function effect_rocket_tail_fast(PARTICLE* p) {
	p.vel_x = you.x - p.x;
	p.vel_y = you.y - p.y;
	p.vel_z = you.z - p.z;
	vec_set(p.x, you.x);
}

function effect_rocket_tail(PARTICLE* p) {
	p.flags |= BEAM;
	p.bmap = raketen_schweif_tga;
	p.alpha = 45 + random(25);
	p.size = 50;
	p.event = effect_rocket_tail_fast;
}

action rocket() {
	effect(effect_rocket_tail, 1, my.x, nullvector);
	
	while (1) {
	...
	move and do some other stuff
	...
	}
}