Combine mania skills

osu.Game.Rulesets.Mania/Difficulty/ManiaDifficultyCalculator.cs

@@ -40,7 +40,7 @@ namespace osu.Game.Rulesets.Mania.Difficulty
 
             return new ManiaDifficultyAttributes
             {
-                StarRating = difficultyValue(skills) * star_scaling_factor,
+                StarRating = skills[0].DifficultyValue() * star_scaling_factor,
                 Mods = mods,
                 // Todo: This int cast is temporary to achieve 1:1 results with osu!stable, and should be removed in the future
                 GreatHitWindow = (int)(hitWindows.WindowFor(HitResult.Great)) / clockRate,
@@ -49,55 +49,16 @@ namespace osu.Game.Rulesets.Mania.Difficulty
             };
         }
 
-        private double difficultyValue(Skill[] skills)
-        {
-            // Preprocess the strains to find the maximum overall + individual (aggregate) strain from each section
-            var overall = skills.OfType<Overall>().Single();
-            var aggregatePeaks = new List<double>(Enumerable.Repeat(0.0, overall.StrainPeaks.Count));
-
-            foreach (var individual in skills.OfType<Individual>())
-            {
-                for (int i = 0; i < individual.StrainPeaks.Count; i++)
-                {
-                    double aggregate = individual.StrainPeaks[i] + overall.StrainPeaks[i];
-
-                    if (aggregate > aggregatePeaks[i])
-                        aggregatePeaks[i] = aggregate;
-                }
-            }
-
-            aggregatePeaks.Sort((a, b) => b.CompareTo(a)); // Sort from highest to lowest strain.
-
-            double difficulty = 0;
-            double weight = 1;
-
-            // Difficulty is the weighted sum of the highest strains from every section.
-            foreach (double strain in aggregatePeaks)
-            {
-                difficulty += strain * weight;
-                weight *= 0.9;
-            }
-
-            return difficulty;
-        }
-
         protected override IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate)
         {
             for (int i = 1; i < beatmap.HitObjects.Count; i++)
                 yield return new ManiaDifficultyHitObject(beatmap.HitObjects[i], beatmap.HitObjects[i - 1], clockRate);
         }
 
-        protected override Skill[] CreateSkills(IBeatmap beatmap)
+        protected override Skill[] CreateSkills(IBeatmap beatmap) => new Skill[]
         {
-            int columnCount = ((ManiaBeatmap)beatmap).TotalColumns;
+            new Strain(((ManiaBeatmap)beatmap).TotalColumns)
-
+        };
-            var skills = new List<Skill> { new Overall(columnCount) };
-
-            for (int i = 0; i < columnCount; i++)
-                skills.Add(new Individual(i, columnCount));
-
-            return skills.ToArray();
-        }
 
         protected override Mod[] DifficultyAdjustmentMods
         {

osu.Game.Rulesets.Mania/Difficulty/Skills/Individual.cs

@@ -1,47 +0,0 @@
-// 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 System.Linq;
-using osu.Game.Rulesets.Difficulty.Preprocessing;
-using osu.Game.Rulesets.Difficulty.Skills;
-using osu.Game.Rulesets.Mania.Difficulty.Preprocessing;
-using osu.Game.Rulesets.Objects;
-
-namespace osu.Game.Rulesets.Mania.Difficulty.Skills
-{
-    public class Individual : Skill
-    {
-        protected override double SkillMultiplier => 1;
-        protected override double StrainDecayBase => 0.125;
-
-        private readonly double[] holdEndTimes;
-
-        private readonly int column;
-
-        public Individual(int column, int columnCount)
-        {
-            this.column = column;
-
-            holdEndTimes = new double[columnCount];
-        }
-
-        protected override double StrainValueOf(DifficultyHitObject current)
-        {
-            var maniaCurrent = (ManiaDifficultyHitObject)current;
-            var endTime = maniaCurrent.BaseObject.GetEndTime();
-
-            try
-            {
-                if (maniaCurrent.BaseObject.Column != column)
-                    return 0;
-
-                // We give a slight bonus if something is held meanwhile
-                return holdEndTimes.Any(t => t > endTime) ? 2.5 : 2;
-            }
-            finally
-            {
-                holdEndTimes[maniaCurrent.BaseObject.Column] = endTime;
-            }
-        }
-    }
-}

