OCCTSwiftIO

📖 Documentation: https://secondmouseau.github.io/OCCTSwiftIO/

Headless file I/O for the OCCTSwift ecosystem. No Viewport dependency — safe for CLIs, batch pipelines, and server-side workflows. The package ships two products so consumers take only what they need:

Product	Depends on OCCT?	What it's for
MeshIO	No (pure Swift)	3D mesh formats → a neutral Mesh (positions + indices).
OCCTSwiftIO	Yes	CAD B-Rep load/export as OCCT Shapes + JWW (2D vector) load.

The split lets OCCT-free consumers (e.g. a raw-mesh pipeline) read meshes without pulling in the 1.3 GB kernel; OCCTSwiftIO builds on top of MeshIO and adds the kernel-backed formats.

Format coverage

Format	Read	Write	Product
STL (ascii+binary)	✅	✅	MeshIO
OBJ	✅	✅	MeshIO
PLY (ascii+binary)	✅	✅	MeshIO
glTF / GLB	✅	✅	MeshIO
3MF	✅	✅	MeshIO
PMX (MikuMikuDance)	✅	—	MeshIO
DirectX .x	✅	—	MeshIO
STEP / IGES / BREP	✅	✅*	OCCTSwiftIO
JWW (Jw_cad, 2D vector)	✅	—	OCCTSwiftIO

_{*OCCTSwiftIO ExportManager exports OCCT Shapes to STEP / BREP / OBJ / PLY / glTF / GLB.}

Install

dependencies: [
    .package(url: "https://github.com/SecondMouseAU/OCCTSwiftIO.git", from: "1.4.0"),
],
// then add the product(s) you need:
.target(name: "YourTarget", dependencies: [
    .product(name: "MeshIO", package: "OCCTSwiftIO"),        // mesh, no OCCT
    .product(name: "OCCTSwiftIO", package: "OCCTSwiftIO"),   // CAD + JWW (pulls OCCT)
]),

MeshIO — pure-Swift mesh I/O

import MeshIO

let mesh = try MeshIO.load(contentsOf: url)        // .stl/.obj/.ply/.gltf/.glb/.3mf/.pmx/.x
print(mesh.vertexCount, mesh.triangleCount, mesh.bounds as Any)

try MeshIO.write(mesh, to: outURL)                 // format inferred from extension
try MeshIO.write(mesh, to: stlURL, format: .stl, asciiSTL: true)

Mesh is a value type (positions: [SIMD3<Float>], indices: [UInt32]). PMX/.x are read via the standalone SwiftPMX / SwiftX packages; 3MF via ThreeMF; glTF read via SwiftGLTF (write is native).

OCCTSwiftIO — CAD + JWW

import OCCTSwift
import OCCTSwiftIO

// STEP / IGES / BREP → shapes + colors + AP242 metadata.
let result = try await ShapeLoader.load(from: stepURL, format: .step)

// JWW (Jw_cad 2D drawing) → a compound of OCCT edges (lines, arcs/circles, points).
let drawing = try await ShapeLoader.load(from: jwwURL, format: .jww)

// Export shapes to STEP / BREP / OBJ / PLY / glTF / GLB.
try await ExportManager.export(shapes: result.shapes, format: .glb, to: outURL)

For body-producing loaders (CPU mesh + pick data for AIS), use OCCTSwiftTools, which wraps this package.

Architecture position

OCCTSwiftTools     (bridge — Shape ↔ ViewportBody)
       ↑
OCCTSwiftIO        ← this repo (headless file I/O)        MeshIO  ← pure-Swift mesh (no OCCT)
       ↑                                                     ↑
OCCTSwift          (B-Rep kernel)              SwiftPMX / SwiftX / ThreeMF / SwiftGLTF / SwiftJWW

Hard rule: no Viewport dependency in this package. Produce ViewportBodys in OCCTSwiftTools.

License

LGPL-2.1 (inherited from OCCTSwift / OCCT). The mesh-format reader packages carry their own permissive licenses (MIT / BSD-3).