Unity 2D Horizontal Sprite Scroller

ScrollingBackground.cs

using UnityEngine;
using System.Collections;

public class ScrollingBackground : MonoBehaviour {

	// Here's what this script does, step by step:
	// Duplicates the object
	// Scrolls both at a given scrollSpeed
	// When an object's full length has been scrolled, it is placed on the duplicate's original position
	// Last step is repeated for both objects indefinitely

	public float scrollSpeed = 0.5F; // Scroll speed in units per second
	
	private Vector3 originalPosition;
	private float originalXPosition;
	private float maxX;
	private float minX;
	private float spriteWidth;
	private bool isDuplicate;

	private GameObject duplicate;

	void Start () {

		// Get this object sprite's width and X position

		spriteWidth = GetComponent<SpriteRenderer>().sprite.bounds.size.x;

		originalPosition = transform.position;

		originalXPosition = transform.position.x;

		if (!isDuplicate) {

			// Set the max and min X values (the duplicate has these passed to it)

			maxX = originalXPosition + spriteWidth;
			minX = originalXPosition - spriteWidth;

			// Instantiate a duplicate of this object on its right

			Vector3 duplicatePosition = transform.position;

			duplicatePosition.x += spriteWidth;

			duplicate = (GameObject) Instantiate(gameObject, duplicatePosition, Quaternion.identity);

			// Tell duplicate to not duplicate itself
			duplicate.GetComponent<ScrollingBackground>().DefineAsDuplicate(minX, maxX);
		}

	}

	void Update () {

		// Wait for duplicate to be instantiated
		if (!isDuplicate && !duplicate) {
			return;
		}

		float offset = Time.deltaTime * scrollSpeed;

		float newX = transform.position.x;

		newX -= offset;

		if (newX <= minX) {

			// Move sprite forwards

			// Assume we have overshot minX and add difference to offset
			offset += minX - transform.position.x; 

			Vector3 newPosition = originalPosition;

			newPosition.x = maxX - offset;

			transform.position = newPosition;
		
		} else {

			// Move sprite backwards

			Vector3 newPosition = transform.position;

			newPosition.x -= offset;

			transform.Translate(Vector3.left * offset);
		}
		
	}

	void OnDestroy () {

		Destroy(duplicate);
	}

	// Called if this instance is the duplicate
	public void DefineAsDuplicate (float minX, float maxX) {

		// Prevent creation of another duplicate

		this.isDuplicate = true;

		if (duplicate) {

			Destroy(duplicate);
		}

		this.minX = minX;
		this.maxX = maxX;
	}

}