Why the fading is not continue from the current point when changing the fading direction ?

Unity Engine
,
1 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Fader : MonoBehaviour
{
    public CanvasGroup canvasGroup;
    public GameObject objectToScale;
    public float duration = 1f;
    public Vector3 minSize;
    public Vector3 maxSize;
    public bool scaleUp = false;
    public Coroutine scaleCoroutine;
    public bool isAutomatic = false;

    private bool automatic = true;

    private void Start()
    {
        objectToScale.transform.localScale = minSize;
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.G))
        {
            Fade();
        }

        if (isAutomatic && automatic)
        {
            Fade();

            automatic = false;
        }
    }

    private IEnumerator ScaleOverTime(GameObject targetObj,
        Vector2 lerpto/*Vector3 toScale*/, float duration)
    {
        float counter = 0;
        Vector3 startScaleSize = targetObj.transform.localScale;

        while (counter < duration)
        {
            counter += Time.deltaTime;
            //targetObj.transform.localScale = Vector3.Lerp(startScaleSize, toScale, counter / duration);
            canvasGroup.alpha = Mathf.Lerp(lerpto.x, lerpto.y, counter / duration);

            yield return null;
        }

        yield return null;

        automatic = true;
    }

    private void Fade()
    {
        scaleUp = !scaleUp;

        if (scaleCoroutine != null)
        {
            StopCoroutine(scaleCoroutine);
        }

        if (scaleUp)
        {
            scaleCoroutine = StartCoroutine(ScaleOverTime(objectToScale, maxSize, duration));
        }

        else
        {
            scaleCoroutine = StartCoroutine(ScaleOverTime(objectToScale, minSize, duration));
        }
    }
}

it was working fine when i used Vector3.Lerp to scale object up/down :

targetObj.transform.localScale = Vector3.Lerp(startScaleSize, toScale, counter / duration);

I pressed the G key and while it was scaling up or down i pressed G again in the middle and it was changing the scaling direction from the current point.

but once i changed it to Mathf.Lerp :

canvasGroup.alpha = Mathf.Lerp(lerpto.x, lerpto.y, counter / duration);

to change canvasgroup alpha from 0 to 1 when i press the G key and it’s fading up or down and then pressing G key in the middle it’s starting from the changed direction and not continue to the new changed direction.

how can i make that it will also continue when changing the direction/s using the Mathf.Lerp ?

2

What are your Inspector values?

3

WOW! A new record… 79 lines for a fader.

It really should only be 2 lines of variables and one line of code.

Much less chance of bugs, plus this one goes back and forth anytime you like.

Fading, simple and easy: