Procedural "SkyBox" texture

I’ve got idea I’d like to try in my project but I’m not sure what’s most proper way to do it. Basically I’d like to create cylindrical “skybox” consisting of black background and half-transparent color rectangles that would appear in fog at top of scene and fall down to disappear in fog at bottom. My only problem with that is creating procedural texture in way that wouldn’t hit performance too much. How should I proceed with that?

You could use a custom fragment shader.

I’m not 100% sure, but is it not possible to create a bunch of moving half transparent Quads and put them in the Skybox Renderbucket?

It depends on the quality of the effect you want to achieve. A coworker of me had this thing with procedural 3D fogs that calculated a “fog integral” - I did not look into it, but it sounded like an optimized raytracing effect. The fog clouds could even move around obstacles depending on a texture that an artist provided.

For the cheapest solution you would render a particle system to a quad or use a particle system directly (should not matter on modern graphics cards - I suppose the particle system is even faster). To optimize that you could use soft particles or “pseudo 3D particles” (every smoke particle is rendered as two triangles, but the normals are distributed in a 3D manner around the particle center).

This “nice volumetric fog” we are talking about here, is a difficult topic… (and I’m not inside of it now)

You can.
Those are 3 quads with shaders to rotate them and 6 BitmapTexts.