js13k tiled format

tiled.js

function getData(id, count, flip) {
	var data = "";
	switch (flip) {
		case 1: data = "|"; break;
		case 2: data = "-"; break;
		case 3: data = "+"; break;
	}
	if (id && count === 1) {
		return data + id.toString(36).toUpperCase();
	}
	while (count > 35) {
		data = data + id.toString(36) + "z";
		count -= 35;
	}
	if (count > 0) {
		data = data + id.toString(36) + count.toString(36);
	}
	return data;
}

tiled.registerMapFormat("js13k", {
	name: "js13k format",
	extension: "json",
	write: function(map, fileName) {
		var data = "";
		for (var i = 0; i < map.layerCount; ++i) {
			var layer = map.layerAt(i);
			if (!layer.isTileLayer) continue;
			if (i) data = data + ",";
			var lastId = 0;
			var lastFlip = 0;
			var count = 0;
			for (var y = 0; y < layer.height; ++y) {
				for (var x = 0; x < layer.width; ++x) {
					var cell = layer.cellAt(x, y);
					var id = cell.empty ? 0 : cell.tileId + 10;
					var flip = 0;
					if (cell.flippedHorizontally) flip += 1;
					if (cell.flippedVertically) flip += 2;
					if (id !== lastId || flip !== lastFlip) {
						if (count > 0) {
							data = data + getData(lastId, count, lastFlip);
							count = 0;
						}
						lastId = id;
						lastFlip = flip;
					}
					count++;
				}
			}
			if (lastId > 0) {
				data = data + getData(lastId, count, lastFlip);
			}
		}
		var file = new TextFile(fileName, TextFile.WriteOnly);
		file.write(data);
		file.commit();
	}
});