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

# secondmouseau/occtswiftais

High-level **Application Interactive Services** for the OCCTSwift / OCCTSwiftViewport stack — selection-from-topology, manipulator widgets, dimension annotations, and standard scene objects, all in pure Swift.

## What's in the box

- **Selection-from-topology** — pick a body / face / edge / vertex; round-trip the GPU pick to a `TopoDS_Face` / `Edge` / `Vertex` handle on the source `Shape`. Body and face highlights composite via the renderer's per-triangle style buffer (no overlay-mesh flicker). - **Manipulator widgets** — translate and rotate gizmos with `snapTranslate` / `snapRotateDeg`, on the renderer's overlay layer (always-on-top), with native widget pick filtering. SwiftUI integration via `.attachManipulator(_:)`. - **Dimensions** — `LinearDimension`, `AngularDimension`, `RadialDimension`. Topology-aware anchors (vertex / edge midpoint / face bbox center / circular-edge center) feed into OCCTSwiftViewport's existing `MeasurementOverlay` for leader lines + billboarded label. - **Standard scene objects** — `Trihedron`, `WorkPlane`, `Axis`, `PointCloudPresentation`. - **Durable selection identity** — `SubShape` carries a `SubShapeRef` (the resolved `Shape` plus a `BRepGraph.GraphUID` when a graph was in hand at pick time), not just a render-path ordinal. `InteractiveContext.update(_:to:absorbing:operationName:)` absorbs a modelling operation's history into the object's living `BRepGraph`, and `remap(_:using:rebindingTo:)` resolves a pre-mutation `Selection` forward through it — a face split by the operation expands to all its successors; a deleted one is reported via `isDeleted(_:in:)`, never silently pointed at a coincidentally-adjacent neighbour. - **Topology-aware selection filters** — `SurfaceTypeFilter`, `CurveTypeFilter`, `ShapeTypeFilter`, composed with `AllOfFilter` / `AnyOfFilter` / `NotFilter` / `PredicateFilter`, installed via `InteractiveContext.addFilter(_:)` to restrict what's pickable/hoverable beyond `selectionMode`. - **Rectangle and lasso area selection** — `InteractiveContext.selectRectangle(from:to:)` / `selectPolygon(_:)`, honouring `selectionMode` and installed filters; `.attachAreaSelection(_:)` wires up the drag gesture, a live rubber-band/lasso overlay, and camera-orbit passthrough when not actively marqueeing.

[**→ Getting started**](docs/getting-started.md) walks through wiring all of this into a SwiftUI app.

## Installation

```swift .package(url: "https://github.com/SecondMouseAU/OCCTSwiftAIS.git", from: "1.3.0"), ```

`OCCTSwiftAIS` transitively pulls `OCCTSwiftTools`, `OCCTSwiftViewport`, and `OCCTSwift`.

## 30-second example

```swift import SwiftUI import OCCTSwift import OCCTSwiftViewport import OCCTSwiftAIS

@MainActor struct CADView: View {     @StateObject private var ais = InteractiveContext(viewport: ViewportController())

var body: some View {         MetalViewportView(controller: ais.viewport, bodies: $ais.bodies)             .onAppear {                 if let part = Shape.box(width: 10, height: 5, depth: 3) {                     ais.display(part)                 }                 ais.selectionMode = [.face]             }             .onChange(of: ais.selection) { _, sel in                 for face in sel.faces {                     print("selected face area:", face.area())                 }             }     } } ```

## Architecture

``` Application    ↑ OCCTSwiftAIS         ← this repo (selection / manipulator / dimensions)    ↑ OCCTSwiftTools       ← bridge: Shape ↔ ViewportBody    ↑      ↑ OCCTSwift  OCCTSwiftViewport (B-Rep)    (Metal) ```

OCCTSwiftAIS adds **scene-management semantics** an OCCT-style API expects (selection-on-topology, manipulators, dimensions) as a thin Swift layer on top of OCCTSwiftViewport's native Metal renderer. It is **not** a port of OCCT's `TKV3d` / `TKService` / `TKOpenGl` toolkits — see [`OCCTSwift/docs/visualization-research.md`](https://github.com/SecondMouseAU/OCCTSwift/blob/main/docs/visualization-research.md) for why.

## Supported platforms

| Platform | Status | |---|---| | macOS 15+ arm64 | Supported | | iOS 18+ device + simulator arm64 | Supported | | visionOS 1+ device + simulator arm64 | Supported | | tvOS 18+ device + simulator arm64 | Supported |

Same floor as OCCTSwiftViewport.

## Documentation

- [Getting started](docs/getting-started.md) — selection, manipulators, dimensions, standard objects in one walkthrough. - [SPEC.md](SPEC.md) — design rationale and the v0.x → v1.0 trajectory. - [docs/CHANGELOG.md](docs/CHANGELOG.md) — what shipped in each release.

Sibling repos: [OCCTSwift](https://github.com/SecondMouseAU/OCCTSwift) (B-Rep kernel), [OCCTSwiftViewport](https://github.com/SecondMouseAU/OCCTSwiftViewport) (Metal renderer), [OCCTSwiftTools](https://github.com/SecondMouseAU/OCCTSwiftTools) (Shape ↔ ViewportBody bridge).

## License

LGPL 2.1 (matching OCCT). See [LICENSE](LICENSE).

## Package Metadata

Repository: secondmouseau/occtswiftais

Default branch: main

README: README.md