/// <summary>
/// Find the chain of TaxiNodes that represent this runway
/// </summary>
/// <param name="taxiNodes"></param>
/// <param name="taxiEdges"></param>
/// <returns></returns>
private List <TaxiNode> FindNodeChain(IEnumerable <TaxiNode> taxiNodes, IEnumerable <TaxiEdge> taxiEdges)
{
List <TaxiNode> nodes = new List <TaxiNode>();
// Start with the node nearest to the runway lat/lon
TaxiNode currentNode = NearestNode;
nodes.Add(currentNode);
ulong previousNodeId = 0;
do
{
// Now find an edge that is marked as 'runway' and that starts at the current node, but does not lead to the previous node
IEnumerable <TaxiEdge> edgesToNext = taxiEdges.Where(e => e.IsRunway && (e.StartNode.Id == currentNode.Id && e.EndNode.Id != previousNodeId));
if (edgesToNext.Count() == 0)
{
break;
}
TaxiEdge edgeToNext = edgesToNext.First();
if (edgesToNext.Count() > 1)
{
double maxDeviation = double.MaxValue;
foreach (TaxiEdge candidate in edgesToNext)
{
double deviation = VortexMath.TurnAngle(this.Bearing, VortexMath.BearingRadians(currentNode, candidate.EndNode));
if (deviation < maxDeviation)
{
edgeToNext = candidate;
maxDeviation = deviation;
}
}
}
// Keep the current Id as the previous Id
previousNodeId = currentNode.Id;
// And get the new current node
currentNode = taxiNodes.Single(n => n.Id == edgeToNext.EndNode.Id);
if (currentNode != null)
{
nodes.Add(currentNode);
}
}while (currentNode != null);
return(nodes);
}
internal void FindNearestLine(List <LineElement> _lines)
{
double minDist = double.MaxValue;
LineElement leBEst = null;
foreach (LineElement line in _lines)
{
LineElement from = line;
foreach (LineElement seg in line.Segments)
{
LineElement to = seg;
double dStart = VortexMath.DistanceKM(this, from);
if (dStart < minDist)
{
double lineBearing = VortexMath.BearingRadians(from, to);
double turn = VortexMath.AbsTurnAngle(lineBearing, Bearing);
//if (turn < VortexMath.Deg005Rad || turn > VortexMath.PI - VortexMath.Deg005Rad)
{
leBEst = line;
minDist = dStart;
}
}
from = to;
}
}
if (leBEst != null)
{
Logger.Log($"{Name} has a line node at {minDist * 1000:0.000} meters: {leBEst.Latitude * VortexMath.Rad2Deg} {leBEst.Longitude * VortexMath.Rad2Deg}");
}
else
{
Logger.Log($"{Name} has no nearby line node");
}
}
public bool Analyze(IEnumerable <TaxiNode> taxiNodes, IEnumerable <TaxiEdge> taxiEdges)
{
Logger.Log($"---------------------------------------------");
Logger.Log($"Analyzing Runway {Designator}");
Logger.Log($"---------------------------------------------");
// Find the taxi nodes closest to the start of the runway and the displaced start
double shortestDistance = double.MaxValue;
double shortestDisplacedDistance = double.MaxValue;
IEnumerable <TaxiNode> runwayNodes = taxiEdges.Where(te => te.IsRunway).Select(te => te.StartNode).Concat(taxiEdges.Where(te => te.IsRunway).Select(te => te.EndNode)).Distinct();
foreach (TaxiNode node in runwayNodes)
{
// Start with a few sanity cehcks to prevent runways without nodes in the apt.dat fro picking up nodes from nearby runways
double angleFromStart = VortexMath.AbsTurnAngle(Bearing, VortexMath.BearingRadians(this, node));
double d = VortexMath.DistanceKM(node.Latitude, node.Longitude, DisplacedLatitude, DisplacedLongitude);
// A node more than 10m from the runway start should be near the centerline to be accepted
if (d > 0.010 && angleFromStart > VortexMath.Deg005Rad)
{
continue;
}
// Ignore node that are farther away from the runway coordinates than the length of the runway
if (d > Length * 1.1)
{
continue;
}
// Now see if this node is better than the best so far
if (d < shortestDisplacedDistance)
{
shortestDisplacedDistance = d;
DisplacedNode = node;
}
d = VortexMath.DistanceKM(this, node);
if (d < shortestDistance)
{
shortestDistance = d;
NearestNode = node;
}
}
if (NearestNode == null)
{
// The KOKC runway 18 clause...
