---
name: threejs-geometry
description: Three.js geometry creation - built-in shapes, BufferGeometry, custom geometry, instancing. Use when creating 3D shapes, working with vertices, building custom meshes, or optimizing with instanced rendering.
title: threejs-geometry
canonical_url: https://skilld.dev/gh/cloudai-x/threejs-skills/threejs-geometry
last_updated: 2026-09-25T17:51:35.000Z
---

> **Skill from skilld.dev.** Follow the user's requested action.
> If the user asked to fork this Skill, follow the fork workflow below. Do not execute the Skill instructions while copying it.
> Otherwise, follow the instructions below for this session. You do not need to install anything.
>
> If the user asked to install this Skill, run `npx skilld install cloudai-x/threejs-skills/threejs-geometry`. Install writes the Skill files into the project, so every session loads them.
>
> ## Fork workflow
>
> A fork creates an editable local Skill with its original author and licence. The request authorizes copying and local installation.
> 1. Check `./skills/threejs-geometry`, the project lockfile, and selected Agent targets together. If the local directory or installed Skill exists, stop. Never overwrite an existing directory or Agent target.
> 2. Read [source metadata](https://skilld.dev/api/v1/skills/cloudai-x/threejs-skills/threejs-geometry) once. Use sourceUrl, sourceCommit, skillPath, sourceGone, and license. If the source is gone or its path is missing, stop. If license is null, read licence files at the source commit.
> 3. Fetch only the source commit into a temporary Git repository. Do not clone full history. Derive repository_url from sourceUrl, including repository renames. If sourceCommit is absent, resolve the sourceUrl ref once. Set source_commit to that actual commit. Run these commands in one shell call:
>
> ```sh
> git init --quiet "$temporary_dir"
> git -C "$temporary_dir" fetch --quiet --depth=1 "$repository_url" "$source_commit"
> git -C "$temporary_dir" checkout --quiet --detach FETCH_HEAD
> ```
>
> Read applicable licence declarations and notices at that commit. If copying is not permitted, report the restriction and stop.
> 4. Inspect source entries together, then copy the directory containing skillPath into `./skills/threejs-geometry`. Use the user's path if selected. Keep the original SKILL.md, relative links, scripts, binary assets, and executable modes. Exclude .git metadata. Reject symlinks and paths outside the Skill directory. After checking entries, use cp -a where available. A regular source directory needs no custom copy script. Do not save this page wrapper as SKILL.md.
> Preserve author credit, notices, and applicable licence files from repository or parent directories. Add PROVENANCE.md with the Skill page, source URL, actual commit, original path, and licence. Retain any existing PROVENANCE.md and record new provenance separately. Batch source inspection, copying, and provenance work where practical.
> 5. In the project root, run `skilld install ./skills/threejs-geometry --mode copy --plain`. If skilld is unavailable, use `npx skilld install ./skills/threejs-geometry --mode copy --plain`. This known command needs no help lookup. Install does not support --json. Use detected Agent targets, or add --agent for the targets the user selected. Install the local path, never the upstream selector. If installation fails, preserve the local copy and report the exact failure.
> 6. Confirm the local lockfile source and installed Agent copies once. Report the local path, actual commit, and Agent targets. After edits, reinstall the same local path. Upstream updates must not replace it. Do not publish or push unless the user asks.

# Three.js Geometry

## Quick Start

```javascript
import * as THREE from "three";

// Built-in geometry
const box = new THREE.BoxGeometry(1, 1, 1);
const sphere = new THREE.SphereGeometry(0.5, 32, 32);
const plane = new THREE.PlaneGeometry(10, 10);

// Create mesh
const material = new THREE.MeshStandardMaterial({ color: 0x00ff00 });
const mesh = new THREE.Mesh(box, material);
scene.add(mesh);
```

