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osu-lazer/osu.Game.Rulesets.Taiko/Difficulty/Evaluators/StaminaEvaluator.cs

76 lines
3.1 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.Game.Rulesets.Difficulty.Preprocessing;
using osu.Game.Rulesets.Taiko.Difficulty.Preprocessing;
using osu.Game.Rulesets.Taiko.Objects;
namespace osu.Game.Rulesets.Taiko.Difficulty.Evaluators
{
public class StaminaEvaluator
{
/// <summary>
/// Applies a speed bonus dependent on the time since the last hit performed using this finger.
/// </summary>
/// <param name="interval">The interval between the current and previous note hit using the same finger.</param>
private static double speedBonus(double interval)
{
// Interval is capped at a very small value to prevent infinite values.
interval = Math.Max(interval, 1);
return 30 / interval;
}
/// <summary>
/// Determines the number of fingers available to hit the current <see cref="TaikoDifficultyHitObject"/>.
/// Any mono notes that is more than 300ms apart from a colour change will be considered to have more than 2
/// fingers available, since players can hit the same key with multiple fingers.
/// </summary>
private static int availableFingersFor(TaikoDifficultyHitObject hitObject)
{
DifficultyHitObject? previousColourChange = hitObject.Colour.PreviousColourChange;
DifficultyHitObject? nextColourChange = hitObject.Colour.NextColourChange;
if (previousColourChange != null && hitObject.StartTime - previousColourChange.StartTime < 300)
{
return 2;
}
if (nextColourChange != null && nextColourChange.StartTime - hitObject.StartTime < 300)
{
return 2;
}
return 4;
}
/// <summary>
/// Evaluates the minimum mechanical stamina required to play the current object. This is calculated using the
/// maximum possible interval between two hits using the same key, by alternating available fingers for each colour.
/// </summary>
public static double EvaluateDifficultyOf(DifficultyHitObject current)
{
if (current.BaseObject is not Hit)
{
return 0.0;
}
// Find the previous hit object hit by the current finger, which is n notes prior, n being the number of
// available fingers.
TaikoDifficultyHitObject taikoCurrent = (TaikoDifficultyHitObject)current;
TaikoDifficultyHitObject? keyPrevious = taikoCurrent.PreviousMono(availableFingersFor(taikoCurrent) - 1);
if (keyPrevious == null)
{
// There is no previous hit object hit by the current finger
return 0.0;
}
double objectStrain = 0.5; // Add a base strain to all objects
objectStrain += speedBonus(taikoCurrent.StartTime - keyPrevious.StartTime);
return objectStrain;
}
}
}