src/ATCDCL/ground.cxx

   1 // FGGround - a class to provide ground control at larger airports.
   2 //
   3 // Written by David Luff, started March 2002.
   4 //
   5 // Copyright (C) 2002  David C. Luff - david.luff@nottingham.ac.uk
   6 //
   7 // This program is free software; you can redistribute it and/or
   8 // modify it under the terms of the GNU General Public License as
   9 // published by the Free Software Foundation; either version 2 of the
  10 // License, or (at your option) any later version.
  11 //
  12 // This program is distributed in the hope that it will be useful, but
  13 // WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 // General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License
  18 // along with this program; if not, write to the Free Software
  19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  20
  21 #ifdef HAVE_CONFIG_H
  22 #  include <config.h>
  23 #endif
  24
  25 #include <iostream>
  26
  27 #include <simgear/misc/sg_path.hxx>
  28 #include <simgear/math/sg_random.h>
  29 #include <simgear/debug/logstream.hxx>
  30 #include <simgear/misc/sgstream.hxx>
  31 #include <simgear/constants.h>
  32 #include <Main/globals.hxx>
  33
  34 #include <stdlib.h>
  35 #include <fstream>
  36
  37 #include "ground.hxx"
  38 #include "ATCutils.hxx"
  39 #include "AILocalTraffic.hxx"
  40 #include "ATCmgr.hxx"
  41
  42 using std::ifstream;
  43 using std::cout;
  44
  45 node::node() {
  46 }
  47
  48 node::~node() {
  49         for(unsigned int i=0; i < arcs.size(); ++i) {
  50                 delete arcs[i];
  51         }
  52 }
  53
  54 // Make sure that a_path.cost += distance is safe from the moment it's created.
  55 a_path::a_path() {
  56         cost = 0;
  57 }
  58
  59 FGGround::FGGround() {
  60         ATCmgr = globals->get_ATC_mgr();
  61         _type = GROUND;
  62         networkLoadOK = false;
  63         ground_traffic.erase(ground_traffic.begin(), ground_traffic.end());
  64         ground_traffic_itr = ground_traffic.begin();
  65
  66         // Init the property nodes - TODO - need to make sure we're getting surface winds.
  67         wind_from_hdg = fgGetNode("/environment/wind-from-heading-deg", true);
  68         wind_speed_knots = fgGetNode("/environment/wind-speed-kt", true);
  69
  70         // TODO - get the actual airport elevation
  71         aptElev = 0.0;
  72 }
  73
  74 FGGround::FGGround(const string& id) {
  75         ATCmgr = globals->get_ATC_mgr();
  76         networkLoadOK = false;
  77         ground_traffic.erase(ground_traffic.begin(), ground_traffic.end());
  78         ground_traffic_itr = ground_traffic.begin();
  79         ident = id;
  80
  81         // Init the property nodes - TODO - need to make sure we're getting surface winds.
  82         wind_from_hdg = fgGetNode("/environment/wind-from-heading-deg", true);
  83         wind_speed_knots = fgGetNode("/environment/wind-speed-kt", true);
  84
  85         // TODO - get the actual airport elevation
  86         aptElev = 0.0;
  87 }
  88
  89 FGGround::~FGGround() {
  90 }
  91
  92 void FGGround::ParseRwyExits(node* np, char* es) {
  93         char* token;
  94         char estr[20];
  95         strcpy(estr, es);
  96         const char delimiters[] = "-";
  97         token = strtok(estr, delimiters);
  98         while(token != NULL) {
  99                 int i = atoi(token);
 100                 //cout << "token = " << token << endl;
 101                 //cout << "rwy number = " << i << endl;
 102                 //runways[(atoi(token))].exits.push_back(np);
 103                 runways[i].exits.push_back(np);
 104                 //cout << "token = " << token << '\n';
 105                 token = strtok(NULL, delimiters);
 106         }
 107 }
 108
 109
 110 // Load the ground logical network of the current instances airport
 111 // Return true if successfull.
 112 // TODO - currently the file is assumed to reside in the base/ATC directory.
 113 // This might change to something more thought out in the future.
