src/Instrumentation/dclgps.cxx

   1 // dclgps.cxx - a class to extend the operation of FG's current GPS
   2 // code, and provide support for a KLN89-specific instrument.  It
   3 // is envisioned that eventually this file and class will be split
   4 // up between current FG code and new KLN89-specific code and removed.
   5 //
   6 // Written by David Luff, started 2005.
   7 //
   8 // Copyright (C) 2005 - David C Luff:  daveluff --AT-- ntlworld --D0T-- com
   9 //
  10 // This program is free software; you can redistribute it and/or
  11 // modify it under the terms of the GNU General Public License as
  12 // published by the Free Software Foundation; either version 2 of the
  13 // License, or (at your option) any later version.
  14 //
  15 // This program is distributed in the hope that it will be useful, but
  16 // WITHOUT ANY WARRANTY; without even the implied warranty of
  17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 // General Public License for more details.
  19 //
  20 // You should have received a copy of the GNU General Public License
  21 // along with this program; if not, write to the Free Software
  22 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  23 //
  24 // $Id$
  25
  26 #include "dclgps.hxx"
  27
  28 #include <simgear/sg_inlines.h>
  29 #include <simgear/timing/sg_time.hxx>
  30 #include <simgear/magvar/magvar.hxx>
  31
  32 #include <Main/fg_props.hxx>
  33 #include <Navaids/fix.hxx>
  34 #include <Navaids/navrecord.hxx>
  35 #include <Airports/simple.hxx>
  36 #include <Airports/runways.hxx>
  37
  38 #include <iostream>
  39
  40 using namespace std;
  41
  42 GPSWaypoint::GPSWaypoint() {
  43     appType = GPS_APP_NONE;
  44 }
  45
  46 GPSWaypoint::GPSWaypoint(const std::string& aIdent, float aLat, float aLon, GPSWpType aType) :
  47   id(aIdent),
  48   lat(aLat),
  49   lon(aLon),
  50   type(aType),
  51   appType(GPS_APP_NONE)
  52 {
  53 }
  54
  55 GPSWaypoint::~GPSWaypoint() {}
  56
  57 string GPSWaypoint::GetAprId() {
  58         if(appType == GPS_IAF) return(id + 'i');
  59         else if(appType == GPS_FAF) return(id + 'f');
  60         else if(appType == GPS_MAP) return(id + 'm');
  61         else if(appType == GPS_MAHP) return(id + 'h');
  62         else return(id);
  63 }
  64
  65 static GPSWpType
  66 GPSWpTypeFromFGPosType(FGPositioned::Type aType)
  67 {
  68   switch (aType) {
  69   case FGPositioned::AIRPORT:
  70   case FGPositioned::SEAPORT:
  71   case FGPositioned::HELIPORT:
  72     return GPS_WP_APT;
  73
  74   case FGPositioned::VOR:
  75     return GPS_WP_VOR;
  76
  77   case FGPositioned::NDB:
  78     return GPS_WP_NDB;
  79
  80   case FGPositioned::WAYPOINT:
  81     return GPS_WP_USR;
  82
  83   case FGPositioned::FIX:
  84     return GPS_WP_INT;
  85
  86   default:
  87     return GPS_WP_USR;
  88   }
  89 }
  90
  91 GPSWaypoint* GPSWaypoint::createFromPositioned(const FGPositioned* aPos)
  92 {
  93   if (!aPos) {
  94     return NULL; // happens if find returns no match
  95   }
  96
  97   return new GPSWaypoint(aPos->ident(),
  98     aPos->latitude() * SG_DEGREES_TO_RADIANS,
  99     aPos->longitude() * SG_DEGREES_TO_RADIANS,
 100     GPSWpTypeFromFGPosType(aPos->type())
 101   );
 102 }
 103
 104 ostream& operator << (ostream& os, GPSAppWpType type) {
 105         switch(type) {
 106                 case(GPS_IAF):       return(os << "IAF");
 107                 case(GPS_IAP):       return(os << "IAP");
 108                 case(GPS_FAF):       return(os << "FAF");
 109                 case(GPS_MAP):       return(os << "MAP");
 110                 case(GPS_MAHP):      return(os << "MAHP");
 111                 case(GPS_HDR):       return(os << "HEADER");
 112                 case(GPS_FENCE):     return(os << "FENCE");
 113                 case(GPS_APP_NONE):  return(os << "NONE");
 114         }
 115         return(os << "ERROR - Unknown switch in GPSAppWpType operator << ");
 116 }
 117
 118 FGIAP::FGIAP() {
 119 }
 120
 121 FGIAP::~FGIAP() {
 122 }
 123
 124 FGNPIAP::FGNPIAP() {
 125 }
 126
 127 FGNPIAP::~FGNPIAP() {
 128 }
 129
 130 ClockTime::ClockTime() {
 131     _hr = 0;
 132     _min = 0;
 133 }
 134
 135 ClockTime::ClockTime(int hr, int min) {
 136     while(hr < 0) { hr += 24; }
 137     _hr = hr % 24;
 138     while(min < 0) { min += 60; }
 139     while(min > 60) { min -= 60; }
 140         _min = min;
 141 }
 142
 143 ClockTime::~ClockTime() {
 144 }
 145
 146 // ------------------------------------------------------------------------------------- //
 147
 148 DCLGPS::DCLGPS(RenderArea2D* instrument) {
 149         _instrument = instrument;
 150         _nFields = 1;
 151         _maxFields = 2;
 152
 153         // Units - lets default to US units - FG can set them to other units from config during startup if desired.
 154         _altUnits = GPS_ALT_UNITS_FT;
 155         _baroUnits = GPS_PRES_UNITS_IN;
 156         _velUnits = GPS_VEL_UNITS_KT;
 157         _distUnits = GPS_DIST_UNITS_NM;
 158
 159         _lon_node = fgGetNode("/instrumentation/gps/indicated-longitude-deg", true);
 160         _lat_node = fgGetNode("/instrumentation/gps/indicated-latitude-deg", true);
 161         _alt_node = fgGetNode("/instrumentation/gps/indicated-altitude-ft", true);
 162         _grnd_speed_node = fgGetNode("/instrumentation/gps/indicated-ground-speed-kt", true);
 163         _true_track_node = fgGetNode("/instrumentation/gps/indicated-track-true-deg", true);
 164         _mag_track_node = fgGetNode("/instrumentation/gps/indicated-track-magnetic-deg", true);
 165
 166         // Use FG's position values at construction in case FG's gps has not run first update yet.
 167         _lon = fgGetDouble("/position/longitude-deg") * SG_DEGREES_TO_RADIANS;
 168         _lat = fgGetDouble("/position/latitude-deg") * SG_DEGREES_TO_RADIANS;
 169         _alt = fgGetDouble("/position/altitude-ft");
 170         // Note - we can depriciate _gpsLat and _gpsLon if we implement error handling in FG
 171         // gps code and not our own.
 172         _gpsLon = _lon;
 173         _gpsLat = _lat;
 174         _checkLon = _gpsLon;
 175         _checkLat = _gpsLat;
 176         _groundSpeed_ms = 0.0;
 177         _groundSpeed_kts = 0.0;
 178         _track = 0.0;
 179         _magTrackDeg = 0.0;
 180
 181         // Sensible defaults.  These can be overriden by derived classes if desired.
