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OCCTSwift

Shape — HLR, Intervals, Mesh Props & Geom Primitives

This page documents the v0.73 / v0.76 batch of Shape-adjacent APIs covering hidden-line removal, interval arithmetic, curve/surface/ray intersection, mesh properties, geometric inertia, and the standalone Geom_* entity wrappers. See the main Shape type page for the primary Shape class (constructors, transforms, booleans, etc.).

Topics

v0.73.0: TKHlr — Extended HLR, ReflectLines, TopCnx, Intrv

HLREdgeCategory

Fine-grained HLR edge categories for exact and polygon-based hidden line removal.

public enum HLREdgeCategory: Int32, Sendable {
    case visibleSharp = 0
    case visibleSmooth = 1
    case visibleSewn = 2
    case visibleOutline = 3
    case visibleIso = 4
    case visibleOutline3d = 5
    case hiddenSharp = 6
    case hiddenSmooth = 7
    case hiddenSewn = 8
    case hiddenOutline = 9
    case hiddenIso = 10
}

Used with hlrEdges(direction:category:) and hlrPolyEdges(direction:category:deflection:) to select which edge class to extract. .visibleIso, .hiddenIso, and .visibleOutline3d are available for exact HLR only.

HLREdgeType

HLR result edge type for the generic CompoundOfEdges and ReflectLines APIs.

public enum HLREdgeType: Int32, Sendable {
    case undefined = 0
    case isoLine = 1
    case outLine = 2
    case rg1Line = 3
    case rgNLine = 4
    case sharp = 5
}

Used with hlrCompoundOfEdges(direction:edgeType:visible:in3d:) and the reflectLinesFiltered family.

hlrEdges(direction:category:)

Extracts edges by fine-grained category using exact HLR (hidden line removal).

public func hlrEdges(direction: SIMD3<Double>, category: HLREdgeCategory) -> Shape?
  • Parameters: direction — view direction vector; category — which class of edges to extract.
  • Returns: Compound of extracted edges, or nil if none exist for that category.
  • OCCT: HLRBRep_Algo / HLRBRep_HLRToShape via OCCTHLRGetEdgesByCategory.
  • Example: 
    if let edges = shape.hlrEdges(direction: SIMD3(0, 0, -1), category: .visibleSharp) {
    // edges is a compound of visible sharp edges in the -Z view
}

hlrPolyEdges(direction:category:deflection:)

Extracts edges by fine-grained category using fast polygon-based (poly) HLR.

public func hlrPolyEdges(direction: SIMD3<Double>, category: HLREdgeCategory,
                         deflection: Double = 0.1) -> Shape?

Poly HLR projects the shape’s triangulation rather than its exact geometry, making it dramatically faster on curved solids (e.g. ~48× on an analytic helicoid). Prefer this for 2D drawings of threaded or curved parts. .visibleIso, .hiddenIso, and .visibleOutline3d are not available for poly HLR.

  • Parameters:
    • direction — view direction vector.
    • category — edge class to extract.
    • deflection — linear mesh deflection (mm) for the internal triangulation. Smaller = finer drawing; larger = coarser and faster. Default 0.1. Meshing is incremental: existing finer triangulations are not coarsened.
  • Returns: Compound of extracted edges, or nil if none exist.
  • OCCT: HLRBRep_PolyAlgo / HLRBRep_PolyHLRToShape via OCCTHLRPolyGetEdgesByCategory.
  • Example: 
    if let vis = shape.hlrPolyEdges(direction: SIMD3(0, 0, -1),
                                 category: .visibleSharp, deflection: 0.05) {
    // vis contains visible sharp edges, finely meshed
}

hlrCompoundOfEdges(direction:edgeType:visible:in3d:)

Extracts a compound of edges using the generic CompoundOfEdges API from exact HLR.

public func hlrCompoundOfEdges(direction: SIMD3<Double>, edgeType: HLREdgeType,
                                visible: Bool, in3d: Bool) -> Shape?
  • Parameters:
    • direction — view direction vector.
    • edgeType — edge type filter (HLREdgeType).
    • visible — true for visible edges, false for hidden.
    • in3d — true to return 3D edges; false for projected 2D edges.
  • Returns: Compound of matching edges, or nil on failure.
  • OCCT: HLRBRep_HLRToShape::CompoundOfEdges via OCCTHLRCompoundOfEdges.
  • Example: 
    if let outlines = shape.hlrCompoundOfEdges(direction: SIMD3(0, 0, -1),
                                            edgeType: .outLine, visible: true, in3d: true) {
    // outlines contains the visible silhouette edges in 3D
}

reflectLines(normal:viewPoint:up:)

Computes reflect (silhouette) lines on a shape for a given view.

public func reflectLines(normal: SIMD3<Double>, viewPoint: SIMD3<Double>,
                         up: SIMD3<Double>) -> Shape?
  • Parameters:
    • normal — view plane normal direction.
    • viewPoint — eye/target position.
    • up — up direction for the view frame.
  • Returns: Compound of reflect line edges in 3D, or nil on failure.
  • OCCT: HLRAppli_ReflectLines via OCCTHLRReflectLines.
  • Example: 
    if let silhouette = shape.reflectLines(normal: SIMD3(0, 0, 1),
                                        viewPoint: SIMD3(0, 0, 100),
                                        up: SIMD3(0, 1, 0)) {
    // silhouette is a compound of outline curves
}

reflectLinesFiltered(normal:viewPoint:up:edgeType:visible:in3d:)

Computes reflect lines and filters the result by edge type and visibility.

public func reflectLinesFiltered(normal: SIMD3<Double>, viewPoint: SIMD3<Double>,
                                  up: SIMD3<Double>, edgeType: HLREdgeType,
                                  visible: Bool, in3d: Bool) -> Shape?
  • Parameters:
    • normal — view plane normal direction.
    • viewPoint — eye/target position.
    • up — up direction.
    • edgeType — edge type to extract.
    • visible — true for visible, false for hidden.
    • in3d — true for 3D edges, false for projected.
  • Returns: Filtered compound of reflect line edges, or nil on failure.
  • OCCT: HLRAppli_ReflectLines / CompoundOfEdges via OCCTHLRReflectLinesFiltered.

