]> git.mxchange.org Git - flightgear.git/blobdiff - src/ATC/ground.cxx
Get rid of the double comma's for the file section of the generic protocol also.
[flightgear.git] / src / ATC / ground.cxx
index f713a69e71b758112c06dc0c7080c3dba708a08c..3e2e0f68b95268f04942e872575189f7d27bf943 100644 (file)
 #include STL_FSTREAM
 
 #include "ground.hxx"
+#include "ATCmgr.hxx"
+#include "ATCutils.hxx"
+#include "ATCdisplay.hxx"
+#include "AILocalTraffic.hxx"
 
 SG_USING_STD(ifstream);
 SG_USING_STD(cout);
 
+node::node() {
+}
+
+node::~node() {
+       for(unsigned int i=0; i < arcs.size(); ++i) {
+               delete arcs[i];
+       }
+}
+
+// Make sure that a_path.cost += distance is safe from the moment it's created.
+a_path::a_path() {
+       cost = 0;
+}
+
 FGGround::FGGround() {
-       display = false;
+       ATCmgr = globals->get_ATC_mgr();
+       _type = GROUND;
+       networkLoadOK = false;
+       ground_traffic.erase(ground_traffic.begin(), ground_traffic.end());
+       ground_traffic_itr = ground_traffic.begin();
+       
+       // Init the property nodes - TODO - need to make sure we're getting surface winds.
+       wind_from_hdg = fgGetNode("/environment/wind-from-heading-deg", true);
+       wind_speed_knots = fgGetNode("/environment/wind-speed-kt", true);
+       
+       // TODO - get the actual airport elevation
+       aptElev = 0.0;
+}
+
+FGGround::FGGround(string id) {
+       ATCmgr = globals->get_ATC_mgr();
        networkLoadOK = false;
+       ground_traffic.erase(ground_traffic.begin(), ground_traffic.end());
+       ground_traffic_itr = ground_traffic.begin();
+       ident = id;
+       
+       // Init the property nodes - TODO - need to make sure we're getting surface winds.
+       wind_from_hdg = fgGetNode("/environment/wind-from-heading-deg", true);
+       wind_speed_knots = fgGetNode("/environment/wind-speed-kt", true);
+       
+       // TODO - get the actual airport elevation
+       aptElev = 0.0;
 }
 
 FGGround::~FGGround() {
@@ -63,22 +106,28 @@ void FGGround::ParseRwyExits(node* np, char* es) {
 // Return true if successfull.
 // TODO - currently the file is assumed to reside in the base/ATC directory.
 // This might change to something more thought out in the future.
+// NOTE - currently it is assumed that all nodes are loaded before any arcs.
+// It won't work ATM if this doesn't hold true.
 bool FGGround::LoadNetwork() {
        node* np;
        arc* ap;
        Gate* gp;
        
+       int gateCount = 0;      // This is used to allocate gateID's from zero upwards
+       // This may well change in the future - probably to reading in the real-world
+       // gate numbers from file.
+       
        ifstream fin;
        SGPath path = globals->get_fg_root();
        //string taxiPath = "ATC/" + ident + ".taxi";
        string taxiPath = "ATC/KEMT.taxi";      // FIXME - HARDWIRED FOR TESTING
        path.append(taxiPath);
        
