Dim toggle channel panels via CanvasGroup alpha

Each channel panel (Albedo, Metallic+Smoothness, Occlusion, Emission)
gets a CanvasGroup whose alpha follows its toggle: 1.0 when enabled,
0.5 when disabled. Ensured at runtime in WirePanel (no prefab re-bake),
so both the prefab and code-gen paths behave identically. Panel_BrushSize
has no toggle and is left untouched.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/PaintHud.cs

@@ -161,6 +161,12 @@ public class PaintHud : MonoBehaviour
         WireToggle(panel, ToggleOcclusion, painter && painter.paintOcclusion, v => { if (painter) painter.paintOcclusion = v; });
         WireToggle(panel, ToggleEmission, painter && painter.paintEmission, v => { if (painter) painter.paintEmission = v; });
 
+        // Dim a channel panel to 0.5 alpha while its toggle is off, full alpha while on.
+        WirePanelFade(panel, PanelAlbedo, ToggleAlbedo);
+        WirePanelFade(panel, PanelMetallicSmoothness, ToggleMetallicSmoothness);
+        WirePanelFade(panel, PanelOcclusion, ToggleOcclusion);
+        WirePanelFade(panel, PanelEmission, ToggleEmission);
+
         WirePicker(panel, PickerAlbedo, painter ? painter.brushColor : Color.red,
             c => { if (painter) painter.brushColor = new Color(c.r, c.g, c.b, painter.brushColor.a); });
 
@@ -206,6 +212,26 @@ public class PaintHud : MonoBehaviour
         toggle.onValueChanged.AddListener(v => onChanged(v));
     }
 
+    /// <summary>
+    /// Ensures a <see cref="CanvasGroup"/> on the channel panel and drives its alpha from the toggle:
+    /// 1 while the channel is enabled, 0.5 while disabled. Call after <see cref="WireToggle"/> so the
+    /// initial alpha reflects the toggle's painter-synced state. The group stays interactive (default
+    /// interactable/blocksRaycasts), so a dimmed panel can still be clicked to re-enable its channel.
+    /// </summary>
+    private static void WirePanelFade(Transform root, string panelName, string toggleName)
+    {
+        var panel = FindDeep(root, panelName);
+        if (!panel) return;
+        var group = panel.GetComponent<CanvasGroup>();
+        if (!group) group = panel.gameObject.AddComponent<CanvasGroup>();
+
+        var toggle = Find<Toggle>(panel, toggleName);
+        if (!toggle) { group.alpha = 1f; return; }
+
+        group.alpha = toggle.isOn ? 1f : 0.5f;
+        toggle.onValueChanged.AddListener(v => group.alpha = v ? 1f : 0.5f);
+    }
+
     private static void WireSlider(Transform panel, string name, float value, Action<float> onChanged)
     {
         var cell = FindDeep(panel, name);