private function getExtent(dx:int, dy:int):uint
        {
            var start:Point2i = player.getIndex();
            var result:uint = 1;
            if (dx > 0)
            {
                if (!Tile.isSlippery(getTile(start.x + 1, start.y)))
                {
                    return result;
                }
                for (var i:int = start.x + 1; i < cols; i += 1)
                {
                    var tile:int = getTile(i, start.y);
                    if (Tile.isSlippery(tile))
                    {
                        result += 1;
                        var next:int = getTile(i + 1, start.y);
                        if (!Tile.isWalkable(next))
                        {
                           result -= 1;
                        }
                    }
                    else
                    {
                        break;
                    }
                }
            }
            else if (dx < 0)
            {
                if (!Tile.isSlippery(getTile(start.x - 1, start.y)))
                {
                    return result;
                }
                for (var k:int = start.x - 1; k >= 0; k -= 1)
                {
                    var tile2:int = getTile(k, start.y);
                    if (Tile.isSlippery(tile2))
                    {
                        result += 1;
                        var next2:int = getTile(k - 1, start.y);
                        if (!Tile.isWalkable(next2))
                        {
                           result -= 1;
                        }
                    }
                    else
                    {
                        break;
                    }
                }
            }
            else if (dy > 0)
            {
                if (!Tile.isSlippery(getTile(start.x, start.y + 1)))
                {
                    return result;
                }
                for (var r:int = start.y + 1; r < rows; r += 1)
                {
                    var tile3:int = getTile(start.x, r);
                    if (Tile.isSlippery(tile3))
                    {
                        result += 1;
                        var next3:int = getTile(start.x, r + 1);
                        if (!Tile.isWalkable(next3))
                        {
                           result -= 1;
                        }
                    }
                    else
                    {
                        break;
                    }
                }
            }
            else if (dy < 0)
            {
                if (!Tile.isSlippery(getTile(start.x, start.y - 1)))
                {
                    return result;
                }
                for (var c:int = start.y - 1; c >= 0; c -= 1)
                {
                    var tile4:int = getTile(start.x, c);
                    if (Tile.isSlippery(tile4))
                    {
                        result += 1;
                        var next4:int = getTile(start.x, c - 1);
                        if (!Tile.isWalkable(next4))
                        {
                           result -= 1;
                        }
                    }
                    else
                    {
                        break;
                    }
                }
            }
            return result;
        }