Merge pull request #4279 from smoogipoo/new-diffcalc-catch

Migrate catch to use the new difficulty calculator structure

osu.Game.Rulesets.Catch.Tests/CatchDifficultyCalculatorTest.cs

@@ -13,11 +13,11 @@ namespace osu.Game.Rulesets.Catch.Tests
     {
         protected override string ResourceAssembly => "osu.Game.Rulesets.Catch";
 
-        [TestCase(3.8664391043534758, "diffcalc-test")]
+        [TestCase(3.8701854263563118d, "diffcalc-test")]
         public void Test(double expected, string name)
             => base.Test(expected, name);
 
-        protected override LegacyDifficultyCalculator CreateDifficultyCalculator(WorkingBeatmap beatmap) => new CatchLegacyDifficultyCalculator(new CatchRuleset(), beatmap);
+        protected override LegacyDifficultyCalculator CreateDifficultyCalculator(WorkingBeatmap beatmap) => new CatchDifficultyCalculator(new CatchRuleset(), beatmap);
 
         protected override Ruleset CreateRuleset() => new CatchRuleset();
     }

osu.Game.Rulesets.Catch/CatchRuleset.cs

@@ -110,7 +110,7 @@ namespace osu.Game.Rulesets.Catch
 
         public override Drawable CreateIcon() => new SpriteIcon { Icon = FontAwesome.fa_osu_fruits_o };
 
-        public override LegacyDifficultyCalculator CreateDifficultyCalculator(WorkingBeatmap beatmap) => new CatchLegacyDifficultyCalculator(this, beatmap);
+        public override LegacyDifficultyCalculator CreateDifficultyCalculator(WorkingBeatmap beatmap) => new CatchDifficultyCalculator(this, beatmap);
 
         public override int? LegacyID => 2;
 

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

@@ -2,7 +2,6 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Game.Rulesets.Difficulty;
-using osu.Game.Rulesets.Mods;
 
 namespace osu.Game.Rulesets.Catch.Difficulty
 {
@@ -10,10 +9,5 @@ namespace osu.Game.Rulesets.Catch.Difficulty
     {
         public double ApproachRate;
         public int MaxCombo;
-
-        public CatchDifficultyAttributes(Mod[] mods, double starRating)
-            : base(mods, starRating)
-        {
-        }
     }
 }

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

@@ -0,0 +1,86 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets.Catch.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Catch.Difficulty.Skills;
+using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.Catch.UI;
+using osu.Game.Rulesets.Difficulty;
+using osu.Game.Rulesets.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Difficulty.Skills;
+using osu.Game.Rulesets.Mods;
+
+namespace osu.Game.Rulesets.Catch.Difficulty
+{
+    public class CatchDifficultyCalculator : DifficultyCalculator
+    {
+        private const double star_scaling_factor = 0.145;
+
+        protected override int SectionLength => 750;
+
+        private readonly float halfCatchWidth;
+
+        public CatchDifficultyCalculator(Ruleset ruleset, WorkingBeatmap beatmap)
+            : base(ruleset, beatmap)
+        {
+            var catcher = new CatcherArea.Catcher(beatmap.BeatmapInfo.BaseDifficulty);
+            halfCatchWidth = catcher.CatchWidth * 0.5f;
+        }
+
+        protected override DifficultyAttributes CreateDifficultyAttributes(IBeatmap beatmap, Mod[] mods, Skill[] skills, double clockRate)
+        {
+            if (beatmap.HitObjects.Count == 0)
+                return new CatchDifficultyAttributes { Mods = mods };
+
+            // this is the same as osu!, so there's potential to share the implementation... maybe
+            double preempt = BeatmapDifficulty.DifficultyRange(beatmap.BeatmapInfo.BaseDifficulty.ApproachRate, 1800, 1200, 450) / clockRate;
+
+            return new CatchDifficultyAttributes
+            {
+                StarRating = Math.Sqrt(skills[0].DifficultyValue()) * star_scaling_factor,
+                Mods = mods,
+                ApproachRate = preempt > 1200.0 ? -(preempt - 1800.0) / 120.0 : -(preempt - 1200.0) / 150.0 + 5.0,
+                MaxCombo = beatmap.HitObjects.Count(h => h is Fruit) + beatmap.HitObjects.OfType<JuiceStream>().SelectMany(j => j.NestedHitObjects).Count(h => !(h is TinyDroplet))
+            };
+        }
+
+        protected override IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate)
+        {
+            CatchHitObject lastObject = null;
+
+            foreach (var hitObject in beatmap.HitObjects.OfType<CatchHitObject>())
+            {
+                if (lastObject == null)
+                {
+                    lastObject = hitObject;
+                    continue;
+                }
+
+                switch (hitObject)
+                {
+                    // We want to only consider fruits that contribute to the combo. Droplets are addressed as accuracy and spinners are not relevant for "skill" calculations.
+                    case Fruit fruit:
+                        yield return new CatchDifficultyHitObject(fruit, lastObject, clockRate, halfCatchWidth);
+                        lastObject = hitObject;
+                        break;
+                    case JuiceStream _:
+                        foreach (var nested in hitObject.NestedHitObjects.OfType<CatchHitObject>().Where(o => !(o is TinyDroplet)))
+                        {
+                            yield return new CatchDifficultyHitObject(nested, lastObject, clockRate, halfCatchWidth);
+                            lastObject = nested;
+                        }
+                        break;
+                }
+            }
+        }
+
+        protected override Skill[] CreateSkills(IBeatmap beatmap) => new Skill[]
+        {
+            new Movement(),
+        };
+    }
+}

