Draco3D — 3D Geometry Compression

Google Draco 3D geometry compression library. Compresses and decompresses 3D meshes and point clouds, with glTF, Three.js, and Unity integration.

npm i draco3d (WASM codec) | CDN: gstatic.com/draco/versioned/decoders/1.5.7/

Use Cases

Use when compressing 3D models, decoding Draco files, integrating Draco in web projects, using the draco3d npm package, or handling glTF Draco extensions.

Decoding

js

import DracoDecoderModule from 'draco3d/draco_decoder.js';
const d = await DracoDecoderModule();

const buf = new d.DecoderBuffer();
buf.Init(bytes, bytes.length);
const dec = new d.Decoder();
const type = dec.GetEncodedGeometryType(buf);

const geo = type === d.TRIANGULAR_MESH ? new d.Mesh() : new d.PointCloud();
type === d.TRIANGULAR_MESH
  ? dec.DecodeBufferToMesh(buf, geo)
  : dec.DecodeBufferToPointCloud(buf, geo);

// Read positions
const a = dec.GetAttribute(geo, d.POSITION);
const fa = new d.DracoFloat32Array();
dec.GetAttributeFloatForAllPoints(geo, a, fa);

// Read face indices (mesh only)
const ia = new d.DracoInt32Array();
for (let i = 0; i < geo.num_faces(); i++) {
  dec.GetFaceFromMesh(geo, i, ia); // ia.GetValue(0/1/2)
}

// ⚠️ Must manually release
d.destroy(geo); d.destroy(dec); d.destroy(buf); d.destroy(fa);

Encoding

js

import DracoEncoderModule from 'draco3d/draco_encoder.js';
const d = await DracoEncoderModule();

const mesh = new d.Mesh();
const b = new d.MeshBuilder();
b.AddFacesToMesh(mesh, numFaces, indices);
b.AddFloatAttributeToMesh(mesh, d.POSITION, numVerts, 3, positions);
b.AddFloatAttributeToMesh(mesh, d.NORMAL, numVerts, 3, normals);

const enc = new d.Encoder();
enc.SetEncodingMethod(d.MESH_EDGEBREAKER_ENCODING);
enc.SetAttributeQuantization(d.POSITION, 11);

const out = new d.DracoInt8Array();
enc.EncodeMeshToDracoBuffer(mesh, out);
d.destroy(mesh); d.destroy(enc); d.destroy(b);

Three.js

js

import { DRACOLoader } from 'three/examples/jsm/loaders/DRACOLoader.js';
const loader = new DRACOLoader();
loader.setDecoderPath('https://www.gstatic.com/draco/versioned/decoders/1.5.7/');
gltfLoader.setDRACOLoader(loader);

Attribute Constants & Quantization Defaults

Constant	Quant. Bits	Range
POSITION	11	8–14
NORMAL	7	6–10
TEX_COORD	10	8–12
COLOR	8	6–10
GENERIC	8	—

Encoding methods: MESH_EDGEBREAKER_ENCODING (high compression, default) | MESH_SEQUENTIAL_ENCODING (faster decode)

Key Notes

• Module returns a Promise — must await
• All WASM objects must be released via d.destroy(obj), otherwise memory leaks
• Production: lock CDN version, avoid the unversioned /v1/decoders/ path

Detailed API

references/api-reference.md — Decoder/Encoder/MeshBuilder full method signatures, Metadata, ExpertEncoder, Node.js.