A left press on the view cube held and dragged orbits the view: the press is not a click until it moves or is held past one, then the pointer grabs and the view orbits about its centre as the other orbits do (the move it took to tell a drag from a click turns the view too). A press that doesn't move is still a click on the face, edge or corner. While the cube is dragged its hover highlight is off, the release is not a click, and the navigation bar's orbit or pan tool doesn't also act on the drag. A press on a floating window over the cube is the window's and starts no orbit, as with the cube's hover. Tests: the s39 scenario drags 48 px right from FRONT and the view turns 22° without clicking the face

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

crates/ui-egui/src/viewport.rs

@@ -51,6 +51,9 @@ pub struct ViewportState {
     pub orbit_pivot: Option<Vec3>,
     /// Continuous orbit: the view turns about the vertical until the next click or key.
     pub spin: bool,
+    /// A left press on the view cube, held: where the pointer was when the view last orbited
+    /// (dragging from the cube orbits; a press that doesn't move is a click).
+    pub cube_drag: Option<Pos2>,
     pub build_ms: f64,
     /// The right-click menu, open at this screen position.
     pub context_menu: Option<Pos2>,
@@ -1401,7 +1404,7 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
         let (dx, dy) = (delta.x as f64, delta.y as f64);
         let mode = if middle || secondary_down {
             crate::prefs::nav_mode(app, middle, secondary_down, mods)
-        } else if primary_down {
+        } else if primary_down && app.viewport.cube_drag.is_none() {
             app.viewport.nav
         } else {
             None
@@ -2080,21 +2083,55 @@ fn cube_basis(cam: &Camera) -> (Vec3, Vec3, Vec3) {
     (cam.to_frame(r), cam.to_frame(u), cam.to_frame(b))
 }
 
+/// A left press on the view cube held and dragged orbits the view about its centre, the model
+/// following the pointer as with the other orbits. The press itself turns nothing: a press that
+/// doesn't move is a click. A press on a floating window over the cube is the window's. Returns
+/// whether the cube is being dragged (held past a click).
+fn view_cube_orbit(app: &mut SolveApp, ui: &mut egui::Ui, rect: Rect, targets: &[CubeTarget], c: Pos2) -> bool {
+    let (pressed, down, decided, origin, pos) = ui.input(|i| {
+        let p = &i.pointer;
+        (p.primary_pressed(), p.primary_down(), p.is_decidedly_dragging(), p.press_origin(), p.interact_pos())
+    });
+    if pressed && ui.rect_contains_pointer(rect) {
+        let (r, u, b) = cube_basis(&app.cam);
+        let shapes = cube_projected(targets, (r, u, b), c);
+        app.viewport.cube_drag = origin.filter(|p| cube_hit(&shapes, *p).is_some());
+    }
+    if !down {
+        app.viewport.cube_drag = None;
+    }
+    let Some(last) = app.viewport.cube_drag.filter(|_| decided) else { return false };
+    ui.ctx().set_cursor_icon(egui::CursorIcon::Grabbing);
+    // From where the view last turned (the press, at first), so the move it took to tell a drag
+    // from a click turns the view too.
+    if let Some(p) = pos
+        && p != last
+    {
+        app.cancel_view_animation();
+        app.cam.orbit(f64::from(p.x - last.x), f64::from(p.y - last.y));
+        app.viewport.cube_drag = Some(p);
+        ui.ctx().request_repaint();
+    }
+    true
+}
+
 /// The view cube (top right): a cube with chamfered corners. Its 26 targets are the 6 faces
 /// (orthographic views), the 12 edges (the views halfway between their two faces) and the 8
 /// corner facets (iso views); an edge is picked by a band along it on both faces it joins.
-/// Hover lights the target under the pointer, a click turns the view to it, the house goes home.
+/// Hover lights the target under the pointer, a click turns the view to it, a drag from the cube
+/// orbits, the house goes home.
 fn view_cube(app: &mut SolveApp, ui: &mut egui::Ui, rect: Rect) {
     let t = Tokens::get();
     let c = pos2(rect.right() - 80.0, rect.top() + 80.0);
+    let targets = cube_targets();
+    let orbiting = view_cube_orbit(app, ui, rect, &targets, c);
     let (r, u, b) = cube_basis(&app.cam);
     let (wr, wu, _) = app.cam.basis();
     let painter = ui.painter_at(rect);
     let hover = ui.input(|i| i.pointer.hover_pos()).filter(|_| ui.rect_contains_pointer(rect));
-    let targets = cube_targets();
     let drawn = cube_drawn(&targets, (r, u, b), c);
     let shapes = cube_projected(&targets, (r, u, b), c);
-    let hovered = hover.and_then(|h| cube_hit(&shapes, h));
+    let hovered = if orbiting { None } else { hover.and_then(|h| cube_hit(&shapes, h)) };
     // Axis triad from the cube's back corner, drawn first: the cube hides what is behind it.
     // The corner is in the cube's frame, the axes are the world's.
     let o = Vec3::new(-1.0, -1.0, -1.0);

crates/ui-egui/tests/scenarios/s39_view_cube_hover.json

@@ -31,6 +31,11 @@
  {"call": "ui.view", "params": {"view": "home"}},
  {"click": {"handle": "cube:top-back-right"}},
  {"expect": {"camera": {"yaw_deg": -135, "pitch_deg": 35.26}}},
+ {"note": "Pressing on the cube and dragging orbits the view by the whole drag (48 px right: 22°), and the release is not a click on the face pressed."},
+ {"call": "ui.view", "params": {"view": "front"}},
+ {"expect": {"camera": {"yaw_deg": 0, "pitch_deg": 0}}},
+ {"drag": [{"cube": [0, -1, 0]}, {"cube": [1.5, -1, 0]}]},
+ {"expect": {"camera": {"yaw_deg": 22, "pitch_deg": 0}}},
  {"move": [800, 500]},
  {"expect": {"count": {"name": "cube_highlights", "value": 0}}}
 ]

docs/book/src/guide/ui-tour.md

@@ -17,7 +17,8 @@
   Preferences switches to SolidWorks or Inventor style). The view cube and the navigation bar
   change the view: a cube face turns to look straight at it (TOP and BOTTOM keep the current
   heading, squared to the nearest quarter turn), an edge to the view halfway between
-  its two faces, a chamfered corner to that corner's iso view, and the house goes home. Right-click for the marking menu: eight commands around the cursor, plus a
+  its two faces, a chamfered corner to that corner's iso view, and the house goes home.
+  Press on the cube and drag to orbit. Right-click for the marking menu: eight commands around the cursor, plus a
   menu for whatever is under it.
 - **Dialogs** dock on the right with a live preview. Most features also show drag handles and a
   value box in the viewport.