private static List <GridSquare> GetNeighbours(GridSquare from, char[,] maze, int targetx, int targety)
{
List <GridSquare> result = new List <GridSquare>();
if (from.Y - 1 >= 0 && maze[from.Y - 1, from.X] == '.')
{
GridSquare neighbour = new GridSquare(from.X, from.Y - 1, true);
neighbour.Score = Math.Abs((from.X - targetx) + (from.Y - targety - 1));
neighbour.Parent = from;
result.Add(neighbour);
}
if (from.Y + 1 < maze.GetLength(0) && maze[from.Y + 1, from.X] == '.')
{
GridSquare neighbour = new GridSquare(from.X, from.Y + 1, true);
neighbour.Score = Math.Abs((from.X - targetx) + (from.Y - targety + 1));
neighbour.Parent = from;
result.Add(neighbour);
}
if (from.X - 1 >= 0 && maze[from.Y, from.X - 1] == '.')
{
GridSquare neighbour = new GridSquare(from.X - 1, from.Y, true);
neighbour.Score = Math.Abs((from.X - 1 - targetx) + (from.Y - targety));
neighbour.Parent = from;
result.Add(neighbour);
}
if (from.X + 1 < maze.GetLength(1) && maze[from.Y, from.X + 1] == '.')
{
GridSquare neighbour = new GridSquare(from.X + 1, from.Y, true);
neighbour.Score = Math.Abs((from.X + 1 - targetx) + (from.Y - targety));
neighbour.Parent = from;
result.Add(neighbour);
}
return(result);
}
public static int AStarPathFind(int fromX, int fromY, int targetX, int targetY, char[,] maze)
{
List <GridSquare> open_list = new List <GridSquare>();
List <GridSquare> closed_list = new List <GridSquare>();
open_list.Add(new GridSquare(fromX, fromY, true));
bool bTargetReachable = false;
while (open_list.Count > 0)
{
GridSquare square = open_list.OrderBy(sq => sq.Score).First();
closed_list.Add(square);
if (closed_list.Exists(sq => sq.X == targetX && sq.Y == targetY))
{
bTargetReachable = true;
break;
}
List <GridSquare> neighbours = GetNeighbours(square, maze, targetX, targetY);
for (int i = 0; i < neighbours.Count; i++)
{
//In closed list? ignore!
if (closed_list.Exists(sq => sq.X == neighbours[i].X && sq.Y == neighbours[i].Y))
{
continue;
}
//In open list?
if (open_list.Exists(sq => sq.X == neighbours[i].X && sq.Y == neighbours[i].Y))
{
GridSquare update = open_list.Find(sq => sq.X == neighbours[i].X && sq.Y == neighbours[i].Y);
if (neighbours[i].Score < update.Score)
{
update.Score = neighbours[i].Score;
}
}
else
{
open_list.Add(neighbours[i]);
}
}
open_list.Remove(square);
}
int steps = 0;
if (bTargetReachable)
{
GridSquare target = closed_list.First(sq => sq.X == targetX && sq.Y == targetY);
while (target.Parent != null)
{
//maze[target.Y, target.X] = 'O';
target = target.Parent;
steps++;
}
}
return(steps);
}
public GridSquare(int x, int y, bool walkable)
{
X = x;
Y = y;
Walkable = walkable;
Parent = null;
Score = 0;
}