Extend Skill to include ObjectDifficulties (#36152)

* Extend `Skill` to include `ObjectDifficulties`

* Remove generic

* Change `ObjectDifficulties` to be modifiable by children skills

* Fix tests

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

@@ -54,14 +54,14 @@ namespace osu.Game.Rulesets.Osu.Difficulty.Skills
 
         public double RelevantNoteCount()
         {
-            if (ObjectStrains.Count == 0)
+            if (ObjectDifficulties.Count == 0)
                 return 0;
 
-            double maxStrain = ObjectStrains.Max();
+            double maxStrain = ObjectDifficulties.Max();
             if (maxStrain == 0)
                 return 0;
 
-            return ObjectStrains.Sum(strain => 1.0 / (1.0 + Math.Exp(-(strain / maxStrain * 12.0 - 6.0))));
+            return ObjectDifficulties.Sum(strain => 1.0 / (1.0 + Math.Exp(-(strain / maxStrain * 12.0 - 6.0))));
         }
 
         public double CountTopWeightedSliders(double difficultyValue)

osu.Game.Rulesets.Taiko/Difficulty/TaikoDifficultyCalculator.cs

@@ -186,10 +186,10 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
             }
 
             List<double> hitObjectStrainPeaks = combinePeaks(
-                rhythm.GetObjectStrains().ToList(),
-                reading.GetObjectStrains().ToList(),
-                colour.GetObjectStrains().ToList(),
-                stamina.GetObjectStrains().ToList()
+                rhythm.GetObjectDifficulties(),
+                reading.GetObjectDifficulties(),
+                colour.GetObjectDifficulties(),
+                stamina.GetObjectDifficulties()
             );
 
             if (hitObjectStrainPeaks.Count == 0)
@@ -211,7 +211,7 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
         /// <summary>
         /// Combines lists of peak strains from multiple skills into a list of single peak strains for each section.
         /// </summary>
-        private List<double> combinePeaks(List<double> rhythmPeaks, List<double> readingPeaks, List<double> colourPeaks, List<double> staminaPeaks)
+        private List<double> combinePeaks(IReadOnlyList<double> rhythmPeaks, IReadOnlyList<double> readingPeaks, IReadOnlyList<double> colourPeaks, IReadOnlyList<double> staminaPeaks)
         {
             var combinedPeaks = new List<double>();
 

osu.Game.Tests/NonVisual/TestSceneTimedDifficultyCalculation.cs

@@ -200,8 +200,9 @@ namespace osu.Game.Tests.NonVisual
                 {
                 }
 
-                public override void Process(DifficultyHitObject current)
+                protected override double ProcessInternal(DifficultyHitObject current)
                 {
+                    return 0;
                 }
 
                 public override double DifficultyValue() => 1;

osu.Game/Rulesets/Difficulty/Skills/Skill.cs

@@ -20,6 +20,11 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// </summary>
         protected IReadOnlyList<Mod> Mods => mods;
 
+        /// <summary>
+        /// List of calculated per-object difficulties, populated by Process
+        /// </summary>
+        protected readonly List<double> ObjectDifficulties = new List<double>();
+
         private readonly Mod[] mods;
 
         protected Skill(Mod[] mods)
@@ -31,11 +36,19 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// Process a <see cref="DifficultyHitObject"/>.
         /// </summary>
         /// <param name="current">The <see cref="DifficultyHitObject"/> to process.</param>
-        public abstract void Process(DifficultyHitObject current);
+        public void Process(DifficultyHitObject current)
+        {
+            double difficultyValue = ProcessInternal(current);
+            ObjectDifficulties.Add(difficultyValue);
+        }
+
+        protected abstract double ProcessInternal(DifficultyHitObject current);
 
         /// <summary>
         /// Returns the calculated difficulty value representing all <see cref="DifficultyHitObject"/>s that have been processed up to this point.
         /// </summary>
         public abstract double DifficultyValue();
+
+        public IReadOnlyList<double> GetObjectDifficulties() => ObjectDifficulties;
     }
 }

osu.Game/Rulesets/Difficulty/Skills/StrainSkill.cs

@@ -29,7 +29,6 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         private double currentSectionEnd;
 
         private readonly List<double> strainPeaks = new List<double>();
-        protected readonly List<double> ObjectStrains = new List<double>(); // Store individual strains
 
         protected StrainSkill(Mod[] mods)
             : base(mods)
@@ -44,7 +43,7 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// <summary>
         /// Process a <see cref="DifficultyHitObject"/> and update current strain values accordingly.
         /// </summary>
-        public sealed override void Process(DifficultyHitObject current)
+        protected sealed override double ProcessInternal(DifficultyHitObject current)
         {
             // The first object doesn't generate a strain, so we begin with an incremented section end
             if (current.Index == 0)
@@ -60,8 +59,7 @@ namespace osu.Game.Rulesets.Difficulty.Skills
             double strain = StrainValueAt(current);
             currentSectionPeak = Math.Max(strain, currentSectionPeak);
 
-            // Store the strain value for the object
-            ObjectStrains.Add(strain);
+            return strain;
         }
 
         /// <summary>
@@ -70,16 +68,16 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// </summary>
         public virtual double CountTopWeightedStrains(double difficultyValue)
         {
-            if (ObjectStrains.Count == 0)
+            if (ObjectDifficulties.Count == 0)
                 return 0.0;
 
             double consistentTopStrain = difficultyValue * (1 - DecayWeight); // What would the top strain be if all strain values were identical
 
             if (consistentTopStrain == 0)
-                return ObjectStrains.Count;
+                return ObjectDifficulties.Count;
 
             // Use a weighted sum of all strains. Constants are arbitrary and give nice values
-            return ObjectStrains.Sum(s => 1.1 / (1 + Math.Exp(-10 * (s / consistentTopStrain - 0.88))));
+            return ObjectDifficulties.Sum(s => 1.1 / (1 + Math.Exp(-10 * (s / consistentTopStrain - 0.88))));
         }
 
         /// <summary>
@@ -116,8 +114,6 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// </summary>
         public IEnumerable<double> GetCurrentStrainPeaks() => strainPeaks.Append(currentSectionPeak);
 
-        public IEnumerable<double> GetObjectStrains() => ObjectStrains;
-
         /// <summary>
         /// Returns the calculated difficulty value representing all <see cref="DifficultyHitObject"/>s that have been processed up to this point.
         /// </summary>