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osu-lazer/osu.Game.Rulesets.Taiko/Difficulty/Skills/Peaks.cs
2022-07-15 21:07:01 +10:00

96 lines
3.7 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.
#nullable disable
using System;
using System.Collections.Generic;
using System.Linq;
using osu.Game.Rulesets.Difficulty.Preprocessing;
using osu.Game.Rulesets.Difficulty.Skills;
using osu.Game.Rulesets.Mods;
namespace osu.Game.Rulesets.Taiko.Difficulty.Skills
{
public class Peaks : Skill
{
private const double rhythm_skill_multiplier = 0.2 * final_multiplier;
private const double colour_skill_multiplier = 0.375 * final_multiplier;
private const double stamina_skill_multiplier = 0.375 * final_multiplier;
private const double final_multiplier = 0.0625;
private readonly Rhythm rhythm;
private readonly Colour colour;
private readonly Stamina stamina;
public double ColourDifficultyValue => colour.DifficultyValue() * colour_skill_multiplier;
public double RhythmDifficultyValue => rhythm.DifficultyValue() * rhythm_skill_multiplier;
public double StaminaDifficultyValue => stamina.DifficultyValue() * stamina_skill_multiplier;
public Peaks(Mod[] mods)
: base(mods)
{
rhythm = new Rhythm(mods);
colour = new Colour(mods);
stamina = new Stamina(mods);
}
/// <summary>
/// Returns the <i>p</i>-norm of an <i>n</i>-dimensional vector.
/// </summary>
/// <param name="p">The value of <i>p</i> to calculate the norm for.</param>
/// <param name="values">The coefficients of the vector.</param>
private double norm(double p, params double[] values) => Math.Pow(values.Sum(x => Math.Pow(x, p)), 1 / p);
public override void Process(DifficultyHitObject current)
{
rhythm.Process(current);
colour.Process(current);
stamina.Process(current);
}
/// <summary>
/// Returns the combined star rating of the beatmap, calculated using peak strains from all sections of the map.
/// </summary>
/// <remarks>
/// For each section, the peak strains of all separate skills are combined into a single peak strain for the section.
/// The resulting partial rating of the beatmap is a weighted sum of the combined peaks (higher peaks are weighted more).
/// </remarks>
public override double DifficultyValue()
{
List<double> peaks = new List<double>();
var colourPeaks = colour.GetCurrentStrainPeaks().ToList();
var rhythmPeaks = rhythm.GetCurrentStrainPeaks().ToList();
var staminaPeaks = stamina.GetCurrentStrainPeaks().ToList();
for (int i = 0; i < colourPeaks.Count; i++)
{
double colourPeak = colourPeaks[i] * colour_skill_multiplier;
double rhythmPeak = rhythmPeaks[i] * rhythm_skill_multiplier;
double staminaPeak = staminaPeaks[i] * stamina_skill_multiplier;
double peak = norm(1.5, colourPeak, staminaPeak);
peak = norm(2, peak, rhythmPeak);
// Sections with 0 strain are excluded to avoid worst-case time complexity of the following sort (e.g. /b/2351871).
// These sections will not contribute to the difficulty.
if (peak > 0)
peaks.Add(peak);
}
double difficulty = 0;
double weight = 1;
foreach (double strain in peaks.OrderByDescending(d => d))
{
difficulty += strain * weight;
weight *= 0.9;
}
return difficulty;
}
}
}