Perfect
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I think I'll create a Drawable base class, but it would only define a virtual Draw function, so that people can write window.Draw(object), as well as a
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class that defines the transformation stuff (position, rotation, scale, ...). sf::Mesh would inherit Drawable, high-level objects would inherit both, and user classes would have the choice.
A detail about "origin": I don't think that it was used a lot as the origin of translation and scaling, therefore I was thinking about changing it to "rotation center", which would remove all the confusion about it.