lib/rotjs-library/src/map/dividedmaze.js

/**
 * @class Recursively divided maze, http://en.wikipedia.org/wiki/Maze_generation_algorithm#Recursive_division_method
 * @augments ROT.Map
 */
ROT.Map.DividedMaze = function(width, height) {
	ROT.Map.call(this, width, height);
	this._stack = [];
}
ROT.Map.DividedMaze.extend(ROT.Map);

ROT.Map.DividedMaze.prototype.create = function(callback) {
	var w = this._width;
	var h = this._height;
	
	this._map = [];
	
	for (var i=0;i<w;i++) {
		this._map.push([]);
		for (var j=0;j<h;j++) {
			var border = (i == 0 || j == 0 || i+1 == w || j+1 == h);
			this._map[i].push(border ? 1 : 0);
		}
	}
	
	this._stack = [
		[1, 1, w-2, h-2]
	];
	this._process();
	
	for (var i=0;i<w;i++) {
		for (var j=0;j<h;j++) {
			callback(i, j, this._map[i][j]);
		}
	}
	this._map = null;
	return this;
}

ROT.Map.DividedMaze.prototype._process = function() {
	while (this._stack.length) {
		var room = this._stack.shift(); /* [left, top, right, bottom] */
		this._partitionRoom(room);
	}
}

ROT.Map.DividedMaze.prototype._partitionRoom = function(room) {
	var availX = [];
	var availY = [];
	
	for (var i=room[0]+1;i<room[2];i++) {
		var top = this._map[i][room[1]-1];
		var bottom = this._map[i][room[3]+1];
		if (top && bottom && !(i % 2)) { availX.push(i); }
	}
	
	for (var j=room[1]+1;j<room[3];j++) {
		var left = this._map[room[0]-1][j];
		var right = this._map[room[2]+1][j];
		if (left && right && !(j % 2)) { availY.push(j); }
	}

	if (!availX.length || !availY.length) { return; }

	var x = availX.random();
	var y = availY.random();
	
	this._map[x][y] = 1;
	
	var walls = [];
	
	var w = []; walls.push(w); /* left part */
	for (var i=room[0]; i<x; i++) { 
		this._map[i][y] = 1;
		w.push([i, y]); 
	}
	
	var w = []; walls.push(w); /* right part */
	for (var i=x+1; i<=room[2]; i++) { 
		this._map[i][y] = 1;
		w.push([i, y]); 
	}

	var w = []; walls.push(w); /* top part */
	for (var j=room[1]; j<y; j++) { 
		this._map[x][j] = 1;
		w.push([x, j]); 
	}
	
	var w = []; walls.push(w); /* bottom part */
	for (var j=y+1; j<=room[3]; j++) { 
		this._map[x][j] = 1;
		w.push([x, j]); 
	}
		
	var solid = walls.random();
	for (var i=0;i<walls.length;i++) {
		var w = walls[i];
		if (w == solid) { continue; }
		
		var hole = w.random();
		this._map[hole[0]][hole[1]] = 0;
	}

	this._stack.push([room[0], room[1], x-1, y-1]); /* left top */
	this._stack.push([x+1, room[1], room[2], y-1]); /* right top */
	this._stack.push([room[0], y+1, x-1, room[3]]); /* left bottom */
	this._stack.push([x+1, y+1, room[2], room[3]]); /* right bottom */
}