Return 3D lighting for polygons with vertices XYZ. If NXYZ is specified, XYZ should be sum(nxyz)-by-3, with NXYZ being the list of numbers of vertices for each polygon (as for the plfp function; see page 39). If NXYZ is not specified, XYZ should be a quadrilateral mesh, ni-by-nj-by-3 (as for the plf function; see page 35). In the first case, the return value is len (NXYZ) long; in the second case, the return value is (ni-1)-by-(nj-1).
The parameters of the lighting calculation are set by the light3 function (see "Lighting Parameters" on page 57).