-       SG_LOG(SG_GENERAL, SG_INFO, "Trying to read taxiway data for " << ident << "...");
+       SG_LOG(SG_ATC, SG_INFO, "Trying to read taxiway data for " << ident << "...");
        //cout << "Trying to read taxiway data for " << ident << "..." << endl;
        fin.open(path.c_str(), ios::in);
        if(!fin) {
-               SG_LOG(SG_GENERAL, SG_ALERT, "Unable to open taxiway data input file " << path.c_str());
+               SG_LOG(SG_ATC, SG_ALERT, "Unable to open taxiway data input file " << path.c_str());
                //cout << "Unable to open taxiway data input file " << path.c_str() << endl;
                return(false);
        }
@@ -90,7 +139,7 @@ bool FGGround::LoadNetwork() {
                // Node, arc, or [End]?
                //cout << "Read in ground network element type = " << buf << endl;
                if(!strcmp(buf, "[End]")) {             // TODO - maybe make this more robust to spelling errors by just looking for '['
-                       SG_LOG(SG_GENERAL, SG_INFO, "Done reading " << path.c_str() << endl);
+                       SG_LOG(SG_ATC, SG_INFO, "Done reading " << path.c_str() << endl);
                        break;
                } else if(!strcmp(buf, "N")) {
                        // Node
@@ -112,28 +161,29 @@ bool FGGround::LoadNetwork() {
                        } else if(!strcmp(buf, "H")) {
                                np->type = HOLD;
                        } else {
-                               cout << "**** ERROR ***** Unknown node type in taxi network...\n";
+                               SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown node type in taxi network...\n");
                                delete np;
                                return(false);
                        }
                        fin >> buf;             // rwy exit information - gets parsed later - FRAGILE - will break if buf is reused.
                        // Now the name
+                       fin >> ch;      // strip the leading " off
                        np->name = "";
                        while(1) {
                                fin.unsetf(ios::skipws);
                                fin >> ch;
-                               np->name += ch;
                                if((ch == '"') || (ch == 0x0A)) {
                                        break;
                                }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
+                               np->name += ch;
                        }
                        fin.setf(ios::skipws);
                        network.push_back(np);
                        // FIXME - fragile - replies on buf not getting modified from exits read to here
                        // see if we also need to push it onto the runway exit list
-                       cout << "strlen(buf) = " << strlen(buf) << endl;
+                       //cout << "strlen(buf) = " << strlen(buf) << endl;
                        if(strlen(buf) > 2) {
-                               cout << "Calling ParseRwyExits for " << buf << endl;
+                               //cout << "Calling ParseRwyExits for " << buf << endl;
                                ParseRwyExits(np, buf);
                        }
                } else if(!strcmp(buf, "A")) {
@@ -149,7 +199,7 @@ bool FGGround::LoadNetwork() {
                        } else if(!strcmp(buf, "T")) {
                                ap->type = TAXIWAY;
                        } else {
-                               cout << "**** ERROR ***** Unknown arc type in taxi network...\n";
+                               SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown arc type in taxi network...\n");
                                delete ap;
                                return(false);
                        }
@@ -160,7 +210,7 @@ bool FGGround::LoadNetwork() {
                        } else if(!strcmp(buf, "N")) {
                                ap->directed = false;
                        } else {
-                               cout << "**** ERROR ***** Unknown arc directed value in taxi network - should be Y/N !!!\n";
+                               SG_LOG(SG_ATC, SG_ALERT, "**** ERROR ***** Unknown arc directed value in taxi network - should be Y/N !!!\n");
                                delete ap;
                                return(false);
                        }                       
@@ -175,6 +225,8 @@ bool FGGround::LoadNetwork() {
                                }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
                        }
                        fin.setf(ios::skipws);
+                       ap->distance = (int)dclGetHorizontalSeparation(network[ap->n1]->pos, network[ap->n2]->pos);
+                       //cout << "Distance  = " << ap->distance << '\n';
                        network[ap->n1]->arcs.push_back(ap);
                        network[ap->n2]->arcs.push_back(ap);
                } else if(!strcmp(buf, "G")) {
@@ -203,10 +255,14 @@ bool FGGround::LoadNetwork() {
                                }   // we shouldn't need the 0x0A but it makes a nice safely in case someone leaves off the "
                        }
                        fin.setf(ios::skipws);
+                       gp->id = gateCount;             // Warning - this will likely change in the future.
+                       gp->used = false;
                        network.push_back(gp);
+                       gates[gateCount] = gp;
+                       gateCount++;
                } else {
                        // Something has gone seriously pear-shaped
-                       cout << "********* ERROR - unknown ground network element type... aborting read of " << path.c_str() << '\n';
+                       SG_LOG(SG_ATC, SG_ALERT, "********* ERROR - unknown ground network element type... aborting read of " << path.c_str() << '\n');
                        return(false);
                }
                
