stroblme
9f86845c25
- n3xd_ocp.sample.face_grid: a face's UV grid of points and outward normals in one GIL-free call, sampling exactly where np.linspace does so a caller's fitted surface does not move. - n3xd_ocp.helix: OCCT 8.0's TKHelix, which upstream does not bind at all. Takes Python lists rather than NCollection_Array1. Two things the header does not say, both found by probing: SetParameters wants N+1 diameters for N segments (one per boundary, so a taper interpolates), and the builder is right-hand only -- a negative pitch is error status 12, not a mirrored helix. - Bind BRepPrimAPI_MakeSphere and give inventory.py an EXTRA_SYMBOLS addendum for symbols no app source imports. assay's gen_flow_fixtures has been unrunnable since the 10C cutover for want of it; the gap was wider than --check, since sigdiff is inventory-driven too. Gates: 105 tests, 139/139 symbols, sigdiff clean, ASAN clean, wheel self-contained with no libGL/libX11 DT_NEEDED. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HbTQ2HYWQwdtGmGJwypt6Z
83 lines
3.2 KiB
Markdown
83 lines
3.2 KiB
Markdown
# n3xd-ocp
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Hand-written [nanobind](https://github.com/wjakob/nanobind) wrapper for the OpenCASCADE (OCCT) geometry kernel.
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In comparison to [`cadquery-ocp](https://github.com/cadquery/OCP), we get superlinear 7.0x speedup on the use cases in `n3xd`.
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Start with [docs/design.md](docs/design.md) for the decisions,
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[docs/building.md](docs/building.md) to build one, and
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[docs/adding-symbols.md](docs/adding-symbols.md) to extend the surface.
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## Installation
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As packages sit on our Gitea instance for, you must install by providing the specific url, like:
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```bash
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uv pip install --index-url https://git.stroblme.de/api/packages/N3XD/pypi/simple/ \
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--prerelease=allow n3xd-ocp
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```
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Versions are `<occt-version>.N`, enforced at configure time against the OCCT actually found.
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## Usage
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`OCP` mirrors [`cadquery-ocp`](https://github.com/cadquery/OCP) symbol-for-symbol, so code written against it runs unchanged:
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```python
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from OCP.BRepPrimAPI import BRepPrimAPI_MakeBox
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from OCP.BRepAlgoAPI import BRepAlgoAPI_Cut
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from OCP.TopTools import TopTools_ListOfShape
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box = BRepPrimAPI_MakeBox(10.0, 20.0, 30.0).Shape()
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hole = BRepPrimAPI_MakeBox(3.0, 3.0, 30.0).Shape()
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args, tools = TopTools_ListOfShape(), TopTools_ListOfShape()
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args.Append(box)
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tools.Append(hole)
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cut = BRepAlgoAPI_Cut()
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cut.SetArguments(args)
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cut.SetTools(tools)
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cut.Build()
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result = cut.Shape()
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```
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One deliberate gap from upstream: constructors that run the algorithm immediately (the two-argument `BRepAlgoAPI_Cut(a, b)` form) aren't bound, only the deferred `SetArguments`/`SetTools`/`Build()` sequence above. See [docs/design.md](docs/design.md) for why.
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`n3xd_ocp` adds a handful of batch operations OCP doesn't have. They run on the same OCCT build and take/return plain `OCP` shapes:
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```python
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import n3xd_ocp
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areas, centroids = n3xd_ocp.measure.face_surface_props(result) # one call for every face
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meshes = n3xd_ocp.tess.extract_meshes(result) # triangulated faces, ready to render
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data = n3xd_ocp.bintools.write_bytes(result) # BREP bytes, no temp file needed
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points, normals, uv_bounds = n3xd_ocp.sample.face_grid(face, 33) # a 33x33 UV grid on one face
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```
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`n3xd_ocp.helix` reaches OCCT 8.0's TKHelix, which upstream has no binding for. For N segments it wants N pitches, N turn counts and **N+1 diameters** — one per segment boundary, so consecutive values that differ taper across that segment:
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```python
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from OCP.gp import gp_Ax3, gp_Dir, gp_Pnt
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axis = gp_Ax3(gp_Pnt(0, 0, 0), gp_Dir(0, 0, 1), gp_Dir(1, 0, 0))
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wire, tolerance_reached = n3xd_ocp.helix.pure_helix(axis, 8.0, [1.25], [12.0])
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builder = n3xd_ocp.helix.BuilderHelix() # tapered, e.g. an NPT thread
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builder.set_parameters(axis, [10.0, 8.0], [2.0], [4.0])
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builder.set_approx_parameters(1.0e-4)
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builder.perform()
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```
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## Build
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Wheels are built on a dev box and published to the Gitea package registry [here](https://git.stroblme.de/api/packages/N3XD/pypi).
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If you want to make modifications or build it yourself, here are some shortcuts:
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```bash
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make image # compiles OCCT 8.0.1 into the builder image
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make dev # incremental compile + tests
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make wheel # compile, stubs, auditwheel, self-containment smoke test
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make publish # publish to Gitea using .secret credentials
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``` |