Using variable to change materials?

So I have a question: Lets say I have a bunch of materials that need to change based on certain conditions.

Example: The player walks into a room and is holding a specific object, so lets say HoldingTorch = true. All of the materials in the room should swap to a different diffuse texture (or something like that). Or maybe something like a detail texture can be layered on. Like everything becomes moldy. I’m not really sure how I would actually do it, but that’s the effect I’m going for.

I’m still pretty new to Unreal so sorry for the noob question.

Any Ideas?

It’s a great question, actually.

What you’re talking about is the Material Parameter Collection - a powerful, yet underused feature of the engine.

Think of it as a set of global variables many materials can tap into.