Show HN: Soft Body Jiggle Physics

23 points by vesperance 5 days ago

A simple and fundamental standard for dynamic soft body dynamics.

sameersri2004 - an hour ago

Could be used for soft sea fish models

Nice donut in the demo, but would love to see a human model for a more fun demo :) Ideally with a proper weight map for the different body parts too, seems well done enough that you could get really close to something realistic.

hgoel - an hour ago

That's probably the intent given the link in their github bio
- embedding-shape - 14 minutes ago
  
  Huh, might seem so, although this seem unrelated but obvious the domains are... Similar.
  Wish author wasn't such a chicken if it was intended for body parts, show the demo in the README, I think it's still legal isn't it?

WizardK - 2 hours ago

Nice to see someone else doing physics in the browser. And this looks well put together, keeping the engine dependency free and separate from the renderer is a good call, that is what makes it easy to reuse in Three or Babylon.

One question: how does it hold up when the framerate changes? Spring jiggle like this usually either blows up or feels different when the timestep moves around. Are you using a fixed timestep, or just relying on the damping to keep it stable?

bruce343434 - 2 hours ago

The accumulator pattern keeps simulations stable in the face of variable frame rate. Accumulate the frame dt into an accum variable. If accum>fixed_physics_dt then step_physics until false. I'm assuming the author did something like that because it's standard practise.
https://www.gafferongames.com/post/fix_your_timestep/
- saltcured - 7 minutes ago
  
  Well, as long as the step rate remains well above the Nyquist limit? Otherwise, your simulation will start to have something akin to aliasing errors.
  That is one place where an analytical solution is a benefit, even if it is a bit less realistic. You just have a position(t) parametric function you can evaluate when rendering sporadically.
embedding-shape - 2 hours ago

> when the timestep moves around
Why would the physics timestep move around? Typically you keep that fixed and separate, especially not locked to the display framerate, physics get really wonky then regardless of what you do.

patcon - 13 minutes ago

Another example of the adult entertainment industry driving critical technology infrastructure forward...?

Makes me wonder: Does the adult entertainment industry have its own variant of the military's DARPA, or is it truly decentralized in its innovation and standards work? Haha

deafpolygon - 33 minutes ago

Doing the lord’s work, advancing the human race forward.

Razengan - an hour ago

I had vastly different expectations, though I suppose this could lead to them..

blensor - 27 minutes ago

Check the github user profile ;)