From c1ac57e70fc05e11e6d085f2829eef31d524328e Mon Sep 17 00:00:00 2001
From: Lucas A <game4allyt@gmail.com>
Date: Thu, 26 Mar 2020 12:14:44 +0100
Subject: [PATCH] Add back visual tests and add easing to alpha fade.

---
 .../Visual/Gameplay/TestSceneFailingLayer.cs  | 31 +++++++++++++++++++
 osu.Game/Screens/Play/HUD/FailingLayer.cs     |  7 ++++-
 2 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 osu.Game.Tests/Visual/Gameplay/TestSceneFailingLayer.cs

diff --git a/osu.Game.Tests/Visual/Gameplay/TestSceneFailingLayer.cs b/osu.Game.Tests/Visual/Gameplay/TestSceneFailingLayer.cs
new file mode 100644
index 0000000000..3016890ade
--- /dev/null
+++ b/osu.Game.Tests/Visual/Gameplay/TestSceneFailingLayer.cs
@@ -0,0 +1,31 @@
+// 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 NUnit.Framework;
+using osu.Game.Screens.Play.HUD;
+
+namespace osu.Game.Tests.Visual.Gameplay
+{
+    public class TestSceneFailingLayer : OsuTestScene
+    {
+        private readonly FailingLayer layer;
+
+        public TestSceneFailingLayer()
+        {
+            Child = layer = new FailingLayer();
+        }
+
+        [Test]
+        public void TestLayerFading()
+        {
+            AddSliderStep("current health", 0.0, 1.0, 1.0, val =>
+            {
+                layer.Current.Value = val;
+            });
+
+            AddStep("set health to 0.10", () => layer.Current.Value = 0.10);
+            AddWaitStep("wait for fade to finish", 5);
+            AddStep("set health to 1", () => layer.Current.Value = 1f);
+        }
+    }
+}
diff --git a/osu.Game/Screens/Play/HUD/FailingLayer.cs b/osu.Game/Screens/Play/HUD/FailingLayer.cs
index 5f4037c14d..97d2458674 100644
--- a/osu.Game/Screens/Play/HUD/FailingLayer.cs
+++ b/osu.Game/Screens/Play/HUD/FailingLayer.cs
@@ -5,6 +5,7 @@ using System;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Shapes;
+using osu.Framework.Utils;
 using osu.Game.Graphics;
 
 namespace osu.Game.Screens.Play.HUD
@@ -16,6 +17,8 @@ namespace osu.Game.Screens.Play.HUD
     {
         private const float max_alpha = 0.4f;
 
+        private const int fade_time = 400;
+
         private readonly Box box;
 
         /// <summary>
@@ -41,7 +44,9 @@ namespace osu.Game.Screens.Play.HUD
 
         protected override void Update()
         {
-            box.Alpha = (float)Math.Clamp(max_alpha * (1 - Current.Value / LowHealthThreshold), 0, max_alpha);
+            box.Alpha = (float)Interpolation.ValueAt(Math.Clamp(Clock.ElapsedFrameTime, 0, fade_time), box.Alpha,
+                Math.Clamp(max_alpha * (1 - Current.Value / LowHealthThreshold), 0, max_alpha), 0, fade_time, Easing.Out);
+
             base.Update();
         }
     }