threejs-scene-setup

SKILL.md

three.js Scene Setup

Create the foundation of a three.js app: module loading, the
scene/camera/renderer trio, the render loop, responsive resizing, and camera
controls. Patterns target r186. Read the installed three version before
changing an existing project because examples and addons move across releases.

When to use

Use when bootstrapping a three.js scene, fixing a blank/black canvas, making the
canvas responsive, setting up the animation loop, or adding OrbitControls.

Use when package.json depends on three and code does import * as THREE from 'three'.

When not to use: loading .gltf/.glb models or skinned animation →
threejs-gltf-loading. Materials, lights, shadows, environment maps →
threejs-materials-lighting. 2D rendering → pixijs-rendering.

Core workflow

Load three.js as an ES module with an import map. Since r147 the bare
specifier 'three' and 'three/addons/' must be mapped (in HTML or by a
bundler). Addons (controls, loaders) live under three/addons/....

Create the trio. A Scene (root of the graph), a PerspectiveCamera(fov, aspect, near, far) moved back from the origin, and a WebGLRenderer whose
domElement is in the DOM. Set size and pixelRatio.

Add a mesh. new Mesh(geometry, material) and scene.add(mesh). With a
lit material you also need a light (see threejs-materials-lighting).

Drive a render loop with renderer.setAnimationLoop(fn). It's the modern,
WebXR-/WebGPU-safe replacement for hand-rolled requestAnimationFrame. Use a
Timer for delta time (Clock is deprecated since r183).

Handle resize so the camera aspect and renderer match the canvas; update
camera.aspect, call updateProjectionMatrix(), and renderer.setSize(...).

Add OrbitControls for orbit/pan/zoom while developing. Confirm something
actually renders (a lit cube, the controls responding) before assuming success.

Patterns

1. HTML import map + module entry (no bundler)

<canvas id="c"></canvas>
<script type="importmap">
{
  "imports": {
    "three": "https://cdn.jsdelivr.net/npm/three@0.186.0/build/three.module.js",
    "three/addons/": "https://cdn.jsdelivr.net/npm/three@0.186.0/examples/jsm/"
  }
}
</script>
<script type="module" src="./main.js"></script>

With a bundler (Vite/webpack), skip the import map and just
npm i three; the same import statements resolve.

2. Scene + camera + renderer

// main.js
import * as THREE from 'three';

const canvas = document.querySelector('#c');
const renderer = new THREE.WebGLRenderer({ canvas, antialias: true });
renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2)); // cap for perf
renderer.setSize(window.innerWidth, window.innerHeight);

const scene = new THREE.Scene();
scene.background = new THREE.Color(0x101018);

const camera = new THREE.PerspectiveCamera(
  60,                                   // vertical field of view (degrees)
  window.innerWidth / window.innerHeight, // aspect
  0.1,                                  // near
  100                                   // far
);
camera.position.set(3, 2, 5);
camera.lookAt(0, 0, 0);

const cube = new THREE.Mesh(
  new THREE.BoxGeometry(1, 1, 1),
  new THREE.MeshNormalMaterial()        // unlit; shows orientation without a light
);
scene.add(cube);

3. The render loop (setAnimationLoop + Timer)

const timer = new THREE.Timer();        // replaces the deprecated THREE.Clock (r183+)
timer.connect(document);                // optional: no huge delta after a hidden tab

renderer.setAnimationLoop((time) => {
  timer.update(time);                   // call once per frame, before getDelta()
  const dt = timer.getDelta();          // seconds since last frame
  cube.rotation.x += dt;                // frame-rate independent
  cube.rotation.y += dt * 0.7;
  renderer.render(scene, camera);
});
// renderer.setAnimationLoop(null); // stop the loop

4. Responsive resize

function onResize() {
  const w = window.innerWidth, h = window.innerHeight;
  camera.aspect = w / h;
  camera.updateProjectionMatrix();      // required after changing aspect
  renderer.setSize(w, h);
}
window.addEventListener('resize', onResize);

5. OrbitControls (orbit / pan / zoom)

import { OrbitControls } from 'three/addons/controls/OrbitControls.js';

const controls = new OrbitControls(camera, renderer.domElement);
controls.enableDamping = true;          // inertial feel
controls.target.set(0, 0, 0);

renderer.setAnimationLoop(() => {
  controls.update();                    // needed every frame when damping is on
  renderer.render(scene, camera);
});

Pitfalls

Failed to resolve module specifier "three" → missing import map (or bundler
config). Map both "three" and "three/addons/"; addon paths must end with /.

Black canvas, no errors → camera is at the origin (inside/behind the object),
or you used a lit material (MeshStandardMaterial) with no light. Move the camera
back; use MeshNormalMaterial/MeshBasicMaterial to verify geometry first.

Nothing animates → you never called renderer.render inside the loop, or you
call setAnimationLoop but render outside it.

Stretched / squashed view on resize → you resized the renderer but didn't
update camera.aspect + updateProjectionMatrix().

Blurry or jagged on HiDPI → set renderer.setPixelRatio(...); cap it (≈2) so
4K/retina screens don't tank performance.

OrbitControls feel dead → with enableDamping = true you must call
controls.update() every frame.

Old tutorials use <script src="three.min.js"> → since r147 three.js ships
ES modules only; use type="module" + import maps.

References

For coordinate conventions, the scene-graph (Group, parent/child transforms,
Object3D add/remove), OrthographicCamera for 2.5D, and disposing of
geometries/materials/textures to avoid leaks, read references/scene-graph.md.

Related skills

threejs-materials-lighting — give surfaces a lit look (lights, shadows, PBR).

threejs-gltf-loading — load 3D models and play their animations.

pixijs-rendering — 2D rendering in the browser.

fps-shooter — a 3D genre template that composes three.js skills.