src/ATC/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., 675 Mass Ave, Cambridge, MA 02139, USA.
  20
  21 #ifdef HAVE_CONFIG_H
  22 #  include <config.h>
  23 #endif
  24
  25 #include <simgear/misc/sg_path.hxx>
  26 #include <simgear/math/sg_random.h>
  27 #include <simgear/debug/logstream.hxx>
  28 #include <simgear/misc/sgstream.hxx>
  29 #include <simgear/constants.h>
  30 #include <Main/globals.hxx>
  31
  32 #include <stdlib.h>
  33 #include STL_FSTREAM
  34
  35 #include "ground.hxx"
  36 #include "ATCmgr.hxx"
  37 #include "ATCutils.hxx"
  38 #include "ATCdisplay.hxx"
  39 #include "AILocalTraffic.hxx"
  40
  41 SG_USING_STD(ifstream);
  42 SG_USING_STD(cout);
  43
  44 node::node() {
  45 }
  46
  47 node::~node() {
  48         for(unsigned int i=0; i < arcs.size(); ++i) {
  49                 delete arcs[i];
  50         }
  51 }
  52
  53 // Make sure that a_path.cost += distance is safe from the moment it's created.
  54 a_path::a_path() {
  55         cost = 0;
  56 }
  57
  58 FGGround::FGGround() {
  59         ATCmgr = globals->get_ATC_mgr();
  60         _type = GROUND;
  61         networkLoadOK = false;
  62         ground_traffic.erase(ground_traffic.begin(), ground_traffic.end());
  63         ground_traffic_itr = ground_traffic.begin();
  64
  65         // Init the property nodes - TODO - need to make sure we're getting surface winds.
  66         wind_from_hdg = fgGetNode("/environment/wind-from-heading-deg", true);
  67         wind_speed_knots = fgGetNode("/environment/wind-speed-kt", true);
  68
  69         // TODO - get the actual airport elevation
  70         aptElev = 0.0;
  71 }
  72
  73 FGGround::FGGround(const string& id) {
  74         ATCmgr = globals->get_ATC_mgr();
  75         networkLoadOK = false;
  76         ground_traffic.erase(ground_traffic.begin(), ground_traffic.end());
  77         ground_traffic_itr = ground_traffic.begin();
  78         ident = id;
  79
  80         // Init the property nodes - TODO - need to make sure we're getting surface winds.
  81         wind_from_hdg = fgGetNode("/environment/wind-from-heading-deg", true);
  82         wind_speed_knots = fgGetNode("/environment/wind-speed-kt", true);
  83
  84         // TODO - get the actual airport elevation
  85         aptElev = 0.0;
  86 }
  87
  88 FGGround::~FGGround() {
  89 }
  90
  91 void FGGround::ParseRwyExits(node* np, char* es) {
  92         char* token;
  93         char estr[20];
  94         strcpy(estr, es);
  95         const char delimiters[] = "-";
  96         token = strtok(estr, delimiters);
  97         while(token != NULL) {
  98                 int i = atoi(token);
  99                 //cout << "token = " << token << endl;
 100                 //cout << "rwy number = " << i << endl;
 101                 //runways[(atoi(token))].exits.push_back(np);
 102                 runways[i].exits.push_back(np);
 103                 //cout << "token = " << token << '\n';
 104                 token = strtok(NULL, delimiters);
 105         }
 106 }
 107
 108
 109 // Load the ground logical network of the current instances airport
 110 // Return true if successfull.
 111 // TODO - currently the file is assumed to reside in the base/ATC directory.
 112 // This might change to something more thought out in the future.
 113 // NOTE - currently it is assumed that all nodes are loaded before any arcs.
 114 // It won't work ATM if this doesn't hold true.
 115 bool FGGround::LoadNetwork() {
 116         node* np;
 117         arc* ap;
 118         Gate* gp;
 119
 120         int gateCount = 0;      // This is used to allocate gateID's from zero upwards
 121         // This may well change in the future - probably to reading in the real-world
 122         // gate numbers from file.