EdgeFaceTransitionResult

Result of an edge-face transition computation.

public struct EdgeFaceTransitionResult: Sendable {
    public let transition: Int           // TopAbs_Orientation: 0=FORWARD, 1=REVERSED, 2=INTERNAL, 3=EXTERNAL
    public let boundaryTransition: Int   // TopAbs_Orientation for boundary
}

FaceInterference

Face interference description passed to edgeFaceTransition(edgeTangent:edgeNormal:edgeCurvature:faces:).

public struct FaceInterference: Sendable {
    public let tangent: SIMD3<Double>
    public let normal: SIMD3<Double>
    public let curvature: Double
    public let orientation: Int32        // TopAbs_Orientation
    public let transition: Int32         // TopAbs_Orientation
    public let boundaryTransition: Int32 // TopAbs_Orientation
    public let tolerance: Double

    public init(tangent: SIMD3<Double>, normal: SIMD3<Double>, curvature: Double,
                orientation: Int32, transition: Int32, boundaryTransition: Int32,
                tolerance: Double)
}

Shape.edgeFaceTransition(edgeTangent:edgeNormal:edgeCurvature:faces:)

Computes the cumulated edge-face transition orientation for multiple face interferences on an edge.

public static func edgeFaceTransition(edgeTangent: SIMD3<Double>,
                                      edgeNormal: SIMD3<Double>,
                                      edgeCurvature: Double,
                                      faces: [FaceInterference]) -> EdgeFaceTransitionResult
  • Parameters:
    • edgeTangent — edge tangent direction.
    • edgeNormal — edge normal direction (use .zero for linear edges).
    • edgeCurvature — edge curvature (0 for linear edges).
    • faces — array of FaceInterference descriptors.
  • Returns: EdgeFaceTransitionResult with cumulated transition and boundaryTransition orientations.
  • OCCT: TopCnx_EdgeFaceTransition via OCCTTopCnxEdgeFaceTransition.

Intrv_Interval (Interval with Tolerances)

Interval

A real interval [start, end] with optional per-endpoint tolerances, wrapping Intrv_Interval.

public final class Interval: @unchecked Sendable

Interval.init(start:end:tolStart:tolEnd:)

Creates an interval with bounds and optional tolerances.

public init(start: Double, end: Double, tolStart: Float = 0, tolEnd: Float = 0)
  • Parameters: start — lower bound; end — upper bound; tolStart — tolerance at start; tolEnd — tolerance at end.
  • OCCT: Intrv_Interval(start, end, tolStart, tolEnd) via OCCTIntrvIntervalCreate.
  • Example: 
    let iv = Interval(start: 0.0, end: 1.0, tolStart: 1e-6, tolEnd: 1e-6)

Interval.Bounds

The bounds and tolerances of an interval.

public struct Bounds: Sendable {
    public let start: Double
    public let end: Double
    public let tolStart: Float
    public let tolEnd: Float
}

bounds

Gets the interval bounds and tolerances.

public var bounds: Bounds { get }
  • Returns: Bounds struct with start, end, tolStart, tolEnd.
  • OCCT: Intrv_Interval::Start, End, TolStart, TolEnd via OCCTIntrvIntervalBounds.

isProbablyEmpty

Whether the interval is probably empty.

public var isProbablyEmpty: Bool { get }
  • Returns: true if start + tolStart > end - tolEnd.
  • OCCT: Intrv_Interval::IsVoid via OCCTIntrvIntervalIsProbablyEmpty.

position(relativeTo:)

Position of this interval relative to another.

public func position(relativeTo other: Interval) -> Int
  • Parameters: other — the reference interval.
  • Returns: Intrv_Position enum raw value (0 = Before … 12 = After).
  • OCCT: Intrv_Interval::Position via OCCTIntrvIntervalPosition.

isBefore(_:)

Whether this interval is entirely before another.

public func isBefore(_ other: Interval) -> Bool
  • OCCT: Intrv_Interval::IsBefore via OCCTIntrvIntervalIsBefore.

isAfter(_:)

Whether this interval is entirely after another.

public func isAfter(_ other: Interval) -> Bool
  • OCCT: Intrv_Interval::IsAfter via OCCTIntrvIntervalIsAfter.

isInside(_:)

Whether this interval is entirely inside another.

public func isInside(_ other: Interval) -> Bool
  • OCCT: Intrv_Interval::IsInside via OCCTIntrvIntervalIsInside.

isEnclosing(_:)

Whether this interval entirely encloses another.

public func isEnclosing(_ other: Interval) -> Bool
  • OCCT: Intrv_Interval::IsEnclosing via OCCTIntrvIntervalIsEnclosing.

isSimilar(to:)

Whether this interval has the same bounds as another (within tolerances).

public func isSimilar(to other: Interval) -> Bool
  • OCCT: Intrv_Interval::IsSimilar via OCCTIntrvIntervalIsSimilar.

setStart(_:tolerance:)

Sets the start bound.

public func setStart(_ start: Double, tolerance: Float = 0)
  • Parameters: start — new start value; tolerance — new start tolerance.
  • OCCT: Intrv_Interval::SetStart via OCCTIntrvIntervalSetStart.

