fgm24/Assets/Scripts/UI/WaveUI.cs

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

public class WaveUI : MonoBehaviour
{
    [SerializeField] private EnemySpawner spawner;
    [SerializeField] private Slider slider;
    [SerializeField] private TMP_Text waveText;
    [SerializeField] private float waveTextDisplayTime = 3f;

    private void Start()
    {
        waveText.color = new Color(1, 1, 1, 0);
    }

    int prevWave = 0;
    private void Update()
    {
        float waveProgressTime = spawner.timer / spawner.WaveTime;
        slider.value = waveProgressTime;

        if (prevWave != spawner.Wave)
        {
            prevWave = spawner.Wave;
            StartCoroutine(ShowWave());
        }    
    }

    IEnumerator ShowWave()
    {
        waveText.text = $"Wave: {spawner.Wave}";



        Color color = new Color(1, 1, 1, 0);
        while (color.a < 1)
        {
            color.a += 0.05f;
            waveText.color = color;
            yield return new WaitForSecondsRealtime(0.05f);
        }

        yield return new WaitForSecondsRealtime(waveTextDisplayTime);

        color = new Color(1, 1, 1, 1);
        while (color.a >= 0)
        {
            color.a -= 0.05f;
            waveText.color = color;
            yield return new WaitForSecondsRealtime(0.05f);
        }
    }
}