Fix animated follow points not (re)animating after rewind

osu.Game.Rulesets.Osu/Objects/Drawables/Connections/FollowPoint.cs

@@ -15,7 +15,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Connections
     /// <summary>
     /// A single follow point positioned between two adjacent <see cref="DrawableOsuHitObject"/>s.
     /// </summary>
-    public class FollowPoint : Container
+    public class FollowPoint : Container, IAnimationTimeReference
     {
         private const float width = 8;
 
@@ -45,5 +45,7 @@ public FollowPoint()
                 }
             }, confineMode: ConfineMode.NoScaling);
         }
+
+        public double AnimationStartTime { get; set; }
     }
 }

osu.Game.Rulesets.Osu/Objects/Drawables/Connections/FollowPointConnection.cs

@@ -116,6 +116,8 @@ private void refresh()
 
             int point = 0;
 
+            ClearInternal();
+
             for (int d = (int)(spacing * 1.5); d < distance - spacing; d += spacing)
             {
                 float fraction = (float)d / distance;
@@ -126,13 +128,7 @@ private void refresh()
 
                 FollowPoint fp;
 
-                if (InternalChildren.Count > point)
-                {
-                    fp = (FollowPoint)InternalChildren[point];
-                    fp.ClearTransforms();
-                }
-                else
-                    AddInternal(fp = new FollowPoint());
+                AddInternal(fp = new FollowPoint());
 
                 fp.Position = pointStartPosition;
                 fp.Rotation = rotation;
@@ -142,6 +138,8 @@ private void refresh()
                 if (firstTransformStartTime == null)
                     firstTransformStartTime = fadeInTime;
 
+                fp.AnimationStartTime = fadeInTime;
+
                 using (fp.BeginAbsoluteSequence(fadeInTime))
                 {
                     fp.FadeIn(osuEnd.TimeFadeIn);

osu.Game/Skinning/IAnimationTimeReference.cs

@@ -0,0 +1,25 @@
+// 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 osu.Framework.Allocation;
+using osu.Framework.Timing;
+
+namespace osu.Game.Skinning
+{
+    /// <summary>
+    /// Denotes an object which provides a reference time to start animations from.
+    /// </summary>
+    [Cached]
+    public interface IAnimationTimeReference
+    {
+        /// <summary>
+        /// The reference clock.
+        /// </summary>
+        IFrameBasedClock Clock { get; }
+
+        /// <summary>
+        /// The time which animations should be started from, relative to <see cref="Clock"/>.
+        /// </summary>
+        double AnimationStartTime { get; }
+    }
+}

osu.Game/Skinning/LegacySkinExtensions.cs

@@ -3,10 +3,12 @@
 
 using System.Collections.Generic;
 using System.Linq;
+using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Animations;
 using osu.Framework.Graphics.Sprites;
 using osu.Framework.Graphics.Textures;
+using osu.Framework.Timing;
 
 namespace osu.Game.Skinning
 {
@@ -22,7 +24,7 @@ public static Drawable GetAnimation(this ISkin source, string componentName, boo
 
                 if (textures.Length > 0)
                 {
-                    var animation = new TextureAnimation
+                    var animation = new SkinnableTextureAnimation
                     {
                         DefaultFrameLength = getFrameLength(source, applyConfigFrameRate, textures),
                         Repeat = looping,
@@ -53,6 +55,25 @@ IEnumerable<Texture> getTextures()
             }
         }
 
+        public class SkinnableTextureAnimation : TextureAnimation
+        {
+            [Resolved(canBeNull: true)]
+            private IAnimationTimeReference timeReference { get; set; }
+
+            public SkinnableTextureAnimation()
+                : base(false)
+            {
+            }
+
+            protected override void LoadComplete()
+            {
+                base.LoadComplete();
+
+                if (timeReference != null)
+                    Clock = new FramedOffsetClock(timeReference.Clock) { Offset = -timeReference.AnimationStartTime };
+            }
+        }
+
         private const double default_frame_time = 1000 / 60d;
 
         private static double getFrameLength(ISkin source, bool applyConfigFrameRate, Texture[] textures)