Add initial animation for health bars

osu.Game.Tests/Visual/Gameplay/TestSceneSkinnableHealthDisplay.cs

@@ -12,6 +12,7 @@
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Screens.Play.HUD;
 using osu.Game.Skinning;
+using osuTK;
 
 namespace osu.Game.Tests.Visual.Gameplay
 {
@@ -20,9 +21,9 @@ public partial class TestSceneSkinnableHealthDisplay : SkinnableHUDComponentTest
         [Cached(typeof(HealthProcessor))]
         private HealthProcessor healthProcessor = new DrainingHealthProcessor(0);
 
-        protected override Drawable CreateArgonImplementation() => new ArgonHealthDisplay();
-        protected override Drawable CreateDefaultImplementation() => new DefaultHealthDisplay();
-        protected override Drawable CreateLegacyImplementation() => new LegacyHealthDisplay();
+        protected override Drawable CreateArgonImplementation() => new ArgonHealthDisplay { Scale = new Vector2(0.6f) };
+        protected override Drawable CreateDefaultImplementation() => new DefaultHealthDisplay { Scale = new Vector2(0.6f) };
+        protected override Drawable CreateLegacyImplementation() => new LegacyHealthDisplay { Scale = new Vector2(0.6f) };
 
         [SetUpSteps]
         public void SetUpSteps()
@@ -62,4 +63,4 @@ public void TestHealthDisplayIncrementing()
             }, 3);
         }
     }
-}
+}

osu.Game/Screens/Play/HUD/ArgonHealthDisplay.cs

@@ -46,7 +46,7 @@ public partial class ArgonHealthDisplay : HealthDisplay, ISerialisableDrawable
         private readonly List<Vector2> missBarVertices = new List<Vector2>();
         private readonly List<Vector2> healthBarVertices = new List<Vector2>();
 
-        private double glowBarValue = 1;
+        private double glowBarValue;
 
         public double GlowBarValue
         {
@@ -61,7 +61,7 @@ public double GlowBarValue
             }
         }
 
-        private double healthBarValue = 1;
+        private double healthBarValue;
 
         public double HealthBarValue
         {

osu.Game/Screens/Play/HUD/FailingLayer.cs

@@ -29,6 +29,8 @@ public partial class FailingLayer : HealthDisplay
         /// </summary>
         public readonly Bindable<bool> ShowHealth = new Bindable<bool>();
 
+        protected override bool PlayInitialIncreaseAnimation => false;
+
         private const float max_alpha = 0.4f;
         private const int fade_time = 400;
         private const float gradient_size = 0.2f;

osu.Game/Screens/Play/HUD/HealthDisplay.cs

@@ -6,7 +6,9 @@
 using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Threading;
 using osu.Game.Rulesets.Judgements;
+using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Rulesets.UI;
 
@@ -23,12 +25,18 @@ public abstract partial class HealthDisplay : CompositeDrawable
         [Resolved]
         protected HealthProcessor HealthProcessor { get; private set; } = null!;
 
-        public Bindable<double> Current { get; } = new BindableDouble(1)
+        protected virtual bool PlayInitialIncreaseAnimation => true;
+
+        public Bindable<double> Current { get; } = new BindableDouble
         {
             MinValue = 0,
             MaxValue = 1
         };
 
+        private BindableNumber<double> health = null!;
+
+        private ScheduledDelegate? initialIncrease;
+
         /// <summary>
         /// Triggered when a <see cref="Judgement"/> is a successful hit, signaling the health display to perform a flash animation (if designed to do so).
         /// </summary>
@@ -52,14 +60,56 @@ protected override void LoadComplete()
         {
             base.LoadComplete();
 
-            Current.BindTo(HealthProcessor.Health);
             HealthProcessor.NewJudgement += onNewJudgement;
 
+            // Don't bind directly so we can animate the startup procedure.
+            health = HealthProcessor.Health.GetBoundCopy();
+            health.BindValueChanged(h =>
+            {
+                finishInitialAnimation();
+                Current.Value = h.NewValue;
+            });
+
             if (hudOverlay != null)
                 showHealthBar.BindTo(hudOverlay.ShowHealthBar);
 
             // this probably shouldn't be operating on `this.`
             showHealthBar.BindValueChanged(healthBar => this.FadeTo(healthBar.NewValue ? 1 : 0, HUDOverlay.FADE_DURATION, HUDOverlay.FADE_EASING), true);
+
+            if (PlayInitialIncreaseAnimation)
+                startInitialAnimation();
+            else
+                Current.Value = 1;
+        }
+
+        private void startInitialAnimation()
+        {
+            // TODO: this should run in gameplay time, including showing a larger increase when skipping.
+            // TODO: it should also start increasing relative to the first hitobject.
+            const double increase_delay = 150;
+
+            initialIncrease = Scheduler.AddDelayed(() =>
+            {
+                double newValue = Current.Value + 0.05f;
+                this.TransformBindableTo(Current, newValue, increase_delay);
+                Flash(new JudgementResult(new HitObject(), new Judgement()));
+
+                if (newValue >= 1)
+                    finishInitialAnimation();
+            }, increase_delay, true);
+        }
+
+        private void finishInitialAnimation()
+        {
+            initialIncrease?.Cancel();
+            initialIncrease = null;
+
+            // aside from the repeating `initialIncrease` scheduled task,
+            // there may also be a `Current` transform in progress from that schedule.
+            // ensure it plays out fully, to prevent changes to `Current.Value` being discarded by the ongoing transform.
+            // and yes, this funky `targetMember` spec is seemingly the only way to do this
+            // (see: https://github.com/ppy/osu-framework/blob/fe2769171c6e26d1b6fdd6eb7ea8353162fe9065/osu.Framework/Graphics/Transforms/TransformBindable.cs#L21)
+            FinishTransforms(targetMember: $"{Current.GetHashCode()}.{nameof(Current.Value)}");
         }
 
         private void onNewJudgement(JudgementResult judgement)

osu.Game/Skinning/LegacyHealthDisplay.cs

@@ -66,6 +66,7 @@ private void load(ISkinSource source)
             marker.Current.BindTo(Current);
 
             maxFillWidth = fill.Width;
+            fill.Width = 0;
         }
 
         protected override void Update()