Polar duplicate: use sketch-based points/plane when a sketch is available

[trailcode]

[Draft] Polar duplicate: sketch-based reference when a sketch is available

Suggested labels: enhancement, sketch, ux

Repo: trailcode/EzyCad

---

Title (GitHub)

Polar duplicate: use sketch-based points/plane when a sketch is available

Body (GitHub)

Summary

Polar duplicate today builds its polar arm and rotation using the current sketch plane and Sketch_nodes::snap for the first pick (see Shp_polar_dup::move_point / add_point in src/shp_polar_dup.cpp). There is a product gap: when a sketch exists, users expect polar array placement and reference geometry to feel explicitly tied to sketch points, edges, or the sketch datum, not only a bbox center plus plane snap.

Current behavior (for context)

• Rotation axis uses view().curr_sketch().get_plane() and edge endpoints derived from the polar arm edge on that plane.
• First drag uses get_shape_bbox_center(m_shps[0]->Shape()) as one end of the arm (see TODO in code: "consider all shapes").
• Successful Dup removes originals via delete_operation_shps_() (documented elsewhere; separate from sketch reference).

Desired direction (open for design)

• When a sketch is available (e.g. current sketch has geometry or user is in a sketch-centric workflow), prefer:
  • Snapping the polar origin or arm endpoints to sketch nodes / edges / meaningful sketch references where possible.
  • Clear UX when no sketch is active (fallback to today or a world pick path).
• Align with Reader-first / pragmatic DRY in ezycad_code_style.md: keep polar-dup interaction discoverable in one place (Options + mouse flow) without scattering sketch rules across unrelated tools.

Acceptance criteria (draft)

• With an active sketch, polar duplicate picks can use sketch-backed snaps (exact rules TBD with design).
• Without a sketch (or when explicitly in pure solid mode), behavior remains defined and documented (no silent failure).
• Update in-app hints / tooltips if needed so users know plane and snap source.

Links / notes

• Code entry points: src/shp_polar_dup.cpp, Occt_view::on_mode sketch visibility for Mode::Shape_polar_duplicate in src/occt_view.cpp.

---

Metadata (do not paste into GitHub)

• Draft path: agents/issues/004-polar-dup-sketch-based-reference.md