Mat3D VectorPairRotation(const Vec3D& from1, const Vec3D& from2, const Vec3D& to1, const Vec3D& to2) {
Vec3D from_x = (from1.normalized()+from2.normalized()).normalized();
Vec3D from_y = (from1.normalized()-from2.normalized()).normalized();
Mat3D Mfrom(from_x, from_y, from_x%from_y);
Vec3D to_x = (to1.normalized()+to2.normalized()).normalized();
Vec3D to_y = (to1.normalized()-to2.normalized()).normalized();
Mat3D Mto(to_x, to_y, to_x%to_y);
return Mto * Mfrom.inverse();
}
void OptimalRotation::addVectorPair(const Vec3D &from, const Vec3D &to) {
stack += to.normalized()^from.normalized();
valid=false;
}