Implement IHasCurve on DrumRoll

osu.Game.Rulesets.Taiko/Beatmaps/TaikoBeatmapConverter.cs

@@ -19,7 +19,7 @@ namespace osu.Game.Rulesets.Taiko.Beatmaps
         /// osu! is generally slower than taiko, so a factor is added to increase
         /// speed. This must be used everywhere slider length or beat length is used.
         /// </summary>
-        private const float legacy_velocity_multiplier = 1.4f;
+        public const float LEGACY_VELOCITY_MULTIPLIER = 1.4f;
 
         /// <summary>
         /// Because swells are easier in taiko than spinners are in osu!,
@@ -52,7 +52,7 @@ namespace osu.Game.Rulesets.Taiko.Beatmaps
             // Rewrite the beatmap info to add the slider velocity multiplier
             original.BeatmapInfo = original.BeatmapInfo.Clone();
             original.BeatmapInfo.BaseDifficulty = original.BeatmapInfo.BaseDifficulty.Clone();
-            original.BeatmapInfo.BaseDifficulty.SliderMultiplier *= legacy_velocity_multiplier;
+            original.BeatmapInfo.BaseDifficulty.SliderMultiplier *= LEGACY_VELOCITY_MULTIPLIER;
 
             Beatmap<TaikoHitObject> converted = base.ConvertBeatmap(original);
 
@@ -92,7 +92,7 @@ namespace osu.Game.Rulesets.Taiko.Beatmaps
                     double speedAdjustedBeatLength = timingPoint.BeatLength / speedAdjustment;
 
                     // The true distance, accounting for any repeats. This ends up being the drum roll distance later
-                    double distance = distanceData.Distance * spans * legacy_velocity_multiplier;
+                    double distance = distanceData.Distance * spans * LEGACY_VELOCITY_MULTIPLIER;
 
                     // The velocity of the taiko hit object - calculated as the velocity of a drum roll
                     double taikoVelocity = taiko_base_distance * beatmap.BeatmapInfo.BaseDifficulty.SliderMultiplier / speedAdjustedBeatLength;

osu.Game.Rulesets.Taiko/Objects/DrumRoll.cs

@@ -3,15 +3,20 @@
 
 using osu.Game.Rulesets.Objects.Types;
 using System;
+using System.Collections.Generic;
+using osu.Game.Audio;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Rulesets.Judgements;
+using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Scoring;
+using osu.Game.Rulesets.Taiko.Beatmaps;
 using osu.Game.Rulesets.Taiko.Judgements;
+using osuTK;
 
 namespace osu.Game.Rulesets.Taiko.Objects
 {
-    public class DrumRoll : TaikoHitObject, IHasEndTime
+    public class DrumRoll : TaikoHitObject, IHasEndTime, IHasCurve
     {
         /// <summary>
         /// Drum roll distance that results in a duration of 1 speed-adjusted beat length.
@@ -26,6 +31,11 @@ namespace osu.Game.Rulesets.Taiko.Objects
 
         public double Duration { get; set; }
 
+        /// <summary>
+        /// Velocity of this <see cref="DrumRoll"/>.
+        /// </summary>
+        public double Velocity { get; private set; }
+
         /// <summary>
         /// Numer of ticks per beat length.
         /// </summary>
@@ -54,6 +64,10 @@ namespace osu.Game.Rulesets.Taiko.Objects
             base.ApplyDefaultsToSelf(controlPointInfo, difficulty);
 
             TimingControlPoint timingPoint = controlPointInfo.TimingPointAt(StartTime);
+            DifficultyControlPoint difficultyPoint = controlPointInfo.DifficultyPointAt(StartTime);
+
+            double scoringDistance = base_distance * difficulty.SliderMultiplier * difficultyPoint.SpeedMultiplier;
+            Velocity = scoringDistance / timingPoint.BeatLength;
 
             tickSpacing = timingPoint.BeatLength / TickRate;
             overallDifficulty = difficulty.OverallDifficulty;
@@ -93,5 +107,18 @@ namespace osu.Game.Rulesets.Taiko.Objects
         public override Judgement CreateJudgement() => new TaikoDrumRollJudgement();
 
         protected override HitWindows CreateHitWindows() => HitWindows.Empty;
+
+        #region LegacyBeatmapEncoder
+
+        double IHasDistance.Distance => Duration * Velocity;
+
+        int IHasRepeats.RepeatCount { get => 0; set { } }
+
+        List<IList<HitSampleInfo>> IHasRepeats.NodeSamples => new List<IList<HitSampleInfo>>();
+
+        SliderPath IHasCurve.Path
+            => new SliderPath(PathType.Linear, new[] { Vector2.Zero, new Vector2(1) }, ((IHasDistance)this).Distance / TaikoBeatmapConverter.LEGACY_VELOCITY_MULTIPLIER);
+
+        #endregion
     }
 }

osu.Game/Beatmaps/Formats/LegacyBeatmapEncoder.cs

@@ -125,7 +125,12 @@ namespace osu.Game.Beatmaps.Formats
             writer.WriteLine(FormattableString.Invariant($"CircleSize: {beatmap.BeatmapInfo.BaseDifficulty.CircleSize}"));
             writer.WriteLine(FormattableString.Invariant($"OverallDifficulty: {beatmap.BeatmapInfo.BaseDifficulty.OverallDifficulty}"));
             writer.WriteLine(FormattableString.Invariant($"ApproachRate: {beatmap.BeatmapInfo.BaseDifficulty.ApproachRate}"));
-            writer.WriteLine(FormattableString.Invariant($"SliderMultiplier: {beatmap.BeatmapInfo.BaseDifficulty.SliderMultiplier}"));
+
+            // Taiko adjusts the slider multiplier (see: TaikoBeatmapConverter.LEGACY_VELOCITY_MULTIPLIER)
+            writer.WriteLine(beatmap.BeatmapInfo.RulesetID == 1
+                ? FormattableString.Invariant($"SliderMultiplier: {beatmap.BeatmapInfo.BaseDifficulty.SliderMultiplier / 1.4f}")
+                : FormattableString.Invariant($"SliderMultiplier: {beatmap.BeatmapInfo.BaseDifficulty.SliderMultiplier}"));
+
             writer.WriteLine(FormattableString.Invariant($"SliderTickRate: {beatmap.BeatmapInfo.BaseDifficulty.SliderTickRate}"));
         }
 
@@ -226,7 +231,6 @@ namespace osu.Game.Beatmaps.Formats
             writer.Write(FormattableString.Invariant($"{position.Y},"));
             writer.Write(FormattableString.Invariant($"{hitObject.StartTime},"));
             writer.Write(FormattableString.Invariant($"{(int)getObjectType(hitObject)},"));
-
             writer.Write(FormattableString.Invariant($"{(int)toLegacyHitSoundType(hitObject.Samples)},"));
 
             if (hitObject is IHasCurve curveData)