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

@@ -1,130 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-using System;
-using osu.Game.Rulesets.Catch.Objects;
-using osu.Game.Rulesets.Catch.UI;
-using osuTK;
-
-namespace osu.Game.Rulesets.Catch.Difficulty
-{
-    public class CatchDifficultyHitObject
-    {
-        internal static readonly double DECAY_BASE = 0.20;
-        private const float normalized_hitobject_radius = 41.0f;
-        private const float absolute_player_positioning_error = 16f;
-        private readonly float playerPositioningError;
-
-        internal CatchHitObject BaseHitObject;
-
-        /// <summary>
-        /// Measures jump difficulty. CtB doesn't have something like button pressing speed or accuracy
-        /// </summary>
-        internal double Strain = 1;
-
-        /// <summary>
-        /// This is required to keep track of lazy player movement (always moving only as far as necessary)
-        /// Without this quick repeat sliders / weirdly shaped streams might become ridiculously overrated
-        /// </summary>
-        internal float PlayerPositionOffset;
-        internal float LastMovement;
-
-        internal float NormalizedPosition;
-        internal float ActualNormalizedPosition => NormalizedPosition + PlayerPositionOffset;
-
-        internal CatchDifficultyHitObject(CatchHitObject baseHitObject, float catcherWidthHalf)
-        {
-            BaseHitObject = baseHitObject;
-
-            // We will scale everything by this factor, so we can assume a uniform CircleSize among beatmaps.
-            float scalingFactor = normalized_hitobject_radius / catcherWidthHalf;
-
-            playerPositioningError = absolute_player_positioning_error; // * scalingFactor;
-            NormalizedPosition = baseHitObject.X * CatchPlayfield.BASE_WIDTH * scalingFactor;
-        }
-
-        private const double direction_change_bonus = 12.5;
-        internal void CalculateStrains(CatchDifficultyHitObject previousHitObject, double timeRate)
-        {
-            // Rather simple, but more specialized things are inherently inaccurate due to the big difference playstyles and opinions make.
-            // See Taiko feedback thread.
-            double timeElapsed = (BaseHitObject.StartTime - previousHitObject.BaseHitObject.StartTime) / timeRate;
-            double decay = Math.Pow(DECAY_BASE, timeElapsed / 1000);
-
-            // Update new position with lazy movement.
-            PlayerPositionOffset =
-                MathHelper.Clamp(
-                    previousHitObject.ActualNormalizedPosition,
-                    NormalizedPosition - (normalized_hitobject_radius - playerPositioningError),
-                    NormalizedPosition + (normalized_hitobject_radius - playerPositioningError)) // Obtain new lazy position, but be stricter by allowing for an error of a certain degree of the player.
-                - NormalizedPosition; // Subtract HitObject position to obtain offset
-
-            LastMovement = DistanceTo(previousHitObject);
-            double addition = spacingWeight(LastMovement);
-
-            if (NormalizedPosition < previousHitObject.NormalizedPosition)
-            {
-                LastMovement = -LastMovement;
-            }
-
-            CatchHitObject previousHitCircle = previousHitObject.BaseHitObject;
-
-            double additionBonus = 0;
-            double sqrtTime = Math.Sqrt(Math.Max(timeElapsed, 25));
-
-            // Direction changes give an extra point!
-            if (Math.Abs(LastMovement) > 0.1)
-            {
-                if (Math.Abs(previousHitObject.LastMovement) > 0.1 && Math.Sign(LastMovement) != Math.Sign(previousHitObject.LastMovement))
-                {
-                    double bonus = direction_change_bonus / sqrtTime;
-
-                    // Weight bonus by how
-                    double bonusFactor = Math.Min(playerPositioningError, Math.Abs(LastMovement)) / playerPositioningError;
-
-                    // We want time to play a role twice here!
-                    addition += bonus * bonusFactor;
-
-                    // Bonus for tougher direction switches and "almost" hyperdashes at this point
-                    if (previousHitCircle != null && previousHitCircle.DistanceToHyperDash <= 10.0f / CatchPlayfield.BASE_WIDTH)
-                    {
-                        additionBonus += 0.3 * bonusFactor;
-                    }
-                }
-
-                // Base bonus for every movement, giving some weight to streams.
-                addition += 7.5 * Math.Min(Math.Abs(LastMovement), normalized_hitobject_radius * 2) / (normalized_hitobject_radius * 6) / sqrtTime;
-            }
-
-            // Bonus for "almost" hyperdashes at corner points
-            if (previousHitCircle != null && previousHitCircle.DistanceToHyperDash <= 10.0f / CatchPlayfield.BASE_WIDTH)
-            {
-                if (!previousHitCircle.HyperDash)
-                {
-                    additionBonus += 1.0;
-                }
-                else
-                {
-                    // After a hyperdash we ARE in the correct position. Always!
-                    PlayerPositionOffset = 0;
-                }
-
-                addition *= 1.0 + additionBonus * ((10 - previousHitCircle.DistanceToHyperDash * CatchPlayfield.BASE_WIDTH) / 10);
-            }
-
-            addition *= 850.0 / Math.Max(timeElapsed, 25);
-
-            Strain = previousHitObject.Strain * decay + addition;
-        }
-
-        private static double spacingWeight(float distance)
-        {
-            return Math.Pow(distance, 1.3) / 500;
-        }
-
-        internal float DistanceTo(CatchDifficultyHitObject other)
-        {
-            return Math.Abs(ActualNormalizedPosition - other.ActualNormalizedPosition);
-        }
-    }
-}

