private static void InitializeSearchNodes(TileMap map)
{
searchNodes = new SearchNode[levelHeight, levelWidth];
for (int x = 0; x < levelWidth; x++)
{
for (int y = 0; y < levelHeight; y++)
{
SearchNode node = new SearchNode()
{
Position = new Point(x, y),
Walkable = !map.GetIsCollision(x, y)
};
if (node.Walkable)
{
node.Neighbors = new SearchNode[4];
searchNodes[y, x] = node;
}
}
}
for (int x = 0; x < levelWidth; x++)
{
for (int y = 0; y < levelHeight; y++)
{
SearchNode node = searchNodes[y, x];
// We only want to look at the nodes that
// our enemies can walk on.
if (node == null || node.Walkable == false)
{
continue;
}
// An array of all of the possible neighbors this
// node could have. (We will ignore diagonals for now.)
Point[] neighbors = new Point[]
{
new Point (x, y - 1), // The node above the current node
new Point (x, y + 1), // The node below the current node.
new Point (x - 1, y), // The node left of the current node.
new Point (x + 1, y), // The node right of the current node
};
// We loop through each of the possible neighbors
for (int i = 0; i < neighbors.Length; i++)
{
Point position = neighbors[i];
// We need to make sure this neighbour is part of the level.
if (position.X < 0 || position.X > levelWidth - 1 ||
position.Y < 0 || position.Y > levelHeight - 1)
{
continue;
}
SearchNode neighbor = searchNodes[position.Y, position.X];
// We will only bother keeping a reference
// to the nodes that can be walked on.
if (neighbor == null || neighbor.Walkable == false)
{
continue;
}
// Store a reference to the neighbor.
node.Neighbors[i] = neighbor;
}
}
}
}
private static List<Vector2> FindFinalPath(SearchNode startNode, SearchNode endNode)
{
closedList.Add(endNode);
SearchNode parentTile = endNode.Parent;
// Trace back through the nodes using the parent fields
// to find the best path.
while (parentTile != startNode)
{
closedList.Add(parentTile);
parentTile = parentTile.Parent;
}
List<Vector2> finalPath = new List<Vector2>();
// Reverse the path and transform into world space.
for (int i = closedList.Count - 1; i >= 0; i--)
{
finalPath.Add(new Vector2(closedList[i].Position.X * 32,
closedList[i].Position.Y * 32));
}
return finalPath;
}