 182         _cdiScales.clear();
 183         _cdiScales.push_back(5.0);
 184         _cdiScales.push_back(1.0);
 185         _cdiScales.push_back(0.3);
 186         _currentCdiScaleIndex = 0;
 187         _targetCdiScaleIndex = 0;
 188         _sourceCdiScaleIndex = 0;
 189         _cdiScaleTransition = false;
 190         _currentCdiScale = 5.0;
 191
 192         _cleanUpPage = -1;
 193
 194         _activeWaypoint.id.clear();
 195         _dist2Act = 0.0;
 196         _crosstrackDist = 0.0;
 197         _headingBugTo = true;
 198         _navFlagged = true;
 199         _waypointAlert = false;
 200         _departed = false;
 201         _departureTimeString = "----";
 202         _elapsedTime = 0.0;
 203         _powerOnTime.set_hr(0);
 204         _powerOnTime.set_min(0);
 205         _powerOnTimerSet = false;
 206         _alarmSet = false;
 207
 208         // Configuration Initialisation
 209         // Should this be in kln89.cxx ?
 210         _turnAnticipationEnabled = false;
 211         _suaAlertEnabled = false;
 212         _altAlertEnabled = false;
 213
 214         _time = new SGTime;
 215
 216         _messageStack.clear();
 217
 218         _dto = false;
 219
 220         _approachLoaded = false;
 221         _approachArm = false;
 222         _approachReallyArmed = false;
 223         _approachActive = false;
 224         _approachFP = new GPSFlightPlan;
 225 }
 226
 227 DCLGPS::~DCLGPS() {
 228         delete _time;
 229   delete _approachFP;           // Don't need to delete the waypoints inside since they point to
 230                                                         // the waypoints in the approach database.
 231         // TODO - may need to delete the approach database!!
 232 }
 233
 234 void DCLGPS::draw(osg::State& state) {
 235         _instrument->draw(state);
 236 }
 237
 238 void DCLGPS::init() {
 239
 240         // Not sure if this should be here, but OK for now.
 241         CreateDefaultFlightPlans();
 242
 243         // Hack - hardwire some instrument approaches for development.
 244         // These will shortly be replaced by a routine to read ARINC data from file instead.
 245         FGNPIAP* iap;
 246         GPSWaypoint* wp;
 247         GPSFlightPlan* fp;
 248         const GPSWaypoint* cwp;
 249
 250         iap = new FGNPIAP;
 251         iap->_aptIdent = "KHAF";
 252         iap->_ident = "R12-Y";
 253         iap->_name = ExpandSIAPIdent(iap->_ident);
 254         iap->_rwyStr = "12";
 255         iap->_approachRoutes.clear();
 256         iap->_IAP.clear();
 257         iap->_MAP.clear();
 258         // -------
 259         wp = new GPSWaypoint;
 260         wp->id = "GOBBS";
 261         // Nasty using the find any function here, but it saves converting data from FGFix etc.
 262         cwp = FindFirstByExactId(wp->id);
 263         if(cwp) {
 264                 *wp = *cwp;
 265                 wp->appType = GPS_IAF;
 266                 fp = new GPSFlightPlan;
 267                 fp->waypoints.push_back(wp);
 268         } else {
 269                 //cout << "Unable to find waypoint " << wp->id << '\n';
 270         }
 271         // -------
 272         wp = new GPSWaypoint;
 273         wp->id = "FUJCE";
 274         cwp = FindFirstByExactId(wp->id);
 275         if(cwp) {
 276                 *wp = *cwp;
 277                 wp->appType = GPS_IAP;
 278                 fp->waypoints.push_back(wp);
 279                 iap->_approachRoutes.push_back(fp);
 280                 iap->_IAP.push_back(wp);
 281         } else {
 282                 //cout << "Unable to find waypoint " << wp->id << '\n';
 283         }
 284         // -------
 285         wp = new GPSWaypoint;
 286         wp->id = "JEVXY";
 287         cwp = FindFirstByExactId(wp->id);
 288         if(cwp) {
 289                 *wp = *cwp;
 290                 wp->appType = GPS_FAF;
 291                 iap->_IAP.push_back(wp);
 292         } else {
 293                 //cout << "Unable to find waypoint " << wp->id << '\n';
 294         }
 295         // -------
 296         wp = new GPSWaypoint;
 297         wp->id = "RW12";
 298         wp->appType = GPS_MAP;
 299         if(wp->id.substr(0, 2) == "RW" && wp->appType == GPS_MAP) {
 300                 // Assume that this is a missed-approach point based on the runway number, which appears to be standard for most approaches.
 301                 const FGAirport* apt = fgFindAirportID(iap->_aptIdent);
 302                 if(apt) {
 303                         // TODO - sanity check the waypoint ID to ensure we have a double digit number
 304                         FGRunway* rwy = apt->getRunwayByIdent(wp->id.substr(2, 2));
 305                         if(rwy) {
 306                                 wp->lat = rwy->begin().getLatitudeRad();
 307                                 wp->lon = rwy->begin().getLongitudeRad();
 308                         }
 309                 }
 310         } else {
 311                 cwp = FindFirstByExactId(wp->id);
 312                 if(cwp) {
 313                         *wp = *cwp;
 314                         wp->appType = GPS_MAP;
 315                 } else {
 316                         //cout << "Unable to find waypoint " << wp->id << '\n';
 317                 }
 318         }
 319         iap->_IAP.push_back(wp);
 320         // -------
 321         wp = new GPSWaypoint;
 322         wp->id = "SEEMS";
 323         cwp = FindFirstByExactId(wp->id);
 324         if(cwp) {
 325                 *wp = *cwp;
 326                 wp->appType = GPS_MAHP;
 327                 iap->_MAP.push_back(wp);
 328         } else {
 329                 //cout << "Unable to find waypoint " << wp->id << '\n';
 330         }
 331         // -------
 332         _np_iap[iap->_aptIdent].push_back(iap);
 333 }
 334
 335 void DCLGPS::bind() {
 336         fgTie("/instrumentation/gps/waypoint-alert", this, &DCLGPS::GetWaypointAlert);
 337         fgTie("/instrumentation/gps/leg-mode", this, &DCLGPS::GetLegMode);
 338         fgTie("/instrumentation/gps/obs-mode", this, &DCLGPS::GetOBSMode);
 339         fgTie("/instrumentation/gps/approach-arm", this, &DCLGPS::GetApproachArm);
 340         fgTie("/instrumentation/gps/approach-active", this, &DCLGPS::GetApproachActive);
 341         fgTie("/instrumentation/gps/cdi-deflection", this, &DCLGPS::GetCDIDeflection);
 342         fgTie("/instrumentation/gps/to-flag", this, &DCLGPS::GetToFlag);
 343 }
 344
 345 void DCLGPS::unbind() {
 346         fgUntie("/instrumentation/gps/waypoint-alert");
 347         fgUntie("/instrumentation/gps/leg-mode");
 348         fgUntie("/instrumentation/gps/obs-mode");
 349         fgUntie("/instrumentation/gps/approach-arm");
 350         fgUntie("/instrumentation/gps/approach-active");
 351         fgUntie("/instrumentation/gps/cdi-deflection");
 352 }
 353
 354 void DCLGPS::update(double dt) {
 355         //cout << "update called!\n";
 356
 357         _lon = _lon_node->getDoubleValue() * SG_DEGREES_TO_RADIANS;
 358         _lat = _lat_node->getDoubleValue() * SG_DEGREES_TO_RADIANS;
 359         _alt = _alt_node->getDoubleValue();
 360         _groundSpeed_kts = _grnd_speed_node->getDoubleValue();
 361         _groundSpeed_ms = _groundSpeed_kts * 0.5144444444;
 362         _track = _true_track_node->getDoubleValue();
 363         _magTrackDeg = _mag_track_node->getDoubleValue();
 364         // Note - we can depriciate _gpsLat and _gpsLon if we implement error handling in FG
 365         // gps code and not our own.
