Improve convert considerations in osu!taiko (#31546)

* return a higher finger count

* implement isConvert

* diffcalc cleanup

* harshen monostaminafactor accuracy curve

* readd comment

* adjusts tests

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

@@ -14,13 +14,13 @@ namespace osu.Game.Rulesets.Taiko.Tests
     {
         protected override string ResourceAssembly => "osu.Game.Rulesets.Taiko";
 
-        [TestCase(3.3167800835687551d, 200, "diffcalc-test")]
-        [TestCase(3.3167800835687551d, 200, "diffcalc-test-strong")]
+        [TestCase(3.3056113401782845d, 200, "diffcalc-test")]
+        [TestCase(3.3056113401782845d, 200, "diffcalc-test-strong")]
         public void Test(double expectedStarRating, int expectedMaxCombo, string name)
             => base.Test(expectedStarRating, expectedMaxCombo, name);
 
-        [TestCase(4.4631326105105122d, 200, "diffcalc-test")]
-        [TestCase(4.4631326105105122d, 200, "diffcalc-test-strong")]
+        [TestCase(4.4473902679506896d, 200, "diffcalc-test")]
+        [TestCase(4.4473902679506896d, 200, "diffcalc-test-strong")]
         public void TestClockRateAdjusted(double expectedStarRating, int expectedMaxCombo, string name)
             => Test(expectedStarRating, expectedMaxCombo, name, new TaikoModDoubleTime());
 

osu.Game.Rulesets.Taiko/Difficulty/Evaluators/StaminaEvaluator.cs

@@ -42,7 +42,7 @@ namespace osu.Game.Rulesets.Taiko.Difficulty.Evaluators
                 return 2;
             }
 
-            return 4;
+            return 8;
         }
 
         /// <summary>

osu.Game.Rulesets.Taiko/Difficulty/Skills/Stamina.cs

@@ -20,6 +20,7 @@ namespace osu.Game.Rulesets.Taiko.Difficulty.Skills
         private double strainDecayBase => 0.4;
 
         private readonly bool singleColourStamina;
+        private readonly bool isConvert;
 
         private double currentStrain;
 
@@ -28,10 +29,12 @@ namespace osu.Game.Rulesets.Taiko.Difficulty.Skills
         /// </summary>
         /// <param name="mods">Mods for use in skill calculations.</param>
         /// <param name="singleColourStamina">Reads when Stamina is from a single coloured pattern.</param>
-        public Stamina(Mod[] mods, bool singleColourStamina)
+        /// <param name="isConvert">Determines if the currently evaluated beatmap is converted.</param>
+        public Stamina(Mod[] mods, bool singleColourStamina, bool isConvert)
             : base(mods)
         {
             this.singleColourStamina = singleColourStamina;
+            this.isConvert = isConvert;
         }
 
         private double strainDecay(double ms) => Math.Pow(strainDecayBase, ms / 1000);
@@ -45,7 +48,7 @@ namespace osu.Game.Rulesets.Taiko.Difficulty.Skills
             var currentObject = current as TaikoDifficultyHitObject;
             int index = currentObject?.Colour.MonoStreak?.HitObjects.IndexOf(currentObject) ?? 0;
 
-            double monolengthBonus = 1 + Math.Min(Math.Max((index - 5) / 50.0, 0), 0.30);
+            double monolengthBonus = isConvert ? 1 : 1 + Math.Min(Math.Max((index - 5) / 50.0, 0), 0.30);
 
             if (singleColourStamina)
                 return DifficultyCalculationUtils.Logistic(-(index - 10) / 2.0, currentStrain);

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

@@ -32,6 +32,8 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
         private double strainLengthBonus;
         private double patternMultiplier;
 
+        private bool isConvert;
+
         public override int Version => 20241007;
 
         public TaikoDifficultyCalculator(IRulesetInfo ruleset, IWorkingBeatmap beatmap)
@@ -44,13 +46,15 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
             HitWindows hitWindows = new HitWindows();
             hitWindows.SetDifficulty(beatmap.Difficulty.OverallDifficulty);
 
+            isConvert = beatmap.BeatmapInfo.Ruleset.OnlineID == 0;
+
             return new Skill[]
             {
                 new Rhythm(mods, hitWindows.WindowFor(HitResult.Great) / clockRate),
                 new Reading(mods),
                 new Colour(mods),
-                new Stamina(mods, false),
-                new Stamina(mods, true)
+                new Stamina(mods, false, isConvert),
+                new Stamina(mods, true, isConvert)
             };
         }
 
@@ -130,19 +134,9 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
                                 + 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 combinedRating = combinedDifficultyValue(rhythm, reading, colour, stamina, isRelax, isConvert);
             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 *= 0.7;
-
-                // For maps with relax, multiple inputs are more likely to be abused.
-                if (isRelax)
-                    starRating *= 0.60;
-            }
-
             HitWindows hitWindows = new TaikoHitWindows();
             hitWindows.SetDifficulty(beatmap.Difficulty.OverallDifficulty);
 
@@ -173,7 +167,7 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
         /// For each section, the peak strains of all separate skills are combined into a single peak strain for the section.
         /// The resulting partial rating of the beatmap is a weighted sum of the combined peaks (higher peaks are weighted more).
         /// </remarks>
-        private double combinedDifficultyValue(Rhythm rhythm, Reading reading, Colour colour, Stamina stamina, bool isRelax)
+        private double combinedDifficultyValue(Rhythm rhythm, Reading reading, Colour colour, Stamina stamina, bool isRelax, bool isConvert)
         {
             List<double> peaks = new List<double>();
 
@@ -186,14 +180,9 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
             {
                 double rhythmPeak = rhythmPeaks[i] * rhythm_skill_multiplier * patternMultiplier;
                 double readingPeak = readingPeaks[i] * reading_skill_multiplier;
-                double colourPeak = colourPeaks[i] * colour_skill_multiplier;
+                double colourPeak = isRelax ? 0 : colourPeaks[i] * colour_skill_multiplier; // There is no colour difficulty in relax.
                 double staminaPeak = staminaPeaks[i] * stamina_skill_multiplier * strainLengthBonus;
-
-                if (isRelax)
-                {
-                    colourPeak = 0; // There is no colour difficulty in relax.
-                    staminaPeak /= 1.5; // Stamina difficulty is decreased with an increased available finger count.
-                }
+                staminaPeak /= isConvert || isRelax ? 1.5 : 1.0; // Available finger count is increased by 150%, thus we adjust accordingly.
 
                 double peak = DifficultyCalculationUtils.Norm(2, DifficultyCalculationUtils.Norm(1.5, colourPeak, staminaPeak), rhythmPeak, readingPeak);
 

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

@@ -97,7 +97,7 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
 
             // Scale accuracy more harshly on nearly-completely mono (single coloured) speed maps.
             double accScalingExponent = 2 + attributes.MonoStaminaFactor;
-            double accScalingShift = 500 - 100 * attributes.MonoStaminaFactor;
+            double accScalingShift = 500 - 100 * (attributes.MonoStaminaFactor * 3);
 
             return difficultyValue * Math.Pow(DifficultyCalculationUtils.Erf(accScalingShift / (Math.Sqrt(2) * estimatedUnstableRate.Value)), accScalingExponent);
         }