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

@@ -1,148 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-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.Catch.Objects;
-using osu.Game.Rulesets.Catch.UI;
-
-namespace osu.Game.Rulesets.Catch.Difficulty
-{
-    public class CatchLegacyDifficultyCalculator : LegacyDifficultyCalculator
-    {
-        /// <summary>
-        /// In milliseconds. For difficulty calculation we will only look at the highest strain value in each time interval of size STRAIN_STEP.
-        /// This is to eliminate higher influence of stream over aim by simply having more HitObjects with high strain.
-        /// The higher this value, the less strains there will be, indirectly giving long beatmaps an advantage.
-        /// </summary>
-        private const double strain_step = 750;
-
-        /// <summary>
-        /// The weighting of each strain value decays to this number * it's previous value
-        /// </summary>
-        private const double decay_weight = 0.94;
-
-        private const double star_scaling_factor = 0.145;
-
-        public CatchLegacyDifficultyCalculator(Ruleset ruleset, WorkingBeatmap beatmap)
-            : base(ruleset, beatmap)
-        {
-        }
-
-        protected override DifficultyAttributes Calculate(IBeatmap beatmap, Mod[] mods, double clockRate)
-        {
-            if (!beatmap.HitObjects.Any())
-                return new CatchDifficultyAttributes(mods, 0);
-
-            var catcher = new CatcherArea.Catcher(beatmap.BeatmapInfo.BaseDifficulty);
-            float halfCatchWidth = catcher.CatchWidth * 0.5f;
-
-            var difficultyHitObjects = new List<CatchDifficultyHitObject>();
-
-            foreach (var hitObject in beatmap.HitObjects)
-            {
-                switch (hitObject)
-                {
-                    // We want to only consider fruits that contribute to the combo. Droplets are addressed as accuracy and spinners are not relevant for "skill" calculations.
-                    case Fruit fruit:
-                        difficultyHitObjects.Add(new CatchDifficultyHitObject(fruit, halfCatchWidth));
-                        break;
-                    case JuiceStream _:
-                        difficultyHitObjects.AddRange(hitObject.NestedHitObjects.OfType<CatchHitObject>().Where(o => !(o is TinyDroplet)).Select(o => new CatchDifficultyHitObject(o, halfCatchWidth)));
-                        break;
-                }
-            }
-
-            difficultyHitObjects.Sort((a, b) => a.BaseHitObject.StartTime.CompareTo(b.BaseHitObject.StartTime));
-
-            if (!calculateStrainValues(difficultyHitObjects, clockRate))
-                return new CatchDifficultyAttributes(mods, 0);
-
-            // this is the same as osu!, so there's potential to share the implementation... maybe
-            double preempt = BeatmapDifficulty.DifficultyRange(beatmap.BeatmapInfo.BaseDifficulty.ApproachRate, 1800, 1200, 450) / clockRate;
-            double starRating = Math.Sqrt(calculateDifficulty(difficultyHitObjects, clockRate)) * star_scaling_factor;
-
-            return new CatchDifficultyAttributes(mods, starRating)
-            {
-                ApproachRate = preempt > 1200.0 ? -(preempt - 1800.0) / 120.0 : -(preempt - 1200.0) / 150.0 + 5.0,
