/// <summary>
/// This method returns a double representing the length of time (in seconds) that it would
/// take to get to from a PseudoNode to a Node along the same Path. If the given Node is
/// not on the same Path, this returns Double.MAX_VALUE as this method contains no support
/// for routing.
/// </summary>
/// <param name="node"></param>
/// <param name="pseudoNode"></param>
/// <returns></returns>
public double GetTimeToNodeFrom(Node node, PseudoNode pseudoNode)
{
if (pseudoNode.GetPath() == this)
{
return(GetTimeToNodeFrom(node, pseudoNode.GetDistanceAlongPath()));
}
else
{
Debug.WriteLine("The PseudoNode does not lie on this Path.");
return(Double.MaxValue);
}
}
/// <summary>
/// This method returns a double that represents the length of time (in seconds) that it
/// would take to get from one PseudoNode on the Path to another on the Path. If one of
/// the nodes is not on this Path, this method will return Double.MaxValue.
/// </summary>
/// <param name="destination_node"></param>
/// <param name="source_node"></param>
/// <returns></returns>
public double GetTimeToPseudoNodeFrom(PseudoNode destination_node, PseudoNode source_node)
{
// Check both PseudoNodes are on the Path
if (destination_node.GetPath() != this || source_node.GetPath() != this)
{
return(Double.MaxValue);
}
// Calculate length of time
double destination_distance = destination_node.GetDistanceAlongPath();
double source_distance = source_node.GetDistanceAlongPath();
double time = (destination_distance - source_distance) / speed_limit;
time = (time > 0) ? time : -time;
return(time);
}
/// <summary>
/// Sets up a PseudoNode at the same point as the given PseudoNode.
/// </summary>
/// <param name="node"></param>
public PseudoNode(PseudoNode node)
{
path = node.GetPath();
distance_along_path = node.GetDistanceAlongPath();
}
/// <summary>
/// Initialises a Route by giving a start and end PseudoNode, and calculates the quickest Route between them.
/// </summary>
/// <param name="_source_node"></param>
/// <param name="_end_node"></param>
public Route(PseudoNode _source_node, PseudoNode _end_node)
{
// Storing the source and destination nodes
source_node = new PseudoNode(_source_node);
end_node = new PseudoNode(_end_node);
Node [] source_nodes = source_node.GetPath().GetNodes();
Node [] end_nodes = end_node.GetPath().GetNodes();
bool [] end_nodes_mapped = { false, false };
List <NodeAndTime> nodes_and_times = new List <NodeAndTime>();
List <Node> nodes = Map.GetNodes();
// Setting the initial times to get to each node from the source node
foreach (Node node in nodes)
{
if (node == source_nodes[0] || node == source_nodes[1])
{
nodes_and_times.Add(new NodeAndTime(node, source_node.GetPath().GetTimeToNodeFrom(node, source_node)));
}
else
{
nodes_and_times.Add(new NodeAndTime(node, false));
}
}
// Implementing Dijkstra's algorithm:
bool complete = false;
while (!complete)
{
// Sort to ensure that the nearest (by time) nodes to the source node are at the top of the List
Sort(nodes_and_times);
// Finding the next node that has not been mapped
NodeAndTime analysis_node = null;
foreach (NodeAndTime node_and_time in nodes_and_times)
{
if (!node_and_time.AdjacentNodesMapped())
{
analysis_node = node_and_time;
break;
}
}
// If all nodes have been mapped, then the analysis_node was not set in the previous code snippet.
// Hence we need not run the rest of the loop and we can finish the while loop. This is a fail safe
// to ensure that the code does not crash. In ordinary circumstances, this scenario should be
// handled below, at the bottom of the while loop.
if (analysis_node == null)
{
complete = true;
continue;
}
// Get adjacent nodes
List <Node> adj_nodes_temp = Map.GetNodesAdjacentToNode(analysis_node.GetNode());
foreach (Node node in adj_nodes_temp)
{
// Calculate time coming from this node
double new_time = Map.GetPathWithNodes(analysis_node.GetNode(), node).GetTime() + analysis_node.GetTime();
// If the time lower than it would be taking the previous route here, change that NodeAndTime object to come through this way instead
NodeAndTime previous_node_and_time = GetNodeAndTime(node, nodes_and_times);
if (new_time < previous_node_and_time.GetTime())
{
List <NodeAndTime> new_shortest_route = new List <NodeAndTime>(analysis_node.GetShortestRouteToNodeForCalc());
new_shortest_route.Add(analysis_node);
previous_node_and_time.SetShortestRouteToNode(new_shortest_route);
previous_node_and_time.SetTime(new_time);
}
}
analysis_node.SetAdjacentNodesMapped(true);
// Check if both Nodes either side of the PseudoNode have been analysed.
if (analysis_node.GetNode() == end_nodes[0])
{
end_nodes_mapped[0] = true;
}
else if (analysis_node.GetNode() == end_nodes[1])
{
end_nodes_mapped[1] = true;
}
// Completing the loop if both of the end Nodes have been mapped
if (end_nodes_mapped[0] && end_nodes_mapped[1])
{
complete = true;
}
}
// Getting the time that it will take to get to the PseudoNode via both Nodes either side of the containing Route
NodeAndTime [] end_node_and_times = { GetNodeAndTime(end_nodes[0], nodes_and_times), GetNodeAndTime(end_nodes[1], nodes_and_times) };
double time_from_end_node_1 = end_node_and_times[0].GetTime() + end_node.GetPath().GetTimeToNodeFrom(end_node_and_times[0].GetNode(), end_node);
double time_from_end_node_2 = end_node_and_times[1].GetTime() + end_node.GetPath().GetTimeToNodeFrom(end_node_and_times[1].GetNode(), end_node);
// Selecting to go through the Node that will give the shortest time, and converting these to a list of Nodes.
if (time_from_end_node_1 <= time_from_end_node_2)
{
node_route = end_node_and_times[0].ConvertToListOfNodes();
path_route = end_node_and_times[0].ConvertToListOfPaths();
}
else
{
node_route = end_node_and_times[1].ConvertToListOfNodes();
path_route = end_node_and_times[1].ConvertToListOfPaths();
}
// Adding start and end Paths on as they may not currently be there
if (path_route.Count == 0)
{
path_route.Add(source_node.GetPath());
}
if (path_route[0] != source_node.GetPath())
{
path_route.Insert(0, source_node.GetPath());
}
if (path_route[path_route.Count - 1] != end_node.GetPath())
{
path_route.Add(end_node.GetPath());
}
// Determine which directions the Paths should be travelled in
DetermineDirections();
}
/// <summary>
/// This method returns a Direction that specifies whether the Path that the PseudoNode is on should be travelled
/// forwards or backwards (i.e. from Path.GetNodes()[0] to Path.GetNodes()[1] or vice versa). If the PseudoNode
/// does not sit on a Path in this Route, this method will return Direction.FORWARDS.
/// </summary>
/// <param name="pseudo_node"></param>
/// <returns></returns>
public Direction GetDirection(PseudoNode pseudo_node)
{
return(GetDirection(pseudo_node.GetPath()));
}
/// <summary>
/// This method finds the next Path on the Route by the current position of the PseudoNode. If the PseudoNode is
/// not on the Route, or if it lies on the last Path in the Route, this method will return null.
/// </summary>
/// <param name="current_position"></param>
/// <returns></returns>
public Path GetNextPath(PseudoNode current_position)
{
return(GetNextPath(current_position.GetPath()));
}
/// <summary>
/// Returns the Path that the user is currently on.
/// </summary>
/// <returns></returns>
public Path GetCurrentPath()
{
return(position.GetPath());
}
