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osu-lazer/osu.Game.Rulesets.Mania/Difficulty/Skills/Strain.cs
2023-06-24 01:00:03 +09:00

102 lines
4.8 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 : StrainDecaySkill
{
private const double individual_decay_base = 0.125;
private const double overall_decay_base = 0.30;
private const double release_threshold = 24;
protected override double SkillMultiplier => 1;
protected override double StrainDecayBase => 1;
private readonly double[] startTimes;
private readonly double[] endTimes;
private readonly double[] individualStrains;
private double individualStrain;
private double overallStrain;
public Strain(Mod[] mods, int totalColumns)
: base(mods)
{
startTimes = new double[totalColumns];
endTimes = new double[totalColumns];
individualStrains = new double[totalColumns];
overallStrain = 1;
}
protected override double StrainValueOf(DifficultyHitObject current)
{
var maniaCurrent = (ManiaDifficultyHitObject)current;
double startTime = maniaCurrent.StartTime;
double endTime = maniaCurrent.EndTime;
int column = maniaCurrent.BaseObject.Column;
bool isOverlapping = false;
double closestEndTime = Math.Abs(endTime - startTime); // Lowest value we can assume with the current information
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
for (int i = 0; i < endTimes.Length; ++i)
{
// The current note is overlapped if a previous note or end is overlapping the current note body
isOverlapping |= Precision.DefinitelyBigger(endTimes[i], startTime, 1) && Precision.DefinitelyBigger(endTime, endTimes[i], 1);
// We give a slight bonus to everything if something is held meanwhile
if (Precision.DefinitelyBigger(endTimes[i], endTime, 1))
holdFactor = 1.25;
closestEndTime = Math.Min(closestEndTime, Math.Abs(endTime - endTimes[i]));
}
// The hold addition is given if there was an overlap, however it is only valid if there are no other note with a similar ending.
// Releasing multiple notes is just as easy as releasing 1. Nerfs the hold addition by half if the closest release is release_threshold away.
// holdAddition
// ^
// 1.0 + - - - - - -+-----------
// | /
// 0.5 + - - - - -/ Sigmoid Curve
// | /|
// 0.0 +--------+-+---------------> Release Difference / ms
// release_threshold
if (isOverlapping)
holdAddition = 1 / (1 + Math.Exp(0.5 * (release_threshold - closestEndTime)));
// Decay and increase individualStrains in own column
individualStrains[column] = applyDecay(individualStrains[column], startTime - startTimes[column], individual_decay_base);
individualStrains[column] += 2.0 * holdFactor;
// For notes at the same time (in a chord), the individualStrain should be the hardest individualStrain out of those columns
individualStrain = maniaCurrent.DeltaTime <= 1 ? Math.Max(individualStrain, individualStrains[column]) : individualStrains[column];
// Decay and increase overallStrain
overallStrain = applyDecay(overallStrain, current.DeltaTime, overall_decay_base);
overallStrain += (1 + holdAddition) * holdFactor;
// Update startTimes and endTimes arrays
startTimes[column] = startTime;
endTimes[column] = endTime;
// By subtracting CurrentStrain, this skill effectively only considers the maximum strain of any one hitobject within each strain section.
return individualStrain + overallStrain - CurrentStrain;
}
protected override double CalculateInitialStrain(double offset, DifficultyHitObject current)
=> applyDecay(individualStrain, offset - current.Previous(0).StartTime, individual_decay_base)
+ applyDecay(overallStrain, offset - current.Previous(0).StartTime, overall_decay_base);
private double applyDecay(double value, double deltaTime, double decayBase)
=> value * Math.Pow(decayBase, deltaTime / 1000);
}
}