Maze

Generate a maze with the power of lenses!

Maze is output to STDOUT in PBM format.

Example

Generate a random 6x6 maze, output to a pbm file, then convert to a png with ImageMagick:

maze 6 6 > maze.pbm
convert maze.pbm maze.png

Usage

maze <width/2> <height/2> <entropy>*

The width and height of the maze are actually twice the number of pixels of the argument. This is due to the minimum number of pixels required for a path including those of the walls.

The PBM output should be usable directly from the terminal for those with a keen eye:

Entropy refers to a sequence of digits used for the cycled decision data. If omitted, the built-in pseudo-random number generator will be used.

For example:

maze 12 12 0
maze 12 12 0 1
maze 12 12 0 0 1
maze 12 12 0 0 0 1
maze 12 12 0 1 0 2 1

Algorithm

step :: Action ()
step = top >>= visit >> getNeighbours >>= mapM_ proceed >> pop

proceed :: Vector -> Action ()
proceed cell = not `fmap` visited cell >>= flip when (removeWall cell >> push cell >> step)

The algorithm is a simple backtracking depth-first-search, with randomness introduced through user-supplied entropy, or the System.Random RNG.