setEnd(_:tolerance:)

Sets the end bound.

public func setEnd(_ end: Double, tolerance: Float = 0)
  • Parameters: end — new end value; tolerance — new end tolerance.
  • OCCT: Intrv_Interval::SetEnd via OCCTIntrvIntervalSetEnd.

fuseAtStart(_:tolerance:)

Extends the start bound outward (union at start).

public func fuseAtStart(_ start: Double, tolerance: Float = 0)
  • Parameters: start — new start bound (must be ≤ current start to extend); tolerance — new tolerance.
  • OCCT: Intrv_Interval::FuseAtStart via OCCTIntrvIntervalFuseAtStart.

fuseAtEnd(_:tolerance:)

Extends the end bound outward (union at end).

public func fuseAtEnd(_ end: Double, tolerance: Float = 0)
  • OCCT: Intrv_Interval::FuseAtEnd via OCCTIntrvIntervalFuseAtEnd.

cutAtStart(_:tolerance:)

Trims the start bound inward.

public func cutAtStart(_ start: Double, tolerance: Float = 0)
  • OCCT: Intrv_Interval::CutAtStart via OCCTIntrvIntervalCutAtStart.

cutAtEnd(_:tolerance:)

Trims the end bound inward.

public func cutAtEnd(_ end: Double, tolerance: Float = 0)
  • OCCT: Intrv_Interval::CutAtEnd via OCCTIntrvIntervalCutAtEnd.

Intrv_Intervals (Sorted Non-Overlapping Interval Sequence)

IntervalSet

A sorted sequence of non-overlapping Intrv_Interval objects supporting set-theoretic operations.

public final class IntervalSet: @unchecked Sendable

IntervalSet.init(start:end:)

Creates an interval set containing a single interval.

public init(start: Double, end: Double)
  • OCCT: Intrv_Intervals(Intrv_Interval) via OCCTIntrvIntervalsCreate.
  • Example: 
    let set = IntervalSet(start: 0.0, end: 10.0)

IntervalSet.init()

Creates an empty interval set.

public init()
  • OCCT: Intrv_Intervals() via OCCTIntrvIntervalsCreateEmpty.

count

Number of non-overlapping intervals in the set.

public var count: Int { get }
  • OCCT: Intrv_Intervals::Length via OCCTIntrvIntervalsCount.

bounds(at:)

Gets the bounds of the interval at a zero-based index.

public func bounds(at index: Int) -> Interval.Bounds
  • Parameters: index — zero-based interval index (internally maps to 1-based OCCT indexing).
  • Returns: Interval.Bounds for that interval.
  • OCCT: Intrv_Intervals::Value via OCCTIntrvIntervalsValue.

unite(start:end:)

Adds an interval to the set (union).

public func unite(start: Double, end: Double)
  • OCCT: Intrv_Intervals::Unite via OCCTIntrvIntervalsUnite.
  • Example: 
    let set = IntervalSet(start: 0.0, end: 5.0)
set.unite(start: 7.0, end: 10.0)
// set now has two intervals: [0,5] and [7,10]

subtract(start:end:)

Subtracts an interval from the set.

public func subtract(start: Double, end: Double)
  • OCCT: Intrv_Intervals::Subtract via OCCTIntrvIntervalsSubtract.

intersect(start:end:)

Intersects the set with an interval, keeping only the overlap.

public func intersect(start: Double, end: Double)
  • OCCT: Intrv_Intervals::Intersect via OCCTIntrvIntervalsIntersect.

xUnite(start:end:)

Applies exclusive union (symmetric difference) with an interval.

public func xUnite(start: Double, end: Double)
  • OCCT: Intrv_Intervals::XUnite via OCCTIntrvIntervalsXUnite.

ShapeRayIntersection (BRepIntCurveSurface_Inter)

ShapeRayIntersection

Iterator over line/curve–shape intersection results, wrapping BRepIntCurveSurface_Inter.

public final class ShapeRayIntersection: @unchecked Sendable

ShapeRayIntersection.Hit

A single intersection hit between the line/curve and a face.

public struct Hit {
    public let x: Double, y: Double, z: Double  // 3D intersection point
    public let u: Double, v: Double              // UV parameters on face surface
    public let w: Double                         // parameter on the curve/line
}

ShapeRayIntersection.init?(shape:originX:originY:originZ:dirX:dirY:dirZ:tolerance:)

Creates an intersection of a line with a shape.

public init?(shape: Shape, originX: Double, originY: Double, originZ: Double,
             dirX: Double, dirY: Double, dirZ: Double, tolerance: Double = 1e-6)
  • Parameters: shape — target B-Rep shape; originX/Y/Z — ray origin; dirX/Y/Z — ray direction; tolerance — intersection tolerance.
  • Returns: nil if initialisation fails.
  • OCCT: BRepIntCurveSurface_Inter::Init(shape, gp_Lin) via OCCTCurveSurfaceInterCreateLine.
  • Example: 
    if let inter = ShapeRayIntersection(shape: box,
                                     originX: 0, originY: 0, originZ: -10,
                                     dirX: 0, dirY: 0, dirZ: 1) {
    let hits = inter.allHits()
}

ShapeRayIntersection.init?(shape:curve:tolerance:)

Creates an intersection of a Curve3D with a shape.

public init?(shape: Shape, curve: Curve3D, tolerance: Double = 1e-6)
  • Parameters: shape — target shape; curve — 3D curve; tolerance — intersection tolerance.
  • Returns: nil if initialisation fails.
  • OCCT: BRepIntCurveSurface_Inter::Init(shape, curve) via OCCTCurveSurfaceInterCreateCurve.