 114 // NOTE - currently it is assumed that all nodes are loaded before any arcs.
 115 // It won't work ATM if this doesn't hold true.
 116 bool FGGround::LoadNetwork() {
 117         node* np;
 118         arc* ap;
 119         Gate* gp;
 120
 121         int gateCount = 0;      // This is used to allocate gateID's from zero upwards
 122         // This may well change in the future - probably to reading in the real-world
 123         // gate numbers from file.
 124
 125         ifstream fin;
 126         SGPath path = globals->get_fg_root();
 127         //string taxiPath = "ATC/" + ident + ".taxi";
 128         string taxiPath = "ATC/KEMT.taxi";      // FIXME - HARDWIRED FOR TESTING
 129         path.append(taxiPath);
 130
 131         SG_LOG(SG_ATC, SG_INFO, "Trying to read taxiway data for " << ident << "...");
 132         //cout << "Trying to read taxiway data for " << ident << "..." << endl;
 133         fin.open(path.c_str(), ios::in);
 134         if(!fin) {
 135                 SG_LOG(SG_ATC, SG_ALERT, "Unable to open taxiway data input file " << path.c_str());
 136                 //cout << "Unable to open taxiway data input file " << path.c_str() << endl;
 137                 return(false);
 138         }
 139
 140         char ch;
 141         char buf[30];
 142         while(!fin.eof()) {
 143                 fin >> buf;
 144                 // Node, arc, or [End]?
 145                 //cout << "Read in ground network element type = " << buf << endl;
 146                 if(!strcmp(buf, "[End]")) {             // TODO - maybe make this more robust to spelling errors by just looking for '['
 147                         SG_LOG(SG_ATC, SG_INFO, "Done reading " << path.c_str() << endl);
 148                         break;
 149                 } else if(!strcmp(buf, "N")) {
 150                         // Node
 151                         np = new node;
 152                         np->struct_type = NODE;
 153                         fin >> buf;
 154                         np->nodeID = atoi(buf);
 155                         fin >> buf;
 156                         np->pos.setLongitudeDeg(atof(buf));
 157                         fin >> buf;
 158                         np->pos.setLatitudeDeg(atof(buf));
 159                         fin >> buf;
 160                         np->pos.setElevationM(atof(buf));
 161                         fin >> buf;             // node type
 162                         if(!strcmp(buf, "J")) {
 163                                 np->type = JUNCTION;
 164                         } else if(!strcmp(buf, "T")) {
 165                                 np->type = TJUNCTION;
 166                         } else if(!strcmp(buf, "H")) {
 167                                 np->type = HOLD;
 168                         } else {
 169                                 SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown node type in taxi network...\n");
 170                                 delete np;
 171                                 return(false);
 172                         }
 173                         fin >> buf;             // rwy exit information - gets parsed later - FRAGILE - will break if buf is reused.
 174                         // Now the name
 175                         fin >> ch;      // strip the leading " off
 176                         np->name = "";
 177                         while(1) {
 178                                 fin.unsetf(ios::skipws);
 179                                 fin >> ch;
 180                                 if((ch == '"') || (ch == 0x0A)) {
 181                                         break;
 182                                 }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
 183                                 np->name += ch;
 184                         }
 185                         fin.setf(ios::skipws);
 186                         network.push_back(np);
 187                         // FIXME - fragile - replies on buf not getting modified from exits read to here
 188                         // see if we also need to push it onto the runway exit list
 189                         //cout << "strlen(buf) = " << strlen(buf) << endl;
 190                         if(strlen(buf) > 2) {
 191                                 //cout << "Calling ParseRwyExits for " << buf << endl;
 192                                 ParseRwyExits(np, buf);
 193                         }
 194                 } else if(!strcmp(buf, "A")) {
 195                         ap = new arc;
 196                         ap->struct_type = ARC;
 197                         fin >> buf;
 198                         ap->n1 = atoi(buf);
 199                         fin >> buf;
 200                         ap->n2 = atoi(buf);
 201                         fin >> buf;
 202                         if(!strcmp(buf, "R")) {
 203                                 ap->type = RUNWAY;
 204                         } else if(!strcmp(buf, "T")) {
 205                                 ap->type = TAXIWAY;
 206                         } else {
 207                                 SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown arc type in taxi network...\n");
 208                                 delete ap;
 209                                 return(false);
 210                         }
 211                         // directed?
