🐲 minidraco

A fast, pure-TypeScript Draco mesh decoder with a drop-in DRACOLoader for Three.js — no wasm to host or fetch, and a worker pool so decoding never blocks the main thread.

Usage

import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js'
import { MinidracoLoader } from 'minidraco/three'

const gltfLoader = new GLTFLoader()
gltfLoader.setDRACOLoader(new MinidracoLoader())
gltfLoader.load('model.glb', gltf => scene.add(gltf.scene))

A drop-in for THREE.DRACOLoader, no cast needed. Decoding runs in a worker pool by default, with a main-thread fallback. Options:

new MinidracoLoader({ workers: false }) // decode on the main thread
new MinidracoLoader({ workerLimit: 8 }) // pool size (default 4)

Or decode a raw bitstream without Three.js:

import { decodeDracoMesh } from 'minidraco'

const mesh = decodeDracoMesh(new Uint8Array(bytes))

Features

• Every Draco triangle mesh — all encodings, prediction schemes, and attribute types.
• Bit-identical to the official wasm decoder, verified in the tests.
• No point clouds (glTF Draco is always meshes).

Performance

Median across a 19-model corpus vs draco.js and the official draco3d wasm decoder (full results in BENCH.md):

| benchmark | vs draco.js | vs draco3d wasm | | --------------------------------------------- | --------------- | --------------- | | single-threaded decode — bun (JSC) | ⚪ even | 🟢 1.13× faster | | single-threaded decode — Chrome (V8) | ⚪ even | 🟢 1.50× faster | | GLTFLoader.parse, worker pool — Chrome (V8) | 🟢 1.23× faster | 🔴 1.10× slower |

On par with draco.js, faster than the wasm decoder single-threaded, and competitive in a real GLTFLoader.parse with the main thread left free.

🟢 Cold start is the real win, and no warm benchmark shows it: there's no draco_decoder.wasm to fetch and compile before the first decode, so the first model on screen appears sooner.

Download size

Over the wire (brotli): ~23 KB ships in your app bundle. With the worker pool on (default) the browser also fetches a ~22 KB worker chunk on the first decode — ~45 KB total; workers: false skips that fetch. draco.js ~22 KB, draco3d wasm ~76 KB — the wasm is a separate file you must host, while the JS decoders ship inside your bundle.

Monorepo

• library/ — the minidraco package
• example/ — Next.js + React Three Fiber demo with an in-browser benchmark at /bench

bun install
bun dev        # watch build + demo
bun run all    # format, lint, typecheck, tests
bun run bench  # cross-decoder benchmark

License

MIT — derived from mrdoob/draco.js (MIT), implementing Google's Draco bitstream (Apache-2.0).