@@ -216,17 +272,19 @@ bool FGGround::LoadNetwork() {
 }
 
 void FGGround::Init() {
-       display = false;
-       
-       // For now we'll hardwire the threshold end
-       Point3D P010(-118.037483, 34.081358, 296 * SG_FEET_TO_METER);
-       double hdg = 25.32;
-       ortho.Init(P010, hdg);
+       untowered = false;
        
+       // Figure out which is the active runway - TODO - it would be better to have ground call tower
+       // for runway operation details, but at the moment we can't guarantee that tower control at a given airport
+       // will be initialised before ground so we can't do that.
+       DoRwyDetails();
+       //cout << "In FGGround::Init, active rwy is " << activeRwy << '\n';
+       ortho.Init(rwy.threshold_pos, rwy.hdg);
+
        networkLoadOK = LoadNetwork();
 }
 
-void FGGround::Update() {
+void FGGround::Update(double dt) {
        // Each time step, what do we need to do?
        // We need to go through the list of outstanding requests and acknowedgements
        // and process at least one of them.
@@ -238,119 +296,360 @@ void FGGround::Update() {
        // Lets take the example of a plane which has just contacted ground
        // following landing - presumably requesting where to go?
        // First we need to establish the position of the plane within the logical network.
-       // Next we need to decide where its going. 
+       // Next we need to decide where its going.
+       
+       if(ground_traffic.size()) {
+               if(ground_traffic_itr == ground_traffic.end()) {
+                       ground_traffic_itr = ground_traffic.begin();
+               }
+               
+               //Process(*ground_traffic_itr);
+               GroundRec* g = *ground_traffic_itr;
+               if(g->taxiRequestOutstanding) {
+                       double responseTime = 10.0;             // seconds - this should get more sophisticated at some point
+                       if(g->clearanceCounter > responseTime) {
+                               // DO CLEARANCE
+                               // TODO - move the mechanics of making up the transmission out of the main Update(...) routine.
+                               string trns = "";
+                               trns += g->plane.callsign;
+                               trns += " taxi holding point runway ";  // TODO - add the holding point name
+                               // eg " taxi holding point G2 runway "
+                               trns += ConvertRwyNumToSpokenString(activeRwy);
+                               if(_display) {
+                                       globals->get_ATC_display()->RegisterSingleMessage(trns, 0);
+                               }
+                               g->planePtr->RegisterTransmission(1);   // cleared to taxi
+                               g->clearanceCounter = 0.0;
+                               g->taxiRequestOutstanding = false;
+                       } else {
+                               g->clearanceCounter += (dt * ground_traffic.size());
+                       }
+               } else if(((FGAILocalTraffic*)(g->planePtr))->AtHoldShort()) {          // That's a hack - eventually we should monitor actual position
+                       // HACK ALERT - the automatic cast to AILocalTraffic has to go once we have other sorts working!!!!! FIXME TODO
+                       // NOTE - we don't need to do the contact tower bit unless we have separate tower and ground
+                       string trns = g->plane.callsign;
+                       trns += " contact Tower ";
+                       double f = globals->get_ATC_mgr()->GetFrequency(ident, TOWER) / 100.0;
+                       char buf[10];
+                       sprintf(buf, "%.2f", f);
+                       trns += buf;
+                       if(_display) {
+                               globals->get_ATC_display()->RegisterSingleMessage(trns, 0);
+                       }
+                       g->planePtr->RegisterTransmission(2);   // contact tower
+                       delete *ground_traffic_itr;
+                       ground_traffic.erase(ground_traffic_itr);
+                       ground_traffic_itr = ground_traffic.begin();
+               }                               
+               ++ground_traffic_itr;
+       }
+       
+       // Call the base class update for the response time handling.
+       FGATC::Update(dt);
 }
 
