#include STL_FSTREAM
#include "ground.hxx"
+#include "ATCutils.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;
networkLoadOK = false;
// 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";
} // 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")) {
} // 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';
// Next we need to decide where its going.
}
-// 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 !!!!
+// 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]);
+ }
}
// 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;
+// 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));
+};
- // 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;
+// 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_GENERAL, 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
// In the long run the logic of which gate or area to send the plane to could be somewhat non-trivial.
}
#endif //0
+
typedef arc_array_type::const_iterator arc_array_const_iterator;
struct node : public ground_network_element {
+ node();
+ ~node();
+
unsigned int nodeID; //each node in an airport needs a unique ID number - this is ZERO-BASED to match array position
Point3D pos;
Point3D orthoPos;
double heading; // The direction the parked-up plane should point in degrees
};
-typedef vector < Gate > gate_vec_type;
+typedef vector < Gate* > gate_vec_type;
typedef gate_vec_type::iterator gate_vec_iterator;
typedef gate_vec_type::const_iterator gate_vec_const_iterator;
// A map of gate vs. the logical (internal FGFS) gate ID
-typedef map < int, Gate > gate_map_type;
+typedef map < int, Gate* > gate_map_type;
typedef gate_map_type::iterator gate_map_iterator;
typedef gate_map_type::const_iterator gate_map_const_iterator;
//////////////////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////
+//
+// Stuff for the shortest-path algorithms
+struct a_path {
+ a_path();
+
+ ground_network_path_type path;
+ int cost;
+};
+
+// Paths mapped by nodeID reached so-far
+typedef map < unsigned int, a_path* > shortest_path_map_type;
+typedef shortest_path_map_type::iterator shortest_path_map_iterator;
+
+// Nodes mapped by their ID
+//typedef map < unsigned int, node* > node_map_type;
+//typedef node_map_type::iterator node_map_iterator;
+////////////////////////////////////////////////
+
// Planes active within the ground network.
// somewhere in the ATC/AI system we are going to have defined something like
// typedef struct plane_rec
// Return a suitable gate (maybe this should be a list of suitable gates so the plane or controller can choose the closest one)
void ReturnGate(Gate &gate, GateType type);
- //The following two functions have been made public for now but may go private with a higher level accessor at some point
- // Return the internal ID of a random, suitable, unused gate
- // For now we are simply implementing as any random unused gate
- int GetRandomGateID();
- // Return a pointer to a node based on the gate ID
- Gate* GetGateNode(int gateID);
+ // Return a pointer to an unused gate
+ Gate* GetGateNode();
// Runway stuff - this might change in the future.
// Get a list of exits from a given runway
// Parse a runway exit string and push the supplied node pointer onto the runway exit list
void ParseRwyExits(node* np, char* es);
+
+ // 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.
+ // TODO - modify to return a suitable gate based on aircraft size/weight.
+ int GetRandomGateID();
+
+ // A shortest path algorithm sort of from memory (I can't find the bl&*dy book again!)
+ ground_network_path_type GetShortestPath(node* A, node* B);
};
#endif // _FG_GROUND_HXX
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