June 6, 2026
Things got bouncy fast
Show HN: Soft Body Jiggle Physics
A wobbly web demo got people cheering, thirsting, and asking the real physics questions
TLDR: A browser-based demo shows an easy way to add believable wobble to moving objects, and developers liked how reusable it looks. But the comments instantly turned into a mix of serious questions about whether it works reliably and jokes about the kind of “demo” people were secretly hoping for.
A Show HN post about jiggle physics — yes, the famously chaos-attracting animation trick that makes soft parts wobble when something moves — landed with exactly the kind of comment-section energy you’d expect. The creator, xlovecam, pitched it as a clean little browser demo and a reusable “standard” for adding bounce and sway to objects in games and graphics. Translation for non-graphics people: it’s a neat way to make things look squishy without going full science-lab simulation. And the crowd immediately split into two camps: the impressed engineers and the extremely online jokesters.
On the serious side, one commenter praised the project for keeping the motion engine separate from the visuals, calling that a smart move because it makes the system easier to reuse elsewhere. But they also raised the kind of practical question that can start a nerd fight fast: does it still behave properly when frame rates change, or does the wobble go haywire? That’s the sober, grown-up debate underneath all the giggling.
And yes, there was giggling. One user saw the demo donut and instantly asked for a human model with more detailed body-part mapping, which is about as subtle as a foghorn. Another admitted they had “vastly different expectations,” while someone else declared the creator was “doing the lord’s work.” In other words, the tech was real, but the comments were absolutely running on meme fuel. Even the wholesome suggestion to use it for soft sea creatures felt like the thread trying, very briefly, to behave itself.
Key Points
- •The article defines a simple jiggle physics standard based on two components: UV-painted weight maps and damped spring bones.
- •The core deformation rule is `vertex += weight * boneJiggle`, with the demo using an equivalent offset sampling method in an SDF ray-marcher.
- •The simulation engine in `jiggle-physics.js` is renderer-agnostic and has no DOM or WebGL dependency, while `jiggle-app.js` provides a WebGL demo renderer.
- •Each jiggle bone is driven by parent acceleration impulses and velocity-based lag, with randomized stiffness, damping, coupling, and gravity sag.
- •The reference scene includes five test geometries, UV-based weight painting, heatmaps, physics controls, and preset weight maps stored in a `512×256` RGBA texture.