Playing around with depth-first maze generation

Written on a flight from SEA->SFO
JackDanger · Feb 13, 2012 · c31f830 · c31f830
commit c31f830
Showing 1 changed file with 181 additions and 0 deletions.
diff --git a/maze.rb b/maze.rb
@@ -0,0 +1,181 @@
+
+class Maze
+
+  attr_accessor :width, :height,
+                :grid,
+                :origin, :finish
+
+  def initialize width, height
+    @width, @height = width, height
+    @grid = Array.new(width) { Array.new(height) }
+    (0...width).each do |column|
+      (0...height).each do |row|
+        grid[column][row] = Cell.new column, row
+      end
+    end
+    select_openings
+    explore origin
+    finish.walls[outlet_from(finish.x, finish.y)] = false
+    origin.walls[outlet_from(origin.x, origin.y)] = false
+  end
+
+  def to_html
+    out header
+    out '<table>'
+    (0...height).each do |y|
+      out '<tr>'
+      (0...width).each do |x|
+        out grid[x][y].to_html
+      end
+      out '</tr>'
+    end
+    out '</table>'
+    out '</body></html>'
+    out
+  end
+
+  protected
+
+    def out string = nil
+      @out ||= ''
+      @out << string if string
+      @out
+    end
+
+    def header
+      <<-EOCSS
+      <html><style>
+        table, tr, td {
+          font-size: 10px;
+          padding:0; margin:0; border-spacing: 0
+        }
+        td { border: 1px solid #FFF; width: 10px; height: 10px;
+             text-align: center; vertical-align: center; }
+        td span   { display: none }
+        td.top    { border-top-color:    #666 }
+        td.right  { border-right-color:  #666 }
+        td.bottom { border-bottom-color: #666 }
+        td.left   { border-left-color:   #666 }
+      </style><body>
+      EOCSS
+    end
+
+    def possible_openings
+      [
+        [0,           rand(height)],
+        [width-1,     rand(height)],
+        [rand(width), 0           ],
+        [rand(width), height-1    ]
+      ]
+    end
+
+    def select_openings
+      doorways = possible_openings.shuffle[0..1]
+      raise "Let's get better openings" if doorways.first == doorways.last
+      @origin = grid[doorways[0][0]][doorways[0][1]]
+      @finish = grid[doorways[1][0]][doorways[1][1]]
+    rescue
+      retry
+    end
+
+    def outlet_from x, y
+      return :left   if x == 0
+      return :right  if x == width-1
+      return :top    if y == 0
+      return :bottom if y == height-1
+    end
+
+    def explore cell
+      neighbors cell do |neighbor|
+        unless neighbor.discovered?
+          neighbor.discover_from! cell
+          explore neighbor
+        end
+      end
+    end
+
+    def neighbor_top cell
+      yield grid[cell.x][cell.y-1] if cell.y > 0
+    end
+
+    def neighbor_right cell
+      yield grid[cell.x+1][cell.y] if cell.x < width-1
+    end
+
+    def neighbor_bottom cell
+      yield grid[cell.x][cell.y+1] if cell.y < height-1
+    end
+
+    def neighbor_left cell
+      yield grid[cell.x-1][cell.y] if cell.x > 0
+    end
+
+    def neighbors cell, &block
+      [:neighbor_top,
+       :neighbor_right,
+       :neighbor_bottom,
+       :neighbor_left
+      ].shuffle.each do |neighbor|
+        send neighbor, cell, &block
+      end
+    end
+
+  class Cell
+    attr_accessor :walls, :x, :y
+
+    def self.count; @count ||= 0; end
+    def self.count= val; @count = val; end
+
+    def initialize x, y
+      @x, @y = x, y
+      @walls = {:top    => true,
+                :right  => true,
+                :bottom => true,
+                :left   => true}
+    end
+
+    def inspect
+      {:walls => walls,
+       :x => x,
+       :y => y}.inspect
+    end
+
+    def to_s
+      "(#{x},#{y})"
+    end
+
+    def to_html
+      "<td class='#{wall_status}'><span>#{@count}</span></td>\n"
+    end
+
+    def discover_from! neighbor
+      Cell.count += 1
+      @count = Cell.count
+      if neighbor.x > x
+        walls[:right] = neighbor.walls[:left] = false
+      elsif neighbor.x < x
+        walls[:left] = neighbor.walls[:right] = false
+      elsif neighbor.y > y
+        walls[:bottom] = neighbor.walls[:top] = false
+      elsif neighbor.y < y
+        walls[:top] = neighbor.walls[:bottom] = false
+      end
+    end
+
+    def discovered?
+      [true,true,true,true] != walls.values
+    end
+
+    protected
+
+      def wall_status
+        walls.select {|side, status| status }.map(&:first).join(' ')
+      end
+  end
+end
+
+
+if $0 == __FILE__
+  maze = Maze.new ARGV.shift.to_i, ARGV.shift.to_i
+  puts maze.to_html
+end