Merge pull request #2557 from smoogipoo/mania-performance-calculator

Implement osu!mania performance calculator

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

@@ -59,7 +59,8 @@ namespace osu.Game.Rulesets.Mania.Difficulty
 
             double starRating = calculateDifficulty() * star_scaling_factor;
 
-            categoryDifficulty?.Add("Strain", starRating);
+            if (categoryDifficulty != null)
+                categoryDifficulty["Strain"] = starRating;
 
             return starRating;
         }

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

@@ -0,0 +1,126 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets.Difficulty;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Scoring;
+
+namespace osu.Game.Rulesets.Mania.Difficulty
+{
+    public class ManiaPerformanceCalculator : PerformanceCalculator
+    {
+        private Mod[] mods;
+
+        // Score after being scaled by non-difficulty-increasing mods
+        private double scaledScore;
+
+        private int countPerfect;
+        private int countGreat;
+        private int countGood;
+        private int countOk;
+        private int countMeh;
+        private int countMiss;
+
+        public ManiaPerformanceCalculator(Ruleset ruleset, IBeatmap beatmap, Score score)
+            : base(ruleset, beatmap, score)
+        {
+        }
+
+        public override double Calculate(Dictionary<string, double> categoryDifficulty = null)
+        {
+            mods = Score.Mods;
+            scaledScore = Score.TotalScore;
+            countPerfect = Convert.ToInt32(Score.Statistics[HitResult.Perfect]);
+            countGreat = Convert.ToInt32(Score.Statistics[HitResult.Great]);
+            countGood = Convert.ToInt32(Score.Statistics[HitResult.Good]);
+            countOk = Convert.ToInt32(Score.Statistics[HitResult.Ok]);
+            countMeh = Convert.ToInt32(Score.Statistics[HitResult.Meh]);
+            countMiss = Convert.ToInt32(Score.Statistics[HitResult.Miss]);
+
+            if (mods.Any(m => !m.Ranked))
+                return 0;
+
+            IEnumerable<Mod> scoreIncreaseMods = Ruleset.GetModsFor(ModType.DifficultyIncrease);
+
+            double scoreMultiplier = 1.0;
+            foreach (var m in mods.Where(m => !scoreIncreaseMods.Contains(m)))
+                scoreMultiplier *= m.ScoreMultiplier;
+
+            // Scale score up, so it's comparable to other keymods
+            scaledScore *= 1.0 / scoreMultiplier;
+
+            // Arbitrary initial value for scaling pp in order to standardize distributions across game modes.
+            // The specific number has no intrinsic meaning and can be adjusted as needed.
+            double multiplier = 0.8;
+
+            if (mods.Any(m => m is ModNoFail))
+                multiplier *= 0.9;
+            if (mods.Any(m => m is ModEasy))
+                multiplier *= 0.5;
+
+            double strainValue = computeStrainValue();
+            double accValue = computeAccuracyValue(strainValue);
+            double totalValue =
+                Math.Pow(
+                    Math.Pow(strainValue, 1.1) +
+                    Math.Pow(accValue, 1.1), 1.0 / 1.1
+                ) * multiplier;
+
+            if (categoryDifficulty != null)
+            {
+                categoryDifficulty["Strain"] = strainValue;
+                categoryDifficulty["Accuracy"] = accValue;
+            }
+
+            return totalValue;
+        }
+
+        private double computeStrainValue()
+        {
+            // Obtain strain difficulty
+            double strainValue = Math.Pow(5 * Math.Max(1, Attributes["Strain"] / 0.2) - 4.0, 2.2) / 135.0;
+
+            // Longer maps are worth more
+            strainValue *= 1.0 + 0.1 * Math.Min(1.0, totalHits / 1500.0);
+
+            if (scaledScore <= 500000)
+                strainValue = 0;
+            else if (scaledScore <= 600000)
+                strainValue *= (scaledScore - 500000) / 100000 * 0.3;
+            else if (scaledScore <= 700000)
+                strainValue *= 0.3 + (scaledScore - 600000) / 100000 * 0.25;
+            else if (scaledScore <= 800000)
+                strainValue *= 0.55 + (scaledScore - 700000) / 100000 * 0.20;
+            else if (scaledScore <= 900000)
+                strainValue *= 0.75 + (scaledScore - 800000) / 100000 * 0.15;
+            else
+                strainValue *= 0.90 + (scaledScore - 900000) / 100000 * 0.1;
+
+            return strainValue;
+        }
+
+        private double computeAccuracyValue(double strainValue)
+        {
+            double hitWindowGreat = (Beatmap.HitObjects.First().HitWindows.Great / 2 - 0.5) / TimeRate;
+            if (hitWindowGreat <= 0)
+                return 0;
+
+            // Lots of arbitrary values from testing.
+            // Considering to use derivation from perfect accuracy in a probabilistic manner - assume normal distribution
+            double accuracyValue = Math.Max(0.0, 0.2 - (hitWindowGreat - 34) * 0.006667)
+                                       * strainValue
+                                       * Math.Pow(Math.Max(0.0, scaledScore - 960000) / 40000, 1.1);
+
+            // Bonus for many hitcircles - it's harder to keep good accuracy up for longer
+            // accuracyValue *= Math.Min(1.15, Math.Pow(totalHits / 1500.0, 0.3));
+
+            return accuracyValue;
+        }
+
+        private double totalHits => countPerfect + countOk + countGreat + countGood + countMeh + countMiss;
+    }
+}

osu.Game.Rulesets.Mania/ManiaRuleset.cs

@@ -18,6 +18,7 @@ using osu.Game.Beatmaps.Legacy;
 using osu.Game.Rulesets.Difficulty;
 using osu.Game.Rulesets.Mania.Beatmaps;
 using osu.Game.Rulesets.Mania.Difficulty;
+using osu.Game.Rulesets.Scoring;
 
 namespace osu.Game.Rulesets.Mania
 {
@@ -25,6 +26,7 @@ namespace osu.Game.Rulesets.Mania
     {
         public override RulesetContainer CreateRulesetContainerWith(WorkingBeatmap beatmap) => new ManiaRulesetContainer(this, beatmap);
         public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new ManiaBeatmapConverter(beatmap);
+        public override PerformanceCalculator CreatePerformanceCalculator(IBeatmap beatmap, Score score) => new ManiaPerformanceCalculator(this, beatmap, score);
 
         public override IEnumerable<Mod> ConvertLegacyMods(LegacyMods mods)
         {

osu.Game/Rulesets/Difficulty/PerformanceCalculator.cs

@@ -16,6 +16,7 @@ namespace osu.Game.Rulesets.Difficulty
         private readonly Dictionary<string, double> attributes = new Dictionary<string, double>();
         protected IDictionary<string, double> Attributes => attributes;
 
+        protected readonly Ruleset Ruleset;
         protected readonly IBeatmap Beatmap;
         protected readonly Score Score;
 
@@ -23,9 +24,9 @@ namespace osu.Game.Rulesets.Difficulty
 
         protected PerformanceCalculator(Ruleset ruleset, IBeatmap beatmap, Score score)
         {
-            Score = score;
-
+            Ruleset = ruleset;
             Beatmap = beatmap;
+            Score = score;
 
             var diffCalc = ruleset.CreateDifficultyCalculator(beatmap, score.Mods);
             diffCalc.Calculate(attributes);