osu/osu.Game/Rulesets/Difficulty/DifficultyCalculator.cs

188 lines
8.1 KiB
C#

// 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.Framework.Audio.Track;
using osu.Framework.Extensions.IEnumerableExtensions;
using osu.Game.Beatmaps;
using osu.Game.Rulesets.Difficulty.Preprocessing;
using osu.Game.Rulesets.Difficulty.Skills;
using osu.Game.Rulesets.Mods;
using osu.Game.Rulesets.Objects;
namespace osu.Game.Rulesets.Difficulty
{
public abstract class DifficultyCalculator
{
private readonly Ruleset ruleset;
private readonly WorkingBeatmap beatmap;
protected DifficultyCalculator(Ruleset ruleset, WorkingBeatmap beatmap)
{
this.ruleset = ruleset;
this.beatmap = beatmap;
}
/// <summary>
/// Calculates the difficulty of the beatmap using a specific mod combination.
/// </summary>
/// <param name="mods">The mods that should be applied to the beatmap.</param>
/// <returns>A structure describing the difficulty of the beatmap.</returns>
public DifficultyAttributes Calculate(params Mod[] mods)
{
mods = mods.Select(m => m.CreateCopy()).ToArray();
IBeatmap playableBeatmap = beatmap.GetPlayableBeatmap(ruleset.RulesetInfo, mods);
var track = new TrackVirtual(10000);
mods.OfType<IApplicableToTrack>().ForEach(m => m.ApplyToTrack(track));
return calculate(playableBeatmap, mods, track.Rate);
}
/// <summary>
/// Calculates the difficulty of the beatmap using all mod combinations applicable to the beatmap.
/// </summary>
/// <returns>A collection of structures describing the difficulty of the beatmap for each mod combination.</returns>
public IEnumerable<DifficultyAttributes> CalculateAll()
{
foreach (var combination in CreateDifficultyAdjustmentModCombinations())
{
if (combination is MultiMod multi)
yield return Calculate(multi.Mods);
else
yield return Calculate(combination);
}
}
private DifficultyAttributes calculate(IBeatmap beatmap, Mod[] mods, double clockRate)
{
var skills = CreateSkills(beatmap, mods, clockRate);
if (!beatmap.HitObjects.Any())
return CreateDifficultyAttributes(beatmap, mods, skills, clockRate);
var difficultyHitObjects = SortObjects(CreateDifficultyHitObjects(beatmap, clockRate)).ToList();
foreach (var hitObject in difficultyHitObjects)
{
foreach (var skill in skills)
{
skill.ProcessInternal(hitObject);
}
}
return CreateDifficultyAttributes(beatmap, mods, skills, clockRate);
}
/// <summary>
/// Sorts a given set of <see cref="DifficultyHitObject"/>s.
/// </summary>
/// <param name="input">The <see cref="DifficultyHitObject"/>s to sort.</param>
/// <returns>The sorted <see cref="DifficultyHitObject"/>s.</returns>
protected virtual IEnumerable<DifficultyHitObject> SortObjects(IEnumerable<DifficultyHitObject> input)
=> input.OrderBy(h => h.BaseObject.StartTime);
/// <summary>
/// Creates all <see cref="Mod"/> combinations which adjust the <see cref="Beatmap"/> difficulty.
/// </summary>
public Mod[] CreateDifficultyAdjustmentModCombinations()
{
return createDifficultyAdjustmentModCombinations(DifficultyAdjustmentMods, Array.Empty<Mod>()).ToArray();
static IEnumerable<Mod> createDifficultyAdjustmentModCombinations(ReadOnlyMemory<Mod> remainingMods, IEnumerable<Mod> currentSet, int currentSetCount = 0)
{
// Return the current set.
switch (currentSetCount)
{
case 0:
// Initial-case: Empty current set
yield return new ModNoMod();
break;
case 1:
yield return currentSet.Single();
break;
default:
yield return new MultiMod(currentSet.ToArray());
break;
}
// Apply the rest of the remaining mods recursively.
for (int i = 0; i < remainingMods.Length; i++)
{
var (nextSet, nextCount) = flatten(remainingMods.Span[i]);
// Check if any mods in the next set are incompatible with any of the current set.
if (currentSet.SelectMany(m => m.IncompatibleMods).Any(c => nextSet.Any(c.IsInstanceOfType)))
continue;
// Check if any mods in the next set are the same type as the current set. Mods of the exact same type are not incompatible with themselves.
if (currentSet.Any(c => nextSet.Any(n => c.GetType() == n.GetType())))
continue;
// If all's good, attach the next set to the current set and recurse further.
foreach (var combo in createDifficultyAdjustmentModCombinations(remainingMods.Slice(i + 1), currentSet.Concat(nextSet), currentSetCount + nextCount))
yield return combo;
}
}
// Flattens a mod hierarchy (through MultiMod) as an IEnumerable<Mod>
static (IEnumerable<Mod> set, int count) flatten(Mod mod)
{
if (!(mod is MultiMod multi))
return (mod.Yield(), 1);
IEnumerable<Mod> set = Enumerable.Empty<Mod>();
int count = 0;
foreach (var nested in multi.Mods)
{
var (nestedSet, nestedCount) = flatten(nested);
set = set.Concat(nestedSet);
count += nestedCount;
}
return (set, count);
}
}
/// <summary>
/// Retrieves all <see cref="Mod"/>s which adjust the <see cref="Beatmap"/> difficulty.
/// </summary>
protected virtual Mod[] DifficultyAdjustmentMods => Array.Empty<Mod>();
/// <summary>
/// Creates <see cref="DifficultyAttributes"/> to describe beatmap's calculated difficulty.
/// </summary>
/// <param name="beatmap">The <see cref="IBeatmap"/> whose difficulty was calculated.</param>
/// <param name="mods">The <see cref="Mod"/>s that difficulty was calculated with.</param>
/// <param name="skills">The skills which processed the beatmap.</param>
/// <param name="clockRate">The rate at which the gameplay clock is run at.</param>
protected abstract DifficultyAttributes CreateDifficultyAttributes(IBeatmap beatmap, Mod[] mods, Skill[] skills, double clockRate);
/// <summary>
/// Enumerates <see cref="DifficultyHitObject"/>s to be processed from <see cref="HitObject"/>s in the <see cref="IBeatmap"/>.
/// </summary>
/// <param name="beatmap">The <see cref="IBeatmap"/> providing the <see cref="HitObject"/>s to enumerate.</param>
/// <param name="clockRate">The rate at which the gameplay clock is run at.</param>
/// <returns>The enumerated <see cref="DifficultyHitObject"/>s.</returns>
protected abstract IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate);
/// <summary>
/// Creates the <see cref="Skill"/>s to calculate the difficulty of an <see cref="IBeatmap"/>.
/// </summary>
/// <param name="beatmap">The <see cref="IBeatmap"/> whose difficulty will be calculated.</param>
/// <param name="mods">Mods to calculate difficulty with.</param>
/// <param name="clockRate">Clockrate to calculate difficulty with.</param>
/// <returns>The <see cref="Skill"/>s.</returns>
protected abstract Skill[] CreateSkills(IBeatmap beatmap, Mod[] mods, double clockRate);
}
}