To have a way to fade in/out the screen with a color (u5.6)

PlaneFader.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;

/// <summary>
/// Author : https://gist.github.com/Legogo
/// 2017-05-15
/// </summary>


public class PlaneFader : MonoBehaviour {
  
  [RuntimeInitializeOnLoadMethod]
  static protected void create(){
    _manager = createCarrier<PlaneFader>("[fader]");
  }
  static protected PlaneFader _manager;
  static public PlaneFader get(){ return _manager; }

  Camera cam;
  Coroutine coProcess;
  Color nothing;
  Material planeMaterial;


  Color startColor;
  Color endColor;

  float fadeSpeed = 1f;
  float progress = 0f;

  void Awake()
  {
    transform.position = Vector3.up * 10000f;

    cam = gameObject.AddComponent<Camera>();
    cam.depth = 100;
    cam.farClipPlane = 10;
    cam.useOcclusionCulling = false;
    cam.enabled = false;
    cam.clearFlags = CameraClearFlags.Depth;

    nothing = new Color(0f, 0f, 0f, 0f);

    GameObject plane = GameObject.CreatePrimitive(PrimitiveType.Quad);
    plane.transform.SetParent(transform);
    plane.transform.localScale = Vector3.one * 100f;
    plane.transform.localPosition = Vector3.forward;
    
    MeshRenderer render = plane.GetComponent<MeshRenderer>();

    planeMaterial = new Material(render.material);
    render.material = planeMaterial;

    planeMaterial.SetFloat("_Mode", 3f); // transparent
    planeMaterial.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.SrcAlpha);
    planeMaterial.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);
    planeMaterial.SetInt("_ZWrite", 0);
    planeMaterial.DisableKeyword("_ALPHATEST_ON");
    planeMaterial.EnableKeyword("_ALPHABLEND_ON");
    planeMaterial.DisableKeyword("_ALPHAPREMULTIPLY_ON");
    planeMaterial.renderQueue = 3000;
    
    planeMaterial.color = nothing;
  }

  public void callFadeOut(Action cb = null){
    //Debug.Log("fade out");

    if (coProcess != null) StopCoroutine(coProcess);
    coProcess = StartCoroutine(processFadeTo(planeMaterial.color, nothing, 1f, cb));
  }

  public void callFadeIn(Color overlay, Action cb = null){
    //Debug.Log("fade in");

    if (coProcess != null) StopCoroutine(coProcess);
    coProcess = StartCoroutine(processFadeTo(nothing, overlay, 0f, cb));
  }

  public void callFadeInOut(Color overlay, Action cbFadedIn = null, Action cbFadedOut = null){
    if (coProcess != null) StopCoroutine(coProcess);
    coProcess = StartCoroutine(processFadeTo(nothing, overlay, 0f,
      delegate() {
        if (coProcess != null) StopCoroutine(coProcess);
        coProcess = StartCoroutine(processFadeTo(planeMaterial.color, nothing, 1f, cbFadedOut));
      })
    );
  }
  
  IEnumerator processFadeTo(Color origin, Color target, float originAlpha = 1f, Action cb = null){
    startColor.r = origin.r;
    startColor.g = origin.g;
    startColor.b = origin.b;
    startColor.a = originAlpha;

    planeMaterial.color = startColor;

    cam.enabled = true;

    progress = 0f;
    
    endColor = target;

    while (planeMaterial.color != endColor)
    {
      progress += GameTime.deltaTime * fadeSpeed;
      planeMaterial.color = Color.Lerp(startColor, endColor, progress);
      yield return null;
    }

    cam.backgroundColor = endColor;

    if (cb != null) cb();
  }



  static public T createCarrier<T>(string nm) where T : MonoBehaviour
  {
    GameObject obj = GameObject.Find(nm);
    T tmp = null;
    if (obj != null)
    {
      tmp = obj.GetComponent<T>();
    }

    if (tmp != null) return tmp;

    if (obj == null)
    {
      obj = new GameObject(nm, typeof(T));
      tmp = obj.GetComponent<T>();
    }
    else tmp = obj.AddComponent<T>();

    return tmp;
  }

}