Annotation & GD&T

OCCTSwift provides 3D annotation types for attaching measurement dimensions and positioned text to geometry (Annotation.swift), plus a typed GD&T authoring layer that creates STEP AP242-compatible dimensions, geometric tolerances, and datums on a Document (GDTWrite.swift).

Topics

• DimensionGeometry · LengthDimension · RadiusDimension · AngleDimension · DiameterDimension · TextLabel · PointCloud · Document Extensions — GD&T Enums & Structs · Document Extensions — Typed Read Path · Document Extensions — Write Path

DimensionGeometry

Geometry extracted from a dimension measurement, ready for Metal rendering or downstream layout.

public struct DimensionGeometry: Sendable {
    public let firstPoint: SIMD3<Double>
    public let secondPoint: SIMD3<Double>
    public let centerPoint: SIMD3<Double>
    public let textPosition: SIMD3<Double>
    public let circleNormal: SIMD3<Double>
    public let circleRadius: Double
    public let value: Double
    public let isValid: Bool
}

Returned by the geometry property on all four dimension types. Fields:

• firstPoint — first attachment point on the measured geometry.
• secondPoint — second attachment point on the measured geometry.
• centerPoint — angle vertex, or circle center for radius / diameter dimensions.
• textPosition — suggested 3D location for placing the dimension label.
• circleNormal — axis direction of the measured circle (radius / diameter only).
• circleRadius — radius of the measured circle (radius / diameter only; 0 for linear / angle dims).
• value — measured value: distance in model units for length/radius/diameter, radians for angle.
• isValid — whether the extraction succeeded; check before using the other fields.

DimensionGeometry.circleRadius

LengthDimension

Measures distance between two points, along a linear edge, or between two parallel faces.

LengthDimension.init?(from:to:)

Creates a length dimension between two 3D points.

public init?(from p1: SIMD3<Double>, to p2: SIMD3<Double>)

• Parameters: p1, p2 — endpoints of the measured span.
• Returns: nil if PrsDim_LengthDimension construction fails (e.g. coincident points).
• OCCT: PrsDim_LengthDimension(gp_Pnt, gp_Pnt, gp_Pln) — plane is chosen automatically perpendicular to the connecting vector.
• Example:

  if let dim = LengthDimension(from: SIMD3(0, 0, 0), to: SIMD3(10, 0, 0)) {
      print(dim.value)  // 10.0
  }
  

LengthDimension.init?(edge:)

Creates a length dimension measuring a single linear edge.

public init?(edge: Shape)

• Parameters: edge — a Shape wrapping a TopoDS_Edge that is straight (line segment).
• Returns: nil if edge is not a valid linear edge or dimension construction fails.
• OCCT: PrsDim_LengthDimension(TopoDS_Edge, gp_Pln).
• Example:

  let box = Shape.box(width: 10, height: 5, depth: 2)!
  for e in box.edges() {
      if let dim = LengthDimension(edge: e), dim.isValid {
          print(dim.value)
          break
      }
  }
  

LengthDimension.init?(face1:face2:)

Creates a length dimension between two parallel planar faces.

public init?(face1: Shape, face2: Shape)

• Parameters: face1, face2 — Shape values each wrapping a TopoDS_Face; the faces must be parallel planes.
• Returns: nil if the faces are not parallel or dimension construction fails.
• OCCT: PrsDim_LengthDimension(TopoDS_Face, TopoDS_Face).
• Example:

  let box = Shape.box(width: 10, height: 5, depth: 2)!
  let faces = box.faces()
  if let dim = LengthDimension(face1: faces[0].shape, face2: faces[1].shape) {
      print(dim.value)
  }
  

value

The measured distance.

public var value: Double { get }

• Returns: Distance in model units between the attached geometry points.
• OCCT: PrsDim_Dimension::GetValue().
• Example:

  let dim = LengthDimension(from: .zero, to: SIMD3(3, 4, 0))!
  print(dim.value)  // 5.0
  

isValid

Whether the dimension geometry is valid and the measured value is meaningful.

public var isValid: Bool { get }

• Returns: true if the underlying PrsDim_Dimension considers its geometry valid.
• OCCT: PrsDim_Dimension::IsValid().

setCustomValue(_:)

Overrides the measured value with a display value for annotation purposes.

public func setCustomValue(_ value: Double)

• Parameters: value — custom display value in model units.
• OCCT: PrsDim_Dimension::SetCustomValue(Standard_Real).
• Note: Affects rendered label text only; value continues to return the originally measured distance.

geometry

Geometry data for Metal rendering — attachment points, text position, and the measured value.

public var geometry: DimensionGeometry? { get }

• Returns: DimensionGeometry populated from the dimension’s internal geometry, or nil if extraction fails.
• OCCT: PrsDim_LengthDimension::FirstPoint(), SecondPoint(), GetValue().
• Example:

  if let dim = LengthDimension(from: SIMD3(0, 0, 0), to: SIMD3(5, 0, 0)),
     let geo = dim.geometry {
      print(geo.firstPoint, geo.secondPoint, geo.textPosition)
  }
  

RadiusDimension

Measures the radius of circular geometry such as a circle edge, arc, or cylindrical face.

