Fog Actors

Is there a proper fog actor implementation planned for the future?
It’d be cool if the interior of a house is clean, and the attic is foggy/ full of dust or something like that.
Light Shaft Scattering with Spot/ Point lights would be awesome, too. That would create some spooky effects.

We have to see what they’d come up with once volumetric fog is done. Probably currently WIP.

This would be great and useful in so many cases!

Hey everyone,

As always, thank you for your feedback! I just wanted to let you all know I was taking more notes about this FR as you’re talking about it. If there is anything specific that you want feature-wise with volumetric fog and fog rendering, just drop it in here.

this is awesome news :slight_smile:

What about a customizable “mask” that changes the density of the fog via material?

I’m someone who has only gently dabbled with UE4 so far because I’ve been waiting for volumetric fog. I had no real sense of how long I’d be waiting and I realise that the roadmap hasn’t been updated for a while so it may be out of date and I won’t presume July is still accurate, but it was at least very nice to see volumetric fog get assigned a timescale. And now to see this thread and the request for feature requests :slight_smile:

I suppose I kind f wanted to get a sense of what sort of system Epic have planned before getting into my requests and hopes in detail, but since the opportunity arises here I guess I will just spill my brains out now. Apologies if I fail to use correct Unreal Engine terminology at any point along the way, I’m still a novice with this engine.

I’m hoping it will be a system based on the popular modern technique. Using Voxels aligned to the camera frustum or whatever its called. Featuring all the eye-candy that this technique offers, including very nice light-shafts/shadows in the fog.

With support for all light types, including area lights and emissive textures.

And suitably well disguised fallback to a cheaper fog system at greater distances if thats what this technique needs for performance reasons (I forget).

The ability to have an animated 3d noise texture(s) affecting fog density. Globally or within a defined region of the level.

The ability to affect fog density in specific locations using particle systems.

Physically based type settings (e.g. atmospheric variables) but also perhaps the ability for some art-driven overriding. Hard to get into detail on this without knowing what the systems foundation is going to be like really.

Thanks for listening. I’m not exactly anticipating getting all of the above with the first version of the volumetric fog but I’m certainly hoping its based on the modern technique and can gain most of the above features over time. I’d also want it to integrate well, or even be part of the enabling technology for, visual stuff that goes on ‘higher in the sky’ but again I don’t think there is much point me stumbling around trying to explain myself more on that one until we have some sense of what volumetric fog we are getting and how well its integrated with lighting systems.

Hey SteveElbows,

I really like your enthusiasm and inquiry about this feature we plan to implement. Unfortunately, I do not have any inside information on the techniques or ways we plan on implementing the Volumetric Fog effect. While your inquiries are valid, I think it best to wait to see the feature in engine first so we can get an idea of how it will be implemented and its associate rendering features and techniques. With that said, there are a some ways to fake volumetric lighting and fog which provide a convincing look to the untrained eye. Using Light Propogation Volumes in conjunction with Light Shafts, God Rays, and a Post Process Blendable material that has an animated fog like effect can really give you a convincing look.

As always we appreciate our users input in regards to improving the quality of features or adding new features into the engine. It is just going to take a little time and patience to see what the Volumetrics have to offer before we can begin making requests on how we wish it to function.


Andrew Hurley

Thanks very much!

However I have to say that parts of your response read like you missed the post by [MENTION=8]Alexander Paschall[/MENTION] earlier in this thread, which is what motivated me to splurge out my thoughts here now despite it being early days for this feature.

Can probably take an educated stab at what the new volumetric fog will entail. Can look forward to animated fog with density control, quite probably individual fog volumes (actors) with controllable parameters if not at launch then at some point after it, volumetric fog being affected by any and all direct lights and shadow casting lights, and pretty decent performance. Using it for clouds is entirely possible, though may not make launch/have to wait for a community effort.

A fairly fast, robust, and stable way of doing volumetric shading coalesced in the games industry around last year. And while Epic might experiment some, a lot of it is robust and universal and so not going to hold a lot of surprises. The good news is of course that it’s quite flexible and fairly fast, can probably extend to other types of particles such as smoke with some effort, and can even receive indirect lighting (depending on how Epic ends up doing that).

Personally, more than volumetric fog, I would like to see something along the lines of a fog volume. Something you can place in the level and change the shape the same way you would edit BSP, and only inside that volume actually has the fog in it. The idea being, instead of having a massive, level spanning fog actor, it can be more localized to certain parts of the level if needed. I could also see a spherical fog volume being useful for when the BSP editing style would be difficult to get a nice, round corner on it. If possible, having a configurable falloff when the fog nears the edge of the volume would be nice as well to get a smooth transition.

Just wanted to let you know that we are indeed listening to our users requests in relation to the feature’s implementation and appreciate your feedback and ideas. With that said, I have gone ahead and updated the already entered Feature Request, UE-2254, with some of the specifics mentioned in regards to its implementation.


Andrew Hurley

Excellent, thanks very much indeed! Time for me to start getting into UE4 properly so that when the time comes I’m not stumbling around with engine basics!

Ah, I see the roadmap has just been updated and Volumetric Fog has gone back to being labeled as backlog again :frowning: