Hey guys, happy Ascension day!
Today I devoted my day to bringing the Interior Mapping technique to Unreal Engine 4! 
For those that are not in the know, Interior Mapping is a technique to simulate virtual geometry with only a pixel shader. It’s been most recently used in Watch Dogs:
30/5 UPDATE
I’ve migrated the material function + sample textures and materials over into a new project, which you can download here:
InteriorMapping.rar
I’ve tried my absolute best to make it as lightweight as possible, but if you have any comments/additions/suggestions, you’re more than welcome! Enjoy!
One quick note: Due to the Unreal distance units, the tiling and room frequency parameter settings usually have very low values (0.015 is the default). I originally multiplied the parameters by a very small number, but because these floating point operations add more complexity to the shader, I’ve decided to leave them out altogether.
And, combined with a few very basic textures it looks like this:
