Reduce implementation overhead in actually positioning hitobjects and making them scroll.

osu.Game/Rulesets/Objects/Drawables/DrawableScrollingHitObject.cs

@@ -3,6 +3,7 @@
 
 using System;
 using osu.Framework.Configuration;
+using osu.Framework.Graphics;
 using osu.Game.Rulesets.Judgements;
 using osu.Game.Rulesets.Objects.Types;
 
@@ -17,6 +18,19 @@ namespace osu.Game.Rulesets.Objects.Drawables
     {
         public BindableDouble LifetimeOffset { get; } = new BindableDouble();
 
+        Axes IScrollingHitObject.ScrollingAxes
+        {
+            set
+            {
+                RelativePositionAxes = value;
+
+                if ((value & Axes.X) > 0)
+                    X = (float)HitObject.StartTime;
+                if ((value & Axes.Y) > 0)
+                    Y = (float)HitObject.StartTime;
+            }
+        }
+
         protected DrawableScrollingHitObject(TObject hitObject)
             : base(hitObject)
         {

osu.Game/Rulesets/Objects/Drawables/IScrollingHitObject.cs

@@ -9,7 +9,7 @@ namespace osu.Game.Rulesets.Objects.Drawables
     /// <summary>
     /// An interface that exposes properties required for scrolling hit objects to be properly displayed.
     /// </summary>
-    public interface IScrollingHitObject : IDrawable
+    internal interface IScrollingHitObject : IDrawable
     {
         /// <summary>
         /// Time offset before the hit object start time at which this <see cref="IScrollingHitObject"/> becomes visible and the time offset
@@ -21,5 +21,11 @@ namespace osu.Game.Rulesets.Objects.Drawables
         /// </para>
         /// </summary>
         BindableDouble LifetimeOffset { get; }
+
+        /// <summary>
+        /// Axes which this <see cref="IScrollingHitObject"/> will scroll through.
+        /// This is set by the container which this scrolls through.
+        /// </summary>
+        Axes ScrollingAxes { set; }
     }
 }