Thanks, yes it helps a lot ! The idea of the interface is very good, I would have never thought of it while it's quite simple. However, is it possible to create several interfaces for each animation I need ? (rain, snow, etc). I think it's possible, but the true question is : how can I call them one by one? If I create these different interfaces all as Miscellaneous class, then I can use the action Show/Hide interface (class Miscellaneous), but how will Visionaire know which is the one I want to display ?
I'm not sure it's well explained.... If it's not possible I'll try with the code you give above.
Also if you want to save memory/loading time then you could make the rain animation about half or quarter of the size
That's what I'm doing already. It was your idea at the beginning

And it's great.