normal expression function

Returns the components of the surface normal specific UV coordinates.

See also: unituv, primuv, primduv, curvature

u and v are unit values, defined in the [0,1] interval. If the primitive is a mesh, u and v are defined in terms its number of rows and columns.

index specifies which component to return, where 0 means X, 1 means Y, and 2 means Z.