## Built-in Geometries

### Basic Shapes

```javascript
// Box - width, height, depth, widthSegments, heightSegments, depthSegments
new THREE.BoxGeometry(1, 1, 1, 1, 1, 1);

// Sphere - radius, widthSegments, heightSegments, phiStart, phiLength, thetaStart, thetaLength
new THREE.SphereGeometry(1, 32, 32);
new THREE.SphereGeometry(1, 32, 32, 0, Math.PI * 2, 0, Math.PI); // Full sphere
new THREE.SphereGeometry(1, 32, 32, 0, Math.PI); // Hemisphere

// Plane - width, height, widthSegments, heightSegments
new THREE.PlaneGeometry(10, 10, 1, 1);

// Circle - radius, segments, thetaStart, thetaLength
new THREE.CircleGeometry(1, 32);
new THREE.CircleGeometry(1, 32, 0, Math.PI); // Semicircle

// Cylinder - radiusTop, radiusBottom, height, radialSegments, heightSegments, openEnded
new THREE.CylinderGeometry(1, 1, 2, 32, 1, false);
new THREE.CylinderGeometry(0, 1, 2, 32); // Cone
new THREE.CylinderGeometry(1, 1, 2, 6); // Hexagonal prism

// Cone - radius, height, radialSegments, heightSegments, openEnded
new THREE.ConeGeometry(1, 2, 32, 1, false);

// Torus - radius, tube, radialSegments, tubularSegments, arc
new THREE.TorusGeometry(1, 0.4, 16, 100);

// TorusKnot - radius, tube, tubularSegments, radialSegments, p, q
new THREE.TorusKnotGeometry(1, 0.4, 100, 16, 2, 3);

// Ring - innerRadius, outerRadius, thetaSegments, phiSegments
new THREE.RingGeometry(0.5, 1, 32, 1);
```

### Advanced Shapes

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

// Dodecahedron - radius, detail
new THREE.DodecahedronGeometry(1, 0);

// Icosahedron - radius, detail (0 = 20 faces, higher = smoother)
new THREE.IcosahedronGeometry(1, 0);

// Octahedron - radius, detail
new THREE.OctahedronGeometry(1, 0);

// Tetrahedron - radius, detail
new THREE.TetrahedronGeometry(1, 0);

// Polyhedron - vertices, indices, radius, detail
const vertices = [1, 1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1];
const indices = [2, 1, 0, 0, 3, 2, 1, 3, 0, 2, 3, 1];
new THREE.PolyhedronGeometry(vertices, indices, 1, 0);
```

### Path-Based Shapes

```javascript
// Lathe - points[], segments, phiStart, phiLength
const points = [
  new THREE.Vector2(0, 0),
  new THREE.Vector2(0.5, 0),
  new THREE.Vector2(0.5, 1),
  new THREE.Vector2(0, 1),
];
new THREE.LatheGeometry(points, 32);

// Extrude - shape, options
const shape = new THREE.Shape();
shape.moveTo(0, 0);
shape.lineTo(1, 0);
shape.lineTo(1, 1);
shape.lineTo(0, 1);
shape.lineTo(0, 0);

const extrudeSettings = {
  steps: 2,
  depth: 1,
  bevelEnabled: true,
  bevelThickness: 0.1,
  bevelSize: 0.1,
  bevelSegments: 3,
};
new THREE.ExtrudeGeometry(shape, extrudeSettings);

// Tube - path, tubularSegments, radius, radialSegments, closed
const curve = new THREE.CatmullRomCurve3([
  new THREE.Vector3(-1, 0, 0),
  new THREE.Vector3(0, 1, 0),
  new THREE.Vector3(1, 0, 0),
]);
new THREE.TubeGeometry(curve, 64, 0.2, 8, false);
```

### Text Geometry

