Preferences ▸ Graphics ▸ Display quality (Coarse/Normal/Fine/Ultra) (#1287) (#1319)

* Preferences ▸ Graphics ▸ Display quality: Coarse, Normal, Fine, Ultra (#1287)

A viewing preference that sets how finely the viewport tessellates curved faces and edges:
chord tolerance relative to each body's size (3e-3, 1e-3, 3e-4, 1e-4) and the most a facet may
turn (30, 20, 12, 7 degrees). Normal is the tolerance the viewport has always used.

Bodies keep a display plan per level, so switching is a re-plan the first time and instant
after; the reference mesh the model reads (picks, holes, measuring) and exports are unchanged.
Away from Normal the model scene builds edges, and faces on the CPU path, from the plan at that
level, so silhouettes and edges get finer with the faces and a highlight still lies on the
displayed triangles.

The preference is saved with the others, set over the control channel (`ui.prefs`
`display_quality`), labelled in en/de/ja/ko/zh. `solidcraft-cli bench-open --display LEVEL
[--edit NAME EXPR]` times the plans at a level and after a parameter edit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Highlighted edges follow the display quality too

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/ui-egui/src/prefs.rs

@@ -248,6 +248,9 @@ pub struct Prefs {
     pub space_mouse_speed: f32,
     /// Anti-aliasing samples (applies on restart).
     pub msaa: u32,
+    /// How finely the viewport tessellates curved faces and edges: `coarse`, `normal`, `fine` or
+    /// `ultra` (#1287). Only the display plan the viewport draws; never the design or exports.
+    pub display_quality: String,
     /// Decimals shown for lengths and angles.
     pub length_decimals: u8,
     pub angle_decimals: u8,
@@ -327,6 +330,7 @@ impl Default for Prefs {
             space_mouse_enabled: true,
             space_mouse_speed: 1.0,
             msaa: 4,
+            display_quality: "normal".into(),
             length_decimals: 2,
             angle_decimals: 1,
             theme: "dark".into(),
@@ -467,6 +471,7 @@ fn defaults(app: &mut SolveApp, page: usize) {
         PAGE_GRAPHICS => {
             let msaa = p.msaa != d.msaa;
             p.msaa = d.msaa;
+            p.display_quality = d.display_quality;
             p.color_vision = d.color_vision;
             app.ui.visual_style = 0;
             app.ui.show_grid = true;
@@ -484,6 +489,10 @@ fn defaults(app: &mut SolveApp, page: usize) {
 /// Settings that follow the preferences every frame: the theme when it follows the system, and
 /// the interface scale.
 pub fn apply(app: &mut SolveApp, ctx: &egui::Context) {
+    // The viewport's display quality (an unknown saved value draws at Normal).
+    solidcraft_engine::doc::display_quality::set_current(
+        solidcraft_engine::doc::display_quality::DisplayQuality::parse(&app.preferences.display_quality).unwrap_or_default(),
+    );
     // The view's up axis follows the preference (set in the dialog, by ui.prefs or loaded).
     if app.prefs_window.applied_up.as_deref() != Some(app.preferences.up_axis.as_str()) {
         up_axis_changed(app);
@@ -1094,6 +1103,21 @@ fn page(app: &mut SolveApp, ui: &mut egui::Ui, t: &Tokens) {
             });
             ui.end_row();
             note(ui, app.tr("settings.msaa_applies_on_restart"));
+            ui.label(app.tr("ui.display_quality"));
+            {
+                use solidcraft_engine::doc::display_quality::DisplayQuality;
+                let label = |q: DisplayQuality| crate::i18n::tr(&format!("ui.display_quality_{}", q.id())).to_string();
+                let current = DisplayQuality::parse(&app.preferences.display_quality).unwrap_or_default();
+                egui::ComboBox::from_id_salt("pref_display_quality").selected_text(label(current)).show_ui(ui, |ui| {
+                    for q in DisplayQuality::ALL {
+                        if ui.selectable_label(q == current, label(q)).clicked() {
+                            app.preferences.display_quality = q.id().to_string();
+                        }
+                    }
+                });
+            }
+            ui.end_row();
+            note(ui, app.tr("settings.display_quality_note"));
             ui.label(crate::i18n::tr_label("Renderer"));
             ui.label(match (&app.viewport.gpu, &app.help.gpu) {
                 (Some(_), Some(g)) => format!("GPU: {g}"),
@@ -1305,6 +1329,9 @@ pub fn set(app: &mut SolveApp, p: &serde_json::Value) -> Result<serde_json::Valu
     if !(0.5..=2.5).contains(&new.ui_scale) || !(0.25..=4.0).contains(&new.look_at_speed) {
         return Err("`ui_scale` must be 0.5…2.5 and `look_at_speed` 0.25…4".into());
     }
+    if solidcraft_engine::doc::display_quality::DisplayQuality::parse(&new.display_quality).is_none() {
+        return Err("`display_quality` must be coarse, normal, fine or ultra".into());
+    }
     if MiddleDoubleClick::parse(&new.middle_double_click).is_none() {
         return Err("`middle_double_click` must be home, fit or off".into());
     }
@@ -1325,6 +1352,22 @@ pub fn set(app: &mut SolveApp, p: &serde_json::Value) -> Result<serde_json::Valu
 
 #[cfg(test)]
 mod tests {
+    /// Display quality (#1287) is a preference like any other: set by name, checked, saved with
+    /// the others, back to Normal with Restore Defaults.
+    #[test]
+    fn display_quality_is_set_checked_and_restored() {
+        use serde_json::json;
+        let mut app = crate::SolveApp::new(solidcraft_engine::Session::default(), crate::Services::default());
+        assert_eq!(app.preferences.display_quality, "normal");
+        let out = super::set(&mut app, &json!({"display_quality": "fine"})).unwrap();
+        assert_eq!(out["display_quality"], "fine");
+        assert!(super::set(&mut app, &json!({"display_quality": "silky"})).unwrap_err().contains("coarse, normal, fine or ultra"));
+        assert_eq!(app.preferences.display_quality, "fine");
+        assert_eq!(super::lenient(&json!({"display_quality": "ultra"})).display_quality, "ultra");
+        super::defaults(&mut app, super::PAGE_GRAPHICS);
+        assert_eq!(app.preferences.display_quality, "normal");
+    }
+
     #[test]
     fn a_value_this_version_does_not_understand_keeps_the_other_preferences() {
         use serde_json::json;