/// <summary>
/// Find a solution to a map.
/// </summary>
/// <param name="map">Map to solve.</param>
/// <param name="strategy">Strategy to use to solve the map.</param>
/// <returns></returns>
public static MapPath FindPath(
Map map,
ITraversalStrategy strategy,
string options = null)
{
return new MapPath(strategy.Traverse(map, options));
}
static void Main(string[] args)
{
// Display help.
if ((args.Length == 0) ||
(args[0] == "-?") ||
(args[0] == "/?") ||
(args[0].ToLower() == "help"))
{
OutputHelp();
return;
}
// Forgot to specify solution path.
if (args.Length < 2)
{
Console.WriteLine("No destination image path specified.");
return;
}
// Collect file paths.
string sourcePath = args[0];
string outputPath = args[1];
// Optional strategy option specified.
string strategyOption = null;
if (args.Length > 2)
strategyOption = args[2];
// Attempt to load the image.
Bitmap sourceImage;
try
{
sourceImage = new Bitmap(sourcePath);
}
catch (Exception)
{
Console.WriteLine("Source file is not a valid image format.");
return;
}
// TODO: Allow other strategies if time allows.
Map map = new Map(sourceImage);
MapPath path = PathFinder.FindPath(map, Strategies.BreadthFirst, strategyOption);
// No solution found.
if (path == null)
{
Console.WriteLine("No path could be found to solve the maze.");
Console.WriteLine("Are you using the correct colors?");
return;
}
PathFinder.OutputBitmap(path, map, outputPath);
System.Console.WriteLine("Solution saved successfully to " + outputPath);
}
/// <summary>
/// Loads the map.
/// </summary>
private static void LoadMap()
{
_map = new Map(10, 20);
_map.Close(1, 5);
_map.Close(2, 5);
_map.Close(3, 5);
_map.Close(4, 5);
_map.Close(5, 5);
_map.Close(6, 5);
_map.Close(7, 5);
}
/// <summary>
/// Save a solved map to an image file.
/// </summary>
/// <param name="path"></param>
/// <param name="map"></param>
/// <param name="outputPath"></param>
public static void OutputBitmap(
MapPath path,
Map map,
string outputPath)
{
// Get pixels from original map data.
byte[] pixels = path.TraceOverMap(map);
// Output the bitmap.
string extension = Path.GetExtension(outputPath);
BitmapEncoder encoder;
switch (extension)
{
default:
encoder = new BmpBitmapEncoder();
break;
case ".png":
encoder = new PngBitmapEncoder();
break;
case ".gif":
encoder = new GifBitmapEncoder();
break;
case ".tif": case "tiff":
encoder = new TiffBitmapEncoder();
break;
case ".jpg": case "jpeg":
encoder = new JpegBitmapEncoder();
break;
case ".wmp":
encoder = new WmpBitmapEncoder();
break;
}
Console.WriteLine(extension);
// TODO: Figure out why files have no compression.
int stride = map.Width * Map.BytesPerPixel;
BitmapSource bitmapSource = BitmapSource.Create(
map.Width, map.Height,
96, 96,
PixelFormats.Bgra32, null, pixels, stride);
encoder.Frames.Add(BitmapFrame.Create(bitmapSource));
using (FileStream filestream = new FileStream(outputPath, FileMode.Create))
{
encoder.Save(filestream);
}
}
/// <summary>
/// Simple way to avoid the target.
/// </summary>
/// <param name="target">The target to avoid.</param>
/// <param name="map">The map that the agent is traveling on.</param>
public void Avoid(Agent target, Map map)
{
var iterations = 0;
int newX = X, newY = Y;
var targetNode = map[target.X, target.Y];
var currentDist = map[X, Y].DistanceTo(targetNode);
// Only 10 steps are needed.
while (iterations < 20)
{
var neighbours = map.NeighbourNodes(map[newX, newY]);
// Check which neighbour node that leads furthest away from the target.
foreach (Node neighbour in neighbours)
{
if (neighbour.Closed) continue;
var tempDist = neighbour.DistanceTo(targetNode);
if (tempDist > currentDist)
{
currentDist = tempDist;
var optimalNeighbour = neighbours.IndexOf(neighbour);
newX = neighbours[optimalNeighbour].X;
newY = neighbours[optimalNeighbour].Y;
}
}
iterations++;
}
// Find the path to the target location.
