mirror of
https://github.com/ppy/osu.git
synced 2024-12-17 13:02:56 +08:00
127 lines
4.9 KiB
C#
127 lines
4.9 KiB
C#
// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
|
|
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
|
|
|
|
using System;
|
|
|
|
namespace osu.Game.Rulesets.Taiko.Objects
|
|
{
|
|
internal class TaikoHitObjectDifficulty
|
|
{
|
|
/// <summary>
|
|
/// Factor by how much individual / overall strain decays per second.
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// These values are results of tweaking a lot and taking into account general feedback.
|
|
/// </remarks>
|
|
internal const double DECAY_BASE = 0.30;
|
|
|
|
private const double type_change_bonus = 0.75;
|
|
private const double rhythm_change_bonus = 1.0;
|
|
private const double rhythm_change_base_threshold = 0.2;
|
|
private const double rhythm_change_base = 2.0;
|
|
|
|
internal TaikoHitObject BaseHitObject;
|
|
|
|
/// <summary>
|
|
/// Measures note density in a way
|
|
/// </summary>
|
|
internal double Strain = 1;
|
|
|
|
private double timeElapsed;
|
|
private int sameTypeSince = 1;
|
|
|
|
private bool isRim => BaseHitObject is RimHit;
|
|
|
|
public TaikoHitObjectDifficulty(TaikoHitObject baseHitObject)
|
|
{
|
|
BaseHitObject = baseHitObject;
|
|
}
|
|
|
|
internal void CalculateStrains(TaikoHitObjectDifficulty previousHitObject, double timeRate)
|
|
{
|
|
// Rather simple, but more specialized things are inherently inaccurate due to the big difference playstyles and opinions make.
|
|
// See Taiko feedback thread.
|
|
timeElapsed = (BaseHitObject.StartTime - previousHitObject.BaseHitObject.StartTime) / timeRate;
|
|
double decay = Math.Pow(DECAY_BASE, timeElapsed / 1000);
|
|
|
|
double addition = 1;
|
|
|
|
// Only if we are no slider or spinner we get an extra addition
|
|
if (previousHitObject.BaseHitObject is Hit && BaseHitObject is Hit
|
|
&& BaseHitObject.StartTime - previousHitObject.BaseHitObject.StartTime < 1000) // And we only want to check out hitobjects which aren't so far in the past
|
|
{
|
|
addition += typeChangeAddition(previousHitObject);
|
|
addition += rhythmChangeAddition(previousHitObject);
|
|
}
|
|
|
|
double additionFactor = 1.0;
|
|
// Scale AdditionFactor linearly from 0.4 to 1 for TimeElapsed from 0 to 50
|
|
if (timeElapsed < 50.0)
|
|
additionFactor = 0.4 + 0.6 * timeElapsed / 50.0;
|
|
|
|
Strain = previousHitObject.Strain * decay + addition * additionFactor;
|
|
}
|
|
|
|
private TypeSwitch lastTypeSwitchEven = TypeSwitch.None;
|
|
private double typeChangeAddition(TaikoHitObjectDifficulty previousHitObject)
|
|
{
|
|
// If we don't have the same hit type, trigger a type change!
|
|
if (previousHitObject.isRim != isRim)
|
|
{
|
|
lastTypeSwitchEven = previousHitObject.sameTypeSince % 2 == 0 ? TypeSwitch.Even : TypeSwitch.Odd;
|
|
|
|
// We only want a bonus if the parity of the type switch changes!
|
|
switch (previousHitObject.lastTypeSwitchEven)
|
|
{
|
|
case TypeSwitch.Even:
|
|
if (lastTypeSwitchEven == TypeSwitch.Odd)
|
|
return type_change_bonus;
|
|
break;
|
|
case TypeSwitch.Odd:
|
|
if (lastTypeSwitchEven == TypeSwitch.Even)
|
|
return type_change_bonus;
|
|
break;
|
|
}
|
|
}
|
|
// No type change? Increment counter and keep track of last type switch
|
|
else
|
|
{
|
|
lastTypeSwitchEven = previousHitObject.lastTypeSwitchEven;
|
|
sameTypeSince = previousHitObject.sameTypeSince + 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
private double rhythmChangeAddition(TaikoHitObjectDifficulty previousHitObject)
|
|
{
|
|
// We don't want a division by zero if some random mapper decides to put 2 HitObjects at the same time.
|
|
if (timeElapsed == 0 || previousHitObject.timeElapsed == 0)
|
|
return 0;
|
|
|
|
double timeElapsedRatio = Math.Max(previousHitObject.timeElapsed / timeElapsed, timeElapsed / previousHitObject.timeElapsed);
|
|
|
|
if (timeElapsedRatio >= 8)
|
|
return 0;
|
|
|
|
double difference = Math.Log(timeElapsedRatio, rhythm_change_base) % 1.0;
|
|
|
|
if (isWithinChangeThreshold(difference))
|
|
return rhythm_change_bonus;
|
|
|
|
return 0;
|
|
}
|
|
|
|
private bool isWithinChangeThreshold(double value)
|
|
{
|
|
return value > rhythm_change_base_threshold && value < 1 - rhythm_change_base_threshold;
|
|
}
|
|
|
|
private enum TypeSwitch
|
|
{
|
|
None,
|
|
Even,
|
|
Odd
|
|
}
|
|
}
|
|
} |