
threejs-geometry
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.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/calesthio/openmontage --skill threejs-geometry- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads threejs-geometry automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Three.js Geometry
Quick Start
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
// 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
// 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
// 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
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
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
// 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
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)
// 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
// 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
// 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
// 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.
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
// 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.
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
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
geometry.computeBoundingBox();
geometry.center(); // Move vertices so center is at origin
Scale to Fit
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
const clone = geometry.clone();
clone.rotateX(Math.PI / 2);
clone.translate(0, 1, 0);
clone.scale(2, 2, 2);
Morph Targets
// 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
- Use indexed geometry: Reuse vertices with indices
- Merge static meshes: Reduce draw calls with
mergeGeometries - Use InstancedMesh: For many identical objects
- Choose appropriate segment counts: More segments = smoother but slower
- Dispose unused geometry:
geometry.dispose()
// 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 Object3Dthreejs-materials- Material types for meshesthreejs-shaders- Custom vertex manipulation
FAQ
What does the threejs-geometry skill do?
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.
How do I install threejs-geometry?
Run npx skills add https://github.com/calesthio/openmontage --skill threejs-geometry in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/threejs-geometry/ (personal) or .claude/skills/threejs-geometry/ (project).
Which AI agents can use threejs-geometry?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is threejs-geometry safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains threejs-geometry?
It is published by calesthio in calesthio/openmontage. It has 1,054 recorded installs.
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