-// FIXME - at the moment this assumes there is at least one gate and crashes if none
-// FIXME - In fact, at the moment this routine doesn't work at all and hence is munged to always return Gate 1 !!!!
+// Figure out which runways are active.
+// For now we'll just be simple and do one active runway - eventually this will get much more complex
+// Copied from FGTower - TODO - it would be better to implement this just once, and have ground call tower
+// for runway operation details, but at the moment we can't guarantee that tower control at a given airport
+// will be initialised before ground so we can't do that.
+void FGGround::DoRwyDetails() {
+       //cout << "GetRwyDetails called" << endl;
+       
+       // Based on the airport-id and wind get the active runway
+       
+       //wind
+       double hdg = wind_from_hdg->getDoubleValue();
+       double speed = wind_speed_knots->getDoubleValue();
+       hdg = (speed == 0.0 ? 270.0 : hdg);
+       //cout << "Heading = " << hdg << '\n';
+       
+       FGRunway runway;
+       bool rwyGood = globals->get_runways()->search(ident, int(hdg), &runway);
+       if(rwyGood) {
+               activeRwy = runway.rwy_no;
+               rwy.rwyID = runway.rwy_no;
+               SG_LOG(SG_ATC, SG_INFO, "In FGGround, active runway for airport " << ident << " is " << activeRwy);
+               
+               // Get the threshold position
+               double other_way = runway.heading - 180.0;
+               while(other_way <= 0.0) {
+                       other_way += 360.0;
+               }
+       // move to the +l end/center of the runway
+               //cout << "Runway center is at " << runway.lon << ", " << runway.lat << '\n';
+       Point3D origin = Point3D(runway.lon, runway.lat, aptElev);
+               Point3D ref = origin;
+       double tshlon, tshlat, tshr;
+               double tolon, tolat, tor;
+               rwy.length = runway.length * SG_FEET_TO_METER;
+       geo_direct_wgs_84 ( aptElev, ref.lat(), ref.lon(), other_way, 
+                               rwy.length / 2.0 - 25.0, &tshlat, &tshlon, &tshr );
+       geo_direct_wgs_84 ( aptElev, ref.lat(), ref.lon(), runway.heading, 
+                               rwy.length / 2.0 - 25.0, &tolat, &tolon, &tor );
+               // Note - 25 meters in from the runway end is a bit of a hack to put the plane ahead of the user.
+               // now copy what we need out of runway into rwy
+       rwy.threshold_pos = Point3D(tshlon, tshlat, aptElev);
+               Point3D takeoff_end = Point3D(tolon, tolat, aptElev);
+               //cout << "Threshold position = " << tshlon << ", " << tshlat << ", " << aptElev << '\n';
+               //cout << "Takeoff position = " << tolon << ", " << tolat << ", " << aptElev << '\n';
+               rwy.hdg = runway.heading;
+               // Set the projection for the local area based on this active runway
+               ortho.Init(rwy.threshold_pos, rwy.hdg); 
+               rwy.end1ortho = ortho.ConvertToLocal(rwy.threshold_pos);        // should come out as zero
+               rwy.end2ortho = ortho.ConvertToLocal(takeoff_end);
+       } else {
+               SG_LOG(SG_ATC, SG_ALERT, "Help  - can't get good runway in FGTower!!");
+               activeRwy = "NN";
+       }
+}
+
+// Return a random gate ID of an unused gate.
+// Two error values may be returned and must be checked for by the calling function:
+// -2 signifies that no gates exist at this airport.
+// -1 signifies that all gates are currently full.
 int FGGround::GetRandomGateID() {
-       //cout << "GetRandomGateID called" << endl;
-       return(1);
+       // Check that this airport actually has some gates!!
+       if(!gates.size()) {
+               return(-2);
+       }
 
        gate_vec_type gateVec;
-       //gate_vec_iterator gateVecItr;
        int num = 0;
        int thenum;
        int ID;
        
        gatesItr = gates.begin();
        while(gatesItr != gates.end()) {
-               if(gatesItr->second.used == false) {
+               if((gatesItr->second)->used == false) {
                        gateVec.push_back(gatesItr->second);
                        num++;
                }
                ++gatesItr;
        }
+
+       // Check that there are some unused gates!
+       if(!gateVec.size()) {
+               return(-1);
+       }
        
