OCEx

Native Elixir bindings for Open CASCADE Technology.

OCEx provides immutable, immediate geometry operations through a C++ NIF linked to OCCT 7.9.3. Create solids, build profiles, combine and finish bodies, inspect their topology, and exchange STEP, BREP, or STL. No Python runtime or runtime Hex dependencies are required.

For deferred pipelines, workplanes, named assemblies, Livebook previews, and verified STL/3MF bundles, use Smith. OCEx is the lower layer and can be used independently.

A first solid

Install the native prerequisites using the installation guide, then save this as plate.exs:

Mix.install([{:ocex, "~> 0.3.0"}])

{:ok, blank} = OCEx.box(60, 40, 5)
{:ok, bore} = OCEx.cylinder(4, 7)
{:ok, bore} = OCEx.translate(bore, {30, 20, -1})
{:ok, plate} = OCEx.cut(blank, bore)
{:ok, true} = OCEx.valid?(plate)
{:ok, volume} = OCEx.volume(plate)
{:ok, :ok} = OCEx.write_step(plate, "plate.step")
{:ok, :ok} = OCEx.write_stl(plate, "plate.stl", 0.03, 0.5)
IO.puts("Plate volume: #{volume} mm³")

Run elixir plate.exs. For a Mix application, add {:ocex, "~> 0.3.0"} to its dependencies. Mix builds the NIF automatically. The exact OCCT toolkit must remain installed at runtime because the NIF dynamically links its libraries.

Supported operations

See the OCEx module for function arguments and return values and the native geometry guide for units, orientation, profile requirements, selectors, meshing, and exchange behavior.

API conventions

Every public operation returns {:ok, value} or {:error, reason}. Shapes are opaque, garbage-collected native resources. Modeling operations preserve their inputs; edge selections belong to one exact shape revision. Coordinates are {x, y, z} tuples, examples use millimeters, and modeling angles use degrees. Mesh angular deflection uses radians.

OCEx covers the operations needed by Smith, not the full OCCT API. Calls run on BEAM dirty schedulers and are serialized for predictable native ownership. In-process native faults can crash the VM, and kernel operations cannot be forcibly cancelled by terminating an Elixir process. Read errors and lifetimes before integrating a service.

Font-backed text

Version 0.3 converts explicit TTF/OTF font bytes into planar CAD faces using FreeType and HarfBuzz. Inspect shaped glyphs, font metrics and geometry-derived ink bounds, then extrude and compose the result. See font-backed text and the updated native prerequisites in installation.

Planar artwork

OCEx.planar_fill/2 builds XY regions from closed wires using nonzero or even-odd fill rules. OCEx.stroke/3 expands an open or closed wire with explicit width, cap, join and sampling settings. OCEx.affine_transform/2 supports nonuniform XY placement; OCEx.wire_points/2 samples boundaries in traversal order. Smith interprets SVG documents and turns these operations into recipes.

Documentation and development

• Installation and deployment
• Geometry and exchange
• Errors, ownership, and execution
• Changelog
• Repository and test workflow

The suite exercises the real kernel with analytic measurements, topology checks, file round trips, invalid inputs, resource lifetimes, and concurrency. The source installer pins and checksums OCCT; release checks build isolated consumers from package archives.

OCEx is MIT licensed. Open CASCADE Technology has its own license and exception. The installer applies a documented allocator-alignment patch to OCCT 7.9.3 and keeps kernel exception checks enabled. Full OCCT sources and binaries are not bundled in this package.

Working on OCEx

This is a standalone repository. See development for local checks and releasing for this package's release steps.