Merge pull request #24966 from peppy/legacy-tick-test-coverage

Adjust slider ends to be more lenient during very fast sliders

osu.Game.Rulesets.Osu.Tests/Mods/TestSceneOsuModAutoplay.cs

@@ -51,8 +51,9 @@ namespace osu.Game.Rulesets.Osu.Tests.Mods
                 FinalRate = { Value = 1.3 }
             });
 
-        [Test]
+        [TestCase(6.25f)]
-        public void TestPerfectScoreOnShortSliderWithRepeat()
+        [TestCase(20)]
+        public void TestPerfectScoreOnShortSliderWithRepeat(float pathLength)
         {
             AddStep("set score to standardised", () => LocalConfig.SetValue(OsuSetting.ScoreDisplayMode, ScoringMode.Standardised));
 
@@ -70,7 +71,7 @@ namespace osu.Game.Rulesets.Osu.Tests.Mods
                             Path = new SliderPath(new[]
                             {
                                 new PathControlPoint(),
-                                new PathControlPoint(new Vector2(0, 6.25f))
+                                new PathControlPoint(new Vector2(0, pathLength))
                             }),
                             RepeatCount = 1,
                             SliderVelocityMultiplier = 10

osu.Game.Rulesets.Osu.Tests/OsuBeatmapConversionTest.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using NUnit.Framework;
 using osu.Framework.Utils;
 using osu.Game.Rulesets.Objects;
@@ -33,8 +34,21 @@ namespace osu.Game.Rulesets.Osu.Tests
             switch (hitObject)
             {
                 case Slider slider:
+                    var objects = new List<ConvertValue>();
+
                     foreach (var nested in slider.NestedHitObjects)
-                        yield return createConvertValue((OsuHitObject)nested);
+                        objects.Add(createConvertValue((OsuHitObject)nested, slider));
+
+                    // stable does slider tail leniency by offsetting the last tick 36ms back.
+                    // based on player feedback, we're doing this a little different in lazer,
+                    // and the lazer method does not require offsetting the last tick
+                    // (see `DrawableSliderTail.CheckForResult()`).
+                    // however, in conversion tests, just so the output matches, we're bringing
+                    // the 36ms offset back locally.
+                    // in particular, on some sliders, this may rearrange nested objects,
+                    // so we sort them again by start time to prevent test failures.
+                    foreach (var obj in objects.OrderBy(cv => cv.StartTime))
+                        yield return obj;
 
                     break;
 
@@ -44,14 +58,30 @@ namespace osu.Game.Rulesets.Osu.Tests
                     break;
             }
 
-            static ConvertValue createConvertValue(OsuHitObject obj) => new ConvertValue
+            static ConvertValue createConvertValue(OsuHitObject obj, OsuHitObject? parent = null)
             {
-                StartTime = obj.StartTime,
+                double startTime = obj.StartTime;
-                EndTime = obj.GetEndTime(),
+                double endTime = obj.GetEndTime();
+
+                // as stated in the inline comment above, this is locally bringing back
+                // the stable treatment of the "legacy last tick" just to make sure
+                // that the conversion output matches.
+                // compare: `SliderEventGenerator.Generate()`, and the calculation of `legacyLastTickTime`.
+                if (obj is SliderTailCircle && parent is Slider slider)
+                {
+                    startTime = Math.Max(startTime + SliderEventGenerator.TAIL_LENIENCY, slider.StartTime + slider.Duration / 2);
+                    endTime = Math.Max(endTime + SliderEventGenerator.TAIL_LENIENCY, slider.StartTime + slider.Duration / 2);
+                }
+
+                return new ConvertValue
+                {
+                    StartTime = startTime,
+                    EndTime = endTime,
                     X = obj.StackedPosition.X,
                     Y = obj.StackedPosition.Y
                 };
             }
+        }
 
         protected override Ruleset CreateRuleset() => new OsuRuleset();
     }

osu.Game.Rulesets.Osu.Tests/OsuDifficultyCalculatorTest.cs

@@ -17,16 +17,19 @@ namespace osu.Game.Rulesets.Osu.Tests
 
         [TestCase(6.7115569159190587d, 206, "diffcalc-test")]
         [TestCase(1.4391311903612753d, 45, "zero-length-sliders")]
+        [TestCase(0.42506480230838789d, 2, "very-fast-slider")]
         [TestCase(0.14102693012101306d, 1, "nan-slider")]
         public void Test(double expectedStarRating, int expectedMaxCombo, string name)
             => base.Test(expectedStarRating, expectedMaxCombo, name);
 
