass = attrf(a, "mass") * LBS2KG;
 225         j->setMaxThrust(attrf(a, "thrust") * LBS2N,
 226                         attrf(a, "afterburner", 0) * LBS2N);
 227         j->setVectorAngle(attrf(a, "rotate", 0) * DEG2RAD);
 228         j->setReverseThrust(attrf(a, "reverse", 0.2));
 229
 230         float n1min = attrf(a, "n1-idle", 55);
 231         float n1max = attrf(a, "n1-max", 102);
 232         float n2min = attrf(a, "n2-idle", 73);
 233         float n2max = attrf(a, "n2-max", 103);
 234         j->setRPMs(n1min, n1max, n2min, n2max);
 235
 236         j->setTSFC(attrf(a, "tsfc", 0.8));
 237         if(a->hasAttribute("egt"))  j->setEGT(attrf(a, "egt"));
 238         if(a->hasAttribute("epr"))  j->setEPR(attrf(a, "epr"));
 239         if(a->hasAttribute("exhaust-speed"))
 240             j->setVMax(attrf(a, "exhaust-speed") * KTS2MPS);
 241         if(a->hasAttribute("spool-time"))
 242             j->setSpooling(attrf(a, "spool-time"));
 243
 244         j->setPosition(v);
 245         _airplane.addThruster(j, mass, v);
 246         sprintf(buf, "/engines/engine[%d]", _nextEngine++);
 247         EngRec* er = new EngRec();
 248         er->eng = j;
 249         er->prefix = dup(buf);
 250         _thrusters.add(er);
 251     } else if(eq(name, "hitch")) {
 252         Hitch* h = new Hitch(a->getValue("name"));
 253         _currObj = h;
 254         v[0] = attrf(a, "x");
 255         v[1] = attrf(a, "y");
 256         v[2] = attrf(a, "z");
 257         h->setPosition(v);
 258         if(a->hasAttribute("force-is-calculated-by-other")) h->setForceIsCalculatedByOther(attrb(a,"force-is-calculated-by-other"));
 259         _airplane.addHitch(h);
 260     } else if(eq(name, "tow")) {
 261         Hitch* h = (Hitch*)_currObj;
 262         if(a->hasAttribute("length"))
 263             h->setTowLength(attrf(a, "length"));
 264         if(a->hasAttribute("elastic-constant"))
 265             h->setTowElasticConstant(attrf(a, "elastic-constant"));
 266         if(a->hasAttribute("break-force"))
 267             h->setTowBreakForce(attrf(a, "break-force"));
 268         if(a->hasAttribute("weight-per-meter"))
 269             h->setTowWeightPerM(attrf(a, "weight-per-meter"));
 270         if(a->hasAttribute("mp-auto-connect-period"))
 271             h->setMpAutoConnectPeriod(attrf(a, "mp-auto-connect-period"));
 272     } else if(eq(name, "winch")) {
 273         Hitch* h = (Hitch*)_currObj;
 274         double pos[3];
 275         pos[0] = attrd(a, "x",0);
 276         pos[1] = attrd(a, "y",0);
 277         pos[2] = attrd(a, "z",0);
 278         h->setWinchPosition(pos);
 279         if(a->hasAttribute("max-speed"))
 280             h->setWinchMaxSpeed(attrf(a, "max-speed"));
 281         if(a->hasAttribute("power"))
 282             h->setWinchPower(attrf(a, "power") * 1000);
 283         if(a->hasAttribute("max-force"))
 284             h->setWinchMaxForce(attrf(a, "max-force"));
 285         if(a->hasAttribute("initial-tow-length"))
 286             h->setWinchInitialTowLength(attrf(a, "initial-tow-length"));
 287         if(a->hasAttribute("max-tow-length"))
 288             h->setWinchMaxTowLength(attrf(a, "max-tow-length"));
 289         if(a->hasAttribute("min-tow-length"))
 290             h->setWinchMinTowLength(attrf(a, "min-tow-length"));
 291     } else if(eq(name, "gear")) {
 292         Gear* g = new Gear();
 293         _currObj = g;
 294         v[0] = attrf(a, "x");
 295         v[1] = attrf(a, "y");
 296         v[2] = attrf(a, "z");
 297         g->setPosition(v);
 298         float nrm = Math::mag3(v);
 299         if (_vehicle_radius < nrm)
 300             _vehicle_radius = nrm;
 301         if(a->hasAttribute("upx")) {
 302             v[0] = attrf(a, "upx");
 303             v[1] = attrf(a, "upy");
 304             v[2] = attrf(a, "upz");
 305             Math::unit3(v, v);
 306         } else {
 307             v[0] = 0;
 308             v[1] = 0;
 309             v[2] = 1;
 310         }
 311         for(int i=0; i<3; i++)
 312             v[i] *= attrf(a, "compression", 1);
 313         g->setCompression(v);
 314         g->setBrake(attrf(a, "skid", 0));
 315         g->setInitialLoad(attrf(a, "initial-load", 0));
 316         g->setStaticFriction(attrf(a, "sfric", 0.8));
 317         g->setDynamicFriction(attrf(a, "dfric", 0.7));
 318         g->setSpring(attrf(a, "spring", 1));
 319         g->setDamping(attrf(a, "damp", 1));
