How do I import code from THREE.js examples? - three.js

Question

I am currently building a React application that utilizes THREE.js.
I want to import some code from THREE.js library, which is not part of the official distribution. Under the official repo for THREE.js, there are some modules under the examples folder, which the official doc for THREE.js makes use of to showcase examples.
How can I make use of these modules and use them in my own code?
In my app, I wanted to use the THREE.STLExporter module.
(https://github.com/mrdoob/three.js/blob/master/examples/js/exporters/STLExporter.js)
Because I already installed three as a dependency for my app, I first tried simply doing import * as THREE from 'three', which did not seem to do the trick.
Then I tried to access the examples folder directly and grab the module manually by doing `require('three/examples/js/exporters/STLExporter'), but this did not work either.
I have checked the source code for the official docs and noticed that the examples directly include the necessary modules in tags, but I don't want to do that because I am building a React app. I want to be able to include modules either via NPM or storing the code for the module within my app.
Please help out a noob here. Thank you!

Answer 1

You can create a separate three.js file that will import "three", add any examples code to it and export as an object, here is a snippet that works with THREE.OrbitControls:
import * as THREE from 'three';
window.THREE = THREE; // THREE.OrbitControls expects THREE to be a global object
require('three/examples/js/controls/OrbitControls');
export default window.THREE;
Then use three.js file in your app like this:
import React, { Component } from "react";
import ReactDOM from "react-dom";
import THREE from "./three";
class App extends Component {
componentDidMount() {
// BASIC THREE.JS THINGS: SCENE, CAMERA, RENDERER
// Three.js Creating a scene tutorial
// https://threejs.org/docs/index.html#manual/en/introduction/Creating-a-scene
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(
75,
window.innerWidth / window.innerHeight,
0.1,
1000
);
camera.position.z = 5;
var renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
// MOUNT INSIDE OF REACT
this.mount.appendChild(renderer.domElement); // mount a scene inside of React using a ref
// CAMERA CONTROLS
// https://threejs.org/docs/index.html#examples/controls/OrbitControls
this.controls = new THREE.OrbitControls(camera);
// ADD CUBE AND LIGHTS
// https://threejs.org/docs/index.html#api/en/geometries/BoxGeometry
// https://threejs.org/docs/scenes/geometry-browser.html#BoxGeometry
var geometry = new THREE.BoxGeometry(2, 2, 2);
var material = new THREE.MeshPhongMaterial( {
color: 0x156289,
emissive: 0x072534,
side: THREE.DoubleSide,
flatShading: true
} );
var cube = new THREE.Mesh(geometry, material);
scene.add(cube);
var lights = [];
lights[ 0 ] = new THREE.PointLight( 0xffffff, 1, 0 );
lights[ 1 ] = new THREE.PointLight( 0xffffff, 1, 0 );
lights[ 2 ] = new THREE.PointLight( 0xffffff, 1, 0 );
lights[ 0 ].position.set( 0, 200, 0 );
lights[ 1 ].position.set( 100, 200, 100 );
lights[ 2 ].position.set( - 100, - 200, - 100 );
scene.add( lights[ 0 ] );
scene.add( lights[ 1 ] );
scene.add( lights[ 2 ] );
// SCALE ON RESIZE
// Check "How can scene scale be preserved on resize?" section of Three.js FAQ
// https://threejs.org/docs/index.html#manual/en/introduction/FAQ
// code below is taken from Three.js fiddle
// http://jsfiddle.net/Q4Jpu/
// remember these initial values
var tanFOV = Math.tan( ( ( Math.PI / 180 ) * camera.fov / 2 ) );
var windowHeight = window.innerHeight;
window.addEventListener( 'resize', onWindowResize, false );
function onWindowResize( event ) {
camera.aspect = window.innerWidth / window.innerHeight;
// adjust the FOV
camera.fov = ( 360 / Math.PI ) * Math.atan( tanFOV * ( window.innerHeight / windowHeight ) );
camera.updateProjectionMatrix();
camera.lookAt( scene.position );
renderer.setSize( window.innerWidth, window.innerHeight );
renderer.render( scene, camera );
}
// ANIMATE THE SCENE
var animate = function() {
requestAnimationFrame(animate);
cube.rotation.x += 0.01;
cube.rotation.y += 0.01;
renderer.render(scene, camera);
};
animate();
}
render() {
return <div ref={ref => (this.mount = ref)} />;
}
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
working demo on stackblitz https://stackblitz.com/edit/react-three-example-import?file=index.js

Answer 2

You should import the full path of the module:
import { STLExporter } as THREE from 'three/examples/jsm/STLExporter