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osu-lazer/osu.Game.Rulesets.Mania/Difficulty/Skills/Strain.cs
Samuel Cattini-Schultz 85d2b1232a Refactor to abstract out strain logic into StrainSkill class
While it is the case for the existing official Skills, Skill implementations shouldn't be required to conform to a strain based approach.
There are other valid approaches to calculating skill difficulty that can be supported by abstracting the strain logic into its own StrainSkill class.
2021-04-03 20:52:39 +11:00

82 lines
3.5 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 osu.Framework.Utils;
using osu.Game.Rulesets.Difficulty.Preprocessing;
using osu.Game.Rulesets.Difficulty.Skills;
using osu.Game.Rulesets.Mania.Difficulty.Preprocessing;
using osu.Game.Rulesets.Mods;
namespace osu.Game.Rulesets.Mania.Difficulty.Skills
{
public class Strain : StrainSkill
{
private const double individual_decay_base = 0.125;
private const double overall_decay_base = 0.30;
protected override double SkillMultiplier => 1;
protected override double StrainDecayBase => 1;
private readonly double[] holdEndTimes;
private readonly double[] individualStrains;
private double individualStrain;
private double overallStrain;
public Strain(Mod[] mods, int totalColumns)
: base(mods)
{
holdEndTimes = new double[totalColumns];
individualStrains = new double[totalColumns];
overallStrain = 1;
}
protected override double StrainValueOf(DifficultyHitObject current)
{
var maniaCurrent = (ManiaDifficultyHitObject)current;
var endTime = maniaCurrent.EndTime;
var column = maniaCurrent.BaseObject.Column;
double holdFactor = 1.0; // Factor to all additional strains in case something else is held
double holdAddition = 0; // Addition to the current note in case it's a hold and has to be released awkwardly
// Fill up the holdEndTimes array
for (int i = 0; i < holdEndTimes.Length; ++i)
{
// If there is at least one other overlapping end or note, then we get an addition, buuuuuut...
if (Precision.DefinitelyBigger(holdEndTimes[i], maniaCurrent.StartTime, 1) && Precision.DefinitelyBigger(endTime, holdEndTimes[i], 1))
holdAddition = 1.0;
// ... this addition only is valid if there is _no_ other note with the same ending. Releasing multiple notes at the same time is just as easy as releasing 1
if (Precision.AlmostEquals(endTime, holdEndTimes[i], 1))
holdAddition = 0;
// We give a slight bonus to everything if something is held meanwhile
if (Precision.DefinitelyBigger(holdEndTimes[i], endTime, 1))
holdFactor = 1.25;
// Decay individual strains
individualStrains[i] = applyDecay(individualStrains[i], current.DeltaTime, individual_decay_base);
}
holdEndTimes[column] = endTime;
// Increase individual strain in own column
individualStrains[column] += 2.0 * holdFactor;
individualStrain = individualStrains[column];
overallStrain = applyDecay(overallStrain, current.DeltaTime, overall_decay_base) + (1 + holdAddition) * holdFactor;
return individualStrain + overallStrain - CurrentStrain;
}
protected override double GetPeakStrain(double offset)
=> applyDecay(individualStrain, offset - Previous[0].StartTime, individual_decay_base)
+ applyDecay(overallStrain, offset - Previous[0].StartTime, overall_decay_base);
private double applyDecay(double value, double deltaTime, double decayBase)
=> value * Math.Pow(decayBase, deltaTime / 1000);
}
}