Efficient Simulation of Volumetric Deformable Objects in Unity3D: GPU-Accelerated Position-Based Dynamics

Abstract

This paper proposes an efficient approach for simulating volumetric deformable objects using the Position-Based Dynamics (PBD) method. Volumetric bodies generated by TetGen are used to represent three-dimensional objects, which accurately capture complex shapes and volumes. However, when a large number of constraints are applied to the system to solve using serialized algorithms on central processing units (CPU), the computational cost can become a bottleneck of the simulation. To address this issue, the proposed implementation algorithm takes advantage of graphic processing unit (GPU) acceleration and parallel processing to improve the efficiency of the simulation. We propose two specific contributions: firstly, the use of the PBD method with volume constraint for tetrahedral elements to simulate volumetric deformable objects realistically; secondly, an efficient GPU-accelerated algorithm for implementing the PBD method that significantly improves computational efficiency. We also applied the node-centric and constraint-centric algorithms to solve the stretch constraint in the GPU-based algorithm. The implementation was performed using Unity3D. The compute shader feature of Unity3D was utilized to perform thousands of parallel computations in a single pass, making it possible to simulate large and complex objects in real-time. The performance of the simulation can be accelerated by using GPU-based methods with stretch and bending constraints, which provides significant speedup factors compared to using only the CPU for deformable objects such as Bunny, Armadillo, and Dragon. The constraint-centric and node-centric GPU approaches provide speedup factors of up to 8.9x and 8x, respectively, while the GPU-based methods with all types of constraints exhibit a slight decrease but still operate at real-time speeds. Overall, this approach enables the simulation of complex and irregular shapes with plausible and realistic results, while also achieving speed, robustness, and flexibility. Additionally, the proposed approach can be applied to general simulation and other game engines that support GPU-based acceleration.