It seems that a trace for every shot of a fast machine gun will make the game rather slow.
Does anyone know how "professional" games do it?
A trace for every 10 shots...?

Or how would you do it?

well... i create a tracer per shot.. but you can probably do random(10)+2 to determine when to spawn a tracer, the speed of which the tracer moeves has alot to do with how it'll look though.. i think games like call of duty create a tracer for like every 8 shots or so...

it shouldnt slow you game down too much... just dont use c_move to move your tracers

other thing you can try is make the trace shorter so it scans less entity's

he means tracers and not the actual c_trace

c_trace is not as slow as you think, for a machine gun it's just a trace every few frames... You probably can do 100 traces per frame and a normal pc wouldn't slow down too much. Just try it out!

edit: ofc the speed of trace execution relies on it's length and the level complexity in this area of the level

edit2: did a small test

100 random traces inside a box of 1000³ with 400 boxes inside per frame still give me 60fps

For my machinegun I just use vector mathematics to calculate a start position and an end position and then c_trace between them both. It's the fastest way to do it.

wow, lots of answers.
Okay, first:
I am using c_trace atm. Darkinferno, i don't know what you mean by "tracer"... can you explain?
Scoprion, thanks a lot for testing that. I think in my case, the slowing down has to do with level complexity.
I don't want to post a screenshot of my level atm, because we're planning to post a big post with infos and videos soon and want it to be a surprise, but we have a loooot of asteroids in the level. All models, all polygon-collision. I would like to put some of the asteroids to box collision or entirely passable if they're outside the ship's weapon range, but the tracing is done serverside atm, for speed and anti-cheating reasons. That means that I have to make the asteroids around every player non-passable, and with the computing that is needed to check the distance of every asteroid every frame to every ship, I think I'm better off not doing it at all.

Redeemer: I do the same atm. Have you tested what happens when 10 players (or bots) fire a machine gun at the same time? Do you trace for every shot? What firing rate does your gun have?

Flits: That is an idea, and I believe it would work, to make the trace shorter, but I can't. if I decrease the weapon range any more, it'll be weird and hard to hit enemies in a space shooter.

oh, sorry germanunkol, i thought you already wrote the code for shooting and was just trying to set up the bullet tracer visual effect that the players would see.. i really dont see why c_trace should slow you game down that much though, especially since the server wont be handling shaders, just shooting and sending positions i assume... in my scion tps demo, here: scion tps gameplay video all weapons are c_trace weapons and notice how many shots you see being done, every bullet fired was a c_trace, and each enemy and player traced to the ground alot to help with movement and it ran very fast though not optimized in any way

Hm. Okay...

Well, the visual effect pretty much works. It's not perfect, but it'll do for now. It's the c_trace I'm worried about. And really, it doesn't slow down the game to an unplayable state, but it does slow it down from 75 fps if nothing hits to 60 fps if something hits. But if you all say that it's not that slow, maybe I should check if it's the bullet-impact-effects that slow down the game...