The rendering (draw) order of the tiles in this layer.
The default is 0 which is 'right-down', meaning it will draw the tiles starting from the top-left, drawing to the right and then moving down to the next row.
The draw orders are:
0 = right-down 1 = left-down 2 = right-up 3 = left-up
This can be changed via the setRenderOrder
method.