 123
 124         ifstream fin;
 125         SGPath path = globals->get_fg_root();
 126         //string taxiPath = "ATC/" + ident + ".taxi";
 127         string taxiPath = "ATC/KEMT.taxi";      // FIXME - HARDWIRED FOR TESTING
 128         path.append(taxiPath);
 129
 130         SG_LOG(SG_ATC, SG_INFO, "Trying to read taxiway data for " << ident << "...");
 131         //cout << "Trying to read taxiway data for " << ident << "..." << endl;
 132         fin.open(path.c_str(), ios::in);
 133         if(!fin) {
 134                 SG_LOG(SG_ATC, SG_ALERT, "Unable to open taxiway data input file " << path.c_str());
 135                 //cout << "Unable to open taxiway data input file " << path.c_str() << endl;
 136                 return(false);
 137         }
 138
 139         char ch;
 140         char buf[30];
 141         while(!fin.eof()) {
 142                 fin >> buf;
 143                 // Node, arc, or [End]?
 144                 //cout << "Read in ground network element type = " << buf << endl;
 145                 if(!strcmp(buf, "[End]")) {             // TODO - maybe make this more robust to spelling errors by just looking for '['
 146                         SG_LOG(SG_ATC, SG_INFO, "Done reading " << path.c_str() << endl);
 147                         break;
 148                 } else if(!strcmp(buf, "N")) {
 149                         // Node
 150                         np = new node;
 151                         np->struct_type = NODE;
 152                         fin >> buf;
 153                         np->nodeID = atoi(buf);
 154                         fin >> buf;
 155                         np->pos.setlon(atof(buf));
 156                         fin >> buf;
 157                         np->pos.setlat(atof(buf));
 158                         fin >> buf;
 159                         np->pos.setelev(atof(buf));
 160                         fin >> buf;             // node type
 161                         if(!strcmp(buf, "J")) {
 162                                 np->type = JUNCTION;
 163                         } else if(!strcmp(buf, "T")) {
 164                                 np->type = TJUNCTION;
 165                         } else if(!strcmp(buf, "H")) {
 166                                 np->type = HOLD;
 167                         } else {
 168                                 SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown node type in taxi network...\n");
 169                                 delete np;
 170                                 return(false);
 171                         }
 172                         fin >> buf;             // rwy exit information - gets parsed later - FRAGILE - will break if buf is reused.
 173                         // Now the name
 174                         fin >> ch;      // strip the leading " off
 175                         np->name = "";
 176                         while(1) {
 177                                 fin.unsetf(ios::skipws);
 178                                 fin >> ch;
 179                                 if((ch == '"') || (ch == 0x0A)) {
 180                                         break;
 181                                 }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
 182                                 np->name += ch;
 183                         }
 184                         fin.setf(ios::skipws);
 185                         network.push_back(np);
 186                         // FIXME - fragile - replies on buf not getting modified from exits read to here
 187                         // see if we also need to push it onto the runway exit list
 188                         //cout << "strlen(buf) = " << strlen(buf) << endl;
 189                         if(strlen(buf) > 2) {
 190                                 //cout << "Calling ParseRwyExits for " << buf << endl;
 191                                 ParseRwyExits(np, buf);
 192                         }
 193                 } else if(!strcmp(buf, "A")) {
 194                         ap = new arc;
 195                         ap->struct_type = ARC;
 196                         fin >> buf;
 197                         ap->n1 = atoi(buf);
 198                         fin >> buf;
 199                         ap->n2 = atoi(buf);
 200                         fin >> buf;
 201                         if(!strcmp(buf, "R")) {
 202                                 ap->type = RUNWAY;
 203                         } else if(!strcmp(buf, "T")) {
 204                                 ap->type = TAXIWAY;
 205                         } else {
 206                                 SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown arc type in taxi network...\n");
 207                                 delete ap;
 208                                 return(false);
 209                         }
 210                         // directed?