 366         _gpsLon = _lon;
 367         _gpsLat = _lat;
 368         // Check for abnormal position slew
 369         if(GetGreatCircleDistance(_gpsLat, _gpsLon, _checkLat, _checkLon) > 1.0) {
 370                 OrientateToActiveFlightPlan();
 371         }
 372         _checkLon = _gpsLon;
 373         _checkLat = _gpsLat;
 374
 375         // TODO - check for unit power before running this.
 376         if(!_powerOnTimerSet) {
 377                 SetPowerOnTimer();
 378         }
 379
 380         // Check if an alarm timer has expired
 381         if(_alarmSet) {
 382                 if(_alarmTime.hr() == atoi(fgGetString("/instrumentation/clock/indicated-hour"))
 383                 && _alarmTime.min() == atoi(fgGetString("/instrumentation/clock/indicated-min"))) {
 384                         _messageStack.push_back("*Timer Expired");
 385                         _alarmSet = false;
 386                 }
 387         }
 388
 389         if(!_departed) {
 390                 if(_groundSpeed_kts > 30.0) {
 391                         _departed = true;
 392                         string th = fgGetString("/instrumentation/clock/indicated-hour");
 393                         string tm = fgGetString("/instrumentation/clock/indicated-min");
 394                         if(th.size() == 1) th = "0" + th;
 395                         if(tm.size() == 1) tm = "0" + tm;
 396                         _departureTimeString = th + tm;
 397                 }
 398         } else {
 399                 // TODO - check - is this prone to drift error over time?
 400                 // Should we difference the departure and current times?
 401                 // What about when the user resets the time of day from the menu?
 402                 _elapsedTime += dt;
 403         }
 404
 405         _time->update(_gpsLon * SG_DEGREES_TO_RADIANS, _gpsLat * SG_DEGREES_TO_RADIANS, 0, 0);
 406         // FIXME - currently all the below assumes leg mode and no DTO or OBS cancelled.
 407         if(_activeFP->IsEmpty()) {
 408                 // Not sure if we need to reset these each update or only when fp altered
 409                 _activeWaypoint.id.clear();
 410                 _navFlagged = true;
 411         } else if(_activeFP->waypoints.size() == 1) {
 412                 _activeWaypoint.id.clear();
 413         } else {
 414                 _navFlagged = false;
 415                 if(_activeWaypoint.id.empty() || _fromWaypoint.id.empty()) {
 416                         //cout << "Error, in leg mode with flightplan of 2 or more waypoints, but either active or from wp is NULL!\n";
 417                         OrientateToActiveFlightPlan();
 418                 }
 419
 420                 // Approach stuff
 421                 if(_approachLoaded) {
 422                         if(!_approachReallyArmed && !_approachActive) {
 423                                 // arm if within 30nm of airport.
 424                                 // TODO - let user cancel approach arm using external GPS-APR switch
 425                                 bool multi;
 426                                 const FGAirport* ap = FindFirstAptById(_approachID, multi, true);
 427                                 if(ap != NULL) {
 428                                         double d = GetGreatCircleDistance(_gpsLat, _gpsLon, ap->getLatitude() * SG_DEGREES_TO_RADIANS, ap->getLongitude() * SG_DEGREES_TO_RADIANS);
 429                                         if(d <= 30) {
 430                                                 _approachArm = true;
 431                                                 _approachReallyArmed = true;
 432                                                 _messageStack.push_back("*Press ALT To Set Baro");
 433                                                 // Not sure what we do if the user has already set CDI to 0.3 nm?
 434                                                 _targetCdiScaleIndex = 1;
 435                                                 if(_currentCdiScaleIndex == 1) {
 436                                                         // No problem!
 437                                                 } else if(_currentCdiScaleIndex == 0) {
 438                                                         _sourceCdiScaleIndex = 0;
 439                                                         _cdiScaleTransition = true;
 440                                                         _cdiTransitionTime = 30.0;
 441                                                         _currentCdiScale = _cdiScales[_currentCdiScaleIndex];
 442                                                 }
 443                                         }
 444                                 }
 445                         } else {
 446                                 // Check for approach active - we can only activate approach if it is really armed.
 447                                 if(_activeWaypoint.appType == GPS_FAF) {
 448                                         //cout << "Active waypoint is FAF, id is " << _activeWaypoint.id << '\n';
 449                                         if(GetGreatCircleDistance(_gpsLat, _gpsLon, _activeWaypoint.lat, _activeWaypoint.lon) <= 2.0 && !_obsMode) {
 450                                                 // Assume heading is OK for now
 451                                                 _approachArm = false;   // TODO - check - maybe arm is left on when actv comes on?
 452                                                 _approachReallyArmed = false;
 453                                                 _approachActive = true;
 454                                                 _targetCdiScaleIndex = 2;
 455                                                 if(_currentCdiScaleIndex == 2) {
 456                                                         // No problem!
 457                                                 } else if(_currentCdiScaleIndex == 1) {
 458                                                         _sourceCdiScaleIndex = 1;
 459                                                         _cdiScaleTransition = true;
 460                                                         _cdiTransitionTime = 30.0;      // TODO - compress it if time to FAF < 30sec
 461                                                         _currentCdiScale = _cdiScales[_currentCdiScaleIndex];
 462                                                 } else {
 463                                                         // Abort going active?
 464                                                         _approachActive = false;
 465                                                 }
 466                                         }
 467                                 }
 468                         }
 469                 }
 470
 471                 // CDI scale transition stuff
 472                 if(_cdiScaleTransition) {
 473                         if(fabs(_currentCdiScale - _cdiScales[_targetCdiScaleIndex]) < 0.001) {
 474                                 _currentCdiScale = _cdiScales[_targetCdiScaleIndex];
 475                                 _currentCdiScaleIndex = _targetCdiScaleIndex;
 476                                 _cdiScaleTransition = false;
 477                         } else {
 478                                 double scaleDiff = (_targetCdiScaleIndex > _sourceCdiScaleIndex
 479                                                     ? _cdiScales[_sourceCdiScaleIndex] - _cdiScales[_targetCdiScaleIndex]
 480                                                                         : _cdiScales[_targetCdiScaleIndex] - _cdiScales[_sourceCdiScaleIndex]);
 481                                 //cout << "ScaleDiff = " << scaleDiff << '\n';
 482                                 if(_targetCdiScaleIndex > _sourceCdiScaleIndex) {
 483                                         // Scaling down eg. 5nm -> 1nm
 484                                         _currentCdiScale -= (scaleDiff * dt / _cdiTransitionTime);
 485                                         if(_currentCdiScale < _cdiScales[_targetCdiScaleIndex]) {
 486                                                 _currentCdiScale = _cdiScales[_targetCdiScaleIndex];
 487                                                 _currentCdiScaleIndex = _targetCdiScaleIndex;
 488                                                 _cdiScaleTransition = false;
 489                                         }
 490                                 } else {
 491                                         _currentCdiScale += (scaleDiff * dt / _cdiTransitionTime);
 492                                         if(_currentCdiScale > _cdiScales[_targetCdiScaleIndex]) {
 493                                                 _currentCdiScale = _cdiScales[_targetCdiScaleIndex];
 494                                                 _currentCdiScaleIndex = _targetCdiScaleIndex;
 495                                                 _cdiScaleTransition = false;
 496                                         }
 497                                 }
 498                                 //cout << "_currentCdiScale = " << _currentCdiScale << '\n';
 499                         }
 500                 } else {
 501                         _currentCdiScale = _cdiScales[_currentCdiScaleIndex];
 502                 }
 503
 504
 505                 // Urgh - I've been setting the heading bug based on DTK,
 506                 // bug I think it should be based on heading re. active waypoint
 507                 // based on what the sim does after the final waypoint is passed.