 212                         fin >> buf;
 213                         if(!strcmp(buf, "Y")) {
 214                                 ap->directed = true;
 215                         } else if(!strcmp(buf, "N")) {
 216                                 ap->directed = false;
 217                         } else {
 218                                 SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown arc directed value in taxi network - should be Y/N !!!\n");
 219                                 delete ap;
 220                                 return(false);
 221                         }
 222                         // Now the name
 223                         ap->name = "";
 224                         while(1) {
 225                                 fin.unsetf(ios::skipws);
 226                                 fin >> ch;
 227                                 ap->name += ch;
 228                                 if((ch == '"') || (ch == 0x0A)) {
 229                                         break;
 230                                 }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
 231                         }
 232                         fin.setf(ios::skipws);
 233                         ap->distance = (int)dclGetHorizontalSeparation(network[ap->n1]->pos, network[ap->n2]->pos);
 234                         //cout << "Distance  = " << ap->distance << '\n';
 235                         network[ap->n1]->arcs.push_back(ap);
 236                         network[ap->n2]->arcs.push_back(ap);
 237                 } else if(!strcmp(buf, "G")) {
 238                         gp = new Gate;
 239                         gp->struct_type = NODE;
 240                         gp->type = GATE;
 241                         fin >> buf;
 242                         gp->nodeID = atoi(buf);
 243                         fin >> buf;
 244                         gp->pos.setLongitudeDeg(atof(buf));
 245                         fin >> buf;
 246                         gp->pos.setLatitudeDeg(atof(buf));
 247                         fin >> buf;
 248                         gp->pos.setElevationM(atof(buf));
 249                         fin >> buf;             // gate type - ignore this for now
 250                         fin >> buf;             // gate heading
 251                         gp->heading = atoi(buf);
 252                         // Now the name
 253                         gp->name = "";
 254                         while(1) {
 255                                 fin.unsetf(ios::skipws);
 256                                 fin >> ch;
 257                                 gp->name += ch;
 258                                 if((ch == '"') || (ch == 0x0A)) {
 259                                         break;
 260                                 }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
 261                         }
 262                         fin.setf(ios::skipws);
 263                         gp->id = gateCount;             // Warning - this will likely change in the future.
 264                         gp->used = false;
 265                         network.push_back(gp);
 266                         gates[gateCount] = gp;
 267                         gateCount++;
 268                 } else {
 269                         // Something has gone seriously pear-shaped
 270                         SG_LOG(SG_ATC, SG_ALERT, "********* ERROR - unknown ground network element type... aborting read of " << path.c_str() << '\n');
 271                         return(false);
 272                 }
 273
 274                 fin >> skipeol;
 275         }
 276         return(true);
 277 }
 278
 279 void FGGround::Init() {
 280         untowered = false;
 281
 282         // Figure out which is the active runway - TODO - it would be better to have ground call tower
 283         // for runway operation details, but at the moment we can't guarantee that tower control at a given airport
 284         // will be initialised before ground so we can't do that.
 285         DoRwyDetails();
 286         //cout << "In FGGround::Init, active rwy is " << activeRwy << '\n';
 287         ortho.Init(rwy.threshold_pos, rwy.hdg);
 288
 289         networkLoadOK = LoadNetwork();
 290 }
 291
 292 void FGGround::Update(double dt) {
 293         // Each time step, what do we need to do?
 294         // We need to go through the list of outstanding requests and acknowedgements
 295         // and process at least one of them.
 296         // We need to go through the list of planes under our control and check if
 297         // any need to be addressed.
 298         // We need to check for planes not under our control coming within our
 299         // control area and address if necessary.
 300
 301         // Lets take the example of a plane which has just contacted ground
 302         // following landing - presumably requesting where to go?
 303         // First we need to establish the position of the plane within the logical network.
 304         // Next we need to decide where its going.