osu.Game.Rulesets.Mania/Difficulty/Skills/Overall.cs

@@ -1,56 +0,0 @@
-// 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.Game.Rulesets.Difficulty.Preprocessing;
-using osu.Game.Rulesets.Difficulty.Skills;
-using osu.Game.Rulesets.Mania.Difficulty.Preprocessing;
-using osu.Game.Rulesets.Objects;
-
-namespace osu.Game.Rulesets.Mania.Difficulty.Skills
-{
-    public class Overall : Skill
-    {
-        protected override double SkillMultiplier => 1;
-        protected override double StrainDecayBase => 0.3;
-
-        private readonly double[] holdEndTimes;
-
-        private readonly int columnCount;
-
-        public Overall(int columnCount)
-        {
-            this.columnCount = columnCount;
-
-            holdEndTimes = new double[columnCount];
-        }
-
-        protected override double StrainValueOf(DifficultyHitObject current)
-        {
-            var maniaCurrent = (ManiaDifficultyHitObject)current;
-            var endTime = maniaCurrent.BaseObject.GetEndTime();
-
-            double holdFactor = 1.0; // Factor in case something else is held
-            double holdAddition = 0; // Addition to the current note in case it's a hold and has to be released awkwardly
-
-            for (int i = 0; i < columnCount; i++)
-            {
-                // If there is at least one other overlapping end or note, then we get an addition, buuuuuut...
-                if (current.BaseObject.StartTime < holdEndTimes[i] && endTime > holdEndTimes[i])
-                    holdAddition = 1.0;
-
-                // ... this addition only is valid if there is _no_ other note with the same ending.
-                // Releasing multiple notes at the same time is just as easy as releasing one
-                if (endTime == holdEndTimes[i])
-                    holdAddition = 0;
-
-                // We give a slight bonus if something is held meanwhile
-                if (holdEndTimes[i] > endTime)
-                    holdFactor = 1.25;
-            }
-
-            holdEndTimes[maniaCurrent.BaseObject.Column] = endTime;
-
-            return (1 + holdAddition) * holdFactor;
-        }
-    }
-}

osu.Game.Rulesets.Mania/Difficulty/Skills/Strain.cs

@@ -0,0 +1,80 @@
+// 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 System;
+using osu.Framework.Utils;
+using osu.Game.Rulesets.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Difficulty.Skills;
+using osu.Game.Rulesets.Mania.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Objects;
+
+namespace osu.Game.Rulesets.Mania.Difficulty.Skills
+{
+    public class Strain : Skill
+    {
+        private const double individual_decay_base = 0.125;
+        private const double overall_decay_base = 0.30;
+
+        protected override double SkillMultiplier => 1;
+        protected override double StrainDecayBase => 1;
+
+        private readonly double[] holdEndTimes;
+        private readonly double[] individualStrains;
+
+        private double individualStrain;
+        private double overallStrain;
+
+        public Strain(int totalColumns)
+        {
+            holdEndTimes = new double[totalColumns];
+            individualStrains = new double[totalColumns];
+            overallStrain = 1;
+        }
+
+        protected override double StrainValueOf(DifficultyHitObject current)
+        {
+            var maniaCurrent = (ManiaDifficultyHitObject)current;
+            var endTime = maniaCurrent.BaseObject.GetEndTime();
+            var column = maniaCurrent.BaseObject.Column;
+
+            double holdFactor = 1.0; // Factor to all additional strains in case something else is held
+            double holdAddition = 0; // Addition to the current note in case it's a hold and has to be released awkwardly
+
+            // Fill up the holdEndTimes array
+            for (int i = 0; i < holdEndTimes.Length; ++i)
+            {
+                // If there is at least one other overlapping end or note, then we get an addition, buuuuuut...
+                if (Precision.DefinitelyBigger(holdEndTimes[i], maniaCurrent.BaseObject.StartTime, 1) && Precision.DefinitelyBigger(endTime, holdEndTimes[i], 1))
+                    holdAddition = 1.0;
+
+                // ... this addition only is valid if there is _no_ other note with the same ending. Releasing multiple notes at the same time is just as easy as releasing 1
+                if (Precision.AlmostEquals(endTime, holdEndTimes[i], 1))
+                    holdAddition = 0;
+
+                // We give a slight bonus to everything if something is held meanwhile
+                if (Precision.DefinitelyBigger(holdEndTimes[i], endTime, 1))
+                    holdFactor = 1.25;
+
+                // Decay individual strains
+                individualStrains[i] = applyDecay(individualStrains[i], current.DeltaTime, individual_decay_base);
+            }
+
+            holdEndTimes[column] = endTime;
+
+            // Increase individual strain in own column
+            individualStrains[column] += 2.0 * holdFactor;
+            individualStrain = individualStrains[column];
+
+            overallStrain = applyDecay(overallStrain, current.DeltaTime, overall_decay_base) + (1 + holdAddition) * holdFactor;
+
+            return individualStrain + overallStrain - CurrentStrain;
+        }
+
+        protected override double GetPeakStrain(double offset)
+            => applyDecay(individualStrain, offset - Previous[0].BaseObject.StartTime, individual_decay_base)
+               + applyDecay(overallStrain, offset - Previous[0].BaseObject.StartTime, overall_decay_base);
+
+        private double applyDecay(double value, double deltaTime, double decayBase)
+            => value * Math.Pow(decayBase, deltaTime / 1000);
+    }
+}