public ANode(int g = 0, int h = 0, Vector2?position = null, ANode parent = null)
{
G = g;
H = h;
Position = position != null ? (Vector2)position : new Vector2(-1, -1);
Parent = parent;
}
public override bool Equals(object obj)
{
if (obj == null)
{
return(false);
}
if (!(obj is ANode))
{
return(false);
}
ANode n = (ANode)obj;
return(Position.Equals(n.Position));
}
public Path ComputePath(Vector2 start, Vector2 end)
{
if (Path == null)
{
throw new InvalidOperationException();
}
if (/*start.Equals(Path.Origin) && */ end.Equals(Path.Goal))
{
return(Path);
}
if (start == null || end == null)
{
throw new ArgumentNullException();
}
if (start.X < 0 || start.X >= Map.Width || start.Y < 0 || start.Y >= Map.Height ||
end.X < 0 || end.X >= Map.Width || end.Y < 0 || end.Y >= Map.Height)
{
throw new ArgumentException();
}
Open = new List <ANode>(1);
Closed = new List <ANode>();
Path = new Path();
// Add the starting point to the path
Path.Add(start);
// Add the starting point to the Open nodes
Open.Add(new ANode(0, ManhattanDistance(start, end), start));
Dictionary <Vector2, Vector2> map = new Dictionary <Vector2, Vector2>();
// While Open is not empty
int rec = 0;
while (Open.Count > 0)
{
int q_index = minF(Open);
// q is the node which has the minimum F in the Open nodes. This is THIS node which will be evaluated in this iteration.
ANode q = Open[q_index];
if (q.Position.Equals(end))
{
/*if (!Path.Contains(q.Position))
* Path.Add(q.Position);*/
return(ReconstructPath(map, q.Position));
}
// Remove q from the Open nodes
Open.Remove(q);
Closed.Add(q);
// Generate q's 4 successors (neighbors)
List <ANode> successors = new List <ANode>(4);
//successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X - 1, q.Position.Y - 1), q));
successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X, q.Position.Y - 1), q));
//successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X + 1, q.Position.Y - 1), q));
successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X + 1, q.Position.Y), q));
//successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X + 1, q.Position.Y + 1), q));
successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X, q.Position.Y + 1), q));
//successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X - 1, q.Position.Y + 1), q));
successors.Add(new ANode(ANode.INFINITY, 0, new Vector2(q.Position.X - 1, q.Position.Y), q));
// TODO: Merge the two for-loop in one, and replace the Remove and i-- by 'continue'
// Check if all successors are correct
/*
* for (int i = 0; i < successors.Count; i++)
* {
* Vector2 p = successors[i].Position;
*
* // If the node is in Closed, then the node is already evaluated
* /*if (Closed.Contains(successors[i]))
* {
* successors.RemoveAt(i);
* i--;
* }
*
* if (i < 0)
* i = 0;*
*
* // Check if position is correct
* if ((p.X < 0 || p.X >= Map.Width || p.Y < 0 || p.Y >= Map.Height ||
* p.X < 0 || p.X >= Map.Width || p.Y < 0 || p.Y >= Map.Height) && i <= successors.Count - 1)
* {
* successors.RemoveAt(i);
* i--;
* }
*
* if (i < 0)
* i = 0;
*
* // Check if the node in the maze is not a block
* if (Cell.IsTileTypeBlock(Map[p].Tile) && i <= successors.Count - 1)
* {
* successors.RemoveAt(i);
* i--;
* }
*
* if (i < 0)
* i = 0;
*
* // Finally, after all those checks, add the successor in Open:
* /*if (i <= successors.Count - 1 && !Open.Contains(successors[i]))
* Open.Add(successors[i]);*
* }*/
// Now that successors contains valid nodes, continue the A* algorithm
// For each succesor 's', update its variables G and H
ANode s = null;
for (int i = 0; i < successors.Count; i++)
{
s = successors[i];
Vector2 p = s.Position;
// Check if position is correct
if (p.X < 0 || p.X >= Map.Width || p.Y < 0 || p.Y >= Map.Height)
{
continue;
}
if (Cell.IsTileTypeBlock(Map[p].Tile))
{
continue;
}
/*if (s.Equals(end))
* break;*/
/* mit.edu solution : */
/*
* // distance between s and q
* s.G = q.G + ManhattanDistance(s.Position, q.Position);
*
* // distance between goal and s
* s.H = ManhattanDistance(end, s.Position);
*
* // s.F is automatically calculated (see ANode.G and ANode.H properties for more details)
* List<ANode> openUclosed = new List<ANode>(Open.Count + Closed.Count);
* openUclosed.AddRange(Open);
* openUclosed.AddRange(Closed);
* foreach (ANode n in openUclosed)
* if (s.Position.Equals(n.Position) && n.F < s.F)
* continue;
*/
/* Wikipedia solution: */
if (Closed.Contains(s))
{
continue;
}
if (!Open.Contains(s))
{
Open.Add(s);
}
// distance between s and q
int tentative_g = q.G + ManhattanDistance(s.Position, q.Position);
if (tentative_g >= s.G)
{
continue;
}
if (!Path.Contains(q.Position))
{
Path.Add(s.Position);
}
map[s.Position] = q.Position;
s.G = tentative_g;
// distance between goal and s
s.H = ManhattanDistance(end, s.Position);
}
// q is now evaluated, it can be stored in Closed
//Closed.Add(q);
rec++;
if (rec >= 100)
{
throw new InfiniteLoopException();
}
}
return(Path);
}