 320         if(a->hasAttribute("on-water")) g->setOnWater(attrb(a,"on-water"));
 321         if(a->hasAttribute("on-solid")) g->setOnSolid(attrb(a,"on-solid"));
 322         if(a->hasAttribute("ignored-by-solver")) g->setIgnoreWhileSolving(attrb(a,"ignored-by-solver"));
 323         g->setSpringFactorNotPlaning(attrf(a, "spring-factor-not-planing", 1));
 324         g->setSpeedPlaning(attrf(a, "speed-planing", 0) * KTS2MPS);
 325         g->setReduceFrictionByExtension(attrf(a, "reduce-friction-by-extension", 0));
 326         _airplane.addGear(g);
 327     } else if(eq(name, "hook")) {
 328         Hook* h = new Hook();
 329         _currObj = h;
 330         v[0] = attrf(a, "x");
 331         v[1] = attrf(a, "y");
 332         v[2] = attrf(a, "z");
 333         h->setPosition(v);
 334         float length = attrf(a, "length", 1.0);
 335         h->setLength(length);
 336         float nrm = length+Math::mag3(v);
 337         if (_vehicle_radius < nrm)
 338             _vehicle_radius = nrm;
 339         h->setDownAngle(attrf(a, "down-angle", 70) * DEG2RAD);
 340         h->setUpAngle(attrf(a, "up-angle", 0) * DEG2RAD);
 341         _airplane.addHook(h);
 342     } else if(eq(name, "launchbar")) {
 343         Launchbar* l = new Launchbar();
 344         _currObj = l;
 345         v[0] = attrf(a, "x");
 346         v[1] = attrf(a, "y");
 347         v[2] = attrf(a, "z");
 348         l->setLaunchbarMount(v);
 349         v[0] = attrf(a, "holdback-x", v[0]);
 350         v[1] = attrf(a, "holdback-y", v[1]);
 351         v[2] = attrf(a, "holdback-z", v[2]);
 352         l->setHoldbackMount(v);
 353         float length = attrf(a, "length", 1.0);
 354         l->setLength(length);
 355         l->setDownAngle(attrf(a, "down-angle", 45) * DEG2RAD);
 356         l->setUpAngle(attrf(a, "up-angle", -45) * DEG2RAD);
 357         l->setHoldbackLength(attrf(a, "holdback-length", 2.0));
 358         _airplane.addLaunchbar(l);
 359     } else if(eq(name, "fuselage")) {
 360         float b[3];
 361         v[0] = attrf(a, "ax");
 362         v[1] = attrf(a, "ay");
 363         v[2] = attrf(a, "az");
 364         b[0] = attrf(a, "bx");
 365         b[1] = attrf(a, "by");
 366         b[2] = attrf(a, "bz");
 367         float taper = attrf(a, "taper", 1);
 368         float mid = attrf(a, "midpoint", 0.5);
 369         float cx = attrf(a, "cx", 1);
 370         float cy = attrf(a, "cy", 1);
 371         float cz = attrf(a, "cz", 1);
 372         float idrag = attrf(a, "idrag", 1);
 373         _airplane.addFuselage(v, b, attrf(a, "width"), taper, mid,
 374             cx, cy, cz, idrag);
 375     } else if(eq(name, "tank")) {
 376         v[0] = attrf(a, "x");
 377         v[1] = attrf(a, "y");
 378         v[2] = attrf(a, "z");
 379         float density = 6.0; // gasoline, in lbs/gal
 380         if(a->hasAttribute("jet")) density = 6.72;
 381         density *= LBS2KG*CM2GALS;
 382         _airplane.addTank(v, attrf(a, "capacity") * LBS2KG, density);
 383     } else if(eq(name, "ballast")) {
 384         v[0] = attrf(a, "x");
 385         v[1] = attrf(a, "y");
 386         v[2] = attrf(a, "z");
 387         _airplane.addBallast(v, attrf(a, "mass") * LBS2KG);
 388     } else if(eq(name, "weight")) {
 389         parseWeight(a);
 390     } else if(eq(name, "stall")) {
 391         Wing* w = (Wing*)_currObj;
 392         w->setStall(attrf(a, "aoa") * DEG2RAD);
 393         w->setStallWidth(attrf(a, "width", 2) * DEG2RAD);
 394         w->setStallPeak(attrf(a, "peak", 1.5));
 395     } else if(eq(name, "flap0")) {
 396         ((Wing*)_currObj)->setFlap0(attrf(a, "start"), attrf(a, "end"),
 397                                     attrf(a, "lift"), attrf(a, "drag"));
 398     } else if(eq(name, "flap1")) {
 399         ((Wing*)_currObj)->setFlap1(attrf(a, "start"), attrf(a, "end"),
 400                                     attrf(a, "lift"), attrf(a, "drag"));
 401     } else if(eq(name, "slat")) {
 402         ((Wing*)_currObj)->setSlat(attrf(a, "start"), attrf(a, "end"),
 403                                    attrf(a, "aoa"), attrf(a, "drag"));
 404     } else if(eq(name, "spoiler")) {
 405         ((Wing*)_currObj)->setSpoiler(attrf(a, "start"), attrf(a, "end"),
 406                                       attrf(a, "lift"), attrf(a, "drag"));
 407     /* } else if(eq(name, "collective")) {
 408         ((Rotor*)_currObj)->setcollective(attrf(a, "min"), attrf(a, "max"));
