/// <summary>
/// Finds the shortest path from the start to the end position.
/// </summary>
/// <param name="beginPosition">The (x, y) pair that represents the start location.</param>
/// <param name="endPosition">The (x, y) pair that represents the end location.</param>
/// <returns>A list of mapNodes representing the shortest path from start to end.</returns>
public static List <MapNode> getShortestPathTo(Vector2 beginPosition, Vector2 endPosition)
{
MapNode start = getNearestNodeTo(beginPosition.X, beginPosition.Y, entryPoint), goal = getNearestNodeTo(endPosition.X, endPosition.Y, entryPoint);
List <AStarElement> pQueue = new List <AStarElement>(); //priority queue
pQueue.Add(new AStarElement(start, goal));
AStarElement toAdd = null;
while (!pQueue[0].isFullPath())
{
//The shortest path found so far will always be at the head of the list,
//so per aStar, build on that path.
AStarElement best = pQueue[0];
foreach (MapNode n in best.getLastNode().getAllNodes())
{
if (best.exists(n))
{
continue;
}
toAdd = new AStarElement(best);
toAdd.addNode(n);
pQueue.Add(toAdd);
if (n == goal)
{
break;
}
}
if (!best.isFullPath())
{
pQueue.Remove(best);
}
pQueue.Sort(); //Custom sorting that makes shortest path be sorted to head of list.
} //while
return(pQueue[0].getNodes());
}
/// <summary>
/// Creates a new path using an existing AStar path.
/// </summary>
/// <param name="obj">The AStarElement from which to build this element.</param>
public AStarElement(AStarElement obj)
{
chain = new List <MapNode>();
foreach (MapNode n in obj.chain)
{
chain.Add(n);
}
target = obj.target;
}
public int CompareTo(object obj)
{
AStarElement o = (AStarElement)obj;
if (f == o.f)
{
return(h() - o.h());
}
return(f - o.f);
}