         [TestCase(8.9757300665532966d, 206, "diffcalc-test")]
+        [TestCase(0.55071082800473514d, 2, "very-fast-slider")]
         [TestCase(1.7437232654020756d, 45, "zero-length-sliders")]
         public void TestClockRateAdjusted(double expectedStarRating, int expectedMaxCombo, string name)
             => Test(expectedStarRating, expectedMaxCombo, name, new OsuModDoubleTime());
 
         [TestCase(6.7115569159190587d, 239, "diffcalc-test")]
+        [TestCase(0.42506480230838789d, 4, "very-fast-slider")]
         [TestCase(1.4391311903612753d, 54, "zero-length-sliders")]
         public void TestClassicMod(double expectedStarRating, int expectedMaxCombo, string name)
             => Test(expectedStarRating, expectedMaxCombo, name, new OsuModClassic());

osu.Game.Rulesets.Osu.Tests/TestSceneSliderInput.cs

@@ -1,13 +1,12 @@
 // 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.
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 using NUnit.Framework;
 using osu.Framework.Screens;
 using osu.Game.Beatmaps;
+using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Replays;
 using osu.Game.Rulesets.Judgements;
 using osu.Game.Rulesets.Objects;
@@ -33,7 +32,100 @@ namespace osu.Game.Rulesets.Osu.Tests
         private const double time_during_slide_4 = 3800;
         private const double time_slider_end = 4000;
 
