Migrate export_step / export_stl / export_brep off FreeCAD, onto build123d + OCP — Phase 1: Rewrite `_primitive_to_shape` to use OCP constructors #41

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opened 2026-06-24 03:24:30 +00:00 by Mark · 0 comments

Mark commented

2026-06-24 03:24:30 +00:00

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Phase 1: Rewrite `_primitive_to_shape` to use OCP constructors

Goal: Replace pc2cad.py:3592 _primitive_to_shape(FreeCAD, Part, primitive)
with an OCP-only equivalent that does not take FreeCAD/Part as parameters.
This is the per-primitive shape constructor every boolean and export op
funnels through, so it is the choke point.

Approach:

Sphere → BRepPrimAPI_MakeSphere(center, radius).Shape()
Cylinder → BRepPrimAPI_MakeCylinder(axis_point, axis_dir, radius, height).Shape()
Cone → BRepPrimAPI_MakeCone(...) (derive base/apex from primitive)
Plane (polygon face) → BRepBuilderAPI_MakeFace from the polygon's
Poly_Triangulation or from the inlier-hull polygon as a TopoDS_Wire
on a plane.
New signature: _primitive_to_shape(primitive: Primitive) -> TopoDS_Shape.
Drop the FreeCAD, Part params.

Files: pc2cad.py:3592-3690 (rewrite _primitive_to_shape),
pc2cad.py:3583-3591 (delete _freecad_import).

Acceptance:

New function exists, old signature gone, no FreeCAD import.
git grep "def _primitive_to_shape" pc2cad.py shows the new signature.
All 8 boolean call sites (lines 3831, 4040, etc.) updated to the new
signature; lint passes.
All existing tests still pass (no behavioural change yet — just signature).

Decomposed from pc2cad#23

## Phase 1: Rewrite `_primitive_to_shape` to use OCP constructors **Goal:** Replace `pc2cad.py:3592 _primitive_to_shape(FreeCAD, Part, primitive)` with an OCP-only equivalent that does not take FreeCAD/Part as parameters. This is the per-primitive shape constructor every boolean and export op funnels through, so it is the choke point. **Approach:** - Sphere → `BRepPrimAPI_MakeSphere(center, radius).Shape()` - Cylinder → `BRepPrimAPI_MakeCylinder(axis_point, axis_dir, radius, height).Shape()` - Cone → `BRepPrimAPI_MakeCone(...)` (derive base/apex from primitive) - Plane (polygon face) → `BRepBuilderAPI_MakeFace` from the polygon's `Poly_Triangulation` or from the inlier-hull polygon as a `TopoDS_Wire` on a plane. - New signature: `_primitive_to_shape(primitive: Primitive) -> TopoDS_Shape`. Drop the FreeCAD, Part params. **Files:** `pc2cad.py:3592-3690` (rewrite `_primitive_to_shape`), `pc2cad.py:3583-3591` (delete `_freecad_import`). **Acceptance:** - New function exists, old signature gone, no FreeCAD import. - `git grep "def _primitive_to_shape" pc2cad.py` shows the new signature. - All 8 boolean call sites (lines 3831, 4040, etc.) updated to the new signature; lint passes. - All existing tests still pass (no behavioural change yet — just signature). --- --- _Decomposed from [pc2cad#23](https://forgejo.tail018ac4.ts.net/Mark/pc2cad/issues/23)_