Quote - The incident light angle node can only be used within lighting calculations (that is, in the graph, mainly with specular highlights), as it gives different values for each light source. That's why when trying to connect other outputs to that node, Vue normally warns you about the connexion being not pertinent.

Ok this was the reply I got from e-on software. I'm just trying to turn it into english. Thanks for the replies

 

What they mean is that it can only be used as a node connected to the specular output channel so it won't work for creating a toon type gradient plugged into the color channel.