From 5c13c443ff79af12849311737f99ab705b6211ff Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Thu, 20 Oct 2022 23:08:18 +0900
Subject: [PATCH] Fix incorrect fallback logic

Regressed when attempting to share implementation of binary search.
---
 osu.Game/Beatmaps/ControlPoints/ControlPointInfo.cs    |  2 +-
 .../Scrolling/Algorithms/OverlappingScrollAlgorithm.cs | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/osu.Game/Beatmaps/ControlPoints/ControlPointInfo.cs b/osu.Game/Beatmaps/ControlPoints/ControlPointInfo.cs
index 9186685f0c..422e306450 100644
--- a/osu.Game/Beatmaps/ControlPoints/ControlPointInfo.cs
+++ b/osu.Game/Beatmaps/ControlPoints/ControlPointInfo.cs
@@ -207,7 +207,7 @@ namespace osu.Game.Beatmaps.ControlPoints
         /// </summary>
         /// <param name="list">The list to search.</param>
         /// <param name="time">The time to find the control point at.</param>
-        /// <returns>The active control point at <paramref name="time"/>.</returns>
+        /// <returns>The active control point at <paramref name="time"/>. Will return <c>null</c> if there are no control points, or if the time is before the first control point.</returns>
         public static T BinarySearch<T>(IReadOnlyList<T> list, double time)
             where T : class, IControlPoint
         {
diff --git a/osu.Game/Rulesets/UI/Scrolling/Algorithms/OverlappingScrollAlgorithm.cs b/osu.Game/Rulesets/UI/Scrolling/Algorithms/OverlappingScrollAlgorithm.cs
index 00bc7453d8..54079c7895 100644
--- a/osu.Game/Rulesets/UI/Scrolling/Algorithms/OverlappingScrollAlgorithm.cs
+++ b/osu.Game/Rulesets/UI/Scrolling/Algorithms/OverlappingScrollAlgorithm.cs
@@ -4,6 +4,7 @@
 #nullable disable
 
 using System;
+using System.Linq;
 using osu.Framework.Lists;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Rulesets.Timing;
@@ -73,6 +74,13 @@ namespace osu.Game.Rulesets.UI.Scrolling.Algorithms
         /// </summary>
         /// <param name="time">The time which the <see cref="MultiplierControlPoint"/> should affect.</param>
         /// <returns>The <see cref="MultiplierControlPoint"/>.</returns>
-        private MultiplierControlPoint controlPointAt(double time) => ControlPointInfo.BinarySearch(controlPoints, time) ?? new MultiplierControlPoint(double.NegativeInfinity);
+        private MultiplierControlPoint controlPointAt(double time)
+        {
+            return ControlPointInfo.BinarySearch(controlPoints, time)
+                   // The standard binary search will fail if there's no control points, or if the time is before the first.
+                   // For this method, we want to use the first control point in the latter case.
+                   ?? controlPoints.FirstOrDefault()
+                   ?? new MultiplierControlPoint(double.NegativeInfinity);
+        }
     }
 }