Improve SFX playback behaviour of rapid kiai/star fountain activations

osu.Game/Screens/Menu/KiaiMenuFountains.cs

@@ -6,9 +6,7 @@ using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Platform;
 using osu.Framework.Utils;
-using osu.Game.Audio;
 using osu.Game.Graphics.Containers;
-using osu.Game.Skinning;
 
 namespace osu.Game.Screens.Menu
 {
@@ -20,7 +18,7 @@ namespace osu.Game.Screens.Menu
         [Resolved]
         private GameHost host { get; set; } = null!;
 
-        private SkinnableSound? sample;
+        private StarFountainSfx sfx = null!;
 
         [BackgroundDependencyLoader]
         private void load()
@@ -41,7 +39,7 @@ namespace osu.Game.Screens.Menu
                     Origin = Anchor.BottomRight,
                     X = -250,
                 },
-                sample = new SkinnableSound(new SampleInfo("Gameplay/fountain-shoot"))
+                sfx = new StarFountainSfx()
             };
         }
 
@@ -83,9 +81,9 @@ namespace osu.Game.Screens.Menu
                     break;
             }
 
-            // Don't play SFX when game is in background as it can be a bit noisy.
+            // Don't play SFX when game is in background, as it can be a bit noisy.
             if (host.IsActive.Value)
-                sample?.Play();
+                sfx.Trigger();
         }
     }
 }

osu.Game/Screens/Menu/StarFountainSfx.cs

@@ -0,0 +1,74 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Threading;
+using osu.Game.Audio;
+using osu.Game.Skinning;
+
+namespace osu.Game.Screens.Menu
+{
+    public partial class StarFountainSfx : Container
+    {
+        private const int shoot_retrigger_delay = 500;
+        private const int loop_fade_duration = 500;
+
+        private double? lastPlayback;
+
+        private SkinnableSound? shootSample;
+        private PausableSkinnableSound? loopSample;
+
+        private ScheduledDelegate? loopFadeDelegate;
+        private ScheduledDelegate? loopStopDelegate;
+
+        public void Trigger()
+        {
+            loopFadeDelegate?.Cancel();
+            loopStopDelegate?.Cancel();
+
+            // Only play 'shootSample' if enough time has passed since last `Trigger()` call.
+            if (lastPlayback == null || Time.Current - lastPlayback > shoot_retrigger_delay)
+            {
+                loopSample?.Stop();
+                shootSample?.Play();
+                lastPlayback = Time.Current;
+
+                return;
+            }
+
+            if (loopSample == null) return;
+
+            // Only call `Play()` if `loopSample` is not already playing, to prevent restarting the sample each time.
+            if (!loopSample.RequestedPlaying)
+            {
+                loopSample.Volume.Value = 1f;
+                loopSample.Play();
+            }
+
+            // Schedule a volume fadeout, followed by a `Stop()`.
+            loopFadeDelegate = Scheduler.AddDelayed(() =>
+            {
+                this.TransformBindableTo(loopSample.Volume, 0, loop_fade_duration);
+
+                loopStopDelegate = Scheduler.AddDelayed(() =>
+                {
+                    loopSample?.Stop();
+                }, loop_fade_duration);
+            }, shoot_retrigger_delay);
+
+            lastPlayback = Time.Current;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            Children = new Drawable[]
+            {
+                shootSample = new SkinnableSound(new SampleInfo("Gameplay/fountain-shoot")),
+                loopSample = new PausableSkinnableSound(new SampleInfo("Gameplay/fountain-loop")) { Looping = true },
+            };
+        }
+    }
+}

osu.Game/Screens/Play/KiaiGameplayFountains.cs

@@ -6,11 +6,9 @@ using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Utils;
-using osu.Game.Audio;
 using osu.Game.Configuration;
 using osu.Game.Graphics.Containers;
 using osu.Game.Screens.Menu;
-using osu.Game.Skinning;
 
 namespace osu.Game.Screens.Play
 {
@@ -21,7 +19,7 @@ namespace osu.Game.Screens.Play
 
         private Bindable<bool> kiaiStarFountains = null!;
 
-        private SkinnableSound? sample;
+        private StarFountainSfx sfx = null!;
 
         [BackgroundDependencyLoader]
         private void load(OsuConfigManager config)
@@ -44,7 +42,7 @@ namespace osu.Game.Screens.Play
                     Origin = Anchor.BottomRight,
                     X = -75,
                 },
-                sample = new SkinnableSound(new SampleInfo("Gameplay/fountain-shoot"))
+                sfx = new StarFountainSfx(),
             };
         }
 
@@ -72,7 +70,7 @@ namespace osu.Game.Screens.Play
             leftFountain.Shoot(1);
             rightFountain.Shoot(-1);
 
-            sample?.Play();
+            sfx.Trigger();
         }
 
         public partial class GameplayStarFountain : StarFountain