[Twitch] UE4 Rendering - Apr. 9, 2014

Hi everyone, we’ll be hosting our next Twitch broadcast to provide direct access to Epic’s rendering leads.

We invite you to submit questions, give feedback and tell us what you want to discuss here in this thread!

When: Wednesday, April 9, 10:30 a.m. PDT / 1:30 p.m. EDT / 6:30 p.m. BST
Who: Nick Penwarden, Lead Rendering Engineer + Martin Mittring, Sr. Graphics Architect
Location: (live from Epic HQ)
Topics: Rendering features we think you should know about, up-and-coming features, anything else you want to know

Post away! Look forward to seeing you soon.

REALLY need to have some discussion about custom lighting support and improved reflections on translucent surfaces. I’ve been fighting with my water shader all day :frowning:

EDIT: A few things on my mind:

  • Support for Normal Maps with Alpha Channels
  • Support for ‘Uncompressed’ texture formats
  • Ability to specify the unpack min and max values for textures (I’m using a bias scale in my shader right now).
  • Improvements to specular reflections on transluscent surfaces, current implementation is pretty shocking for large exterior water bodies, or glass etc.
  • Allow us to bake Emissive lighting into lightmass again
  • Bring back custom lighting! For those that don’t strictly want to use the PBR model.
  • Give particle lights the ability to light other particles. (Apparently this has already been done, but it’s not public yet?).
  • Bring back the old-school Distortion for materials as an alternative to refraction, especially useful for particle systems and other effects.

Sorry, turning into a feature request post :P. Hopefully this will get some minds thinking!

I would like a more detailed table of features available for different types of processors/devices. It’s easy to go nuts on the desktop and find out it looks completely different in mobile.

Will area lights make it back into UE4?

Features I’d like to see:

  • Skin shader [SSSSS per object + translucency]

  • Eye shader [iris parallax + highlight]

  • Hair shader [soft masking + anisotropic highlights]

  • Water shader [real-time reflections on translucent materials]

  • Volumetric lights [not screen space]

Ill be there again!

As for shaders, I have messed around with displacement shaders, but still I don’t think I’m using them to full potential. Could we simulate waves and such with this effect, and how to go about it?

I’m also interested in simulating water caustics. Would that just be a material thing?


Yeah I’m one of the guys who struggle with water shaders as well… it would be great if we get some kind of answer of when will we get any improvements on translucent materials etc.

Also (and I’m not sure if this is specifically related to rendering but…) are there any future plans of integrating something like nvidia’s WaveWorks & FLEX into UE4?

What are you thoughts on dynamic shadows on mobile? Is this feasible? I’ve seen some games pull it off (possibly with only one dynamic light per scene).

Oh and the return of some of the missing Cascade modules would be awesome too, Size Scale by Time, Size by Velocity to name a few.

I’m curious what the rendering leads’ biggest headaches have been. If they could close there eyes and the community could crank out something, what would it be? :slight_smile:


I can’t attend the live stream, so I’ll watch later. If possible i’d like to see some points touch on Arch Viz render setups, or great Tips would do too, leaving room for other topics.

Thank you!

Are there plans to improve the (already quite nice) decal system? I’ve been struggling to get it to behave “properly” in areas that are not lit directly, as seen here:
(EDIT: apparently the lighting problem has been fixed already, thanks!)

Also the bleeding onto objects other than the decal actor’s parent is sometimes undesirable. I’m not sure if this can be fixed with the current deferred decal method. I’ve been trying to understand the decal renderer, but I got lost in all the rendering code. Speaking of which, a general overview or crashcourse on Unreal’s rendering architecture and Unreal specific things would be nice too, if it fits the style of the livestream.

One of the engineers on the rendering team put this together:

You might find it useful.

More light hearted question: Why does the editors highlight around selected objects like a box for example it “wiggles”. on some edges as the camera is sitting still Always wondered about that since I first opened the editor. (Perhaps its just me)

Is PBR(Physically based rendering) more efficient and should be used entirely if possible or less efficient and I should pick and choose were I want the extra realism.

You don’t have a choice… PBR is the ONLY rendering system available right now

lets hope its a bit less boring then last livestream. show more actual engine footage, deminstratons, tutortials, tips etc. more hands on stuff. not just sitting around talking about the engine for an hour. thats boring :-p.

Well, it was a livestream about an engine, what did you expect? There is plenty of footage around the web, I don’t think any one on here needs more marketing material, considering most people already are customers. What’s much more interesting is hearing about current development, new features and the future of the engine.

Some info on the state of the dynamic GI development would be nice :slight_smile:

I’d love to see someone comment on Texture Arrays (Or 3D Textures) in relation of using them with shaders to create near enough to limitless terrain painting.

A feature I’d like to see is a hair shader with anisotropic highlights. (Actually, I’d love to see a stand-alone hair system in UE4).