fix: Wipeout fill color respects BACKGROUND command override

Scene now carries bg_color / paper_bg_color fields (defaults match
previous hard-coded values). synced_hatch_models() reads these instead
of hard-coded constants, so Wipeout fills correctly use the custom
background when BACKGROUND <r> <g> <b> has been set.
BACKGROUND command syncs both DocumentTab.bg_color and scene.bg_color.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

src/app/commands.rs

@@ -41,8 +41,10 @@ impl H7CAD {
                 if args.first().map(|s| s.eq_ignore_ascii_case("RESET")).unwrap_or(false) {
                     if is_paper {
                         self.tabs[i].paper_bg_color = None;
+                        self.tabs[i].scene.paper_bg_color = [0.22, 0.24, 0.28, 1.0];
                     } else {
                         self.tabs[i].bg_color = None;
+                        self.tabs[i].scene.bg_color = [0.11, 0.11, 0.11, 1.0];
                     }
                     self.command_line.push_output("Background reset to default.");
                 } else if args.len() >= 3 {
@@ -51,8 +53,10 @@ impl H7CAD {
                     let b = args[2].parse::<u8>().unwrap_or(0) as f32 / 255.0;
                     if is_paper {
                         self.tabs[i].paper_bg_color = Some([r, g, b, 1.0]);
+                        self.tabs[i].scene.paper_bg_color = [r, g, b, 1.0];
                     } else {
                         self.tabs[i].bg_color = Some([r, g, b, 1.0]);
+                        self.tabs[i].scene.bg_color = [r, g, b, 1.0];
                     }
                     self.command_line
                         .push_output(&format!("Background: rgb({}, {}, {})", args[0], args[1], args[2]));

src/scene/mod.rs

@@ -69,6 +69,11 @@ pub struct Scene {
     /// `None` = paper space editing (PSPACE).  Only meaningful when
     /// `current_layout != "Model"`.
     pub active_viewport: Option<Handle>,
+    /// Custom model-space background fill color for Wipeout entities.
+    /// Set from the active tab's `bg_color`; defaults to dark grey.
+    pub bg_color: [f32; 4],
+    /// Custom paper-space background fill color for Wipeout entities.
+    pub paper_bg_color: [f32; 4],
 }
 
 impl Scene {
@@ -86,6 +91,8 @@ impl Scene {
             meshes: HashMap::new(),
             images: HashMap::new(),
             active_viewport: None,
+            bg_color: [0.11, 0.11, 0.11, 1.0],
+            paper_bg_color: [0.22, 0.24, 0.28, 1.0],
         }
     }
 
@@ -1216,9 +1223,9 @@ impl Scene {
         // they mask hatch fills drawn earlier in the same pass.
         // Wipeout fills are appended last so they render on top of other hatches.
         let bg_color: [f32; 4] = if self.current_layout == "Model" {
-            [0.11, 0.11, 0.11, 1.0]
+            self.bg_color
         } else {
-            [0.22, 0.24, 0.28, 1.0]
+            self.paper_bg_color
         };
         for entity in self.document.entities() {
             let EntityType::Wipeout(wo) = entity else { continue };