Scroll 2d Background

Done_BGScroller.cs

using UnityEngine;
using System.Collections;

public class Done_BGScroller : MonoBehaviour
{
    public float scrollSpeed;
    public float tileSizeZ;

    private Vector3 startPosition;

    void Start ()
    {
        startPosition = transform.position;
    }

    void Update ()
    {
        float newPosition = Mathf.Repeat(Time.time * scrollSpeed, tileSizeZ);
        transform.position = startPosition + Vector3.forward * newPosition;
    }
}

OffsetScroller.cs

using UnityEngine;
using System.Collections;

public class OffsetScroller : MonoBehaviour {

    public float scrollSpeed;
    private Vector2 savedOffset;

    void Start () {
        savedOffset = renderer.sharedMaterial.GetTextureOffset ("_MainTex");
    }

    void Update () {
        float y = Mathf.Repeat (Time.time * scrollSpeed, 1);
        Vector2 offset = new Vector2 (savedOffset.x, y);
        renderer.sharedMaterial.SetTextureOffset ("_MainTex", offset);
    }

    void OnDisable () {
        renderer.sharedMaterial.SetTextureOffset ("_MainTex", savedOffset);
    }
}

StripScroller.cs

using UnityEngine;
using System.Collections;

public class StripScroller : MonoBehaviour {
    
    public float scrollSpeed;
    public float tileSizeZ;

    private Vector2 savedOffset;
    private Vector3 startPosition;
    
    void Start ()
    {
        startPosition = transform.position;
        savedOffset = renderer.sharedMaterial.GetTextureOffset ("_MainTex");
    }
    
    void Update ()
    {
        float x = Mathf.Repeat (Time.time * scrollSpeed, tileSizeZ * 4);
        x = x / tileSizeZ;
        x = Mathf.Floor (x);
        x = x / 4;
        Vector2 offset = new Vector2 (x, savedOffset.y);
        renderer.sharedMaterial.SetTextureOffset ("_MainTex", offset);
        float newPosition = Mathf.Repeat(Time.time * scrollSpeed, tileSizeZ);
        transform.position = startPosition + Vector3.back * newPosition;
    }
    
    void OnDisable () {
        renderer.sharedMaterial.SetTextureOffset ("_MainTex", savedOffset);
    }
}