        // Randomly select one from the list
+       sg_srandom_time();
        thenum = (int)(sg_random() * gateVec.size());
-       ID = gateVec[thenum].id;
-       //cout << "Returning gate ID " << ID << " from GetRandomGateID" << endl;
+       ID = gateVec[thenum]->id;
+       
        return(ID);
 }
 
-// Return a pointer to a gate node based on the gate ID
-Gate* FGGround::GetGateNode(int gateID) {
-       //TODO - ought to add some sanity checking here - ie does a gate of this ID exist?!
-       return(&(gates[gateID]));
+// Return a pointer to an unused gate node
+Gate* FGGround::GetGateNode() {
+       int id = GetRandomGateID();
+       if(id < 0) {
+               return(NULL);
+       } else {
+               return(gates[id]);
+       }
 }
 
+
+node* FGGround::GetHoldShortNode(string rwyID) {
+       return(NULL);   // TODO - either implement me or remove me!!!
+}
+
+
+// WARNING - This is hardwired to my prototype logical network format
+// and will almost certainly change when Bernie's stuff comes on-line.
+// Returns NULL if it can't find a valid node.
+node* FGGround::GetThresholdNode(string rwyID) {
+       // For now go through all the nodes and parse their names
+       // Maybe in the future we'll map threshold nodes by ID
+       //cout << "Size of network is " << network.size() << '\n';
+       for(unsigned int i=0; i<network.size(); ++i) {
+               //cout << "Name = " << network[i]->name << '\n';
+               if(network[i]->name.size()) {
+                       string s = network[i]->name;
+                       // Warning - the next bit is fragile and dependent on my current naming scheme
+                       //cout << "substr = " << s.substr(0,3) << '\n';
+                       //cout << "size of s = " << s.size() << '\n'; 
+                       if(s.substr(0,3) == "rwy") {
+                               //cout << "subsubstr = " << s.substr(4, s.size() - 4) << '\n';
+                               if(s.substr(4, s.size() - 4) == rwyID) {
+                                       return network[i];
+                               }
+                       }
+               }
+       }
+       return NULL;
+}
+
+
 // Get a path from a point on a runway to a gate
+// TODO !!
 
