I recall an early gas giant atmospheric "proof of concept" in the background of one of David Braben's early development videos that had clouds based on billboards to give an idea of what I'm waffling on about.
Always wondered whether that was one of FDev's own experiments, or just video of somebody else's shader. (...may have been included in a TED talk David did about procedural generation, too, IIRC...)
I set up some different tracking billboards doing some "fan made levels" for a game, years ago; That engine simply gave me a bunch of flags which let the level designer lock or link axes to their heart's desire, so I could e.g. have a simple "aura" type overlay with additive mixing hovering in front of a light fitting, from the vantage point of the camera, but also a wavy laser beam sort of thing, that would only track-rotate around its lengthwise axis. Alas the fan-made Blender-based level export scripts didn't support particle systems at the time, so I never got to play around with those. :7
Personally, I find regular billboards perfectly acceptable in VR, for a ton of smoke style effects, if done right -- even the massive single-quad steam cloud that sometimes occupy the entirety of a landing pad can look just fine to my eyes, if I just keep perfectly still -- it's the particular screen sprite behaviour that makes the illusion break down completely for me.
The reason I am not convinced no builds of the engine have had the facilities to do it "right", can be seen on a local star, which has this huge flare overlaying it, which rolls along with your ship/head (...and swivels up/down and to the sides, too, which actually
makes it so that one see the quad kind of edge-on, when it is out in one's periphery, whether it is a sun flare, or some steam from a geyser, or whatever, given it is always parallel with the viewplane, instead of facing the viewpoint), in just that way which some of us find so annoying; But
behind the star, there seems to be another, very similar but smaller billboard (wouldn't be surprised if it uses the exact same texture), which paints an effect mimicking the star's corona (it becomes more visible if one occlude the centre of the star, so that the flare stops rendering), and that one does
not roll with the camera - it stays put with the star, but still always faces the camera. Even if these two do not share a common billboard rendering subsystem, it seems obvious-ish that the capability is in there
somewhere...
We also have Arioch's swearing blind that he recalls a past when the smoke that appears over one's ship's dashboard when the ship overheats, didn't exhibit the ugly rotating behaviour it does today. :7
EDIT: I'll not deny a lot of large layers of overlays like this can take a toll on performance, mind you, after experiencing some rather noticeable slowdowns whilst passing through the belching smoke from the heat vents of an overheating Thargoid Titan.
Those appeared to have normal maps to their texturing, dealing with lighting on the debris in the texture, much like small rocks and stuff in a ring/asteroid system, which would add some overhead of its own, I guess.