 508                 // (DTK remains the same, but if track is held == DTK heading bug
 509                 // reverses to from once wp is passed).
 510                 /*
 511                 if(_fromWaypoint != NULL) {
 512                         // TODO - how do we handle the change of track with distance over long legs?
 513                         _dtkTrue = GetGreatCircleCourse(_fromWaypoint->lat, _fromWaypoint->lon, _activeWaypoint->lat, _activeWaypoint->lon) * SG_RADIANS_TO_DEGREES;
 514                         _dtkMag = GetMagHeadingFromTo(_fromWaypoint->lat, _fromWaypoint->lon, _activeWaypoint->lat, _activeWaypoint->lon);
 515                         // Don't change the heading bug if speed is too low otherwise it flickers to/from at rest
 516                         if(_groundSpeed_ms > 5) {
 517                                 //cout << "track = " << _track << ", dtk = " << _dtkTrue << '\n';
 518                                 double courseDev = _track - _dtkTrue;
 519                                 //cout << "courseDev = " << courseDev << ", normalized = ";
 520                                 SG_NORMALIZE_RANGE(courseDev, -180.0, 180.0);
 521                                 //cout << courseDev << '\n';
 522                                 _headingBugTo = (fabs(courseDev) > 90.0 ? false : true);
 523                         }
 524                 } else {
 525                         _dtkTrue = 0.0;
 526                         _dtkMag = 0.0;
 527                         // TODO - in DTO operation the position of initiation of DTO defines the "from waypoint".
 528                 }
 529                 */
 530                 if(!_activeWaypoint.id.empty()) {
 531                         double hdgTrue = GetGreatCircleCourse(_gpsLat, _gpsLon, _activeWaypoint.lat, _activeWaypoint.lon) * SG_RADIANS_TO_DEGREES;
 532                         if(_groundSpeed_ms > 5) {
 533                                 //cout << "track = " << _track << ", hdgTrue = " << hdgTrue << '\n';
 534                                 double courseDev = _track - hdgTrue;
 535                                 //cout << "courseDev = " << courseDev << ", normalized = ";
 536                                 SG_NORMALIZE_RANGE(courseDev, -180.0, 180.0);
 537                                 //cout << courseDev << '\n';
 538                                 _headingBugTo = (fabs(courseDev) > 90.0 ? false : true);
 539                         }
 540                         if(!_fromWaypoint.id.empty()) {
 541                                 _dtkTrue = GetGreatCircleCourse(_fromWaypoint.lat, _fromWaypoint.lon, _activeWaypoint.lat, _activeWaypoint.lon) * SG_RADIANS_TO_DEGREES;
 542                                 _dtkMag = GetMagHeadingFromTo(_fromWaypoint.lat, _fromWaypoint.lon, _activeWaypoint.lat, _activeWaypoint.lon);
 543                         } else {
 544                                 _dtkTrue = 0.0;
 545                                 _dtkMag = 0.0;
 546                         }
 547                 }
 548
 549                 _dist2Act = GetGreatCircleDistance(_gpsLat, _gpsLon, _activeWaypoint.lat, _activeWaypoint.lon) * SG_NM_TO_METER;
 550                 if(_groundSpeed_ms > 10.0) {
 551                         _eta = _dist2Act / _groundSpeed_ms;
 552                         if(_eta <= 36) {        // TODO - this is slightly different if turn anticipation is enabled.
 553                                 if(_headingBugTo) {
 554                                         _waypointAlert = true;  // TODO - not if the from flag is set.
 555                                 }
 556                         }
 557                         if(_eta < 60) {
 558                                 // Check if we should sequence to next leg.
 559                                 // Perhaps this should be done on distance instead, but 60s time (about 1 - 2 nm) seems reasonable for now.
 560                                 //double reverseHeading = GetGreatCircleCourse(_activeWaypoint->lat, _activeWaypoint->lon, _fromWaypoint->lat, _fromWaypoint->lon);
 561                                 // Hack - let's cheat and do it on heading bug for now.  TODO - that stops us 'cutting the corner'
 562                                 // when we happen to approach the inside turn of a waypoint - we should probably sequence at the midpoint
 563                                 // of the heading difference between legs in this instance.
 564                                 int idx = GetActiveWaypointIndex();
 565                                 bool finalLeg = (idx == (int)(_activeFP->waypoints.size()) - 1 ? true : false);
 566                                 bool finalDto = (_dto && idx == -1);    // Dto operation to a waypoint not in the flightplan - we don't sequence in this instance
 567                                 if(!_headingBugTo) {
 568                                         if(finalLeg) {
 569                                                 // Do nothing - not sure if Dto should switch off when arriving at the final waypoint of a flightplan
 570                                         } else if(finalDto) {
 571                                                 // Do nothing
 572                                         } else if(_activeWaypoint.appType == GPS_MAP) {
 573                                                 // Don't sequence beyond the missed approach point
 574                                                 //cout << "ACTIVE WAYPOINT is MAP - not sequencing!!!!!\n";
 575                                         } else {
 576                                                 //cout << "Sequencing...\n";
 577                                                 _fromWaypoint = _activeWaypoint;
 578                                                 _activeWaypoint = *_activeFP->waypoints[idx + 1];
 579                                                 _dto = false;
 580                                                 // TODO - course alteration message format is dependent on whether we are slaved HSI/CDI indicator or not.
 581                                                 // For now assume we are not.
 582                                                 string s;
 583                                                 if(fgGetBool("/instrumentation/nav[0]/slaved-to-gps")) {
 584                                                         // TODO - avoid the hardwiring on nav[0]
 585                                                         s = "Adj Nav Crs to ";
 586                                                 } else {
 587                                                         string s = "GPS Course is ";
 588                                                 }
 589                                                 double d = GetMagHeadingFromTo(_fromWaypoint.lat, _fromWaypoint.lon, _activeWaypoint.lat, _activeWaypoint.lon);
 590                                                 while(d < 0.0) d += 360.0;
 591                                                 while(d >= 360.0) d -= 360.0;
 592                                                 char buf[4];
 593                                                 snprintf(buf, 4, "%03i", (int)(d + 0.5));
 594                                                 s += buf;
 595                                                 _messageStack.push_back(s);
 596                                         }
 597                                         _waypointAlert = false;
 598                                 }
 599                         }
 600                 } else {
 601                         _eta = 0.0;
 602                 }
 603
 604                 /*
 605                 // First attempt at a sensible cross-track correction calculation
 606                 // Uh? - I think this is implemented further down the file!
 607                 if(_fromWaypoint != NULL) {
 608
 609                 } else {
 610                         _crosstrackDist = 0.0;
 611                 }
 612                 */
 613         }
 614 }
 615
 616 /*
 617         Expand a SIAP ident to the full procedure name (as shown on the approach chart).
 618         NOTE: Some of this is inferred from data, some is from documentation.
 619
 620         Example expansions from ARINC 424-18 [and the airport they're taken from]:
 621         "R10LY" <--> "RNAV (GPS) Y RWY 10 L"    [KBOI]
 622         "R10-Z" <--> "RNAV (GPS) Z RWY 10"              [KHTO]
 623         "S25"   <--> "VOR or GPS RWY 25"                [KHHR]
 624         "P20"   <--> "GPS RWY 20"                               [KDAN]
 625         "NDB-B" <--> "NDB or GPS-B"                             [KDAW]
 626         "NDBC"  <--> "NDB or GPS-C"                             [KEMT]
 627         "VDMA"  <--> "VOR/DME or GPS-A"                 [KDAW]
 628         "VDM-A" <--> "VOR/DME or GPS-A"                 [KEAG]
 629         "VDMB"  <--> "VOR/DME or GPS-B"                 [KDKX]
 630         "VORA"  <--> "VOR or GPS-A"                             [KEMT]
 631
 632         It seems that there are 2 basic types of expansions; those that include
 633         the runway and those that don't.  Of those that don't, it seems that 2
 634         different positions within the string to encode the identifying letter
 635         are used, i.e. with a dash and without.
