/// <summary>
/// Calculate distance between two nodes to be used as edge weidght
/// </summary>
/// <param name="start">First node</param>
/// <param name="end">Second node</param>
/// <returns>Distance between the two nodes</returns>
private Double GetEdgeWeight(Node start, Node end)
{
System.Diagnostics.Debug.WriteLine(start.ID + end.ID);
Double DX = start.Coordinates.X - end.Coordinates.X;
Double DY = start.Coordinates.Y - end.Coordinates.Y;
Double DD = Math.Sqrt((DX * DX) + (DY * DY));
return DD;
}
/// <summary>
/// Finds the shortes route between the two specified nodes. If the disabled
/// parameter is set to true, nodes marked as not disabled-friendly will not
/// be considered at all. If there is no route between the two nodes (should
/// not happen in the final version of the program) the route will only consist
/// of the endpoint.
/// </summary>
/// <param name="start">Node to start from</param>
/// <param name="end">Node to arrive to</param>
/// <param name="disabled">Whether to find a disabled-friendly route</param>
/// <returns>
/// A list of Nodes that create the path between the two points specified,
/// including those two points
/// </returns>
public List<Node> FindRoute(Node start, Node end, bool disabled)
{
Dictionary<Node, double> distances = new Dictionary<Node, double>();
Dictionary<Node, Node> predecessors = new Dictionary<Node, Node>();
/* Initializing both lists */
foreach (Node node in NodeList)
{
distances.Add(node, double.MaxValue);
predecessors.Add(node, null);
}
distances[start] = 0.0;
/* Initializing the list we will be deleting nodes from */
List<Node> nodes = new List<Node>(NodeList);
while (nodes.Count > 0)
{
double smallestDist = double.MaxValue;
Node nearestNode = null;
foreach(Node n in nodes)
if (distances[n] < smallestDist)
{
smallestDist = distances[n];
nearestNode = n;
}
if (smallestDist == double.MaxValue) break;
nodes.Remove(nearestNode);
if (nearestNode.Equals(end)) break;
foreach (Node n in GetNeighbours(nearestNode, disabled))
{
double d = distances[nearestNode] + GetEdgeWeight(nearestNode, n);
if (d < distances[n])
{
distances[n] = d;
predecessors[n] = nearestNode;
}
}
}
/* Creating the route */
List<Node> route = new List<Node>();
Node u = end;
while (predecessors[u] != null)
{
route.Add(predecessors[u]);
u = predecessors[u];
}
route.Reverse();
route.Add(end);
return route;
}
public Edge(Node NodeStart, Node NodeEnd, double Weight)
{
this.NodeStart = NodeStart;
this.NodeEnd = NodeEnd;
this.Weight = Weight;
}
/// <summary>
/// Finds all neighbours of the specified node. If the disabled parametet is
/// set to true, only disabled-friendly nodes will be returned.
/// </summary>
/// <param name="source">Node to analyze</param>
/// <param name="disabled">Whether to return only disabled-friendly nodes</param>
/// <returns>A list of nodes directly connected to the node specified</returns>
private List<Node> GetNeighbours(Node source, bool disabled)
{
List<Node> neighbours = new List<Node>();
foreach (Edge edge in EdgeList)
{
if (edge.NodeStart.Equals(source) && (!disabled || edge.NodeEnd.Disabled))
neighbours.Add(edge.NodeEnd);
if (edge.NodeEnd.Equals(source) && (!disabled || edge.NodeStart.Disabled))
neighbours.Add(edge.NodeStart);
}
return neighbours;
}
/// <summary>
/// Find the edge connecting the two specified nodes and returns its weight.
/// </summary>
/// <param name="start">One of the nodes</param>
/// <param name="end">The other node</param>
/// <returns>Weight of the edge between the two nodes, or double.MaxValue if there is no edge</returns>
private double GetEdgeWeight(Node start, Node end)
{
foreach (Edge edge in EdgeList)
{
if (edge.NodeStart.Equals(start) && edge.NodeEnd.Equals(end)) return edge.Weight;
if (edge.NodeStart.Equals(end) && edge.NodeEnd.Equals(start)) return edge.Weight;
}
return double.MaxValue;
}
