holopy3/Assets/Scripts/FadingColors.cs

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

public class FadingColors : MonoBehaviour
{
    [SerializeField] Color color1;
    [SerializeField] Color color2;
    [SerializeField] Color color3;
    [SerializeField] float interval;

    private Gradient gradient;
    private GradientColorKey[] colorKey;
    private GradientAlphaKey[] alphaKey;

    private float time;
    private bool timePlus;
    private MeshRenderer m;

    private Button button;
    private ColorBlock cb;
    private Image image;
    private Color col;


    void Start()
    {
        time = 0f;
        timePlus = true;

        gradient = new Gradient();

        // Populate the color keys at the relative time 0 and 1 (0 and 100%)
        colorKey = new GradientColorKey[3];
        colorKey[0].color = color1;
        colorKey[0].time = 0.0f;
        colorKey[1].color = color2;
        colorKey[1].time = 0.5f;
        colorKey[2].color = color3;
        colorKey[2].time = 1.0f;

        // Populate the alpha  keys at relative time 0 and 1  (0 and 100%)
        alphaKey = new GradientAlphaKey[3];
        alphaKey[0].alpha = 0.0f;
        alphaKey[0].time = 0.0f;
        alphaKey[1].alpha = 0.5f;
        alphaKey[1].time = 0.5f;
        alphaKey[2].alpha = 1.0f;
        alphaKey[2].time = 1.0f;

        gradient.SetKeys(colorKey, alphaKey);

        // What's the color at the relative time 0.25 (25 %) ?
        Debug.Log(gradient.Evaluate(0.25f));

        m = GetComponent<MeshRenderer>();
    }

    private void Update()
    {
        if (timePlus)
        {
            time += Time.deltaTime;

            if (time > interval)
            {
                timePlus = false;
            }
        }
        if (!timePlus)
        {
            time -= Time.deltaTime;

            if (time < 0)
            {
                timePlus = true;
            }
        }

        m.material.color = gradient.Evaluate(time / interval);
    }
}