public static IEnumerable <HexCoords> AStar(this MapUnit unit, HexCoords dst)
{
Dictionary <HexCoords, PathNode> result = new Dictionary <HexCoords, PathNode>();
PriorityQueue <PathNode> frontier = new PriorityQueue <PathNode>();
frontier.Enqueue(new PathNode(
0,
unit.Heuristic(unit.loc, dst),
null,
unit.loc));
while (frontier.Count > 0)
{
PathNode current = frontier.Dequeue();
// If we've arrived
if (current.loc == dst)
{
return(current.pathTo);
}
// If we already have a path to this location that's at least this cheap,
// don't repeat it
if (!result.IsRedundant(current))
{
// If we can stay in the current location, mark it down as a destination
if (unit.CanStay(current.loc))
{
result[current.loc] = current;
}
// If we can leave the current location, try entering neighboring locations
int movesRemaining = (int)unit.moveRange - current.costToNode;
if ((movesRemaining > 0) && unit.CanLeave(current.loc))
{
// If we can enter any neighboring locations, try to do so later.
IEnumerable <MapCell> neighborCells = current.loc.neighbors
.Where(map.InBounds)
.Select(map.CellAt)
.Where(unit.CanEnter);
foreach (MapCell neighbor in neighborCells)
{
frontier.Enqueue(new PathNode(
current.costToNode + 1,
current,
neighbor.loc));
}
}
}
}
return(null);
}
public static bool CanStay(
this MapUnit unit,
HexCoords loc)
{
if (!map.InBounds(loc))
{
return(false);
}
else
{
return(unit.CanStay(map[loc]));
}
}