In the previous demonstration animation, we interpolated joint angles. It is also possible to interpolate the positions of handle constraints. This forces handles to follow simple lines of motion which may be more realistic and closer to what the animator desires.
We wrote code to save and load constraint animation files and tested out the YMCA example from above. However, this worked much worse than simply interpolating joint angles: we couldn't even get the figure to reliably assume the same positions, given a few constraints on feet and hands. We could produce an animation, but it was unrecognizable and awkward. The awkwardness of the positions we selected may be a factor.