Parallel XPBD Simulation of Modified Morse Potential - an Alternative Spring Model

Abstract

In this paper, we introduce a modified Morse potential as an alternative to the existing spring models within a massively parallel extended Position Based Dynamics (XPBD) algorithm. To date, stretching is one of the most popular constraint types of XPBD frameworks due to its simplicity, robustness and efficiency. However, the underneath mathematical expression of stretching constraint does not fully represent a spring model and behaves too stiff over a certain iteration count or damping coefficient. On the other hand, Hookean spring potential behaves softer and viscoelastic within the XPBD algorithm under the same conditions as stretching constraint. Our modified Morse potential addresses this issue by keeping the simulation of deformable models in between Hooke's law and stretching constraint. To demonstrate the benefits of modified Morse potential with higher frame rates, we develop an efficient Independent Edge Grouping algorithm for XPBD method which provides parallel processing on GPU. We compare the simulation results of cloth and volumetric models with stretching constraint, Hookean and St. Venant-Kirchhoff (STVK) spring potentials. We believe that our modified Morse potential is easy to implement and seamlessly fit into the existing XPBD frameworks.