Add "Whiplash" mod for osu! ruleset

osu.Game.Rulesets.Osu/Mods/OsuModWhiplash.cs

@@ -0,0 +1,93 @@
+// 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.Bindables;
+using osu.Framework.Localisation;
+using osu.Game.Beatmaps;
+using osu.Game.Configuration;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Osu.Objects;
+
+namespace osu.Game.Rulesets.Osu.Mods
+{
+    public class OsuModWhiplash : Mod, IApplicableToHitObject, IApplicableToBeatmapProcessor
+    {
+        public override string Name => "Whiplash";
+        public override string Acronym => "WL";
+        public override LocalisableString Description => "Am I rushing.. or am I dragging?";
+        public override ModType Type => ModType.Conversion;
+
+        private IBeatmap? currentBeatmap { get; set; }
+
+        [SettingSource("Target BPM", "Target BPM to center the changes around.")]
+        public Bindable<TargetBPMStyle> TargetBPM { get; } = new Bindable<TargetBPMStyle>(TargetBPMStyle.MaxBPM);
+
+        public override double ScoreMultiplier => TargetBPM.Value == TargetBPMStyle.MaxBPM ? 1.0 : 0.75;
+
+        public void ApplyToHitObject(HitObject hitObject)
+        {
+            if (currentBeatmap == null || hitObject is not OsuHitObject hitCircle)
+                return;
+
+            double currentBpm = currentBeatmap.ControlPointInfo.TimingPointAt(hitCircle.StartTime).BPM;
+
+            if (currentBpm < 1)
+            {
+                updateTimePreempty(hitCircle, hitCircle.StartTime);
+                return;
+            }
+
+            double scaleBpm = getBaseBPM(currentBeatmap);
+            double preempt = hitCircle.TimePreempt;
+            double newTimePreempt = (scaleBpm / Math.Max(currentBpm, 1)) * preempt;
+
+            //don't allow AR to go over 11
+            updateTimePreempty(hitCircle, Math.Max(newTimePreempt, 300));
+        }
+
+        private void updateTimePreempty(OsuHitObject hitCircle, double value)
+        {
+            hitCircle.TimePreempt = value;
+
+            if (hitCircle is Slider slider)
+            {
+                slider.HeadCircle.TimePreempt = value;
+            }
+        }
+
+        private double getBaseBPM(IBeatmap beatmap)
+        {
+            switch (TargetBPM.Value)
+            {
+                case TargetBPMStyle.MainBPM:
+                    return beatmap.BeatmapInfo.BPM;
+
+                case TargetBPMStyle.MaxBPM:
+                    return beatmap.ControlPointInfo.BPMMaximum;
+
+                case TargetBPMStyle.MinBPM:
+                    return beatmap.ControlPointInfo.BPMMinimum;
+
+                default:
+                    throw new ArgumentOutOfRangeException(nameof(TargetBPM), TargetBPM, @"Unsupported BPM scale");
+            }
+        }
+
+        public void ApplyToBeatmapProcessor(IBeatmapProcessor beatmapProcessor)
+        {
+            if (currentBeatmap != beatmapProcessor.Beatmap)
+            {
+                currentBeatmap = beatmapProcessor.Beatmap;
+            }
+        }
+
+        public enum TargetBPMStyle
+        {
+            MainBPM,
+            MinBPM,
+            MaxBPM,
+        }
+    }
+}

osu.Game.Rulesets.Osu/OsuRuleset.cs

@@ -183,7 +183,8 @@ namespace osu.Game.Rulesets.Osu
                         new OsuModClassic(),
                         new OsuModRandom(),
                         new OsuModMirror(),
-                        new MultiMod(new OsuModAlternate(), new OsuModSingleTap())
+                        new MultiMod(new OsuModAlternate(), new OsuModSingleTap()),
+                        new OsuModWhiplash()
                     };
 
                 case ModType.Automation: