mirror of
https://github.com/ppy/osu.git
synced 2024-12-14 23:12:56 +08:00
147 lines
6.3 KiB
C#
147 lines
6.3 KiB
C#
// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
|
|
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
|
|
|
|
using osu.Game.Beatmaps;
|
|
using osu.Game.Rulesets.Mania.Beatmaps;
|
|
using osu.Game.Rulesets.Mania.Objects;
|
|
using osu.Game.Rulesets.Mods;
|
|
using System;
|
|
using System.Collections.Generic;
|
|
|
|
namespace osu.Game.Rulesets.Mania
|
|
{
|
|
internal class ManiaDifficultyCalculator : DifficultyCalculator<ManiaHitObject>
|
|
{
|
|
private const double star_scaling_factor = 0.018;
|
|
|
|
/// <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 = 400;
|
|
|
|
/// <summary>
|
|
/// The weighting of each strain value decays to this number * it's previous value
|
|
/// </summary>
|
|
private const double decay_weight = 0.9;
|
|
|
|
/// <summary>
|
|
/// HitObjects are stored as a member variable.
|
|
/// </summary>
|
|
private readonly List<ManiaHitObjectDifficulty> difficultyHitObjects = new List<ManiaHitObjectDifficulty>();
|
|
|
|
public ManiaDifficultyCalculator(Beatmap beatmap)
|
|
: base(beatmap)
|
|
{
|
|
}
|
|
|
|
public ManiaDifficultyCalculator(Beatmap beatmap, Mod[] mods)
|
|
: base(beatmap, mods)
|
|
{
|
|
}
|
|
|
|
public override double Calculate(Dictionary<string, double> categoryDifficulty = null)
|
|
{
|
|
// Fill our custom DifficultyHitObject class, that carries additional information
|
|
difficultyHitObjects.Clear();
|
|
|
|
int columnCount = (Beatmap as ManiaBeatmap)?.TotalColumns ?? 7;
|
|
|
|
foreach (var hitObject in Beatmap.HitObjects)
|
|
difficultyHitObjects.Add(new ManiaHitObjectDifficulty(hitObject, columnCount));
|
|
|
|
// Sort DifficultyHitObjects by StartTime of the HitObjects - just to make sure.
|
|
difficultyHitObjects.Sort((a, b) => a.BaseHitObject.StartTime.CompareTo(b.BaseHitObject.StartTime));
|
|
|
|
if (!calculateStrainValues())
|
|
return 0;
|
|
|
|
double starRating = calculateDifficulty() * star_scaling_factor;
|
|
|
|
categoryDifficulty?.Add("Strain", starRating);
|
|
|
|
return starRating;
|
|
}
|
|
|
|
private bool calculateStrainValues()
|
|
{
|
|
// Traverse hitObjects in pairs to calculate the strain value of NextHitObject from the strain value of CurrentHitObject and environment.
|
|
using (List<ManiaHitObjectDifficulty>.Enumerator hitObjectsEnumerator = difficultyHitObjects.GetEnumerator())
|
|
{
|
|
if (!hitObjectsEnumerator.MoveNext())
|
|
return false;
|
|
|
|
ManiaHitObjectDifficulty current = hitObjectsEnumerator.Current;
|
|
|
|
// First hitObject starts at strain 1. 1 is the default for strain values, so we don't need to set it here. See DifficultyHitObject.
|
|
while (hitObjectsEnumerator.MoveNext())
|
|
{
|
|
var next = hitObjectsEnumerator.Current;
|
|
next?.CalculateStrains(current, TimeRate);
|
|
current = next;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
}
|
|
|
|
private double calculateDifficulty()
|
|
{
|
|
double actualStrainStep = strain_step * TimeRate;
|
|
|
|
// Find the highest strain value within each strain step
|
|
List<double> highestStrains = new List<double>();
|
|
double intervalEndTime = actualStrainStep;
|
|
double maximumStrain = 0; // We need to keep track of the maximum strain in the current interval
|
|
|
|
ManiaHitObjectDifficulty previousHitObject = null;
|
|
foreach (var hitObject in difficultyHitObjects)
|
|
{
|
|
// 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 individualDecay = Math.Pow(ManiaHitObjectDifficulty.INDIVIDUAL_DECAY_BASE, (intervalEndTime - previousHitObject.BaseHitObject.StartTime) / 1000);
|
|
double overallDecay = Math.Pow(ManiaHitObjectDifficulty.OVERALL_DECAY_BASE, (intervalEndTime - previousHitObject.BaseHitObject.StartTime) / 1000);
|
|
maximumStrain = previousHitObject.IndividualStrain * individualDecay + previousHitObject.OverallStrain * overallDecay;
|
|
}
|
|
|
|
// Go to the next time interval
|
|
intervalEndTime += actualStrainStep;
|
|
}
|
|
|
|
// Obtain maximum strain
|
|
double strain = hitObject.IndividualStrain + hitObject.OverallStrain;
|
|
maximumStrain = Math.Max(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;
|
|
}
|
|
|
|
protected override BeatmapConverter<ManiaHitObject> CreateBeatmapConverter(Beatmap beatmap) => new ManiaBeatmapConverter(true, beatmap);
|
|
}
|
|
}
|