Authors: Craig Rose and Ian Lewis
Soft body modelling in computer games aims to achieve convincing real time visualisations of the interaction of deformable objects within rich game world environments. Real world objects display a wide range of deformation types including elastic, plastic, global, local, and inhomogeneous behaviours where there may be a mix of more than one of these in varying degrees in a single contiguous object. In games, solutions which achieve these effects are dominated by mass-spring models and the finite element method (FEM). Each of these physics based models requires significant computation time, and effort on the part of the model designer to tune parameters, to get the desired effects. As an alternative to these approaches we have investigated the use of the Generalised ChainMail algorithm in conjunction with a squishy map. Generalised ChainMail treats the vertices of the 3D model's mesh as linked elements which must move to conform to the stretchiness and compressibility of the modelled material. These stretch and compression factors are represented by heuristics rather than relying on computational convergence of a physical model. The squishy map uses an image to map the stretch and compression factors to a mesh in the same fashion as a UV mapped texture. This approach offers the prospects of an easily tuneable model displaying variations in squishiness across its surface which is not excessively demanding on resources. We have demonstrated that such variable squishiness can be achieved using this approach and that after generating a suitable adjacency list from the original mesh the squishy map can be readily applied to arbitrary meshes.
Keywords: soft body modelling; ChainMail; computer games; squishiness; squishy map