ヴァンサバ風ゲームの作り方#9｜HPとゲームオーバーを作ろう

    [SerializeField] private int touchDamage = 10;  // 触れたときに与えるダメージ

    // プレイヤー側から読む
    public int TouchDamage => touchDamage;

using System;
using UnityEngine;

// スライムちゃんのHP。敵に触れられると減り、0になったら終わり
public class PlayerHealth : MonoBehaviour
{
    [SerializeField] private int maxHp = 100;
    [SerializeField] private float invincibleSeconds = 0.5f; // 続けて減らない時間
    [SerializeField] private float blinkInterval = 0.08f;    // 点滅の速さ
    [SerializeField] private SpriteRenderer spriteRenderer;

    public int Hp { get; private set; }
    public int MaxHp => maxHp;

    // ダメージを受けたこと・やられたことを、ほかのスクリプトに知らせる
    public event Action Damaged;
    public event Action Died;

    private float invincibleTimer;

    private void Awake()
    {
        Hp = maxHp;
    }

    private void Update()
    {
        if (invincibleTimer <= 0f)
        {
            return;
        }

        invincibleTimer -= Time.deltaTime;

        // 無敵の間だけ、一定の間隔で見えたり消えたりさせる
        bool visible = invincibleTimer <= 0f || (int)(invincibleTimer / blinkInterval) % 2 == 0;
        spriteRenderer.enabled = visible;
    }

    private void OnTriggerStay2D(Collider2D other)
    {
        if (Hp <= 0 || invincibleTimer > 0f)
        {
            return;
        }
        if (!other.TryGetComponent(out Enemy enemy))
        {
            return;
        }

        Hp = Mathf.Max(0, Hp - enemy.TouchDamage);
        invincibleTimer = invincibleSeconds;
        Damaged?.Invoke();

        if (Hp <= 0)
        {
            spriteRenderer.enabled = true;
            Died?.Invoke();
        }
    }
}

    [SerializeField] private PlayerHealth playerHealth;
    [SerializeField] private Image hpBarFill;
    [SerializeField] private Image damageFlash;
    [SerializeField] private float flashAlpha = 0.35f;   // 光る強さ
    [SerializeField] private float flashSeconds = 0.3f;  // 消えるまでの秒数

        playerHealth.Damaged += ShowFlash;   // OnEnable
        playerHealth.Damaged -= ShowFlash;   // OnDisable

        hpBarFill.fillAmount = (float)playerHealth.Hp / playerHealth.MaxHp;

    private void ShowFlash()
    {
        StopCoroutine(nameof(FlashRoutine));
        StartCoroutine(nameof(FlashRoutine));
    }

    private IEnumerator FlashRoutine()
    {
        float timer = flashSeconds;
        while (timer > 0f)
        {
            timer -= Time.unscaledDeltaTime;
            float alpha = flashAlpha * (timer / flashSeconds);
            damageFlash.color = new Color(1f, 0f, 0f, alpha);
            yield return null;
        }
        damageFlash.color = new Color(1f, 0f, 0f, 0f);
    }

        StopCoroutine(nameof(PopLabel));
        StartCoroutine(nameof(PopLabel));

using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

// HPが0になったらゲームを止めて、パネルを出す
public class GameOverView : MonoBehaviour
{
    [SerializeField] private PlayerHealth playerHealth;
    [SerializeField] private GameObject panel;
    [SerializeField] private Button retryButton;

    private void OnEnable()
    {
        playerHealth.Died += Show;
        retryButton.onClick.AddListener(Retry);
    }

    private void OnDisable()
    {
        playerHealth.Died -= Show;
        retryButton.onClick.RemoveListener(Retry);
    }

    private void Show()
    {
        panel.SetActive(true);
        Time.timeScale = 0f;
    }

    private void Retry()
    {
        // 止めたまま読み込み直すと、次のゲームも止まったままになる
        Time.timeScale = 1f;
        SceneManager.LoadScene(SceneManager.GetActiveScene().name);
    }
}