fix(display): regenerate existing solid isolines

Rebuild cached solid meshes for REGEN and apply Options ISOLINES changes once when the slider is released.

src/app/commands/display.rs

@@ -508,7 +508,18 @@ impl OpenCADStudio {
             // "modified" merely because tessellation caches were invalidated (C7).
             // REGENALL is functionally identical (C5).
             "REGEN" | "REGENALL" => {
-                self.tabs[i].scene.bump_geometry();
+                // Solid meshes carry the isoline count they were tessellated
+                // with: `add_entity_internal` and `update_entity` pass
+                // `header.isolines` into `tessellate_volume` and store the
+                // result. Bumping the geometry epoch clears the wire memo but
+                // never re-runs that, so changing ISOLINES left every existing
+                // solid showing the density it was born with, and REGEN — the
+                // command whose whole job is this — did not help.
+                //
+                // `populate_meshes_from_document` re-tessellates from the
+                // document and bumps the epoch itself, so it replaces the bump
+                // rather than adding to it.
+                self.tabs[i].scene.populate_meshes_from_document();
                 self.command_line.push_output(crate::t!("REGEN: regenerated model.").as_ref());
                 return Some(Task::none());
             }
@@ -1893,3 +1904,110 @@ mod tests {
         assert!(!app.tabs[i].dirty, "REGENALL must not dirty the document either");
     }
 }
+
+#[cfg(test)]
+mod regen_tests {
+    use crate::app::OpenCADStudio;
+
+    /// A solid's mesh carries the isoline count it was tessellated with:
+    /// `add_entity_internal` and `update_entity` pass `header.isolines` into
+    /// `tessellate_volume` and store the result. REGEN used to bump the
+    /// geometry epoch and stop, which clears the wire memo but leaves
+    /// `scene.meshes` exactly as it was — reported on #1123 as "REGEN should
+    /// fix this, but the isolines keep visible".
+    ///
+    /// Building ACIS geometry here would be out of proportion, so the mesh map
+    /// is seeded with a stale entry instead: REGEN must rebuild the map from
+    /// the document, and an entry belonging to no entity cannot survive that.
+    /// Bumping alone would leave it in place.
+    #[test]
+    fn regen_rebuilds_the_mesh_map_rather_than_only_bumping_the_epoch() {
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        let i = app.active_tab;
+
+        // An entry belonging to no entity. Rebuilding the map from the document
+        // drops it; bumping the geometry epoch leaves it exactly where it is,
+        // which is the whole difference this fix turns on.
+        let stale = acadrust::Handle::new(0xDEAD);
+        app.tabs[i].scene.meshes.insert(stale, stale_mesh());
+        let epoch_before = app.tabs[i].scene.geometry_epoch;
+
+        let _ = app.run_command_line("REGEN");
+
+        assert!(
+            !app.tabs[i].scene.meshes.contains_key(&stale),
+            "REGEN must rebuild the mesh map, not leave what was there",
+        );
+        assert_ne!(
+            app.tabs[i].scene.geometry_epoch, epoch_before,
+            "and it still has to bump the geometry epoch",
+        );
+    }
+
+    /// Dragging the isolines slider must not rebuild every solid's mesh on the
+    /// way — a drag emits a message per pixel, and the rebuild is the same work
+    /// REGEN does. It waits for the release, and only runs if the value moved.
+    #[test]
+    fn the_isolines_slider_rebuilds_once_on_release_and_not_while_dragging() {
+        use crate::app::Message;
+
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        let i = app.active_tab;
+
+        let seed = |app: &mut OpenCADStudio, i: usize| {
+            let stale = acadrust::Handle::new(0xBEEF);
+            app.tabs[i].scene.meshes.insert(stale, stale_mesh());
+            stale
+        };
+        let stale = seed(&mut app, i);
+
+        for value in [4i16, 3, 2, 1, 0] {
+            let _ = app.update(Message::IsolinesChanged(value));
+        }
+        assert!(
+            app.tabs[i].scene.meshes.contains_key(&stale),
+            "the drag itself must not rebuild the meshes",
+        );
+        assert_eq!(app.tabs[i].scene.document.header.isolines, 0);
+
+        let _ = app.update(Message::IsolinesReleased);
+        assert!(
+            !app.tabs[i].scene.meshes.contains_key(&stale),
+            "releasing after a change rebuilds them",
+        );
+
+        // A release with nothing changed since the last one is a click that
+        // moved nothing, and must not pay for a rebuild.
+        let stale = seed(&mut app, i);
+        let _ = app.update(Message::IsolinesChanged(0));
+        let _ = app.update(Message::IsolinesReleased);
+        assert!(
+            app.tabs[i].scene.meshes.contains_key(&stale),
+            "releasing without a change must rebuild nothing",
+        );
+    }
+
+    fn stale_mesh() -> crate::scene::model::mesh_model::MeshLodSet {
+        crate::scene::model::mesh_model::MeshLodSet {
+            lods: Vec::new(),
+            material: None,
+            face_materials: Default::default(),
+            visual_style: None,
+            complete: true,
+            edge_verts: Vec::new(),
+            edge_verts_low: Vec::new(),
+            curved_gens: Vec::new(),
+            metrics: Default::default(),
+            world_aabb: [0.0; 4],
+            z_aabb: [0.0; 2],
+            instance_source: None,
+            instance_transform: None,
+            instance_handle: None,
+            instance_color: None,
+            instance_aabb: None,
+        }
+    }
+}
+