Logger.Log($"No suitable nodes on the runway found.");
AvailableForTakeOff = false;
AvailableForLanding = false;
return(false);
}
// Find the nodes that make up this runway: first find an edge connected to the nearest node
IEnumerable <TaxiEdge> selectedEdges = taxiEdges.Where(te => te.IsRunway && (te.EndNode.Id == NearestNode.Id || te.StartNode.Id == NearestNode.Id));
if (selectedEdges.Count() == 0)
{
Logger.Log($"No runway edges found.");
AvailableForTakeOff = false;
AvailableForLanding = false;
return(false);
}
// The name of the link gives the name of the runway, use it to retrieve all edges for this runway
string edgeKey = selectedEdges.First().LinkName;
selectedEdges = taxiEdges.Where(te => te.LinkName == edgeKey);
RunwayNodes = FindNodeChain(taxiNodes, selectedEdges);
if (AvailableForTakeOff)
{
FindEntries();
}
else
{
Logger.Log("Not in use for take offs");
}
if (AvailableForLanding)
{
FindExits();
}
else
{
Logger.Log("Not in use for landing");
}
return(true);
}
public void DetermineTaxiOutLocation(IEnumerable <TaxiNode> taxiNodes)
{
double shortestDistance = double.MaxValue;
double bestPushBackLatitude = 0;
double bestPushBackLongitude = 0;
TaxiNode firstAfterPush = null;
TaxiNode alternateAfterPush = null;
TaxiNode fallback = null;
// For gates use the indicated bearings (push back), for others add 180 degrees for straight out
// Then convert to -180...180 range
double adjustedBearing = (LocationType == StartUpLocationType.Gate) ? Bearing : (Bearing + Math.PI);
if (adjustedBearing > Math.PI)
{
adjustedBearing -= (VortexMath.PI2);
}
// Compute the distance (arbitrary units) from each taxi node to the start location
foreach (TaxiNode node in taxiNodes)
{
node.TemporaryDistance = VortexMath.DistanceKM(node, this);
}
// Select the 25 nearest, then from those select only the ones that are in the 180 degree arc of the direction
// we intend to move in from the startpoint
// todo: make both 25 and 180 parameters
IEnumerable <TaxiNode> selectedNodes = taxiNodes.OrderBy(v => v.TemporaryDistance).Take(25);
fallback = selectedNodes.First();
if (fallback.TemporaryDistance < 0.0025)
{
// There is a atc taxi node really close to the parking, try to build pushback path from there
if (fallback.IncomingEdges.Count == 1)
{
TaxiEdge theEdge = fallback.IncomingEdges.FirstOrDefault();
if (theEdge != null)
{
fallback = theEdge.StartNode;
while (fallback.TemporaryDistance < 0.150 && fallback.IncomingEdges.Count <= 2)
{
TaxiEdge nextEdge = fallback.IncomingEdges.FirstOrDefault(e => e.StartNode != theEdge.EndNode);
if (nextEdge == null)
{
break;
}
// This catches the cases at the end of an apron where the only
// link is the actual taxipath already
if (VortexMath.AbsTurnAngle(theEdge.Bearing, nextEdge.Bearing) > VortexMath.Deg060Rad)
{
break;
}
// todo: each node should be added to the parking as 'push back trajectory'
fallback = nextEdge.StartNode;
theEdge = nextEdge;
}
NearestNode = fallback;
AlternateAfterPushBack = null;
PushBackLatitude = fallback.Latitude;
PushBackLongitude = fallback.Longitude;
return;
}
}
}
selectedNodes = selectedNodes.Where(v => Math.Abs(adjustedBearing - VortexMath.BearingRadians(v, this)) < VortexMath.PI05);
// For each qualifying node
// Todo: check this part for tie downs
foreach (TaxiNode v in selectedNodes)
{
// Look at each link coming into it from other nodes
foreach (TaxiEdge incoming in v.IncomingEdges)
{
double pushBackLatitude = 0;
double pushBackLongitude = 0;
// Now find where the 'start point outgoing line' intersects with the taxi link we are currently checking
if (!VortexMath.Intersection(Latitude, Longitude, adjustedBearing,
incoming.StartNode.Latitude, incoming.StartNode.Longitude, incoming.Bearing,
ref pushBackLatitude, ref pushBackLongitude))
{
// If computation fails, try again but now with the link in the other direction.
