You haven't explained really what you're trying to do, I'm guessing you're creating a racing game or similar and want to know only the players position

If I'm right so far you can try something like

Code:
function position_check(ENTITY* ent){
	//me = ???;
	if(vec_dist(my.x, endpoint.x)) < vec_dist(ent.x, endpoint.x)){
		return(1);
	}else{
		return(0);
	}
}

function update_position(){
	while(1){
		position = 1;
		position += position_check(ai1);
		position += position_check(ai2);
		wait(1);
	}
}

I haven't tested any of this, it's really only for guidance
You'll need to set what me is in the 1st function, and repeat position += position_check(ent_name) as necessary for any additional opponents

Hope this helps