src/app/mod.rs

@@ -517,6 +517,10 @@ pub(super) struct OpenCADStudio {
     crosshair_color: Option<[u8; 3]>,
     /// Editable Options buffer for the crosshair colour.
     crosshair_color_input: String,
+    /// Set while the isolines slider is being dragged with a value that
+    /// differs from the drawing's, so the costly mesh rebuild runs once on
+    /// release rather than on every pixel of the drag.
+    isolines_awaiting_regen: bool,
     /// Edit buffer for the SNAPANG field on the Options Drafting page. Kept
     /// separate from `snap_angle_deg` so a half-typed angle is not parsed.
     snap_angle_input: String,
@@ -2048,6 +2052,8 @@ pub enum Message {
     OpenFolder(String),
     /// Change isolines per surface in the current drawing (ISOLINES).
     IsolinesChanged(i16),
+    /// The isolines slider was released; rebuild the meshes if it moved.
+    IsolinesReleased,
     /// Toggle silhouette edges in the current drawing (DISPSILH).
     DispSilhChanged(bool),
     /// Change surface density U in the current drawing (SURFU).
@@ -3460,6 +3466,7 @@ impl OpenCADStudio {
             cursor_type: settings::CursorType::Crosshair,
             crosshair_color: None,
             crosshair_color_input: String::new(),
+            isolines_awaiting_regen: false,
             snap_angle_input: "0".to_string(),
             lineweight_display_scale: 100,
             isometric_drafting: false,

src/app/settings.rs

@@ -145,6 +145,27 @@ pub(crate) fn snaps_from_osmode(osmode: i32) -> (Vec<SnapType>, bool) {
     (modes, osmode & OSMODE_SUPPRESS == 0)
 }
 