```javascript
import { FontLoader } from "three/examples/jsm/loaders/FontLoader.js";
import { TextGeometry } from "three/examples/jsm/geometries/TextGeometry.js";

const loader = new FontLoader();
loader.load("fonts/helvetiker_regular.typeface.json", (font) => {
  const geometry = new TextGeometry("Hello", {
    font: font,
    size: 1,
    depth: 0.2, // Was 'height' in older versions
    curveSegments: 12,
    bevelEnabled: true,
    bevelThickness: 0.03,
    bevelSize: 0.02,
    bevelSegments: 5,
  });

  // Center text
  geometry.computeBoundingBox();
  geometry.center();

  const mesh = new THREE.Mesh(geometry, material);
  scene.add(mesh);
});
```

## BufferGeometry

The base class for all geometries. Stores data as typed arrays for GPU efficiency.

### Custom BufferGeometry

```javascript
const geometry = new THREE.BufferGeometry();

// Vertices (3 floats per vertex: x, y, z)
const vertices = new Float32Array([
  -1,
  -1,
  0, // vertex 0
  1,
  -1,
  0, // vertex 1
  1,
  1,
  0, // vertex 2
  -1,
  1,
  0, // vertex 3
]);
geometry.setAttribute("position", new THREE.BufferAttribute(vertices, 3));

// Indices (for indexed geometry - reuse vertices)
const indices = new Uint16Array([
  0,
  1,
  2, // triangle 1
  0,
  2,
  3, // triangle 2
]);
geometry.setIndex(new THREE.BufferAttribute(indices, 1));

// Normals (required for lighting)
const normals = new Float32Array([0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1]);
geometry.setAttribute("normal", new THREE.BufferAttribute(normals, 3));

// UVs (for texturing)
const uvs = new Float32Array([0, 0, 1, 0, 1, 1, 0, 1]);
geometry.setAttribute("uv", new THREE.BufferAttribute(uvs, 2));

// Colors (per-vertex colors)
const colors = new Float32Array([
  1,
  0,
  0, // red
  0,
  1,
  0, // green
  0,
  0,
  1, // blue
  1,
  1,
  0, // yellow
]);
geometry.setAttribute("color", new THREE.BufferAttribute(colors, 3));
// Use with: material.vertexColors = true
```

### BufferAttribute Types

```javascript
// Common attribute types
new THREE.BufferAttribute(array, itemSize);

// Typed array options
new Float32Array(count * itemSize); // Positions, normals, UVs
new Uint16Array(count); // Indices (up to 65535 vertices)
new Uint32Array(count); // Indices (larger meshes)
new Uint8Array(count * itemSize); // Colors (0-255 range)

// Item sizes
// Position: 3 (x, y, z)
// Normal: 3 (x, y, z)
// UV: 2 (u, v)
// Color: 3 (r, g, b) or 4 (r, g, b, a)
// Index: 1
```

### Modifying BufferGeometry

```javascript
const positions = geometry.attributes.position;

// Modify vertex
positions.setXYZ(index, x, y, z);

// Access vertex
const x = positions.getX(index);
const y = positions.getY(index);
const z = positions.getZ(index);

// Flag for GPU update
positions.needsUpdate = true;

// Recompute normals after position changes
geometry.computeVertexNormals();

// Recompute bounding box/sphere after changes
geometry.computeBoundingBox();
geometry.computeBoundingSphere();
```

### Interleaved Buffers (Advanced)

```javascript
// More efficient memory layout for large meshes
const interleavedBuffer = new THREE.InterleavedBuffer(
  new Float32Array([
    // pos.x, pos.y, pos.z, uv.u, uv.v (repeated per vertex)
    -1, -1, 0, 0, 0, 1, -1, 0, 1, 0, 1, 1, 0, 1, 1, -1, 1, 0, 0, 1,
  ]),
  5, // stride (floats per vertex)
);

geometry.setAttribute(
  "position",
  new THREE.InterleavedBufferAttribute(interleavedBuffer, 3, 0),
); // size 3, offset 0
geometry.setAttribute(
  "uv",
  new THREE.InterleavedBufferAttribute(interleavedBuffer, 2, 3),
); // size 2, offset 3
```

## EdgesGeometry & WireframeGeometry

