How do I install the Threejs Builder skill?

Run npx skillmds@latest add thedaviddias/threejs-builder in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the Threejs Builder skill do?

Builds simple Three.js web apps with scene setup, lighting, geometry, materials, animation, and responsive rendering. Use when creating or prototyping 3D web scenes with modern Three.js (r150+). It is listed under Coding & Dev Tools on SkillMD.

Is Threejs Builder safe to use?

This skill has not completed SkillMD's automated safety review yet. Capability flags: executes scripts, makes network calls. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Threejs Builder?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Threejs Builder free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Threejs Builder?

thedaviddias (@thedaviddias) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Threejs Builder by thedaviddias — Agent Skill

Name: Threejs Builder
Rating: 4.2 (5 reviews)
Author: thedaviddias

Three.js Builder

A focused skill for creating simple, performant Three.js web applications using modern ES module patterns.

Reference Files

Important: Read the appropriate reference file when working on specific topics.

Topic	File	Use When
GLTF Models	gltf-loading-guide.md	Loading, caching, cloning 3D models, SkeletonUtils
Reference Frames	reference-frame-contract.md	Calibration, anchoring, axis correctness, debugging
Game Development	game-patterns.md	State machines, animation switching, parallax, object pooling
Advanced Topics	advanced-topics.md	Post-processing, shaders, physics, instancing
Calibration Helpers	scripts/README.md	GLTF calibration helper installation and usage

Philosophy: The Scene Graph Mental Model

Three.js is built on the scene graph—a hierarchical tree of objects where parent transformations affect children. Understanding this mental model is key to effective 3D web development.

Before creating a Three.js app, ask:

What is the core visual element? (geometry, shape, model)
What interaction does the user need? (none, orbit controls, custom input)
What performance constraints exist? (mobile, desktop, WebGL capabilities)
What animation brings it to life? (rotation, movement, transitions)

Core principles:

Scene Graph First: Everything added to scene renders. Use Group for hierarchical transforms.
Primitives as Building Blocks: Built-in geometries (Box, Sphere, Torus) cover 80% of simple use cases.
Animation as Transformation: Change position/rotation/scale over time using requestAnimationFrame or renderer.setAnimationLoop.
Performance Through Simplicity: Fewer objects, fewer draw calls, reusable geometries/materials.

Three.js Coordinate System (CRITICAL)

Understanding Three.js's right-handed coordinate system is essential to avoid inverted movement, wrong-facing models, and broken collision detection.

The Axes

      +Y (up)
       |
       |
       |_______ +X (right)
      /
     /
    +Z (toward camera/viewer)

Memory aid: Point your thumb (+X), index finger (+Y), middle finger (+Z) - that's right-handed coordinates.

Axis	Direction	Common Usage
+X	Right	Strafe right, spawn right
-X	Left	Strafe left, spawn left
+Y	Up	Jump, height
-Y	Down	Fall, gravity
+Z	Toward camera	Approach viewer, "forward" in many setups
-Z	Away from camera	Retreat, GLTF models face -Z by default

GLTF Model Default Orientation

CRITICAL: GLTF models exported from Blender/Maya face -Z (into the screen) by default.

// GLTF model faces -Z. To face +Z (toward camera):
model.rotation.y = Math.PI;  // 180° rotation

// To face +X (right):
model.rotation.y = -Math.PI / 2;  // -90°

// To face -X (left):
model.rotation.y = Math.PI / 2;   // +90°

Camera-Relative Movement (CRITICAL for Games)

PROBLEM: When camera is at an angle (e.g., isometric view), raw WASD input moves wrong!

// ❌ WRONG - Input is world-axis relative, not camera-relative
if (keyW) player.position.z -= speed;  // Moves toward -Z, not "forward" from player's view
if (keyD) player.position.x += speed;  // Moves +X, not "right" from camera's view

// ✓ CORRECT - Calculate camera-relative directions
function updateMovement(deltaTime) {
    // Get camera's forward direction, projected onto ground (XZ plane)
    const forward = new THREE.Vector3();
    camera.getWorldDirection(forward);
    forward.y = 0;
    forward.normalize();

    // Calculate right vector (cross product of forward and world up)
    const right = new THREE.Vector3();
    right.crossVectors(forward, new THREE.Vector3(0, 1, 0)).normalize();

