/// <summary>
/// Calculates the shortest path between the airplane and the point through which it has to leave the airspace.
/// </summary>
/// <param name="points">All the checkpoints in the airspace. No airstrips, no airplanes.</param>
/// <param name="exitCheckpoint">The checkpoint through which the plane has to leave the airspace.</param>
public void CalculateShortestPathLeavingAirspace(List <Checkpoint> points)
{
this.ReachableNodes.Clear();
this.ShortestPath.Clear();
foreach (Checkpoint point in points)
{
if (target == null && point.ParentCellType == CellType.FINAL)
{
this.AddSingleDestination(point, CalculateTimeBetweenPoints(point));
}
else if (target != null && target.Equals(ShortestPath.Last)
) //if this doesn't work: ((Checkpoint)target.Value).ParentCellType == Cell.BORDER
{
ShortestPath.Clear();
ShortestPath.AddFirst(target);
return;
}
else if (target != null && point.ParentCellType == ((Checkpoint)target.Value).ParentCellType)
{
this.AddSingleDestination(point, CalculateTimeBetweenPoints(point));
}
point.ShortestPath.Clear();
point.DistanceFromSource = int.MaxValue;
}
exitDestination.DistanceFromSource = int.MaxValue;
exitDestination.ShortestPath.Clear();
HashSet <AbstractCheckpoint> settledCheckpoints = new HashSet <AbstractCheckpoint>();
HashSet <AbstractCheckpoint> unsettledCheckpoints = new HashSet <AbstractCheckpoint> {
this
};
while (unsettledCheckpoints.Count != 0)
{
AbstractCheckpoint currentCheckpnt = this.GetLowestDistanceNode(unsettledCheckpoints);
unsettledCheckpoints.Remove(currentCheckpnt);
foreach (var pair in currentCheckpnt.ReachableNodes)
{
AbstractCheckpoint reachableCheckpoint = pair.Key;
double edgeWeight = pair.Value;
if (!settledCheckpoints.Contains(reachableCheckpoint))
{
var shortestPath = CalculateMinDistance(reachableCheckpoint, edgeWeight, currentCheckpnt);
if (shortestPath != null && reachableCheckpoint.GetType() == typeof(Checkpoint) &&
((Checkpoint)reachableCheckpoint).ParentCellType == CellType.BORDER)
{
shortestPath.AddLast(reachableCheckpoint);
this.ShortestPath = new LinkedList <AbstractCheckpoint>();
var pathNode = shortestPath.First;
while (pathNode != null)
{
this.ShortestPath.AddLast(pathNode.Value);
pathNode = pathNode.Next;
}
}
unsettledCheckpoints.Add(reachableCheckpoint);
}
}
settledCheckpoints.Add(currentCheckpnt);
}
if (this.ShortestPath.Count != 0)
{
movingDirectionHasChanged = true;
target = ShortestPath.First;
target = target.Next;
}
}
/// <summary>
/// Uses Pythagoras' theorem to calculate the distance between two checkpoints.
/// </summary>
/// <param name="a">The checkpoint we are looking for the distance from.</param>
/// <returns>The distance between the two checkpoints given as arguments.</returns>
public virtual double CalculateDistanceBetweenPoints(AbstractCheckpoint a)
{
return(Math.Sqrt(Math.Pow(Math.Abs(this.CoordinateX - a.CoordinateX), 2) +
Math.Pow(Math.Abs(this.CoordinateY - a.CoordinateY), 2)));
}
/// <summary>
/// Calculates the shortest path between the airplane and its final destination - the airstrip.
/// </summary>
/// <param name="points">All the checkpoints in the airspace. No airstrips, no airplanes.</param>
/// <param name="landingStrip">The landing strip the airplane is going for.</param>
public void CalculateShortestPathToAirstrip(List <Checkpoint> points, Airstrip landingStrip)
{
this.ReachableNodes.Clear();
this.ShortestPath.Clear();
foreach (Checkpoint point in points)
{
if (target == null && (point.ParentCellType == CellType.UPPER ||
point.ParentCellType == CellType.UNASSIGNED))
{
this.AddSingleDestination(point, CalculateTimeBetweenPoints(point));
}
else if (target != null && target.Value.GetType() == typeof(Airstrip))
{
ShortestPath.Clear();
ShortestPath.AddFirst(target);
return;
}
else if (target != null && point.ParentCellType == ((Checkpoint)target.Value).ParentCellType)
{
this.AddSingleDestination(point, CalculateTimeBetweenPoints(point));
}
point.ShortestPath.Clear();
point.DistanceFromSource = int.MaxValue;
}
landingStrip.DistanceFromSource = int.MaxValue;
landingStrip.ShortestPath.Clear();
HashSet <AbstractCheckpoint> settledCheckpoints = new HashSet <AbstractCheckpoint>();
HashSet <AbstractCheckpoint> unsettledCheckpoints = new HashSet <AbstractCheckpoint> {
this
};
while (unsettledCheckpoints.Count != 0)
{
AbstractCheckpoint currentCheckpnt = this.GetLowestDistanceNode(unsettledCheckpoints);
unsettledCheckpoints.Remove(currentCheckpnt);
foreach (var pair in currentCheckpnt.ReachableNodes)
{
AbstractCheckpoint reachableCheckpoint = pair.Key;
double edgeWeight = pair.Value;
if (!settledCheckpoints.Contains(reachableCheckpoint))
{
var shortestPath = CalculateMinDistance(reachableCheckpoint, edgeWeight, currentCheckpnt);
if (shortestPath != null && reachableCheckpoint.GetType() == typeof(Airstrip))
{
shortestPath.AddLast(reachableCheckpoint);
this.ShortestPath = new LinkedList <AbstractCheckpoint>();
var pathNode = shortestPath.First;
while (pathNode != null)
{
this.ShortestPath.AddLast(pathNode.Value);
pathNode = pathNode.Next;
}
}
unsettledCheckpoints.Add(reachableCheckpoint);
}
}
settledCheckpoints.Add(currentCheckpnt);
}
if (this.ShortestPath.Count != 0)
{
movingDirectionHasChanged = true;
target = ShortestPath.First;
target = target.Next;
}
}
/// <summary>
/// Using just the distance as a factor for the shortest distance calculation seems silly.
/// This is why this method calculates the time it will take an <see cref="Airplane"/>
/// to get from the current point to a.
/// </summary>
/// <param name="a">The point, to which the time needed to get to it needs to be calculated. </param>
/// <returns></returns>
public virtual double CalculateTimeBetweenPoints(AbstractCheckpoint a)
{
return(CalculateDistanceBetweenPoints(a) / this.MaxSpeed);
}
