Welcome to Expo & Three.JS 👋

Tools for using three.js to create universal 3D experiences | Try it in the browser!

AR was moved to expo-three-ar in expo-three@5.0.0

Installation

In expo-three@5.0.0 Three.js is a peer dependency

yarn add three expo-three

Usage

Import the library into your JavaScript file:

import ExpoTHREE from 'expo-three';

Get a global instance of three.js from expo-three:

import { THREE } from 'expo-three';

Due to some issues with the Metro bundler you may need to manually define the global instance of Three.js. This is important because three.js doesn't fully use ECMAScript but rather mutates a single global instance of THREE with side-effects.

global.THREE = global.THREE || THREE;

Creating a Renderer

ExpoTHREE.Renderer({ gl: WebGLRenderingContext, width: number, height: number, pixelRatio: number, ...extras })

Given a gl from an Expo.GLView, return a THREE.WebGLRenderer that draws into it.

const renderer = new ExpoTHREE.Renderer(props);
or;
/// A legacy alias for the extended renderer
const renderer = ExpoTHREE.createRenderer(props);
// Now just code some three.js stuff and add it to this! :D

ExpoTHREE.loadAsync()

A function that will asynchronously load files based on their extension.

Notice: Remember to update your app.json to bundle obscure file types!

app.json

{
  "expo": {
    "packagerOpts": {
+      "config": "metro.config.js"
    },
  }
}

metro.config.js

module.exports = {
  resolver: {
    assetExts: ['db', 'mp3', 'ttf', 'obj', 'png', 'jpg'],
  },
};

Props

Property	Type	Description
resource	PossibleAsset	The asset that will be parsed asynchornously
onProgress	(xhr) => void	A function that is called with an xhr event
assetProvider	() => Promise<Expo.Asset>	A function that is called whenever an unknown asset is requested

PossibleAsset Format

export type PossibleAsset = Expo.Asset | number | string | AssetFormat;

type PossibleAsset = number | string | Expo.Asset;

• number: Static file reference require('./model.*')
• Expo.Asset: Expo.Asset
• string: A uri path to an asset

Returns

This returns many different things, based on the input file. For a more predictable return value you should use one of the more specific model loaders.

Example

const texture = await ExpoTHREE.loadAsync(
  'https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png',
);

Loaders

loadAsync(assetReference, onProgress, onAssetRequested)

A universal loader that can be used to load images, models, scenes, and animations. Optionally more specific loaders are provided with less complexity.

// A THREE.Texture from a static resource.
const texture = await ExpoTHREE.loadAsync(require('./icon.png'));
const obj = await ExpoTHREE.loadAsync(
  [require('./cartman.obj'), require('./cartman.mtl')],
  null,
  imageName => resources[imageName],
);
const { scene } = await ExpoTHREE.loadAsync(
  resources['./kenny.dae'],
  onProgress,
  resources,
);

loadObjAsync({ asset, mtlAsset, materials, onAssetRequested, onMtlAssetRequested })

Props

• asset: a obj model reference that will be evaluated using AssetUtils.uriAsync
• mtlAsset: an optional prop that will be loaded using loadMtlAsync()
• onAssetRequested: A callback that is used to evaluate urls found within the asset and optionally the mtlAsset. You can also just pass in a dictionary of key values if you know the assets required ahead of time.
• materials: Optionally you can provide an array of materials returned from loadMtlAsync()
• onMtlAssetRequested: If provided this will be used to request assets in loadMtlAsync()

This function is used as a more direct method to loading a .obj model. You should use this function to debug when your model has a corrupted format.

const mesh = await loadObjAsync({ asset: 'https://www.members.com/chef.obj' });

loadTextureAsync({ asset })

Props

• asset: an Expo.Asset that could be evaluated using AssetUtils.resolveAsync if localUri is missing or the asset hasn't been downloaded yet.

This function is used as a more direct method to loading an image into a texture. You should use this function to debug when your image is using an odd extension like .bmp.

const texture = await loadTextureAsync({ asset: require('./image.png') });

loadMtlAsync({ asset, onAssetRequested })

Props

• asset: a mtl material reference that will be evaluated using AssetUtils.uriAsync
• onAssetRequested: A callback that is used to evaluate urls found within the asset, optionally you can just pass in a dictionary of key values if you know the assets required ahead of time.

const materials = await loadMtlAsync({
  asset: require('chef.mtl'),
  onAssetRequested: modelAssets,
});

loadDaeAsync({ asset, onAssetRequested, onProgress })

Props

• asset: a reference to a dae scene that will be evaluated using AssetUtils.uriAsync
• onAssetRequested: A callback that is used to evaluate urls found within the asset, optionally you can just pass in a dictionary of key values if you know the assets required ahead of time.
• onProgress: An experimental callback used to track loading progress.

const { scene } = await loadDaeAsync({
  asset: require('chef.dae'),
  onAssetRequested: modelAssets,
  onProgress: () => {},
});

---

ExpoTHREE.utils

ExpoTHREE.utils.alignMesh()

Props

type Axis = {
  x?: number,
  y?: number,
  z?: number,
};

Property	Type	Description
mesh	&THREE.Mesh	The mesh that will be manipulated
axis	?Axis	Set the relative center axis

Example

ExpoTHREE.utils.alignMesh(mesh, { x: 0.0, y: 0.5 });

---

ExpoTHREE.utils.scaleLongestSideToSize()

Props

Property	Type	Description
mesh	&THREE.Mesh	The mesh that will be manipulated
size	number	The size that the longest side of the mesh will be scaled to

Example

ExpoTHREE.utils.scaleLongestSideToSize(mesh, 3.2);

---

ExpoTHREE.utils.computeMeshNormals()

Used for smoothing imported geometry, specifically when imported from .obj models.

Props

Property	Type	Description
mesh	&THREE.Mesh	The mutable (inout) mesh that will be manipulated

Example

ExpoTHREE.utils.computeMeshNormals(mesh);
```

---

## THREE Extensions

### `suppressExpoWarnings`

A function that suppresses EXGL compatibility warnings and logs them instead.
You will need to import the `ExpoTHREE.THREE` global instance to use this. By
default this function will be activated on import.

* `shouldSuppress`: boolean

```js
import { THREE } from 'expo-three';
THREE.suppressExpoWarnings();

---

⛓ Links

Somewhat out of date

• Loading Text

• three.js docs

• Random Demos

• Game: Expo Sunset Cyberspace

• Game: Crossy Road

• Game: Nitro Roll

• Game: Pillar Valley

• Voxel Terrain

🤝 Contributing

Contributions, issues and feature requests are welcome!
Feel free to check issues page.

Show your support

Give a ⭐️ if this project helped you!

📝 License

Copyright © 2019 650 Industries.
This project is MIT licensed.