gltfjsx-preview.mp4

A small command-line tool that turns GLTF assets into declarative and re-usable react-three-fiber JSX components.

Why? Because the GLTF workflow on the web is not ideal ...

• GLTF is thrown wholesale into the scene which prevents re-use, in threejs objects can only be mounted once
• Contents can only be found by traversal which is cumbersome and slow
• Changes to queried nodes are made by mutation, which alters the source data and prevents re-use
• Re-structuring content, making nodes conditional or adding/removing thems is cumbersome

Gltfjsx creates a virtual, nested graph of all the objects and materials inside your asset. It will not touch or modify your files in any way. Now you can easily make the data dynamic, alter contents, add events, or re-use the asset without having to re-parse and clone, as it is usually done.

Usage

Usage
  $ npx gltfjsx model.gltf [options]

Options
  --types, -t         Add Typescript definitions
  --keepnames, -k     Keep original names
  --keepgroups, -K    Keep (empty) groups
  --meta, -m          Include metadata (as userData)
  --shadows, s        Let meshes cast and receive shadows
  --printwidth, w     Prettier printWidth (default: 120)
  --precision, -p     Number of fractional digits (default: 2)
  --draco, -d         Draco binary path
  --root, -r          Sets directory from which .gltf file is served
  --instance, -i      Instance re-occuring geometry
  --instanceall, -I   Instance every geometry (for cheaper re-use)
  --transform, -T     Transform the asset for the web (draco, prune, resize)
  --aggressive, -a    Aggressively prune the graph (empty groups, transform overlap)
  --debug, -D         Debug output

A typical use-case

First you run your model through gltfjsx. npx allows you to use npm packages without installing them.

npx gltfjsx model.gltf

It creates a javascript file that plots out all of the assets contents. The original gltf must still be be in your /public folder of course.

/*
auto-generated by: https://github.com/pmdrs/gltfjsx
author: abcdef (https://sketchfab.com/abcdef)
license: CC-BY-4.0 (http://creativecommons.org/licenses/by/4.0/)
source: https://sketchfab.com/models/...
title: Model
*/

import { useGLTF, PerspectiveCamera } from '@react-three/drei'

export function Model(props) {
  const { nodes, materials } = useGLTF('/model.gltf')
  return (
    <group {...props} dispose={null}>
      <group name="camera" position={[10, 0, 50]} rotation={[Math.PI / 2, 0, 0]}>
        <PerspectiveCamera fov={40} near={10} far={1000} />
      </group>
      <group name="sun" position={[100, 50, 100]} rotation={[-Math.PI / 2, 0, 0]}>
        <pointLight intensity={10} />
      </group>
      <mesh geometry={nodes.robot.geometry} material={materials.metal} />
      <mesh geometry={nodes.rocket.geometry} material={materials.wood} />
    </group>
  )
}

useGLTF.preload('/model.gltf')

This component can now be dropped into your scene. It is asynchronous and therefore must be wrapped into <Suspense> which gives you full control over intermediary loading-fallbacks and error handling.

import { Canvas } from '@react-three/fiber'
import { Suspense } from 'react'
import Model from './Model'

function App() {
  return (
    <Canvas>
      <Suspense fallback={null}>
        <Model />
      </Suspense>

Now you could re-use it:

<Model position={[0, 0, 0]} />
<Model position={[10, 0, -10]} />

Or make the model dynamic. Change its colors for example:

<mesh geometry={nodes.robot.geometry} material={materials.metal} material-color="green" />

Or exchange materials:

<mesh geometry={nodes.robot.geometry}>
  <meshPhysicalMaterial color="hotpink" />
</mesh>

Make contents conditional:

{
  condition && <mesh geometry={nodes.robot.geometry} material={materials.metal} />
}

Add events:

<mesh geometry={nodes.robot.geometry} material={materials.metal} onClick={handleClick} />

Features

⚡️ Draco and meshopt compression ootb

You don't need to do anything if your models are draco compressed, since useGLTF defaults to a draco CDN. By adding the --draco flag you can refer to local binaries which must reside in your /public folder.