+fn deserialize_options_tab<'de, D>(
+    deserializer: D,
+) -> Result<crate::ui::window::options::OptionsTab, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    use crate::ui::window::options::OptionsTab;
+    use serde::Deserialize;
+    let name = String::deserialize(deserializer).unwrap_or_default();
+    Ok(match name.as_str() {
+        "files" => OptionsTab::Files,
+        "open-and-save" => OptionsTab::OpenAndSave,
+        "display" => OptionsTab::Display,
+        "drafting" => OptionsTab::Drafting,
+        "modeling" => OptionsTab::Modeling,
+        "selection" => OptionsTab::Selection,
+        "user-preferences" => OptionsTab::UserPreferences,
+        _ => OptionsTab::General,
+    })
+}
+
 /// Render a drafting angle without a trailing `.0`, so `22.5` but `30`.
 ///
 /// The polar pop-up formats its presets the same way; both are showing the
@@ -183,6 +204,12 @@ pub struct UserSettings {
     /// all. 0 means no limit. The drawing header carries no slot for it.
     pub grip_object_limit: i32,
     /// Which Options page was showing when the dialog was last closed.
+    ///
+    /// Read leniently: `AppConfig::load` discards the *whole* file when any
+    /// field fails to parse, so a page name that no longer exists — a tab
+    /// renamed or merged away between versions — would silently reset every
+    /// setting the user has. An unknown name falls back to the first page.
+    #[serde(default, deserialize_with = "deserialize_options_tab")]
     pub options_tab: crate::ui::window::options::OptionsTab,
     /// Show the navigation cube (NAVVCUBE).
     pub show_viewcube: bool,
@@ -427,4 +454,29 @@ mod tests {
         let b: std::collections::HashSet<_> = back.into_iter().collect();
         assert_eq!(a, b);
     }
+
+    /// `AppConfig::load` throws the whole file away when any field fails to
+    /// parse, so a page name that no longer exists would quietly reset every
+    /// preference the user has. This branch removed the Drawing page, and
+    /// anyone who had it open when they last closed the dialog has that name
+    /// on disk.
+    #[test]
+    fn a_page_name_that_no_longer_exists_does_not_cost_the_other_settings() {
+        let json = r#"{
+            "settings": {
+                "options_tab": "drawing",
+                "pick_add": false,
+                "savetime_min": 42
+            }
+        }"#;
+        let cfg: crate::app::config::AppConfig =
+            serde_json::from_str(json).expect("an unknown page name must not fail the parse");
+        assert_eq!(
+            cfg.settings.options_tab,
+            crate::ui::window::options::OptionsTab::General,
+        );
+        assert!(!cfg.settings.pick_add, "the rest of the file must survive");
+        assert_eq!(cfg.settings.savetime_min, 42);
+    }
 }
+

src/app/update/file.rs

@@ -355,24 +355,37 @@ impl OpenCADStudio {
         }
     }
 
-    /// Write a tessellation-affecting header variable on the active drawing.
+    /// Write a header variable on the active drawing and mark it modified.
     ///
-    /// These decide how solids and surfaces are tessellated, so the geometry
-    /// has to be rebuilt for the change to appear — the same reason `LTSCALE`
-    /// bumps it. Marking the tab modified is what makes the new value reach
-    /// the file.
-    pub(in crate::app) fn set_drawing_tessellation_var(
+    /// Deliberately does no geometry work. The variables the Options pages
+    /// write differ in what they cost to apply, and treating them alike is
+    /// wrong in both directions: `DISPSILH` is read at render time and needs
+    /// nothing, `SURFU`/`SURFV`/`SURFTYPE` are inputs to PEDIT's smoothing and
+    /// need nothing until it runs, while `ISOLINES` is baked into solid meshes
+    /// at tessellation and needs more than a bump — see `regenerate_meshes`.
+    pub(in crate::app) fn set_drawing_var(
         &mut self,
         write: impl FnOnce(&mut acadrust::document::HeaderVariables),
     ) {
         let i = self.active_tab;
         if let Some(tab) = self.tabs.get_mut(i) {
             write(&mut tab.scene.document.header);
-            tab.scene.bump_geometry();
             tab.dirty = true;
         }
     }
 
+    /// Re-tessellate the active drawing's solids from the document.
+    ///
+    /// What REGEN does, and the only thing that makes a changed `ISOLINES`
+    /// reach solids that already exist. Costly on a solid-heavy drawing, so
+    /// callers driven by a slider run it when the drag ends, not per tick.
+    pub(in crate::app) fn regenerate_meshes(&mut self) {
+        let i = self.active_tab;
+        if let Some(tab) = self.tabs.get_mut(i) {
+            tab.scene.populate_meshes_from_document();
+        }
+    }
+
     /// Rebuild text geometry in every open drawing.
     ///
     /// `TEXTFILL` is a process-global, so a change to it invalidates the text

src/app/update/mod.rs

@@ -6305,54 +6305,73 @@ impl OpenCADStudio {
                 Task::none()
             }
 