 636 */
 637 string DCLGPS::ExpandSIAPIdent(const string& ident) {
 638         string name;
 639         bool has_rwy;
 640
 641         switch(ident[0]) {
 642         case 'N': name = "NDB or GPS"; has_rwy = false; break;
 643         case 'P': name = "GPS"; has_rwy = true; break;
 644         case 'R': name = "RNAV (GPS)"; has_rwy = true; break;
 645         case 'S': name = "VOR or GPS"; has_rwy = true; break;
 646         case 'V':
 647                 if(ident[1] == 'D') name = "VOR/DME or GPS";
 648                 else name = "VOR or GPS";
 649                 has_rwy = false;
 650                 break;
 651         default: // TODO output a log message
 652                 break;
 653         }
 654
 655         if(has_rwy) {
 656                 // Add the identifying letter if present
 657                 if(ident.size() == 5) {
 658                         name += ' ';
 659                         name += ident[4];
 660                 }
 661
 662                 // Add the runway
 663                 name += " RWY ";
 664                 name += ident.substr(1, 2);
 665
 666                 // Add a left/right/centre indication if present.
 667                 if(ident.size() > 3) {
 668                         if((ident[3] != '-') && (ident[3] != ' ')) {    // Early versions of the spec allowed a blank instead of a dash so check for both
 669                                 name += ' ';
 670                                 name += ident[3];
 671                         }
 672                 }
 673         } else {
 674                 // Add the identifying letter, which I *think* should always be present, but seems to be inconsistent as to whether a dash is used.
 675                 if(ident.size() == 5) {
 676                         name += '-';
 677                         name += ident[4];
 678                 } else if(ident.size() == 4) {
 679                         name += '-';
 680                         name += ident[3];
 681                 } else {
 682                         // No suffix letter
 683                 }
 684         }
 685
 686         return(name);
 687 }
 688
 689 GPSWaypoint* DCLGPS::GetActiveWaypoint() {
 690         return &_activeWaypoint;
 691 }
 692
 693 // Returns meters
 694 float DCLGPS::GetDistToActiveWaypoint() {
 695         return _dist2Act;
 696 }
 697
 698 // I don't yet fully understand all the gotchas about where to source time from.
 699 // This function sets the initial timer before the clock exports properties
 700 // and the one below uses the clock to be consistent with the rest of the code.
 701 // It might change soonish...
 702 void DCLGPS::SetPowerOnTimer() {
 703         struct tm *t = globals->get_time_params()->getGmt();
 704         _powerOnTime.set_hr(t->tm_hour);
 705         _powerOnTime.set_min(t->tm_min);
 706         _powerOnTimerSet = true;
 707 }
 708
 709 void DCLGPS::ResetPowerOnTimer() {
 710         _powerOnTime.set_hr(atoi(fgGetString("/instrumentation/clock/indicated-hour")));
 711         _powerOnTime.set_min(atoi(fgGetString("/instrumentation/clock/indicated-min")));
 712         _powerOnTimerSet = true;
 713 }
 714
 715 double DCLGPS::GetCDIDeflection() const {
 716         double xtd = CalcCrossTrackDeviation(); //nm
 717         return((xtd / _currentCdiScale) * 5.0 * 2.5 * -1.0);
 718 }
 719
 720 void DCLGPS::DtoInitiate(const string& s) {
 721         //cout << "DtoInitiate, s = " << s << '\n';
 722         const GPSWaypoint* wp = FindFirstByExactId(s);
 723         if(wp) {
 724                 //cout << "Waypoint found, starting dto operation!\n";
 725                 _dto = true;
 726                 _activeWaypoint = *wp;
 727                 _fromWaypoint.lat = _gpsLat;
 728                 _fromWaypoint.lon = _gpsLon;
 729                 _fromWaypoint.type = GPS_WP_VIRT;
 730                 _fromWaypoint.id = "DTOWP";
 731     delete wp;
 732         } else {
 733                 //cout << "Waypoint not found, ignoring dto request\n";
 734                 // Should bring up the user waypoint page, but we're not implementing that yet.
 735                 _dto = false;   // TODO - implement this some day.
 736         }
 737 }
 738
 739 void DCLGPS::DtoCancel() {
 740         if(_dto) {
 741                 // i.e. don't bother reorientating if we're just cancelling a DTO button press
 742                 // without having previously initiated DTO.
 743                 OrientateToActiveFlightPlan();
 744         }
 745         _dto = false;
 746 }
 747
 748 void DCLGPS::ToggleOBSMode() {
 749         _obsMode = !_obsMode;
 750         if(_obsMode) {
 751                 if(!_activeWaypoint.id.empty()) {
 752                         _obsHeading = static_cast<int>(_dtkMag);
 753                 }
 754                 // TODO - the _fromWaypoint location will change as the OBS heading changes.
 755                 // Might need to store the OBS initiation position somewhere in case it is needed again.
 756                 SetOBSFromWaypoint();
 757         }
 758 }
 759
 760 // Set the _fromWaypoint position based on the active waypoint and OBS radial.
 761 void DCLGPS::SetOBSFromWaypoint() {
 762         if(!_obsMode) return;
 763         if(_activeWaypoint.id.empty()) return;
 764
 765         // TODO - base the 180 deg correction on the to/from flag.
 766         _fromWaypoint = GetPositionOnMagRadial(_activeWaypoint, 10, _obsHeading + 180.0);
 767         _fromWaypoint.id = "OBSWP";
 768 }
 769
 770 void DCLGPS::CDIFSDIncrease() {
 771         if(_currentCdiScaleIndex == 0) {
 772                 _currentCdiScaleIndex = _cdiScales.size() - 1;
 773         } else {
 774                 _currentCdiScaleIndex--;
 775         }
 776 }
 777
 778 void DCLGPS::CDIFSDDecrease() {
 779         _currentCdiScaleIndex++;
 780         if(_currentCdiScaleIndex == _cdiScales.size()) {
 781                 _currentCdiScaleIndex = 0;
 782         }
 783 }
 784
 785 void DCLGPS::DrawChar(char c, int field, int px, int py, bool bold) {
 786 }
 787
 788 void DCLGPS::DrawText(const string& s, int field, int px, int py, bool bold) {
 789 }
 790
 791 void DCLGPS::SetBaroUnits(int n, bool wrap) {
 792         if(n < 1) {
 793                 _baroUnits = (GPSPressureUnits)(wrap ? 3 : 1);
 794         } else if(n > 3) {
 795                 _baroUnits = (GPSPressureUnits)(wrap ? 1 : 3);
 796         } else {
 797                 _baroUnits = (GPSPressureUnits)n;
 798         }
 799 }
 800
 801 void DCLGPS::CreateDefaultFlightPlans() {}
 802
 803 // Get the time to the active waypoint in seconds.
 804 // Returns -1 if groundspeed < 30 kts
 805 double DCLGPS::GetTimeToActiveWaypoint() {
 806         if(_groundSpeed_kts < 30.0) {
 807                 return(-1.0);
 808         } else {
 809                 return(_eta);
 810         }
 811 }
 812
 813 // Get the time to the final waypoint in seconds.
