Merge pull request #20253 from peppy/fix-execute-me-storyboard

Fix `world.execute(me)` storyboard animation incorrectness

osu.Game.Tests/Beatmaps/Formats/LegacyStoryboardDecoderTest.cs

@@ -97,6 +97,25 @@ namespace osu.Game.Tests.Beatmaps.Formats
             }
         }
 
+        [Test]
+        public void TestCorrectAnimationStartTime()
+        {
+            var decoder = new LegacyStoryboardDecoder();
+
+            using (var resStream = TestResources.OpenResource("animation-starts-before-alpha.osb"))
+            using (var stream = new LineBufferedReader(resStream))
+            {
+                var storyboard = decoder.Decode(stream);
+
+                StoryboardLayer background = storyboard.Layers.Single(l => l.Depth == 3);
+                Assert.AreEqual(1, background.Elements.Count);
+
+                Assert.AreEqual(2000, background.Elements[0].StartTime);
+                // This property should be used in DrawableStoryboardAnimation as a starting point for animation playback.
+                Assert.AreEqual(1000, (background.Elements[0] as StoryboardAnimation)?.EarliestTransformTime);
+            }
+        }
+
         [Test]
         public void TestOutOfOrderStartTimes()
         {

osu.Game.Tests/Resources/animation-starts-before-alpha.osb

@@ -0,0 +1,5 @@
+[Events]
+//Storyboard Layer 0 (Background)
+Animation,Background,Centre,"img.jpg",320,240,2,150,LoopForever
+ S,0,1000,1500,0.08 // animation should start playing from this point in time..
+ F,0,2000,,0,1      // .. not this point in time

osu.Game/Storyboards/Drawables/DrawableStoryboardAnimation.cs

@@ -10,6 +10,7 @@ using osu.Framework.Graphics;
 using osu.Framework.Graphics.Animations;
 using osu.Framework.Graphics.Textures;
 using osu.Framework.Utils;
+using osu.Game.Screens.Play;
 using osu.Game.Skinning;
 using osuTK;
 
@@ -115,6 +116,21 @@ namespace osu.Game.Storyboards.Drawables
             Animation.ApplyTransforms(this);
         }
 
+        [Resolved]
+        private IGameplayClock gameplayClock { get; set; }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            // Framework animation class tries its best to synchronise the animation at LoadComplete,
+            // but in some cases (such as fast forward) this results in an incorrect start offset.
+            //
+            // In the case of storyboard animations, we want to synchronise with game time perfectly
+            // so let's get a correct time based on gameplay clock and earliest transform.
+            PlaybackPosition = gameplayClock.CurrentTime - Animation.EarliestTransformTime;
+        }
+
         private void skinSourceChanged()
         {
             ClearFrames();

osu.Game/Storyboards/StoryboardSprite.cs

@@ -54,6 +54,14 @@ namespace osu.Game.Storyboards
                         return firstAlpha.startTime;
                 }
 
+                return EarliestTransformTime;
+            }
+        }
+
+        public double EarliestTransformTime
+        {
+            get
+            {
                 // If we got to this point, either no alpha commands were present, or the earliest had a non-zero start value.
                 // The sprite's StartTime will be determined by the earliest command, regardless of type.
                 double earliestStartTime = TimelineGroup.StartTime;