 211                         fin >> buf;
 212                         if(!strcmp(buf, "Y")) {
 213                                 ap->directed = true;
 214                         } else if(!strcmp(buf, "N")) {
 215                                 ap->directed = false;
 216                         } else {
 217                                 SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown arc directed value in taxi network - should be Y/N !!!\n");
 218                                 delete ap;
 219                                 return(false);
 220                         }
 221                         // Now the name
 222                         ap->name = "";
 223                         while(1) {
 224                                 fin.unsetf(ios::skipws);
 225                                 fin >> ch;
 226                                 ap->name += ch;
 227                                 if((ch == '"') || (ch == 0x0A)) {
 228                                         break;
 229                                 }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
 230                         }
 231                         fin.setf(ios::skipws);
 232                         ap->distance = (int)dclGetHorizontalSeparation(network[ap->n1]->pos, network[ap->n2]->pos);
 233                         //cout << "Distance  = " << ap->distance << '\n';
 234                         network[ap->n1]->arcs.push_back(ap);
 235                         network[ap->n2]->arcs.push_back(ap);
 236                 } else if(!strcmp(buf, "G")) {
 237                         gp = new Gate;
 238                         gp->struct_type = NODE;
 239                         gp->type = GATE;
 240                         fin >> buf;
 241                         gp->nodeID = atoi(buf);
 242                         fin >> buf;
 243                         gp->pos.setlon(atof(buf));
 244                         fin >> buf;
 245                         gp->pos.setlat(atof(buf));
 246                         fin >> buf;
 247                         gp->pos.setelev(atof(buf));
 248                         fin >> buf;             // gate type - ignore this for now
 249                         fin >> buf;             // gate heading
 250                         gp->heading = atoi(buf);
 251                         // Now the name
 252                         gp->name = "";
 253                         while(1) {
 254                                 fin.unsetf(ios::skipws);
 255                                 fin >> ch;
 256                                 gp->name += ch;
 257                                 if((ch == '"') || (ch == 0x0A)) {
 258                                         break;
 259                                 }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
 260                         }
 261                         fin.setf(ios::skipws);
 262                         gp->id = gateCount;             // Warning - this will likely change in the future.
 263                         gp->used = false;
 264                         network.push_back(gp);
 265                         gates[gateCount] = gp;
 266                         gateCount++;
 267                 } else {
 268                         // Something has gone seriously pear-shaped
 269                         SG_LOG(SG_ATC, SG_ALERT, "********* ERROR - unknown ground network element type... aborting read of " << path.c_str() << '\n');
 270                         return(false);
 271                 }
 272
 273                 fin >> skipeol;
 274         }
 275         return(true);
 276 }
 277
 278 void FGGround::Init() {
 279         untowered = false;
 280
 281         // Figure out which is the active runway - TODO - it would be better to have ground call tower
 282         // for runway operation details, but at the moment we can't guarantee that tower control at a given airport
 283         // will be initialised before ground so we can't do that.
 284         DoRwyDetails();
 285         //cout << "In FGGround::Init, active rwy is " << activeRwy << '\n';
 286         ortho.Init(rwy.threshold_pos, rwy.hdg);
 287
 288         networkLoadOK = LoadNetwork();
 289 }
 290
 291 void FGGround::Update(double dt) {
 292         // Each time step, what do we need to do?
 293         // We need to go through the list of outstanding requests and acknowedgements
 294         // and process at least one of them.
 295         // We need to go through the list of planes under our control and check if
 296         // any need to be addressed.
 297         // We need to check for planes not under our control coming within our
 298         // control area and address if necessary.
 299
 300         // Lets take the example of a plane which has just contacted ground
 301         // following landing - presumably requesting where to go?
 302         // First we need to establish the position of the plane within the logical network.
 303         // Next we need to decide where its going.