// Ignoring one way links here, I just want a push back target for now that's close to A link.
if (!VortexMath.Intersection(Latitude, Longitude, adjustedBearing,
incoming.StartNode.Latitude, incoming.StartNode.Longitude, incoming.Bearing + Math.PI,
ref pushBackLatitude, ref pushBackLongitude))
{
// Lines might be parallel, can't find intersection, skip
continue;
}
}
// Great Circles cross twice, if we found the one on the back of the earth, convert it to the
// one on the airport
// Todo: check might fail for airports on the -180/+180 longitude line
if (Math.Abs(pushBackLongitude - Longitude) > 0.25 * Math.PI)
{
pushBackLatitude = -pushBackLatitude;
pushBackLongitude += VortexMath.PI;
if (pushBackLongitude > VortexMath.PI)
{
pushBackLongitude -= VortexMath.PI2;
}
}
// To find the best spot we must know if the found intersection is actually
// on the link or if it is somewhere outside the actual link. These are
// still usefull in some cases
bool foundTargetIsOutsideSegment = false;
// Todo: check might fail for airports on the -180/+180 longitude line
if (pushBackLatitude - incoming.StartNode.Latitude > 0)
{
if (v.Latitude - pushBackLatitude <= 0)
{
foundTargetIsOutsideSegment = true;
}
}
else if (v.Latitude - pushBackLatitude > 0)
{
foundTargetIsOutsideSegment = true;
}
if (pushBackLongitude - incoming.StartNode.Longitude > 0)
{
if (v.Longitude - pushBackLongitude <= 0)
{
foundTargetIsOutsideSegment = true;
}
}
else if (v.Longitude - pushBackLongitude > 0)
{
foundTargetIsOutsideSegment = true;
}
// Ignore links where the taxiout line intercepts at too sharp of an angle if it is
// also outside the actual link.
// todo: Maybe ignore these links right away, saves a lot of calculations
double interceptAngleSharpness = Math.Abs(VortexMath.PI05 - Math.Abs((adjustedBearing - incoming.Bearing) % Math.PI)) / Math.PI;
if (foundTargetIsOutsideSegment && interceptAngleSharpness > 0.4)
{
continue;
}
// for the found location keep track of the distance to it from the start point
// also keep track of the distances to both nodes of the link we are inspecting now
double pushDistance = 0.0;
double distanceSource = VortexMath.DistancePyth(incoming.StartNode.Latitude, incoming.StartNode.Longitude, pushBackLatitude, pushBackLongitude);
double distanceDest = VortexMath.DistancePyth(v.Latitude, v.Longitude, pushBackLatitude, pushBackLongitude);
// If the found point is outside the link, add the distance to the nearest node of
// the link times 2 as a penalty to the actual distance. This prevents pushback point
// candidates that sneak up on the start because of a slight angle in remote link
// from being accepted as best.
TaxiNode nearestVertexIfPushBackOutsideSegment = null;
if (foundTargetIsOutsideSegment)
{
if (distanceSource < distanceDest)
{
pushDistance = distanceSource * 2.0;
nearestVertexIfPushBackOutsideSegment = incoming.StartNode;
}
else
{
pushDistance = distanceDest * 2.0;
nearestVertexIfPushBackOutsideSegment = v;
}
}
// How far is the candidate from the start point?
pushDistance += VortexMath.DistancePyth(Latitude, Longitude, pushBackLatitude, pushBackLongitude);
// See if it is a better candidate
if (pushDistance < shortestDistance)
{
bestPushBackLatitude = pushBackLatitude;
bestPushBackLongitude = pushBackLongitude;
shortestDistance = pushDistance;
// Setting things up for the path calculation that will follow later
if (foundTargetIsOutsideSegment)
{
// The taxi out route will start with a push to the best candidate
// Then move to the 'firstAfterPush' node and from there follow
// the 'shortest' path to the runway
firstAfterPush = nearestVertexIfPushBackOutsideSegment;
alternateAfterPush = null;
}
else
{
// The taxi out route will start with a push to the best candidate
// Then, if the second node in the find 'shortest' path is the alternate
// the first point will be skipped. If the second point is not the alternate,
// the 'firstAfterPush' will be the first indeed and after that the found
// route will be followed.
if (distanceSource < distanceDest)
{
firstAfterPush = incoming.StartNode;
alternateAfterPush = v;
}
else
{
firstAfterPush = v;
alternateAfterPush = incoming.StartNode;
}
}
}
}
}
// All candiates have been considered, post processing the winner:
if (shortestDistance < double.MaxValue)
{
// If there is one, check if it is not too far away from the start. This catches cases where
// a gate at the end of an apron with heading parallel to the apron entry would get a best
// target on the taxiway outside the apron.
double actualDistance = VortexMath.DistanceKM(Latitude, Longitude, bestPushBackLatitude, bestPushBackLongitude);
if (actualDistance > 0.25)
{
// Fix this by pushing to the end point of the entry link
// (If that is actually the nearest node to the parking, but alas...
