We are creating mobile game with high end graphics and trying to achieve some kind of realtime reflections on mobile platform. Currently we are rewriting render core of UE4 and already added motion blur on mobile. Can you please advise us what is the best way to add realtime reflections on mobile with UE4?
Before we dive into mobile, you want real-time reflections. This does not exist, at all. Most engines have their own implementation of screen space reflections. Which is okay, but only reflects everything inside your screen. Everything else is baked reflections. Some engines update the baked reflections every x amount of seconds to make sure lighting stays correct in dynamic scenery.
If you do find a way to make everything reflect dynamically, you just found the holy grail of rendering, congrats!
You always have to take some short cuts, it really depends on what you want to achieve in the game. Is 90% a flat floor and is the game not too high poly, you might want to render a second camera upside down, like they do for mirros and water.
I created a static planar reflection once, because most objects were reflection a static floor beneath them, so calculations the plane of that floor inside the object to fake dynamic reflections was really accurate.