@grey : I understand that it isn't the best solution. This structure is to keep some compatibility with my game editor and my previous game code. I don't know why but i've some difficulty to obtain an easy implementation. Perhaps tired at the end of the year !
my english is limited so it's difficult to me to explain my choice.
I need a virtual not drawing screen before and another after the main drawn screen : to progressive draw portions of large obstacles and check collision (see picture from game and editor :)

The editor use x,y to reference a cell.
my english is limited so it's difficult to me to explain my choice.
I need a virtual not drawing screen before and another after the main drawn screen : to progressive draw portions of large obstacles and check collision (see picture from game and editor :)

The editor use x,y to reference a cell.