Fix slider tail volume not saving

osu.Game.Tests/Beatmaps/Formats/LegacyBeatmapDecoderTest.cs

@@ -528,8 +528,17 @@ public void TestDecodeControlPointCustomSampleBank()
                 Assert.AreEqual("Gameplay/normal-hitnormal2", getTestableSampleInfo(hitObjects[2]).LookupNames.First());
                 Assert.AreEqual("Gameplay/normal-hitnormal", getTestableSampleInfo(hitObjects[3]).LookupNames.First());
 
-                // The control point at the end time of the slider should be applied
-                Assert.AreEqual("Gameplay/soft-hitnormal8", getTestableSampleInfo(hitObjects[4]).LookupNames.First());
+                // The fourth object is a slider.
+                // `Samples` of a slider are presumed to control the volume of sounds that last the entire duration of the slider
+                // (such as ticks, slider slide sounds, etc.)
+                // Thus, the point of query of control points used for `Samples` is just beyond the start time of the slider.
+                Assert.AreEqual("Gameplay/soft-hitnormal11", getTestableSampleInfo(hitObjects[4]).LookupNames.First());
+
+                // That said, the `NodeSamples` of the slider are responsible for the sounds of the slider's head / tail / repeats / large ticks etc.
+                // Therefore, they should be read at the time instant correspondent to the given node.
+                // This means that the tail should use bank 8 rather than 11.
+                Assert.AreEqual("Gameplay/soft-hitnormal11", ((ConvertSlider)hitObjects[4]).NodeSamples[0][0].LookupNames.First());
+                Assert.AreEqual("Gameplay/soft-hitnormal8", ((ConvertSlider)hitObjects[4]).NodeSamples[1][0].LookupNames.First());
             }
 
             static HitSampleInfo getTestableSampleInfo(HitObject hitObject) => hitObject.Samples[0];

osu.Game.Tests/Resources/per-slider-node-sample-settings.osu

@@ -0,0 +1,22 @@
+osu file format v128
+
+[General]
+SampleSet: Normal
+
+[TimingPoints]
+15,1000,4,1,0,100,1,0
+2271,-100,4,1,0,5,0,0
+6021,-100,4,1,0,100,0,0
+8515,-100,4,1,0,5,0,0
+12765,-100,4,1,0,100,0,0
+14764,-100,4,1,0,5,0,0
+14770,-100,4,1,0,50,0,0
+17264,-100,4,1,0,5,0,0
+17270,-100,4,1,0,50,0,0
+22264,-100,4,1,0,100,0,0
+
+[HitObjects]
+113,54,2265,6,0,L|422:55,1,300,0|0,1:0|1:0,1:0:0:0:
+82,206,6015,2,0,L|457:204,1,350,0|0,2:0|2:0,2:0:0:0:
+75,310,10265,2,0,L|435:312,1,350,0|0,3:0|3:0,3:0:0:0:
+75,310,14764,2,0,L|435:312,3,350,0|0|0|0,3:0|3:0|3:0|3:0,3:0:0:0:

osu.Game/Beatmaps/Formats/LegacyBeatmapDecoder.cs

@@ -33,7 +33,7 @@ public class LegacyBeatmapDecoder : LegacyDecoder<Beatmap>
         /// <remarks>
         /// Compare: https://github.com/peppy/osu-stable-reference/blob/master/osu!/GameplayElements/HitObjects/HitObject.cs#L319
         /// </remarks>
-        private const double control_point_leniency = 5;
+        public const double CONTROL_POINT_LENIENCY = 5;
 
         internal static RulesetStore? RulesetStore;
 
@@ -160,20 +160,24 @@ private void applyDefaults(HitObject hitObject)
 
