/// <summary>
/// Constructor.
/// </summary>
public Pathfinder(Map map)
{
levelWidth = map.Width;
levelHeight = map.Height;
InitializeSearchNodes(map);
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="map">Current level's map.</param>
public Pathfinder(Map map)
{
this.levelWidth = map.Width;
this.levelHeight = map.Height;
this.InitializeSearchNodes(map);
// FOR TEST
this.Target = new Point(map.Width - 1, map.Height - 1);
}
/// <summary>
/// Splits the level up into a grid of nodes.
/// </summary>
private void InitializeSearchNodes(Map map)
{
searchNodes = new SearchNode[levelWidth, levelHeight];
// Create node for each tile.
CreateNodeForEachTile(map);
// Connect each node with its neighbours.
ConnectEachNodeWithNeighbours();
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// </summary>
protected override void Initialize()
{
// Initialize window
GraphicsInitialization();
this.map = new Map(this);
pathfinder = new Pathfinder(map);
Stack<Vector2> path = pathfinder.FindPath(new Point(0, 0), map, new Point(12, 26));
foreach (Vector2 point in path)
{
System.Diagnostics.Debug.WriteLine(point);
}
zombie = new DrawableObject(this, Vector2.Zero);
zombie.Path = path;
base.Initialize();
}
// <summary>
/// Splits our level up into a grid of nodes.
/// </summary>
private void InitializeSearchNodes(Map map)
{
searchNodes = new SearchNode[levelWidth, levelHeight];
//For each of the tiles in our map, we
// will create a search node for it.
for (int x = 0; x < levelWidth; x++)
{
for (int y = 0; y < levelHeight; y++)
{
//Create a search node to represent this tile.
SearchNode node = new SearchNode();
node.Position = new Point(x, y);
// Our enemies can only walk on grass tiles.
node.Walkable = map.GetIndex(x, y) == 0;
// We only want to store nodes
// that can be walked on.
if (node.Walkable == true)
{
node.Neighbors = new SearchNode[4];
searchNodes[x, y] = node;
}
}
}
// Now for each of the search nodes, we will
// connect it to each of its neighbours.
for (int x = 0; x < levelWidth; x++)
{
for (int y = 0; y < levelHeight; y++)
{
SearchNode node = searchNodes[x, y];
// 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.X, position.Y];
// 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;
}
}
}
}
/// <summary>
/// Ininitializes the srating node and add it to the open list.
/// </summary>
private void InitializeStartnode(Point currentPosition, Map map, List<SearchNode> openList)
{
searchNodes[currentPosition.X, currentPosition.Y].G = 0;
searchNodes[currentPosition.X, currentPosition.Y].CalculateHValue(map, Target);
openList.Add(searchNodes[currentPosition.X, currentPosition.Y]);
searchNodes[currentPosition.X, currentPosition.Y].InOpenList = true;
}
/// <summary>
/// Do the pathfinding from current point
/// </summary>
public Stack<Vector2> FindPath(Point startPoint, Map map, Point endPoint)
{
var startNode = searchNodes[startPoint.X, startPoint.Y];
var endNode = searchNodes[endPoint.X, endPoint.Y];
// Check if current position is outside the map
if ((startPoint.X > map.Width - 1 || startPoint.X < 0) ||
(startPoint.Y < 0 || startPoint.Y > map.Height - 1))
{
throw new ApplicationException("Starting point for search is outside the boundaries of the map!");
}
var openList = new List<SearchNode>();
var closeList = new List<SearchNode>();
InitializeStartnode(startPoint, map, openList);
while (openList.Count > 0)
{
// Finds next active node (minimal F value)
SearchNode activeNode = FindBestNode(openList);
ProcessNeighbours(activeNode, openList);
// Drop current active node from drop list
openList.Remove(activeNode); // TO BE cONSIDERED IT'S SLOW!!!
activeNode.InOpenList = false;
closeList.Add(activeNode);
activeNode.InClosedList = true;
// Check if target is found.
if (searchNodes[endPoint.X, endPoint.Y].InClosedList)
{
break; // TODO Return path.
}
}
// Save the path
var path = FindFinalPath(startNode, endNode, closeList);
return path;
}
/// <summary>
/// Creates node for each tile.
/// </summary>
private void CreateNodeForEachTile(Map map)
{
for (int coordX = 0; coordX < levelWidth; coordX++)
{
for (int coordY = 0; coordY < levelHeight; coordY++)
{
var node = new SearchNode();
node.Position = new Point(coordX, coordY);
// Mark walkable terrain. 0 represent path on map grid.
node.Walkable = map.GetValue(coordX, coordY) == WalkableLandValue;
// Store only walkable nodes.
if (node.Walkable)
{
node.Neighbours = new List<SearchNode>(); // TO BE CONSIDERED!!!
searchNodes[coordX, coordY] = node;
}
}
}
}
/// <summary>
/// Calculates the H value.
/// </summary>
public void CalculateHValue(Map map, Point target)
{
this.H = 10 * (Math.Abs(this.Position.X - target.X) + Math.Abs(this.Position.Y - target.Y));
}