-        private List<JudgementResult> judgementResults;
+        private ScoreAccessibleReplayPlayer currentPlayer = null!;
+
+        private const float slider_path_length = 25;
+
+        private readonly List<JudgementResult> judgementResults = new List<JudgementResult>();
+
+        // Making these too short causes breakage from frames not being processed fast enough.
+        // To keep things simple, these tests are crafted to always be >16ms length.
+        // If sliders shorter than this are ever used in gameplay it will probably break things and we can revisit.
+        [TestCase(30, 0)]
+        [TestCase(30, 1)]
+        [TestCase(40, 0)]
+        [TestCase(40, 1)]
+        [TestCase(50, 1)]
+        [TestCase(60, 1)]
+        [TestCase(70, 1)]
+        [TestCase(80, 1)]
+        [TestCase(80, 0)]
+        [TestCase(80, 10)]
+        [TestCase(90, 1)]
+        [Ignore("headless test doesn't run at high enough precision for this to always enter a tracking state in time.")]
+        public void TestVeryShortSlider(float sliderLength, int repeatCount)
+        {
+            Slider slider;
+
+            performTest(new List<ReplayFrame>
+            {
+                new OsuReplayFrame { Position = new Vector2(10, 0), Actions = { OsuAction.LeftButton, OsuAction.RightButton }, Time = time_slider_start - 10 },
+                new OsuReplayFrame { Position = new Vector2(10, 0), Actions = { OsuAction.LeftButton, OsuAction.RightButton }, Time = time_slider_start + 2000 },
+            }, slider = new Slider
+            {
+                StartTime = time_slider_start,
+                Position = new Vector2(0, 0),
+                SliderVelocityMultiplier = 10f,
+                RepeatCount = repeatCount,
+                Path = new SliderPath(PathType.Linear, new[]
+                {
+                    Vector2.Zero,
+                    new Vector2(sliderLength, 0),
+                }),
+            }, 240, 1);
+
+            assertAllMaxJudgements();
+
+            // Even if the last tick is hit early, the slider should always execute its final judgement at its endtime.
+            // If not, hitsounds will not play on time.
+            AddAssert("Judgement offset is zero", () => judgementResults.Last().TimeOffset == 0);
+            AddAssert("Slider judged at end time", () => judgementResults.Last().TimeAbsolute, () => Is.EqualTo(slider.EndTime));
+
+            AddAssert("Slider is last judgement", () => judgementResults[^1].HitObject, Is.TypeOf<Slider>);
+            AddAssert("Tail is second last judgement", () => judgementResults[^2].HitObject, Is.TypeOf<SliderTailCircle>);
+        }
+
+        [TestCase(300, false)]
+        [TestCase(200, true)]
+        [TestCase(150, true)]
+        [TestCase(120, true)]
+        [TestCase(60, true)]
+        [TestCase(10, true)]
+        [TestCase(0, true)]
+        [TestCase(-30, false)]
+        [Ignore("headless test doesn't run at high enough precision for this to always enter a tracking state in time.")]
+        public void TestTailLeniency(float finalPosition, bool hit)
+        {
+            Slider slider;
+
+            performTest(new List<ReplayFrame>
+            {
+                new OsuReplayFrame { Position = Vector2.Zero, Actions = { OsuAction.LeftButton, OsuAction.RightButton }, Time = time_slider_start },
+                new OsuReplayFrame { Position = new Vector2(finalPosition, slider_path_length * 3), Actions = { OsuAction.LeftButton, OsuAction.RightButton }, Time = time_slider_start + 20 },
+            }, slider = new Slider
+            {
+                StartTime = time_slider_start,
+                Position = new Vector2(0, 0),
+                SliderVelocityMultiplier = 10f,
+                Path = new SliderPath(PathType.Linear, new[]
+                {
+                    Vector2.Zero,
+                    new Vector2(slider_path_length * 10, 0),
+                    new Vector2(slider_path_length * 10, slider_path_length * 3),
+                    new Vector2(0, slider_path_length * 3),
+                }),
+            }, 240, 1);
+
+            if (hit)
+                assertAllMaxJudgements();
+            else
+                AddAssert("Tracking dropped", assertMidSliderJudgementFail);
+
+            // Even if the last tick is hit early, the slider should always execute its final judgement at its endtime.
+            // If not, hitsounds will not play on time.
+            AddAssert("Judgement offset is zero", () => judgementResults.Last().TimeOffset == 0);
+            AddAssert("Slider judged at end time", () => judgementResults.Last().TimeAbsolute, () => Is.EqualTo(slider.EndTime));
+        }
 
         [Test]
         public void TestPressBothKeysSimultaneouslyAndReleaseOne()
@@ -44,7 +136,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                 new OsuReplayFrame { Position = Vector2.Zero, Actions = { OsuAction.RightButton }, Time = time_during_slide_1 },
             });
 
-            AddAssert("Tracking retained", assertMaxJudge);
+            assertAllMaxJudgements();
         }
 
         /// <summary>
@@ -86,7 +178,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                 new OsuReplayFrame { Position = new Vector2(0, 0), Actions = { OsuAction.RightButton }, Time = time_during_slide_2 },
             });
 
-            AddAssert("Tracking retained", assertMaxJudge);
+            assertAllMaxJudgements();
         }
 
         /// <summary>
@@ -107,7 +199,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                 new OsuReplayFrame { Position = new Vector2(0, 0), Actions = { OsuAction.RightButton }, Time = time_during_slide_1 },
             });
 
-            AddAssert("Tracking retained", assertMaxJudge);
+            assertAllMaxJudgements();
         }
 
         /// <summary>
@@ -128,7 +220,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                 new OsuReplayFrame { Position = new Vector2(0, 0), Actions = { OsuAction.RightButton }, Time = time_during_slide_1 },
             });
 
-            AddAssert("Tracking retained", assertMaxJudge);
+            assertAllMaxJudgements();
         }
 