 409     } else if(eq(name, "cyclic")) {
 410         ((Rotor*)_currObj)->setcyclic(attrf(a, "ail"), attrf(a, "ele"));
 411     */
 412     } else if(eq(name, "actionpt")) {
 413         v[0] = attrf(a, "x");
 414         v[1] = attrf(a, "y");
 415         v[2] = attrf(a, "z");
 416         ((Thruster*)_currObj)->setPosition(v);
 417     } else if(eq(name, "dir")) {
 418         v[0] = attrf(a, "x");
 419         v[1] = attrf(a, "y");
 420         v[2] = attrf(a, "z");
 421         ((Thruster*)_currObj)->setDirection(v);
 422     } else if(eq(name, "control-setting")) {
 423         // A cruise or approach control setting
 424         const char* axis = a->getValue("axis");
 425         float value = attrf(a, "value", 0);
 426         if(_cruiseCurr)
 427             _airplane.addCruiseControl(parseAxis(axis), value);
 428         else
 429             _airplane.addApproachControl(parseAxis(axis), value);
 430     } else if(eq(name, "control-input")) {
 431
 432         // A mapping of input property to a control
 433         int axis = parseAxis(a->getValue("axis"));
 434         int control = parseOutput(a->getValue("control"));
 435         int opt = 0;
 436         opt |= a->hasAttribute("split") ? ControlMap::OPT_SPLIT : 0;
 437         opt |= a->hasAttribute("invert") ? ControlMap::OPT_INVERT : 0;
 438         opt |= a->hasAttribute("square") ? ControlMap::OPT_SQUARE : 0;
 439
 440         ControlMap* cm = _airplane.getControlMap();
 441         if(a->hasAttribute("src0")) {
 442                            cm->addMapping(axis, control, _currObj, opt,
 443                            attrf(a, "src0"), attrf(a, "src1"),
 444                            attrf(a, "dst0"), attrf(a, "dst1"));
 445         } else {
 446             cm->addMapping(axis, control, _currObj, opt);
 447         }
 448     } else if(eq(name, "control-output")) {
 449         // A property output for a control on the current object
 450         ControlMap* cm = _airplane.getControlMap();
 451         int type = parseOutput(a->getValue("control"));
 452         int handle = cm->getOutputHandle(_currObj, type);
 453
 454         PropOut* p = new PropOut();
 455         p->prop = fgGetNode(a->getValue("prop"), true);
 456         p->handle = handle;
 457         p->type = type;
 458         p->left = !(a->hasAttribute("side") &&
 459                         eq("right", a->getValue("side")));
 460         p->min = attrf(a, "min", cm->rangeMin(type));
 461         p->max = attrf(a, "max", cm->rangeMax(type));
 462         _controlProps.add(p);
 463
 464     } else if(eq(name, "control-speed")) {
 465         ControlMap* cm = _airplane.getControlMap();
 466         int type = parseOutput(a->getValue("control"));
 467         int handle = cm->getOutputHandle(_currObj, type);
 468         float time = attrf(a, "transition-time", 0);
 469
 470         cm->setTransitionTime(handle, time);
 471     } else {
 472         SG_LOG(SG_FLIGHT,SG_ALERT,"Unexpected tag '"
 473                << name << "' found in YASim aircraft description");
 474         exit(1);
 475     }
 476 }
 477
 478 void FGFDM::getExternalInput(float dt)
 479 {
 480     char buf[256];
 481
 482     _turb->setMagnitude(fgGetFloat("/environment/turbulence/magnitude-norm"));
 483     _turb->update(dt, fgGetFloat("/environment/turbulence/rate-hz"));
 484
 485     // The control axes
 486     ControlMap* cm = _airplane.getControlMap();
 487     cm->reset();
 488     int i;
 489     for(i=0; i<_axes.size(); i++) {
 490         AxisRec* a = (AxisRec*)_axes.get(i);
 491         float val = fgGetFloat(a->name, 0);
 492         cm->setInput(a->handle, val);
 493     }
 494     cm->applyControls(dt);
 495
 496     // Weights
 497     for(i=0; i<_weights.size(); i++) {
 498         WeightRec* wr = (WeightRec*)_weights.get(i);
 499         _airplane.setWeight(wr->handle, LBS2KG * fgGetFloat(wr->prop));
 500     }
 501
 502     for(i=0; i<_thrusters.size(); i++) {
 503         EngRec* er = (EngRec*)_thrusters.get(i);
 504         Thruster* t = er->eng;
 505
 506         if(t->getPropEngine()) {
 507             PropEngine* p = t->getPropEngine();
 508             sprintf(buf, "%s/rpm", er->prefix);
 509             p->setOmega(fgGetFloat(buf, 500) * RPM2RAD);
 510         }
 511     }
 512 }
 513
 514 // Linearly "seeks" a property by the specified fraction of the way to
 515 // the target value.  Used to emulate "slowly changing" output values.
