Add opacity setting

osu.Game.Rulesets.Mania/UI/ManiaTouchInputOverlay.cs

@@ -16,7 +16,7 @@ namespace osu.Game.Rulesets.Mania.UI
 {
     public partial class ManiaTouchInputOverlay : CompositeDrawable, ISerialisableDrawable
     {
-        [SettingSource("Spacing", "The spacing between input receptors.")]
+        [SettingSource("Spacing", "The spacing between receptors.")]
         public BindableFloat Spacing { get; } = new BindableFloat(10)
         {
             Precision = 1,
@@ -24,6 +24,14 @@ namespace osu.Game.Rulesets.Mania.UI
             MaxValue = 100,
         };
 
+        [SettingSource("Opacity", "The receptor opacity.")]
+        public BindableFloat Opacity { get; } = new BindableFloat(1)
+        {
+            Precision = 0.1f,
+            MinValue = 0,
+            MaxValue = 1
+        };
+
         [Resolved]
         private ManiaPlayfield playfield { get; set; } = null!;
 
@@ -68,6 +76,12 @@ namespace osu.Game.Rulesets.Mania.UI
             };
         }
 
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+            Opacity.BindValueChanged(o => Alpha = o.NewValue, true);
+        }
+
         public bool UsesFixedAnchor { get; set; }
 
         public partial class InputReceptor : CompositeDrawable