hasMore

Whether more intersection results are available for iteration.

public var hasMore: Bool { get }
  • OCCT: BRepIntCurveSurface_Inter::More via OCCTCurveSurfaceInterMore.

next()

Advances to the next intersection result.

public func next()
  • OCCT: BRepIntCurveSurface_Inter::Next via OCCTCurveSurfaceInterNext.

currentHit

Returns the current intersection hit data.

public var currentHit: Hit { get }
  • Returns: Hit with 3D point, UV face parameters, and curve parameter w.
  • OCCT: BRepIntCurveSurface_Inter::Pnt, UParameter, VParameter, WParameter via OCCTCurveSurfaceInterHit.

currentFace

Returns the face at the current intersection.

public var currentFace: Face? { get }
  • Returns: The Face that was hit, or nil on failure.
  • OCCT: BRepIntCurveSurface_Inter::Face via OCCTCurveSurfaceInterFace.

allHits()

Collects all intersection hits by draining the iterator.

public func allHits() -> [Hit]
  • Returns: Array of all Hit values (may be empty if no intersections).
  • Note: Calling this exhausts the iterator — hasMore will be false afterward.
  • Example: 
    if let inter = ShapeRayIntersection(shape: shape,
                                     originX: 0, originY: 0, originZ: 50,
                                     dirX: 0, dirY: 0, dirZ: -1) {
    for hit in inter.allHits() {
        print("hit at z=\(hit.z), u=\(hit.u), v=\(hit.v)")
    }
}

ShapeConstruct (Triangulation)

Shape.triangulationFromPoints(_:)

Creates a triangulated face from a flat list of 3D points.

public static func triangulationFromPoints(_ points: [(Double, Double, Double)]) -> Shape?
  • Parameters: points — ordered list of 3D coordinate triples.
  • Returns: A triangulated Shape (face), or nil on failure.
  • OCCT: ShapeConstruct_MakeTriangulation via OCCTShapeConstructTriangulationFromPoints.
  • Example: 
    let pts = [(0.0, 0.0, 0.0), (1.0, 0.0, 0.0), (0.5, 1.0, 0.0)]
if let tri = Shape.triangulationFromPoints(pts) {
    // tri is a triangulated face
}

Shape.triangulationFromWire(_:)

Creates a triangulated face from a planar wire.

public static func triangulationFromWire(_ wire: Wire) -> Shape?
  • Parameters: wire — a closed planar wire to triangulate.
  • Returns: A triangulated Shape, or nil on failure.
  • OCCT: ShapeConstruct_MakeTriangulation via OCCTShapeConstructTriangulationFromWire.
  • Example: 
    if let rect = Wire.rectangle(width: 10, height: 5),
   let tri = Shape.triangulationFromWire(rect) {
    // tri is a mesh of the rectangle
}

Surface Extensions (ShapeCustom_Surface periodic + gap)

Surface.convertToPeriodic()

Converts a surface to periodic form.

public func convertToPeriodic() -> Surface?
  • Returns: The periodified surface, or nil if the surface is already periodic or cannot be converted.
  • OCCT: ShapeCustom_Surface::ConvertToPeriodic via OCCTSurfaceConvertToPeriodic.
  • Example: 
    if let periodic = surface.convertToPeriodic() {
    print(periodic.isUPeriodic)  // true for converted cylinder/cone
}

conversionGap

The distance between the original and periodically converted surface (conversion error).

public var conversionGap: Double { get }
  • Returns: Gap value in model units; 0.0 if no conversion has been applied.
  • OCCT: ShapeCustom_Surface::Gap via OCCTSurfaceConversionGap.

MeshCinert (Linear Mass Properties from Mesh)

MeshCinertResult

Result of linear mass property computation from polygon points.

public struct MeshCinertResult {
    public let mass: Double
    public let centerX: Double, centerY: Double, centerZ: Double
}

Edge.meshPolygonPoints()

Prepares polygon points from a meshed edge for use with meshCinertCompute(points:).

public func meshPolygonPoints() -> [(Double, Double, Double)]
  • Returns: Array of 3D coordinate triples from the edge’s mesh polygon (up to 1000 points).
  • OCCT: BRepGProp_MeshCinert::PreparePolygon via OCCTMeshCinertPreparePolygon.
  • Example: 
    let pts = someEdge.meshPolygonPoints()
let props = meshCinertCompute(points: pts)

meshCinertCompute(points:)

Computes linear mass properties (mass and centre of mass) from polygon point coordinates.

public func meshCinertCompute(points: [(Double, Double, Double)]) -> MeshCinertResult

This is a free function (not a method). Feed it the output of Edge.meshPolygonPoints().

  • Parameters: points — array of 3D coordinate triples.
  • Returns: MeshCinertResult with mass (total arc length) and centre coordinates.
  • OCCT: BRepGProp_MeshCinert::Perform via OCCTMeshCinertCompute.

MeshProps (Surface/Volume Properties from Mesh)

MeshPropsType

Selects the type of mesh property to compute.

public enum MeshPropsType {
    case volume
    case surface
}

MeshPropsResult

Result of mesh property computation.

public struct MeshPropsResult {
    public let mass: Double
    public let centerX: Double, centerY: Double, centerZ: Double
}

mass is surface area when type == .surface, or enclosed volume when type == .volume.

