Merge pull request #14617 from apollo-dw/speedpp

Remove speed caps in osu! difficulty calculation

osu.Game.Rulesets.Osu/Difficulty/OsuDifficultyCalculator.cs

@@ -21,6 +21,7 @@ namespace osu.Game.Rulesets.Osu.Difficulty
     public class OsuDifficultyCalculator : DifficultyCalculator
     {
         private const double difficulty_multiplier = 0.0675;
+        private double hitWindowGreat;
 
         public OsuDifficultyCalculator(Ruleset ruleset, WorkingBeatmap beatmap)
             : base(ruleset, beatmap)
@@ -52,11 +53,6 @@ namespace osu.Game.Rulesets.Osu.Difficulty
 
             double starRating = basePerformance > 0.00001 ? Math.Cbrt(1.12) * 0.027 * (Math.Cbrt(100000 / Math.Pow(2, 1 / 1.1) * basePerformance) + 4) : 0;
 
-            HitWindows hitWindows = new OsuHitWindows();
-            hitWindows.SetDifficulty(beatmap.BeatmapInfo.BaseDifficulty.OverallDifficulty);
-
-            // Todo: These int casts are temporary to achieve 1:1 results with osu!stable, and should be removed in the future
-            double hitWindowGreat = (int)(hitWindows.WindowFor(HitResult.Great)) / clockRate;
             double preempt = (int)BeatmapDifficulty.DifficultyRange(beatmap.BeatmapInfo.BaseDifficulty.ApproachRate, 1800, 1200, 450) / clockRate;
 
             int maxCombo = beatmap.HitObjects.Count;
@@ -96,12 +92,21 @@ namespace osu.Game.Rulesets.Osu.Difficulty
             }
         }
 
-        protected override Skill[] CreateSkills(IBeatmap beatmap, Mod[] mods, double clockRate) => new Skill[]
+        protected override Skill[] CreateSkills(IBeatmap beatmap, Mod[] mods, double clockRate)
         {
-            new Aim(mods),
+            HitWindows hitWindows = new OsuHitWindows();
-            new Speed(mods),
+            hitWindows.SetDifficulty(beatmap.BeatmapInfo.BaseDifficulty.OverallDifficulty);
-            new Flashlight(mods)
+
-        };
+            // Todo: These int casts are temporary to achieve 1:1 results with osu!stable, and should be removed in the future
+            hitWindowGreat = (int)(hitWindows.WindowFor(HitResult.Great)) / clockRate;
+
+            return new Skill[]
+            {
+                new Aim(mods),
+                new Speed(mods, hitWindowGreat),
+                new Flashlight(mods)
+            };
+        }
 
         protected override Mod[] DifficultyAdjustmentMods => new Mod[]
         {

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

@@ -16,6 +16,11 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Preprocessing
 
         protected new OsuHitObject BaseObject => (OsuHitObject)base.BaseObject;
 
+        /// <summary>
+        /// Milliseconds elapsed since the start time of the previous <see cref="OsuDifficultyHitObject"/>, with a minimum of 25ms to account for simultaneous <see cref="OsuDifficultyHitObject"/>s.
+        /// </summary>
+        public double StrainTime { get; private set; }
+
         /// <summary>
         /// Normalized distance from the end position of the previous <see cref="OsuDifficultyHitObject"/> to the start position of this <see cref="OsuDifficultyHitObject"/>.
         /// </summary>
@@ -32,11 +37,6 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Preprocessing
         /// </summary>
         public double? Angle { get; private set; }
 
-        /// <summary>
-        /// Milliseconds elapsed since the start time of the previous <see cref="OsuDifficultyHitObject"/>, with a minimum of 50ms.
-        /// </summary>
-        public readonly double StrainTime;
-
         private readonly OsuHitObject lastLastObject;
         private readonly OsuHitObject lastObject;
 
@@ -48,8 +48,8 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Preprocessing
 
             setDistances();
 
-            // Every strain interval is hard capped at the equivalent of 375 BPM streaming speed as a safety measure
+            // Capped to 25ms to prevent difficulty calculation breaking from simulatenous objects.
-            StrainTime = Math.Max(50, DeltaTime);
+            StrainTime = Math.Max(DeltaTime, 25);
         }
 
         private void setDistances()

osu.Game.Rulesets.Osu/Difficulty/Skills/Speed.cs

@@ -6,6 +6,7 @@ using osu.Game.Rulesets.Difficulty.Preprocessing;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Osu.Difficulty.Preprocessing;
 using osu.Game.Rulesets.Osu.Objects;
+using osu.Framework.Utils;
 
 namespace osu.Game.Rulesets.Osu.Difficulty.Skills
 {
@@ -26,12 +27,14 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Skills
         protected override double DifficultyMultiplier => 1.04;
 
         private const double min_speed_bonus = 75; // ~200BPM
-        private const double max_speed_bonus = 45; // ~330BPM
         private const double speed_balancing_factor = 40;
 
-        public Speed(Mod[] mods)
+        private readonly double greatWindow;
+
+        public Speed(Mod[] mods, double hitWindowGreat)
             : base(mods)
         {
+            greatWindow = hitWindowGreat;
         }
 
         protected override double StrainValueOf(DifficultyHitObject current)
@@ -40,13 +43,25 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Skills
                 return 0;
 
             var osuCurrent = (OsuDifficultyHitObject)current;
+            var osuPrevious = Previous.Count > 0 ? (OsuDifficultyHitObject)Previous[0] : null;
 
             double distance = Math.Min(single_spacing_threshold, osuCurrent.TravelDistance + osuCurrent.JumpDistance);
-            double deltaTime = Math.Max(max_speed_bonus, current.DeltaTime);
+            double strainTime = osuCurrent.StrainTime;
+
+            double greatWindowFull = greatWindow * 2;
+            double speedWindowRatio = strainTime / greatWindowFull;
+
+            // Aim to nerf cheesy rhythms (Very fast consecutive doubles with large deltatimes between)
+            if (osuPrevious != null && strainTime < greatWindowFull && osuPrevious.StrainTime > strainTime)
+                strainTime = Interpolation.Lerp(osuPrevious.StrainTime, strainTime, speedWindowRatio);
+
+            // Cap deltatime to the OD 300 hitwindow.
+            // 0.93 is derived from making sure 260bpm OD8 streams aren't nerfed harshly, whilst 0.92 limits the effect of the cap.
+            strainTime /= Math.Clamp((strainTime / greatWindowFull) / 0.93, 0.92, 1);
 
             double speedBonus = 1.0;
-            if (deltaTime < min_speed_bonus)
+            if (strainTime < min_speed_bonus)
-                speedBonus = 1 + Math.Pow((min_speed_bonus - deltaTime) / speed_balancing_factor, 2);
+                speedBonus = 1 + Math.Pow((min_speed_bonus - strainTime) / speed_balancing_factor, 2);
 
             double angleBonus = 1.0;
 
@@ -64,7 +79,10 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Skills
                 }
             }
 
-            return (1 + (speedBonus - 1) * 0.75) * angleBonus * (0.95 + speedBonus * Math.Pow(distance / single_spacing_threshold, 3.5)) / osuCurrent.StrainTime;
+            return (1 + (speedBonus - 1) * 0.75)
+                   * angleBonus
+                   * (0.95 + speedBonus * Math.Pow(distance / single_spacing_threshold, 3.5))
+                   / strainTime;
         }
     }
 }