Note that the data in the RixShadingContext are available directly in scripts. Currently that includes: P, Pobj, Vn, VLen, Nn, Ngn, Tn, s, t, u, v, w, curvature, curvature_u, curvature_v, objectId; if an input is given one of these names, it will be ignored in favor of the RixShadingContext data.