         /// <summary>
@@ -301,7 +393,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                 new OsuReplayFrame { Position = new Vector2(slider_path_length, OsuHitObject.OBJECT_RADIUS * 1.199f), Actions = { OsuAction.LeftButton }, Time = time_slider_end },
             });
 
-            AddAssert("Tracking kept", assertMaxJudge);
+            assertAllMaxJudgements();
         }
 
         /// <summary>
@@ -325,7 +417,13 @@ namespace osu.Game.Rulesets.Osu.Tests
             AddAssert("Tracking dropped", assertMidSliderJudgementFail);
         }
 
-        private bool assertMaxJudge() => judgementResults.Any() && judgementResults.All(t => t.Type == t.Judgement.MaxResult);
+        private void assertAllMaxJudgements()
+        {
+            AddAssert("All judgements max", () =>
+            {
+                return judgementResults.Select(j => (j.HitObject, j.Type));
+            }, () => Is.EqualTo(judgementResults.Select(j => (j.HitObject, j.Judgement.MaxResult))));
+        }
 
         private bool assertHeadMissTailTracked() => judgementResults[^2].Type == HitResult.SmallTickHit && !judgementResults.First().IsHit;
 
@@ -333,19 +431,9 @@ namespace osu.Game.Rulesets.Osu.Tests
 
         private bool assertMidSliderJudgementFail() => judgementResults[^2].Type == HitResult.SmallTickMiss;
 
-        private ScoreAccessibleReplayPlayer currentPlayer;
+        private void performTest(List<ReplayFrame> frames, Slider? slider = null, double? bpm = null, int? tickRate = null)
-
-        private const float slider_path_length = 25;
-
-        private void performTest(List<ReplayFrame> frames)
         {
-            AddStep("load player", () =>
+            slider ??= new Slider
-            {
-                Beatmap.Value = CreateWorkingBeatmap(new Beatmap<OsuHitObject>
-                {
-                    HitObjects =
-                    {
-                        new Slider
             {
                 StartTime = time_slider_start,
                 Position = new Vector2(0, 0),
@@ -355,13 +443,24 @@ namespace osu.Game.Rulesets.Osu.Tests
                     Vector2.Zero,
                     new Vector2(slider_path_length, 0),
                 }, slider_path_length),
-                        }
+            };
-                    },
+
+            AddStep("load player", () =>
+            {
+                var cpi = new ControlPointInfo();
+
+                if (bpm != null)
+                    cpi.Add(0, new TimingControlPoint { BeatLength = 60000 / bpm.Value });
+
+                Beatmap.Value = CreateWorkingBeatmap(new Beatmap<OsuHitObject>
+                {
+                    HitObjects = { slider },
                     BeatmapInfo =
                     {
-                        Difficulty = new BeatmapDifficulty { SliderTickRate = 3 },
+                        Difficulty = new BeatmapDifficulty { SliderTickRate = tickRate ?? 3 },
-                        Ruleset = new OsuRuleset().RulesetInfo
+                        Ruleset = new OsuRuleset().RulesetInfo,
                     },
+                    ControlPointInfo = cpi,
                 });
 
                 var p = new ScoreAccessibleReplayPlayer(new Score { Replay = new Replay { Frames = frames } });
@@ -375,7 +474,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                 };
 
                 LoadScreen(currentPlayer = p);
-                judgementResults = new List<JudgementResult>();
+                judgementResults.Clear();
             });
 
             AddUntilStep("Beatmap at 0", () => Beatmap.Value.Track.CurrentTime == 0);

osu.Game.Rulesets.Osu/Difficulty/Evaluators/AimEvaluator.cs

@@ -24,7 +24,7 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Evaluators
         /// <item><description>and slider difficulty.</description></item>
         /// </list>
         /// </summary>
-        public static double EvaluateDifficultyOf(DifficultyHitObject current, bool withSliders)
+        public static double EvaluateDifficultyOf(DifficultyHitObject current, bool withSliderTravelDistance)
         {
             if (current.BaseObject is Spinner || current.Index <= 1 || current.Previous(0).BaseObject is Spinner)
                 return 0;
@@ -37,7 +37,7 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Evaluators
             double currVelocity = osuCurrObj.LazyJumpDistance / osuCurrObj.StrainTime;
 
