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recent PBD papers

Posted: Wed Nov 04, 2020 8:47 pm
by raigan2
I've been getting back into sim/pbd stuff after nearly a decade, and there have been a couple really interesting Position Based Dynamics papers released recently that I wanted to put on everyone's radar:

This one is really mind-blowing -- tiny time steps with a single-solver-iteration per step behaves a lot better than bigger steps with multiple solver iterations: ... lsteps.pdf

And more recently, a fully PBD-based rigid body simulation: ... Bodies.pdf

it looks like they still haven't solved the "collision detection needs to be moved into the solver, which is a big bottleneck" problem -- they're still doing "speculative constraints" (generating collision constraints for all *nearby* objects and then during solving skipping any that don't penetrate), and at a lower rate than the tiny steps. I wonder if an incremental approach might help, since when you're ticking at 1-2.4khz things are barely moving each tick.

Re: recent PBD papers

Posted: Thu Feb 18, 2021 5:03 pm
by kiaran
I'm a big fan of the Detailed Rigid Bodies paper for a few reasons.

For one, it explains the guts of rigid body simulation better than other papers in the field that typically reference a dense thesis or abstract mathematical paper. There's a lot of distilled wisdom in that paper which is great for engineering applications.

Secondly, the paper eliminates a lot of the concerns with PBD around using real-world units.

I don't know of any engines that are using the "many substeps, single iteration" method yet. Though they demonstrate very promising results with it.