Face.meshProps(type:)

Computes mesh surface or volume properties for a triangulated face.

public func meshProps(type: MeshPropsType) -> MeshPropsResult
  • Parameters: type — .surface for area and centroid, .volume for enclosed volume and centroid.
  • Returns: MeshPropsResult with mass and centre of mass.
  • OCCT: BRepGProp_MeshProps (Sinert/Vinert path) via OCCTMeshPropsCompute.
  • Example: 
    let result = triangulatedFace.meshProps(type: .surface)
print("area =", result.mass)

MeshShapeTool (Static Mesh Utilities)

Face.maxMeshTolerance

Maximum tolerance of edges and vertices on this face.

public var maxMeshTolerance: Double { get }
  • Returns: Maximum tolerance in model units.
  • OCCT: BRepMesh_ShapeTool::MaxFaceTolerance via OCCTMeshShapeToolMaxFaceTolerance.

Face.uvPoints(edge:)

Gets the UV parameter points of an edge on this face.

public func uvPoints(edge: Edge) -> (u1: Double, v1: Double, u2: Double, v2: Double)?
  • Parameters: edge — an edge that lies on this face.
  • Returns: Tuple of UV parameters at each end of the edge, or nil if the edge is not on this face.
  • OCCT: BRepMesh_ShapeTool::UVPoints via OCCTMeshShapeToolUVPoints.
  • Example: 
    if let uv = face.uvPoints(edge: edge) {
    print("start UV: (\(uv.u1), \(uv.v1))")
}

Shape.meshMaxDimension

Maximum dimension of this shape’s bounding box (useful for mesh sizing heuristics).

public var meshMaxDimension: Double { get }
  • Returns: The largest of the bounding box width, height, and depth.
  • OCCT: BRepMesh_ShapeTool::BoxMaxDimension via OCCTMeshShapeToolBoxMaxDimension.

ValidateEdge (BRepLib_ValidateEdge)

ValidateEdgeResult

Result of 3D curve vs curve-on-surface consistency check.

public struct ValidateEdgeResult {
    public let isDone: Bool
    public let isWithinTolerance: Bool
    public let maxDistance: Double
    public let tolerance: Double
}

Edge.validate(on:tolerance:)

Validates edge geometry against a face (3D curve vs curve-on-surface consistency).

public func validate(on face: Face, tolerance: Double = 1e-3) -> ValidateEdgeResult
  • Parameters: face — the face containing this edge’s pcurve; tolerance — acceptable maximum deviation.
  • Returns: ValidateEdgeResult with isDone, isWithinTolerance, maxDistance, and the tested tolerance.
  • OCCT: BRepLib_ValidateEdge via OCCTValidateEdge.
  • Example: 
    let result = edge.validate(on: face)
if !result.isWithinTolerance {
    print("max deviation:", result.maxDistance)
}

BiTgte_Blend (Rolling-Ball Blend)

Shape.biTgteBlend(edgeIndices:radius:tolerance:nubs:)

Creates a rolling-ball blend on specified edges using BiTgte_Blend.

public func biTgteBlend(edgeIndices: [Int], radius: Double, tolerance: Double = 1e-3,
                        nubs: Bool = false) -> Shape?

BiTgte_Blend is an alternative blend algorithm that can handle configurations where BRepFilletAPI_MakeFillet fails.

  • Parameters:
    • edgeIndices — zero-based indices of edges to blend (as returned by the shape’s topology explorer).
    • radius — blend radius.
    • tolerance — geometric tolerance.
    • nubs — if true, outputs NUBS (Non-Uniform B-Spline) surfaces; if false, outputs NURBS.
  • Returns: Blended shape, or nil if blending fails.
  • OCCT: BiTgte_Blend::Perform via OCCTBiTgteBlend.
  • Example: 
    if let blended = box.biTgteBlend(edgeIndices: [0, 1, 2], radius: 2.0) {
    // blended has rounded edges
}

GeomConvert_ApproxCurve/Surface

ApproxContinuity

Continuity level for BSpline approximation.

public enum ApproxContinuity: Int32 {
    case c0 = 0, c1 = 1, c2 = 2, c3 = 3
}

ApproxCurveResult

Result of curve approximation including the output curve, error, and status.

public struct ApproxCurveResult {
    public let curve: Curve3D?
    public let maxError: Double
    public let isDone: Bool
    public let hasResult: Bool
}

Curve3D.approxWithDetails(tolerance:continuity:maxSegments:maxDegree:)

Approximates a 3D curve as a BSpline with detailed result information.

public func approxWithDetails(tolerance: Double, continuity: ApproxContinuity = .c2,
                               maxSegments: Int = 100, maxDegree: Int = 8) -> ApproxCurveResult
  • Parameters:
    • tolerance — maximum approximation deviation.
    • continuity — desired continuity of the output BSpline.
    • maxSegments — maximum number of BSpline segments.
    • maxDegree — maximum polynomial degree.
  • Returns: ApproxCurveResult with the output Curve3D (or nil), maxError, and status flags.
  • OCCT: GeomConvert_ApproxCurve via OCCTGeomConvertApproxCurve.
  • Example: 
    let result = curve.approxWithDetails(tolerance: 0.01, continuity: .c2)
if result.isDone, let bsp = result.curve {
    print("max error:", result.maxError)
}

ApproxSurfaceResult

Result of surface approximation including the output surface, error, and status.

public struct ApproxSurfaceResult {
    public let surface: Surface?
    public let maxError: Double
    public let isDone: Bool
    public let hasResult: Bool
}

Surface.approxWithDetails(tolerance:uContinuity:vContinuity:maxDegree:maxSegments:)

Approximates a surface as a BSpline with detailed result information.