             // But if the last object is a slider, then we extend the travel velocity through the slider into the current object.
-            if (osuLastObj.BaseObject is Slider && withSliders)
+            if (osuLastObj.BaseObject is Slider && withSliderTravelDistance)
             {
                 double travelVelocity = osuLastObj.TravelDistance / osuLastObj.TravelTime; // calculate the slider velocity from slider head to slider end.
                 double movementVelocity = osuCurrObj.MinimumJumpDistance / osuCurrObj.MinimumJumpTime; // calculate the movement velocity from slider end to current object
@@ -48,7 +48,7 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Evaluators
             // As above, do the same for the previous hitobject.
             double prevVelocity = osuLastObj.LazyJumpDistance / osuLastObj.StrainTime;
 
-            if (osuLastLastObj.BaseObject is Slider && withSliders)
+            if (osuLastLastObj.BaseObject is Slider && withSliderTravelDistance)
             {
                 double travelVelocity = osuLastLastObj.TravelDistance / osuLastLastObj.TravelTime;
                 double movementVelocity = osuLastObj.MinimumJumpDistance / osuLastObj.MinimumJumpTime;
@@ -122,7 +122,7 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Evaluators
             aimStrain += Math.Max(acuteAngleBonus * acute_angle_multiplier, wideAngleBonus * wide_angle_multiplier + velocityChangeBonus * velocity_change_multiplier);
 
             // Add in additional slider velocity bonus.
-            if (withSliders)
+            if (withSliderTravelDistance)
                 aimStrain += sliderBonus * slider_multiplier;
 
             return aimStrain;

osu.Game.Rulesets.Osu/Difficulty/Preprocessing/OsuDifficultyHitObject.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using osu.Game.Rulesets.Difficulty.Preprocessing;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Osu.Mods;
@@ -214,7 +215,45 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Preprocessing
             if (slider.LazyEndPosition != null)
                 return;
 
-            slider.LazyTravelTime = slider.NestedHitObjects[^1].StartTime - slider.StartTime;
+            // TODO: This commented version is actually correct by the new lazer implementation, but intentionally held back from
+            // difficulty calculator to preserve known behaviour.
+            // double trackingEndTime = Math.Max(
+            //     // SliderTailCircle always occurs at the final end time of the slider, but the player only needs to hold until within a lenience before it.
+            //     slider.Duration + SliderEventGenerator.TAIL_LENIENCY,
+            //     // There's an edge case where one or more ticks/repeats fall within that leniency range.
+            //     // In such a case, the player needs to track until the final tick or repeat.
+            //     slider.NestedHitObjects.LastOrDefault(n => n is not SliderTailCircle)?.StartTime ?? double.MinValue
+            // );
+
+            double trackingEndTime = Math.Max(
+                slider.StartTime + slider.Duration + SliderEventGenerator.TAIL_LENIENCY,
+                slider.StartTime + slider.Duration / 2
+            );
+
+            IList<HitObject> nestedObjects = slider.NestedHitObjects;
+
+            SliderTick? lastRealTick = slider.NestedHitObjects.OfType<SliderTick>().LastOrDefault();
+
+            if (lastRealTick?.StartTime > trackingEndTime)
+            {
+                trackingEndTime = lastRealTick.StartTime;
+
+                // When the last tick falls after the tracking end time, we need to re-sort the nested objects
+                // based on time. This creates a somewhat weird ordering which is counter to how a user would
+                // understand the slider, but allows a zero-diff with known diffcalc output.
+                //
+                // To reiterate, this is definitely not correct from a difficulty calculation perspective
+                // and should be revisited at a later date (likely by replacing this whole code with the commented
+                // version above).
+                List<HitObject> reordered = nestedObjects.ToList();
+
+                reordered.Remove(lastRealTick);
+                reordered.Add(lastRealTick);
+
+                nestedObjects = reordered;
+            }
+
+            slider.LazyTravelTime = trackingEndTime - slider.StartTime;
 
