code: public Matrix3 setToRotation (IVector3 from, IVector3 to) {
          float angle = from.angle(to);
          return (angle < 0.0001f) ?
              setToIdentity() : setToRotation(angle, from.cross(to).normalizeLocal());
      }
docs: Sets this to a rotation matrix that rotates one vector onto another.
  
  @return a reference to this matrix, for chaining.