 305
 306         if(ground_traffic.size()) {
 307                 if(ground_traffic_itr == ground_traffic.end()) {
 308                         ground_traffic_itr = ground_traffic.begin();
 309                 }
 310
 311                 //Process(*ground_traffic_itr);
 312                 GroundRec* g = *ground_traffic_itr;
 313                 if(g->taxiRequestOutstanding) {
 314                         double responseTime = 10.0;             // seconds - this should get more sophisticated at some point
 315                         if(g->clearanceCounter > responseTime) {
 316                                 // DO CLEARANCE
 317                                 // TODO - move the mechanics of making up the transmission out of the main Update(...) routine.
 318                                 string trns = "";
 319                                 trns += g->plane.callsign;
 320                                 trns += " taxi holding point runway ";  // TODO - add the holding point name
 321                                 // eg " taxi holding point G2 runway "
 322                                 trns += ConvertRwyNumToSpokenString(activeRwy);
 323                                 if(_display) {
 324                                         fgSetString("/sim/messages/ground", trns.c_str());
 325                                 }
 326                                 g->planePtr->RegisterTransmission(1);   // cleared to taxi
 327                                 g->clearanceCounter = 0.0;
 328                                 g->taxiRequestOutstanding = false;
 329                         } else {
 330                                 g->clearanceCounter += (dt * ground_traffic.size());
 331                         }
 332                 } else if(((FGAILocalTraffic*)(g->planePtr))->AtHoldShort()) {          // That's a hack - eventually we should monitor actual position
 333                         // HACK ALERT - the automatic cast to AILocalTraffic has to go once we have other sorts working!!!!! FIXME TODO
 334                         // NOTE - we don't need to do the contact tower bit unless we have separate tower and ground
 335                         string trns = g->plane.callsign;
 336                         trns += " contact Tower ";
 337                         double f = globals->get_ATC_mgr()->GetFrequency(ident, TOWER) / 100.0;
 338                         char buf[10];
 339                         sprintf(buf, "%.2f", f);
 340                         trns += buf;
 341                         if(_display) {
 342                                 fgSetString("/sim/messages/ground", trns.c_str());
 343                         }
 344                         g->planePtr->RegisterTransmission(2);   // contact tower
 345                         delete *ground_traffic_itr;
 346                         ground_traffic.erase(ground_traffic_itr);
 347                         ground_traffic_itr = ground_traffic.begin();
 348                 }
 349                 ++ground_traffic_itr;
 350         }
 351
 352         // Call the base class update for the response time handling.
 353         FGATC::Update(dt);
 354 }
 355
 356 // Figure out which runways are active.
 357 // For now we'll just be simple and do one active runway - eventually this will get much more complex
 358 // Copied from FGTower - TODO - it would be better to implement this just once, and have ground call tower
 359 // for runway operation details, but at the moment we can't guarantee that tower control at a given airport
 360 // will be initialised before ground so we can't do that.
 361 void FGGround::DoRwyDetails() {
 362         //cout << "GetRwyDetails called" << endl;
 363
 364   const FGAirport* apt = fgFindAirportID(ident);
 365   assert(apt);
 366         FGRunway* runway = apt->getActiveRunwayForUsage();
 367
 368   activeRwy = runway->ident();
 369   rwy.rwyID = runway->ident();
 370   SG_LOG(SG_ATC, SG_INFO, "In FGGround, active runway for airport " << ident << " is " << activeRwy);
 371
 372   // Get the threshold position
 373   double other_way = runway->headingDeg() - 180.0;
 374   while(other_way <= 0.0) {
 375     other_way += 360.0;
 376   }
 377     // move to the +l end/center of the runway
 378   //cout << "Runway center is at " << runway._lon << ", " << runway._lat << '\n';
 379   double tshlon = 0.0, tshlat = 0.0, tshr = 0.0;
 380   double tolon = 0.0, tolat = 0.0, tor = 0.0;
 381   rwy.length = runway->lengthM();
 382   geo_direct_wgs_84 ( aptElev, runway->latitude(), runway->longitude(), other_way,
 383                       rwy.length / 2.0 - 25.0, &tshlat, &tshlon, &tshr );
 384   geo_direct_wgs_84 ( aptElev, runway->latitude(), runway->longitude(), runway->headingDeg(),
 385                       rwy.length / 2.0 - 25.0, &tolat, &tolon, &tor );
 386   // Note - 25 meters in from the runway end is a bit of a hack to put the plane ahead of the user.
