internal void FillLandmark(IBoard <IHex> board)
{
if (board != null)
{
backingStore = new BoardStorage <short> .BlockedBoardStorage32x32(board.MapSizeHexes, c => - 1);
var start = board[Coords];
var queue = DictionaryPriorityQueue <int, IHex> .NewQueue();
TraceFlags.FindPathDetail.Trace(true, "Find distances from {0}", start.Coords);
queue.Enqueue(0, start);
HexKeyValuePair <int, IHex> item;
while (queue.TryDequeue(out item))
{
var here = item.Value;
var key = item.Key;
if (backingStore[here.Coords] > 0)
{
continue;
}
TraceFlags.FindPathDetail.Trace("Dequeue Path at {0} w/ cost={1,4}.", here, key);
backingStore[here.Coords] = (short)key;
foreach (var there in here.GetAllNeighbours().Where(n => n != null && n.Hex.IsOnboard()))
{
var cost = board.DirectedStepCost(here, there.HexsideEntry);
if (cost > 0 && backingStore[there.Hex.Coords] == -1)
{
TraceFlags.FindPathDetail.Trace(" Enqueue {0}: {1,4}", there.Hex.Coords, cost);
queue.Enqueue(key + cost, there.Hex);
}
}
}
}
}
/// <summary>Returns an <c>IPath</c> for the optimal path from coordinates <c>start</c> to <c>goal</c>.</summary>
/// <param name="start">Coordinates for the <c>last</c> step on the desired path.</param>
/// <param name="goal">Coordinates for the <c>first</c> step on the desired path.</param>
/// <param name="stepCost">Cost to extend path by hex at <c>coords</c> from hex at direction <c>hexside</c>.</param>
/// <param name="heuristic">Returns a cost estimate from a range value.</param>
/// <param name="isOnboard">Returns whether the coordinates specified are "on board".</param>
public static IPath FindPath(
HexCoords start,
HexCoords goal,
Func <HexCoords, Hexside, int> stepCost,
Func <int, int> heuristic,
Func <HexCoords, bool> isOnboard
)
{
if (stepCost == null)
{
throw new ArgumentNullException("stepCost");
}
if (heuristic == null)
{
throw new ArgumentNullException("heuristic");
}
if (isOnboard == null)
{
throw new ArgumentNullException("isOnboard");
}
var vectorGoal = goal.Canon - start.Canon;
var closed = new HashSet <HexCoords>();
var open = new HashSet <HexCoords>();
var queue = DictionaryPriorityQueue <int, Path> .NewQueue();
TraceFlags.FindPathDetail.Trace(true, "Find path from {0} to {1}; vectorGoal = {0}",
start.Canon, goal.Canon, vectorGoal);
queue.Enqueue(0, new Path(start));
HexKeyValuePair <int, Path> item;
while (queue.TryDequeue(out item))
{
var path = item.Value;
if (closed.Contains(path.StepCoords))
{
continue;
}
open.Add(item.Value.StepCoords);
TraceFlags.FindPathDetail.Trace(
"Dequeue Path at {0} w/ cost={1,4} at {2}; estimate={3,4}:{4,4}.",
item.Value.StepCoords, item.Value.TotalCost, item.Value.HexsideExit,
item.Key >> 16, item.Key & 0xFFFF);
if (path.StepCoords.Equals(goal))
{
return(path);
}
closed.Add(path.StepCoords);
foreach (var neighbour in path.StepCoords.GetNeighbours()
.Where(n => isOnboard(n.Coords))
)
{
var cost = stepCost(path.StepCoords, neighbour.Hexside);
if (cost > 0)
{
var newPath = path.AddStep(neighbour, (ushort)cost);
var estimate = Estimate(heuristic, vectorGoal, goal, newPath.StepCoords, newPath.TotalCost);
TraceFlags.FindPathDetail.Trace(" Enqueue {0}: {1,4}:{2,3}",
neighbour.Coords, estimate >> 16, estimate & 0xFFFF);
queue.Enqueue(estimate, newPath);
}
}
}
return(null);
}