 304
 305         if(ground_traffic.size()) {
 306                 if(ground_traffic_itr == ground_traffic.end()) {
 307                         ground_traffic_itr = ground_traffic.begin();
 308                 }
 309
 310                 //Process(*ground_traffic_itr);
 311                 GroundRec* g = *ground_traffic_itr;
 312                 if(g->taxiRequestOutstanding) {
 313                         double responseTime = 10.0;             // seconds - this should get more sophisticated at some point
 314                         if(g->clearanceCounter > responseTime) {
 315                                 // DO CLEARANCE
 316                                 // TODO - move the mechanics of making up the transmission out of the main Update(...) routine.
 317                                 string trns = "";
 318                                 trns += g->plane.callsign;
 319                                 trns += " taxi holding point runway ";  // TODO - add the holding point name
 320                                 // eg " taxi holding point G2 runway "
 321                                 trns += ConvertRwyNumToSpokenString(activeRwy);
 322                                 if(_display) {
 323                                         fgSetString("/sim/messages/ground", trns.c_str());
 324                                         globals->get_ATC_display()->RegisterSingleMessage(trns, 0);
 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                                 globals->get_ATC_display()->RegisterSingleMessage(trns, 0);
 344                         }
 345                         g->planePtr->RegisterTransmission(2);   // contact tower
 346                         delete *ground_traffic_itr;
 347                         ground_traffic.erase(ground_traffic_itr);
 348                         ground_traffic_itr = ground_traffic.begin();
 349                 }
 350                 ++ground_traffic_itr;
 351         }
 352
 353         // Call the base class update for the response time handling.
 354         FGATC::Update(dt);
 355 }
 356
 357 // Figure out which runways are active.
 358 // For now we'll just be simple and do one active runway - eventually this will get much more complex
 359 // Copied from FGTower - TODO - it would be better to implement this just once, and have ground call tower
 360 // for runway operation details, but at the moment we can't guarantee that tower control at a given airport
 361 // will be initialised before ground so we can't do that.
 362 void FGGround::DoRwyDetails() {
 363         //cout << "GetRwyDetails called" << endl;
 364
 365         // Based on the airport-id and wind get the active runway
 366
 367         //wind
 368         double hdg = wind_from_hdg->getDoubleValue();
 369         double speed = wind_speed_knots->getDoubleValue();
 370         hdg = (speed == 0.0 ? 270.0 : hdg);
 371         //cout << "Heading = " << hdg << '\n';
 372
 373         FGRunway runway;
 374         bool rwyGood = globals->get_runways()->search(ident, int(hdg), &runway);
 375         if(rwyGood) {
 376                 activeRwy = runway._rwy_no;
 377                 rwy.rwyID = runway._rwy_no;
 378                 SG_LOG(SG_ATC, SG_INFO, "In FGGround, active runway for airport " << ident << " is " << activeRwy);
 379
 380                 // Get the threshold position
 381                 double other_way = runway._heading - 180.0;
 382                 while(other_way <= 0.0) {
 383                         other_way += 360.0;
 384                 }
 385         // move to the +l end/center of the runway
 386                 //cout << "Runway center is at " << runway._lon << ", " << runway._lat << '\n';
 387         Point3D origin = Point3D(runway._lon, runway._lat, aptElev);
 388                 Point3D ref = origin;
 389         double tshlon, tshlat, tshr;
 390                 double tolon, tolat, tor;
 391                 rwy.length = runway._length * SG_FEET_TO_METER;
 392         geo_direct_wgs_84 ( aptElev, ref.lat(), ref.lon(), other_way,
 393                                 rwy.length / 2.0 - 25.0, &tshlat, &tshlon, &tshr );
 394         geo_direct_wgs_84 ( aptElev, ref.lat(), ref.lon(), runway._heading,
 395                                 rwy.length / 2.0 - 25.0, &tolat, &tolon, &tor );
 396                 // Note - 25 meters in from the runway end is a bit of a hack to put the plane ahead of the user.