    // Apply input relative to camera orientation
    const velocity = new THREE.Vector3();
    if (inputState.up) velocity.add(forward);
    if (inputState.down) velocity.sub(forward);
    if (inputState.right) velocity.add(right);
    if (inputState.left) velocity.sub(right);

    if (velocity.length() > 0) {
        velocity.normalize().multiplyScalar(speed * deltaTime);
        player.position.add(velocity);

        // Face movement direction
        player.rotation.y = Math.atan2(velocity.x, velocity.z);
    }
}

Why this matters: With camera at (8, 11, -6) looking at (0, 1, 3):

"Forward" visually is NOT -Z, it's roughly +Z
"Right" visually is NOT +X, it's roughly -X + Z
Raw axis input feels completely inverted to players

Quick Start: Essential Setup

Minimal HTML Template

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Three.js App</title>
    <style>
        * { margin: 0; padding: 0; box-sizing: border-box; }
        body { overflow: hidden; background: #000; }
        canvas { display: block; }
    </style>
</head>
<body>
    <script type="module">
        import * as THREE from 'https://unpkg.com/three@0.160.0/build/three.module.js';

        // Scene setup
        const scene = new THREE.Scene();
        const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
        const renderer = new THREE.WebGLRenderer({ antialias: true });

        renderer.setSize(window.innerWidth, window.innerHeight);
        renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
        document.body.appendChild(renderer.domElement);

        // Your 3D content here
        // ...

        camera.position.z = 5;

        // Animation loop
        renderer.setAnimationLoop((time) => {
            renderer.render(scene, camera);
        });

        // Handle resize
        window.addEventListener('resize', () => {
            camera.aspect = window.innerWidth / window.innerHeight;
            camera.updateProjectionMatrix();
            renderer.setSize(window.innerWidth, window.innerHeight);
        });
    </script>
</body>
</html>

Geometries

Built-in primitives cover most simple app needs. Use BufferGeometry only for custom shapes.

Common primitives:

BoxGeometry(width, height, depth) - cubes, boxes
SphereGeometry(radius, widthSegments, heightSegments) - balls, planets
CylinderGeometry(radiusTop, radiusBottom, height) - tubes, cylinders
TorusGeometry(radius, tube) - donuts, rings
PlaneGeometry(width, height) - floors, walls, backgrounds
ConeGeometry(radius, height) - spikes, cones
IcosahedronGeometry(radius, detail) - low-poly spheres (detail=0)

Usage:

const geometry = new THREE.BoxGeometry(1, 1, 1);
const material = new THREE.MeshStandardMaterial({ color: 0x44aa88 });
const mesh = new THREE.Mesh(geometry, material);
scene.add(mesh);

Materials

Choose material based on lighting needs and visual style.

Material selection guide:

MeshBasicMaterial - No lighting, flat colors. Use for: UI, wireframes, unlit effects
MeshStandardMaterial - PBR lighting. Default for realistic surfaces
MeshPhysicalMaterial - Advanced PBR with clearcoat, transmission. Glass, water
MeshNormalMaterial - Debug, rainbow colors based on normals
MeshPhongMaterial - Legacy, shininess control. Faster than Standard

Common material properties:

{
    color: 0x44aa88,           // Hex color
    roughness: 0.5,            // 0=glossy, 1=matte (Standard/Physical)
    metalness: 0.0,            // 0=non-metal, 1=metal (Standard/Physical)
    emissive: 0x000000,        // Self-illumination color
    wireframe: false,          // Show edges only
    transparent: false,        // Enable transparency
    opacity: 1.0,              // 0=invisible, 1=opaque (needs transparent:true)
    side: THREE.FrontSide      // FrontSide, BackSide, DoubleSide
}

Lighting

No light = black screen (except BasicMaterial/NormalMaterial).

