Function computeDistanceScale

src/utils/sim3dAlignment.ts:16–38

(
  point1: THREE.Vector3,
  point2: THREE.Vector3,
  targetDistance: number
)

 * Scale is applied uniformly about the midpoint of the two points.
 */
export function computeDistanceScale(
  point1: THREE.Vector3,
  point2: THREE.Vector3,
  targetDistance: number
): Sim3d {
  const currentDistance = point1.distanceTo(point2);

  if (currentDistance < 1e-10) {
    return identitySim3d();
  }

  const scale = targetDistance / currentDistance;
  const midpoint = new THREE.Vector3()
    .addVectors(point1, point2)
    .multiplyScalar(0.5);
  const translation = midpoint.clone().multiplyScalar(1 - scale);

  return {
    scale,
    rotation: new THREE.Quaternion(),
    translation,
  };
}

/**
 * Compute translation transform to move a point to the world origin.