# Harry-babylon: springy tails, bouncy hair and soft-tissue jiggle for Babylon.js avatars (MIT, npm, live demo)

**URL:** <https://forum.babylonjs.com/t/harry-babylon-springy-tails-bouncy-hair-and-soft-tissue-jiggle-for-babylon-js-avatars-mit-npm-live-demo/64238>\
**Category:** Demos and projects\
**Tags:** animation, gltf, tool-chain\
**Created:** [October 5, 2026, 10:31pm UTC](https://forum.babylonjs.com/t/harry-babylon-springy-tails-bouncy-hair-and-soft-tissue-jiggle-for-babylon-js-avatars-mit-npm-live-demo/64238 "2026-10-05T22:31:01Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![increasinglyHuman](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/increasinglyhuman/32/51340_2.png) [@increasinglyHuman](https://forum.babylonjs.com/u/increasinglyHuman)\
**Post date:** [October 5, 2026, 10:31pm UTC](https://forum.babylonjs.com/t/harry-babylon-springy-tails-bouncy-hair-and-soft-tissue-jiggle-for-babylon-js-avatars-mit-npm-live-demo/64238/1 "2026-10-05T22:31:01Z")

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![image_1 - 2026-10-05T114609.372](https://us1.discourse-cdn.com/flex024/uploads/babylonjs/original/3X/6/3/6311c32538f05a5892550bd11ba34133de567aa5.jpeg)

Hi all! [A while back](https://forum.babylonjs.com/t/sharing-my-gltf-animation-pipeline-tool-for-retargeting/64227) I promised a Babylon runtime for avatars finished in Harry, our avatar-finishing tool. It’s out, it’s MIT, and it’s the same code poqpoq World runs.

**Live demo:** [harry-babylon demo](https://increasinglyhuman.github.io/harry-babylon/)  
A Tripo lemur warrior finished in Harry: wagging tail, bouncing ears, a walk, a hop and a deep squat that shows off the creases. Hit _Spawn crowd_ for 20 more under a physics budget.

**Try it in the Playground:** [Babylon.js Playground](https://playground.babylonjs.com/#6NLVHQ)

**Install:** `npm i @poqpoq/harry-babylon` (Babylon 9.29+ as a peer dependency)  
**Repo:** [GitHub - increasinglyHuman/harry-babylon: Babylon.js runtime for avatars finished in Harry: tail, hair and soft-tissue springs (VRMC\_springBone), surface jiggle, tail moods and clip binding. MIT. · GitHub](https://github.com/increasinglyHuman/harry-babylon)

**What it does:** [Harry](https://poqpoq.com/harry/) writes an avatar’s runtime behaviour into the GLB itself, and this library reads it back:

- **Spring bones** for tails, hair and soft tissue, from the standard `VRMC_springBone` 1.0 extension, so any VRM-aware tool can read them too.
- **Tail moods** (wag, lash, tuck, twitch, loose…) on top of the springs.
- **Surface jiggle:** modal bounce for breasts, belly, glutes and hair that rides on the skinned mesh.
- **Clip binding** that keeps clavicles anchored to the rest pose, plus hip-height compensation when a clip was authored on a different body.
- **VRoid fallback:** synthesized springs for VRoid bodies that carry none.
- **Crowd-friendly:** distance LOD, off-screen pausing and a shared per-scene budget.

One call wires it up:

```js
import { ImportMeshAsync } from '@babylonjs/core'
import { attachHarryPhysics } from '@poqpoq/harry-babylon'

const result = await ImportMeshAsync('avatar.glb', scene)
const physics = attachHarryPhysics(result.meshes[0], scene, result.meshes)
physics.springs?.setMood('wag')

```

Everything except the springs is plain glTF (armature, skin weights, corrective bones, morphs), so it works in any engine. The springs and jiggle are the parts that need a runtime, and this is that runtime for Babylon.

Feedback, issues and PRs are very welcome. And if you’d like to see these avatars in a live world, poqpoq World is looking for alpha testers: [pOqpOq World - A Social Adventure You Build Together | BlackBox Creative Suite](https://poqpoq.com/world/)

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**Author:** ![AlitarSemiramis](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/alitarsemiramis/32/49920_2.png) [@AlitarSemiramis](https://forum.babylonjs.com/u/AlitarSemiramis)\
**Post date:** [October 6, 2026, 12:23am UTC](https://forum.babylonjs.com/t/harry-babylon-springy-tails-bouncy-hair-and-soft-tissue-jiggle-for-babylon-js-avatars-mit-npm-live-demo/64238/2 "2026-10-06T00:23:04Z")

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The playground looks super good!