 516 static void moveprop(SGPropertyNode* node, const char* prop,
 517                     float target, float frac)
 518 {
 519     float val = node->getFloatValue(prop);
 520     if(frac > 1) frac = 1;
 521     if(frac < 0) frac = 0;
 522     val += (target - val) * frac;
 523     node->setFloatValue(prop, val);
 524 }
 525
 526 void FGFDM::setOutputProperties(float dt)
 527 {
 528     // char buf[256];
 529     int i;
 530
 531     float grossWgt = _airplane.getModel()->getBody()->getTotalMass() * KG2LBS;
 532     fgSetFloat("/yasim/gross-weight-lbs", grossWgt);
 533
 534     ControlMap* cm = _airplane.getControlMap();
 535     for(i=0; i<_controlProps.size(); i++) {
 536         PropOut* p = (PropOut*)_controlProps.get(i);
 537         float val = (p->left
 538                      ? cm->getOutput(p->handle)
 539                      : cm->getOutputR(p->handle));
 540         float rmin = cm->rangeMin(p->type);
 541         float rmax = cm->rangeMax(p->type);
 542         float frac = (val - rmin) / (rmax - rmin);
 543         val = frac*(p->max - p->min) + p->min;
 544         p->prop->setFloatValue(val);
 545     }
 546
 547     for(i=0; i<_airplane.getRotorgear()->getNumRotors(); i++) {
 548         Rotor*r=(Rotor*)_airplane.getRotorgear()->getRotor(i);
 549         int j = 0;
 550         float f;
 551         char b[256];
 552         while((j = r->getValueforFGSet(j, b, &f)))
 553             if(b[0]) fgSetFloat(b,f);
 554         j=0;
 555         while((j = _airplane.getRotorgear()->getValueforFGSet(j, b, &f)))
 556             if(b[0]) fgSetFloat(b,f);
 557         for(j=0; j < r->numRotorparts(); j+=r->numRotorparts()>>2) {
 558             Rotorpart* s = (Rotorpart*)r->getRotorpart(j);
 559             char *b;
 560             int k;
 561             for(k=0; k<2; k++) {
 562                 b=s->getAlphaoutput(k);
 563                 if(b[0]) fgSetFloat(b, s->getAlpha(k));
 564             }
 565         }
 566     }
 567
 568     // Use the density of the first tank, or a dummy value if no tanks
 569     float fuelDensity = 1.0;
 570     if(_airplane.numTanks())
 571         fuelDensity = _airplane.getFuelDensity(0);
 572     for(i=0; i<_thrusters.size(); i++) {
 573         EngRec* er = (EngRec*)_thrusters.get(i);
 574         Thruster* t = er->eng;
 575         SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 576
 577         // Set: running, cranking, prop-thrust, max-hp, power-pct
 578         node->setBoolValue("running", t->isRunning());
 579         node->setBoolValue("cranking", t->isCranking());
 580
 581         float tmp[3];
 582         t->getThrust(tmp);
 583         float lbs = Math::mag3(tmp) * (KG2LBS/9.8);
 584         node->setFloatValue("prop-thrust", lbs); // Deprecated name
 585         node->setFloatValue("thrust-lbs", lbs);
 586         node->setFloatValue("fuel-flow-gph",
 587                             (t->getFuelFlow()/fuelDensity) * 3600 * CM2GALS);
 588
 589         if(t->getPropEngine()) {
 590             PropEngine* p = t->getPropEngine();
 591             node->setFloatValue("rpm", p->getOmega() * (1/RPM2RAD));
 592             node->setFloatValue("torque-ftlb",
 593                                 p->getEngine()->getTorque() * NM2FTLB);
 594
 595             if(p->getEngine()->isPistonEngine()) {
 596                 PistonEngine* pe = p->getEngine()->isPistonEngine();
 597                 node->setFloatValue("mp-osi", pe->getMP() * (1/INHG2PA));
 598                 node->setFloatValue("mp-inhg", pe->getMP() * (1/INHG2PA));
 599                 node->setFloatValue("egt-degf",
 600                                     pe->getEGT() * K2DEGF + K2DEGFOFFSET);
 601                 node->setFloatValue("oil-temperature-degf",
 602                                     pe->getOilTemp() * K2DEGF + K2DEGFOFFSET);
 603                 node->setFloatValue("boost-gauge-inhg",
 604                                     pe->getBoost() * (1/INHG2PA));
 605             } else if(p->getEngine()->isTurbineEngine()) {
 606                 TurbineEngine* te = p->getEngine()->isTurbineEngine();
 607                 node->setFloatValue("n2", te->getN2());
 608             }
 609         }
 610
 611         if(t->getJet()) {
 612             Jet* j = t->getJet();
 613             node->setFloatValue("n1", j->getN1());
 614             node->setFloatValue("n2", j->getN2());
 615             node->setFloatValue("epr", j->getEPR());
 616             node->setFloatValue("egt-degf",
 617                                 j->getEGT() * K2DEGF + K2DEGFOFFSET);
 618
 619             // These are "unmodeled" values that are still needed for
 620             // many cockpits.  Tie them all to the N1 speed, but
 621             // normalize the numbers to the range [0:1] so the
 622             // cockpit code can scale them to the right values.
 623             float pnorm = j->getPerfNorm();
 624             moveprop(node, "oilp-norm", pnorm, dt/3); // 3s seek time
 625             moveprop(node, "oilt-norm", pnorm, dt/30); // 30s
 626             moveprop(node, "itt-norm", pnorm, dt/1); // 1s
 627         }
 628     }
 629 }
 630
 631 Wing* FGFDM::parseWing(XMLAttributes* a, const char* type)
 632 {
 633     Wing* w = new Wing();
 634
 635     float defDihed = 0;
 636     if(eq(type, "vstab"))
 637         defDihed = 90;
 638     else
 639         w->setMirror(true);
 640
 641     float pos[3];
 642     pos[0] = attrf(a, "x");
 643     pos[1] = attrf(a, "y");
 644     pos[2] = attrf(a, "z");
 645     w->setBase(pos);
 646
 647     w->setLength(attrf(a, "length"));
 648     w->setChord(attrf(a, "chord"));
 649     w->setSweep(attrf(a, "sweep", 0) * DEG2RAD);
 650     w->setTaper(attrf(a, "taper", 1));
 651     w->setDihedral(attrf(a, "dihedral", defDihed) * DEG2RAD);
 652     w->setCamber(attrf(a, "camber", 0));
 653
 654     // These come in with positive indicating positive AoA, but the
 655     // internals expect a rotation about the left-pointing Y axis, so
 656     // invert the sign.
 657     w->setIncidence(attrf(a, "incidence", 0) * DEG2RAD * -1);
 658     w->setTwist(attrf(a, "twist", 0) * DEG2RAD * -1);
 659
 660     // The 70% is a magic number that sorta kinda seems to match known
 661     // throttle settings to approach speed.
