---
title: secondmouseau/occtswift
framework: Swift Package Catalog
role: article
path: packages/secondmouseau/occtswift
---
# secondmouseau/occtswift
📖 **Documentation & cookbook:**
## Quick Start
### Installation
Add to your `Package.swift`:
```swift dependencies: [ .package(url: "https://github.com/SecondMouseAU/OCCTSwift.git", from: "1.0.0") ] ```
The package ships a pre-built `OCCT.xcframework` as a release asset, so no source build of OCCT is required for end users.
### Usage
```swift import OCCTSwift
// Primitives let box = Shape.box(width: 10, height: 5, depth: 3) let cylinder = Shape.cylinder(radius: 2, height: 10)
// Boolean operations let result = box - cylinder // subtract let combined = box + cylinder // union let common = box & cylinder // intersect
// Modifications let filleted = result.filleted(radius: 0.5) let shelled = filleted.shelled(thickness: -0.3)
// Export try Exporter.writeSTEP(shape: shelled, to: stepURL) try Exporter.writeSTL(shape: shelled, to: stlURL, deflection: 0.05) ```
## Ecosystem
OCCTSwift is the kernel of a layered family of packages, all SemVer-stable from v1.0.0 (OCCT 8.0.0 GA cohort, May 2026). See [`docs/ecosystem.md`](docs/ecosystem.md) for an architecture map and "when to use which" guidance.
| Package | Role | |---------|------| | **OCCTSwift** (this repo) | Core Swift wrapper — shapes, curves, surfaces, OCAF, BRepGraph, drawing/projection, ML samplers. Bundles the OCCT 8.0.0p1 xcframework. | | [OCCTSwiftIO](https://github.com/SecondMouseAU/OCCTSwiftIO) | Headless CAD file I/O — STEP / IGES / STL / OBJ / BREP loaders + glTF / GLB / OBJ / PLY / STEP / BREP exporters. No Viewport dep. | | [OCCTSwiftMesh](https://github.com/SecondMouseAU/OCCTSwiftMesh) | Mesh-domain algorithms — decimation, smoothing, repair (vendors `meshoptimizer`). | | [OCCTSwiftViewport](https://github.com/SecondMouseAU/OCCTSwiftViewport) | Metal-based 3D viewport component (UIKit / AppKit / SwiftUI). | | [OCCTSwiftTools](https://github.com/SecondMouseAU/OCCTSwiftTools) | Bridge layer: converts kernel `Shape` to `ViewportBody` with picking metadata. | | [OCCTSwiftAIS](https://github.com/SecondMouseAU/OCCTSwiftAIS) | High-level interactive services — selection, manipulator widgets, dimension annotations, scene objects. | | [OCCTSwiftScripts](https://github.com/SecondMouseAU/OCCTSwiftScripts) | `occtkit` CLI + ScriptHarness — JSON-driven verbs for compose / reconstruct / drawing-export / metrics / mesh / render-preview / XCAF. | | [OCCTMCP](https://github.com/SecondMouseAU/OCCTMCP) | MCP server exposing CAD modeling to AI tools via Model Context Protocol. | | [simpleOCCTVP](https://github.com/SecondMouseAU/simpleOCCTVP) | Pure C API over OCCT for non-Swift consumers — shape I/O, healing, mesh extraction, offscreen rendering. |
## What's Wrapped
OCCTSwift provides method-level coverage of all user-facing OCCT classes. Key areas:
| Category | Operations | Highlights | |----------|-----------|------------| | Primitives & Sweeps | 36 | box, cylinder, sphere, cone, torus, wedge, pipe, extrude, revolve, loft, thru-sections | | Booleans | 13 | union, subtract, intersect, section, split, cells builder, defeaturing | | Modifications | 33 | fillet (uniform/variable/evolving), chamfer, shell, offset, draft | | Wires & Edges | 56 | rectangle, circle, polygon, arc, BSpline, NURBS, helix, fillet2D, chamfer2D | | 2D Curves | 97 | full Geom2d — lines, conics, BSplines, Bezier, Gcc constraint solver, hatching | | 3D Curves | 84 | full Geom — lines, conics, BSplines, Bezier, interpolation, projection, evaluation | | Surfaces | 88 | analytic, swept, freeform, plate, NLPlate, curvature, projection, trimming (rectangular UV, UV-polygon, or 3D-wire bounded) | | Face / Edge Analysis | 54 | UV queries, normals, curvature, projection, classification, primary axis, surface type predicates | | Feature-Based | 36 | boss, pocket, drill, split, pattern, rib, revolution, draft prism | | Healing & Analysis | 69 | fix, unify, simplify, NURBS convert, sew, wire/face/shell repair | | Measurement | 38 | volume, area, distance, inertia, point classification, proximity, revolution/symmetry axes | | Import/Export | 19 | STEP, IGES, STL, OBJ, PLY, BREP, GLTF/GLB, DXF | | XDE/OCAF | 200+ | assembly, colors, materials, GD&T (32 dimension types + 16 tolerance types, read + write), annotations, transactions, undo/redo, STEP AP242 round-trip | | Math & Solvers | 50+ | root finding, BFGS, PSO, SVD, Gauss, Jacobi, constraint callbacks | | Colors & Materials | 63 | Quantity_Color, sRGB/Lab/HLS, PBR materials, named colors | | Geometry Factories | 90+ | GC/GCE2d/gce factories, convert to BSpline, analytical recognition | | Drawings & Dimensions | 32 | HLR projection, visible/hidden/outline edges, linear/radial/diameter/angular dimensions, centrelines, auto-centreline from revolution axes, DXF R12 writer | | Thread Features | 23 | ThreadForm (ISO-68/Unified), ThreadSpec parser (M5x0.8, 1/4-20 UNC), truncated 60° V-profile, multi-start, runout styles, Shape.threadedHole, Shape.threadedShaft (smooth direct build, single- & multi-start #213/#257; ThreadBuild `.auto`/`.direct`, `.boolean` deprecated #254), Shape.threadedRod (smooth worm/screw from a custom ThreadProfile, boolean-free) | | Sheet Metal | 3 | `SheetMetal.Flange` + `Bend` + `Builder.build` — declarative flange-and-bend composition via extrude + union + fillet |
For the full operation-by-operation mapping to OCCT classes, see [docs/API_REFERENCE.md](docs/API_REFERENCE.md).
## Examples
### Sweep a Profile Along a Path
```swift let profile = Wire.rectangle(width: 5, height: 3) let path = Wire.arc(center: .zero, radius: 50, startAngle: 0, endAngle: .pi / 2) let swept = Shape.sweep(profile: profile, along: path) ```
### XDE Document with Assembly Structure
```swift let doc = try Document.load(from: stepURL)
for node in doc.rootNodes { print("Part: \(node.name ?? "unnamed")") if let color = node.color { print(" Color: \(color.red), \(color.green), \(color.blue)") } if let shape = node.shape { let mesh = shape.mesh(linearDeflection: 0.1) // render with Metal, SceneKit, RealityKit... } } ```
### Parametric Curves for Metal Rendering
```swift let curve = Curve3D.interpolate(points: [ SIMD3(0, 0, 0), SIMD3(5, 10, 0), SIMD3(10, 0, 5) ])! let points = curve.drawAdaptive(curvatureDeflection: 0.1) // Feed to Metal vertex buffer ```
### GLTF Export
```swift try Exporter.writeGLTF(shape: model, to: gltfURL) try Exporter.writeGLB(shape: model, to: glbURL) ```
## Architecture
``` Sources/OCCTSwift/ Swift public API Sources/OCCTBridge/include/ C function declarations (OCCTBridge.h) Sources/OCCTBridge/src/ Objective-C++ implementations (OCCTBridge.mm) Libraries/OCCT.xcframework Pre-built OCCT 8.0.0p1 static library (arm64) Tests/OCCTTests/ Per-domain Swift Testing targets (focused compile/run) ```
Three-layer design: **Swift API** -> **C bridge** (Objective-C++) -> **OCCT C++**
Each OCCT object is managed via opaque handle types with release-on-deinit. See [docs/architecture/overview.md](docs/architecture/overview.md) for details.
