How do I fix my script?

I have a code that makes a target UI Image rotate in the direction of the movement axis. Here's the script...

Code (JavaScript):

1. var Arrow : UnityEngine.UI.Image;
2.  
3. function Update () {
4. if (Input.GetAxis("Horizontal") < 0){
5. Arrow.transform.rotation = Quaternion.Euler (0, 0, 90);
6. }
7. if (Input.GetAxis("Horizontal") > 0){
8. Arrow.transform.rotation = Quaternion.Euler (0, 0, -90);
9. }
10. if (Input.GetAxis("Vertical") < 0){
11. Arrow.transform.rotation = Quaternion.Euler (0, 0, 180);
12. }
13. if (Input.GetAxis("Vertical") > 0){
14. Arrow.transform.rotation = Quaternion.Euler (0, 0, 0);
15. }
16.     }

But, the problem is, it only rotate's it to those 4 angles. How would I make it rotate to all 360 degrees and not just -90, 0, 90, and 180?

 

The only thing I could think of would be to increment the rotation by the Input.GetAxis() value. Since Input.GetAxis() returns a number between 0 and 1, you could multiply it by a speed variable, and then rotate it in increments every frame. I'm really new to this, so the code is probably all messed up. But hopefully it will give you some ideas on how to work out this problem.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Test : MonoBehaviour {
5.  
6.     public float rotationSpeed = 2.0f;
7.  
8.     // Use this for initialization
9.     void Start () {
10.    
11.     }
12.    
13.     // Update is called once per frame
14.     void Update () {
15.         float verticalPos = Input.GetAxis ("Vertical");
16.         float horizontalPos = Input.GetAxis ("Horizontal");
17.         verticalPos *= rotationSpeed;
18.         horizontalPos *= rotationSpeed;
19.         Arrow.transform.rotation = Quaternion.Euler (horizontalPos, verticalPos, 0);
20.     }
21. }

 

maybe use quaternion.slerp
http://docs.unity3d.com/ScriptReference/Quaternion.Slerp.html

Code (CSharp):

1. Arrow.transform.rotation = Quaternion.Slerp(Arrow.transform.rotation, Quaternion.Euler(0,0,90), Time.deltaTime * speed);