Parallaxing BG

public Transform[] backgrounds; // Array (list) of all the back- and foregrounds to be parallaxed
private float[] parallaxScales; // The proportion of the camera's movement to move the backgrounds by
public float smoothing = 1f; // How smooth the parallax is going to be. Make sure to set this above 0

private Transform cam; // reference to the main cameras transform
private Vector3 previousCamPos; // the position of the camera in the previous frame

// Is called before Start(). Great for references.
void Awake () {
// set up camera the reference
cam = Camera.main.transform;
}

// Use this for initialization
void Start () {
// The previous frame had the current frame's camera position
previousCamPos = cam.position;

// asigning coresponding parallaxScales
parallaxScales = new float[backgrounds.Length];
for (int i = 0; i < backgrounds.Length; i++) {
parallaxScales[i] = backgrounds[i].position.z*-1;
}
}

// Update is called once per frame
void LateUpdate () {

// for each background
for (int i = 0; i < backgrounds.Length; i++) {
// the parallax is the opposite of the camera movement because the previous frame multiplied by the scale
float parallax = (previousCamPos.x - cam.position.x) * parallaxScales[i];

// set a target x position which is the current position plus the parallax
float backgroundTargetPosX = backgrounds[i].position.x + parallax;

// create a target position which is the background's current position with it's target x position
Vector3 backgroundTargetPos = new Vector3 (backgroundTargetPosX, backgrounds[i].position.y, backgrounds[i].position.z);

// fade between current position and the target position using lerp
backgrounds[i].position = Vector3.Lerp (backgrounds[i].position, backgroundTargetPos, smoothing * Time.fixedDeltaTime);
}

// set the previousCamPos to the camera's position at the end of the frame
previousCamPos = cam.position;
}