Vector pass for Focal length animation

The Vector pass stores the mouvements of objects for post-processing of animations, enabling very important features such as :

• temporal denoising (which removes flickers for example)
• using a displace node
• comparing pixels from surrounding frames

Nevertheless, when the focal length changes along frames, the Vector pass is no longer representative of the apparent motion at the camera, preventing any useful usage described above.

Having a distinct Vector for the camera lens animation, or including the associated transformation within the existing Vector pass, would be very useful for post-processing.