RadiusDimension.init?(shape:)

Creates a radius dimension from a shape with circular geometry.

public init?(shape: Shape)

• Parameters: shape — a Shape wrapping circular geometry (edge or face).
• Returns: nil if the shape does not contain circular geometry or construction fails.
• OCCT: PrsDim_RadiusDimension(TopoDS_Shape).
• Example:

  let cyl = Shape.cylinder(radius: 5, height: 10)!
  if let dim = RadiusDimension(shape: cyl) {
      print(dim.value)  // ≈ 5.0
  }
  

value

The measured radius.

public var value: Double { get }

• OCCT: PrsDim_Dimension::GetValue().

isValid

Whether the dimension is valid.

public var isValid: Bool { get }

• OCCT: PrsDim_Dimension::IsValid().

setCustomValue(_:)

Overrides the displayed radius with a custom value.

public func setCustomValue(_ value: Double)

• OCCT: PrsDim_Dimension::SetCustomValue(Standard_Real).

geometry

Geometry data for Metal rendering.

public var geometry: DimensionGeometry? { get }

• Returns: DimensionGeometry with centerPoint set to the circle center and circleNormal set to the axis direction; nil on failure.
• OCCT: PrsDim_RadiusDimension::Circle(), GetValue().

AngleDimension

Measures angles between edges, faces, or a vertex-defined triple of points.

AngleDimension.init?(edge1:edge2:)

Creates an angle dimension between two edges.

public init?(edge1: Shape, edge2: Shape)

• Parameters: edge1, edge2 — Shape values wrapping linear or planar edges.
• Returns: nil if the edges are parallel or dimension construction fails.
• OCCT: PrsDim_AngleDimension(TopoDS_Edge, TopoDS_Edge).
• Example:

  let box = Shape.box(width: 10, height: 10, depth: 5)!
  let edges = box.edges()
  if edges.count >= 2,
     let dim = AngleDimension(edge1: edges[0].shape, edge2: edges[1].shape) {
      print(dim.degrees)
  }
  

AngleDimension.init?(first:vertex:second:)

Creates an angle dimension from three points: first, vertex, second.

public init?(first: SIMD3<Double>, vertex: SIMD3<Double>, second: SIMD3<Double>)

• Parameters: first — first arm point; vertex — the angle’s apex; second — second arm point.
• Returns: nil if the points are collinear or construction fails.
• OCCT: PrsDim_AngleDimension(gp_Pnt p1, gp_Pnt center, gp_Pnt p2).
• Example:

  let dim = AngleDimension(
      first:  SIMD3(1, 0, 0),
      vertex: SIMD3(0, 0, 0),
      second: SIMD3(0, 1, 0))
  print(dim?.degrees)  // Optional(90.0)
  

AngleDimension.init?(face1:face2:)

Creates an angle dimension between two planar faces.

public init?(face1: Shape, face2: Shape)

• Parameters: face1, face2 — Shape values wrapping planar TopoDS_Face sub-shapes.
• Returns: nil if either face is non-planar or construction fails.
• OCCT: PrsDim_AngleDimension(TopoDS_Face, TopoDS_Face).

value

The measured angle in radians.

public var value: Double { get }

• OCCT: PrsDim_Dimension::GetValue().

degrees

The measured angle converted to degrees.

public var degrees: Double { get }

Pure-Swift: value * 180.0 / .pi.

• Example:

  let dim = AngleDimension(first: SIMD3(1,0,0), vertex: .zero, second: SIMD3(0,1,0))!
  print(dim.degrees)  // 90.0
  

isValid

Whether the dimension is valid.

public var isValid: Bool { get }

• OCCT: PrsDim_Dimension::IsValid().

setCustomValue(_:)

Overrides the displayed angle (in radians).

public func setCustomValue(_ value: Double)

• Parameters: value — custom angle in radians.
• OCCT: PrsDim_Dimension::SetCustomValue(Standard_Real).

geometry

Geometry data for Metal rendering.

public var geometry: DimensionGeometry? { get }

• Returns: DimensionGeometry with centerPoint at the angle vertex and value in radians; nil on failure.
• OCCT: PrsDim_AngleDimension::FirstPoint(), SecondPoint(), CenterPoint(), GetValue().

DiameterDimension

Measures the diameter of circular geometry (edge, arc, or cylindrical face).

