From ee3367d7c549acecb778c652365c290e3e186e5b Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Fri, 5 Feb 2021 16:59:13 +0900
Subject: [PATCH] Add classic slider ball tracking

---
 osu.Game.Rulesets.Osu/Mods/OsuModClassic.cs     | 17 ++++++++++++++++-
 .../Skinning/Default/SliderBall.cs              | 15 ++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/osu.Game.Rulesets.Osu/Mods/OsuModClassic.cs b/osu.Game.Rulesets.Osu/Mods/OsuModClassic.cs
index 6f41bcc0b0..df3afb7063 100644
--- a/osu.Game.Rulesets.Osu/Mods/OsuModClassic.cs
+++ b/osu.Game.Rulesets.Osu/Mods/OsuModClassic.cs
@@ -1,19 +1,22 @@
 // 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.Collections.Generic;
 using System.Linq;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics.Sprites;
 using osu.Game.Configuration;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Osu.Objects;
+using osu.Game.Rulesets.Osu.Objects.Drawables;
 using osu.Game.Rulesets.Osu.UI;
 using osu.Game.Rulesets.UI;
 
 namespace osu.Game.Rulesets.Osu.Mods
 {
-    public class OsuModClassic : Mod, IApplicableToHitObject, IApplicableToDrawableRuleset<OsuHitObject>
+    public class OsuModClassic : Mod, IApplicableToHitObject, IApplicableToDrawableHitObjects, IApplicableToDrawableRuleset<OsuHitObject>
     {
         public override string Name => "Classic";
 
@@ -36,6 +39,9 @@ namespace osu.Game.Rulesets.Osu.Mods
         [SettingSource("Disable note lock lenience", "Applies note lock to the full hit window.")]
         public Bindable<bool> DisableLenientNoteLock { get; } = new BindableBool(true);
 
+        [SettingSource("Disable exact slider follow circle tracking", "Makes the slider follow circle track its final size at all times.")]
+        public Bindable<bool> DisableExactFollowCircleTracking { get; } = new BindableBool(true);
+
         public void ApplyToHitObject(HitObject hitObject)
         {
             switch (hitObject)
@@ -60,5 +66,14 @@ namespace osu.Game.Rulesets.Osu.Mods
             if (!DisableLenientNoteLock.Value)
                 osuRuleset.Playfield.HitPolicy = new ObjectOrderedHitPolicy();
         }
+
+        public void ApplyToDrawableHitObjects(IEnumerable<DrawableHitObject> drawables)
+        {
+            foreach (var obj in drawables)
+            {
+                if (obj is DrawableSlider slider)
+                    slider.Ball.TrackVisualSize = !DisableExactFollowCircleTracking.Value;
+            }
+        }
     }
 }
diff --git a/osu.Game.Rulesets.Osu/Skinning/Default/SliderBall.cs b/osu.Game.Rulesets.Osu/Skinning/Default/SliderBall.cs
index a96beb66d4..da3debbd42 100644
--- a/osu.Game.Rulesets.Osu/Skinning/Default/SliderBall.cs
+++ b/osu.Game.Rulesets.Osu/Skinning/Default/SliderBall.cs
@@ -31,6 +31,12 @@ namespace osu.Game.Rulesets.Osu.Skinning.Default
             set => ball.Colour = value;
         }
 
+        /// <summary>
+        /// Whether to track accurately to the visual size of this <see cref="SliderBall"/>.
+        /// If <c>false</c>, tracking will be performed at the final scale at all times.
+        /// </summary>
+        public bool TrackVisualSize = true;
+
         private readonly Drawable followCircle;
         private readonly DrawableSlider drawableSlider;
         private readonly Drawable ball;
@@ -94,7 +100,14 @@ namespace osu.Game.Rulesets.Osu.Skinning.Default
 
                 tracking = value;
 
-                followCircle.ScaleTo(tracking ? 2.4f : 1f, 300, Easing.OutQuint);
+                if (TrackVisualSize)
+                    followCircle.ScaleTo(tracking ? 2.4f : 1f, 300, Easing.OutQuint);
+                else
+                {
+                    // We need to always be tracking the final size, at both endpoints. For now, this is achieved by removing the scale duration.
+                    followCircle.ScaleTo(tracking ? 2.4f : 1f);
+                }
+
                 followCircle.FadeTo(tracking ? 1f : 0, 300, Easing.OutQuint);
             }
         }