protected virtual void FixedUpdate()
 {
     if (tracker != null)
     {
         tracker.FixedUpdate();
     }
     else
     {
         if (!noTrackOverride)
         {
             throw new UnityException("Pojectile " + this.ToString() + " has no track. and cannot do physics update.");
         }
     }
 }
 protected virtual void FixedUpdate()
 {
     track.FixedUpdate();
 }