public func approxWithDetails(tolerance: Double, uContinuity: ApproxContinuity = .c1,
                               vContinuity: ApproxContinuity = .c1,
                               maxDegree: Int = 8, maxSegments: Int = 100) -> ApproxSurfaceResult
  • Parameters:
    • tolerance — maximum approximation deviation.
    • uContinuity — desired continuity in U direction.
    • vContinuity — desired continuity in V direction.
    • maxDegree — maximum polynomial degree.
    • maxSegments — maximum number of BSpline segments.
  • Returns: ApproxSurfaceResult with the output Surface (or nil), maxError, and status flags.
  • OCCT: GeomConvert_ApproxSurface via OCCTGeomConvertApproxSurface.
  • Note: Prefer Surface.approximated(tolerance:continuity:maxSegments:maxDegree:) for simpler use; use this variant when you need the error and status separately.
  • Example: 
    let result = surface.approxWithDetails(tolerance: 0.001)
if result.isDone, let bsp = result.surface {
    print("max error:", result.maxError)
}

GCPnts_QuasiUniformAbscissa

Edge.quasiUniformParameters(count:)

Computes a quasi-uniform parameter distribution along an edge.

public func quasiUniformParameters(count: Int) -> [Double]

The returned parameters are distributed so that the chord lengths between consecutive curve points are approximately equal.

  • Parameters: count — desired number of parameter values.
  • Returns: Array of curve parameters of length ≤ count.
  • OCCT: GCPnts_QuasiUniformAbscissa via OCCTGCPntsQuasiUniform.
  • Example: 
    let params = edge.quasiUniformParameters(count: 20)
// params has ~20 evenly-spaced (by chord) parameter values

GCPnts_TangentialDeflection

TangentialDeflectionPoint

A sampled point from tangential deflection discretisation.

public struct TangentialDeflectionPoint {
    public let parameter: Double
    public let x: Double, y: Double, z: Double
}

Edge.tangentialDeflectionPoints(angularDeflection:curvatureDeflection:minPoints:)

Samples an edge using combined angular and chordal deflection criteria.

public func tangentialDeflectionPoints(angularDeflection: Double = 0.1,
                                       curvatureDeflection: Double = 0.1,
                                       minPoints: Int = 2) -> [TangentialDeflectionPoint]

This is the standard adaptive sampling algorithm used by OCCT’s meshing pipeline; it produces denser samples where curvature is high.

  • Parameters:
    • angularDeflection — maximum angular deviation between consecutive tangents (radians).
    • curvatureDeflection — maximum chordal deviation (model units).
    • minPoints — minimum number of sample points (must be ≥ 2).
  • Returns: Array of TangentialDeflectionPoint values (up to 10000).
  • OCCT: GCPnts_TangentialDeflection via OCCTGCPntsTangentialDeflection.
  • Example: 
    let pts = edge.tangentialDeflectionPoints(angularDeflection: 0.05,
                                           curvatureDeflection: 0.1)
for pt in pts {
    print("t=\(pt.parameter): (\(pt.x), \(pt.y), \(pt.z))")
}

BRepGProp_Cinert (Curve Inertia per Edge)

CurveInertia

Curve linear inertia properties (arc length and centre of mass).

public struct CurveInertia {
    public let length: Double
    public let centerX: Double, centerY: Double, centerZ: Double
}

Edge.curveInertia

Computes linear inertia (arc length and centre of mass) for this edge.

public var curveInertia: CurveInertia { get }
  • Returns: CurveInertia with length and centre of mass coordinates.
  • OCCT: BRepGProp_Cinert via OCCTBRepGPropCinert.
  • Example: 
    let inertia = edge.curveInertia
print("length:", inertia.length)
print("center:", inertia.centerX, inertia.centerY, inertia.centerZ)

BRepGProp_Sinert (Surface Inertia per Face)

FaceSurfaceInertia

Face surface inertia properties (area and centre of mass).

public struct FaceSurfaceInertia {
    public let area: Double
    public let centerX: Double, centerY: Double, centerZ: Double
    public let epsilon: Double
}

epsilon is the integration error bound; it is 0 for the non-adaptive overload.

Face.surfaceInertia

Computes surface inertia (area and centre of mass) for this face.

public var surfaceInertia: FaceSurfaceInertia { get }
  • Returns: FaceSurfaceInertia with area and centre of mass (epsilon = 0).
  • OCCT: BRepGProp_Sinert via OCCTBRepGPropSinert.
  • Example: 
    let inertia = face.surfaceInertia
print("area:", inertia.area)

Face.surfaceInertia(epsilon:)

Computes surface inertia using adaptive numerical integration to the given error bound.

public func surfaceInertia(epsilon: Double) -> FaceSurfaceInertia
  • Parameters: epsilon — target integration error bound.
  • Returns: FaceSurfaceInertia with area, centre of mass, and actual epsilon achieved.
  • OCCT: BRepGProp_Sinert adaptive overload via OCCTBRepGPropSinertAdaptive.

BRepGProp_Vinert (Volume Inertia per Face)

FaceVolumeInertia

Face volume inertia contribution.

public struct FaceVolumeInertia {
    public let volume: Double
    public let centerX: Double, centerY: Double, centerZ: Double
}

Face.volumeInertia

Computes the volume inertia contribution from this face (relative to the origin).

public var volumeInertia: FaceVolumeInertia { get }
  • Returns: FaceVolumeInertia with signed volume and centre of mass.
  • OCCT: BRepGProp_Vinert via OCCTBRepGPropVinert.
  • Example: 
    let vi = face.volumeInertia
print("volume contribution:", vi.volume)

Face.volumeInertia(planeNormal:planeDistance:)

Computes volume inertia with respect to a reference plane.

public func volumeInertia(planeNormal: SIMD3<Double>, planeDistance: Double = 0) -> FaceVolumeInertia
  • Parameters:
    • planeNormal — normal of the reference plane.
    • planeDistance — signed distance from origin to the plane along planeNormal.
  • Returns: FaceVolumeInertia measured relative to the given plane.
  • OCCT: BRepGProp_Vinert(face, gp_Pln) via OCCTBRepGPropVinertPlane.

