For IK to do this, it requires two goals or something that acts similarly.  Look at any other 3D application leg IK system where the foot plants for, say, walk cycle foot falls.  There are two goals (at the least) or a control box that acts similarly to constrain the foot from penetrating the 'floor'.

Some applications actually implement a 'constraint' that can be applied to links in the IK chain.  Some may go for physical dynamics or collision detection.  It is assured that Poser isn't going to these extremes or levels of implemention.

What do you think?

C makes it easy to shoot yourself in the foot. C++ makes it harder, but when you do, you blow your whole leg off.

 -- Bjarne Stroustrup

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