This seems way harder than it should be, since all games use a view distance, and most have some kind of fog or something that will obscure objects without obscuring the skybox.
Volumetric fog works, but obscures the skybox; supposedly it doesn’t work great with transparent materials either, but I didn’t test it.
There is no universal view fade that I could find. There are fades for things like ambient occlusion, but that isn’t the same thing.
It’s really dumb, and maybe I went about it wrong, but I was able to produce a material that will fade a color over objects at a certain distance. I’m using this with HISMs, so I set the culling distance on the HISMs to be within that range of the “fog”. And I set the color of the fog to be as close to the ambient/skybox color as I could.
The problem is that to use this I have to put the material on a plane that is attached in front of the player camera (I moved it forward on the local x, and flipped it 90 degrees on the y).
Not sure if this is helpful to anyone else, but I’ll post the guts of it all here.
This is the material. It has a few parameters that are labeled with what they do.
Here is the plane attached to the player camera. note the location and rotation.
Here is an example of the “fog” fade. You can tell the blues don’t match exactly, but it’s close enough for me at this point.
You can’t really tell in the picture, but the pathway in the distance is made of multiple generic objects, and they do cull in the fog.
Here it is again with yellow fog instead.
I’m sure there are ways to shorten the fade distance so it’s more of a wall, but I haven’t figured that out yet.
I haven’t noticed any reduction in performance, but I don’t know how expensive this method is either.
I think you could use scene depth with this to have it only affect specified objects, but I haven’t messed with that either.
This is the KB page that I used to figure out the stuff I did.
Depth Expressions | Unreal Engine 4.27 Documentation