Shaping volumetric fog with geometry


I recently played “Inside” and the render techniques shown in this game are simply breathtaking and so I watched playdead’s GDC talk about how they rendered tose stunning environments.

They used boxes/brushes/meshes to define certain volumetric fog areas like you can see in this video:

I’d really like to see this in UE4 because currently I think it would not be possible to recreate a scene like the one shown in the video. I’ve already taken a closer look at the ability to limit fog to certain areas with particles but this is not the same because you can’t “fill” a defined volume with fog. Moreover you always get those “look at camera” billboard behaviour with the current implementation.

So could you please implement a feature for defining different fog areas with boxes/brushes/meshes?

Best regards,

Best way to achieve this would be to extend support for ‘Volumetric’ material types to non-particles. I don’t know how difficult that is though, or why it was restricted to particles in the first place.

I may have misunderstood, but this sounds doable with particles.
The fog samples the material of each particle for each voxel in space. This means you can define a 3d shape with some distance field math and it will be added as fog. A simple use case is a spheremask node to create a sphere, or a boxmask node to get an axis-aligned box.

That was possible even before the official 4.16 release (gif from around 3 months ago, using the master branch at the time) Screen capture - e9b6c8f8ba35d0252c27ee24c82327c0 - Gyazo (I’d also like to know why are particles only supported for now.)

I guess it’s because you need a ‘Volume’ to fill, just having a hollow box-brush wouldn’t work very well I assume. tbh if I wanted specific areas of density I’d probably do what Ryan Brucks does with smaller pseudo-volumes instead, or do the old-school way and use meshes and materials.