Add gravity mod.

osu.Game.Rulesets.Mania/ManiaRuleset.cs

@@ -89,6 +89,7 @@ namespace osu.Game.Rulesets.Mania
                                 new ModCinema(),
                             },
                         },
+                        new ManiaModGravity()
                     };
 
                 default:

osu.Game.Rulesets.Mania/Mods/ManiaModGravity.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using osu.Game.Rulesets.Mania.Objects;
+using osu.Game.Rulesets.Mania.UI;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.UI;
+using osu.Game.Rulesets.Mania.Timing;
+using osu.Game.Rulesets.Mania.Timing.Drawables;
+using osu.Game.Rulesets.Objects.Types;
+using System.Linq;
+using osu.Framework.Lists;
+using osu.Game.Beatmaps.ControlPoints;
+using osu.Framework.MathUtils;
+
+namespace osu.Game.Rulesets.Mania.Mods
+{
+    public class ManiaModGravity : Mod, IApplicableMod<ManiaHitObject>
+    {
+        public override string Name => "Gravity";
+
+        public override double ScoreMultiplier => 0;
+
+        public void ApplyToHitRenderer(HitRenderer<ManiaHitObject> hitRenderer)
+        {
+            var maniaHitRenderer = (ManiaHitRenderer)hitRenderer;
+
+            maniaHitRenderer.HitObjectTimingChanges = new Dictionary<int, List<DrawableTimingChange>>();
+            maniaHitRenderer.BarlineTimingChanges = new List<DrawableTimingChange>();
+
+            foreach (ManiaHitObject obj in maniaHitRenderer.Objects)
+            {
+                List<DrawableTimingChange> timingChanges;
+                if (!maniaHitRenderer.HitObjectTimingChanges.TryGetValue(obj.Column, out timingChanges))
+                    maniaHitRenderer.HitObjectTimingChanges[obj.Column] = timingChanges = new List<DrawableTimingChange>();
+
+                timingChanges.Add(new DrawableGravityTimingChange(new TimingChange
+                {
+                    Time = obj.StartTime,
+                    BeatLength = 1000
+                }));
+            }
+
+            double lastObjectTime = (maniaHitRenderer.Objects.LastOrDefault() as IHasEndTime)?.EndTime ?? maniaHitRenderer.Objects.LastOrDefault()?.StartTime ?? double.MaxValue;
+
+            SortedList<TimingControlPoint> timingPoints = maniaHitRenderer.Beatmap.ControlPointInfo.TimingPoints;
+            for (int i = 0; i < timingPoints.Count; i++)
+            {
+                TimingControlPoint point = timingPoints[i];
+
+                // Stop on the beat before the next timing point, or if there is no next timing point stop slightly past the last object
+                double endTime = i < timingPoints.Count - 1 ? timingPoints[i + 1].Time - point.BeatLength : lastObjectTime + point.BeatLength * (int)point.TimeSignature;
+
+                int index = 0;
+                for (double t = timingPoints[i].Time; Precision.DefinitelyBigger(endTime, t); t += point.BeatLength, index++)
+                {
+                    maniaHitRenderer.BarlineTimingChanges.Add(new DrawableGravityTimingChange(new TimingChange
+                    {
+                        Time = t,
+                        BeatLength = 1000
+                    }));
+                }
+            }
+        }
+    }
+}

osu.Game.Rulesets.Mania/Timing/TimingChangeContainer.cs

@@ -42,7 +42,7 @@ namespace osu.Game.Rulesets.Mania.Timing
         /// </summary>
         /// <param name="hitObject">The hit object to contain.</param>
         /// <returns>The last timing change which can contain <paramref name="hitObject"/>. Null if no timing change can contain the hit object.</returns>
-        private DrawableTimingChange timingChangeFor(DrawableHitObject hitObject) => Children.FirstOrDefault(c => c.CanContain(hitObject));
+        private DrawableTimingChange timingChangeFor(DrawableHitObject hitObject) => Children.FirstOrDefault(c => c.CanContain(hitObject)) ?? Children.LastOrDefault();
     }
 
