Inserting joystick support to rigidbody controller

I have the following code and I'm trying to input virtual joystick support but i don't know how to given the fact that i have to define two directions to one joystick var speed = 10.0; var gravity = 10.0; var maxVelocityChange = 10.0; var canJump = true; var jumpHeight = 2.0; var moveJoystick : Joystick; private var grounded = false;

 @script RequireComponent(Rigidbody, CapsuleCollider)
 
 function Awake ()
 {
     rigidbody.freezeRotation = true;
     rigidbody.useGravity = false;
 }
 
 function FixedUpdate ()
 {
     if (grounded)
     {
         // Calculate how fast we should be moving
         var targetVelocity = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
         targetVelocity = transform.TransformDirection(targetVelocity);
         targetVelocity *= speed;
         
         // Apply a force that attempts to reach our target velocity
         var velocity = rigidbody.velocity;
         var velocityChange = (targetVelocity - velocity);
         velocityChange.x = Mathf.Clamp(velocityChange.x, -maxVelocityChange, maxVelocityChange);
         velocityChange.z = Mathf.Clamp(velocityChange.z, -maxVelocityChange, maxVelocityChange);
         velocityChange.y = 0;
         rigidbody.AddForce(velocityChange, ForceMode.VelocityChange);
         // Jump
         if (canJump && Input.GetButton("Jump"))
         {
             rigidbody.velocity = Vector3(velocity.x, CalculateJumpVerticalSpeed(), velocity.z);
         }
     }
     
     // We apply gravity manually for more tuning control
     rigidbody.AddForce(Vector3 (0, -gravity * rigidbody.mass, 0));
     
     grounded = false;
 }
 
 function OnCollisionStay ()
 {
     grounded = true;    
 }
 
 function CalculateJumpVerticalSpeed ()
 {
     // From the jump height and gravity we deduce the upwards speed 
     // for the character to reach at the apex.
     return Mathf.Sqrt(2 * jumpHeight * gravity);
 }