 662     w->setInducedDrag(0.7*attrf(a, "idrag", 1));
 663
 664     float effect = attrf(a, "effectiveness", 1);
 665     w->setDragScale(w->getDragScale()*effect);
 666
 667     _currObj = w;
 668     return w;
 669 }
 670
 671 Rotor* FGFDM::parseRotor(XMLAttributes* a, const char* type)
 672 {
 673     Rotor* w = new Rotor();
 674
 675     // float defDihed = 0;
 676
 677     float pos[3];
 678     pos[0] = attrf(a, "x");
 679     pos[1] = attrf(a, "y");
 680     pos[2] = attrf(a, "z");
 681     w->setBase(pos);
 682
 683     float normal[3];
 684     normal[0] = attrf(a, "nx");
 685     normal[1] = attrf(a, "ny");
 686     normal[2] = attrf(a, "nz");
 687     w->setNormal(normal);
 688
 689     float forward[3];
 690     forward[0] = attrf(a, "fx");
 691     forward[1] = attrf(a, "fy");
 692     forward[2] = attrf(a, "fz");
 693     w->setForward(forward);
 694
 695     w->setMaxCyclicail(attrf(a, "maxcyclicail", 7.6));
 696     w->setMaxCyclicele(attrf(a, "maxcyclicele", 4.94));
 697     w->setMinCyclicail(attrf(a, "mincyclicail", -7.6));
 698     w->setMinCyclicele(attrf(a, "mincyclicele", -4.94));
 699     w->setMaxCollective(attrf(a, "maxcollective", 15.8));
 700     w->setMinCollective(attrf(a, "mincollective", -0.2));
 701     w->setDiameter(attrf(a, "diameter", 10.2));
 702     w->setWeightPerBlade(attrf(a, "weightperblade", 44));
 703     w->setNumberOfBlades(attrf(a, "numblades", 4));
 704     w->setRelBladeCenter(attrf(a, "relbladecenter", 0.7));
 705     w->setDynamic(attrf(a, "dynamic", 0.7));
 706     w->setDelta3(attrf(a, "delta3", 0));
 707     w->setDelta(attrf(a, "delta", 0));
 708     w->setTranslift(attrf(a, "translift", 0.05));
 709     w->setC2(attrf(a, "dragfactor", 1));
 710     w->setStepspersecond(attrf(a, "stepspersecond", 120));
 711     w->setPhiNull((attrf(a, "phi0", 0))*YASIM_PI/180);
 712     w->setRPM(attrf(a, "rpm", 424));
 713     w->setRelLenHinge(attrf(a, "rellenflaphinge", 0.07));
 714     w->setAlpha0((attrf(a, "flap0", -5))*YASIM_PI/180);
 715     w->setAlphamin((attrf(a, "flapmin", -15))/180*YASIM_PI);
 716     w->setAlphamax((attrf(a, "flapmax",  15))*YASIM_PI/180);
 717     w->setAlpha0factor(attrf(a, "flap0factor", 1));
 718     w->setTeeterdamp(attrf(a,"teeterdamp",.0001));
 719     w->setMaxteeterdamp(attrf(a,"maxteeterdamp",1000));
 720     w->setRelLenTeeterHinge(attrf(a,"rellenteeterhinge",0.01));
 721     w->setBalance(attrf(a,"balance",1.0));
 722     w->setMinTiltYaw(attrf(a,"mintiltyaw",0.0));
 723     w->setMinTiltPitch(attrf(a,"mintiltpitch",0.0));
 724     w->setMinTiltRoll(attrf(a,"mintiltroll",0.0));
 725     w->setMaxTiltYaw(attrf(a,"maxtiltyaw",0.0));
 726     w->setMaxTiltPitch(attrf(a,"maxtiltpitch",0.0));
 727     w->setMaxTiltRoll(attrf(a,"maxtiltroll",0.0));
 728     w->setTiltCenterX(attrf(a,"tiltcenterx",0.0));
 729     w->setTiltCenterY(attrf(a,"tiltcentery",0.0));
 730     w->setTiltCenterZ(attrf(a,"tiltcenterz",0.0));
 731     w->setDownwashFactor(attrf(a, "downwashfactor", 1));
 732     if(attrb(a,"ccw"))
 733        w->setCcw(1);
 734     if(attrb(a,"sharedflaphinge"))
 735        w->setSharedFlapHinge(true);
 736
 737     if(a->hasAttribute("name"))
 738        w->setName(a->getValue("name") );
 739     if(a->hasAttribute("alphaout0"))
 740        w->setAlphaoutput(0,a->getValue("alphaout0") );
 741     if(a->hasAttribute("alphaout1"))  w->setAlphaoutput(1,a->getValue("alphaout1") );
 742     if(a->hasAttribute("alphaout2"))  w->setAlphaoutput(2,a->getValue("alphaout2") );
 743     if(a->hasAttribute("alphaout3"))  w->setAlphaoutput(3,a->getValue("alphaout3") );
 744     if(a->hasAttribute("coneout"))  w->setAlphaoutput(4,a->getValue("coneout") );
 745     if(a->hasAttribute("yawout"))   w->setAlphaoutput(5,a->getValue("yawout") );
 746     if(a->hasAttribute("rollout"))  w->setAlphaoutput(6,a->getValue("rollout") );
 747
 748     w->setPitchA(attrf(a, "pitch-a", 10));
 749     w->setPitchB(attrf(a, "pitch-b", 10));
 750     w->setForceAtPitchA(attrf(a, "forceatpitch-a", 3000));
 751     w->setPowerAtPitch0(attrf(a, "poweratpitch-0", 300));
 752     w->setPowerAtPitchB(attrf(a, "poweratpitch-b", 3000));
 753     if(attrb(a,"notorque"))
 754        w->setNotorque(1);
 755
 756 #define p(x) if (a->hasAttribute(#x)) w->setParameter((char *)#x,attrf(a,#x) );
 757 #define p2(x,y) if (a->hasAttribute(y)) w->setParameter((char *)#x,attrf(a,y) );
 758     p2(translift_ve,"translift-ve")
 759     p2(translift_maxfactor,"translift-maxfactor")
 760     p2(ground_effect_constant,"ground-effect-constant")
