Function composeSim3d

src/utils/sim3dTransforms.ts:145–157

(cFromB: Sim3d, bFromA: Sim3d)

 * - translation = t_c + scale_c * (R_c * t_b)
 */
export function composeSim3d(cFromB: Sim3d, bFromA: Sim3d): Sim3d {
  const scale = cFromB.scale * bFromA.scale;
  const rotation = cFromB.rotation.clone().multiply(bFromA.rotation).normalize();

  // t_result = t_c + scale_c * (R_c * t_b)
  const translation = bFromA.translation
    .clone()
    .applyQuaternion(cFromB.rotation)
    .multiplyScalar(cFromB.scale)
    .add(cFromB.translation);

  return { scale, rotation, translation };
}

/**
 * Transform camera pose (qvec, tvec) for world transformation.