-                MaxCombo = difficultyHitObjects.Count
-            };
-        }
-
-        private bool calculateStrainValues(List<CatchDifficultyHitObject> objects, double timeRate)
-        {
-            CatchDifficultyHitObject lastObject = null;
-
-            if (!objects.Any()) return false;
-
-            // Traverse hitObjects in pairs to calculate the strain value of NextHitObject from the strain value of CurrentHitObject and environment.
-            foreach (var currentObject in objects)
-            {
-                if (lastObject != null)
-                    currentObject.CalculateStrains(lastObject, timeRate);
-
-                lastObject = currentObject;
-            }
-
-            return true;
-        }
-
-        private double calculateDifficulty(List<CatchDifficultyHitObject> objects, double timeRate)
-        {
-            // The strain step needs to be adjusted for the algorithm to be considered equal with speed changing mods
-            double actualStrainStep = strain_step * timeRate;
-
-            // Find the highest strain value within each strain step
-            var highestStrains = new List<double>();
-            double intervalEndTime = actualStrainStep;
-            double maximumStrain = 0; // We need to keep track of the maximum strain in the current interval
-
-            CatchDifficultyHitObject previousHitObject = null;
-            foreach (CatchDifficultyHitObject hitObject in objects)
-            {
-                // While we are beyond the current interval push the currently available maximum to our strain list
-                while (hitObject.BaseHitObject.StartTime > intervalEndTime)
-                {
-                    highestStrains.Add(maximumStrain);
-
-                    // The maximum strain of the next interval is not zero by default! We need to take the last hitObject we encountered, take its strain and apply the decay
-                    // until the beginning of the next interval.
-                    if (previousHitObject == null)
-                    {
-                        maximumStrain = 0;
-                    }
-                    else
-                    {
-                        double decay = Math.Pow(CatchDifficultyHitObject.DECAY_BASE, (intervalEndTime - previousHitObject.BaseHitObject.StartTime) / 1000);
-                        maximumStrain = previousHitObject.Strain * decay;
-                    }
-
-                    // Go to the next time interval
-                    intervalEndTime += actualStrainStep;
-                }
-
-                // Obtain maximum strain
-                maximumStrain = Math.Max(hitObject.Strain, maximumStrain);
-
-                previousHitObject = hitObject;
-            }
-
-            // Build the weighted sum over the highest strains for each interval
-            double difficulty = 0;
-            double weight = 1;
-            highestStrains.Sort((a, b) => b.CompareTo(a)); // Sort from highest to lowest strain.
-
-            foreach (double strain in highestStrains)
-            {
-                difficulty += weight * strain;
-                weight *= decay_weight;
-            }
-
-            return difficulty;
-        }
-    }
-}

