unity2dでフェードアウトフェードインを作りたい

Unityで始めるc＃という本を読みながら脱出ゲームを作っています。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class GameManeger : MonoBehaviour {
    public const int WALL_1 = 1;
    public const int WALL_2 = 2;
    public const int WALL_3 = 3;
    public const int WALL_4 = 4;
    public const int WALL_5 = 5;
    public const int WALL_6 = 6;
    public const int WALL_7 = 7;
    public const int WALL_8 = 8;
    public const int WALL_9 = 9;
    public const int WALL_10 = 10;
    public const int WALL_11 = 11;

    public GameObject panelWalls;

    private int wallNo;

    // Use this for initialization
    void Start () {
        wallNo = WALL_1;
    }

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

    }

    public void PushButtonRight(){
        wallNo++;
        if (wallNo > WALL_11){
            wallNo = 1;
        }
        DisplayWall();
    }

    void DisplayWall(){
        switch (wallNo) {
            case WALL_1:
                panelWalls.transform.localPosition = new Vector3(0.0f, 0.0f, 0.0f);
                break;

            case WALL_2:
                panelWalls.transform.localPosition = new Vector3(-2000.0f, 0.0f, 0.0f);
                break;

            case WALL_3:
                panelWalls.transform.localPosition = new Vector3(-4000.0f, 0.0f, 0.0f);
                break;

            case WALL_4:
                panelWalls.transform.localPosition = new Vector3(-6000.0f, 0.0f, 0.0f);
                break;

            case WALL_5:
                panelWalls.transform.localPosition = new Vector3(-8000.0f, 0.0f, 0.0f);
                break;

            case WALL_6:
                panelWalls.transform.localPosition = new Vector3(-10000.0f, 0.0f, 0.0f);
                break;

            case WALL_7:
                panelWalls.transform.localPosition = new Vector3(-12000.0f, 0.0f, 0.0f);
                break;

            case WALL_8:
                panelWalls.transform.localPosition = new Vector3(-14000.0f, 0.0f, 0.0f);
                break;

            case WALL_9:
                panelWalls.transform.localPosition = new Vector3(-16000.0f, 0.0f, 0.0f);
                break;

            case WALL_10:
                panelWalls.transform.localPosition = new Vector3(-18000.0f, 0.0f, 0.0f);
                break;

            case WALL_11:
                panelWalls.transform.localPosition = new Vector3(-20000.0f, 0.0f, 0.0f);
                break;
        }
    }
}

パネルを１１枚作っていて、クリックすれば次のパネルになるように作っています。そこで次のパネルに移る時にフェードインフェードアウトをしたいのですがどうすればいいでしょうか？
またもうちょっとコードを短かくかける方法があれば教えていただけたら嬉しいです。よろしくお願いします。