Hello wizards!

I have a shader/vex question regarding the refraction shader.
So I have this very non conventional render where I am rendering a water cylinder with a custom lens shader. Doing kind of an inwards cylindrical camera.
The goal is to place this render on a cylindrical display. So at the beginning the idea was to be able to see the other side of the water but now, it was decided to remove it completely.

So I said ok, I can reduce the clipping plane of the camera that should get rid of the other side of the water cylinder, but, then of course I can still see the other side of the water when it is below the water surface, because that's what the first refraction ray will be. I then thought, well maybe I can add a black cylinder but then that will just make the refraction rays stop sooner and the resulting image will be darker.

So my questions will be:

- Is there a way to limit the distance of the refraction rays?
- If not, is there a way to output a refraction VEX variable based on the depth of the refracted ray? So that I can get an image plane that outputs only the furthest or closest refracted surface so that I can mask those.

I am using the glass shader preset from the material library, so nothing custom other than the lens shader, which is a modified reference to Paul's guide on custom lens shaders [www.sidefx.com] using VEX

So basically by now, what I need would be a render like the one with the Far Clip at 3.5 but without the refracted water from the other side.

*The viewport screenshot is a reference of how the water mesh looks like