Light types:

AmbientLight(intensity) - Base illumination everywhere. Use 0.3-0.5
DirectionalLight(color, intensity) - Sun-like, parallel rays. Cast shadows
PointLight(color, intensity, distance) - Light bulb, emits in all directions
SpotLight(color, intensity, angle, penumbra) - Flashlight, cone of light

Typical lighting setup:

const ambientLight = new THREE.AmbientLight(0xffffff, 0.4);
scene.add(ambientLight);

const mainLight = new THREE.DirectionalLight(0xffffff, 1);
mainLight.position.set(5, 10, 7);
scene.add(mainLight);

const fillLight = new THREE.DirectionalLight(0x88ccff, 0.5);
fillLight.position.set(-5, 0, -5);
scene.add(fillLight);

Shadows (advanced, use when needed):

renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;

mainLight.castShadow = true;
mainLight.shadow.mapSize.width = 2048;
mainLight.shadow.mapSize.height = 2048;

mesh.castShadow = true;
mesh.receiveShadow = true;

Animation

Transform objects over time using the animation loop.

Animation patterns:

Continuous rotation:

renderer.setAnimationLoop((time) => {
    mesh.rotation.x = time * 0.001;
    mesh.rotation.y = time * 0.0005;
    renderer.render(scene, camera);
});

Wave/bobbing motion:

renderer.setAnimationLoop((time) => {
    mesh.position.y = Math.sin(time * 0.002) * 0.5;
    renderer.render(scene, camera);
});

Mouse interaction:

const mouse = new THREE.Vector2();

window.addEventListener('mousemove', (event) => {
    mouse.x = (event.clientX / window.innerWidth) * 2 - 1;
    mouse.y = -(event.clientY / window.innerHeight) * 2 + 1;
});

renderer.setAnimationLoop(() => {
    mesh.rotation.x = mouse.y * 0.5;
    mesh.rotation.y = mouse.x * 0.5;
    renderer.render(scene, camera);
});

Camera Controls

Import OrbitControls from examples for interactive camera movement:

<script type="module">
    import * as THREE from 'https://unpkg.com/three@0.160.0/build/three.module.js';
    import { OrbitControls } from 'https://unpkg.com/three@0.160.0/examples/jsm/controls/OrbitControls.js';

    // ... scene setup ...

    const controls = new OrbitControls(camera, renderer.domElement);
    controls.enableDamping = true;
    controls.dampingFactor = 0.05;

    renderer.setAnimationLoop(() => {
        controls.update();
        renderer.render(scene, camera);
    });
</script>

Common Scene Patterns

Rotating Cube (Hello World)

const geometry = new THREE.BoxGeometry(1, 1, 1);
const material = new THREE.MeshStandardMaterial({ color: 0x00ff88 });
const cube = new THREE.Mesh(geometry, material);
scene.add(cube);

renderer.setAnimationLoop((time) => {
    cube.rotation.x = time * 0.001;
    cube.rotation.y = time * 0.001;
    renderer.render(scene, camera);
});

Floating Particle Field

const particleCount = 1000;
const geometry = new THREE.BufferGeometry();
const positions = new Float32Array(particleCount * 3);

for (let i = 0; i < particleCount * 3; i += 3) {
    positions[i] = (Math.random() - 0.5) * 50;
    positions[i + 1] = (Math.random() - 0.5) * 50;
    positions[i + 2] = (Math.random() - 0.5) * 50;
}

geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3));
const material = new THREE.PointsMaterial({ color: 0xffffff, size: 0.1 });
const particles = new THREE.Points(geometry, material);
scene.add(particles);

Animated Background with Foreground Object

// Background grid
const gridHelper = new THREE.GridHelper(50, 50, 0x444444, 0x222222);
scene.add(gridHelper);

// Foreground object
const mainGeometry = new THREE.IcosahedronGeometry(1, 0);
const mainMaterial = new THREE.MeshStandardMaterial({
    color: 0xff6600,
    flatShading: true
});
const mainMesh = new THREE.Mesh(mainGeometry, mainMaterial);
scene.add(mainMesh);

Colors

Three.js uses hexadecimal color format: 0xRRGGBB

Common hex colors:

Black: 0x000000, White: 0xffffff
Red: 0xff0000, Green: 0x00ff00, Blue: 0x0000ff
Cyan: 0x00ffff, Magenta: 0xff00ff, Yellow: 0xffff00
Orange: 0xff8800, Purple: 0x8800ff, Pink: 0xff0088

Anti-Patterns to Avoid

Basic Setup Mistakes

❌ Not importing OrbitControls from correct path Why bad: Controls won't load, THREE.OrbitControls is undefined in modern Three.js Better: Use import { OrbitControls } from 'three/addons/controls/OrbitControls.js' or unpkg examples/jsm path