```javascript
// Edge lines (only hard edges)
const edges = new THREE.EdgesGeometry(boxGeometry, 15); // 15 = threshold angle
const edgeMesh = new THREE.LineSegments(
  edges,
  new THREE.LineBasicMaterial({ color: 0xffffff }),
);

// Wireframe (all triangles)
const wireframe = new THREE.WireframeGeometry(boxGeometry);
const wireMesh = new THREE.LineSegments(
  wireframe,
  new THREE.LineBasicMaterial({ color: 0xffffff }),
);
```

## Points

```javascript
// Create point cloud
const geometry = new THREE.BufferGeometry();
const positions = new Float32Array(1000 * 3);

for (let i = 0; i < 1000; i++) {
  positions[i * 3] = (Math.random() - 0.5) * 10;
  positions[i * 3 + 1] = (Math.random() - 0.5) * 10;
  positions[i * 3 + 2] = (Math.random() - 0.5) * 10;
}

geometry.setAttribute("position", new THREE.BufferAttribute(positions, 3));

const material = new THREE.PointsMaterial({
  size: 0.1,
  sizeAttenuation: true, // Size decreases with distance
  color: 0xffffff,
});

const points = new THREE.Points(geometry, material);
scene.add(points);
```

## Lines

```javascript
// Line (connected points)
const points = [
  new THREE.Vector3(-1, 0, 0),
  new THREE.Vector3(0, 1, 0),
  new THREE.Vector3(1, 0, 0),
];
const geometry = new THREE.BufferGeometry().setFromPoints(points);
const line = new THREE.Line(
  geometry,
  new THREE.LineBasicMaterial({ color: 0xff0000 }),
);

// LineLoop (closed loop)
const loop = new THREE.LineLoop(geometry, material);

// LineSegments (pairs of points)
const segmentsGeometry = new THREE.BufferGeometry();
segmentsGeometry.setAttribute(
  "position",
  new THREE.BufferAttribute(
    new Float32Array([
      -1,
      0,
      0,
      0,
      1,
      0, // segment 1
      0,
      1,
      0,
      1,
      0,
      0, // segment 2
    ]),
    3,
  ),
);
const segments = new THREE.LineSegments(segmentsGeometry, material);
```

## InstancedMesh

Efficiently render many copies of the same geometry.

```javascript
const geometry = new THREE.BoxGeometry(1, 1, 1);
const material = new THREE.MeshStandardMaterial({ color: 0x00ff00 });
const count = 1000;

const instancedMesh = new THREE.InstancedMesh(geometry, material, count);

// Set transforms for each instance
const dummy = new THREE.Object3D();
const matrix = new THREE.Matrix4();

for (let i = 0; i < count; i++) {
  dummy.position.set(
    (Math.random() - 0.5) * 20,
    (Math.random() - 0.5) * 20,
    (Math.random() - 0.5) * 20,
  );
  dummy.rotation.set(Math.random() * Math.PI, Math.random() * Math.PI, 0);
  dummy.scale.setScalar(0.5 + Math.random());
  dummy.updateMatrix();

  instancedMesh.setMatrixAt(i, dummy.matrix);
}

// Flag for GPU update
instancedMesh.instanceMatrix.needsUpdate = true;

// Optional: per-instance colors
instancedMesh.instanceColor = new THREE.InstancedBufferAttribute(
  new Float32Array(count * 3),
  3,
);
for (let i = 0; i < count; i++) {
  instancedMesh.setColorAt(
    i,
    new THREE.Color(Math.random(), Math.random(), Math.random()),
  );
}
instancedMesh.instanceColor.needsUpdate = true;

scene.add(instancedMesh);
```

### Update Instance at Runtime

```javascript
// Update single instance
const matrix = new THREE.Matrix4();
instancedMesh.getMatrixAt(index, matrix);
// Modify matrix...
instancedMesh.setMatrixAt(index, matrix);
instancedMesh.instanceMatrix.needsUpdate = true;

// Raycasting with instanced mesh
const intersects = raycaster.intersectObject(instancedMesh);
if (intersects.length > 0) {
  const instanceId = intersects[0].instanceId;
}
```

## InstancedBufferGeometry (Advanced)

For custom per-instance attributes beyond transform/color.