 397                 // now copy what we need out of runway into rwy
 398         rwy.threshold_pos = Point3D(tshlon, tshlat, aptElev);
 399                 Point3D takeoff_end = Point3D(tolon, tolat, aptElev);
 400                 //cout << "Threshold position = " << tshlon << ", " << tshlat << ", " << aptElev << '\n';
 401                 //cout << "Takeoff position = " << tolon << ", " << tolat << ", " << aptElev << '\n';
 402                 rwy.hdg = runway._heading;
 403                 // Set the projection for the local area based on this active runway
 404                 ortho.Init(rwy.threshold_pos, rwy.hdg);
 405                 rwy.end1ortho = ortho.ConvertToLocal(rwy.threshold_pos);        // should come out as zero
 406                 rwy.end2ortho = ortho.ConvertToLocal(takeoff_end);
 407         } else {
 408                 SG_LOG(SG_ATC, SG_ALERT, "Help  - can't get good runway in FGTower!!");
 409                 activeRwy = "NN";
 410         }
 411 }
 412
 413 // Return a random gate ID of an unused gate.
 414 // Two error values may be returned and must be checked for by the calling function:
 415 // -2 signifies that no gates exist at this airport.
 416 // -1 signifies that all gates are currently full.
 417 int FGGround::GetRandomGateID() {
 418         // Check that this airport actually has some gates!!
 419         if(!gates.size()) {
 420                 return(-2);
 421         }
 422
 423         gate_vec_type gateVec;
 424         int num = 0;
 425         int thenum;
 426         int ID;
 427
 428         gatesItr = gates.begin();
 429         while(gatesItr != gates.end()) {
 430                 if((gatesItr->second)->used == false) {
 431                         gateVec.push_back(gatesItr->second);
 432                         num++;
 433                 }
 434                 ++gatesItr;
 435         }
 436
 437         // Check that there are some unused gates!
 438         if(!gateVec.size()) {
 439                 return(-1);
 440         }
 441
 442         // Randomly select one from the list
 443         sg_srandom_time();
 444         thenum = (int)(sg_random() * gateVec.size());
 445         ID = gateVec[thenum]->id;
 446
 447         return(ID);
 448 }
 449
 450 // Return a pointer to an unused gate node
 451 Gate* FGGround::GetGateNode() {
 452         int id = GetRandomGateID();
 453         if(id < 0) {
 454                 return(NULL);
 455         } else {
 456                 return(gates[id]);
 457         }
 458 }
 459
 460
 461 node* FGGround::GetHoldShortNode(const string& rwyID) {
 462         return(NULL);   // TODO - either implement me or remove me!!!
 463 }
 464
 465
 466 // WARNING - This is hardwired to my prototype logical network format
 467 // and will almost certainly change when Bernie's stuff comes on-line.
 468 // Returns NULL if it can't find a valid node.
 469 node* FGGround::GetThresholdNode(const string& rwyID) {
 470         // For now go through all the nodes and parse their names
 471         // Maybe in the future we'll map threshold nodes by ID
 472         //cout << "Size of network is " << network.size() << '\n';
 473         for(unsigned int i=0; i<network.size(); ++i) {
 474                 //cout << "Name = " << network[i]->name << '\n';
 475                 if(network[i]->name.size()) {
 476                         string s = network[i]->name;
 477                         // Warning - the next bit is fragile and dependent on my current naming scheme
 478                         //cout << "substr = " << s.substr(0,3) << '\n';
 479                         //cout << "size of s = " << s.size() << '\n';
 480                         if(s.substr(0,3) == "rwy") {
 481                                 //cout << "subsubstr = " << s.substr(4, s.size() - 4) << '\n';
 482                                 if(s.substr(4, s.size() - 4) == rwyID) {
 483                                         return network[i];
 484                                 }
 485                         }
 486                 }
 487         }
 488         return NULL;
 489 }
 490
 491
 492 // Get a path from a point on a runway to a gate
 493 // TODO !!
 494
 495 // Get a path from a node to another node
 496 // Eventually we will need complex algorithms for this taking other traffic,
 497 // shortest path and suitable paths into accout.
 498 // For now we'll just call the shortest path algorithm.
