gltfjsx-preview.mp4

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

The GLTF workflow on the web is not ideal ...

• GLTF is thrown whole 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 is cumbersome
• Model compression is complex and not easily achieved
• Models often have unnecessary nodes that cause extra work and matrix updates

GLTFJSX fixes that

• 🧑‍💻 It creates a virtual graph of all objects and materials. Now you can easily alter contents and re-use.
• 🏎️ The graph gets pruned (empty groups, unnecessary transforms, ...) and will perform better.
• ⚡️ It will optionally compress your model with up to 70%-90% size reduction.

Usage

Usage
  $ npx gltfjsx [Model.glb] [options]

Options
  --output, -o        Output file name/path
  --types, -t         Add Typescript definitions
  --keepnames, -k     Keep original names
  --keepgroups, -K    Keep (empty) groups, disable pruning
  --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: 3)
  --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)
    --resolution, -R  Resolution for texture resizing (default: 1024)
    --keepmeshes, -j  Do not join compatible meshes
    --keepmaterials, -M Do not palette join materials
    --format, -f      Texture format (default: "webp")
    --simplify, -S    Mesh simplification (default: false)
      --weld          Weld tolerance (default: 0.00005)
      --ratio         Simplifier ratio (default: 0)
      --error         Simplifier error threshold (default: 0.0001)
  --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 --transform

This will create a Model.jsx file that plots out all of the assets contents.

/*
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-transformed.glb')
  return (
    <group {...props} dispose={null}>
      <PerspectiveCamera name="camera" fov={40} near={10} far={1000} position={[10, 0, 50]} />      
      <pointLight intensity={10} position={[100, 50, 100]} rotation={[-Math.PI / 2, 0, 0]} />
      <group position={[10, -5, 0]}>
        <mesh geometry={nodes.robot.geometry} material={materials.metal} />
        <mesh geometry={nodes.rocket.geometry} material={materials.wood} />
      </group>
    </group>
  )
}

useGLTF.preload('/model.gltf')

Add your model to your /public folder as you would normally do. With the --transform flag it has created a compressed copy of it (in the above case model-transformed.glb). Without the flag just copy the original model.

/public
  model-transformed.glb

The component can now be dropped into your scene.

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

function App() {
  return (
    <Canvas>
      <Model />      

You can re-use it, it will re-use geometries and materials out of the box:

<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.

⚡️ 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')

⚡️ Auto-transform (compression, resize)

With the --transform flag it creates a binary-packed, draco-compressed, texture-resized (1024x1024), webp compressed, deduped, instanced and pruned *.glb ready to be consumed on a web site. It uses glTF-Transform. This can reduce the size of an asset by 70%-90%.

It will not alter the original but create a copy and append [modelname]-transformed.glb.

⚡️ 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')

⚡️ 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])

⚡️ 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 '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(gltf, optionalConfig)
})

Using the parser stand-alone for scenes (object3d's)

const jsx = parse(scene, optionalConfig)

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 'gltfjsx'
import fs from 'fs/promises'

it('should have a scene with a blue mesh', async () => {
  const loader = new GLTFStructureLoader()
  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 (>= 122.x)
• @react-three/fiber (>= 5.x)
• @react-three/drei (>= 2.x)