     /// <summary>

osu.Game.Rulesets.Mania/UI/ManiaHitRenderer.cs

@@ -31,15 +31,26 @@ namespace osu.Game.Rulesets.Mania.UI
 {
     public class ManiaHitRenderer : HitRenderer<ManiaHitObject, ManiaJudgement>
     {
-        public int? Columns;
+        private int? columns;
+        public int Columns => columns ?? (int)Math.Round(Beatmap.BeatmapInfo.Difficulty.CircleSize);
+
+        public Dictionary<int, List<DrawableTimingChange>> HitObjectTimingChanges;
+        public List<DrawableTimingChange> BarlineTimingChanges;
 
         public ManiaHitRenderer(WorkingBeatmap beatmap, bool isForCurrentRuleset)
             : base(beatmap, isForCurrentRuleset)
         {
+            generateTimingChanges();
         }
 
-        protected override Playfield<ManiaHitObject, ManiaJudgement> CreatePlayfield()
+        private void generateTimingChanges()
         {
+            if (HitObjectTimingChanges != null || BarlineTimingChanges != null)
+                return;
+
+            HitObjectTimingChanges = new Dictionary<int, List<DrawableTimingChange>>();
+            BarlineTimingChanges = new List<DrawableTimingChange>();
+
             double lastSpeedMultiplier = 1;
             double lastBeatLength = 500;
 
@@ -80,7 +91,24 @@ namespace osu.Game.Rulesets.Mania.UI
                 .GroupBy(s => s.BeatLength * s.SpeedMultiplier).Select(g => g.First())
                 .ToList();
 
-            var playfield = new ManiaPlayfield(Columns ?? (int)Math.Round(Beatmap.BeatmapInfo.Difficulty.CircleSize))
+            timingChanges.ForEach(t =>
+            {
+                for (int i = 0; i < Columns; i++)
+                {
+                    List<DrawableTimingChange> columnTimingChanges;
+                    if (!HitObjectTimingChanges.TryGetValue(i, out columnTimingChanges))
+                        HitObjectTimingChanges[i] = columnTimingChanges = new List<DrawableTimingChange>();
+
+                    columnTimingChanges.Add(new DrawableScrollingTimingChange(t));
+                }
+
+                BarlineTimingChanges.Add(new DrawableScrollingTimingChange(t));
+            });
+        }
+
+        protected override Playfield<ManiaHitObject, ManiaJudgement> CreatePlayfield()
+        {
+            var playfield = new ManiaPlayfield(Columns)
             {
                 Anchor = Anchor.Centre,
                 Origin = Anchor.Centre,
@@ -88,8 +116,17 @@ namespace osu.Game.Rulesets.Mania.UI
                 Scale = new Vector2(1, -1)
             };
 
-            timingChanges.ForEach(t => playfield.Columns.ForEach(c => c.Add(new DrawableScrollingTimingChange(t))));
-            timingChanges.ForEach(t => playfield.Add(new DrawableScrollingTimingChange(t)));
+            foreach (var kvp in HitObjectTimingChanges)
+            {
+                int column = kvp.Key;
+                List<DrawableTimingChange> timingChanges = kvp.Value;
+
+                foreach (var change in timingChanges)
+                    playfield.Columns.ElementAt(column).Add(change);
+            }
+
+            foreach (var change in BarlineTimingChanges)
+                playfield.Add(change);
 
             return playfield;
         }

osu.Game.Rulesets.Mania/osu.Game.Rulesets.Mania.csproj

@@ -82,6 +82,7 @@
     <Compile Include="UI\ManiaPlayfield.cs" />
     <Compile Include="ManiaRuleset.cs" />
     <Compile Include="Mods\ManiaMod.cs" />
+    <Compile Include="Mods\ManiaModGravity.cs" />
     <Compile Include="UI\SpecialColumnPosition.cs" />
     <Compile Include="Timing\Drawables\DrawableGravityTimingChange.cs" />
     <Compile Include="Timing\Drawables\DrawableScrollingTimingChange.cs" />