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175 lines
7.4 KiB
C#
175 lines
7.4 KiB
C#
// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
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// See the LICENCE file in the repository root for full licence text.
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using osu.Framework.Audio.Track;
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using osu.Framework.Extensions.IEnumerableExtensions;
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using osu.Game.Beatmaps;
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using osu.Game.Rulesets.Difficulty.Preprocessing;
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using osu.Game.Rulesets.Difficulty.Skills;
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using osu.Game.Rulesets.Mods;
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using osu.Game.Rulesets.Objects;
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namespace osu.Game.Rulesets.Difficulty
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{
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public abstract class DifficultyCalculator
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{
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/// <summary>
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/// The length of each strain section.
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/// </summary>
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protected virtual int SectionLength => 400;
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private readonly Ruleset ruleset;
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private readonly WorkingBeatmap beatmap;
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protected DifficultyCalculator(Ruleset ruleset, WorkingBeatmap beatmap)
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{
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this.ruleset = ruleset;
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this.beatmap = beatmap;
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}
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/// <summary>
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/// Calculates the difficulty of the beatmap using a specific mod combination.
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/// </summary>
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/// <param name="mods">The mods that should be applied to the beatmap.</param>
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/// <returns>A structure describing the difficulty of the beatmap.</returns>
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public DifficultyAttributes Calculate(params Mod[] mods)
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{
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mods = mods.Select(m => m.CreateCopy()).ToArray();
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IBeatmap playableBeatmap = beatmap.GetPlayableBeatmap(ruleset.RulesetInfo, mods);
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var track = new TrackVirtual(10000);
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mods.OfType<IApplicableToTrack>().ForEach(m => m.ApplyToTrack(track));
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return calculate(playableBeatmap, mods, track.Rate);
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}
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/// <summary>
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/// Calculates the difficulty of the beatmap using all mod combinations applicable to the beatmap.
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/// </summary>
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/// <returns>A collection of structures describing the difficulty of the beatmap for each mod combination.</returns>
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public IEnumerable<DifficultyAttributes> CalculateAll()
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{
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foreach (var combination in CreateDifficultyAdjustmentModCombinations())
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{
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if (combination is MultiMod multi)
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yield return Calculate(multi.Mods);
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else
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yield return Calculate(combination);
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}
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}
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private DifficultyAttributes calculate(IBeatmap beatmap, Mod[] mods, double clockRate)
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{
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var skills = CreateSkills(beatmap);
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if (!beatmap.HitObjects.Any())
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return CreateDifficultyAttributes(beatmap, mods, skills, clockRate);
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var difficultyHitObjects = CreateDifficultyHitObjects(beatmap, clockRate).OrderBy(h => h.BaseObject.StartTime).ToList();
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double sectionLength = SectionLength * clockRate;
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// The first object doesn't generate a strain, so we begin with an incremented section end
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double currentSectionEnd = Math.Ceiling(beatmap.HitObjects.First().StartTime / sectionLength) * sectionLength;
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foreach (DifficultyHitObject h in difficultyHitObjects)
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{
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while (h.BaseObject.StartTime > currentSectionEnd)
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{
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foreach (Skill s in skills)
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{
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s.SaveCurrentPeak();
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s.StartNewSectionFrom(currentSectionEnd);
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}
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currentSectionEnd += sectionLength;
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}
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foreach (Skill s in skills)
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s.Process(h);
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}
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// The peak strain will not be saved for the last section in the above loop
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foreach (Skill s in skills)
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s.SaveCurrentPeak();
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return CreateDifficultyAttributes(beatmap, mods, skills, clockRate);
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}
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/// <summary>
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/// Creates all <see cref="Mod"/> combinations which adjust the <see cref="Beatmap"/> difficulty.
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/// </summary>
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public Mod[] CreateDifficultyAdjustmentModCombinations()
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{
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return createDifficultyAdjustmentModCombinations(Array.Empty<Mod>(), DifficultyAdjustmentMods).ToArray();
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IEnumerable<Mod> createDifficultyAdjustmentModCombinations(IEnumerable<Mod> currentSet, Mod[] adjustmentSet, int currentSetCount = 0, int adjustmentSetStart = 0)
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{
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switch (currentSetCount)
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{
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case 0:
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// Initial-case: Empty current set
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yield return new ModNoMod();
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break;
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case 1:
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yield return currentSet.Single();
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break;
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default:
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yield return new MultiMod(currentSet.ToArray());
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break;
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}
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// Apply mods in the adjustment set recursively. Using the entire adjustment set would result in duplicate multi-mod mod
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// combinations in further recursions, so a moving subset is used to eliminate this effect
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for (int i = adjustmentSetStart; i < adjustmentSet.Length; i++)
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{
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var adjustmentMod = adjustmentSet[i];
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if (currentSet.Any(c => c.IncompatibleMods.Any(m => m.IsInstanceOfType(adjustmentMod))))
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continue;
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foreach (var combo in createDifficultyAdjustmentModCombinations(currentSet.Append(adjustmentMod), adjustmentSet, currentSetCount + 1, i + 1))
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yield return combo;
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}
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}
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}
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/// <summary>
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/// Retrieves all <see cref="Mod"/>s which adjust the <see cref="Beatmap"/> difficulty.
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/// </summary>
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protected virtual Mod[] DifficultyAdjustmentMods => Array.Empty<Mod>();
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/// <summary>
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/// Creates <see cref="DifficultyAttributes"/> to describe beatmap's calculated difficulty.
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/// </summary>
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/// <param name="beatmap">The <see cref="IBeatmap"/> whose difficulty was calculated.</param>
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/// <param name="mods">The <see cref="Mod"/>s that difficulty was calculated with.</param>
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/// <param name="skills">The skills which processed the beatmap.</param>
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/// <param name="clockRate">The rate at which the gameplay clock is run at.</param>
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protected abstract DifficultyAttributes CreateDifficultyAttributes(IBeatmap beatmap, Mod[] mods, Skill[] skills, double clockRate);
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/// <summary>
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/// Enumerates <see cref="DifficultyHitObject"/>s to be processed from <see cref="HitObject"/>s in the <see cref="IBeatmap"/>.
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/// </summary>
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/// <param name="beatmap">The <see cref="IBeatmap"/> providing the <see cref="HitObject"/>s to enumerate.</param>
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/// <param name="clockRate">The rate at which the gameplay clock is run at.</param>
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/// <returns>The enumerated <see cref="DifficultyHitObject"/>s.</returns>
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protected abstract IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate);
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/// <summary>
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/// Creates the <see cref="Skill"/>s to calculate the difficulty of an <see cref="IBeatmap"/>.
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/// </summary>
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/// <param name="beatmap">The <see cref="IBeatmap"/> whose difficulty will be calculated.</param>
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/// <returns>The <see cref="Skill"/>s.</returns>
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protected abstract Skill[] CreateSkills(IBeatmap beatmap);
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}
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}
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