  We propose and explore a new, general-purpose method for the implicit time
integration of elastica. Key to our approach is the use of a mixed variational
principle. In turn its finite element discretization leads to an efficient
alternating projections solver with a superset of the desirable properties of
many previous fast solution strategies. This framework fits a range of elastic
constitutive models and remains stable across a wide span of timestep sizes,
material parameters (including problems that are quasi-static and approximately
rigid). It is efficient to evaluate and easily applicable to volume, surface,
and rods models. We demonstrate the efficacy of our approach on a number of
simulated examples across all three codomains.