 499 ground_network_path_type FGGround::GetPath(node* A, node* B) {
 500         return(GetShortestPath(A, B));
 501 };
 502
 503 // Get a path from a node to a runway threshold
 504 ground_network_path_type FGGround::GetPath(node* A, const string& rwyID) {
 505         node* b = GetThresholdNode(rwyID);
 506         if(b == NULL) {
 507                 SG_LOG(SG_ATC, SG_ALERT, "ERROR - unable to find path to runway theshold in ground.cxx for airport " << ident << '\n');
 508                 ground_network_path_type emptyPath;
 509                 emptyPath.erase(emptyPath.begin(), emptyPath.end());
 510                 return(emptyPath);
 511         }
 512         return GetShortestPath(A, b);
 513 }
 514
 515 // Get a path from a node to a runway hold short point
 516 // Bit of a hack this at the moment!
 517 ground_network_path_type FGGround::GetPathToHoldShort(node* A, const string& rwyID) {
 518         ground_network_path_type path = GetPath(A, rwyID);
 519         path.pop_back();        // That should be the threshold stripped of
 520         path.pop_back();        // and that should be the arc from hold short to threshold
 521         // This isn't robust though - TODO - implement properly!
 522         return(path);
 523 }
 524
 525 // A shortest path algorithm from memory (ie. I can't find the bl&*dy book again!)
 526 // I'm sure there must be enchancements that we can make to this, such as biasing the
 527 // order in which the nodes are searched out from in favour of those geographically
 528 // closer to the destination.
 529 // Note that we are working with the master set of nodes and arcs so we mustn't change
 530 // or delete them -  we only delete the paths that we create during the algorithm.
 531 ground_network_path_type FGGround::GetShortestPath(node* A, node* B) {
 532         a_path* pathPtr;
 533         shortest_path_map_type pathMap;
 534         node_array_type nodesLeft;
 535
 536         // Debugging check
 537         int pathsCreated = 0;
 538
 539         // Initialise the algorithm
 540         nodesLeft.push_back(A);
 541         pathPtr = new a_path;
 542         pathsCreated++;
 543         pathPtr->path.push_back(A);
 544         pathPtr->cost = 0;
 545         pathMap[A->nodeID] = pathPtr;
 546         bool solution_found = false;    // Flag to indicate that at least one candidate path has been found
 547         int solution_cost = -1;                 // Cost of current best cost solution.  -1 indicates no solution found yet.
 548         a_path solution_path;
 549
 550         node* nPtr;     // nPtr is used to point to the node we are currently working with
 551
 552         while(nodesLeft.size()) {
 553                 //cout << "\n*****nodesLeft*****\n";
 554                 //for(unsigned int i=0; i<nodesLeft.size(); ++i) {
 555                         //cout << nodesLeft[i]->nodeID << '\n';
 556                 //}
 557                 //cout << "*******************\n\n";
 558                 nPtr = *nodesLeft.begin();              // Thought - definate optimization possibilities here in the choice of which nodes we process first.
 559                 nodesLeft.erase(nodesLeft.begin());
 560                 //cout << "Walking out from node " << nPtr->nodeID << '\n';
 561                 for(unsigned int i=0; i<nPtr->arcs.size(); ++i) {
 562                         //cout << "ARC TO " << ((nPtr->arcs[i]->n1 == nPtr->nodeID) ? nPtr->arcs[i]->n2 : nPtr->arcs[i]->n1) << '\n';
 563                 }
 564                 if((solution_found) && (solution_cost <= pathMap[nPtr->nodeID]->cost)) {
 565                         // Do nothing - we've already found a solution and this partial path is already more expensive
 566                 } else {
 567                         // This path could still be better than the current solution - check it out
 568                         for(unsigned int i=0; i<(nPtr->arcs.size()); i++) {
 569                                 // Map the new path against the end node, ie. *not* the one we just started with.