❌ Forgetting to add object to scene Why bad: Object won't render, silent failure Better: Always call scene.add(object) after creating meshes/lights

❌ Using old requestAnimationFrame pattern instead of setAnimationLoop Why bad: More verbose, doesn't handle XR/WebXR automatically Better: renderer.setAnimationLoop((time) => { ... })

Performance Issues

❌ Creating new geometries in animation loop Why bad: Massive memory allocation, frame rate collapse Better: Create geometry once, reuse it. Transform only position/rotation/scale

❌ Using too many segments on primitives Why bad: Unnecessary vertices, GPU overhead Better: Default segments are usually fine. SphereGeometry(1, 32, 16) not SphereGeometry(1, 128, 64)

❌ Not setting pixelRatio cap Why bad: 4K/5K displays run at full resolution, poor performance Better: Math.min(window.devicePixelRatio, 2)

Code Organization

❌ Everything in one giant function Why bad: Hard to modify, hard to debug Better: Separate setup into functions: createScene(), createLights(), createMeshes()

❌ Hardcoding all values Why bad: Difficult to tweak and experiment Better: Define constants at top: const CONFIG = { color: 0x00ff88, speed: 0.001 }

Variation Guidance

IMPORTANT: Each Three.js app should feel unique and context-appropriate.

Vary by scenario:

Portfolio/showcase: Elegant, smooth animations, muted colors
Game/interactive: Bright colors, snappy controls, particle effects
Data visualization: Clean lines, grid helpers, clear labels
Background effect: Subtle, slow movement, dark/gradient backgrounds
Product viewer: Realistic lighting, PBR materials, smooth orbit

Vary visual elements:

Geometry choice: Not everything needs to be a cube. Explore spheres, tori, icosahedra
Material style: Mix flat shaded, glossy, metallic, wireframe
Color palettes: Use complementary, analogous, or monochromatic schemes
Animation style: Rotation, oscillation, wave motion, mouse tracking

Avoid converging on:

Default green cube as first example every time
Same camera angle (front-facing, z=5)
Identical lighting setup (always directional light at 1,1,1)

Remember

Three.js is a tool for interactive 3D on the web.

Effective Three.js apps:

Start with the scene graph mental model
Use primitives as building blocks
Keep animations simple and performant
Vary visual style based on purpose
Import from modern ES module paths

Modern Three.js (r150+) uses ES modules from three package or CDN. CommonJS patterns and global THREE variable are legacy.

Claude is capable of creating elegant, performant 3D web experiences. These patterns guide the way—they don't limit the result.

For specific topics, see the Reference Files table at the top of this document.

Threejs Builder

File contents

Three.js Builder

Reference Files

Philosophy: The Scene Graph Mental Model

Three.js Coordinate System (CRITICAL)

The Axes

GLTF Model Default Orientation

Camera-Relative Movement (CRITICAL for Games)

Quick Start: Essential Setup

Minimal HTML Template

Geometries

Materials

Lighting

Animation

Camera Controls

Common Scene Patterns

Rotating Cube (Hello World)

Floating Particle Field

Animated Background with Foreground Object

Colors

Anti-Patterns to Avoid

Basic Setup Mistakes

Performance Issues

Code Organization

Variation Guidance

Remember

Frequently asked questions

Threejs Builder

File contents

Three.js Builder

Reference Files

Philosophy: The Scene Graph Mental Model

Three.js Coordinate System (CRITICAL)

The Axes

GLTF Model Default Orientation

Camera-Relative Movement (CRITICAL for Games)

Quick Start: Essential Setup

Minimal HTML Template

Geometries

Materials

Lighting

Animation

Camera Controls

Common Scene Patterns

Rotating Cube (Hello World)

Floating Particle Field

Animated Background with Foreground Object

Colors

Anti-Patterns to Avoid

Basic Setup Mistakes

Performance Issues

Code Organization

Variation Guidance

Remember

Related skills

Frequently asked questions

How do I install the Threejs Builder skill?

What does the Threejs Builder skill do?

Is Threejs Builder safe to use?

Which AI agents work with Threejs Builder?

Is Threejs Builder free to use?

Who published Threejs Builder?