Function computePlaneAlignment

src/utils/sim3dAlignment.ts:113–127

(
  normal: [number, number, number],
  centroid: [number, number, number],
  targetUp: THREE.Vector3
)

 * and translates it to pass through the origin.
 */
export function computePlaneAlignment(
  normal: [number, number, number],
  centroid: [number, number, number],
  targetUp: THREE.Vector3
): Sim3d {
  const normalVec = new THREE.Vector3(normal[0], normal[1], normal[2]).normalize();
  const centroidVec = new THREE.Vector3(centroid[0], centroid[1], centroid[2]);

  const rotation = new THREE.Quaternion().setFromUnitVectors(normalVec, targetUp.clone().normalize());
  const rotatedCentroid = centroidVec.clone().applyQuaternion(rotation);
  const distanceAlongAxis = rotatedCentroid.dot(targetUp);
  const translation = targetUp.clone().multiplyScalar(-distanceAlongAxis);

  return { rotation, translation, scale: 1 };
}