 761     p2(vortex_state_lift_factor,"vortex-state-lift-factor")
 762     p2(vortex_state_c1,"vortex-state-c1")
 763     p2(vortex_state_c2,"vortex-state-c2")
 764     p2(vortex_state_c3,"vortex-state_c3")
 765     p2(vortex_state_e1,"vortex-state-e1")
 766     p2(vortex_state_e2,"vortex-state-e2")
 767     p(twist)
 768     p2(number_of_segments,"number-of-segments")
 769     p2(number_of_parts,"number-of-parts")
 770     p2(rel_len_where_incidence_is_measured,"rel-len-where-incidence-is-measured")
 771     p(chord)
 772     p(taper)
 773     p2(airfoil_incidence_no_lift,"airfoil-incidence-no-lift")
 774     p2(rel_len_blade_start,"rel-len-blade-start")
 775     p2(incidence_stall_zero_speed,"incidence-stall-zero-speed")
 776     p2(incidence_stall_half_sonic_speed,"incidence-stall-half-sonic-speed")
 777     p2(lift_factor_stall,"lift-factor-stall")
 778     p2(stall_change_over,"stall-change-over")
 779     p2(drag_factor_stall,"drag-factor-stall")
 780     p2(airfoil_lift_coefficient,"airfoil-lift-coefficient")
 781     p2(airfoil_drag_coefficient0,"airfoil-drag-coefficient0")
 782     p2(airfoil_drag_coefficient1,"airfoil-drag-coefficient1")
 783     p2(cyclic_factor,"cyclic-factor")
 784     p2(rotor_correction_factor,"rotor-correction-factor")
 785 #undef p
 786 #undef p2
 787     _currObj = w;
 788     return w;
 789 }
 790
 791 void FGFDM::parsePistonEngine(XMLAttributes* a)
 792 {
 793     float engP = attrf(a, "eng-power") * HP2W;
 794     float engS = attrf(a, "eng-rpm") * RPM2RAD;
 795
 796     PistonEngine* eng = new PistonEngine(engP, engS);
 797
 798     if(a->hasAttribute("displacement"))
 799         eng->setDisplacement(attrf(a, "displacement") * CIN2CM);
 800
 801     if(a->hasAttribute("compression"))
 802         eng->setCompression(attrf(a, "compression"));
 803
 804     if(a->hasAttribute("min-throttle"))
 805         eng->setMinThrottle(attrf(a, "min-throttle"));
 806
 807     if(a->hasAttribute("turbo-mul")) {
 808         float mul = attrf(a, "turbo-mul");
 809         float mp = attrf(a, "wastegate-mp", 1e6) * INHG2PA;
 810         eng->setTurboParams(mul, mp);
 811         eng->setTurboLag(attrf(a, "turbo-lag", 2));
 812     }
 813
 814     if(a->hasAttribute("supercharger"))
 815         eng->setSupercharger(attrb(a, "supercharger"));
 816
 817     ((PropEngine*)_currObj)->setEngine(eng);
 818 }
 819
 820 void FGFDM::parseTurbineEngine(XMLAttributes* a)
 821 {
 822     float power = attrf(a, "eng-power") * HP2W;
 823     float omega = attrf(a, "eng-rpm") * RPM2RAD;
 824     float alt = attrf(a, "alt") * FT2M;
 825     float flatRating = attrf(a, "flat-rating") * HP2W;
 826     TurbineEngine* eng = new TurbineEngine(power, omega, alt, flatRating);
 827
 828     if(a->hasAttribute("n2-low-idle"))
 829         eng->setN2Range(attrf(a, "n2-low-idle"), attrf(a, "n2-high-idle"),
 830                         attrf(a, "n2-max"));
 831
 832     // Nasty units conversion: lbs/hr per hp -> kg/s per watt
 833     if(a->hasAttribute("bsfc"))
 834         eng->setFuelConsumption(attrf(a, "bsfc") * (LBS2KG/(3600*HP2W)));
 835
 836     ((PropEngine*)_currObj)->setEngine(eng);
 837 }
 838
 839 void FGFDM::parsePropeller(XMLAttributes* a)
 840 {
 841     // Legacy Handling for the old engines syntax:
 842     PistonEngine* eng = 0;
 843     if(a->hasAttribute("eng-power")) {
 844         SG_LOG(SG_FLIGHT,SG_ALERT, "WARNING: "
 845                << "Legacy engine definition in YASim configuration file.  "
 846                << "Please fix.");
 847         float engP = attrf(a, "eng-power") * HP2W;
 848         float engS = attrf(a, "eng-rpm") * RPM2RAD;
 849         eng = new PistonEngine(engP, engS);
 850         if(a->hasAttribute("displacement"))
 851             eng->setDisplacement(attrf(a, "displacement") * CIN2CM);
 852         if(a->hasAttribute("compression"))
 853             eng->setCompression(attrf(a, "compression"));
 854         if(a->hasAttribute("turbo-mul")) {
 855             float mul = attrf(a, "turbo-mul");
 856             float mp = attrf(a, "wastegate-mp", 1e6) * INHG2PA;
 857             eng->setTurboParams(mul, mp);
 858         }
 859     }
 860
 861     // Now parse the actual propeller definition:
 862     float cg[3];
 863     cg[0] = attrf(a, "x");
 864     cg[1] = attrf(a, "y");
 865     cg[2] = attrf(a, "z");
 866     float mass = attrf(a, "mass") * LBS2KG;
 867     float moment = attrf(a, "moment");
 868     float radius = attrf(a, "radius");
 869     float speed = attrf(a, "cruise-speed") * KTS2MPS;
