Toon shading

We wanted to get a cartoon look to our characters so I have been experimenting with cel/toon shading. I have never used this before so it took me a bit of time and a bit of research to it to work how we wanted it to. I think I managed to achieve the correct look. It makes it look 2D even though it is a 3D model.

I realised that you need to use ramp shaders to get the shadows and then the black line is added automatically. I had to change the colours in the ramp shader by eye which is why it looks lighter than some of the other tests. I can change the amount of shadow there is as well by changing the difference in space between the colours. 

I did some more tests with different colours to see how they would look. Below is an example. The others colours did not quite look as good as the purple so we have all decided to stick to the purple for the rat.

It works for the rat but I don't think this will work for the cat or other items as the cat has a blotchy texture on its fur - not just block colours. I will research more into this to see if I can attach the blotchy texture to the ramp shader so that it will work with a texture map and not only block colours.