Speeding up adding thousands of bodies in warp.sim

[shi-eric]

Discussed in https://github.com/NVIDIA/warp/discussions/240

^{Originally posted by knauth June 18, 2024} I'm running a simulation which involves many thousands of bodies interacting. Each body has ~20 collision spheres. It's very slow to add these bodies using "naive" add_body and add_shape_sphere methods on ModelBuilder. The thing is that the bodies are not unique- their properties are already quantized to a lookup table, where each body has one of about 100 possible sizes and shapes. Is there a way to capitalize on this? In other simulation tools like Blender I've found it very advantageous to copy existing bodies and simply change their location.

Any advice on optimizing this would be appreciated!