I'm guessing the rectangle has the smaller footprint as I would be calling only one material vs two for the two 512 method. Can anyone confirm/deny this?
One texture is potentially better, but the difference is relatively minor or negligable, especially if you end up sampling the original texture twice anyway.
less texture calls with the rectangle, and if your using it for a unwraped model, possible less UV splits since you can have longer islands and still maintain proper scale.
for a unwrapped mesh i would go rectangle, if your speaking of tileing textures and trim sheets i would go 2 textures.
One thing to take into account is technical limitations as well, some engines such as Unreal prefer the use of square textures especially on mobile platforms.
I think unless it is power of two streaming does not matter that much. (don't spread fames, for mobile it is best if it is power of two, it does not need to be square to have most optimal performance. compression is best when power of two, not just squared), this does not apply for GUI. GUI you want pixel perfect so you want to keep that in original resolution and without compression for maximal quality (I think of truecolor scale).
If you are using both textures on same material and they are not same property i would say no benefit. When same property like mask and diffuse on same map or compressed channels then for sure use one texture cause this eliminates calls to graphic core for proper texture. Benefits should be obvious.
Non *2 textures are totally fine on hardware that is not mobile based, basically anything that has the same power of that the PS2 shouldn't be using non*2 textures, although they used plenty of rectangular textures in FF series.
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for a unwrapped mesh i would go rectangle, if your speaking of tileing textures and trim sheets i would go 2 textures.
If you are using both textures on same material and they are not same property i would say no benefit. When same property like mask and diffuse on same map or compressed channels then for sure use one texture cause this eliminates calls to graphic core for proper texture. Benefits should be obvious.
Non *2 textures are totally fine on hardware that is not mobile based, basically anything that has the same power of that the PS2 shouldn't be using non*2 textures, although they used plenty of rectangular textures in FF series.