Yup, that's the appropriate question.  There are quite a few ways to
do collision detection; some are quite fast but not precise.  Those
could be incorporated into the animation code.

The cloth and hair rooms were built by other companies and connected
into Poser.   The animation code is an internal part of Poser, and (so far anyway)
none of Poser's owners have seen fit to make any important changes to
internal code.  Except for the Layers bit, which doesn't work right, there
haven't been any improvements since P4.

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