I'm creating some smoke effects that are emitted when I shoot, but I have trouble moving the vector in front of the player. Usually it ends up on 1 side only. Any formula or something to change this?

if you want us to change anything it would be good for us to know what it is we have to change.

Not that much code

temp.x=20;
temp.y=0;
temp.z=1;
vec_rotate(temp,camera.pan);
effect(effect_flame, 20, temp, nullvector);

is your camera always at the origin? have a look at vec_for_screen.

No, thats why I'm having trouble. Do you just add vec_for_screen(temp,camera); after all the vector changes? Cause It just seems to make it disappear.

don't use vec_rotate; afaik x and y need to be zero, while z has to be positive, like 200 or so. then use vec_for_screen.

You mean like this?
temp.x=0;
temp.y=0;
temp.z=200;
vec_for_screen (temp, camera);

It doesn't do anything right now, is there something else I forgot?

EDIT::
Nevermind, it works now. I just have some trouble placing it in the right spot.

EDIT::
I have another question. The particles keep going through the ground, what can I do to change this?

particles have no collision detection. use sprites or write your own one... i'd advise the first.

Alright, thanks