expo-three

Tools for using three.js to build native 3D experiences 💙

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';

Do 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

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,
};

Example

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

ExpoTHREE.utils.scaleLongestSideToSize()

Props

Example

ExpoTHREE.utils.scaleLongestSideToSize(mesh, 3.2);

ExpoTHREE.utils.computeMeshNormals()

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

Props

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