@marc that completely depends on the underlaying OpenGL and GPU processor.
Most probably 256x256 would actually take the same amount of pixels (which are x4 for RGBA)
But other dimensions might have padding, like some GPUs can only support the power of 2 rectangles, other GPUs can only support the power of 2 squares. So the power of 2 square should be the worst case padding scenario
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Most probably 256x256 would actually take the same amount of pixels (which are x4 for RGBA)
But other dimensions might have padding, like some GPUs can only support the power of 2 rectangles, other GPUs can only support the power of 2 squares. So the power of 2 square should be the worst case padding scenario
Here is a great explanation:
http://www.codeandweb.com/what-is-a-sprite-sheet