Ambient loops (#323)

* ambient loop systems

* audio content

* Update ContentAudioSystem.CP14AmbientLoop.cs

* Update attributions.yml

* limit frequency

* Update CP14AmbientLoopPrototype.cs

* Create IsDaylight.cs

* fix problem

Content.Client/Audio/ContentAudioSystem.CP14AmbientLoop.cs

@@ -0,0 +1,122 @@
+using System.Linq;
+using Content.Client.Gameplay;
+using Content.Shared.Audio;
+using Content.Shared.CCVar;
+using Robust.Shared.Audio;
+using Robust.Shared.Audio.Systems;
+using Robust.Shared.Player;
+
+namespace Content.Client.Audio;
+
+public sealed partial class ContentAudioSystem
+{
+    private const float AmbientLoopFadeInTime = 1f;
+    private const float AmbientLoopFadeOutTime = 4f;
+
+    private Dictionary<CP14AmbientLoopPrototype, EntityUid> _loopStreams = new();
+
+    private TimeSpan _nextUpdateTime = TimeSpan.Zero;
+    private readonly TimeSpan _updateFrequency = TimeSpan.FromSeconds(1f);
+
+    private void CP14InitializeAmbientLoops()
+    {
+        Subs.CVar(_configManager, CCVars.AmbientMusicVolume, AmbienceCVarChangedAmbientMusic, true);
+    }
+
+    private void AmbienceCVarChangedAmbientMusic(float obj)
+    {
+        _volumeSlider = SharedAudioSystem.GainToVolume(obj);
+
+        foreach (var loop in _loopStreams)
+        {
+            _audio.SetVolume(loop.Value, loop.Key.Sound.Params.Volume + _volumeSlider);
+        }
+    }
+
+   private void OnRoundEndMessageAmbientLoop()
+   {
+       foreach (var loop in _loopStreams)
+       {
+           StopAmbientLoop(loop.Key);
+       }
+   }
+
+   private void CP14UpdateAmbientLoops()
+   {
+       if (_timing.CurTime <= _nextUpdateTime)
+           return;
+
+       _nextUpdateTime = _timing.CurTime + _updateFrequency;
+
+
+       if (_state.CurrentState is not GameplayState)
+           return;
+
+       var requiredLoops = GetAmbientLoops();
+
+       foreach (var loop in _loopStreams)
+       {
+           if (!requiredLoops.Contains(loop.Key))  //If ambient is playing and it shouldn't, stop it.
+               StopAmbientLoop(loop.Key);
+       }
+
+       foreach (var loop in requiredLoops)
+       {
+           if (!_loopStreams.ContainsKey(loop)) //If it's not playing, but should, run it
+               StartAmbientLoop(loop);
+       }
+   }
+
+   private void StartAmbientLoop(CP14AmbientLoopPrototype proto)
+   {
+       if (_loopStreams.ContainsKey(proto))
+           return;
+
+       var newLoop = _audio.PlayGlobal(
+           proto.Sound,
+           Filter.Local(),
+           false,
+           AudioParams.Default
+               .WithLoop(true)
+               .WithVolume(proto.Sound.Params.Volume + _volumeSlider)
+               .WithPlayOffset(_random.NextFloat(0f, 100f)));
+       _loopStreams.Add(proto, newLoop.Value.Entity);
+
+       FadeIn(newLoop.Value.Entity, newLoop.Value.Component, AmbientLoopFadeInTime);
+   }
+
+   private void StopAmbientLoop(CP14AmbientLoopPrototype proto)
+   {
+       if (!_loopStreams.TryGetValue(proto, out var audioEntity))
+           return;
+
+       FadeOut(audioEntity, duration: AmbientLoopFadeOutTime);
+       _loopStreams.Remove(proto);
+   }
+
+   /// <summary>
+   /// Checks the player's environment, and returns a list of all ambients that should currently be playing around the player
+   /// </summary>
+   /// <returns></returns>
+   private List<CP14AmbientLoopPrototype> GetAmbientLoops()
+   {
+       List<CP14AmbientLoopPrototype> list = new();
+
+       var player = _player.LocalEntity;
+
+       if (player == null)
+           return list;
+
+       var ambientLoops = _proto.EnumeratePrototypes<CP14AmbientLoopPrototype>().ToList();
+
+       foreach (var loop in ambientLoops)
+       {
+           if (_rules.IsTrue(player.Value, _proto.Index(loop.Rules)))
+           {
+               list.Add(loop);
+           }
+       }
+
+       return list;
+   }
+}