Three.js Skills

Systematically create high-quality 3D scenes and interactive experiences using Three.js best practices.

When to Use

• Requests 3D visualizations or graphics ("create a 3D model", "show in 3D")
• Wants interactive 3D experiences ("rotating cube", "explorable scene")
• Needs WebGL or canvas-based rendering
• Asks for animations, particles, or visual effects
• Mentions Three.js, WebGL, or 3D rendering
• Wants to visualize data in 3D space

Core Setup Pattern

1. Essential Three.js Imports

Use ES module import maps for modern Three.js (r183+):

<script type="importmap">
{
  "imports": {
    "three": "https://cdn.jsdelivr.net/npm/[email protected]/build/three.module.js",
    "three/addons/": "https://cdn.jsdelivr.net/npm/[email protected]/examples/jsm/"
  }
}
</script>
<script type="module">
import * as THREE from "three";
import { OrbitControls } from "three/addons/controls/OrbitControls.js";
</script>

For production with npm/vite/webpack:

import * as THREE from "three";
import { OrbitControls } from "three/addons/controls/OrbitControls.js";

2. Scene Initialization

Every Three.js artifact needs these core components:

// Scene - contains all 3D objects
const scene = new THREE.Scene();

// Camera - defines viewing perspective
const camera = new THREE.PerspectiveCamera(
  75, // Field of view
  window.innerWidth / window.innerHeight, // Aspect ratio
  0.1, // Near clipping plane
  1000, // Far clipping plane
);
camera.position.z = 5;

// Renderer - draws the scene
const renderer = new THREE.WebGLRenderer({ antialias: true });
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);

3. Animation Loop

Use renderer.setAnimationLoop() (preferred) or requestAnimationFrame:

// Preferred: setAnimationLoop (handles WebXR compatibility)
renderer.setAnimationLoop(() => {
  mesh.rotation.x += 0.01;
  mesh.rotation.y += 0.01;
  renderer.render(scene, camera);
});

// Alternative: manual requestAnimationFrame
function animate() {
  requestAnimationFrame(animate);
  mesh.rotation.x += 0.01;
  mesh.rotation.y += 0.01;
  renderer.render(scene, camera);
}
animate();

Systematic Development Process

1. Define the Scene

Start by identifying:

• What objects need to be rendered
• Camera position and field of view
• Lighting setup required
• Interaction model (static, rotating, user-controlled)

2. Build Geometry

Choose appropriate geometry types:

Basic Shapes:

• BoxGeometry - cubes, rectangular prisms
• SphereGeometry - spheres, planets
• CylinderGeometry - cylinders, tubes
• PlaneGeometry - flat surfaces, ground planes
• TorusGeometry - donuts, rings

CapsuleGeometry is available (stable since r142):

new THREE.CapsuleGeometry(0.5, 1, 4, 8); // radius, length, capSegments, radialSegments

3. Apply Materials

Choose materials based on visual needs:

Common Materials:

• MeshBasicMaterial - unlit, flat colors (no lighting needed)
• MeshStandardMaterial - physically-based, realistic (needs lighting)
• MeshPhongMaterial - shiny surfaces with specular highlights
• MeshLambertMaterial - matte surfaces, diffuse reflection

const material = new THREE.MeshStandardMaterial({
  color: 0x00ff00,
  metalness: 0.5,
  roughness: 0.5,
});

4. Add Lighting

If using lit materials (Standard, Phong, Lambert), add lights:

// Ambient light - general illumination
const ambientLight = new THREE.AmbientLight(0xffffff, 0.5);
scene.add(ambientLight);

// Directional light - like sunlight
const directionalLight = new THREE.DirectionalLight(0xffffff, 0.8);
directionalLight.position.set(5, 5, 5);
scene.add(directionalLight);

Skip lighting if using MeshBasicMaterial - it's unlit by design.

5. Handle Responsiveness

Always add window resize handling:

window.addEventListener("resize", () => {
  camera.aspect = window.innerWidth / window.innerHeight;
  camera.updateProjectionMatrix();
  renderer.setSize(window.innerWidth, window.innerHeight);
});

Common Patterns

Rotating Object

function animate() {
  requestAnimationFrame(animate);
  mesh.rotation.x += 0.01;
  mesh.rotation.y += 0.01;
  renderer.render(scene, camera);
}

OrbitControls

With import maps or build tools, OrbitControls works directly:

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

const controls = new OrbitControls(camera, renderer.domElement);
controls.enableDamping = true;

// Update in animation loop
renderer.setAnimationLoop(() => {
  controls.update();
  renderer.render(scene, camera);
});

Custom Camera Controls (Alternative)

For lightweight custom controls without importing OrbitControls:

```javascript let isDragging = false; let previousMousePosition = { x: 0, y: 0 };

renderer.domElement.addEventList