var trigger_running = 0;
var player_moving   = 0;
void trigger_physic (ENTITY* ent){
   if (trigger_running || !player_moving) return;
   if (!ent) return;
   trigger_running = 1;
   var _dist  = 35;
   var _ndist = 0;
   for (you = ent_next (NULL); you; you = ent_next (you)){
    	_ndist = vec_dist (ent.x, you.x);
    	if (_ndist < _dist){   	   
    	   _dist = _ndist; 
           VECTOR xspeed; // main stuff
           vec_set    (xspeed, vector(200 * time_step, 0, 100 * time_step));
           vec_rotate (xspeed, ent.pan);
           pXent_setvelocity (you, xspeed);     	   
    	}
   }
   trigger_running = 0;
 }

...
while (...){
   if (key_w || key_a || key_s || key_d) player_moving = 1;
   else                                  player_moving = 0;
   c_move ( player ... );
   trigger_physic (player);
   wait (1);
}
...