 // Get a path from a node to another node
 // Eventually we will need complex algorithms for this taking other traffic,
-// shortest path and suitable paths into accout.  For now we're going to hardwire for KEMT!!!!
-ground_network_path_type FGGround::GetPath(node* A, node* B) {
-       ground_network_path_type path;
-       //arc_array_iterator arcItr;
-       //bool found;
-
-       // VERY HARDWIRED - this hardwires a path from the far end of R01 to Gate 1.
-       // In fact in real life the area between R01/19 and Taxiway Alpha at KEMT is tarmaced and planes
-       // are supposed to exit the rwy asap.
-       // OK - for now very hardwire this for testing
-       path.push_back(network[1]);
-       path.push_back(network[1]->arcs[1]);    // ONLY BECAUSE WE KNOW THIS IS THE ONE !!!!!
-       path.push_back(network[3]);
-       path.push_back(network[3]->arcs[1]);
-       path.push_back(network[5]);
-       path.push_back(network[5]->arcs[0]);
-       path.push_back(network[4]);
-       path.push_back(network[4]->arcs[2]);
-       path.push_back(network[6]);
-       path.push_back(network[6]->arcs[2]);
-       path.push_back(network[7]);                             // THE GATE!!  Note that for now we're not even looking at the requested exit and gate passed in !!!!!
-
-#if 0  
-       // In this hardwired scheme there are two possibilities - taxiing from rwy to gate or gate to rwy.
-       if(B->type == GATE) {
-               //return an inward path
-               path.push_back(A);
-               // In this hardwired scheme we know A is a rwy exit and should have one taxiway arc only
-               // THIS WILL NOT HOLD TRUE IN THE GENERAL CASE
-               arcItr = A->arcs.begin();
-               found = false;
-               while(arcItr != A->arcs.end()) {
-                       if(arcItr->type == TAXIWAY) {
-                               path.push_back(&(*arcItr));
-                               found = true;
-                               break;
-                       }
-               }
-               if(found == false) {
-                       //cout << "AI/ATC SUBSYSTEM ERROR - no taxiway from runway exit in airport.cxx" << endl;
+// shortest path and suitable paths into accout.
+// For now we'll just call the shortest path algorithm.
+ground_network_path_type FGGround::GetPath(node* A, node* B) { 
+       return(GetShortestPath(A, B));
+};
+
+// Get a path from a node to a runway threshold
+ground_network_path_type FGGround::GetPath(node* A, string rwyID) {
+       node* b = GetThresholdNode(rwyID);
+       if(b == NULL) {
+               SG_LOG(SG_ATC, SG_ALERT, "ERROR - unable to find path to runway theshold in ground.cxx for airport " << ident << '\n');
+               ground_network_path_type emptyPath;
+               emptyPath.erase(emptyPath.begin(), emptyPath.end());
+               return(emptyPath);
+       }
+       return GetShortestPath(A, b);
+}
+
+// Get a path from a node to a runway hold short point
+// Bit of a hack this at the moment!
+ground_network_path_type FGGround::GetPathToHoldShort(node* A, string rwyID) {
+       ground_network_path_type path = GetPath(A, rwyID);
+       path.pop_back();        // That should be the threshold stripped of 
+       path.pop_back();        // and that should be the arc from hold short to threshold
+       // This isn't robust though - TODO - implement properly!
+       return(path);
+}
+
+// A shortest path algorithm from memory (ie. I can't find the bl&*dy book again!)
+// I'm sure there must be enchancements that we can make to this, such as biasing the
+// order in which the nodes are searched out from in favour of those geographically
+// closer to the destination.
+// Note that we are working with the master set of nodes and arcs so we mustn't change
+// or delete them -  we only delete the paths that we create during the algorithm.
+ground_network_path_type FGGround::GetShortestPath(node* A, node* B) {
+       a_path* pathPtr;
+       shortest_path_map_type pathMap;
+       node_array_type nodesLeft;
+       
+       // Debugging check
+       int pathsCreated = 0;
+       
+       // Initialise the algorithm
+       nodesLeft.push_back(A);
+       pathPtr = new a_path;
+       pathsCreated++;
+       pathPtr->path.push_back(A);
+       pathPtr->cost = 0;
+       pathMap[A->nodeID] = pathPtr;
+       bool solution_found = false;    // Flag to indicate that at least one candidate path has been found
+       int solution_cost = -1;                 // Cost of current best cost solution.  -1 indicates no solution found yet.
+       a_path solution_path;           
+                                                                                       
+       node* nPtr;     // nPtr is used to point to the node we are currently working with
+       
+       while(nodesLeft.size()) {
+               //cout << "\n*****nodesLeft*****\n";
+               //for(unsigned int i=0; i<nodesLeft.size(); ++i) {
+                       //cout << nodesLeft[i]->nodeID << '\n';
+               //}
+               //cout << "*******************\n\n";
+               nPtr = *nodesLeft.begin();              // Thought - definate optimization possibilities here in the choice of which nodes we process first.
+               nodesLeft.erase(nodesLeft.begin());
+               //cout << "Walking out from node " << nPtr->nodeID << '\n';
+               for(unsigned int i=0; i<nPtr->arcs.size(); ++i) {
+                       //cout << "ARC TO " << ((nPtr->arcs[i]->n1 == nPtr->nodeID) ? nPtr->arcs[i]->n2 : nPtr->arcs[i]->n1) << '\n';
                }
-               // Then push back the start of taxiway node
-               // Then push back the taxiway arc
-               arcItr = A->arcs.begin();
-               found = false;
-               while(arcItr != A->arcs.end()) {
-                       if(arcItr->type == TAXIWAY) { // FIXME - OOPS - two taxiways go off this node
-                               // How are we going to differentiate, apart from one called Alpha.
-                               // I suppose eventually the traversal algorithms will select.
-                               path.push_back(&(*arcItr));
-                               found = true;
-                               break;
-               }
+               if((solution_found) && (solution_cost <= pathMap[nPtr->nodeID]->cost)) {
+                       // Do nothing - we've already found a solution and this partial path is already more expensive
+               } else {
+                       // This path could still be better than the current solution - check it out
+                       for(unsigned int i=0; i<(nPtr->arcs.size()); i++) {
+                               // Map the new path against the end node, ie. *not* the one we just started with.
