ManiaModHoldOff.cs

// 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 System.Collections.Generic;
using System.Linq;
using osu.Framework.Graphics.Sprites;
using osu.Framework.Localisation;
using osu.Framework.Utils;
using osu.Game.Beatmaps;
using osu.Game.Graphics;
using osu.Game.Rulesets.Mania.Beatmaps;
using osu.Game.Rulesets.Mania.Objects;
using osu.Game.Rulesets.Mods;

namespace osu.Game.Rulesets.Mania.Mods
{
    public class ManiaModHoldOff : Mod, IApplicableAfterBeatmapConversion
    {
        public override string Name => "Hold Off";

        public override string Acronym => "HO";

        public override LocalisableString Description => @"Replaces all hold notes with normal notes.";

        public override IconUsage? Icon => OsuIcon.ModHoldOff;

        public override ModType Type => ModType.Conversion;

        public override Type[] IncompatibleMods => new[] { typeof(ManiaModInvert), typeof(ManiaModNoRelease) };

        public void ApplyToBeatmap(IBeatmap beatmap)
        {
            var maniaBeatmap = (ManiaBeatmap)beatmap;

            double mostCommonBeatLengthBefore = beatmap.GetMostCommonBeatLength();

            var newObjects = new List<ManiaHitObject>();

            foreach (var h in beatmap.HitObjects.OfType<HoldNote>())
            {
                // Add a note for the beginning of the hold note
                newObjects.Add(new Note
                {
                    Column = h.Column,
                    StartTime = h.StartTime,
                    Samples = h.GetNodeSamples(0)
                });
            }

            maniaBeatmap.HitObjects = maniaBeatmap.HitObjects.OfType<Note>().Concat(newObjects).OrderBy(h => h.StartTime).ToList();

            double mostCommonBeatLengthAfter = beatmap.GetMostCommonBeatLength();

            // the process of removing hold notes can result in shortening the beatmap's play time,
            // and therefore, as a side effect, changing the most common BPM, which will change scroll speed.
            // to compensate for this, apply a multiplier to effect points in order to maintain the beatmap's original intended scroll speed.
            if (!Precision.AlmostEquals(mostCommonBeatLengthBefore, mostCommonBeatLengthAfter))
            {
                foreach (var effectPoint in beatmap.ControlPointInfo.EffectPoints)
                    effectPoint.ScrollSpeed *= mostCommonBeatLengthBefore / mostCommonBeatLengthAfter;
            }
        }
    }
}