//this method performs the BFS search
public bool Search()
{
//create a std queue of edges
Queue <GraphEdge> queue = new Queue <GraphEdge>();
//create a dummy edge and put on the queue
GraphEdge dummy = new GraphEdge(source, source);
queue.Enqueue(dummy);
//mark the source node as visited
visited[source] = Visited;
//while there are edges in the queue keep searching
while (queue.Count != 0)
{
//remove the edge from the queue
GraphEdge next = queue.Dequeue();
//mark the parent of this node
route[next.To] = next.From;
//put it on the tree. (making sure the dummy edge is not placed on the tree)
if (next != dummy)
{
spanningTree.Add(next);
}
//exit if the target has been found
if (next.To == target)
{
return(true);
}
//push the edges leading from the node at the end of this edge
//onto the queue
foreach (GraphEdge edge in graph.edges[next.To])
{
//if the node hasn't already been visited we can push the
//edge onto the queue
if (visited[edge.To] == Unvisited)
{
queue.Enqueue(edge);
//and mark it visited
visited[edge.To] = Visited;
}
}
}
//no path to target
return(false);
}
//this method performs the DFS search
public bool Search()
{
//create a std stack of edges
Stack <GraphEdge> stack = new Stack <GraphEdge>();
//create a dummy edge and put on the stack
GraphEdge dummy = new GraphEdge(source, source);
stack.Push(dummy);
//while there are edges in the stack keep searching
while (stack.Count != 0)
{
//remove the edge from the stack
GraphEdge next = stack.Pop();
//make a note of the parent of the node this edge points to
route[next.To] = next.From;
//put it on the tree. (making sure the dummy edge is not placed on the tree)
if (next != dummy)
{
spanningTree.Add(next);
}
//and mark it visited
visited[next.To] = Visited;
//if the target has been found the method can return success
if (next.To == target)
{
return(true);
}
//push the edges leading from the node this edge points to onto
//the stack (provided the edge does not point to a previously
//visited node)
foreach (GraphEdge edge in graph.edges[next.To])
{
if (visited[edge.To] == Unvisited)
{
stack.Push(edge);
}
}
}
//no path to target
return(false);
}
//
// use to add he eight neighboring edges of a graph node that
// is positioned in a grid layout
public static void AddAllNeighboursToGridNode(NavGraph graph, int row, int col, int numCellsX, int numCellsY)
{
for (int i = -1; i <= +1; ++i)
{
for (int j = -1; j <= +1; ++j)
{
//skip if equal to this node
if (i == 0 && j == 0)
{
continue;
}
int nodeX = col + j;
int nodeY = row + i;
//check to see if this is a valid neighbour
if (ValidNeighbour(nodeX, nodeY, numCellsX, numCellsY))
{
//calculate the distance to this node
Vector2 posNode = graph.GetNode(row * numCellsX + col).Position;
Vector2 posNeighbour = graph.GetNode(nodeY * numCellsX + nodeX).Position;
float dist = Vector2.Length(posNeighbour - posNode);
GraphEdge newEdge;
newEdge = new GraphEdge(row * numCellsX + col, nodeY * numCellsX + nodeX, dist);
graph.AddEdge(newEdge);
//if graph is not a diagraph then an edge needs to be added going
//in the other direction
if (!graph.IsDigraph())
{
newEdge = new GraphEdge(nodeY * numCellsX + nodeX, row * numCellsX + col, dist);
graph.AddEdge(newEdge);
}
}
}
}
}