+                               unsigned int end_nodeID = ((nPtr->arcs[i]->n1 == nPtr->nodeID) ? nPtr->arcs[i]->n2 : nPtr->arcs[i]->n1);
+                               //cout << "end_nodeID = " << end_nodeID << '\n';
+                               //cout << "pathMap size is " << pathMap.size() << '\n';
+                               if(end_nodeID == nPtr->nodeID) {
+                                       //cout << "Circular arc!\n";
+                                       // Then its a circular arc - don't bother!!
+                                       //nPtr->arcs.erase(nPtr->arcs.begin() + i);
+                               } else {
+                                       // see if the end node is already in the map or not
+                                       if(pathMap.find(end_nodeID) == pathMap.end()) {
+                                               //cout << "Not in the map" << endl;;
+                                               // Not in the map - easy!
+                                               pathPtr = new a_path;
+                                               pathsCreated++;
+                                               *pathPtr = *pathMap[nPtr->nodeID];      // *copy* the path
+                                               pathPtr->path.push_back(nPtr->arcs[i]);
+                                               pathPtr->path.push_back(network[end_nodeID]);
+                                               pathPtr->cost += nPtr->arcs[i]->distance;
+                                               pathMap[end_nodeID] = pathPtr;
+                                               nodesLeft.push_back(network[end_nodeID]);       // By definition this can't be in the list already, or
+                                               // it would also have been in the map and hence OR'd with this one.
+                                               if(end_nodeID == B->nodeID) {
+                                                       //cout << "Solution found!!!" << endl;
+                                                       // Since this node wasn't in the map this is by definition the first solution
+                                                       solution_cost = pathPtr->cost;
+                                                       solution_path = *pathPtr;
+                                                       solution_found = true;
+                                               }
+                                       } else {
+                                               //cout << "Already in the map" << endl;
+                                               // In the map - not so easy - need to get rid of an arc from the higher cost one.
+                                               //cout << "Current cost of node " << end_nodeID << " is " << pathMap[end_nodeID]->cost << endl;
+                                               int newCost = pathMap[nPtr->nodeID]->cost + nPtr->arcs[i]->distance;
+                                               //cout << "New cost is of node " << nPtr->nodeID << " is " << newCost << endl;
+                                               if(newCost >= pathMap[end_nodeID]->cost) {
+                                                       // No need to do anything.
+                                                       //cout << "Not doing anything!" << endl;
+                                               } else {
+                                                       delete pathMap[end_nodeID];
+                                                       pathsCreated--;
+                                                       
+                                                       pathPtr = new a_path;
+                                                       pathsCreated++;
+                                                       *pathPtr = *pathMap[nPtr->nodeID];      // *copy* the path
+                                                       pathPtr->path.push_back(nPtr->arcs[i]);
+                                                       pathPtr->path.push_back(network[end_nodeID]);
+                                                       pathPtr->cost += nPtr->arcs[i]->distance;
+                                                       pathMap[end_nodeID] = pathPtr;
+                                                       
+                                                       // We need to add this node to the list-to-do again to force a recalculation 
+                                                       // onwards from this node with the new lower cost to node cost.
+                                                       nodesLeft.push_back(network[end_nodeID]);
+                                                       
+                                                       if(end_nodeID == B->nodeID) {
+                                                               //cout << "Solution found!!!" << endl;
+                                                               // Need to check if there is a previous better solution
+                                                               if((solution_cost < 0) || (pathPtr->cost < solution_cost)) {
+                                                                       solution_cost = pathPtr->cost;
+                                                                       solution_path = *pathPtr;
+                                                                       solution_found = true;
+                                                               }
+                                                       }
+                                               }
+                                       }
+                               }
+                       }
                }
-               if(found == false) {
-               //cout << "AI/ATC SUBSYSTEM ERROR - no taxiway from runway exit in airport.cxx" << endl;
+       }
+       
+       // delete all the paths before returning
+       shortest_path_map_iterator spItr = pathMap.begin();
+       while(spItr != pathMap.end()) {
+               if(spItr->second != NULL) {
+                       delete spItr->second;
+                       --pathsCreated;
                }
-               // Then push back the junction node
-               // Planes always face one way in the parking, so depending on which parking exit we have either take it or push back another taxiway node
-               // Repeat if necessary
-               // Then push back the gate B
-               path.push_back(B);
-       } else {
-               //return an outward path
-       }       
-
-       // WARNING TODO FIXME - this is VERY FRAGILE - eg taxi to apron!!! but should be enough to
-       // see an AI plane physically taxi.
-#endif // 0
+               ++spItr;
+       }
        