 387   // now copy what we need out of runway into rwy
 388   rwy.threshold_pos = SGGeod::fromDegM(tshlon, tshlat, aptElev);
 389   SGGeod takeoff_end = SGGeod::fromDegM(tolon, tolat, aptElev);
 390   //cout << "Threshold position = " << tshlon << ", " << tshlat << ", " << aptElev << '\n';
 391   //cout << "Takeoff position = " << tolon << ", " << tolat << ", " << aptElev << '\n';
 392   rwy.hdg = runway->headingDeg();
 393   // Set the projection for the local area based on this active runway
 394   ortho.Init(rwy.threshold_pos, rwy.hdg);
 395   rwy.end1ortho = ortho.ConvertToLocal(rwy.threshold_pos);      // should come out as zero
 396   rwy.end2ortho = ortho.ConvertToLocal(takeoff_end);
 397 }
 398
 399 // Return a random gate ID of an unused gate.
 400 // Two error values may be returned and must be checked for by the calling function:
 401 // -2 signifies that no gates exist at this airport.
 402 // -1 signifies that all gates are currently full.
 403 int FGGround::GetRandomGateID() {
 404         // Check that this airport actually has some gates!!
 405         if(!gates.size()) {
 406                 return(-2);
 407         }
 408
 409         gate_vec_type gateVec;
 410         int num = 0;
 411         int thenum;
 412         int ID;
 413
 414         gatesItr = gates.begin();
 415         while(gatesItr != gates.end()) {
 416                 if((gatesItr->second)->used == false) {
 417                         gateVec.push_back(gatesItr->second);
 418                         num++;
 419                 }
 420                 ++gatesItr;
 421         }
 422
 423         // Check that there are some unused gates!
 424         if(!gateVec.size()) {
 425                 return(-1);
 426         }
 427
 428         // Randomly select one from the list
 429         sg_srandom_time();
 430         thenum = (int)(sg_random() * gateVec.size());
 431         ID = gateVec[thenum]->id;
 432
 433         return(ID);
 434 }
 435
 436 // Return a pointer to an unused gate node
 437 Gate* FGGround::GetGateNode() {
 438         int id = GetRandomGateID();
 439         if(id < 0) {
 440                 return(NULL);
 441         } else {
 442                 return(gates[id]);
 443         }
 444 }
 445
 446
 447 node* FGGround::GetHoldShortNode(const string& rwyID) {
 448         return(NULL);   // TODO - either implement me or remove me!!!
 449 }
 450
 451
 452 // WARNING - This is hardwired to my prototype logical network format
 453 // and will almost certainly change when Bernie's stuff comes on-line.
 454 // Returns NULL if it can't find a valid node.
 455 node* FGGround::GetThresholdNode(const string& rwyID) {
 456         // For now go through all the nodes and parse their names
 457         // Maybe in the future we'll map threshold nodes by ID
 458         //cout << "Size of network is " << network.size() << '\n';
 459         for(unsigned int i=0; i<network.size(); ++i) {
 460                 //cout << "Name = " << network[i]->name << '\n';
 461                 if(network[i]->name.size()) {
 462                         string s = network[i]->name;
 463                         // Warning - the next bit is fragile and dependent on my current naming scheme
 464                         //cout << "substr = " << s.substr(0,3) << '\n';
 465                         //cout << "size of s = " << s.size() << '\n';
 466                         if(s.substr(0,3) == "rwy") {
 467                                 //cout << "subsubstr = " << s.substr(4, s.size() - 4) << '\n';
 468                                 if(s.substr(4, s.size() - 4) == rwyID) {
 469                                         return network[i];
 470                                 }
 471                         }
 472                 }
 473         }
 474         return NULL;
 475 }
 476
 477
 478 // Get a path from a point on a runway to a gate
 479 // TODO !!
