int CalculateDistances(Vector2Int dest, BFSTreeNode node)
{
if (node.isDest)
{
return(1);
}
if (node.children.Count == 0)
{
return(-1);
}
// assign distance values for all children
int minDistance = 1000000000;
foreach (BFSTreeNode child in node.children)
{
int distance = CalculateDistances(dest, child);
if (distance == -1)
{
node.distances.Add(-1);
}
else
{
node.distances.Add(distance);
if (distance < minDistance)
{
minDistance = distance;
}
}
}
// return minimum, non-zero distance value
return(1 + minDistance);
}
void GenerateTree(Vector2Int start, Vector2Int dest, MapHandler mapHnd)
{
root = new BFSTreeNode(start);
// Track all cells we have or might visit
Dictionary <Vector2Int, bool> blacklisted = new Dictionary <Vector2Int, bool> ();
// structure to keep track of frontier of breadth-first search
Queue <BFSTreeNode> frontier = new Queue <BFSTreeNode> ();
frontier.Enqueue(root);
// construct breadth-first tree
blacklisted.Add(start, true);
while (frontier.Count > 0)
{
BFSTreeNode currentNode = frontier.Dequeue();
foreach (Vector2Int nextPos in GetNeighbors(currentNode.id, mapHnd))
{
BFSTreeNode nextNode = new BFSTreeNode(nextPos);
currentNode.AddChild(nextNode);
// Success is when we are +1 in either direction from the destination
int xDiff = Math.Abs(nextPos.x - dest.x);
int yDiff = Math.Abs(nextPos.y - dest.y);
if (xDiff == 1 && yDiff == 0)
{
nextNode.isDest = true;
break;
}
if (yDiff == 1 && xDiff == 0)
{
nextNode.isDest = true;
break;
}
// expand search frontier
if (!blacklisted.ContainsKey(nextPos))
{
blacklisted.Add(nextPos, true);
frontier.Enqueue(nextNode);
}
}
}
// calculate distances to dest
CalculateDistances(dest, root);
}
public void AddChild(BFSTreeNode _node)
{
children.Add(_node);
}
