Global movement

Hello! i have a script that moves my character relative to the camera, it works well, as it works while the camera rotates, but my character is always facing a single direction, so a part of the code changes his rotation, and the problem starts with this, and i think it's caused because the script moves my character in local coordinates, so when the character rotates it changes the way it moves in a weird way. So my cuestion is, How do i move my character independetnly of it's rotation using global coordinates?

This is the script

 var dir: Vector3;
 var direction: Vector3;
 
 var speed : float = 2.0;
 var gravity : float = 30.0;
 
 var vertical :Vector3;
 var horizontal:Vector3;
 
 var total: Vector3;
 
 private var moveDirection : Vector3 = Vector3.zero;
 
 function Start () {
 
 }
 
 function Update () {
 var cam : Transform = Camera.main.transform;
 
 var controller : CharacterController = GetComponent(CharacterController);
 
 var cameraRight : Vector3 = cam.TransformDirection (1, 0, 0);
 var cameraFord : Vector3=cam.TransformDirection(0,0,1);
 
 vertical = cameraFord* Input.GetAxis("vertical");
 horizontal = cameraRight* Input.GetAxis("horizontal");
 
 
 total = vertical + horizontal;
 
 moveDirection = total*0.5;                        
             moveDirection = transform.TransformDirection(moveDirection);
             moveDirection *= speed;
             
 //transform.rotation = Quaternion.LookRotation(total);            
 
 
 moveDirection.y -= gravity * Time.deltaTime*5;
 
 controller.Move(moveDirection * Time.deltaTime);
 
 }

The line which changes the rotation is the one in a comment, and the script works well while this line is in a comment but my character is always facing to the same direction.

Any help would be appreciated. Thanks in advance!!