 870     float omega = attrf(a, "cruise-rpm") * RPM2RAD;
 871     float power = attrf(a, "cruise-power") * HP2W;
 872     float rho = Atmosphere::getStdDensity(attrf(a, "cruise-alt") * FT2M);
 873
 874     Propeller* prop = new Propeller(radius, speed, omega, rho, power);
 875     PropEngine* thruster = new PropEngine(prop, eng, moment);
 876     _airplane.addThruster(thruster, mass, cg);
 877
 878     // Set the stops (fine = minimum pitch, coarse = maximum pitch)
 879     float fine_stop = attrf(a, "fine-stop", 0.25f);
 880     float coarse_stop = attrf(a, "coarse-stop", 4.0f);
 881     prop->setStops(fine_stop, coarse_stop);
 882
 883     if(a->hasAttribute("takeoff-power")) {
 884         float power0 = attrf(a, "takeoff-power") * HP2W;
 885         float omega0 = attrf(a, "takeoff-rpm") * RPM2RAD;
 886         prop->setTakeoff(omega0, power0);
 887     }
 888
 889     if(a->hasAttribute("max-rpm")) {
 890         float max = attrf(a, "max-rpm") * RPM2RAD;
 891         float min = attrf(a, "min-rpm") * RPM2RAD;
 892         thruster->setVariableProp(min, max);
 893     }
 894
 895     if(attrb(a, "contra"))
 896         thruster->setContraPair(true);
 897
 898     if(a->hasAttribute("manual-pitch")) {
 899         prop->setManualPitch();
 900     }
 901
 902     thruster->setGearRatio(attrf(a, "gear-ratio", 1));
 903
 904     char buf[64];
 905     sprintf(buf, "/engines/engine[%d]", _nextEngine++);
 906     EngRec* er = new EngRec();
 907     er->eng = thruster;
 908     er->prefix = dup(buf);
 909     _thrusters.add(er);
 910
 911     _currObj = thruster;
 912 }
 913
 914 // Turns a string axis name into an integer for use by the
 915 // ControlMap.  Creates a new axis if this one hasn't been defined
 916 // yet.
 917 int FGFDM::parseAxis(const char* name)
 918 {
 919     int i;
 920     for(i=0; i<_axes.size(); i++) {
 921         AxisRec* a = (AxisRec*)_axes.get(i);
 922         if(eq(a->name, name))
 923             return a->handle;
 924     }
 925
 926     // Not there, make a new one.
 927     AxisRec* a = new AxisRec();
 928     a->name = dup(name);
 929     fgGetNode( a->name, true ); // make sure the property name exists
 930     a->handle = _airplane.getControlMap()->newInput();
 931     _axes.add(a);
 932     return a->handle;
 933 }
 934
 935 int FGFDM::parseOutput(const char* name)
 936 {
 937     if(eq(name, "THROTTLE"))  return ControlMap::THROTTLE;
 938     if(eq(name, "MIXTURE"))   return ControlMap::MIXTURE;
 939     if(eq(name, "CONDLEVER")) return ControlMap::CONDLEVER;
 940     if(eq(name, "STARTER"))   return ControlMap::STARTER;
 941     if(eq(name, "MAGNETOS"))  return ControlMap::MAGNETOS;
 942     if(eq(name, "ADVANCE"))   return ControlMap::ADVANCE;
 943     if(eq(name, "REHEAT"))    return ControlMap::REHEAT;
 944     if(eq(name, "BOOST"))     return ControlMap::BOOST;
 945     if(eq(name, "VECTOR"))    return ControlMap::VECTOR;
 946     if(eq(name, "PROP"))      return ControlMap::PROP;
 947     if(eq(name, "BRAKE"))     return ControlMap::BRAKE;
 948     if(eq(name, "STEER"))     return ControlMap::STEER;
 949     if(eq(name, "EXTEND"))    return ControlMap::EXTEND;
 950     if(eq(name, "HEXTEND"))   return ControlMap::HEXTEND;
 951     if(eq(name, "LEXTEND"))   return ControlMap::LEXTEND;
 952         if(eq(name, "LACCEL"))    return ControlMap::LACCEL;
 953     if(eq(name, "INCIDENCE")) return ControlMap::INCIDENCE;
 954     if(eq(name, "FLAP0"))     return ControlMap::FLAP0;
 955     if(eq(name, "FLAP0EFFECTIVENESS"))   return ControlMap::FLAP0EFFECTIVENESS;
 956     if(eq(name, "FLAP1"))     return ControlMap::FLAP1;
 957     if(eq(name, "FLAP1EFFECTIVENESS"))   return ControlMap::FLAP1EFFECTIVENESS;
 958     if(eq(name, "SLAT"))      return ControlMap::SLAT;
 959     if(eq(name, "SPOILER"))   return ControlMap::SPOILER;
 960     if(eq(name, "CASTERING")) return ControlMap::CASTERING;
 961     if(eq(name, "PROPPITCH")) return ControlMap::PROPPITCH;
 962     if(eq(name, "PROPFEATHER")) return ControlMap::PROPFEATHER;
 963     if(eq(name, "COLLECTIVE")) return ControlMap::COLLECTIVE;
 964     if(eq(name, "CYCLICAIL")) return ControlMap::CYCLICAIL;
 965     if(eq(name, "CYCLICELE")) return ControlMap::CYCLICELE;
 966     if(eq(name, "TILTROLL")) return ControlMap::TILTROLL;
 967     if(eq(name, "TILTPITCH")) return ControlMap::TILTPITCH;
 968     if(eq(name, "TILTYAW")) return ControlMap::TILTYAW;
 969     if(eq(name, "ROTORGEARENGINEON")) return ControlMap::ROTORENGINEON;
 970     if(eq(name, "ROTORBRAKE")) return ControlMap::ROTORBRAKE;
