I'm trying to demonstrate light bending due to gravity, but my knowledge of Blender isn't up to the job.
As a test I have a sphere with the Glassy BSDF shader. The colour is set to white, and I've linked a Fresnel node to the IOR input. What I'm trying to do is have the IOR equal 1 at the edges of the sphere, so that no refraction happens, and then towards the center have the IOR quite high, so that it bends the light a lot.
The problem I'm having is mapping the Fresnel output to the IOR input, no matter what I do it never seems to work. Is there a scalar curve node anywhere that I can use to remap the Fresnel factor the way I want it?
Alternative would there be a way of doing this with a volumetric shader?