 814 // Returns -1 if groundspeed < 30 kts
 815 double DCLGPS::GetETE() {
 816         if(_groundSpeed_kts < 30.0) {
 817                 return(-1.0);
 818         } else {
 819                 // TODO - handle OBS / DTO operation appropriately
 820                 if(_activeFP->waypoints.empty()) {
 821                         return(-1.0);
 822                 } else {
 823                         return(GetTimeToWaypoint(_activeFP->waypoints[_activeFP->waypoints.size() - 1]->id));
 824                 }
 825         }
 826 }
 827
 828 // Get the time to a given waypoint (spec'd by ID) in seconds.
 829 // returns -1 if groundspeed is less than 30kts.
 830 // If the waypoint is an unreached part of the active flight plan the time will be via each leg.
 831 // otherwise it will be a direct-to time.
 832 double DCLGPS::GetTimeToWaypoint(const string& id) {
 833         if(_groundSpeed_kts < 30.0) {
 834                 return(-1.0);
 835         }
 836
 837         double eta = 0.0;
 838         int n1 = GetActiveWaypointIndex();
 839         int n2 = GetWaypointIndex(id);
 840         if(n2 > n1) {
 841                 eta = _eta;
 842                 for(unsigned int i=n1+1; i<_activeFP->waypoints.size(); ++i) {
 843                         GPSWaypoint* wp1 = _activeFP->waypoints[i-1];
 844                         GPSWaypoint* wp2 = _activeFP->waypoints[i];
 845                         double distm = GetGreatCircleDistance(wp1->lat, wp1->lon, wp2->lat, wp2->lon) * SG_NM_TO_METER;
 846                         eta += (distm / _groundSpeed_ms);
 847                 }
 848                 return(eta);
 849         } else if(id == _activeWaypoint.id) {
 850                 return(_eta);
 851         } else {
 852                 const GPSWaypoint* wp = FindFirstByExactId(id);
 853                 if(wp == NULL) return(-1.0);
 854                 double distm = GetGreatCircleDistance(_gpsLat, _gpsLon, wp->lat, wp->lon);
 855     delete wp;
 856                 return(distm / _groundSpeed_ms);
 857         }
 858         return(-1.0);   // Hopefully we never get here!
 859 }
 860
 861 // Returns magnetic great-circle heading
 862 // TODO - document units.
 863 float DCLGPS::GetHeadingToActiveWaypoint() {
 864         if(_activeWaypoint.id.empty()) {
 865                 return(-888);
 866         } else {
 867                 double h = GetMagHeadingFromTo(_gpsLat, _gpsLon, _activeWaypoint.lat, _activeWaypoint.lon);
 868                 while(h <= 0.0) h += 360.0;
 869                 while(h > 360.0) h -= 360.0;
 870                 return((float)h);
 871         }
 872 }
 873
 874 // Returns magnetic great-circle heading
 875 // TODO - what units?
 876 float DCLGPS::GetHeadingFromActiveWaypoint() {
 877         if(_activeWaypoint.id.empty()) {
 878                 return(-888);
 879         } else {
 880                 double h = GetMagHeadingFromTo(_activeWaypoint.lat, _activeWaypoint.lon, _gpsLat, _gpsLon);
 881                 while(h <= 0.0) h += 360.0;
 882                 while(h > 360.0) h -= 360.0;
 883                 return(h);
 884         }
 885 }
 886
 887 void DCLGPS::ClearFlightPlan(int n) {
 888         for(unsigned int i=0; i<_flightPlans[n]->waypoints.size(); ++i) {
 889                 delete _flightPlans[n]->waypoints[i];
 890         }
 891         _flightPlans[n]->waypoints.clear();
 892 }
 893
 894 void DCLGPS::ClearFlightPlan(GPSFlightPlan* fp) {
 895         for(unsigned int i=0; i<fp->waypoints.size(); ++i) {
 896                 delete fp->waypoints[i];
 897         }
 898         fp->waypoints.clear();
 899 }
 900
 901 int DCLGPS::GetActiveWaypointIndex() {
 902         for(unsigned int i=0; i<_flightPlans[0]->waypoints.size(); ++i) {
 903                 if(_flightPlans[0]->waypoints[i]->id == _activeWaypoint.id) return((int)i);
 904         }
 905         return(-1);
 906 }
 907
 908 int DCLGPS::GetWaypointIndex(const string& id) {
 909         for(unsigned int i=0; i<_flightPlans[0]->waypoints.size(); ++i) {
 910                 if(_flightPlans[0]->waypoints[i]->id == id) return((int)i);
 911         }
 912         return(-1);
 913 }
 914
 915 void DCLGPS::OrientateToFlightPlan(GPSFlightPlan* fp) {
 916         //cout << "Orientating...\n";
 917         //cout << "_lat = " << _lat << ", _lon = " << _lon << ", _gpsLat = " << _gpsLat << ", gpsLon = " << _gpsLon << '\n';
 918         if(fp->IsEmpty()) {
 919                 _activeWaypoint.id.clear();
 920                 _navFlagged = true;
 921         } else {
 922                 _navFlagged = false;
 923                 if(fp->waypoints.size() == 1) {
 924                         // TODO - may need to flag nav here if not dto or obs, or possibly handle it somewhere else.
 925                         _activeWaypoint = *fp->waypoints[0];
 926                         _fromWaypoint.id.clear();
 927                 } else {
 928                         // FIXME FIXME FIXME
 929                         _fromWaypoint = *fp->waypoints[0];
 930                         _activeWaypoint = *fp->waypoints[1];
 931                         double dmin = 1000000;  // nm!!
 932                         // For now we will simply start on the leg closest to our current position.
 933                         // It's possible that more fancy algorithms may take either heading or track
 934                         // into account when setting inital leg - I'm not sure.
 935                         // This method should handle most cases perfectly OK though.
 936                         for(unsigned int i = 1; i < fp->waypoints.size(); ++i) {
 937                                 //cout << "Pass " << i << ", dmin = " << dmin << ", leg is " << fp->waypoints[i-1]->id << " to " << fp->waypoints[i]->id << '\n';
 938                                 // First get the cross track correction.
 939                                 double d0 = fabs(CalcCrossTrackDeviation(*fp->waypoints[i-1], *fp->waypoints[i]));
 940                                 // That is the shortest distance away we could be though - check for
 941                                 // longer distances if we are 'off the end' of the leg.
 942                                 double ht1 = GetGreatCircleCourse(fp->waypoints[i-1]->lat, fp->waypoints[i-1]->lon,
 943                                                                   fp->waypoints[i]->lat, fp->waypoints[i]->lon)
 944                                                                                                   * SG_RADIANS_TO_DEGREES;
 945                                 // not simply the reverse of the above due to great circle navigation.