 480
 481 // Get a path from a node to another node
 482 // Eventually we will need complex algorithms for this taking other traffic,
 483 // shortest path and suitable paths into accout.
 484 // For now we'll just call the shortest path algorithm.
 485 ground_network_path_type FGGround::GetPath(node* A, node* B) {
 486         return(GetShortestPath(A, B));
 487 };
 488
 489 // Get a path from a node to a runway threshold
 490 ground_network_path_type FGGround::GetPath(node* A, const string& rwyID) {
 491         node* b = GetThresholdNode(rwyID);
 492         if(b == NULL) {
 493                 SG_LOG(SG_ATC, SG_ALERT, "ERROR - unable to find path to runway theshold in ground.cxx for airport " << ident << '\n');
 494                 ground_network_path_type emptyPath;
 495                 emptyPath.erase(emptyPath.begin(), emptyPath.end());
 496                 return(emptyPath);
 497         }
 498         return GetShortestPath(A, b);
 499 }
 500
 501 // Get a path from a node to a runway hold short point
 502 // Bit of a hack this at the moment!
 503 ground_network_path_type FGGround::GetPathToHoldShort(node* A, const string& rwyID) {
 504         ground_network_path_type path = GetPath(A, rwyID);
 505         path.pop_back();        // That should be the threshold stripped of
 506         path.pop_back();        // and that should be the arc from hold short to threshold
 507         // This isn't robust though - TODO - implement properly!
 508         return(path);
 509 }
 510
 511 // A shortest path algorithm from memory (ie. I can't find the bl&*dy book again!)
 512 // I'm sure there must be enchancements that we can make to this, such as biasing the
 513 // order in which the nodes are searched out from in favour of those geographically
 514 // closer to the destination.
 515 // Note that we are working with the master set of nodes and arcs so we mustn't change
 516 // or delete them -  we only delete the paths that we create during the algorithm.
 517 ground_network_path_type FGGround::GetShortestPath(node* A, node* B) {
 518         a_path* pathPtr;
 519         shortest_path_map_type pathMap;
 520         node_array_type nodesLeft;
 521
 522         // Debugging check
 523         int pathsCreated = 0;
 524
 525         // Initialise the algorithm
 526         nodesLeft.push_back(A);
 527         pathPtr = new a_path;
 528         pathsCreated++;
 529         pathPtr->path.push_back(A);
 530         pathPtr->cost = 0;
 531         pathMap[A->nodeID] = pathPtr;
 532         bool solution_found = false;    // Flag to indicate that at least one candidate path has been found
 533         int solution_cost = -1;                 // Cost of current best cost solution.  -1 indicates no solution found yet.
 534         a_path solution_path;
 535
 536         node* nPtr;     // nPtr is used to point to the node we are currently working with
 537
 538         while(nodesLeft.size()) {
 539                 //cout << "\n*****nodesLeft*****\n";
 540                 //for(unsigned int i=0; i<nodesLeft.size(); ++i) {
 541                         //cout << nodesLeft[i]->nodeID << '\n';
 542                 //}
 543                 //cout << "*******************\n\n";
 544                 nPtr = *nodesLeft.begin();              // Thought - definate optimization possibilities here in the choice of which nodes we process first.
 545                 nodesLeft.erase(nodesLeft.begin());
 546                 //cout << "Walking out from node " << nPtr->nodeID << '\n';
 547                 for(unsigned int i=0; i<nPtr->arcs.size(); ++i) {
 548                         //cout << "ARC TO " << ((nPtr->arcs[i]->n1 == nPtr->nodeID) ? nPtr->arcs[i]->n2 : nPtr->arcs[i]->n1) << '\n';
 549                 }
 550                 if((solution_found) && (solution_cost <= pathMap[nPtr->nodeID]->cost)) {
 551                         // Do nothing - we've already found a solution and this partial path is already more expensive
 552                 } else {
 553                         // This path could still be better than the current solution - check it out
 554                         for(unsigned int i=0; i<(nPtr->arcs.size()); i++) {
 555                                 // Map the new path against the end node, ie. *not* the one we just started with.