-       return(path);
-};
+       //cout << "pathsCreated = " << pathsCreated << '\n';
+       if(pathsCreated > 0) {
+               SG_LOG(SG_ATC, SG_ALERT, "WARNING - Possible memory leak in FGGround::GetShortestPath\n\
+                                                                         Please report to flightgear-devel@flightgear.org\n");
+       }
+       
+       //cout << (solution_found ? "Result: solution found\n" : "Result: no solution found\n");
+       return(solution_path.path);             // TODO - we really ought to have a fallback position incase a solution isn't found.
+}
+               
 
 
 // Randomly or otherwise populate some of the gates with parked planes
@@ -358,8 +657,32 @@ ground_network_path_type FGGround::GetPath(node* A, node* B) {
 
 // Return a list of exits from a given runway
 // It is up to the calling function to check for non-zero size of returned array before use
-node_array_type FGGround::GetExits(int rwyID) {
-       return(runways[rwyID].exits);
+node_array_type FGGround::GetExits(string rwyID) {
+       // FIXME - get a 07L or similar in here and we're stuffed!!!
+       return(runways[atoi(rwyID.c_str())].exits);
+}
+
+void FGGround::RequestDeparture(PlaneRec plane, FGAIEntity* requestee) {
+       // For now we'll just automatically clear all planes to the runway hold.
+       // This communication needs to be delayed 20 sec or so from receiving the request.
+       // Even if display=false we still need to start the timer in case display=true when communication starts.
+       // We also need to bear in mind we also might have other outstanding communications, although for now we'll punt that issue!
+       // FIXME - sort the above!
+       
+       // HACK - assume that anything requesting departure is new for now - FIXME LATER
+       GroundRec* g = new GroundRec;
+       g->plane = plane;
+       g->planePtr = requestee;
+       g->taxiRequestOutstanding = true;
+       g->clearanceCounter = 0;
+       g->cleared = false;
+       g->incoming = false;
+       // TODO - need to handle the next 3 as well
+    //Point3D current_pos;
+    //node* destination;
+    //node* last_clearance;
+       
+       ground_traffic.push_back(g);
 }
 
 #if 0
@@ -403,3 +726,4 @@ void FGGround::AssignGate(ground_rec &g) {
        // In the long run the logic of which gate or area to send the plane to could be somewhat non-trivial.
 }
 #endif //0
+