Fix sliders not moving with stacking change

osu.Game.Rulesets.Osu.Tests/TestSceneSlider.cs

@@ -111,6 +111,21 @@ public TestSceneSlider()
             AddStep("Distance Overflow 1 Repeat", () => SetContents(() => testDistanceOverflow(1)));
         }
 
+        [Test]
+        public void TestChangeStackHeight()
+        {
+            DrawableSlider slider = null;
+
+            AddStep("create slider", () =>
+            {
+                slider = (DrawableSlider)createSlider(repeats: 1);
+                Add(slider);
+            });
+
+            AddStep("change stack height", () => slider.HitObject.StackHeight = 10);
+            AddAssert("body positioned correctly", () => slider.Position == slider.HitObject.StackedPosition);
+        }
+
         private Drawable testSimpleBig(int repeats = 0) => createSlider(2, repeats: repeats);
 
         private Drawable testSimpleBigLargeStackOffset(int repeats = 0) => createSlider(2, repeats: repeats, stackHeight: 10);

osu.Game.Rulesets.Osu.Tests/TestSceneSliderSelectionBlueprint.cs

@@ -78,6 +78,13 @@ public void TestMoveAfterApplyingDefaults()
             checkPositions();
         }
 
+        [Test]
+        public void TestStackedHitObject()
+        {
+            AddStep("set stacking", () => slider.StackHeight = 5);
+            checkPositions();
+        }
+
         private void moveHitObject()
         {
             AddStep("move hitobject", () =>
@@ -88,7 +95,7 @@ private void moveHitObject()
 
         private void checkPositions()
         {
-            AddAssert("body positioned correctly", () => blueprint.BodyPiece.Position == slider.Position);
+            AddAssert("body positioned correctly", () => blueprint.BodyPiece.Position == slider.StackedPosition);
 
             AddAssert("head positioned correctly",
                 () => Precision.AlmostEquals(blueprint.HeadBlueprint.CirclePiece.ScreenSpaceDrawQuad.Centre, drawableObject.HeadCircle.ScreenSpaceDrawQuad.Centre));

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

@@ -31,6 +31,7 @@ public class DrawableSlider : DrawableOsuHitObject, IDrawableHitObjectWithProxie
         public readonly SliderBall Ball;
 
         private readonly IBindable<Vector2> positionBindable = new Bindable<Vector2>();
+        private readonly IBindable<int> stackHeightBindable = new Bindable<int>();
         private readonly IBindable<float> scaleBindable = new Bindable<float>();
         private readonly IBindable<SliderPath> pathBindable = new Bindable<SliderPath>();
 
@@ -108,6 +109,7 @@ private void load()
             config?.BindWith(OsuRulesetSetting.SnakingOutSliders, Body.SnakingOut);
 
             positionBindable.BindValueChanged(_ => Position = HitObject.StackedPosition);
+            stackHeightBindable.BindValueChanged(_ => Position = HitObject.StackedPosition);
             scaleBindable.BindValueChanged(scale =>
             {
                 updatePathRadius();
@@ -115,6 +117,7 @@ private void load()
             });
 
             positionBindable.BindTo(HitObject.PositionBindable);
+            stackHeightBindable.BindTo(HitObject.StackHeightBindable);
             scaleBindable.BindTo(HitObject.ScaleBindable);
             pathBindable.BindTo(slider.PathBindable);
 

osu.Game.Rulesets.Osu/Objects/OsuHitObject.cs

@@ -1,6 +1,7 @@
 // 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.Linq;
 using osu.Framework.Bindables;
 using osu.Game.Beatmaps;
 using osu.Game.Rulesets.Objects;
@@ -98,6 +99,15 @@ public bool LastInCombo
             set => LastInComboBindable.Value = value;
         }
 
+        protected OsuHitObject()
+        {
+            StackHeightBindable.BindValueChanged(height =>
+            {
+                foreach (var nested in NestedHitObjects.OfType<OsuHitObject>())
+                    nested.StackHeight = height.NewValue;
+            });
+        }
+
         protected override void ApplyDefaultsToSelf(ControlPointInfo controlPointInfo, BeatmapDifficulty difficulty)
         {
             base.ApplyDefaultsToSelf(controlPointInfo, difficulty);

osu.Game.Rulesets.Osu/Objects/Slider.cs

@@ -163,6 +163,7 @@ protected override void CreateNestedHitObjects()
                         {
                             StartTime = e.Time,
                             Position = Position,
+                            StackHeight = StackHeight,
                             Samples = getNodeSamples(0),
                             SampleControlPoint = SampleControlPoint,
                         });
@@ -176,6 +177,7 @@ protected override void CreateNestedHitObjects()
                         {
                             StartTime = e.Time,
                             Position = EndPosition,
+                            StackHeight = StackHeight
                         });
                         break;