public static IList<Tile> CalculateAStarPath(Tile start, Tile goal, Level level, ActorBase actor)
{
if (start == null || goal == null)
return null;
if (goal.ActorInTile != null)
return null;
var path = new List<Tile>();
var nodes = new Node[level.Length,level.Width];
for (int x = 0; x < level.Length; x++)
{
for (int y = 0; y < level.Width; y++)
{
nodes[x, y] = new Node(x, y);
}
}
return CalculatePath(start, goal, level, nodes, actor);
}
private static IList<Tile> CalculatePath(Tile start, Tile goal, Level level, Node[,] nodes, ActorBase actor)
{
nodes[start.XCoord, start.YCoord].Cost = 0;
nodes[start.XCoord, start.YCoord].Depth = 0;
var open = new List<Node>();
var closed = new List<Node>();
var path = new List<Tile>();
int depth = 0;
open.Add(nodes[start.XCoord, start.YCoord]);
while (depth < MaximumSearchDistance && (open.Count != 0))
{
Node current = open[0];
if (current == nodes[goal.XCoord, goal.YCoord])
{
break;
}
open.RemoveAt(0);
closed.Add(current);
for (int x = -1; x <= 1; x++)
{
for (int y = -1; y <= 1; y++)
{
if (x == 0 && y == 0) continue;
if (x != 0 && y != 0) continue;
int candidateX = x + current.X;
int candidateY = y + current.Y;
if (CanMoveToTile(actor, level, start.XCoord, start.YCoord, current.X, current.Y, candidateX, candidateY))
{
float nextStepCost = current.Cost +
CalculateMovementCost(actor, level, current.X, current.Y, candidateX,
candidateY);
Node neighbor = nodes[candidateX, candidateY];
if (nextStepCost < neighbor.Cost)
{
if (open.Contains(neighbor))
{
open.Remove(neighbor);
}
if (closed.Contains(neighbor))
{
closed.Remove(neighbor);
}
}
if (!open.Contains(neighbor) && !closed.Contains(neighbor))
{
neighbor.Cost = nextStepCost;
neighbor.Heuristic = GetHeuristicCost(actor, level.GetTileAt(candidateX, candidateY),
goal);
depth = Math.Max(depth, neighbor.SetParent(current));
open.Add(neighbor);
open = open.OrderBy(o => o.TotalCost()).ToList();
}
}
}
}
}
if (nodes[goal.XCoord, goal.YCoord].Parent == null) return null;
Node target = nodes[goal.XCoord, goal.YCoord];
while (target != nodes[start.XCoord, start.YCoord])
{
path.Insert(0, level.GetTileAt(target.X, target.Y));
target = target.Parent;
}
path.Insert(0, start);
if (path.Count > actor.CurrentStats.MovementRange + 1) return null;
return path;
}
public int SetParent(Node parent)
{
Depth = parent.Depth + 1;
Parent = parent;
return Depth;
}
