洋書の参考書でどうしても分からない部分があります。誰か教えて下さい．

After you have a valid quadric object, you can use it to draw any number ofshapes,
and the same object canbe used to draw disks, cylinders, cones, and spheres.
So, you may wonder, if a single quadric can be used to draw any shape and as many of each shape as you want,
why would you want to create more than one? And for that matter, if you only need one, couldn't OpenGL just manage that behind the scenes,
and not require you to create a quadric object?
Well, in truth, you could get away with using a single quadric object, and in some applications, that's perfectly acceptable.
But remember that quadric objects are used to store state information about the shapes you want to draw.
If you use a single quadric, all shape drawn with it must use the same states, or else you need to change states between shapes.
Because state changes aren't free, unless you really do want all your shapes to share the same state variable, it's probably going to be
more efficient to create multiple quadrics.

クワドリクスオブジェクトが一つで色々な形状を作れるのはおかしい！オブジェクトが一つだけだと形状の状態情報を形状ごとに変える必要があり、
それは自由じゃないから効率が良い（悪いんじゃないの？）！
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