             double endTimeMin = slider.LazyTravelTime / slider.SpanDuration;
             if (endTimeMin % 2 >= 1)
@@ -223,12 +262,14 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Preprocessing
                 endTimeMin %= 1;
 
             slider.LazyEndPosition = slider.StackedPosition + slider.Path.PositionAt(endTimeMin); // temporary lazy end position until a real result can be derived.
-            var currCursorPosition = slider.StackedPosition;
+
+            Vector2 currCursorPosition = slider.StackedPosition;
+
             double scalingFactor = NORMALISED_RADIUS / slider.Radius; // lazySliderDistance is coded to be sensitive to scaling, this makes the maths easier with the thresholds being used.
 
-            for (int i = 1; i < slider.NestedHitObjects.Count; i++)
+            for (int i = 1; i < nestedObjects.Count; i++)
             {
-                var currMovementObj = (OsuHitObject)slider.NestedHitObjects[i];
+                var currMovementObj = (OsuHitObject)nestedObjects[i];
 
                 Vector2 currMovement = Vector2.Subtract(currMovementObj.StackedPosition, currCursorPosition);
                 double currMovementLength = scalingFactor * currMovement.Length;
@@ -236,7 +277,7 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Preprocessing
                 // Amount of movement required so that the cursor position needs to be updated.
                 double requiredMovement = assumed_slider_radius;
 
-                if (i == slider.NestedHitObjects.Count - 1)
+                if (i == nestedObjects.Count - 1)
                 {
                     // The end of a slider has special aim rules due to the relaxed time constraint on position.
                     // There is both a lazy end position as well as the actual end slider position. We assume the player takes the simpler movement.
@@ -263,7 +304,7 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Preprocessing
                     slider.LazyTravelDistance += (float)currMovementLength;
                 }
 
-                if (i == slider.NestedHitObjects.Count - 1)
+                if (i == nestedObjects.Count - 1)
                     slider.LazyEndPosition = currCursorPosition;
             }
         }

osu.Game.Rulesets.Osu/Mods/OsuModStrictTracking.cs

@@ -129,7 +129,7 @@ namespace osu.Game.Rulesets.Osu.Mods
                             });
                             break;
 
-                        case SliderEventType.LastTick:
+                        case SliderEventType.Tail:
                             AddNested(TailCircle = new StrictTrackingSliderTailCircle(this)
                             {
                                 RepeatIndex = e.SpanIndex,

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

@@ -264,7 +264,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 
         protected override void CheckForResult(bool userTriggered, double timeOffset)
         {
-            if (userTriggered || Time.Current < HitObject.EndTime)
+            if (userTriggered || !TailCircle.Judged || Time.Current < HitObject.EndTime)
                 return;
 
             // If only the nested hitobjects are judged, then the slider's own judgement is ignored for scoring purposes.

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSliderBall.cs

@@ -11,6 +11,7 @@ using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Input;
 using osu.Framework.Input.Events;
+using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Osu.Skinning.Default;
@@ -153,9 +154,12 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 
             Tracking =
                 // in valid time range
-                Time.Current >= drawableSlider.HitObject.StartTime && Time.Current < drawableSlider.HitObject.EndTime &&
+                Time.Current >= drawableSlider.HitObject.StartTime
+                // even in an edge case where current time has exceeded the slider's time, we may not have finished judging.
+                // we don't want to potentially update from Tracking=true to Tracking=false at this point.
+                && (!drawableSlider.AllJudged || Time.Current <= drawableSlider.HitObject.GetEndTime())
                 // in valid position range
-                lastScreenSpaceMousePosition.HasValue && followCircleReceptor.ReceivePositionalInputAt(lastScreenSpaceMousePosition.Value) &&
+                && lastScreenSpaceMousePosition.HasValue && followCircleReceptor.ReceivePositionalInputAt(lastScreenSpaceMousePosition.Value) &&
                 // valid action
                 (actions?.Any(isValidTrackingAction) ?? false);
 