         private void applySamples(HitObject hitObject)
         {
-            SampleControlPoint sampleControlPoint = (beatmap.ControlPointInfo as LegacyControlPointInfo)?.SamplePointAt(hitObject.GetEndTime() + control_point_leniency) ?? SampleControlPoint.DEFAULT;
-
-            hitObject.Samples = hitObject.Samples.Select(o => sampleControlPoint.ApplyTo(o)).ToList();
-
             if (hitObject is IHasRepeats hasRepeats)
             {
+                SampleControlPoint sampleControlPoint = (beatmap.ControlPointInfo as LegacyControlPointInfo)?.SamplePointAt(hitObject.StartTime + CONTROL_POINT_LENIENCY + 1) ?? SampleControlPoint.DEFAULT;
+                hitObject.Samples = hitObject.Samples.Select(o => sampleControlPoint.ApplyTo(o)).ToList();
+
                 for (int i = 0; i < hasRepeats.NodeSamples.Count; i++)
                 {
-                    double time = hitObject.StartTime + i * hasRepeats.Duration / hasRepeats.SpanCount() + control_point_leniency;
+                    double time = hitObject.StartTime + i * hasRepeats.Duration / hasRepeats.SpanCount() + CONTROL_POINT_LENIENCY;
                     var nodeSamplePoint = (beatmap.ControlPointInfo as LegacyControlPointInfo)?.SamplePointAt(time) ?? SampleControlPoint.DEFAULT;
 
                     hasRepeats.NodeSamples[i] = hasRepeats.NodeSamples[i].Select(o => nodeSamplePoint.ApplyTo(o)).ToList();
                 }
             }
+            else
+            {
+                SampleControlPoint sampleControlPoint = (beatmap.ControlPointInfo as LegacyControlPointInfo)?.SamplePointAt(hitObject.GetEndTime() + CONTROL_POINT_LENIENCY) ?? SampleControlPoint.DEFAULT;
+                hitObject.Samples = hitObject.Samples.Select(o => sampleControlPoint.ApplyTo(o)).ToList();
+            }
         }
 
         /// <summary>

osu.Game/Beatmaps/Formats/LegacyBeatmapEncoder.cs

@@ -282,19 +282,39 @@ IEnumerable<SampleControlPoint> collectSampleControlPoints(IEnumerable<HitObject
             {
                 foreach (var hitObject in hitObjects)
                 {
-                    if (hitObject.Samples.Count > 0)
+                    if (hitObject is IHasRepeats hasNodeSamples)
                     {
-                        int volume = hitObject.Samples.Max(o => o.Volume);
-                        int customIndex = hitObject.Samples.Any(o => o is ConvertHitObjectParser.LegacyHitSampleInfo)
-                            ? hitObject.Samples.OfType<ConvertHitObjectParser.LegacyHitSampleInfo>().Max(o => o.CustomSampleBank)
-                            : -1;
+                        double spanDuration = hasNodeSamples.Duration / hasNodeSamples.SpanCount();
 
-                        yield return new LegacyBeatmapDecoder.LegacySampleControlPoint { Time = hitObject.GetEndTime(), SampleVolume = volume, CustomSampleBank = customIndex };
+                        for (int i = 0; i < hasNodeSamples.NodeSamples.Count; ++i)
+                        {
+                            double nodeTime = hitObject.StartTime + i * spanDuration;
+
+                            if (hasNodeSamples.NodeSamples[i].Count > 0)
+                                yield return createSampleControlPointFor(nodeTime, hasNodeSamples.NodeSamples[i]);
+
+                            if (spanDuration > LegacyBeatmapDecoder.CONTROL_POINT_LENIENCY + 1 && hitObject.Samples.Count > 0 && i < hasNodeSamples.NodeSamples.Count - 1)
+                                yield return createSampleControlPointFor(nodeTime + LegacyBeatmapDecoder.CONTROL_POINT_LENIENCY + 1, hitObject.Samples);
+                        }
+                    }
+                    else if (hitObject.Samples.Count > 0)
+                    {
+                        yield return createSampleControlPointFor(hitObject.GetEndTime(), hitObject.Samples);
                     }
 
                     foreach (var nested in collectSampleControlPoints(hitObject.NestedHitObjects))
                         yield return nested;
                 }
+
+                SampleControlPoint createSampleControlPointFor(double time, IList<HitSampleInfo> samples)
+                {
+                    int volume = samples.Max(o => o.Volume);
+                    int customIndex = samples.Any(o => o is ConvertHitObjectParser.LegacyHitSampleInfo)
+                        ? samples.OfType<ConvertHitObjectParser.LegacyHitSampleInfo>().Max(o => o.CustomSampleBank)
+                        : -1;
+
+                    return new LegacyBeatmapDecoder.LegacySampleControlPoint { Time = time, SampleVolume = volume, CustomSampleBank = customIndex };
+                }
             }
 
             void extractSampleControlPoints(IEnumerable<HitObject> hitObject)