stroblme
6139852768
Builds n3xd-ocp end to end and publishes 7.9.3.1.dev1 to the Gitea registry, where it installs anonymously and passes its suite. - occt/Dockerfile: OCCT 7.9.3 compiled once into a manylinux_2_28 builder image (base digest + tarball sha256 pinned), Draw/VTK/Tk/Xlib/OpenGL off, FreeType on, -O2 without fast-math or march=native. A final layer asserts TKService/TKV3d exist with no libGL/libX11 DT_NEEDED, which is what lets the app image drop libgl1/libx11-6. Mounted into, never built FROM. - scikit-build-core + nanobind STABLE_ABI -> one cp312-abi3 extension that registers every OCP.* submodule via PyImport_AddModule, so `import OCP.TopoDS` needs no shim and cls.__module__ is right. Version <occt>.N is asserted against the OCCT found, keeping occt_version() truthful. - occt_handle.h: type caster for opencascade::handle<T> over OCCT's intrusive refcount. Wrappers are non-owning instances holding exactly one handle in their keep-alive list, reusing an existing wrapper so identity survives a round trip. Transient constructors go through ocp_new (never nb::init<>, which would let OCCT delete nanobind's storage); the caster refuses a refcount-0 object rather than corrupt the heap. Verified under ASAN with no memory-safety errors, plus an RSS bound over 50k create/destroy cycles. - Sub-shapes are returned by value everywhere, making the TShape lifetime class that segfaulted a process-global face memo unrepresentable. - Standard_Failure derives RuntimeError, with ~20 concrete types dispatched on the dynamic OCCT type (cad_pool marshals failures home by type name). - Inc 0 surface: gp subset, TopAbs, TopoDS (+ downcasts), TopExp, TopLoc, TopTools, BRep, BinTools, Poly, Standard. 34 of the app's 139 symbols. - n3xd_ocp: additive APIs kept out of the OCP namespace so parity testing stays meaningful. bintools (shape <-> bytes, GIL-free, byte-identical) and _debug. Two findings worth the record, both verified against the stock wheel rather than assumed: upstream binds __hash__ but leaves __eq__ at identity, which is exactly what geom_memo.py's hash-bucket + IsSame scan is built around, so we match it instead of "fixing" it; and BinTools can release the GIL after all, by slurping the file-like object instead of bridging a streambuf that would call back into Python. Gate: BREP round-trips are byte-identical to cadquery-ocp-novtk across six fixtures (the generator asserts stock idempotency first). That matters beyond IPC — derive.py content-addresses BREP payloads by sha256 and stores the ref.
3.0 KiB
n3xd-ocp
Hand-written nanobind bindings for the
OpenCASCADE (OCCT) geometry kernel, covering exactly the surface the N3XD CAD
backend uses — 139 symbols across 48 OCP.* modules, not all of OCCT.
The package installs as a top-level OCP, so it is a drop-in replacement for
cadquery-ocp-novtk and the app's 442 import sites stay untouched.
Status: Inc 0 (spike) shipped — build system, OCCT builder image, handle
model, and the first module surface (gp, TopAbs, TopoDS, TopExp,
TopLoc, TopTools, BRep, BinTools, Poly, Standard), published as
7.9.3.1.dev1. BREP serialisation is byte-identical to the stock wheel, which
is the gate that mattered: the pools and the content-addressed derive payloads
both depend on it. Coverage is 34 of the 139 symbols the app imports; the rest
lands in increments 1-4 (roadmap 10C).
Start with docs/design.md for the decisions,
docs/building.md to build one, and
docs/adding-symbols.md to extend the surface. The
phase plan lives in the app repo at docs-private/reference/roadmap.md
(Phase 10).
Why
cadquery-ocp lags OCCT (it wraps 7.9.3; OCCT 8.0 shipped 2026-05), builds
Windows and macOS wheels we never use, and until recently forced a 638 MB VTK
dependency into the image. Binding call overhead is not a bottleneck — the
CAD hotspots live inside the C++ kernel — so this exists for version velocity,
footprint, and two defects that a binding we control prevents by construction:
- OCCT sub-shapes are returned by value, so a wrapper can never alias a
TShapewhose owner has died (this segfaulted a process-global face memo). - Executing constructors (the two-argument
BRepAlgoAPI_*forms) are not bound, so the double-execution footgun is unrepresentable.
It also releases the GIL around kernel calls and ships type stubs, neither of which upstream does.
Build
OCCT is compiled once into a builder image and reused; it is never built on the production host (4 cores, and a kernel build is multi-hour). Wheels are built here on a dev box and published to the Gitea package registry.
make image # once, ~40 min: compiles OCCT 7.9.3 into the builder image
make dev # inner loop: incremental compile + tests
make wheel # compile, stubs, auditwheel, self-containment smoke test
make publish # -> https://git.stroblme.de/api/packages/N3XD/pypi
Credentials go in .secrets (gitignored) as UV_PUBLISH_USERNAME /
UV_PUBLISH_PASSWORD. Consumers read anonymously — the package is public:
uv pip install --index-url https://git.stroblme.de/api/packages/N3XD/pypi/simple/ \
--prerelease=allow n3xd-ocp
Versions are <occt-version>.N, enforced at configure time against the OCCT
actually found, so the kernel a wheel wraps is readable from its version alone.
The registry refuses to republish a version; iteration builds therefore carry a
.devN suffix and are the only ones the registry's cleanup rule collects.