Is it necessary / efficient for the loaded graphic to be ^2 or the sprite inside a sprite sheet that you use, or both?

I'm thinking that it is, but wanted to be sure.

So, my sprites should ideally be e.g. 64x64 or 128x128 and the overall atlas should also be a relative size - e.g. 1024x1024

Only the main atlas image need be power of 2, the images on it can be any size as they are just referenced using UV coords.

Excellent, thank you.

wrong thread, excuse me.