Returns the value of a primitive attribute at a certain UV location.
primuv(surface_node, prim_num, attrib_name, attrib_index,
Evaluates the specified attribute at a parametric (u,v) position on the
primitive. u and v are unit values, defined in the
[0,1] interval. When
given the “P” or “Pw” attribute, the x, y, or z image of the (u,v)
domain point will be returned. If the primitive is a face type or a
circle, v is ignored.
if the primitive is a polygon or a mesh, u and v are defined in terms of the number of vertices, or rows or columns respectively. Currently, only the position attribute of quadric primitives can be evaluated.
primuv("/obj/geo1/tube1", 0, "Cd", 1, 0.7, 0.3)
Evaluates the Green component of the diffuse color attribute at a location on primitive 0 given by the parametric coordinates (0.7,0.3).