-            // The five below are drawing variables: they go into the header of
-            // the active drawing and mark it modified, exactly as SETVAR does.
-            // The four that feed solid tessellation also bump the geometry, or
-            // the change is invisible until an unrelated edit rebuilds it.
+            // Drawing variables: they go into the header of the active
+            // drawing and mark it modified, as SETVAR does. What each one
+            // costs to apply differs, so they are not treated alike.
+            //
+            // ISOLINES is baked into a solid's mesh when it is tessellated, so
+            // an existing solid keeps the density it was born with until the
+            // meshes are rebuilt. That is expensive, and a slider emits on
+            // every pixel of a drag, so the rebuild waits for the release —
+            // and only happens if the value actually moved.
             Message::IsolinesChanged(value) => {
-                self.set_drawing_tessellation_var(|header| header.isolines = value.max(0));
-                Task::none()
-            }
-
-            Message::DispSilhChanged(on) => {
-                self.set_drawing_tessellation_var(|header| header.display_silhouette = on);
-                Task::none()
-            }
-
-            Message::SurfaceUChanged(value) => {
-                self.set_drawing_tessellation_var(|header| {
-                    header.surface_u_density = value.clamp(0, 200)
-                });
-                Task::none()
-            }
-
-            Message::SurfaceVChanged(value) => {
-                self.set_drawing_tessellation_var(|header| {
-                    header.surface_v_density = value.clamp(0, 200)
-                });
-                Task::none()
-            }
-
-            Message::SurfaceTypeChanged(value) => {
-                self.set_drawing_tessellation_var(|header| header.surface_type = value);
-                Task::none()
-            }
-
-            Message::SolidHistChanged(record) => {
-                let i = self.active_tab;
-                if let Some(tab) = self.tabs.get_mut(i) {
-                    tab.scene.document.header.record_solid_history = record;
-                    tab.dirty = true;
+                let value = value.max(0);
+                let changed = self
+                    .tabs
+                    .get(self.active_tab)
+                    .is_some_and(|tab| tab.scene.document.header.isolines != value);
+                if changed {
+                    self.set_drawing_var(|header| header.isolines = value);
+                    self.isolines_awaiting_regen = true;
                 }
                 Task::none()
             }
 
+            Message::IsolinesReleased => {
+                if std::mem::take(&mut self.isolines_awaiting_regen) {
+                    self.regenerate_meshes();
+                }
+                Task::none()
+            }
+
+            // Read at render time, so nothing has to be rebuilt for it.
+            Message::DispSilhChanged(on) => {
+                self.set_drawing_var(|header| header.display_silhouette = on);
+                Task::none()
+            }
+
+            // Inputs to PEDIT's mesh smoothing; they change nothing until it
+            // runs, so writing the header is the whole job.
+            Message::SurfaceUChanged(value) => {
+                self.set_drawing_var(|header| header.surface_u_density = value.clamp(0, 200));
+                Task::none()
+            }
+
+            Message::SurfaceVChanged(value) => {
+                self.set_drawing_var(|header| header.surface_v_density = value.clamp(0, 200));
+                Task::none()
+            }
+
+            Message::SurfaceTypeChanged(value) => {
+                self.set_drawing_var(|header| header.surface_type = value);
+                Task::none()
+            }
+
+            // Whether history is recorded from now on; nothing to redraw.
+            Message::SolidHistChanged(record) => {
+                self.set_drawing_var(|header| header.record_solid_history = record);
+                Task::none()
+            }
+
+            // Read while building geometry, so this one does bump — the same
+            // thing the SHOWHIST command does.
             Message::ShowHistChanged(mode) => {
+                self.set_drawing_var(|header| {
+                    header.show_solid_history = mode.clamp(0, 2)
+                });
                 let i = self.active_tab;
                 if let Some(tab) = self.tabs.get_mut(i) {
-                    tab.scene.document.header.show_solid_history = mode.clamp(0, 2);
                     tab.scene.bump_geometry();
-                    tab.dirty = true;
                 }
                 Task::none()
             }

src/ui/window/options.rs

@@ -32,7 +32,6 @@ pub enum OptionsTab {
     Modeling,
     Selection,
     UserPreferences,
-    Drawing,
 }
 
