How do I make a material that selectively filters *and* reflects light?

I’m trying to model a material that acts like a mirror or glass depending on some property of the light passing through it (non-color property).

In a real world case, for example, we have a material that can reflect one polarization of light, but lets another polarization of light pass through. Although Unreal won’t model the polarization of the light, is there some information that can be tagged to light rays?

My initial thought was perhaps I could use the alpha channel of the light color as a filter, so if light has an alpha value of < 0.5, the light will reflect, otherwise it will pass through. Seeing how I’m new to Unreal, I’m not sure if the light color is stored as a 4-vector or 3-vector.

Ideally, the end result would be that I could have two objects that emit two different types of light. For example, one object emits Type A light and one emits Type B light. You place the objects in front of the special material, and one can be seen in the reflection, while the other can be seen on the other side of the material.

Note, that I don’t want to filter along RGB color values of light, that is not an option here.

Any progress with this?

no, unfortunately I haven’t had time. so far the only thing I can think to do is to create a material that is transparent, blended with a “reflection” type render target texture. i suppose if i wanna make something like this it would have to be in a low-level shader in the engine source code?