Path = AStar.FindPathTo(map[X, Y], map[newX, newY], map);
Move();
}
public void FindPathWithBreadthFirstStrategy()
{
Map map;
ITraversalStrategy strategy = Strategies.BreadthFirst;
MapPath solution;
map = new Map(this.simpleMap);
solution = PathFinder.FindPath(map, strategy);
PathFinder.OutputBitmap(solution, map, "simpleSolution.png");
Assert.IsNotNull(solution);
map = new Map(this.largeMap);
solution = PathFinder.FindPath(map, strategy);
PathFinder.OutputBitmap(solution, map, "largeSolution.png");
Assert.IsNotNull(solution);
// TODO: Technically, this fails, because the path goes through
// some diagonal walls.
map = new Map(this.organicMap);
solution = PathFinder.FindPath(map, strategy);
PathFinder.OutputBitmap(solution, map, "organicSolution.png");
Assert.IsNotNull(solution);
}
/// <summary>
/// Finds the shortest path from [fleeing] to [chasing] using the AStar algorithm.
/// </summary>
/// <param name="start">The node to fleeing at.</param>
/// <param name="end">The node to chasing at.</param>
/// <param name="map">The map.</param>
/// <returns>The path as a list of nodes.</returns>
public static List<Node> FindPathTo(Node start, Node end, Map map)
{
// Create lists
var path = new List<Node>();
_open = new List<Node>();
_closed = new List<Node>();
// Create fleeing node
var tempStart = start;
tempStart.CameFrom = null;
tempStart.GScore = 0;
tempStart.FScore = tempStart.GScore + tempStart.DistanceTo(end);
AddToOpenList(tempStart);
// While open is not empty...
while (_open.Count > 0)
{
var current = _open[0];
// If we found the goal ...
if (current.Equals(end))
{
// ... Create the path.
path = ReconstructPath(current);
break;
}
_open.Remove(current);
AddToClosedList(current);
// For all neighbour nodes
foreach (var neighbour in map.NeighbourNodes(current))
{
if (neighbour.Closed) continue;
// Calculate scores.
var tentativeGScore = current.GScore + neighbour.Cost;
var tentativeFScore = tentativeGScore + neighbour.DistanceTo(end);
// If the neighbour is in the closed list and the tentativeFScore is higher
// than the neighbour's, skip it.
if (_closed.Contains(neighbour)
&& tentativeFScore >= _closed[_closed.IndexOf(neighbour)].FScore)
{
continue;
}
// If the neighbour is not in the open list, add it.
if (!_open.Contains(neighbour)
&& map.WithinMap(neighbour))
{
neighbour.CameFrom = current;
neighbour.GScore = tentativeGScore;
neighbour.FScore = tentativeFScore;
AddToOpenList(neighbour);
continue;
}
// If the neighbour is in the open list, modify it.
if (_open.Contains(neighbour)
&& map.WithinMap(neighbour))
{
var indexOfNeighbour = _open.IndexOf(neighbour);
if (tentativeFScore < _open[indexOfNeighbour].FScore)
{
_open[indexOfNeighbour].CameFrom = current;
_open[indexOfNeighbour].GScore = tentativeGScore;
_open[indexOfNeighbour].FScore = tentativeFScore;
}
}
}
}
return path;
}
/// <summary>
/// Chase the target using the aStar algorithm.
/// </summary>
/// <param name="target">The target to chase.</param>
/// <param name="map">The map the agent is traveling on.</param>
public void Chase(Agent target, Map map)
{
Path = AStar.FindPathTo(map[X, Y], map[target.X, target.Y], map);
Move();
}