 /// Application preferences the dialog reads that are plain scalars on the app.
@@ -1077,29 +1076,7 @@ pub fn view_window<'a>(
     .spacing(0)
     .width(sizing.width);
 
-    let drawing = column![
-        text(crate::t!("Block Edit")).size(15),
-        Space::new().height(10),
-        row![
-            iced::widget::checkbox(double_click_block_refedit)
-                .on_toggle(Message::DoubleClickBlockRefeditChanged)
-                .size(15),
-            text(crate::t!("Double-click to edit block in-place (REFEDIT)")).size(12),
-        ]
-        .spacing(8)
-        .align_y(iced::Center),
-        Space::new().height(18),
-        row![
-            iced::widget::checkbox(double_click_block_attedit)
-                .on_toggle(Message::DoubleClickBlockAtteditChanged)
-                .size(15),
-            text(crate::t!("Double-click attributed blocks to edit attributes (ATTEDIT)")).size(12),
-        ]
-        .spacing(8)
-        .align_y(iced::Center),
-    ]
-    .spacing(0)
-    .width(sizing.width);
+
 
 
     // ANNOAUTOSCALE's magnitude decides which objects a newly added scale
@@ -1225,6 +1202,26 @@ pub fn view_window<'a>(
         .size(11)
         .width(sizing.width),
         Space::new().height(24),
+        text(crate::t!("Block Edit")).size(15),
+        Space::new().height(10),
+        row![
+            iced::widget::checkbox(double_click_block_refedit)
+                .on_toggle(Message::DoubleClickBlockRefeditChanged)
+                .size(15),
+            text(crate::t!("Double-click to edit block in-place (REFEDIT)")).size(12),
+        ]
+        .spacing(8)
+        .align_y(iced::Center),
+        Space::new().height(18),
+        row![
+            iced::widget::checkbox(double_click_block_attedit)
+                .on_toggle(Message::DoubleClickBlockAtteditChanged)
+                .size(15),
+            text(crate::t!("Double-click attributed blocks to edit attributes (ATTEDIT)")).size(12),
+        ]
+        .spacing(8)
+        .align_y(iced::Center),
+        Space::new().height(24),
         text(crate::t!("Drawing Units")).size(15),
         Space::new().height(10),
         row![
@@ -1394,12 +1391,16 @@ pub fn view_window<'a>(
             .push(
                 row![
                     text(crate::t!("Isolines per surface")).size(12).width(150),
+                    // Rebuilding every solid's mesh is what makes a new
+                    // isoline count reach solids that already exist, and it is
+                    // far too costly to do on each pixel of a drag.
                     slider(
                         0..=64,
                         drawing_prefs.isolines.clamp(0, 64),
                         Message::IsolinesChanged,
                     )
                     .step(1i16)
+                    .on_release(Message::IsolinesReleased)
                     .width(Fill),
                     text(drawing_prefs.isolines.clamp(0, 64).to_string())
                         .size(11)
@@ -1565,7 +1566,6 @@ pub fn view_window<'a>(
         OptionsTab::Drafting => drafting.into(),
         OptionsTab::Modeling => modeling.into(),
         OptionsTab::UserPreferences => user_prefs.into(),
-        OptionsTab::Drawing => drawing.into(),
     };
 
     // A vertical rail rather than a horizontal strip: the tab names are
@@ -1588,7 +1588,6 @@ pub fn view_window<'a>(
         tab_button(crate::t!("3D Modeling"), OptionsTab::Modeling),
         tab_button(crate::t!("Selection"), OptionsTab::Selection),
         tab_button(crate::t!("User Preferences"), OptionsTab::UserPreferences),
-        tab_button(crate::t!("Drawing"), OptionsTab::Drawing),
     ]
     .spacing(2)
     .width(iced::Length::Fixed(TAB_RAIL_WIDTH));