osu!taiko star rating and performance points rebalance (#31338)

* rebalance

* revert pp scaling change

* further rebalancing

* comment

* adjust tests

osu.Game.Rulesets.Taiko.Tests/TaikoDifficultyCalculatorTest.cs

@@ -14,13 +14,13 @@ public class TaikoDifficultyCalculatorTest : DifficultyCalculatorTest
     {
         protected override string ResourceAssembly => "osu.Game.Rulesets.Taiko";
 
-        [TestCase(2.912326627861987d, 200, "diffcalc-test")]
-        [TestCase(2.912326627861987d, 200, "diffcalc-test-strong")]
+        [TestCase(3.3172381854905493d, 200, "diffcalc-test")]
+        [TestCase(3.3172381854905493d, 200, "diffcalc-test-strong")]
         public void Test(double expectedStarRating, int expectedMaxCombo, string name)
             => base.Test(expectedStarRating, expectedMaxCombo, name);
 
-        [TestCase(3.9339069955362014d, 200, "diffcalc-test")]
-        [TestCase(3.9339069955362014d, 200, "diffcalc-test-strong")]
+        [TestCase(4.4640702427013101d, 200, "diffcalc-test")]
+        [TestCase(4.4640702427013101d, 200, "diffcalc-test-strong")]
         public void TestClockRateAdjusted(double expectedStarRating, int expectedMaxCombo, string name)
             => Test(expectedStarRating, expectedMaxCombo, name, new TaikoModDoubleTime());
 

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

@@ -40,8 +40,8 @@ public class TaikoDifficultyAttributes : DifficultyAttributes
         [JsonProperty("mono_stamina_factor")]
         public double MonoStaminaFactor { get; set; }
 
-        [JsonProperty("reading_difficult_strains")]
-        public double ReadingTopStrains { get; set; }
+        [JsonProperty("rhythm_difficult_strains")]
+        public double RhythmTopStrains { get; set; }
 
         [JsonProperty("colour_difficult_strains")]
         public double ColourTopStrains { get; set; }

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

@@ -24,10 +24,13 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
     public class TaikoDifficultyCalculator : DifficultyCalculator
     {
         private const double difficulty_multiplier = 0.084375;
-        private const double rhythm_skill_multiplier = 1.24 * difficulty_multiplier;
+        private const double rhythm_skill_multiplier = 0.65 * difficulty_multiplier;
         private const double reading_skill_multiplier = 0.100 * difficulty_multiplier;
         private const double colour_skill_multiplier = 0.375 * difficulty_multiplier;
-        private const double stamina_skill_multiplier = 0.375 * difficulty_multiplier;
+        private const double stamina_skill_multiplier = 0.445 * difficulty_multiplier;
+
+        private double strainLengthBonus;
+        private double patternMultiplier;
 
         public override int Version => 20241007;
 
@@ -116,16 +119,24 @@ protected override DifficultyAttributes CreateDifficultyAttributes(IBeatmap beat
             double monoStaminaFactor = staminaRating == 0 ? 1 : Math.Pow(monoStaminaRating / staminaRating, 5);
 
             double colourDifficultStrains = colour.CountTopWeightedStrains();
-            double readingDifficultStrains = reading.CountTopWeightedStrains();
-            double staminaDifficultStrains = stamina.CountTopWeightedStrains();
+            double rhythmDifficultStrains = rhythm.CountTopWeightedStrains();
+            // Due to constraints of strain in cases where difficult strain values don't shift with range changes, we manually apply clockrate.
+            double staminaDifficultStrains = stamina.CountTopWeightedStrains() * clockRate;
+
+            // As we don't have pattern integration in osu!taiko, we apply the other two skills relative to rhythm.
+            patternMultiplier = Math.Pow(staminaRating * colourRating, 0.10);
+
+            strainLengthBonus = 1
+                                + Math.Min(Math.Max((staminaDifficultStrains - 1350) / 5000, 0), 0.15)
+                                + Math.Min(Math.Max((staminaRating - 7.0) / 1.0, 0), 0.05);
 
             double combinedRating = combinedDifficultyValue(rhythm, reading, colour, stamina, isRelax);
             double starRating = rescale(combinedRating * 1.4);
 
             // Converts are penalised outside the scope of difficulty calculation, as our assumptions surrounding standard play-styles becomes out-of-scope.
             if (beatmap.BeatmapInfo.Ruleset.OnlineID == 0)
             {
-                starRating *= 0.825;
+                starRating *= 0.7;
 
                 // For maps with relax, multiple inputs are more likely to be abused.
                 if (isRelax)
@@ -144,7 +155,7 @@ protected override DifficultyAttributes CreateDifficultyAttributes(IBeatmap beat
                 ColourDifficulty = colourRating,
                 StaminaDifficulty = staminaRating,
                 MonoStaminaFactor = monoStaminaFactor,
-                ReadingTopStrains = readingDifficultStrains,
+                RhythmTopStrains = rhythmDifficultStrains,
                 ColourTopStrains = colourDifficultStrains,
                 StaminaTopStrains = staminaDifficultStrains,
                 GreatHitWindow = hitWindows.WindowFor(HitResult.Great) / clockRate,
@@ -173,10 +184,10 @@ private double combinedDifficultyValue(Rhythm rhythm, Reading reading, Colour co
 
             for (int i = 0; i < colourPeaks.Count; i++)
             {
-                double rhythmPeak = rhythmPeaks[i] * rhythm_skill_multiplier;
+                double rhythmPeak = rhythmPeaks[i] * rhythm_skill_multiplier * patternMultiplier;
                 double readingPeak = readingPeaks[i] * reading_skill_multiplier;
                 double colourPeak = colourPeaks[i] * colour_skill_multiplier;
-                double staminaPeak = staminaPeaks[i] * stamina_skill_multiplier;
+                double staminaPeak = staminaPeaks[i] * stamina_skill_multiplier * strainLengthBonus;
 
                 if (isRelax)
                 {

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

@@ -73,8 +73,10 @@ protected override PerformanceAttributes CreatePerformanceAttributes(ScoreInfo s
 
         private double computeDifficultyValue(ScoreInfo score, TaikoDifficultyAttributes attributes)
         {
-            double baseDifficulty = 5 * Math.Max(1.0, attributes.StarRating / 0.115) - 4.0;
-            double difficultyValue = Math.Min(Math.Pow(baseDifficulty, 3) / 69052.51, Math.Pow(baseDifficulty, 2.25) / 1150.0);
+            double baseDifficulty = 5 * Math.Max(1.0, attributes.StarRating / 0.110) - 4.0;
+            double difficultyValue = Math.Min(Math.Pow(baseDifficulty, 3) / 69052.51, Math.Pow(baseDifficulty, 2.25) / 1250.0);
+
+            difficultyValue *= 1 + 0.10 * Math.Max(0, attributes.StarRating - 10);
 
             double lengthBonus = 1 + 0.1 * Math.Min(1.0, totalHits / 1500.0);
             difficultyValue *= lengthBonus;
@@ -95,7 +97,7 @@ private double computeDifficultyValue(ScoreInfo score, TaikoDifficultyAttributes
 
             // Scale accuracy more harshly on nearly-completely mono (single coloured) speed maps.
             double accScalingExponent = 2 + attributes.MonoStaminaFactor;
-            double accScalingShift = 400 - 100 * attributes.MonoStaminaFactor;
+            double accScalingShift = 500 - 100 * attributes.MonoStaminaFactor;
 
             return difficultyValue * Math.Pow(SpecialFunctions.Erf(accScalingShift / (Math.Sqrt(2) * estimatedUnstableRate.Value)), accScalingExponent);
         }