plugin-library/Assets/04.AudioCore/RunTime/MusicPlayer.cs

using System.Collections;
using UnityEngine;

public class MusicPlayer
{
    private AudioSourcePool audioSourcePool;
    private AudioSource audioSource1;
    private AudioSource audioSource2;
    private AudioSource currentAudioSource;

    public MusicPlayer(AudioSourcePool audioSourcePool)
    {
        this.audioSourcePool = audioSourcePool;
    }

    /// <summary>
    /// 播放背景音乐
    /// </summary>
    /// <param name="clip">音频</param>
    /// <param name="volume">音量</param>
    /// <param name="fadeDuration">自然过渡时间</param>
    public void Play(AudioClip clip, float volume, float fadeDuration)
    {
        if(audioSource1 == null)
        {
            audioSource1 = audioSourcePool.GetAudioSource("Music");
            audioSource1.clip = clip;
            audioSource1.volume = volume;
            currentAudioSource = audioSource1;
            currentAudioSource.Play();
            CoroutineHelper.StartCoroutine(FadeMusic(audioSource1, fadeDuration, audioSource2));
        }
        else
        {
            if (audioSource2  == null)
            {
                audioSource2 = audioSourcePool.GetAudioSource("Music");
                audioSource2.clip = clip;
                audioSource2.volume = volume;
                currentAudioSource = audioSource2;
                currentAudioSource.Play();
                CoroutineHelper.StartCoroutine(FadeMusic(audioSource2, fadeDuration, audioSource1));
            }
            else
            {
                Debug.LogWarning("已同时存在两个背景乐在切换");
            }
        }
        
    }

    /// <summary>
    /// 关闭背景音乐
    /// </summary>
    /// <param name="fadeDuration">关闭时的自然过渡时间</param>
    public void Stop(float fadeDuration)
    {
        CoroutineHelper.StartCoroutine(FadeOutMusic(currentAudioSource, fadeDuration));
    }

    /// <summary>
    /// 切换音频
    /// </summary>
    /// <param name="source1">播放的音频</param>
    /// <param name="fadeDuration">变化时间</param>
    /// <param name="source2">停止的音频</param>
    /// <returns></returns>
    private IEnumerator FadeMusic(AudioSource source1, float fadeDuration, AudioSource source2 = null)
    {
        yield return FadeInMusic(source1, fadeDuration);

        if(source2 != null)
        {
            yield return FadeOutMusic(source2, fadeDuration);
        }
        
    }

    /// <summary>
    /// 关闭音频的协程
    /// </summary>
    /// <param name="source"></param>
    /// <param name="fadeDuration"></param>
    /// <returns></returns>
    private IEnumerator FadeOutMusic(AudioSource source, float fadeDuration)
    {
        float startVolume = source.volume;

        while (source.volume > 0)
        {
            source.volume -= startVolume * Time.deltaTime / fadeDuration;
            yield return null;
        }

        source.Stop();
        audioSourcePool.ReturnAudioSource("Music", source.gameObject);

        if(currentAudioSource == audioSource1)
        {
            audioSource2 = null;
        }
        else if(currentAudioSource == audioSource2)
        {
            audioSource1 = null;
        }
    }

    /// <summary>
    /// 开启音频的协程
    /// </summary>
    /// <param name="source"></param>
    /// <param name="fadeDuration"></param>
    /// <returns></returns>
    private IEnumerator FadeInMusic(AudioSource source, float fadeDuration)
    {
        float targetVolume = source.volume;
        source.volume = 0;

        while (source.volume < targetVolume)
        {
            source.volume += targetVolume * Time.deltaTime / fadeDuration;
            yield return null;
        }
    }
}