 556                                 unsigned int end_nodeID = ((nPtr->arcs[i]->n1 == nPtr->nodeID) ? nPtr->arcs[i]->n2 : nPtr->arcs[i]->n1);
 557                                 //cout << "end_nodeID = " << end_nodeID << '\n';
 558                                 //cout << "pathMap size is " << pathMap.size() << '\n';
 559                                 if(end_nodeID == nPtr->nodeID) {
 560                                         //cout << "Circular arc!\n";
 561                                         // Then its a circular arc - don't bother!!
 562                                         //nPtr->arcs.erase(nPtr->arcs.begin() + i);
 563                                 } else {
 564                                         // see if the end node is already in the map or not
 565                                         if(pathMap.find(end_nodeID) == pathMap.end()) {
 566                                                 //cout << "Not in the map" << endl;;
 567                                                 // Not in the map - easy!
 568                                                 pathPtr = new a_path;
 569                                                 pathsCreated++;
 570                                                 *pathPtr = *pathMap[nPtr->nodeID];      // *copy* the path
 571                                                 pathPtr->path.push_back(nPtr->arcs[i]);
 572                                                 pathPtr->path.push_back(network[end_nodeID]);
 573                                                 pathPtr->cost += nPtr->arcs[i]->distance;
 574                                                 pathMap[end_nodeID] = pathPtr;
 575                                                 nodesLeft.push_back(network[end_nodeID]);       // By definition this can't be in the list already, or
 576                                                 // it would also have been in the map and hence OR'd with this one.
 577                                                 if(end_nodeID == B->nodeID) {
 578                                                         //cout << "Solution found!!!" << endl;
 579                                                         // Since this node wasn't in the map this is by definition the first solution
 580                                                         solution_cost = pathPtr->cost;
 581                                                         solution_path = *pathPtr;
 582                                                         solution_found = true;
 583                                                 }
 584                                         } else {
 585                                                 //cout << "Already in the map" << endl;
 586                                                 // In the map - not so easy - need to get rid of an arc from the higher cost one.
 587                                                 //cout << "Current cost of node " << end_nodeID << " is " << pathMap[end_nodeID]->cost << endl;
 588                                                 int newCost = pathMap[nPtr->nodeID]->cost + nPtr->arcs[i]->distance;
 589                                                 //cout << "New cost is of node " << nPtr->nodeID << " is " << newCost << endl;
 590                                                 if(newCost >= pathMap[end_nodeID]->cost) {
 591                                                         // No need to do anything.
 592                                                         //cout << "Not doing anything!" << endl;
 593                                                 } else {
 594                                                         delete pathMap[end_nodeID];
 595                                                         pathsCreated--;
 596
 597                                                         pathPtr = new a_path;
 598                                                         pathsCreated++;
 599                                                         *pathPtr = *pathMap[nPtr->nodeID];      // *copy* the path
 600                                                         pathPtr->path.push_back(nPtr->arcs[i]);
 601                                                         pathPtr->path.push_back(network[end_nodeID]);
 602                                                         pathPtr->cost += nPtr->arcs[i]->distance;
 603                                                         pathMap[end_nodeID] = pathPtr;
 604
 605                                                         // We need to add this node to the list-to-do again to force a recalculation
 606                                                         // onwards from this node with the new lower cost to node cost.
 607                                                         nodesLeft.push_back(network[end_nodeID]);
 608
 609                                                         if(end_nodeID == B->nodeID) {
 610                                                                 //cout << "Solution found!!!" << endl;
 611                                                                 // Need to check if there is a previous better solution
 612                                                                 if((solution_cost < 0) || (pathPtr->cost < solution_cost)) {
 613                                                                         solution_cost = pathPtr->cost;
 614                                                                         solution_path = *pathPtr;
 615                                                                         solution_found = true;
 616                                                                 }
 617                                                         }
 618                                                 }
 619                                         }
 620                                 }
 621                         }
 622                 }
 623         }
 624
 625         // delete all the paths before returning
 626         shortest_path_map_iterator spItr = pathMap.begin();
 627         while(spItr != pathMap.end()) {
 628                 if(spItr->second != NULL) {
 629                         delete spItr->second;
 630                         --pathsCreated;
 631                 }
 632                 ++spItr;
 633         }
 634
 635         //cout << "pathsCreated = " << pathsCreated << '\n';
 636         if(pathsCreated > 0) {
 637                 SG_LOG(SG_ATC, SG_ALERT, "WARNING - Possible memory leak in FGGround::GetShortestPath\n\
 638                                                                           Please report to flightgear-devel@flightgear.org\n");
 639         }
 640
 641         //cout << (solution_found ? "Result: solution found\n" : "Result: no solution found\n");
 642         return(solution_path.path);             // TODO - we really ought to have a fallback position incase a solution isn't found.
