Possible reflections solution (non-ssr). Need comment from Epic

General Feedback & Requests
1

Hello,

I would like get a status update from the Epic team if possible… do we have anything in the works for realtime reflections that are not screen-space?

I was recently playing (or I should probably say studying) assasin’s creed black flag and I noticed something interesting:
http://www.mediafire.com/convkey/b042/r8bm4kab29q32ruzg.jpg?size_id=5

Notice how the reflection of the sails do not match (not only they are the (default) color white but it also reflects another sail that is supposed to be folded).
That must mean that they are using some kind of per-object precaptured reflection map system.

So my question is: is something like that viable in UE4?
I would imagine that this wouldn’t work well with animated meshes (for example characters) but hey… one step at a time.

Reflections is one of the top “missing” rendering features in UE4 (in my opinion), it’s a problem in deferred rendering that needs to be solved eventually… SSR is not the solution.
SSR works fine if a particular scene does not need high quality reflections and if the player does not have full control over the camera (for movies and archviz fly-through for example) but in actual gameplay it can be pretty much unusable in many situations, not to mention SSR doesn’t work with FXAA (which is our only option if we want to avoid the blurriness and ghosting artifacts of TemporalAA but that’s another story).

2

Hi Tk-Master,

This is a known issue and something that can hopefully be resolved in the future. Daniel Wright has spoken about this on a couple of the Thursday Twitch Streams when the question has come up. At the moment, there isn’t a definitive time frame for when this will be investigated and implemented. I don’t have the link to that particular stream readily handy, but from what was said, there are some challenges to implementing the feature and it’s something that can hopefully be improved in future.

As far as workarounds and alternative implementations there are two that may be useful in your situation.

In the Making of Bullet Train stream Ryan Bruck’s shows how some of the reflections were done for the ad signs that could potentially work in your situation. I’ve linked at the approximate time where he discusses that technique.

Additionally, in older games where reflections were too expensive, you could simply mirror your asset to get reflections. In some instances of this you would use a lower poly version since it is only a reflection and doesn’t have to be 100% accurate.

I hope this helps.

Tim