I think maybe the easiest way to tackle the problem is to have the language describe surfaces instead of solid objects, and let every surface have a normal and two materials. This might be the most natural representation for a ray tracer.

We are working on surface support in Makie to some degree: https://github.com/MakieOrg/Makie.jl/pull/5516 If we get funding, we may also support stuff like NURBS. Obviously, once that gets merged, we do want to also add Raytracing support for it ;)