Shader global booleans

Hi, I’m a relatively new programmer looking to find what classes in the engine are responsible for global build time bool operations on multiple shaders. The best example of this is ForceFullyRough

This is a Boolean that is featured on every material in UE4 however what I’m interested in is its ability to be added to the Android .ini and when compiling shaders for gles3.0 the shaders will be fully rough. It would be incredible if someone could tell me how to create my own Boolean like this in the engine for metallic or even occlusion. I know this may not be good practice, it may even be detrimental to my project but this is simply a test for myself to gain a better understanding of how these properties are made/ how and when they interact with the shaders.

I understand this may be a simple question with appreciatea complex answer but if you have the time, I’d greatly appreciate it :slight_smile: thanks guys.