ShapeConstruct_ProjectCurveOnSurface

Curve3D.projectOnSurface(_:firstParam:lastParam:precision:)

Projects a 3D curve onto a surface, returning a 2D (UV) curve.

public func projectOnSurface(_ surface: Surface, firstParam: Double? = nil,
                              lastParam: Double? = nil, precision: Double = 1e-6) -> Curve2D?
  • Parameters:
    • surface — target surface.
    • firstParam — start of the curve parameter range (default: domain.lowerBound).
    • lastParam — end of the curve parameter range (default: domain.upperBound).
    • precision — projection tolerance.
  • Returns: A Curve2D in UV parameter space of the surface, or nil if projection fails.
  • OCCT: ShapeConstruct_ProjectCurveOnSurface::Perform via OCCTProjectCurveOnSurface.
  • Example: 
    if let pcurve = curve3D.projectOnSurface(surface, precision: 1e-6) {
    // pcurve is the 2D UV representation of curve3D on surface
}

BRepPreviewAPI_MakeBox

Shape.previewBox(width:height:depth:)

Creates a preview box shape that handles degenerate dimensions gracefully.

public static func previewBox(width: Double, height: Double, depth: Double) -> Shape?

Unlike Shape.box(width:height:depth:), this factory accepts degenerate inputs and returns the appropriate lower-dimensional shape: a box for fully 3D dimensions, a face for one zero dimension, an edge for two zero dimensions, or a vertex for all-zero dimensions.

  • Parameters: width — X dimension; height — Y dimension; depth — Z dimension.
  • Returns: A Shape (solid, face, edge, or vertex), or nil on failure.
  • OCCT: BRepPreviewAPI_MakeBox via OCCTPreviewBox.
  • Example: 
    // Returns a Face (sheet) when depth is 0
if let sheet = Shape.previewBox(width: 10, height: 5, depth: 0) {
    print(sheet.shapeType)  // .face
}

GeomPoint3D (Geom_CartesianPoint)

GeomPoint3D

A Handle-managed 3D geometric point, wrapping Geom_CartesianPoint.

public final class GeomPoint3D: @unchecked Sendable

Useful when you need OCCT’s geometry-level point entity (rather than a raw SIMD3<Double>) for operations that take Handle(Geom_Point) arguments.

GeomPoint3D.init(x:y:z:)

Creates a geometric point at the given coordinates.

public init(x: Double, y: Double, z: Double)
  • OCCT: Geom_CartesianPoint(x, y, z) via OCCTGeomPoint3DCreate.

GeomPoint3D.init(simd:)

Creates a geometric point from a SIMD3<Double>.

public init(simd: SIMD3<Double>)

x, y, z

The Cartesian coordinates of this point.

public var x: Double { get }
public var y: Double { get }
public var z: Double { get }
  • OCCT: Geom_CartesianPoint::X, Y, Z.

coordinates

The coordinates as a SIMD3<Double>.

public var coordinates: SIMD3<Double> { get }

setCoordinates(x:y:z:)

Sets the point coordinates.

public func setCoordinates(x: Double, y: Double, z: Double)
  • OCCT: Geom_CartesianPoint::SetCoord via OCCTGeomPoint3DSetCoord.

distance(to:)

Returns the Euclidean distance to another geometric point.

public func distance(to other: GeomPoint3D) -> Double
  • OCCT: Geom_Point::Distance via OCCTGeomPoint3DDistance.
  • Example: 
    let a = GeomPoint3D(x: 0, y: 0, z: 0)
let b = GeomPoint3D(x: 3, y: 4, z: 0)
print(a.distance(to: b))  // 5.0

squareDistance(to:)

Returns the squared Euclidean distance to another geometric point.

public func squareDistance(to other: GeomPoint3D) -> Double
  • OCCT: Geom_Point::SquareDistance via OCCTGeomPoint3DSquareDistance.

translate(dx:dy:dz:)

Translates this point in place.

public func translate(dx: Double, dy: Double, dz: Double)
  • OCCT: Geom_CartesianPoint::Translate(gp_Vec) via OCCTGeomPoint3DTranslate.

GeomDirection (Geom_Direction)

GeomDirection

A Handle-managed 3D unit vector (always normalised), wrapping Geom_Direction.

public final class GeomDirection: @unchecked Sendable

The input vector is automatically normalised on construction. Use this when downstream OCCT APIs require a Handle(Geom_Direction).

GeomDirection.init(x:y:z:)

Creates a unit direction from component values. The vector is normalised automatically.

public init(x: Double, y: Double, z: Double)
  • OCCT: Geom_Direction(x, y, z) via OCCTGeomDirectionCreate.
  • Example: 
    let up = GeomDirection(x: 0, y: 0, z: 1)

GeomDirection.init(simd:)

Creates a unit direction from a SIMD3<Double>.

public init(simd: SIMD3<Double>)

coordinates

The unit vector as a SIMD3<Double>.

public var coordinates: SIMD3<Double> { get }
  • OCCT: Geom_Direction::X, Y, Z via OCCTGeomDirectionCoords.

setCoordinates(x:y:z:)

Sets the direction; the new vector is automatically normalised.

public func setCoordinates(x: Double, y: Double, z: Double)
  • OCCT: Geom_Direction::SetCoord via OCCTGeomDirectionSetCoord.

