environment management

Assets/Engine/Runtime/Environment/AmbienceAudio.cs

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+using System;
+using System.Collections;
+using NaughtyAttributes;
+using UnityEngine;
+
+namespace EscapeRoomEngine.Engine.Runtime.Environment
+{
+    [RequireComponent(typeof(AudioSource))]
+    public class AmbienceAudio : MonoBehaviour
+    {
+        public static AmbienceAudio Instance { get; private set; }
+        
+        public float fadeDuration = 0.5f;
+        public AmbienceClip initialAmbience;
+        [BoxGroup("Internal")] [SerializeField] private AudioSource[] sources;
+
+        private AudioSource CurrentSource => sources[currentSource];
+        private AudioSource OtherSource => sources[(currentSource + 1) % 2];
+        
+        private int currentSource;
+        private readonly Coroutine[] _activeFades = new Coroutine[2]; // the indices in these fades do not necessarily correspond to the sources
+
+        private void Awake()
+        {
+            Instance = this;
+            
+            if (sources.Length != 2)
+            {
+                throw new Exception("There must be two sources.");
+            }
+            if (CurrentSource == OtherSource)
+            {
+                throw new Exception("Current source must be different from other source.");
+            }
+
+            foreach (var source in sources)
+            {
+                source.loop = true;
+            }
+        }
+
+        public void StartAmbience()
+        {
+            CrossFadeTo(initialAmbience);
+        }
+
+        public void CrossFadeTo(AmbienceClip ambience)
+        {
+            // prepare fade source
+            var fadeSource = OtherSource;
+            fadeSource.clip = ambience.audio;
+            fadeSource.Play();
+
+            // stop any running fades
+            foreach (var fade in _activeFades)
+            {
+                if (fade != null)
+                {
+                    StopCoroutine(fade);
+                }
+            }
+            
+            // start new fades
+            _activeFades[0] = StartCoroutine(Fade(CurrentSource, CurrentSource.volume, 0));
+            _activeFades[1] = StartCoroutine(Fade(fadeSource, fadeSource.volume, ambience.volume));
+
+            // switch current source
+            currentSource = (currentSource + 1) % 2;
+        }
+
+        private IEnumerator Fade(AudioSource source, float from, float to)
+        {
+            var startTime = Time.time;
+
+            while (Math.Abs(source.volume - to) > 0.0001f)
+            {
+                source.volume = Mathf.Clamp01(Mathf.Lerp(
+                    from,
+                    to,
+                    (Time.time - startTime) / fadeDuration));
+                yield return null;
+            }
+        }
+    }
+}