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSliderTail.cs

@@ -8,6 +8,7 @@ using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Skinning;
@@ -125,8 +126,22 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 
         protected override void CheckForResult(bool userTriggered, double timeOffset)
         {
-            if (!userTriggered && timeOffset >= 0)
+            if (userTriggered)
-                ApplyResult(r => r.Type = Tracking ? r.Judgement.MaxResult : r.Judgement.MinResult);
+                return;
+
+            // Ensure the tail can only activate after all previous ticks already have.
+            //
+            // This covers the edge case where the lenience may allow the tail to activate before
+            // the last tick, changing ordering of score/combo awarding.
+            if (DrawableSlider.NestedHitObjects.Count > 1 && !DrawableSlider.NestedHitObjects[^2].Judged)
+                return;
+
+            // The player needs to have engaged in tracking at any point after the tail leniency cutoff.
+            // An actual tick miss should only occur if reaching the tick itself.
+            if (timeOffset >= SliderEventGenerator.TAIL_LENIENCY && Tracking)
+                ApplyResult(r => r.Type = r.Judgement.MaxResult);
+            else if (timeOffset > 0)
+                ApplyResult(r => r.Type = r.Judgement.MinResult);
         }
 
         protected override void OnApply()

osu.Game.Rulesets.Osu/Objects/Slider.cs

@@ -204,11 +204,7 @@ namespace osu.Game.Rulesets.Osu.Objects
                         });
                         break;
 
-                    case SliderEventType.LastTick:
+                    case SliderEventType.Tail:
-                        // Of note, we are directly mapping LastTick (instead of `SliderEventType.Tail`)  to SliderTailCircle.
-                        // It is required as difficulty calculation and gameplay relies on reading this value.
-                        // (although it is displayed in classic skins, which may be a concern).
-                        // If this is to change, we should revisit this.
                         AddNested(TailCircle = new SliderTailCircle(this)
                         {
                             RepeatIndex = e.SpanIndex,

osu.Game.Rulesets.Osu/Objects/SliderTailCircle.cs

@@ -2,16 +2,11 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Game.Rulesets.Judgements;
-using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Osu.Judgements;
 using osu.Game.Rulesets.Scoring;
 
 namespace osu.Game.Rulesets.Osu.Objects
 {
-    /// <summary>
-    /// Note that this should not be used for timing correctness.
-    /// See <see cref="SliderEventType.LastTick"/> usage in <see cref="Slider"/> for more information.
-    /// </summary>
     public class SliderTailCircle : SliderEndCircle
     {
         public SliderTailCircle(Slider slider)

osu.Game.Rulesets.Osu/Resources/Testing/Beatmaps/very-fast-slider.osu

@@ -0,0 +1,21 @@
+osu file format v128
+
+[Difficulty]
+HPDrainRate: 3
+CircleSize: 4
+OverallDifficulty: 9
+ApproachRate: 9.3
+SliderMultiplier: 3.59999990463257
+SliderTickRate: 1
+
+[TimingPoints]
+812,342.857142857143,4,1,1,70,1,0
+57383,-28.5714285714286,4,1,1,70,0,0
+
+[HitObjects]
+// Taken from https://osu.ppy.sh/beatmapsets/881996#osu/1844019
+// This slider is 42 ms in length, triggering the LegacyLastTick edge case.
+// The tick will be at 21.5 ms (sliderDuration / 2) instead of 6 ms (sliderDuration - LAST_TICK_LENIENCE).
+416,41,57383,6,0,L|467:217,1,157.499997329712,2|0,3:3|3:0,3:0:0:0:
+// Include the next slider as well to cover the jump back to the start position.
+407,73,57469,2,0,L|470:215,1,129.599999730835,2|0,0:0|0:0,0:0:0:0:

osu.Game.Tests/Beatmaps/SliderEventGenerationTest.cs

@@ -87,8 +87,8 @@ namespace osu.Game.Tests.Beatmaps
         {
             var events = SliderEventGenerator.Generate(start_time, span_duration, 1, span_duration / 2, span_duration, 1).ToArray();
 