crossed(with:)

Returns the cross product with another direction.

public func crossed(with other: GeomDirection) -> GeomDirection?
  • Returns: A new GeomDirection perpendicular to both, or nil if the vectors are parallel (cross product is zero).
  • OCCT: Geom_Direction::Cross via OCCTGeomDirectionCrossed.
  • Example: 
    let x = GeomDirection(x: 1, y: 0, z: 0)
let y = GeomDirection(x: 0, y: 1, z: 0)
if let z = x.crossed(with: y) {
    print(z.coordinates)  // SIMD3(0, 0, 1)
}

GeomVector3D (Geom_VectorWithMagnitude)

GeomVector3D

A Handle-managed 3D vector with arbitrary magnitude, wrapping Geom_VectorWithMagnitude. Unlike GeomDirection, the vector may have any non-negative length including zero.

public final class GeomVector3D: @unchecked Sendable

GeomVector3D.init(x:y:z:)

Creates a vector from component values.

public init(x: Double, y: Double, z: Double)
  • OCCT: Geom_VectorWithMagnitude(x, y, z) via OCCTGeomVector3DCreate.

GeomVector3D.init(simd:)

Creates a vector from a SIMD3<Double>.

public init(simd: SIMD3<Double>)

GeomVector3D.init(from:to:)

Creates a vector from point p1 to point p2.

public init(from p1: SIMD3<Double>, to p2: SIMD3<Double>)
  • OCCT: Geom_VectorWithMagnitude(p1, p2) via OCCTGeomVector3DFromPoints.
  • Example: 
    let v = GeomVector3D(from: SIMD3(0, 0, 0), to: SIMD3(3, 4, 0))
print(v.magnitude)  // 5.0

coordinates

The vector components as a SIMD3<Double>.

public var coordinates: SIMD3<Double> { get }
  • OCCT: Geom_Vector::X, Y, Z via OCCTGeomVector3DCoords.

magnitude

The Euclidean length of this vector.

public var magnitude: Double { get }
  • OCCT: Geom_Vector::Magnitude via OCCTGeomVector3DMagnitude.

dot(_:)

Dot product with another vector.

public func dot(_ other: GeomVector3D) -> Double
  • OCCT: Geom_Vector::Dot via OCCTGeomVector3DDot.

added(_:)

Returns the sum of this vector and another.

public func added(_ other: GeomVector3D) -> GeomVector3D
  • OCCT: Geom_Vector::Added via OCCTGeomVector3DAdded.

multiplied(by:)

Returns this vector scaled by a scalar.

public func multiplied(by scalar: Double) -> GeomVector3D
  • OCCT: Geom_VectorWithMagnitude::Multiplied via OCCTGeomVector3DMultiplied.

normalized()

Returns a normalised copy of this vector.

public func normalized() -> GeomVector3D?
  • Returns: Unit vector in the same direction, or nil if magnitude is near zero.
  • OCCT: Geom_VectorWithMagnitude::Normalized via OCCTGeomVector3DNormalized.
  • Example: 
    let v = GeomVector3D(x: 3, y: 4, z: 0)
if let u = v.normalized() {
    print(u.magnitude)  // ~1.0
}

crossed(_:)

Returns the cross product with another vector.

public func crossed(_ other: GeomVector3D) -> GeomVector3D
  • Returns: A new GeomVector3D perpendicular to both inputs.
  • OCCT: Geom_VectorWithMagnitude::Crossed via OCCTGeomVector3DCrossed.

Axis1Placement (Geom_Axis1Placement)

Axis1Placement

A Handle-managed 3D axis (origin point + direction), wrapping Geom_Axis1Placement. Used as a placement entity for geometry operations that require an Axis1.

public final class Axis1Placement: @unchecked Sendable

Axis1Placement.init(origin:direction:)

Creates an axis placement from an origin point and a direction vector.

public init(origin: SIMD3<Double>, direction: SIMD3<Double>)
  • Parameters: origin — the axis origin point; direction — the axis direction (normalised internally).
  • OCCT: Geom_Axis1Placement(gp_Pnt, gp_Dir) via OCCTAxis1PlacementCreate.
  • Example: 
    let axis = Axis1Placement(origin: .zero, direction: SIMD3(0, 0, 1))

location

The origin point of the axis.

public var location: SIMD3<Double> { get }
  • OCCT: Geom_Axis1Placement::Location via OCCTAxis1PlacementLocation.

direction

The unit direction of the axis.

public var direction: SIMD3<Double> { get }
  • OCCT: Geom_Axis1Placement::Direction via OCCTAxis1PlacementDirection.

reverse()

Reverses the axis direction in place.

public func reverse()
  • OCCT: Geom_Axis1Placement::Reverse via OCCTAxis1PlacementReverse.

reversed()

Returns a new axis with the direction reversed.

public func reversed() -> Axis1Placement
  • Returns: A new Axis1Placement with the same origin and the direction negated.
  • OCCT: Geom_Axis1Placement::Reversed via OCCTAxis1PlacementReversed.
  • Example: 
    let axis = Axis1Placement(origin: .zero, direction: SIMD3(0, 0, 1))
let flipped = axis.reversed()
print(flipped.direction)  // SIMD3(0, 0, -1)

setDirection(_:)

Sets the axis direction.

public func setDirection(_ dir: SIMD3<Double>)
  • OCCT: Geom_Axis1Placement::SetDirection via OCCTAxis1PlacementSetDirection.

setLocation(_:)

Sets the axis origin point.

public func setLocation(_ loc: SIMD3<Double>)
  • OCCT: Geom_Axis1Placement::SetLocation via OCCTAxis1PlacementSetLocation.