I did like this :
Works well. I spent about one or two hours to figure out I used positionToTile instead of tileToPosition though.
By the way if the global variable blockSize is equal to a tile size I could also write :
and so on.
It's a matter of preference but I don't really like to have too much parenthesis nor dots.
I can't use tile range because I'll need to test every tile in this area later to do stuff.