Just curious if an effect is possible, and if it is, how taxing it is.

Basically, I want 1 smoke cloud, to linger around, permanently. Not to render anymore, just one that lingers around over debris.

Got an idea for a map, however doubt I could create the ambience and atmosphere without this kind of effect.

Is there a less taxing effect? Smoke can be taxing especially on a system and the amount that I am after.

In my opinion, CSS does it best on de_dust2. If you look at the sky, you'll see dust clouds. Those are models and they wouldn't hurt your performance really bad.

Or you can try a func_smokevolume. In contrary to smokestack, it's brush based so you define its size more precisely, and it's not emitted beyond the size of the brush.

Seen as that also uses sprites, using that on a big brush will result in some tiling. So you may want to make your own texture to use for this. As with a smokestack, the more particles/sprites emitted, the bigger the overhead.

The main problem isn't the number of particles rendered at the same time per se, but z-rendering. In this case, multiple alpha layered being rendered front to back and the engine having to figure out in which order to show them, and what to render through the dust.

This is why you can sometimes use very cool effects with a single particle emitted, and not see a single fps drop. Works for a dudv-texture based heat effect on a fire for example.

yeah check dust and dust2 via entEd or entspy, iirc one of them uses both methods furyo's talking about (models above, smokevolume in the meat of the level)