stroblme
b757d6e8d6
Placeholder for the hand-written nanobind bindings over OCCT (roadmap Phase 10 in the app repo). Carries the gitignore for a scikit-build-core/CMake extension plus the OCCT build trees, and keeps .secrets — the Gitea publish PAT — out of history.
48 lines
2.1 KiB
Markdown
48 lines
2.1 KiB
Markdown
# n3xd-ocp
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Hand-written [nanobind](https://github.com/wjakob/nanobind) bindings for the
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OpenCASCADE (OCCT) geometry kernel, covering exactly the surface the N3XD CAD
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backend uses — roughly 140 symbols across 48 `OCP.*` modules, not all of OCCT.
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The package installs as a top-level `OCP`, so it is a drop-in replacement for
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`cadquery-ocp-novtk` and the app's 437 import sites stay untouched.
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Status: **not started.** The plan lives in the app repo at
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`docs-private/reference/roadmap.md` (Phase 10), with the binding-layer
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background in `docs-private/architecture/geometry-kernel.md`.
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## Why
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`cadquery-ocp` lags OCCT (it wraps 7.9.3; OCCT 8.0 shipped 2026-05), builds
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Windows and macOS wheels we never use, and until recently forced a 638 MB VTK
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dependency into the image. Binding *call* overhead is not a bottleneck — the
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CAD hotspots live inside the C++ kernel — so this exists for version velocity,
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footprint, and two defects that a binding we control prevents by construction:
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- OCCT sub-shapes are returned **by value**, so a wrapper can never alias a
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`TShape` whose owner has died (this segfaulted a process-global face memo).
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- Executing constructors (the two-argument `BRepAlgoAPI_*` forms) are **not
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bound**, so the double-execution footgun is unrepresentable.
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It also releases the GIL around kernel calls and ships type stubs, neither of
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which upstream does.
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## Build
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OCCT is compiled once into a builder image and reused; it is never built on the
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production host (4 cores, and a kernel build is multi-hour). Wheels are built
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here on a dev box and published to the Gitea package registry:
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```bash
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uv publish --publish-url https://git.stroblme.de/api/packages/N3XD/pypi dist/*.whl
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```
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Credentials go in `.secrets` (gitignored) as `UV_PUBLISH_USERNAME` /
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`UV_PUBLISH_PASSWORD`. Consumers read anonymously — the package is public — via
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`https://git.stroblme.de/api/packages/N3XD/pypi/simple/`.
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Versions are `<occt-version>.N`, so the kernel a wheel wraps is readable from
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its version alone. The registry refuses to republish a version; iteration
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builds therefore carry a `.devN` suffix and are the only ones the registry's
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cleanup rule collects.
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