Comparative Study of Iteration and Coefficient Influence on Volume Preservation in Position-based Dynamics Simulation.

We proposed a practical approach with position-based dynamics (PBD) to simulate the volume of a deformable body. A variety of materials were simulated using the general constraints of PBD such as stretch, bending, and volume constraints. The method for the constraint system based on PBD was fast, unconditionally stable, and controllable. However, it also had limitations and challenges that need to be addressed. The animation of the simulator required high-performance speed, therefore we used the parallelization technique of PBD since the multi-core system and massively parallel GPUs were more efficient than the naïve approach (serialize method). Since we chose Unity3D and OpenGL as the main platforms, we used the compute shader as the kernel to execute the program to solve the system of constraints. Even though the PBD-based approach was fast, the coefficients were inaccurate to maintain the object’s volume. Therefore, we demonstrated the complexity in the calculation of GPU-based PBD compared to CPU-based PBD in each different case of constraint type correlated with the coefficients. We also evaluated the effectiveness of various constraint methods within the PBD approach by comparing the error in the volume of the deformable object.