## Requirements
- Swift 6.1+ (verified clean on 6.1, 6.2, 6.3) - macOS 12.0+ (arm64) / iOS 15.0+ (arm64) - Xcode 16.0+
### Supported Platforms
| Platform | Architecture | Status | |---|---|---| | macOS 12+ | arm64 (Apple Silicon) | Supported | | iOS 15+ device | arm64 | Supported | | iOS 15+ Simulator | arm64 (Apple Silicon host) | Supported | | visionOS 1+ | arm64 device + simulator | Supported (v0.167.0+) | | tvOS 15+ | arm64 device + simulator | Supported (v0.167.0+) | | watchOS | — | Out of scope (OCCT static lib too large for watch memory) | | macOS x86_64 (Intel) | — | Out of scope (Apple is winding down Intel macOS support) | | Linux / Windows / Android | — | Under review — see [docs/platform-expansion.md](docs/platform-expansion.md) |
## Building OCCT from Source
The pre-built xcframework is included. To rebuild from source:
```bash ./Scripts/build-occt.sh ```
See [docs/guides/building-occt.md](docs/guides/building-occt.md) for details.
### Prebuilt OCCTBridge (opt-in)
The Objective-C++ bridge (16 files, ~62K lines) compiles from source by default. Consumers who don't need to edit it can opt into a prebuilt binary instead — set `OCCTSWIFT_BRIDGE_PREBUILT=1`. See [docs/guides/prebuilt-bridge.md](docs/guides/prebuilt-bridge.md).
## Documentation
| Document | Description | |----------|-------------| | [Ecosystem](docs/ecosystem.md) | Map of the package family, dependency layering, when to use which | | [SemVer Policy](docs/SEMVER.md) | Versioning rules for the cohort — what triggers MAJOR / MINOR / PATCH | | [Architecture Overview](docs/architecture/overview.md) | Three-layer design, memory management, conventions | | [Adding Features](docs/guides/adding-features.md) | How to wrap new OCCT operations | | [OCCT Concepts](docs/guides/occt-concepts.md) | B-Rep topology, handles, shapes primer | | [Sharing the xcframework](docs/guides/sharing-the-xcframework.md) | Share one local copy across ecosystem repos + the `Package.resolved` pin footgun (#260) | | [Prebuilt OCCTBridge](docs/guides/prebuilt-bridge.md) | Opt-in prebuilt bridge binary (`OCCTSWIFT_BRIDGE_PREBUILT=1`) — skip compiling 62K lines of Obj-C++ per consumer rebuild (#339) | | [API Reference (mapping)](docs/API_REFERENCE.md) | Full operation-by-operation mapping to OCCT classes | | [API Reference (detailed)](docs/reference/) | Per-type function reference — signatures, OCCT mapping, examples (built progressively) | | [Thread Safety](docs/thread-safety.md) | OCCTSerial mutex, parallel execution notes | | [Naming Conventions](docs/naming-conventions.md) | Bridge and Swift naming patterns | | [OCCT Upgrades](docs/occt-upgrades.md) | Breaking changes and migration for each OCCT version | | [Wrapping Status](docs/occtswift-wrapping-gaps.md) | What's wrapped, what's not, and why | | [WebAssembly Plan](docs/wasm-feasibility.md) | Feasibility + phased plan for reusing the API in a SwiftWasm app | | [Changelog](docs/CHANGELOG.md) | Release history |
## License
LGPL-2.1. OpenCASCADE Technology is licensed under LGPL-2.1.
## Acknowledgments
- [OpenCASCADE](https://www.opencascade.com/) for the geometry kernel
## Package Metadata
Repository: secondmouseau/occtswift
Default branch: main
README: README.md