Attempt to implement Catch performance calculator

osu.Game.Rulesets.Catch/CatchRuleset.cs

@@ -16,6 +16,7 @@ using osu.Game.Beatmaps.Legacy;
 using osu.Game.Rulesets.Catch.Beatmaps;
 using osu.Game.Rulesets.Catch.Difficulty;
 using osu.Game.Rulesets.Difficulty;
+using osu.Game.Scoring;
 
 namespace osu.Game.Rulesets.Catch
 {
@@ -112,6 +113,8 @@ namespace osu.Game.Rulesets.Catch
 
         public override DifficultyCalculator CreateDifficultyCalculator(WorkingBeatmap beatmap) => new CatchDifficultyCalculator(this, beatmap);
 
+        public override PerformanceCalculator CreatePerformanceCalculator(WorkingBeatmap beatmap, ScoreInfo score) => new CatchPerformanceCalculator(this, beatmap, score);
+
         public override int? LegacyID => 2;
 
         public override IConvertibleReplayFrame CreateConvertibleReplayFrame() => new CatchReplayFrame();

osu.Game.Rulesets.Catch/Difficulty/CatchPerformanceCalculator.cs

@@ -0,0 +1,98 @@
+// Copyright (c) 2007-2019 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;
+using osu.Game.Scoring;
+using osuTK;
+
+namespace osu.Game.Rulesets.Catch.Difficulty
+{
+    public class CatchPerformanceCalculator : PerformanceCalculator
+    {
+        protected new CatchDifficultyAttributes Attributes => (CatchDifficultyAttributes)base.Attributes;
+
+        private Mod[] mods;
+        private int countGreat;
+        private int countGood;
+        private int countMeh;
+        private int countMiss;
+        private int countKatu;
+
+        public CatchPerformanceCalculator(Ruleset ruleset, WorkingBeatmap beatmap, ScoreInfo score)
+            : base(ruleset, beatmap, score) { }
+
+        public override double Calculate(Dictionary<string, double> categoryDifficulty = null)
+        {
+            mods = Score.Mods;
+            countGreat = Convert.ToInt32(Score.Statistics[HitResult.Great]);
+            countGood = Convert.ToInt32(Score.Statistics[HitResult.Good]);
+            countMeh = Convert.ToInt32(Score.Statistics[HitResult.Meh]);
+            countMiss = Convert.ToInt32(Score.Statistics[HitResult.Miss]);
+            countKatu = Convert.ToInt32(Score.Statistics[HitResult.Ok]);    // TODO: check
+
+            // Don't count scores made with supposedly unranked mods
+            if (mods.Any(m => !m.Ranked))
+                return 0;
+
+            // We are heavily relying on aim in catch the beat
+            // TODO: replaced Aim with StarRating, not sure if this is correct!
+            double value = Math.Pow(5.0f * Math.Max(1.0f, Attributes.StarRating / 0.0049f) - 4.0f, 2.0f) / 100000.0f;
+
+            // Longer maps are worth more. "Longer" means how many hits there are which can contribute to combo
+            int numTotalHits = totalComboHits();
+
+            // Longer maps are worth more
+            float lengthBonus =
+                0.95f + 0.4f * Math.Min(1.0f, numTotalHits / 3000.0f) +
+                (numTotalHits > 3000 ? (float)Math.Log10(numTotalHits / 3000.0f) * 0.5f : 0.0f);
+
+            // Longer maps are worth more
+            value *= lengthBonus;
+
+            // Penalize misses exponentially. This mainly fixes tag4 maps and the likes until a per-hitobject solution is available
+            value *= Math.Pow(0.97f, countMiss);
+
+            // Combo scaling
+            float beatmapMaxCombo = Attributes.MaxCombo;
+            if (beatmapMaxCombo > 0)
+                value *= Math.Min(Math.Pow(Attributes.MaxCombo, 0.8f) / Math.Pow(beatmapMaxCombo, 0.8f), 1.0f);
+
+            float approachRate = (float)Attributes.ApproachRate;
+            float approachRateFactor = 1.0f;
+            if (approachRate > 9.0f)
+                approachRateFactor += 0.1f * (approachRate - 9.0f); // 10% for each AR above 9
+            else if (approachRate < 8.0f)
+                approachRateFactor += 0.025f * (8.0f - approachRate); // 2.5% for each AR below 8
+
+            value *= approachRateFactor;
+
+            if (mods.Any(m => m is ModHidden))
+                // Hiddens gives nothing on max approach rate, and more the lower it is
+                value *= 1.05f + 0.075f * (10.0f - Math.Min(10.0f, approachRate)); // 7.5% for each AR below 10
+
+            if (mods.Any(m => m is ModFlashlight))
+                // Apply length bonus again if flashlight is on simply because it becomes a lot harder on longer maps.
+                value *= 1.35f * lengthBonus;
+
+            // Scale the aim value with accuracy _slightly_
+            value *= Math.Pow(accuracy(), 5.5f);
+
+            // Custom multipliers for NoFail. SpunOut is not applicable.
+            if (mods.Any(m => m is ModNoFail))
+                value *= 0.90f;
+
+            return value;
+        }
+
+        private float accuracy() => totalHits() == 0 ? 0 : MathHelper.Clamp((float)totalSuccessfulHits() / totalHits(), 0f, 1f);
+        private int totalHits() => countMeh + countGood + countGreat + countMiss + countKatu;
+        private int totalSuccessfulHits() => countMeh + countGood + countGreat;
+        private int totalComboHits() => countMeh + countGood + countGreat;
+    }
+}