 971     if(eq(name, "ROTORENGINEMAXRELTORQUE"))
 972         return ControlMap::ROTORENGINEMAXRELTORQUE;
 973     if(eq(name, "ROTORRELTARGET")) return ControlMap::ROTORRELTARGET;
 974     if(eq(name, "ROTORBALANCE")) return ControlMap::ROTORBALANCE;
 975     if(eq(name, "REVERSE_THRUST")) return ControlMap::REVERSE_THRUST;
 976     if(eq(name, "WASTEGATE")) return ControlMap::WASTEGATE;
 977     if(eq(name, "WINCHRELSPEED")) return ControlMap::WINCHRELSPEED;
 978     if(eq(name, "HITCHOPEN")) return ControlMap::HITCHOPEN;
 979     if(eq(name, "PLACEWINCH")) return ControlMap::PLACEWINCH;
 980     if(eq(name, "FINDAITOW")) return ControlMap::FINDAITOW;
 981
 982     SG_LOG(SG_FLIGHT,SG_ALERT,"Unrecognized control type '"
 983            << name << "' in YASim aircraft description.");
 984     exit(1);
 985
 986 }
 987
 988 void FGFDM::parseWeight(XMLAttributes* a)
 989 {
 990     WeightRec* wr = new WeightRec();
 991
 992     float v[3];
 993     v[0] = attrf(a, "x");
 994     v[1] = attrf(a, "y");
 995     v[2] = attrf(a, "z");
 996
 997     wr->prop = dup(a->getValue("mass-prop"));
 998     wr->size = attrf(a, "size", 0);
 999     wr->handle = _airplane.addWeight(v, wr->size);
1000
1001     _weights.add(wr);
1002 }
1003
1004 bool FGFDM::eq(const char* a, const char* b)
1005 {
1006     // Figure it out for yourself. :)
1007     while(*a && *b && *a == *b) { a++; b++; }
1008     return !(*a || *b);
1009 }
1010
1011 char* FGFDM::dup(const char* s)
1012 {
1013     int len=0;
1014     while(s[len++]);
1015     char* s2 = new char[len+1];
1016     char* p = s2;
1017     while((*p++ = *s++));
1018     s2[len] = 0;
1019     return s2;
1020 }
1021
1022 int FGFDM::attri(XMLAttributes* atts, const char* attr)
1023 {
1024     if(!atts->hasAttribute(attr)) {
1025         SG_LOG(SG_FLIGHT,SG_ALERT,"Missing '" << attr <<
1026                "' in YASim aircraft description");
1027         exit(1);
1028     }
1029     return attri(atts, attr, 0);
1030 }
1031
1032 int FGFDM::attri(XMLAttributes* atts, const char* attr, int def)
1033 {
1034     const char* val = atts->getValue(attr);
1035     if(val == 0) return def;
1036     else         return atol(val);
1037 }
1038
1039 float FGFDM::attrf(XMLAttributes* atts, const char* attr)
1040 {
1041     if(!atts->hasAttribute(attr)) {
1042         SG_LOG(SG_FLIGHT,SG_ALERT,"Missing '" << attr <<
1043                "' in YASim aircraft description");
1044         exit(1);
1045     }
1046     return attrf(atts, attr, 0);
1047 }
1048
1049 float FGFDM::attrf(XMLAttributes* atts, const char* attr, float def)
1050 {
1051     const char* val = atts->getValue(attr);
1052     if(val == 0) return def;
1053     else         return (float)atof(val);
1054 }
1055
1056 double FGFDM::attrd(XMLAttributes* atts, const char* attr)
1057 {
1058     if(!atts->hasAttribute(attr)) {
1059         SG_LOG(SG_FLIGHT,SG_ALERT,"Missing '" << attr <<
1060                "' in YASim aircraft description");
1061         exit(1);
1062     }
1063     return attrd(atts, attr, 0);
1064 }
1065
1066 double FGFDM::attrd(XMLAttributes* atts, const char* attr, double def)
1067 {
1068     const char* val = atts->getValue(attr);
1069     if(val == 0) return def;
1070     else         return atof(val);
1071 }
1072
1073 // ACK: the dreaded ambiguous string boolean.  Remind me to shoot Maik
1074 // when I have a chance. :).  Unless you have a parser that can check
1075 // symbol constants (we don't), this kind of coding is just a Bad
1076 // Idea.  This implementation, for example, silently returns a boolean
1077 // falsehood for values of "1", "yes", "True", and "TRUE".  Which is
1078 // especially annoying preexisting boolean attributes in the same
1079 // parser want to see "1" and will choke on a "true"...
1080 //
1081 // Unfortunately, this usage creeped into existing configuration files
1082 // while I wasn't active, and it's going to be hard to remove.  Issue
1083 // a warning to nag people into changing their ways for now...
1084 bool FGFDM::attrb(XMLAttributes* atts, const char* attr)
1085 {
1086     const char* val = atts->getValue(attr);
1087     if(val == 0) return false;
1088
1089     if(eq(val,"true")) {
1090         SG_LOG(SG_FLIGHT, SG_ALERT, "Warning: " <<
1091                "deprecated 'true' boolean in YASim configuration file.  " <<
1092                "Use numeric booleans (attribute=\"1\") instead");
1093         return true;
1094     }
1095     return attri(atts, attr, 0) ? true : false;
1096 }
1097
1098 }; // namespace yasim