osu.Game.Rulesets.Catch/Difficulty/Preprocessing/CatchDifficultyHitObject.cs

@@ -0,0 +1,39 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.Catch.UI;
+using osu.Game.Rulesets.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Objects;
+
+namespace osu.Game.Rulesets.Catch.Difficulty.Preprocessing
+{
+    public class CatchDifficultyHitObject : DifficultyHitObject
+    {
+        private const float normalized_hitobject_radius = 41.0f;
+
+        public new CatchHitObject BaseObject => (CatchHitObject)base.BaseObject;
+
+        public new CatchHitObject LastObject => (CatchHitObject)base.LastObject;
+
+        public readonly float NormalizedPosition;
+
+        /// <summary>
+        /// Milliseconds elapsed since the start time of the previous <see cref="CatchDifficultyHitObject"/>, with a minimum of 25ms.
+        /// </summary>
+        public readonly double StrainTime;
+
+        public CatchDifficultyHitObject(HitObject hitObject, HitObject lastObject, double clockRate, float halfCatcherWidth)
+            : base(hitObject, lastObject, clockRate)
+        {
+            // We will scale everything by this factor, so we can assume a uniform CircleSize among beatmaps.
+            var scalingFactor = normalized_hitobject_radius / halfCatcherWidth;
+
+            NormalizedPosition = BaseObject.X * CatchPlayfield.BASE_WIDTH * scalingFactor;
+
+            // Every strain interval is hard capped at the equivalent of 600 BPM streaming speed as a safety measure
+            StrainTime = Math.Max(25, DeltaTime);
+        }
+    }
+}

osu.Game.Rulesets.Catch/Difficulty/Skills/Movement.cs

@@ -0,0 +1,82 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Game.Rulesets.Catch.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Catch.UI;
+using osu.Game.Rulesets.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Difficulty.Skills;
+using osuTK;
+
+namespace osu.Game.Rulesets.Catch.Difficulty.Skills
+{
+    public class Movement : Skill
+    {
+        private const float absolute_player_positioning_error = 16f;
+        private const float normalized_hitobject_radius = 41.0f;
+        private const double direction_change_bonus = 12.5;
+
+        protected override double SkillMultiplier => 850;
+        protected override double StrainDecayBase => 0.2;
+
+        protected override double DecayWeight => 0.94;
+
+        private float lastPlayerPosition;
+        private float lastDistanceMoved;
+
+        protected override double StrainValueOf(DifficultyHitObject current)
+        {
+            var catchCurrent = (CatchDifficultyHitObject)current;
+
+            float playerPosition = MathHelper.Clamp(
+                lastPlayerPosition,
+                catchCurrent.NormalizedPosition - (normalized_hitobject_radius - absolute_player_positioning_error),
+                catchCurrent.NormalizedPosition + (normalized_hitobject_radius - absolute_player_positioning_error)
+            );
+
+            float distanceMoved = playerPosition - lastPlayerPosition;
+
+            double distanceAddition = Math.Pow(Math.Abs(distanceMoved), 1.3) / 500;
+            double sqrtStrain = Math.Sqrt(catchCurrent.StrainTime);
+
+            double bonus = 0;
+
+            // Direction changes give an extra point!
+            if (Math.Abs(distanceMoved) > 0.1)
+            {
+                if (Math.Abs(lastDistanceMoved) > 0.1 && Math.Sign(distanceMoved) != Math.Sign(lastDistanceMoved))
+                {
+                    double bonusFactor = Math.Min(absolute_player_positioning_error, Math.Abs(distanceMoved)) / absolute_player_positioning_error;
+
+                    distanceAddition += direction_change_bonus / sqrtStrain * bonusFactor;
+
+                    // Bonus for tougher direction switches and "almost" hyperdashes at this point
+                    if (catchCurrent.LastObject.DistanceToHyperDash <= 10 / CatchPlayfield.BASE_WIDTH)
+                        bonus = 0.3 * bonusFactor;
+                }
+
+                // Base bonus for every movement, giving some weight to streams.
+                distanceAddition += 7.5 * Math.Min(Math.Abs(distanceMoved), normalized_hitobject_radius * 2) / (normalized_hitobject_radius * 6) / sqrtStrain;
+            }
+
+            // Bonus for "almost" hyperdashes at corner points
+            if (catchCurrent.LastObject.DistanceToHyperDash <= 10.0f / CatchPlayfield.BASE_WIDTH)
+            {
+                if (!catchCurrent.LastObject.HyperDash)
+                    bonus += 1.0;
+                else
+                {
+                    // After a hyperdash we ARE in the correct position. Always!
+                    playerPosition = catchCurrent.NormalizedPosition;
+                }
+
+                distanceAddition *= 1.0 + bonus * ((10 - catchCurrent.LastObject.DistanceToHyperDash * CatchPlayfield.BASE_WIDTH) / 10);
+            }
+
+            lastPlayerPosition = playerPosition;
+            lastDistanceMoved = distanceMoved;
+
+            return distanceAddition / catchCurrent.StrainTime;
+        }
+    }
+}