/// <summary>
/// A* pathfinding algorithm.
/// </summary>
/// <param name="request">PathRequest object.</param>
/// <param name="callback">Callback object.</param>
public void FindPath(PathRequest request, Action <PathResult> callback)
{
Stopwatch sw = new Stopwatch();
sw.Start();
List <Node> waypoints = new List <Node>();
bool pathSuccess = false;
Node startNode = _aGrid.getNode(request.pathStart);
Node targetNode = _aGrid.getNode(request.pathEnd);
startNode.parent = startNode;
if (targetNode.GetState() == Enums.TileState.FREE)
{
Heap <Node> openSet = new Heap <Node>(_aGrid.MaxSize);
HashSet <Node> closedSet = new HashSet <Node>();
openSet.Add(startNode);
while (openSet.Count > 0)
{
Node currentNode = openSet.RemoveFirst();
closedSet.Add(currentNode);
if (currentNode == targetNode)
{
sw.Stop();
//print ("Path found: " + sw.ElapsedMilliseconds + " ms");
pathSuccess = true;
break;
}
foreach (Node neighbour in _aGrid.GetNeighbours(currentNode))
{
if (neighbour.GetState() != Enums.TileState.FREE || closedSet.Contains(neighbour))
{
continue;
}
int newMovementCostToNeighbour =
currentNode.gCost + GetDistance(currentNode, neighbour) + neighbour.movementPenalty;
if (newMovementCostToNeighbour < neighbour.gCost || !openSet.Contains(neighbour))
{
neighbour.gCost = newMovementCostToNeighbour;
neighbour.hCost = GetDistance(neighbour, targetNode);
neighbour.parent = currentNode;
if (!openSet.Contains(neighbour))
{
openSet.Add(neighbour);
}
else
{
openSet.UpdateItem(neighbour);
}
}
}
}
}
if (pathSuccess)
{
waypoints = RetracePath(startNode, targetNode);
pathSuccess = waypoints.Count > 0;
}
callback(new PathResult(waypoints, pathSuccess, request.parameter, request.callback));
}