Interactive rendering of deformable objects based on a filling sphere modeling approach

Mass-spring systems have widely and effectively been used for modeling in mal-time deformable objects. Easier to implement and faster than finite elements, these systems, on the other side, suffer from several drawbacks when coming to render physically believable behaviors. Neither isotropic or anisotropic materials can be controlled easily and the large number of springs and mass points composing the model makes it fastidious to define parameters to control elongation, flexion and torsion at a macroscopic level. Another weakness is that most of the materials found in nature maintain a cunstanf or quasiconstant volume during defomtions; unfortunately, mass-spring models do not have this proper@. In this paper: we extend the current state-of-the-art in so@ tissue simulation by introducing a six-degree of freedom macroscopic elastic sphere described by mass, inertia and volumetric properties. Spheres are placed along the medial axis transform of the object whose centers are connected by a skeleton composed of a set of three-dimensional elastic links. Spheres represent internal mass, volume and contml the global deformation of the object. The surface is modeled by setting point masses on the mesh nodes and damped springs on the mesh edges. These nodes am? connected to the skeleton by individual elastic links, which contml volume conservation and transfer forces between the surface and volumetric model. Using this framework we also present an eflcient method to approximate collision detection between multiple bodies in real-time.