/// <summary>
/// Solves the specified maze.
/// </summary>
/// <param name="maze">The maze.</param>
/// <param name="start">The start.</param>
/// <param name="end">The end.</param>
/// <returns>The solution.</returns>
public IEnumerable<Cell> Solve(bool[,] maze, Cell start, Cell end)
{
var stack = new Stack<Cell>();
stack.Push(start);
var visited = new bool[maze.GetLength(0), maze.GetLength(1)];
var previousCell = new Cell[maze.GetLength(0), maze.GetLength(1)];
Func<Cell, bool> hasRightWall = cell => maze[cell.I, cell.J + 1];
Func<Cell, bool> hasLeftWall = cell => maze[cell.I, cell.J - 1];
Func<Cell, bool> hasTopWall = cell => maze[cell.I - 1, cell.J];
Func<Cell, bool> hasBottomWall = cell => maze[cell.I + 1, cell.J];
while (stack.Count > 0)
{
var temp = stack.Pop();
if (temp.Equals(end))
{
var foundPath = new List<Cell>();
while (true)
{
foundPath.Add(temp);
if (temp.Equals(start))
{
break;
}
temp = previousCell[temp.I, temp.J];
}
foundPath.Reverse();
return foundPath;
}
visited[temp.I, temp.J] = true;
if (!hasLeftWall(temp) && !visited[temp.I, temp.J - 2])
{
stack.Push(new Cell(temp.I, temp.J - 2));
previousCell[temp.I, temp.J - 2] = temp;
}
if (!hasRightWall(temp) && !visited[temp.I, temp.J + 2])
{
stack.Push(new Cell(temp.I, temp.J + 2));
previousCell[temp.I, temp.J + 2] = temp;
}
if (!hasTopWall(temp) && !visited[temp.I - 2, temp.J])
{
stack.Push(new Cell(temp.I - 2, temp.J));
previousCell[temp.I - 2, temp.J] = temp;
}
if (!hasBottomWall(temp) && !visited[temp.I + 2, temp.J])
{
stack.Push(new Cell(temp.I + 2, temp.J));
previousCell[temp.I + 2, temp.J] = temp;
}
}
// no solution found
return null;
}
/// <summary>
/// Get the position for the specified cell.
/// </summary>
/// <param name="cell">
/// The cell.
/// </param>
/// <param name="z">
/// The z.
/// </param>
/// <returns>
/// The position.
/// </returns>
private Point3D GetPosition(Cell cell, double z)
{
return this.GetPosition(cell.I, cell.J, z);
}
/// <summary>
/// Generates the maze.
/// </summary>
/// <returns>A maze.</returns>
public bool[,] Generate()
{
int width = this.Width;
int height = this.Height;
if (width % 2 == 0)
{
throw new InvalidOperationException("Width must be an odd number");
}
if (height % 2 == 0)
{
throw new InvalidOperationException("Height must be an odd number");
}
bool[,] maze = new bool[height, width];
// Initialize maze (all walls intact)
for (int i = 0; i < height; i++)
{
for (int j = 0; j < width; j++)
{
maze[i, j] = i % 2 == 0 || j % 2 == 0;
}
}
var stack = new Stack<Cell>();
var current = new Cell(1, 1);
stack.Push(current);
Func<int, int, bool> isVisited = (i, j) => maze[i - 1, j] && maze[i + 1, j] && maze[i, j - 1] && maze[i, j + 1];
var random = new Random(this.Seed);
while (stack.Count > 0)
{
var neighbours = new List<Cell>();
int i = current.I;
int j = current.J;
// Find unvisited neighbours
if (i > 1 && isVisited(i - 2, j))
{
neighbours.Add(new Cell(i - 2, j));
}
if (j > 1 && isVisited(i, j - 2))
{
neighbours.Add(new Cell(i, j - 2));
}
if (i + 2 < height && isVisited(i + 2, j))
{
neighbours.Add(new Cell(i + 2, j));
}
if (j + 2 < width && isVisited(i, j + 2))
{
neighbours.Add(new Cell(i, j + 2));
}
if (neighbours.Count > 0)
{
var next = neighbours[random.Next(neighbours.Count)];
// break the wall between current and next cell
int ii = (next.I + current.I) / 2;
int jj = (next.J + current.J) / 2;
maze[ii, jj] = false;
stack.Push(current);
current = next;
}
else
{
current = stack.Pop();
}
}
return maze;
}
/// <summary>
/// Creates the maze.
/// </summary>
private void CreateMaze()
{
// Generate the maze
var mazeGenerator = new MazeGenerator2 { Width = 21, Height = 31 };
this.maze = mazeGenerator.Generate();
// Solve the maze
var solver = new MazeSolver1();
var start = new Cell(1, 1);
var end = new Cell(this.maze.GetLength(0) - 2, this.maze.GetLength(1) - 2);
var solution = solver.Solve(this.maze, start, end);
int m = this.maze.GetUpperBound(0) + 1;
int n = this.maze.GetUpperBound(1) + 1;
this.offsetX = -m * 0.5;
this.offsetY = -n * 0.5;
this.WallsGeometry = this.CreateMazeGeometry(this.maze);
this.GroundGeometry = this.CreateGroundGeometry(this.maze, 1, -0.005);
this.SolutionGeometry = this.CreateSolutionGeometry(solution);
}
