Firing at random intervals

[DarkArchonLord]

I am working on a top-down wave-based space fighter. I am trying to figure out how to get the current wave of enemies to shoot bullets at the player at random intervals so its not like a volley of bullets at the same time. The problem is there are different enemies on screen at the same time so i cant do something like "every 00-19 -> Unit_Enemy shoot Bullet in direction (down)" any suggestions?

[Corentin]

Use Alt Values :
Always set Alt Value Timer to Timer-1

When Timer = 0 Shoot and Set Alt Value Timer to Random(x)

PS : Note this Timer counts ticks, not seconds or miliseconds, this is frame-rate dependant.

[Blizna]

Or simply (time denendant):

-every 0,25s -> Set Alt value A of Enemy to Random(3).

A=1 -- Shoot, set A=0

So the greater range of random numbers you choose, the less chance the enemy will shoot.

[stuckboy]

I'd not recommend using the every (time period) condition because if the game engine slows down because of heavy loading on the CPU then the bullets will still come out at the same rate, meaning not only will people with slow computers have to deal with a choppy frame rate, they will also have more bullets coming at them, which isn't really fair!

Oh and also, when you set the counter to a random value, probably best to use a random and non random term e.g. 30+random(20) otherwise the enemies can possibly shoot out a whole lump of bullets at once. It's good for gameplay if you let the bullets firing have a little bit of predictability to them, that way the player can time his moves better.