"CursorTrailRotate" does not work even if enabled in skin.ini

[renyoko]

Type

Cosmetic

Bug description

When the skin.ini setting ‘CursorTrailRotate’ is enabled, the cursortrail rotates in stable, but not in lazer.
There is a possibility that this is the intended behaviour, but I was curious.

Here is a skin where you can see the behaviour (blue line is cursor and red line is cursortrail, both ‘CursorRotate’ and ‘CursorTrailRotate’ are enabled for clarity)

Screenshots or videos

stable:
https://github.com/user-attachments/assets/1a07c58b-8e54-4e90-aec2-1dc0ea52917b

lazer:
https://github.com/user-attachments/assets/04172685-a634-4d4f-85f9-d36ee69fdbd2

Version

2025.101.0-lazer

Logs

compressed-logs.zip

[peppy]

This will require shader changes. Maybe @EVAST9919 can pick it up?

https://osu.ppy.sh/wiki/en/Skinning/skin.ini

CursorTrailRotate:
Question: Should the cursor trail sprite rotate constantly?
Values: 0 or 1
Default: 1

Here's a starting point:

diff --git a/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyCursorTrail.cs b/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyCursorTrail.cs
index ca0002d8c0..45ea485963 100644
--- a/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyCursorTrail.cs
+++ b/osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyCursorTrail.cs
@@ -24,6 +24,7 @@ public partial class LegacyCursorTrail : CursorTrail
         private IBindable<float> cursorSize = null!;
 
         private Vector2? currentPosition;
+        private bool spin;
 
         public LegacyCursorTrail(ISkin skin)
         {
@@ -34,6 +35,7 @@ public LegacyCursorTrail(ISkin skin)
         private void load(OsuConfigManager config, ISkinSource skinSource)
         {
             cursorSize = config.GetBindable<float>(OsuSetting.GameplayCursorSize).GetBoundCopy();
+            spin = skin.GetConfig<OsuSkinConfiguration, bool>(OsuSkinConfiguration.CursorTrailRotate)?.Value ?? true;
 
             Texture = skin.GetTexture("cursortrail");
 
diff --git a/osu.Game.Rulesets.Osu/Skinning/OsuSkinConfiguration.cs b/osu.Game.Rulesets.Osu/Skinning/OsuSkinConfiguration.cs
index 9685ab685d..81488ca1a3 100644
--- a/osu.Game.Rulesets.Osu/Skinning/OsuSkinConfiguration.cs
+++ b/osu.Game.Rulesets.Osu/Skinning/OsuSkinConfiguration.cs
@@ -9,6 +9,7 @@ public enum OsuSkinConfiguration
         CursorCentre,
         CursorExpand,
         CursorRotate,
+        CursorTrailRotate,
         HitCircleOverlayAboveNumber,
 
         // ReSharper disable once IdentifierTypo
diff --git a/osu.Game.Rulesets.Osu/UI/Cursor/CursorTrail.cs b/osu.Game.Rulesets.Osu/UI/Cursor/CursorTrail.cs
index 5132dc2859..5670d7213c 100644
--- a/osu.Game.Rulesets.Osu/UI/Cursor/CursorTrail.cs
+++ b/osu.Game.Rulesets.Osu/UI/Cursor/CursorTrail.cs
@@ -206,6 +206,7 @@ private void addPart(Vector2 localSpacePosition)
         private struct TrailPart
         {
             public Vector2 Position;
+            public float Rotation;
             public float Time;
             public Vector2 Scale;
             public long InvalidationID;
@@ -219,6 +220,7 @@ private class TrailDrawNode : DrawNode
             private Texture texture;
 
             private float time;
+            private float rotation;
             private float fadeExponent;
 
             private readonly TrailPart[] parts = new TrailPart[max_sprites];
@@ -239,6 +241,7 @@ public override void ApplyState()
                 texture = Source.texture;
                 time = Source.time;
                 fadeExponent = Source.FadeExponent;
+                rotation = Source.Rotation;
 
                 originPosition = Vector2.Zero;
 

[EVAST9919]

Not sure why we would need to change shader code. Can't we just compute rotated vertex positions in the draw node?

[peppy]

Possibly, it was a bit deep for me to setup in 5 minutes so I bailed 😅