 643 }
 644
 645
 646
 647 // Randomly or otherwise populate some of the gates with parked planes
 648 // (might eventually be done by the AIMgr if and when lots of AI traffic is generated)
 649
 650 // Return a list of exits from a given runway
 651 // It is up to the calling function to check for non-zero size of returned array before use
 652 node_array_type FGGround::GetExits(const string& rwyID) {
 653         // FIXME - get a 07L or similar in here and we're stuffed!!!
 654         return(runways[atoi(rwyID.c_str())].exits);
 655 }
 656
 657 void FGGround::RequestDeparture(const PlaneRec& plane, FGAIEntity* requestee) {
 658         // For now we'll just automatically clear all planes to the runway hold.
 659         // This communication needs to be delayed 20 sec or so from receiving the request.
 660         // Even if display=false we still need to start the timer in case display=true when communication starts.
 661         // We also need to bear in mind we also might have other outstanding communications, although for now we'll punt that issue!
 662         // FIXME - sort the above!
 663
 664         // HACK - assume that anything requesting departure is new for now - FIXME LATER
 665         GroundRec* g = new GroundRec;
 666         g->plane = plane;
 667         g->planePtr = requestee;
 668         g->taxiRequestOutstanding = true;
 669         g->clearanceCounter = 0;
 670         g->cleared = false;
 671         g->incoming = false;
 672         // TODO - need to handle the next 3 as well
 673     //node* destination;
 674     //node* last_clearance;
 675
 676         ground_traffic.push_back(g);
 677 }
 678
 679 #if 0
 680 void FGGround::NewArrival(plane_rec plane) {
 681         // What are we going to do here?
 682         // We need to start a new ground_rec and add the plane_rec to it
 683         // We need to decide what gate we are going to clear it to.
 684         // Then we need to add clearing it to that gate to the pending transmissions queue? - or simply transmit?
 685         // Probably simply transmit for now and think about a transmission queue later if we need one.
 686         // We might need one though in order to add a little delay for response time.
 687         ground_rec* g = new ground_rec;
 688         g->plane_rec = plane;
 689         g->current_pos = ConvertWGS84ToXY(plane.pos);
 690         g->node = GetNode(g->current_pos);  // TODO - might need to sort out node/arc here
 691         AssignGate(g);
 692         g->cleared = false;
 693         ground_traffic.push_back(g);
 694         NextClearance(g);
 695 }
 696
 697 void FGGround::NewContact(plane_rec plane) {
 698         // This is a bit of a convienience function at the moment and is likely to change.
 699         if(at a gate or apron)
 700                 NewDeparture(plane);
 701         else
 702                 NewArrival(plane);
 703 }
 704
 705 void FGGround::NextClearance(ground_rec &g) {
 706         // Need to work out where we can clear g to.
 707         // Assume the pilot doesn't need progressive instructions
 708         // We *should* already have a gate or holding point assigned by the time we get here
 709         // but it wouldn't do any harm to check.
 710
 711         // For now though we will hardwire it to clear to the final destination.
 712 }
 713
 714 void FGGround::AssignGate(ground_rec &g) {
 715         // We'll cheat for now - since we only have the user's aircraft and a couple of airports implemented
 716         // we'll hardwire the gate!
 717         // In the long run the logic of which gate or area to send the plane to could be somewhat non-trivial.
 718 }
 719 #endif //0
 720