【Unity】指向性スピーカーの実装例

AudioSource の向きで音量や聞こえる距離が変わるコンポーネントを作りました。
AudioSource が AudioListener に向くほど、大きく遠くまで聞こえるようになります。
声やスピーカーにご利用ください。

DirectionalAudioSource.cs

using UnityEngine;

public class DirectionalAudioSource : MonoBehaviour
{
    [SerializeField] private AudioSource audioSource;
    [SerializeField] private Transform audioSourceTransform;
    [SerializeField] private Transform listenerTransform;
    [SerializeField] private AnimationCurve curve = new AnimationCurve(new Keyframe[2] { new Keyframe(0f, 0f), new Keyframe(1f, 1f) });
    [SerializeField, Range(0f, 1f)] private float minVolume = 0.25f;
    [SerializeField, Range(0f, 1f)] private float maxVolume = 1f;

    private float maxDistance;


    private void Start()
    {
        maxDistance = audioSource.maxDistance;
    }
    void Update()
    {
        if (listenerTransform == null && FindAudioListener()) return;
        UpdateVolume();
    }

    public void UpdateVolume()
    {
        var volume = Mathf.LerpUnclamped(minVolume, maxVolume, curve.Evaluate(GetVolume()));
        audioSource.maxDistance = volume * maxDistance;
        audioSource.volume = volume;
    }
    private float GetVolume() => Vector3.Dot(audioSourceTransform.forward, (listenerTransform.position - audioSourceTransform.position).normalized) * 0.5f + 0.5f;
    
    public void SetAudioListener(AudioListener audioListener) => listenerTransform = audioListener.transform;
    public bool FindAudioListener()
    {
        var listener = FindObjectOfType<AudioListener>();
        if (listener == null) return false;
        listenerTransform = listener.transform;
        return true;
    }
    
#if UNITY_EDITOR
    private void OnValidate()
    {
        if (audioSource == null)
        {
            audioSource = GetComponent<AudioSource>();
            if (audioSource != null) audioSourceTransform = audioSource.transform;
        }
    }
#endif
}