feat(text): TEXTFILL — fill or hollow TrueType glyphs (#260)

TEXTFILL 1 (default) fills TrueType text; TEXTFILL 0 draws it hollow
(outline only). Settable directly or via SETVAR, 0/1 or ON/OFF. SHX/LFF
stroke fonts are unaffected.

Reuses the existing stroke-SDF path: bake_glyph treats a TTF glyph as a
stroke (outline) field instead of a signed fill field when TEXTFILL is
off. Toggling resets the glyph atlas and re-tessellates text so quads
pick up the re-baked tiles. Persisted in user settings.

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

src/app/commands/mod.rs

@@ -328,6 +328,7 @@ inventory::submit!(crate::command::CommandRegistration {
         "TCASE",
         "TEXTMASK",
         "TEXTFIT",
+        "TEXTFILL",
         "TCOUNT",
         "ARCTEXT",
         // Jogged radius dimension.

src/app/commands/styleprops.rs

@@ -527,6 +527,7 @@ impl OpenCADStudio {
             cmd if matches!(
                 cmd.split_whitespace().next().unwrap_or(""),
                 "MIRRTEXT"
+                    | "TEXTFILL"
                     | "ATTREQ"
                     | "ATTDIA"
                     | "DIMASSOC"
@@ -678,6 +679,23 @@ impl OpenCADStudio {
                                     .ok_or_else(|| "SETVAR: 0 or 1 required.".into()),
                                 None => Ok((format!("MIRRTEXT = {}", h.mirror_text as i32), false)),
                             },
+                            // Global (not stored in the drawing): fill vs. hollow
+                            // TrueType text. The active tab re-tessellates below.
+                            "TEXTFILL" => match &value {
+                                Some(v) => parse_bool(v)
+                                    .map(|b| {
+                                        crate::scene::text::sdf_atlas::set_textfill(b);
+                                        (format!("TEXTFILL = {}", b as i32), true)
+                                    })
+                                    .ok_or_else(|| "SETVAR: 0 or 1 required.".into()),
+                                None => Ok((
+                                    format!(
+                                        "TEXTFILL = {}",
+                                        crate::scene::text::sdf_atlas::textfill() as i32
+                                    ),
+                                    false,
+                                )),
+                            },
                             "ATTREQ" => match &value {
                                 Some(v) => parse_bool(v)
                                     .map(|b| {
@@ -1227,6 +1245,11 @@ impl OpenCADStudio {
                         }
                         Err(e) => self.command_line.push_error(&e),
                     }
+                    // TEXTFILL reset the glyph atlas; re-tessellate so text picks
+                    // up the re-baked filled / hollow tiles.
+                    if name == "TEXTFILL" {
+                        self.tabs[i].scene.bump_geometry();
+                    }
                 }
             }
 

src/app/settings.rs

@@ -103,6 +103,8 @@ pub struct UserSettings {
     pub plugin_repos: Vec<String>,
     /// Controls whether the TEXTEDIT command repeats automatically (0 = Multiple, 1 = Single).
     pub texteditmode: bool,
+    /// TEXTFILL: fill TrueType glyphs (true) or draw them hollow (false).
+    pub textfill: bool,
     /// When true, saving over an existing file first copies it to a sibling
     /// `<name>.bak` so a faulty or accidental save can be recovered (#205).
     pub backup_on_save: bool,
@@ -142,6 +144,7 @@ impl Default for UserSettings {
             disabled_plugins: Vec::new(),
             plugin_repos: Vec::new(),
             texteditmode: false,
+            textfill: true,
             backup_on_save: true,
             file_assoc_enabled: true,
             savetime_min: 10,
@@ -190,6 +193,7 @@ impl UserSettings {
                     }
                 }
                 "backup_on_save" => s.backup_on_save = val == "1",
+                "textfill" => s.textfill = val == "1",
                 "file_assoc_enabled" => s.file_assoc_enabled = val == "1",
                 "savetime_min" => {
                     if let Ok(v) = val.parse::<i32>() {
@@ -237,7 +241,7 @@ impl UserSettings {
             .collect::<Vec<_>>()
             .join(",");
         let body = format!(
-            "dyn={}\northo={}\npolar={}\npolar_increment_deg={}\nosnap={}\notrack={}\ndefault_assoc_prompted={}\nsnap_modes={}\ndisabled_plugins={}\nplugin_repos={}\ntexteditmode={}\nbackup_on_save={}\nfile_assoc_enabled={}\nsavetime_min={}\nbg_color={}\npaper_bg_color={}\n",
+            "dyn={}\northo={}\npolar={}\npolar_increment_deg={}\nosnap={}\notrack={}\ndefault_assoc_prompted={}\nsnap_modes={}\ndisabled_plugins={}\nplugin_repos={}\ntexteditmode={}\ntextfill={}\nbackup_on_save={}\nfile_assoc_enabled={}\nsavetime_min={}\nbg_color={}\npaper_bg_color={}\n",
             b(self.dyn_input),
             b(self.ortho),
             b(self.polar),
@@ -249,6 +253,7 @@ impl UserSettings {
             self.disabled_plugins.join(","),
             self.plugin_repos.join(","),
             self.texteditmode,
+            b(self.textfill),
             b(self.backup_on_save),
             b(self.file_assoc_enabled),
             self.savetime_min,

