WIP count feature

src/scene/mod.rs

@@ -1930,6 +1930,15 @@ pub enum ViewportRefreshScope {
 /// Entity membership in document order, keyed by geometry epoch.
 type BlockMembers = (u64, HashMap<Handle, Vec<Handle>>);
 
+/// What count mode colours: see [`Scene::count_display`].
+#[derive(Debug, Clone, PartialEq, Default)]
+pub struct CountDisplay {
+    pub counted: HashSet<Handle>,
+    pub errors: HashSet<Handle>,
+    pub color: [f32; 4],
+    pub error_color: [f32; 4],
+}
+
 pub struct Scene {
     pub camera: Rc<RefCell<Camera>>,
     /// View saved immediately before the latest navigation operation. ZOOM
@@ -2018,6 +2027,10 @@ pub struct Scene {
     /// edited geometry stands out while the surrounding drawing stays visible
     /// for context. `None` = not editing. (#136)
     pub refedit_keep: Option<HashSet<Handle>>,
+    /// COUNT mode colours: counted references in COUNTCOLOR, overlapping
+    /// duplicates in COUNTERRORCOLOR, everything else faded. `None` outside
+    /// count mode.
+    pub count_display: Option<CountDisplay>,
     /// Entity drawn with the selection-highlight colour without being part
     /// of the real selection — used to preview a row in the cycling list box.
     pub hover_highlight: Option<Handle>,
@@ -2612,6 +2625,7 @@ impl Scene {
             preview_hidden: HashSet::default(),
             command_preview_hidden: HashSet::default(),
             refedit_keep: None,
+            count_display: None,
             hover_highlight: None,
             constraint_hover_highlights: HashSet::default(),
             constraint_hover_refs: Vec::new(),
@@ -4084,10 +4098,32 @@ impl Scene {
         self.bump_geometry_no_blocks();
     }
 
+    /// Enter / leave the COUNT colouring; a no-op when nothing changed.
+    pub fn set_count_display(&mut self, display: Option<CountDisplay>) {
+        if self.count_display == display {
+            return;
+        }
+        self.count_display = display;
+        self.bump_geometry_no_blocks();
+    }
+
     /// Fade the colours of wires that belong to entities outside the REFEDIT
     /// keep set (no-op when not editing). The geometry is untouched, so
-    /// hit-testing still works on faded entities.
+    /// hit-testing still works on faded entities. In count mode the counted
+    /// references and the duplicates take the count colours instead.
     fn apply_refedit_fade(&self, wires: &mut [WireModel], bg: [f32; 4]) {
+        if let Some(count) = &self.count_display {
+            for w in wires.iter_mut() {
+                let h = Self::handle_from_wire_name(&w.name);
+                w.color = match h {
+                    Some(h) if count.errors.contains(&h) => count.error_color,
+                    Some(h) if count.counted.contains(&h) => count.color,
+                    _ => crate::scene::cache::block_cache::fade_toward_bg(w.color, bg),
+                };
+                // Shared instance geometry keeps its own colour; draw these wires on their own.
+                w.render_instance = None;
+            }
+        }
         let Some(keep) = &self.refedit_keep else {
             return;
         };