⚡️ Easier access to animations

If your GLTF contains animations it will add drei's useAnimations hook, which extracts all clips and prepares them as actions:

const { nodes, materials, animations } = useGLTF('/model.gltf')
const { actions } = useAnimations(animations, group)

If you want to play an animation you can do so at any time:

<mesh onClick={(e) => actions.jump.play()} />

If you want to blend animations:

const [name, setName] = useState("jump")
...
useEffect(() => {
  actions[name].reset().fadeIn(0.5).play()
  return () => actions[name].fadeOut(0.5)
}, [name])

⚡️ Preload your assets for faster response

The asset will be preloaded by default, this makes it quicker to load and reduces time-to-paint. Remove the preloader if you don't need it.

useGLTF.preload('/model.gltf')

⚡️ Type-safety

Add the --types flag and your GLTF will be typesafe.

type GLTFResult = GLTF & {
  nodes: { robot: THREE.Mesh; rocket: THREE.Mesh }
  materials: { metal: THREE.MeshStandardMaterial; wood: THREE.MeshStandardMaterial }
}

export default function Model(props: JSX.IntrinsicElements['group']) {
  const { nodes, materials } = useGLTF<GLTFResult>('/model.gltf')

⚡️ Auto-transform (compression, resize)

With the --transform flag it creates a binary-packed, draco-compressed, texture-resized (1024x1024), deduped and pruned GLTF ready to be consumed on a web site. It uses glTF-Transform. It will not alter the original but create a copy and append [modelname]-transformed.glb.

JSX compression is enabled with the --aggressive flag, this will start to cut down on empty or unneccessary groups.

⚡️ Auto-instancing

Use the --instance flag and it will look for similar geometry and create instances of them. Look into drei/Merged to understand how it works. It does not matter if you instanced the model previously in Blender, it creates instances for each mesh that has a specific geometry and/or material.

--instanceall will create instances of all the geometry. This allows you to re-use the model with the smallest amount of drawcalls.

Your export will look like something like this:

const context = createContext()
export function Instances({ children, ...props }) {
  const { nodes } = useGLTF('/model-transformed.glb')
  const instances = useMemo(() => ({ Screw1: nodes['Screw1'], Screw2: nodes['Screw2'] }), [nodes])
  return (
    <Merged meshes={instances} {...props}>
      {(instances) => <context.Provider value={instances} children={children} />}
    </Merged>
  )
}

export function Model(props) {
  const instances = useContext(context)
  return (
    <group {...props} dispose={null}>
      <instances.Screw1 position={[-0.42, 0.04, -0.08]} rotation={[-Math.PI / 2, 0, 0]} />
      <instances.Screw2 position={[-0.42, 0.04, -0.08]} rotation={[-Math.PI / 2, 0, 0]} />
    </group>
  )
}

Note that similar to --transform it also has to transform the model. In order to use and re-use the model import both Instances and Model. Put all your models into the Instances component (you can nest).

The following will show the model three times, but you will only have 2 drawcalls tops.

import { Instances, Model } from './Model'

<Instances>
  <Model position={[10,0,0]}>
  <Model position={[-10,0,0]}>
  <Model position={[-10,10,0]}>
</Instance>

Using the parser stand-alone

import { parse } from '@react-three/gltfjsx'
import { GLTFLoader, DRACOLoader } from 'three-stdlib'

const gltfLoader = new GLTFLoader()
const dracoloader = new DRACOLoader()
dracoloader.setDecoderPath('https://www.gstatic.com/draco/v1/decoders/')
gltfLoader.setDRACOLoader(dracoloader)

gltfLoader.load(url, (gltf) => {
  const jsx = parse(filename, gltf, config)
})

Using GLTFStructureLoader stand-alone

The GLTFStructureLoader can come in handy while testing gltf assets. It allows you to extract the structure without the actual binaries and textures making it possible to run in a testing environment.

import { GLTFStructureLoader } from '@react-three/gltfjsx'
import fs from 'fs/promises'

it('should have a scene with a blue mesh', async () => {
  const data = await fs.readFile('./model.glb')
  const { scene } = await new Promise((res) => loader.parse(data, '', res))
  expect(() => scene.children.length).toEqual(1)
  expect(() => scene.children[0].type).toEqual('mesh')
  expect(() => scene.children[0].material.color).toEqual('blue')
})

Requirements

• Nodejs must be installed
• The GLTF file has to be present in your projects /public folder
• three (>= 121.x)
• @react-three/fiber (>= 5.x)
• @react-three/drei (>= 2.x)