src/app/update/file.rs

@@ -79,6 +79,7 @@ impl OpenCADStudio {
             },
             plugin_repos: self.plugin_repos.clone(),
             texteditmode: self.texteditmode,
+            textfill: crate::scene::text::sdf_atlas::textfill(),
             backup_on_save: self.backup_on_save,
             file_assoc_enabled: self.file_assoc_enabled,
             savetime_min: self.savetime_min,
@@ -100,6 +101,7 @@ impl OpenCADStudio {
         self.disabled_plugins = s.disabled_plugins.iter().cloned().collect();
         self.plugin_repos = s.plugin_repos.clone();
         self.texteditmode = s.texteditmode;
+        crate::scene::text::sdf_atlas::set_textfill(s.textfill);
         self.backup_on_save = s.backup_on_save;
         self.file_assoc_enabled = s.file_assoc_enabled;
         self.savetime_min = s.savetime_min;

src/scene/text/sdf_atlas.rs

@@ -39,6 +39,24 @@ pub fn text_atlas() -> &'static Mutex<GlyphAtlas> {
     ATLAS.get_or_init(|| Mutex::new(GlyphAtlas::new(1024, 1024)))
 }
 
+/// TEXTFILL system variable — `true` fills TrueType glyphs (default), `false`
+/// draws them hollow (outline only). Global, like the AutoCAD system variable.
+static TEXTFILL: std::sync::atomic::AtomicBool = std::sync::atomic::AtomicBool::new(true);
+
+pub fn textfill() -> bool {
+    TEXTFILL.load(std::sync::atomic::Ordering::Relaxed)
+}
+
+/// Set TEXTFILL and drop the cached glyphs so they re-bake filled / hollow.
+/// Callers must re-tessellate text (`bump_geometry`) so quads pick up the
+/// re-baked tiles.
+pub fn set_textfill(on: bool) {
+    TEXTFILL.store(on, std::sync::atomic::Ordering::Relaxed);
+    if let Ok(mut a) = text_atlas().lock() {
+        a.reset();
+    }
+}
+
 /// Debug: when env `OCS_TEXT_BOX` is set, each SDF text run also emits a
 /// rectangle outline around its glyph bounds so the text pick box is visible.
 /// Read once.
@@ -173,6 +191,12 @@ impl GlyphAtlas {
         self.dirty = false;
     }
 
+    /// Drop every cached glyph and re-init the texture, so glyphs re-bake on
+    /// next use (e.g. after TEXTFILL toggles between fill and outline).
+    pub fn reset(&mut self) {
+        *self = GlyphAtlas::new(self.width, self.height);
+    }
+
     /// Look up a glyph's atlas placement, baking + packing it on first use.
     /// Returns `None` for whitespace/empty glyphs (nothing to draw) and when the
     /// atlas is full (Phase 1 is single-page; callers should treat `None` as
@@ -229,7 +253,10 @@ impl GlyphAtlas {
 
 /// Rasterize a glyph into an SDF tile. `None` if the glyph has no ink.
 fn bake_glyph(g: &Glyph) -> Option<BakedTile> {
-    let filled = !g.fill_tris.is_empty();
+    // TEXTFILL 0 renders TrueType glyphs hollow: bake them as a stroke field
+    // (outline) instead of a signed fill field. Stroke fonts (no fill tris) are
+    // unaffected.
+    let filled = textfill() && !g.fill_tris.is_empty();
 
     // Ink bounding box over all strokes (and fill triangles, for safety).
     let (mut min_x, mut min_y) = (f32::INFINITY, f32::INFINITY);