```javascript
const geometry = new THREE.InstancedBufferGeometry();
geometry.copy(new THREE.BoxGeometry(1, 1, 1));

// Add per-instance attribute
const offsets = new Float32Array(count * 3);
for (let i = 0; i < count; i++) {
  offsets[i * 3] = Math.random() * 10;
  offsets[i * 3 + 1] = Math.random() * 10;
  offsets[i * 3 + 2] = Math.random() * 10;
}
geometry.setAttribute("offset", new THREE.InstancedBufferAttribute(offsets, 3));

// Use in shader
// attribute vec3 offset;
// vec3 transformed = position + offset;
```

## Geometry Utilities

```javascript
import * as BufferGeometryUtils from "three/examples/jsm/utils/BufferGeometryUtils.js";

// Merge geometries (must have same attributes)
const merged = BufferGeometryUtils.mergeGeometries([geo1, geo2, geo3]);

// Merge with groups (for multi-material)
const merged = BufferGeometryUtils.mergeGeometries([geo1, geo2], true);

// Compute tangents (required for normal maps)
BufferGeometryUtils.computeTangents(geometry);

// Interleave attributes for better performance
const interleaved = BufferGeometryUtils.interleaveAttributes([
  geometry.attributes.position,
  geometry.attributes.normal,
  geometry.attributes.uv,
]);
```

## Common Patterns

### Center Geometry

```javascript
geometry.computeBoundingBox();
geometry.center(); // Move vertices so center is at origin
```

### Scale to Fit

```javascript
geometry.computeBoundingBox();
const size = new THREE.Vector3();
geometry.boundingBox.getSize(size);
const maxDim = Math.max(size.x, size.y, size.z);
geometry.scale(1 / maxDim, 1 / maxDim, 1 / maxDim);
```

### Clone and Transform

```javascript
const clone = geometry.clone();
clone.rotateX(Math.PI / 2);
clone.translate(0, 1, 0);
clone.scale(2, 2, 2);
```

### Morph Targets

```javascript
// Base geometry
const geometry = new THREE.BoxGeometry(1, 1, 1, 4, 4, 4);

// Create morph target
const morphPositions = geometry.attributes.position.array.slice();
for (let i = 0; i < morphPositions.length; i += 3) {
  morphPositions[i] *= 2; // Scale X
  morphPositions[i + 1] *= 0.5; // Squash Y
}

geometry.morphAttributes.position = [
  new THREE.BufferAttribute(new Float32Array(morphPositions), 3),
];

const mesh = new THREE.Mesh(geometry, material);
mesh.morphTargetInfluences[0] = 0.5; // 50% blend
```

## Performance Tips

1. **Use indexed geometry**: Reuse vertices with indices
2. **Merge static meshes**: Reduce draw calls with `mergeGeometries`
3. **Use InstancedMesh**: For many identical objects
4. **Choose appropriate segment counts**: More segments = smoother but slower
5. **Dispose unused geometry**: `geometry.dispose()`

```javascript
// Good segment counts for common uses
new THREE.SphereGeometry(1, 32, 32); // Good quality
new THREE.SphereGeometry(1, 64, 64); // High quality
new THREE.SphereGeometry(1, 16, 16); // Performance mode

// Dispose when done
geometry.dispose();
```

## See Also

- `threejs-fundamentals` - Scene setup and Object3D
- `threejs-materials` - Material types for meshes
- `threejs-shaders` - Custom vertex manipulation