Return the signed length of the projection of vector v on vector w.

    Returns the full vector result of projection_v3().

def projection_as_vec_v3(v, w):
    """Return the signed length of the projection of vector v on vector w.

    Returns the full vector result of projection_v3().
    """
    proj_len = projection_v3(v, w)
    return scale_v3(v, proj_len)