Show HN: Soft Body Jiggle Physics

(github.com)

36 points | by vesperance 4 days ago

8 comments

  • sameersri2004 3 hours ago
    Could be used for soft sea fish models
  • embedding-shape 4 hours ago
    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 3 hours ago
      That's probably the intent given the link in their github bio
      • embedding-shape 2 hours 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 4 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 3 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 2 hours 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 4 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.

  • fooqux 1 hour ago
    Looks well documented. I applaud the author for not just sharing code, but taking the time to teach how to use it and how it was made.
    • fwip 21 minutes ago
      I dunno, the readme is clearly LLM vomit. It's hard to praise docs that might not even have been read yet.
  • deafpolygon 2 hours ago
    Doing the lord’s work, advancing the human race forward.
  • Razengan 3 hours ago
    I had vastly different expectations, though I suppose this could lead to them..
    • blensor 2 hours ago
      Check the github user profile ;)
      • swyx 27 minutes ago
        why would a "live cam show" company need jiggle physics?
  • bitwize 1 hour ago
    Something something men of culture
  • patcon 2 hours 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