 570                                 unsigned int end_nodeID = ((nPtr->arcs[i]->n1 == nPtr->nodeID) ? nPtr->arcs[i]->n2 : nPtr->arcs[i]->n1);
 571                                 //cout << "end_nodeID = " << end_nodeID << '\n';
 572                                 //cout << "pathMap size is " << pathMap.size() << '\n';
 573                                 if(end_nodeID == nPtr->nodeID) {
 574                                         //cout << "Circular arc!\n";
 575                                         // Then its a circular arc - don't bother!!
 576                                         //nPtr->arcs.erase(nPtr->arcs.begin() + i);
 577                                 } else {
 578                                         // see if the end node is already in the map or not
 579                                         if(pathMap.find(end_nodeID) == pathMap.end()) {
 580                                                 //cout << "Not in the map" << endl;;
 581                                                 // Not in the map - easy!
 582                                                 pathPtr = new a_path;
 583                                                 pathsCreated++;
 584                                                 *pathPtr = *pathMap[nPtr->nodeID];      // *copy* the path
 585                                                 pathPtr->path.push_back(nPtr->arcs[i]);
 586                                                 pathPtr->path.push_back(network[end_nodeID]);
 587                                                 pathPtr->cost += nPtr->arcs[i]->distance;
 588                                                 pathMap[end_nodeID] = pathPtr;
 589                                                 nodesLeft.push_back(network[end_nodeID]);       // By definition this can't be in the list already, or
 590                                                 // it would also have been in the map and hence OR'd with this one.
 591                                                 if(end_nodeID == B->nodeID) {
 592                                                         //cout << "Solution found!!!" << endl;
 593                                                         // Since this node wasn't in the map this is by definition the first solution
 594                                                         solution_cost = pathPtr->cost;
 595                                                         solution_path = *pathPtr;
 596                                                         solution_found = true;
 597                                                 }
 598                                         } else {
 599                                                 //cout << "Already in the map" << endl;
 600                                                 // In the map - not so easy - need to get rid of an arc from the higher cost one.
 601                                                 //cout << "Current cost of node " << end_nodeID << " is " << pathMap[end_nodeID]->cost << endl;
 602                                                 int newCost = pathMap[nPtr->nodeID]->cost + nPtr->arcs[i]->distance;
 603                                                 //cout << "New cost is of node " << nPtr->nodeID << " is " << newCost << endl;
 604                                                 if(newCost >= pathMap[end_nodeID]->cost) {
 605                                                         // No need to do anything.
 606                                                         //cout << "Not doing anything!" << endl;
 607                                                 } else {
 608                                                         delete pathMap[end_nodeID];
 609                                                         pathsCreated--;
 610
 611                                                         pathPtr = new a_path;
 612                                                         pathsCreated++;
 613                                                         *pathPtr = *pathMap[nPtr->nodeID];      // *copy* the path
 614                                                         pathPtr->path.push_back(nPtr->arcs[i]);
 615                                                         pathPtr->path.push_back(network[end_nodeID]);
 616                                                         pathPtr->cost += nPtr->arcs[i]->distance;
 617                                                         pathMap[end_nodeID] = pathPtr;
 618
 619                                                         // We need to add this node to the list-to-do again to force a recalculation
 620                                                         // onwards from this node with the new lower cost to node cost.
 621                                                         nodesLeft.push_back(network[end_nodeID]);
 622
 623                                                         if(end_nodeID == B->nodeID) {
 624                                                                 //cout << "Solution found!!!" << endl;
 625                                                                 // Need to check if there is a previous better solution
 626                                                                 if((solution_cost < 0) || (pathPtr->cost < solution_cost)) {
 627                                                                         solution_cost = pathPtr->cost;
 628                                                                         solution_path = *pathPtr;
 629                                                                         solution_found = true;
 630                                                                 }
 631                                                         }
 632                                                 }
 633                                         }
 634                                 }
 635                         }
 636                 }
 637         }
 638
 639         // delete all the paths before returning
 640         shortest_path_map_iterator spItr = pathMap.begin();
 641         while(spItr != pathMap.end()) {
 642                 if(spItr->second != NULL) {
 643                         delete spItr->second;
 644                         --pathsCreated;
 645                 }
 646                 ++spItr;
 647         }
 648
 649         //cout << "pathsCreated = " << pathsCreated << '\n';
 650         if(pathsCreated > 0) {
 651                 SG_LOG(SG_ATC, SG_ALERT, "WARNING - Possible memory leak in FGGround::GetShortestPath\n\
 652                                                                           Please report to flightgear-devel@flightgear.org\n");
 653         }
 654
 655         //cout << (solution_found ? "Result: solution found\n" : "Result: no solution found\n");
 656         return(solution_path.path);             // TODO - we really ought to have a fallback position incase a solution isn't found.
