feat(grid): the coloured grid axis lines can be turned off (#1815)

Drafting Settings > Snap and Grid gains "Display grid axis lines",
kept with the other grid settings; the grid itself stays as it is.

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

src/app/drafting_settings.rs

@@ -25,6 +25,7 @@ impl DraftingSettingsState {
             grid_major_input: format!("{}", app.grid_major_every),
             grid_adaptive: app.grid_adaptive,
             grid_beyond_limits: app.grid_beyond_limits,
+            grid_axes: app.grid_axes,
             isometric: app.isometric_drafting,
             iso_plane: app.iso_plane,
             snap_angle_deg: app.snap_angle_deg,
@@ -99,6 +100,7 @@ impl OpenCADStudio {
         self.grid_major_every = gm;
         self.grid_adaptive = state.grid_adaptive;
         self.grid_beyond_limits = state.grid_beyond_limits;
+        self.grid_axes = state.grid_axes;
         self.snapper.grid_snap_on = state.snap_on;
         self.snapper.snap_spacing_x = sx;
         self.snapper.snap_spacing_y = sy;
@@ -151,6 +153,7 @@ mod tests {
             grid_major_input: "5".to_string(),
             grid_adaptive: true,
             grid_beyond_limits: true,
+            grid_axes: true,
             isometric: false,
             iso_plane: crate::app::settings::IsoPlane::Left,
             snap_angle_deg: 0.0,
@@ -193,6 +196,7 @@ mod tests {
             grid_major_input: "5".to_string(),
             grid_adaptive: true,
             grid_beyond_limits: true,
+            grid_axes: true,
             isometric: false,
             iso_plane: crate::app::settings::IsoPlane::Left,
             snap_angle_deg: 0.0,

src/app/mod.rs

@@ -756,6 +756,8 @@ pub(super) struct OpenCADStudio {
     pub grid_adaptive: bool,
     /// Display the grid beyond LIMITS (infinite) instead of clipping to them.
     pub grid_beyond_limits: bool,
+    /// Draw the coloured X/Y axis lines through the grid origin.
+    pub grid_axes: bool,
     /// Dynamic input overlay (F12): show coordinate tooltip near cursor.
     dyn_input: bool,
     /// Dynamic input mode (DYNMODE): 0=off, 1=pointer, 2=dimensional, 3=both.
@@ -3567,6 +3569,7 @@ pub enum Message {
     DraftingSettingsGridMajorChanged(String),
     DraftingSettingsToggleAdaptiveGrid,
     DraftingSettingsToggleBeyondLimits,
+    DraftingSettingsToggleGridAxes,
     DraftingSettingsToggleEqualSnap,
     DraftingSettingsToggleIsometric,
     DraftingSettingsSetIsoPlane(crate::app::settings::IsoPlane),
@@ -4754,6 +4757,7 @@ impl OpenCADStudio {
             grid_major_every: 5,
             grid_adaptive: true,
             grid_beyond_limits: true,
+            grid_axes: true,
             dyn_input: true,
             dyn_mode: 3,
             options_tab: crate::ui::window::options::OptionsTab::General,

src/app/settings.rs

@@ -704,6 +704,9 @@ pub struct UserSettings {
     /// Display grid beyond LIMITS (default on, matches dialog).
     #[serde(default = "default_true")]
     pub grid_beyond_limits: bool,
+    /// Draw the coloured X/Y axis lines through the grid origin.
+    #[serde(default = "default_true")]
+    pub grid_axes: bool,
     /// Most-recently-inserted block names, most recent first, capped to 20.
     /// Used to rank INSERT suggestions without touching the drawing file.
     #[serde(default)]
@@ -1052,6 +1055,7 @@ impl Default for UserSettings {
             grid_major_every: 5,
             grid_adaptive: true,
             grid_beyond_limits: true,
+            grid_axes: true,
             block_mru: Vec::new(),
             block_freq: std::collections::HashMap::new(),
             block_recent: Vec::new(),

src/app/update/file.rs

@@ -925,6 +925,7 @@ impl OpenCADStudio {
             grid_major_every: self.grid_major_every,
             grid_adaptive: self.grid_adaptive,
             grid_beyond_limits: self.grid_beyond_limits,
+            grid_axes: self.grid_axes,
             block_mru: self.block_mru.clone(),
             block_freq: self.block_freq.clone(),
             block_recent: self.block_palette.recent.clone(),
@@ -1110,6 +1111,7 @@ impl OpenCADStudio {
         self.grid_major_every = crate::app::settings::sanitize_grid_major(s.grid_major_every);
         self.grid_adaptive = s.grid_adaptive;
         self.grid_beyond_limits = s.grid_beyond_limits;
+        self.grid_axes = s.grid_axes;
         // Block usage: clone but cap to sane sizes (MRU 20, freq map 200)
         self.block_mru = s.block_mru.iter().take(20).cloned().collect();
         self.block_freq = s

src/app/update/mod.rs

@@ -6401,6 +6401,12 @@ impl OpenCADStudio {
                 }
                 Task::none()
             }
+            Message::DraftingSettingsToggleGridAxes => {
+                if let Some(state) = &mut self.drafting_settings_state {
+                    state.grid_axes = !state.grid_axes;
+                }
+                Task::none()
+            }
             Message::DraftingSettingsToggleEqualSnap => {
                 if let Some(state) = &mut self.drafting_settings_state {
                     state.snap_equal = !state.snap_equal;

src/app/view/mod.rs

@@ -627,6 +627,7 @@ bg={bg_ms:.1}ms n={view_count}"
             let grid_style = crate::ui::overlay::GridStyle {
                 opacity: self.model_space.grid_opacity,
                 bg_luminance: bg_lum,
+                axes: self.grid_axes,
             };
             crate::ui::overlay::grid_overlay(grid, grid_style)
         };