---
title: secondmouseau/occtswiftio
framework: Swift Package Catalog
role: article
path: packages/secondmouseau/occtswiftio
---

# secondmouseau/occtswiftio

📖 **Documentation:** <https://secondmouseau.github.io/OCCTSwiftIO/>

## 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 |

<sub>*OCCTSwiftIO `ExportManager` exports OCCT `Shape`s to STEP / BREP / OBJ / PLY / glTF / GLB.</sub>

## Install

```swift 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

```swift 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]`, `submeshes: [Submesh]`). PMX carries its material sections through as `submeshes` (empty for every other format, including `.x`) — isolate one part of a whole-model PMX with `sub.indexOffset ..< sub.indexOffset + sub.indexCount`. PMX/`.x` are read via the standalone [SwiftPMX](https://github.com/SecondMouseAU/SwiftPMX) / [SwiftX](https://github.com/SecondMouseAU/SwiftX) packages; 3MF via [ThreeMF](https://github.com/tomasf/ThreeMF); glTF read via [SwiftGLTF](https://github.com/schwa/SwiftGLTF) (write is native).

## OCCTSwiftIO — CAD + JWW

```swift 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](https://github.com/SecondMouseAU/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 `ViewportBody`s in OCCTSwiftTools.

## License

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

## Package Metadata

Repository: secondmouseau/occtswiftio

Default branch: main

README: README.md