 657 }
 658
 659
 660
 661 // Randomly or otherwise populate some of the gates with parked planes
 662 // (might eventually be done by the AIMgr if and when lots of AI traffic is generated)
 663
 664 // Return a list of exits from a given runway
 665 // It is up to the calling function to check for non-zero size of returned array before use
 666 node_array_type FGGround::GetExits(const string& rwyID) {
 667         // FIXME - get a 07L or similar in here and we're stuffed!!!
 668         return(runways[atoi(rwyID.c_str())].exits);
 669 }
 670
 671 void FGGround::RequestDeparture(const PlaneRec& plane, FGAIEntity* requestee) {
 672         // For now we'll just automatically clear all planes to the runway hold.
 673         // This communication needs to be delayed 20 sec or so from receiving the request.
 674         // Even if display=false we still need to start the timer in case display=true when communication starts.
 675         // We also need to bear in mind we also might have other outstanding communications, although for now we'll punt that issue!
 676         // FIXME - sort the above!
 677
 678         // HACK - assume that anything requesting departure is new for now - FIXME LATER
 679         GroundRec* g = new GroundRec;
 680         g->plane = plane;
 681         g->planePtr = requestee;
 682         g->taxiRequestOutstanding = true;
 683         g->clearanceCounter = 0;
 684         g->cleared = false;
 685         g->incoming = false;
 686         // TODO - need to handle the next 3 as well
 687     //Point3D current_pos;
 688     //node* destination;
 689     //node* last_clearance;
 690
 691         ground_traffic.push_back(g);
 692 }
 693
 694 #if 0
 695 void FGGround::NewArrival(plane_rec plane) {
 696         // What are we going to do here?
 697         // We need to start a new ground_rec and add the plane_rec to it
 698         // We need to decide what gate we are going to clear it to.
 699         // Then we need to add clearing it to that gate to the pending transmissions queue? - or simply transmit?
 700         // Probably simply transmit for now and think about a transmission queue later if we need one.
 701         // We might need one though in order to add a little delay for response time.
 702         ground_rec* g = new ground_rec;
 703         g->plane_rec = plane;
 704         g->current_pos = ConvertWGS84ToXY(plane.pos);
 705         g->node = GetNode(g->current_pos);  // TODO - might need to sort out node/arc here
 706         AssignGate(g);
 707         g->cleared = false;
 708         ground_traffic.push_back(g);
 709         NextClearance(g);
 710 }
 711
 712 void FGGround::NewContact(plane_rec plane) {
 713         // This is a bit of a convienience function at the moment and is likely to change.
 714         if(at a gate or apron)
 715                 NewDeparture(plane);
 716         else
 717                 NewArrival(plane);
 718 }
 719
 720 void FGGround::NextClearance(ground_rec &g) {
 721         // Need to work out where we can clear g to.
 722         // Assume the pilot doesn't need progressive instructions
 723         // We *should* already have a gate or holding point assigned by the time we get here
 724         // but it wouldn't do any harm to check.
 725
 726         // For now though we will hardwire it to clear to the final destination.
 727 }
 728
 729 void FGGround::AssignGate(ground_rec &g) {
 730         // We'll cheat for now - since we only have the user's aircraft and a couple of airports implemented
 731         // we'll hardwire the gate!
 732         // In the long run the logic of which gate or area to send the plane to could be somewhat non-trivial.
 733 }
 734 #endif //0
 735