Patent ID: 7363199

Claim:
A method of simulating soft body movement in a data processing simulator, the method comprising the steps of: defining the surface of a soft body as a closed mesh represented by a plurality of points in space connected by edges, such that no edges are defined within the surface of the soft body; representing each point of the mesh with a point mass, the motion of which is governed by laws of motion; representing forces acting on the point masses with a combination of sets of corresponding pairs of: skin forces connecting pairs of point masses, and volumetric forces for maintaining relative positions of arbitrary sets of points, introducing no net linear or rotational forces on the soft body; and simulating the movement of the soft body; wherein a volumetric force component is determined by defining: a reference shape, comprising a set of points in space that specify the rest state for the set of points affected by the volumetric force component, a reference set that specifies a mapping between points in the soft body and points in the reference shape, and a reference frame that determines the position and orientation of the reference shape in space; determining the position and orientation of the reference frame as the points of the soft body move in space; and determining a set of forces to apply to the point masses of the soft body such that the points tend to maintain the reference shape without introducing any net linear or rotational force about the centroid of the set of points; and wherein shape-restoring forces of a volumetric force component are calculated as a function of the relative positions between points in the soft body specified by the reference set and the corresponding points in the reference shape transformed by the reference frame.