 946                                 double ht2 = GetGreatCircleCourse(fp->waypoints[i]->lat, fp->waypoints[i]->lon,
 947                                                                   fp->waypoints[i-1]->lat, fp->waypoints[i-1]->lon)
 948                                                                                                   * SG_RADIANS_TO_DEGREES;
 949                                 double hw1 = GetGreatCircleCourse(_gpsLat, _gpsLon,
 950                                                                   fp->waypoints[i]->lat, fp->waypoints[i]->lon)
 951                                                                                                   * SG_RADIANS_TO_DEGREES;
 952                                 double hw2 = GetGreatCircleCourse(_gpsLat, _gpsLon,
 953                                                                   fp->waypoints[i-1]->lat, fp->waypoints[i-1]->lon)
 954                                                                                                   * SG_RADIANS_TO_DEGREES;
 955                                 double h1 = ht1 - hw1;
 956                                 double h2 = ht2 - hw2;
 957                                 //cout << "d0, h1, h2 = " << d0 << ", " << h1 << ", " << h2 << '\n';
 958                                 //cout << "Normalizing...\n";
 959                                 SG_NORMALIZE_RANGE(h1, -180.0, 180.0);
 960                                 SG_NORMALIZE_RANGE(h2, -180.0, 180.0);
 961                                 //cout << "d0, h1, h2 = " << d0 << ", " << h1 << ", " << h2 << '\n';
 962                                 if(fabs(h1) > 90.0) {
 963                                         // We are past the end of the to waypoint
 964                                         double d = GetGreatCircleDistance(_gpsLat, _gpsLon, fp->waypoints[i]->lat, fp->waypoints[i]->lon);
 965                                         if(d > d0) d0 = d;
 966                                         //cout << "h1 triggered, d0 now = " << d0 << '\n';
 967                                 } else if(fabs(h2) > 90.0) {
 968                                         // We are past the end (not yet at!) the from waypoint
 969                                         double d = GetGreatCircleDistance(_gpsLat, _gpsLon, fp->waypoints[i-1]->lat, fp->waypoints[i-1]->lon);
 970                                         if(d > d0) d0 = d;
 971                                         //cout << "h2 triggered, d0 now = " << d0 << '\n';
 972                                 }
 973                                 if(d0 < dmin) {
 974                                         //cout << "THIS LEG NOW ACTIVE!\n";
 975                                         dmin = d0;
 976                                         _fromWaypoint = *fp->waypoints[i-1];
 977                                         _activeWaypoint = *fp->waypoints[i];
 978                                 }
 979                         }
 980                 }
 981         }
 982 }
 983
 984 void DCLGPS::OrientateToActiveFlightPlan() {
 985         OrientateToFlightPlan(_activeFP);
 986 }
 987
 988 /***************************************/
 989
 990 // Utility function - create a flightplan from a list of waypoint ids and types
 991 void DCLGPS::CreateFlightPlan(GPSFlightPlan* fp, vector<string> ids, vector<GPSWpType> wps) {
 992         if(fp == NULL) fp = new GPSFlightPlan;
 993         unsigned int i;
 994         if(!fp->waypoints.empty()) {
 995                 for(i=0; i<fp->waypoints.size(); ++i) {
 996                         delete fp->waypoints[i];
 997                 }
 998                 fp->waypoints.clear();
 999         }
1000         if(ids.size() != wps.size()) {
1001                 cout << "ID and Waypoint types list size mismatch in GPS::CreateFlightPlan - no flightplan created!\n";
1002                 return;
1003         }
1004         for(i=0; i<ids.size(); ++i) {
1005                 bool multi;
1006                 const FGAirport* ap;
1007                 FGNavRecord* np;
1008                 GPSWaypoint* wp = new GPSWaypoint;
1009                 wp->type = wps[i];
1010                 switch(wp->type) {
1011                 case GPS_WP_APT:
1012                         ap = FindFirstAptById(ids[i], multi, true);
1013                         if(ap == NULL) {
1014                                 // error
1015                                 delete wp;
1016                         } else {
1017                                 wp->lat = ap->getLatitude() * SG_DEGREES_TO_RADIANS;
1018                                 wp->lon = ap->getLongitude() * SG_DEGREES_TO_RADIANS;
1019                                 wp->id = ids[i];
1020                                 fp->waypoints.push_back(wp);
1021                         }
1022                         break;
1023                 case GPS_WP_VOR:
1024                         np = FindFirstVorById(ids[i], multi, true);
1025                         if(np == NULL) {
1026                                 // error
1027                                 delete wp;
1028                         } else {
1029                                 wp->lat = np->get_lat() * SG_DEGREES_TO_RADIANS;
1030                                 wp->lon = np->get_lon() * SG_DEGREES_TO_RADIANS;
1031                                 wp->id = ids[i];
1032                                 fp->waypoints.push_back(wp);
1033                         }
1034                         break;
1035                 case GPS_WP_NDB:
1036                         np = FindFirstNDBById(ids[i], multi, true);
1037                         if(np == NULL) {
1038                                 // error
1039                                 delete wp;
1040                         } else {
1041                                 wp->lat = np->get_lat() * SG_DEGREES_TO_RADIANS;
1042                                 wp->lon = np->get_lon() * SG_DEGREES_TO_RADIANS;
1043                                 wp->id = ids[i];
1044                                 fp->waypoints.push_back(wp);
1045                         }
1046                         break;
1047                 case GPS_WP_INT:
1048                         // TODO TODO
1049                         break;
1050                 case GPS_WP_USR:
1051                         // TODO
1052                         break;
1053                 case GPS_WP_VIRT:
1054                         // TODO
1055                         break;
1056                 }
1057         }
1058 }
1059
1060 /***************************************/
1061
1062 class DCLGPSFilter : public FGPositioned::Filter
1063 {
1064 public:
1065   virtual bool pass(const FGPositioned* aPos) const {
1066     switch (aPos->type()) {
1067     case FGPositioned::AIRPORT:
1068     // how about heliports and seaports?
1069     case FGPositioned::NDB:
1070     case FGPositioned::VOR:
1071     case FGPositioned::WAYPOINT:
1072     case FGPositioned::FIX:
1073       break;
1074     default: return false; // reject all other types
1075     }
1076     return true;
1077   }
1078 };
1079
1080 GPSWaypoint* DCLGPS::FindFirstById(const string& id) const
1081 {
1082   DCLGPSFilter filter;
1083   FGPositionedRef result = FGPositioned::findNextWithPartialId(NULL, id, &filter);
1084   return GPSWaypoint::createFromPositioned(result);
1085 }
1086
1087 GPSWaypoint* DCLGPS::FindFirstByExactId(const string& id) const
1088 {
1089   SGGeod pos(SGGeod::fromRad(_lon, _lat));
1090   FGPositionedRef result = FGPositioned::findClosestWithIdent(id, pos);
1091   return GPSWaypoint::createFromPositioned(result);
1092 }
1093
1094 // TODO - add the ASCII / alphabetical stuff from the Atlas version
1095 FGPositioned* DCLGPS::FindTypedFirstById(const string& id, FGPositioned::Type ty, bool &multi, bool exact)
1096 {
1097   multi = false;
1098   FGPositioned::TypeFilter filter(ty);
1099
1100   if (exact) {
1101     FGPositioned::List matches =
1102       FGPositioned::findAllWithIdentSortedByRange(id, SGGeod::fromRad(_lon, _lat), &filter);
1103     multi = (matches.size() > 1);
1104     return matches.empty() ? NULL : matches.front().ptr();
1105   }
1106
1107   return FGPositioned::findNextWithPartialId(NULL, id, &filter);
1108 }
1109
1110 FGNavRecord* DCLGPS::FindFirstVorById(const string& id, bool &multi, bool exact)
1111 {
1112   return dynamic_cast<FGNavRecord*>(FindTypedFirstById(id, FGPositioned::VOR, multi, exact));
1113 }
1114
1115 FGNavRecord* DCLGPS::FindFirstNDBById(const string& id, bool &multi, bool exact)
1116 {
1117   return dynamic_cast<FGNavRecord*>(FindTypedFirstById(id, FGPositioned::NDB, multi, exact));
1118 }
1119
1120 const FGFix* DCLGPS::FindFirstIntById(const string& id, bool &multi, bool exact)
1121 {
1122   return dynamic_cast<FGFix*>(FindTypedFirstById(id, FGPositioned::FIX, multi, exact));
1123 }
1124
1125 const FGAirport* DCLGPS::FindFirstAptById(const string& id, bool &multi, bool exact)
1126 {
1127   return dynamic_cast<FGAirport*>(FindTypedFirstById(id, FGPositioned::AIRPORT, multi, exact));
1128 }
1129
1130 FGNavRecord* DCLGPS::FindClosestVor(double lat_rad, double lon_rad) {
1131   FGPositioned::TypeFilter filter(FGPositioned::VOR);
1132   double cutoff = 1000; // nautical miles
1133   FGPositionedRef v = FGPositioned::findClosest(SGGeod::fromRad(lon_rad, lat_rad), cutoff, &filter);
1134   if (!v) {
1135     return NULL;
1136   }
1137
1138   return dynamic_cast<FGNavRecord*>(v.ptr());
1139 }
1140
1141 //----------------------------------------------------------------------------------------------------------
1142
1143 // Takes lat and lon in RADIANS!!!!!!!