// this is the default WT3 behaviour anyway)
NearestNode = selectedNodes.First();
AlternateAfterPushBack = null;
PushBackLatitude = NearestNode.Latitude;
PushBackLongitude = NearestNode.Longitude;
}
else
{
// Store the results in the startpoint
PushBackLatitude = bestPushBackLatitude;
PushBackLongitude = bestPushBackLongitude;
NearestNode = firstAfterPush;
AlternateAfterPushBack = alternateAfterPush;
}
}
else
{
// Crude fallback to defautl WT behavoit if nothing was found.
NearestNode = fallback;
AlternateAfterPushBack = null;
PushBackLatitude = NearestNode.Latitude;
PushBackLongitude = NearestNode.Longitude;
}
}
public void Compute()
{
DistanceKM = VortexMath.DistanceKM(StartNode, EndNode);
Bearing = VortexMath.BearingRadians(StartNode, EndNode);
}
/// <summary>
/// Dijkstra... goes through the full network finding shortest path from every node to the target so
/// that afterwards we can cherrypick the starting nodes we are actually interested in.
/// </summary>
/// <param name="nodes">The node network</param>
/// <param name="targetNode">Here do we go now</param>
/// <param name="targetCategory">Minimum Cat (A-F) that needs to be supported by the route</param>
private static void FindShortestPaths(IEnumerable <TaxiNode> nodes, TaxiNode targetNode, XPlaneAircraftCategory targetCategory)
{
List <TaxiNode> untouchedNodes = nodes.ToList();
List <TaxiNode> touchedNodes = new List <TaxiNode>();
// Reset previously found paths
foreach (TaxiNode node in nodes)
{
node.DistanceToTarget = double.MaxValue;
node.NextNodeToTarget = null;
}
// Setup the targetnode
targetNode.DistanceToTarget = 0;
targetNode.NextNodeToTarget = null;
// Assign distances to all incoming edges of the target
foreach (TaxiEdge incoming in targetNode.IncomingEdges)
{
// Skip taxiways that are too small
if (targetCategory > incoming.MaxCategory)
{
continue;
}
// Mark the other side of the incoming edge as touched...
if (untouchedNodes.Contains(incoming.StartNode) && !touchedNodes.Contains(incoming.StartNode))
{
untouchedNodes.Remove(incoming.StartNode);
touchedNodes.Add(incoming.StartNode);
}
// And set the properties of the path
incoming.StartNode.DistanceToTarget = incoming.DistanceKM;
incoming.StartNode.NextNodeToTarget = targetNode;
incoming.StartNode.NameToTarget = incoming.LinkName;
incoming.StartNode.PathIsRunway = incoming.IsRunway;
incoming.StartNode.BearingToTarget = VortexMath.BearingRadians(incoming.StartNode, targetNode);
}
// Remove the target node completely, it's done.
untouchedNodes.Remove(targetNode);
// instantiate the comparer for taxinode list sorting
ShortestPathComparer spc = new ShortestPathComparer();
// Now rinse and repeat will we still have 'touched nodes' (unprocessed nodes with a path to the target)
while (touchedNodes.Count() > 0)
{
// Pick the next( touched but not finished) node to process, that is: the one which currently has the shortest path to the target
touchedNodes.Sort(spc);
TaxiNode currentNode = touchedNodes.First();
// And set the distances for the nodes with link towards the current node
foreach (TaxiEdge incoming in currentNode.IncomingEdges)
{
// Skip taxiways that are too small
if (targetCategory > incoming.MaxCategory)
{
continue;
}
// Avoid runways unless they are the only option.
double distanceToCurrent = incoming.DistanceKM;
if (incoming.IsRunway)
{
distanceToCurrent += 2.0;
}
// If the incoming link + the distance from the current node to the target is smaller
// than the so far shortest distance from the node on the otherside of the incoming link to
// the target... reroute the path from the otherside through the current node.
if ((distanceToCurrent + currentNode.DistanceToTarget) < incoming.StartNode.DistanceToTarget)
{
if (untouchedNodes.Contains(incoming.StartNode) && !touchedNodes.Contains(incoming.StartNode))
{
// The 'otherside' node is now ready to be processed
untouchedNodes.Remove(incoming.StartNode);
touchedNodes.Add(incoming.StartNode);
}
// Update the path properties
incoming.StartNode.DistanceToTarget = (currentNode.DistanceToTarget + distanceToCurrent);
incoming.StartNode.NextNodeToTarget = currentNode;
incoming.StartNode.NameToTarget = incoming.LinkName;
incoming.StartNode.PathIsRunway = incoming.IsRunway;
incoming.StartNode.BearingToTarget = incoming.Bearing;
}
}
// And the current is done.
touchedNodes.Remove(currentNode);
}
}