rotationMatrix :: Vect -> Vect -> Mat
rotationMatrix up z = inv $ fromColumns [up' `cross` z', up', z', unitV 3]
  where
    up' = normalize up
    z' = normalize z
rotationMatrix :: Vect -> Vect -> Mat
rotationMatrix up z = inv $ fromColumns [up' `cross` z', up', z', unitV 3]
  where
    up' = normalize up
    z' = normalize z
rotationMatrix up z = inv $ fromColumns [up' `cross` z', up', z', unitV 3]
  where
    up' = normalize up
    z' = normalize z