1144 double DCLGPS::GetMagHeadingFromTo(double latA, double lonA, double latB, double lonB) {
1145         double h = GetGreatCircleCourse(latA, lonA, latB, lonB);
1146         h *= SG_RADIANS_TO_DEGREES;
1147         // TODO - use the real altitude below instead of 0.0!
1148         //cout << "MagVar = " << sgGetMagVar(_gpsLon, _gpsLat, 0.0, _time->getJD()) * SG_RADIANS_TO_DEGREES << '\n';
1149         h -= sgGetMagVar(_gpsLon, _gpsLat, 0.0, _time->getJD()) * SG_RADIANS_TO_DEGREES;
1150         while(h >= 360.0) h -= 360.0;
1151         while(h < 0.0) h += 360.0;
1152         return(h);
1153 }
1154
1155 // ---------------- Great Circle formulae from "The Aviation Formulary" -------------
1156 // Note that all of these assume that the world is spherical.
1157
1158 double Rad2Nm(double theta) {
1159         return(((180.0*60.0)/SG_PI)*theta);
1160 }
1161
1162 double Nm2Rad(double d) {
1163         return((SG_PI/(180.0*60.0))*d);
1164 }
1165
1166 /* QUOTE:
1167
1168 The great circle distance d between two points with coordinates {lat1,lon1} and {lat2,lon2} is given by:
1169
1170 d=acos(sin(lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(lon1-lon2))
1171
1172 A mathematically equivalent formula, which is less subject to rounding error for short distances is:
1173
1174 d=2*asin(sqrt((sin((lat1-lat2)/2))^2 +
1175                  cos(lat1)*cos(lat2)*(sin((lon1-lon2)/2))^2))
1176
1177 */
1178
1179 // Returns distance in nm, takes lat & lon in RADIANS
1180 double DCLGPS::GetGreatCircleDistance(double lat1, double lon1, double lat2, double lon2) const {
1181         double d = 2.0 * asin(sqrt(((sin((lat1-lat2)/2.0))*(sin((lat1-lat2)/2.0))) +
1182                    cos(lat1)*cos(lat2)*(sin((lon1-lon2)/2.0))*(sin((lon1-lon2)/2.0))));
1183         return(Rad2Nm(d));
1184 }
1185
1186 // fmod dosen't do what we want :-(
1187 static double mod(double d1, double d2) {
1188         return(d1 - d2*floor(d1/d2));
1189 }
1190
1191 // Returns great circle course from point 1 to point 2
1192 // Input and output in RADIANS.
1193 double DCLGPS::GetGreatCircleCourse (double lat1, double lon1, double lat2, double lon2) const {
1194         //double h = 0.0;
1195         /*
1196         // Special case the poles
1197         if(cos(lat1) < SG_EPSILON) {
1198                 if(lat1 > 0) {
1199                         // Starting from North Pole
1200                         h = SG_PI;
1201                 } else {
1202                         // Starting from South Pole
1203                         h = 2.0 * SG_PI;
1204                 }
1205         } else {
1206                 // Urgh - the formula below is for negative lon +ve !!!???
1207                 double d = GetGreatCircleDistance(lat1, lon1, lat2, lon2);
1208                 cout << "d = " << d;
1209                 d = Nm2Rad(d);
1210                 //cout << ", d_theta = " << d;
1211                 //cout << ", and d = " << Rad2Nm(d) << ' ';
1212                 if(sin(lon2 - lon1) < 0) {
1213                         cout << " A ";
1214                         h = acos((sin(lat2)-sin(lat1)*cos(d))/(sin(d)*cos(lat1)));
1215                 } else {
1216                         cout << " B ";
1217                         h = 2.0 * SG_PI - acos((sin(lat2)-sin(lat1)*cos(d))/(sin(d)*cos(lat1)));
1218                 }
1219         }
1220         cout << h * SG_RADIANS_TO_DEGREES << '\n';
1221         */
1222
1223         return( mod(atan2(sin(lon2-lon1)*cos(lat2),
1224             cos(lat1)*sin(lat2)-sin(lat1)*cos(lat2)*cos(lon2-lon1)),
1225             2.0*SG_PI) );
1226 }
1227
1228 // Return a position on a radial from wp1 given distance d (nm) and magnetic heading h (degrees)
1229 // Note that d should be less that 1/4 Earth diameter!
1230 GPSWaypoint DCLGPS::GetPositionOnMagRadial(const GPSWaypoint& wp1, double d, double h) {
1231         h += sgGetMagVar(wp1.lon, wp1.lat, 0.0, _time->getJD()) * SG_RADIANS_TO_DEGREES;
1232         return(GetPositionOnRadial(wp1, d, h));
1233 }
1234
1235 // Return a position on a radial from wp1 given distance d (nm) and TRUE heading h (degrees)
1236 // Note that d should be less that 1/4 Earth diameter!
1237 GPSWaypoint DCLGPS::GetPositionOnRadial(const GPSWaypoint& wp1, double d, double h) {
1238         while(h < 0.0) h += 360.0;
1239         while(h > 360.0) h -= 360.0;
1240
1241         h *= SG_DEGREES_TO_RADIANS;
1242         d *= (SG_PI / (180.0 * 60.0));
1243
1244         double lat=asin(sin(wp1.lat)*cos(d)+cos(wp1.lat)*sin(d)*cos(h));
1245         double lon;
1246         if(cos(lat)==0) {
1247                 lon=wp1.lon;      // endpoint a pole
1248         } else {
1249                 lon=mod(wp1.lon+asin(sin(h)*sin(d)/cos(lat))+SG_PI,2*SG_PI)-SG_PI;
1250         }
1251
1252         GPSWaypoint wp;
1253         wp.lat = lat;
1254         wp.lon = lon;
1255         wp.type = GPS_WP_VIRT;
1256         return(wp);
1257 }
1258
1259 // Returns cross-track deviation in Nm.
1260 double DCLGPS::CalcCrossTrackDeviation() const {
1261         return(CalcCrossTrackDeviation(_fromWaypoint, _activeWaypoint));
1262 }
1263
1264 // Returns cross-track deviation of the current position between two arbitary waypoints in nm.
1265 double DCLGPS::CalcCrossTrackDeviation(const GPSWaypoint& wp1, const GPSWaypoint& wp2) const {
1266         //if(wp1 == NULL || wp2 == NULL) return(0.0);
1267         if(wp1.id.empty() || wp2.id.empty()) return(0.0);
1268         double xtd = asin(sin(Nm2Rad(GetGreatCircleDistance(wp1.lat, wp1.lon, _gpsLat, _gpsLon)))
1269                           * sin(GetGreatCircleCourse(wp1.lat, wp1.lon, _gpsLat, _gpsLon) - GetGreatCircleCourse(wp1.lat, wp1.lon, wp2.lat, wp2.lon)));
1270         return(Rad2Nm(xtd));
1271 }