-            Assert.That(events[2].Type, Is.EqualTo(SliderEventType.LastTick));
+            Assert.That(events[2].Type, Is.EqualTo(SliderEventType.LegacyLastTick));
-            Assert.That(events[2].Time, Is.EqualTo(span_duration + SliderEventGenerator.LAST_TICK_OFFSET));
+            Assert.That(events[2].Time, Is.EqualTo(span_duration + SliderEventGenerator.TAIL_LENIENCY));
         }
 
         [Test]

osu.Game/Rulesets/Objects/SliderEventGenerator.cs

@@ -16,8 +16,12 @@ namespace osu.Game.Rulesets.Objects
         /// until the true end of the slider. This very small amount of leniency makes it easier to jump away from fast sliders to the next hit object.
         ///
         /// After discussion on how this should be handled going forward, players have unanimously stated that this lenience should remain in some way.
+        /// These days, this is implemented in the drawable implementation of Slider in the osu! ruleset.
+        ///
+        /// We need to keep the <see cref="SliderEventType.LegacyLastTick"/> *only* for osu!catch conversion, which relies on it to generate tiny ticks
+        /// correctly.
         /// </summary>
-        public const double LAST_TICK_OFFSET = -36;
+        public const double TAIL_LENIENCY = -36;
 
         public static IEnumerable<SliderEventDescriptor> Generate(double startTime, double spanDuration, double velocity, double tickDistance, double totalDistance, int spanCount,
                                                                   CancellationToken cancellationToken = default)
@@ -84,18 +88,27 @@ namespace osu.Game.Rulesets.Objects
 
             int finalSpanIndex = spanCount - 1;
             double finalSpanStartTime = startTime + finalSpanIndex * spanDuration;
-            double finalSpanEndTime = Math.Max(startTime + totalDuration / 2, (finalSpanStartTime + spanDuration) + LAST_TICK_OFFSET);
-            double finalProgress = (finalSpanEndTime - finalSpanStartTime) / spanDuration;
 
-            if (spanCount % 2 == 0) finalProgress = 1 - finalProgress;
+            // Note that `finalSpanStartTime + spanDuration ≈ startTime + totalDuration`, but we write it like this to match floating point precision
+            // of stable.
+            //
+            // So thinking about this in a saner way, the time of the LegacyLastTick is
+            //
+            // `slider.StartTime + max(slider.Duration / 2, slider.Duration - 36)`
+            //
+            // As a slider gets shorter than 72 ms, the leniency offered falls below the 36 ms `TAIL_LENIENCY` constant.
+            double legacyLastTickTime = Math.Max(startTime + totalDuration / 2, (finalSpanStartTime + spanDuration) + TAIL_LENIENCY);
+            double legacyLastTickProgress = (legacyLastTickTime - finalSpanStartTime) / spanDuration;
+
+            if (spanCount % 2 == 0) legacyLastTickProgress = 1 - legacyLastTickProgress;
 
             yield return new SliderEventDescriptor
             {
-                Type = SliderEventType.LastTick,
+                Type = SliderEventType.LegacyLastTick,
                 SpanIndex = finalSpanIndex,
                 SpanStartTime = finalSpanStartTime,
-                Time = finalSpanEndTime,
+                Time = legacyLastTickTime,
-                PathProgress = finalProgress,
+                PathProgress = legacyLastTickProgress,
             };
 
             yield return new SliderEventDescriptor
@@ -183,9 +196,10 @@ namespace osu.Game.Rulesets.Objects
         Tick,
 
         /// <summary>
-        /// Occurs just before the tail. See <see cref="SliderEventGenerator.LAST_TICK_OFFSET"/>.
+        /// Occurs just before the tail. See <see cref="SliderEventGenerator.TAIL_LENIENCY"/>.
+        /// Should generally be ignored.
         /// </summary>
-        LastTick,
+        LegacyLastTick,
         Head,
         Tail,
         Repeat