n3xd-ocp (7.9.3.1.dev1)
Installation
pip install --index-url About this package
nanobind bindings for the OpenCASCADE geometry kernel (drop-in OCP)
n3xd-ocp
Hand-written nanobind bindings for the
OpenCASCADE (OCCT) geometry kernel, covering exactly the surface the N3XD CAD
backend uses — roughly 140 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 437 import sites stay untouched.
Status: not started. The plan lives in the app repo at
docs-private/reference/roadmap.md (Phase 10), with the binding-layer
background in docs-private/architecture/geometry-kernel.md.
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:
uv publish --publish-url https://git.stroblme.de/api/packages/N3XD/pypi dist/*.whl
Credentials go in .secrets (gitignored) as UV_PUBLISH_USERNAME /
UV_PUBLISH_PASSWORD. Consumers read anonymously — the package is public — via
https://git.stroblme.de/api/packages/N3XD/pypi/simple/.
Versions are <occt-version>.N, 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.