From 62bcb6284232833fbec4f30a8f79bfa635771ddf Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Fri, 29 Sep 2023 16:44:04 +0900
Subject: [PATCH] Document remaining pieces of `LastTick` and add back legacy
 prefix for generation flow

---
 .../Beatmaps/SliderEventGenerationTest.cs         |  4 ++--
 osu.Game/Rulesets/Objects/SliderEventGenerator.cs | 15 ++++++++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/osu.Game.Tests/Beatmaps/SliderEventGenerationTest.cs b/osu.Game.Tests/Beatmaps/SliderEventGenerationTest.cs
index 37a91c8611..c7cf3fe956 100644
--- a/osu.Game.Tests/Beatmaps/SliderEventGenerationTest.cs
+++ b/osu.Game.Tests/Beatmaps/SliderEventGenerationTest.cs
@@ -87,8 +87,8 @@ namespace osu.Game.Tests.Beatmaps
         {
             var events = SliderEventGenerator.Generate(start_time, span_duration, 1, span_duration / 2, span_duration, 1).ToArray();
 
-            Assert.That(events[2].Type, Is.EqualTo(SliderEventType.LastTick));
-            Assert.That(events[2].Time, Is.EqualTo(span_duration + SliderEventGenerator.LAST_TICK_OFFSET));
+            Assert.That(events[2].Type, Is.EqualTo(SliderEventType.LegacyLastTick));
+            Assert.That(events[2].Time, Is.EqualTo(span_duration + SliderEventGenerator.TAIL_LENIENCY));
         }
 
         [Test]
diff --git a/osu.Game/Rulesets/Objects/SliderEventGenerator.cs b/osu.Game/Rulesets/Objects/SliderEventGenerator.cs
index b3477a5fde..42c422a637 100644
--- a/osu.Game/Rulesets/Objects/SliderEventGenerator.cs
+++ b/osu.Game/Rulesets/Objects/SliderEventGenerator.cs
@@ -16,8 +16,12 @@ namespace osu.Game.Rulesets.Objects
         /// until the true end of the slider. This very small amount of leniency makes it easier to jump away from fast sliders to the next hit object.
         ///
         /// After discussion on how this should be handled going forward, players have unanimously stated that this lenience should remain in some way.
+        /// These days, this is implemented in the drawable implementation of Slider in the osu! ruleset.
+        ///
+        /// We need to keep the <see cref="SliderEventType.LegacyLastTick"/> *only* for osu!catch conversion, which relies on it to generate tiny ticks
+        /// correctly.
         /// </summary>
-        public const double LAST_TICK_OFFSET = -36;
+        public const double TAIL_LENIENCY = -36;
 
         public static IEnumerable<SliderEventDescriptor> Generate(double startTime, double spanDuration, double velocity, double tickDistance, double totalDistance, int spanCount,
                                                                   CancellationToken cancellationToken = default)
@@ -84,14 +88,14 @@ namespace osu.Game.Rulesets.Objects
 
             int finalSpanIndex = spanCount - 1;
             double finalSpanStartTime = startTime + finalSpanIndex * spanDuration;
-            double finalSpanEndTime = Math.Max(startTime + totalDuration / 2, (finalSpanStartTime + spanDuration) + LAST_TICK_OFFSET);
+            double finalSpanEndTime = Math.Max(startTime + totalDuration / 2, (finalSpanStartTime + spanDuration) + TAIL_LENIENCY);
             double finalProgress = (finalSpanEndTime - finalSpanStartTime) / spanDuration;
 
             if (spanCount % 2 == 0) finalProgress = 1 - finalProgress;
 
             yield return new SliderEventDescriptor
             {
-                Type = SliderEventType.LastTick,
+                Type = SliderEventType.LegacyLastTick,
                 SpanIndex = finalSpanIndex,
                 SpanStartTime = finalSpanStartTime,
                 Time = finalSpanEndTime,
@@ -183,9 +187,10 @@ namespace osu.Game.Rulesets.Objects
         Tick,
 
         /// <summary>
-        /// Occurs just before the tail. See <see cref="SliderEventGenerator.LAST_TICK_OFFSET"/>.
+        /// Occurs just before the tail. See <see cref="SliderEventGenerator.TAIL_LENIENCY"/>.
+        /// Should generally be ignored.
         /// </summary>
-        LastTick,
+        LegacyLastTick,
         Head,
         Tail,
         Repeat