Hey there, I am working on trying to get this snake eye effect when I “dilate” the pupil of the eye. I am trying to do this using ramps into the uv space but I’m open to other ideas, except the modeling of the eye. I would like the inner circle to strictly scale horizontally not vertically like it is in the gif.
Currently (and the way I have done other eyes in the past) I have a 2048x1024 texture being pumped into an aiImge node, which then has inputs to it’s UVCoords X and Y.
X = a radial ramp
Y = a circular ramp
The radial ramp, wraps the texture around into a circle, and then the circular ramp controls the dilation by changing the black value. Below is a gif example of my setup.
Any input or direction would be great 
I’ve tried some UVTransform nodes from arnold, and some other ramps plugged into the radial ramp but I have a bit limited knowledge on how to manipulate ramps in a more advanced way.