Picking - OpenGeometry

Raycast your scene with Three.js as usual. Then pass the hit to OpenGeometry.resolveHit:

import * as THREE from 'three';
import { OpenGeometry, Solid, OG_PRIMITIVE_CUBOID } from 'opengeometry';

await OpenGeometry.create(
  { wasmURL: '/opengeometry_bg.wasm' },
  { workerURL: '/tessellation-worker.js' },
);

const box = new Solid(OG_PRIMITIVE_CUBOID, { width: 1, height: 1, depth: 1 }, { ogId: 'box' });
const scene = new THREE.Scene();
scene.add(box);
scene.updateMatrixWorld();
OpenGeometry.flush({ geometry: 'sync' });

const raycaster = new THREE.Raycaster(new THREE.Vector3(0, 0.5, 5), new THREE.Vector3(0, 0, -1));
const [hit] = raycaster.intersectObject(scene, true);
const picked = hit ? OpenGeometry.resolveHit(hit) : undefined;
console.log(picked);

resolveHit returns { ogId, shapeRevision, faceId?, edgeId? }, or undefined when the hit is not on a body.

faceId is set for a hit on the surface. Find the face with body.getBrep().topology.faces.
edgeId is set for a hit on the outline.
shapeRevision tells you which revision of the shape was hit. After an edit, the ids can refer to other faces.

Outlines

A raycast hits a body’s outline only when pickOutline is on. It is on for wires and off for sheets and solids. Turn it on with body.setAppearance({ pickOutline: true }). Set raycaster.params.Line.threshold to the pick width that you want.

Copies of the display

body.clone() makes a display copy for Three.js only. It is not a body, so resolveHit returns undefined for a hit on it. Call its dispose() when you take it out of the scene.

Last modified on November 10, 2026