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

public class FadeToBlack : MonoBehaviour
{
    public float fadeDuration = 1.5f; // 渐变时间
    private Image blackImage;

    void Start()
    {
        blackImage = GetComponent<Image>();
      
    }

    // 外部调用：渐变变黑
    public void StartFade()
    {
        StartCoroutine(FadeToBlackCoroutine());
    }

    // 外部调用：直接变黑
    public void InstantBlack()
    {
        blackImage.color = new Color(0, 0, 0, 1f); // 设置为全黑
    }

    // 协程：控制渐变过程
    private IEnumerator FadeToBlackCoroutine()
    {
        float elapsedTime = 0f;

        while (elapsedTime < fadeDuration)
        {
            elapsedTime += Time.deltaTime;
            float alpha = Mathf.Clamp01(elapsedTime / fadeDuration); // 计算透明度
            blackImage.color = new Color(0, 0, 0, alpha);
            yield return null; // 等待下一帧
        }

        // 确保最终完全变黑
        blackImage.color = new Color(0, 0, 0, 0.6f);
    }
}