From eea96e3e182bf2f0a643344d4384a086f5427ebc Mon Sep 17 00:00:00 2001
From: Rian8337 <52914632+Rian8337@users.noreply.github.com>
Date: Thu, 23 Jan 2025 01:42:29 +0800
Subject: [PATCH] Match slider snaking in speed and slider tail circle fade
 animation with osu!stable

---
 .../ccfit/zuev/osu/game/GameplaySlider.java   | 40 ++++++++++---------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/src/ru/nsu/ccfit/zuev/osu/game/GameplaySlider.java b/src/ru/nsu/ccfit/zuev/osu/game/GameplaySlider.java
index 0374e4f81..51726ce01 100644
--- a/src/ru/nsu/ccfit/zuev/osu/game/GameplaySlider.java
+++ b/src/ru/nsu/ccfit/zuev/osu/game/GameplaySlider.java
@@ -250,8 +250,12 @@ public void init(final GameObjectListener listener, final Scene scene,
         timePreempt = (float) beatmapSlider.timePreempt / 1000;
         float fadeInDuration = (float) beatmapSlider.timeFadeIn / 1000;
 
+        // When snaking in is enabled, the first repeat or tail needs to be delayed until the snaking completes.
+        float fadeInDelay = Config.isSnakingInSliders() ? timePreempt / 3 : 0;
+
         if (GameHelper.isHidden()) {
             float fadeOutDuration = timePreempt * (float) ModHidden.FADE_OUT_DURATION_MULTIPLIER;
+            float finalTailAlpha = (fadeInDuration - fadeInDelay) / fadeInDuration;
 
             headCirclePiece.registerEntityModifier(Modifiers.sequence(
                     Modifiers.fadeIn(fadeInDuration),
@@ -259,13 +263,18 @@ public void init(final GameObjectListener listener, final Scene scene,
             ));
 
             tailCirclePiece.registerEntityModifier(Modifiers.sequence(
-                    Modifiers.fadeIn(fadeInDuration),
-                    Modifiers.fadeOut(fadeOutDuration)
+                    Modifiers.delay(fadeInDelay),
+                    Modifiers.alpha(fadeInDuration - fadeInDelay, 0, finalTailAlpha),
+                    Modifiers.alpha(fadeOutDuration, finalTailAlpha, 0)
             ));
 
         } else {
             headCirclePiece.registerEntityModifier(Modifiers.fadeIn(fadeInDuration));
-            tailCirclePiece.registerEntityModifier(Modifiers.fadeIn(fadeInDuration));
+
+            tailCirclePiece.registerEntityModifier(Modifiers.sequence(
+                    Modifiers.delay(fadeInDelay),
+                    Modifiers.fadeIn(fadeInDuration)
+            ));
         }
 
         if (approachCircle.isVisible()) {
@@ -289,6 +298,11 @@ public void init(final GameObjectListener listener, final Scene scene,
                 endArrow.setPosition(pathEndPosition.x, pathEndPosition.y);
             }
 
+            endArrow.registerEntityModifier(Modifiers.sequence(
+                    Modifiers.delay(fadeInDelay),
+                    Modifiers.fadeIn(fadeInDuration)
+            ));
+
             scene.attachChild(endArrow, 0);
         }
         scene.attachChild(tailCirclePiece, 0);
@@ -771,17 +785,10 @@ public void update(final float dt) {
                 approachCircle.setAlpha(0);
             }
 
-            float percentage = (float) (1 + elapsedSpanTime / timePreempt);
-
-            if (percentage <= 0.5f) {
-                // Following core doing a very cute show animation ^_^"
-                percentage = Math.min(1, percentage * 2);
-
-                if (beatmapSlider.getSpanCount() > 1) {
-                    endArrow.setAlpha(percentage);
-                }
+            if (Config.isSnakingInSliders()) {
+                float percentage = FMath.clamp((float) (timePreempt + elapsedSpanTime) / (timePreempt / 3), 0, 1);
 
-                if (Config.isSnakingInSliders()) {
+                if (percentage < 1) {
                     if (superPath != null && sliderBody != null) {
                         float l = superPath.getMeasurer().maxLength() * percentage;
 
@@ -792,12 +799,7 @@ public void update(final float dt) {
 
                     tailCirclePiece.setPosition(position.x, position.y);
                     endArrow.setPosition(position.x, position.y);
-                }
-            } else if (percentage - dt / timePreempt <= 0.5f) {
-                if (beatmapSlider.getSpanCount() > 1) {
-                    endArrow.setAlpha(1);
-                }
-                if (Config.isSnakingInSliders()) {
+                } else {
                     if (!preStageFinish && superPath != null && sliderBody != null) {
                         sliderBody.setEndLength(superPath.getMeasurer().maxLength());
                         preStageFinish = true;