DiameterDimension.init?(shape:)

Creates a diameter dimension from a shape with circular geometry.

public init?(shape: Shape)

• Parameters: shape — a Shape wrapping circular geometry.
• Returns: nil if the shape does not contain circular geometry or construction fails.
• OCCT: PrsDim_DiameterDimension(TopoDS_Shape).
• Example:

  let cyl = Shape.cylinder(radius: 5, height: 10)!
  if let dim = DiameterDimension(shape: cyl) {
      print(dim.value)  // ≈ 10.0
  }
  

value

The measured diameter.

public var value: Double { get }

• OCCT: PrsDim_Dimension::GetValue().

isValid

Whether the dimension is valid.

public var isValid: Bool { get }

• OCCT: PrsDim_Dimension::IsValid().

setCustomValue(_:)

Overrides the displayed diameter with a custom value.

public func setCustomValue(_ value: Double)

• OCCT: PrsDim_Dimension::SetCustomValue(Standard_Real).

geometry

Geometry data for Metal rendering.

public var geometry: DimensionGeometry? { get }

• Returns: DimensionGeometry with centerPoint at the circle center, circleRadius set, and value equal to the diameter; nil on failure.
• OCCT: PrsDim_DiameterDimension::Circle(), GetValue().

TextLabel

A positioned 3D text annotation — a label with a location, string content, and optional character height.

TextLabel.init?(text:position:)

Creates a text label at a 3D position.

public init?(text: String, position: SIMD3<Double>)

• Parameters: text — label string; position — 3D anchor point in model space.
• Returns: nil if construction fails (e.g. empty string or bridge allocation error).
• OCCT: Internal OCCTTextLabel struct — stores string + gp_Pnt position.
• Example:

  if let label = TextLabel(text: "Datum A", position: SIMD3(0, 0, 10)) {
      label.setHeight(2.0)
      print(label.text)
  }
  

text

The label string. Readable and writable.

public var text: String { get set }

• OCCT (get): OCCTTextLabelGetInfo → copies the stored C string.
• OCCT (set): OCCTTextLabelSetText → replaces the stored string.
• Note: Returns "" if the info retrieval fails.

position

The 3D anchor point of the label. Readable and writable.

public var position: SIMD3<Double> { get set }

• OCCT (get): OCCTTextLabelGetInfo → reads the stored gp_Pnt.
• OCCT (set): OCCTTextLabelSetPosition(x:y:z:).
• Returns: .zero if info retrieval fails.

setHeight(_:)

Sets the character height for rendering the label text.

public func setHeight(_ height: Double)

• Parameters: height — character height in model units.
• OCCT: OCCTTextLabelSetHeight.
• Example:

  label.setHeight(3.5)
  

PointCloud

A colored point set for 3D visualization, backed by packed coordinate / color buffers.

PointCloud.init?(points:) (uncolored)

Creates a point cloud from an array of 3D positions without per-point colors.

public init?(points: [SIMD3<Double>])

• Parameters: points — array of 3D positions.
• Returns: nil if points is empty or allocation fails.
• OCCT: OCCTPointCloudCreate(const double*, int32_t) — packs XYZ into a flat Double buffer.
• Example:

  let pts: [SIMD3<Double>] = [SIMD3(0,0,0), SIMD3(1,0,0), SIMD3(0,1,0)]
  if let cloud = PointCloud(points: pts) {
      print(cloud.count)  // 3
  }
  

PointCloud.init?(points:colors:) (colored)

Creates a colored point cloud with per-point RGB values.

public init?(points: [SIMD3<Double>], colors: [SIMD3<Float>])

• Parameters: points — 3D positions; colors — per-point RGB values with components in [0, 1]. Must have the same count as points.
• Returns: nil if points.count != colors.count or allocation fails.
• OCCT: OCCTPointCloudCreateColored(const double*, const float*, int32_t).
• Example:

  let pts: [SIMD3<Double>] = [SIMD3(0,0,0), SIMD3(1,0,0)]
  let cols: [SIMD3<Float>] = [SIMD3(1,0,0), SIMD3(0,1,0)]
  if let cloud = PointCloud(points: pts, colors: cols) {
      print(cloud.colors.count)  // 2
  }
  

count

Number of points in the cloud.

public var count: Int { get }

• OCCT: OCCTPointCloudGetCount.

bounds

Axis-aligned bounding box of the point cloud.

public var bounds: (min: SIMD3<Double>, max: SIMD3<Double>)? { get }

• Returns: Tuple of min/max corners, or nil if the cloud is empty or bounds computation fails.
• OCCT: OCCTPointCloudGetBounds — iterates stored points to compute AABB.
• Example:

  if let cloud = PointCloud(points: [SIMD3(0,0,0), SIMD3(5,5,5)]),
     let bb = cloud.bounds {
      print(bb.min, bb.max)  // (0,0,0) (5,5,5)
  }
  

points

All point positions as an array.

public var points: [SIMD3<Double>] { get }

• Returns: Array of 3D positions in insertion order. Returns [] if the cloud is empty.
• OCCT: OCCTPointCloudGetPoints(cloud, buffer, count) — copies the packed buffer into the returned array.

colors

All per-point colors as an array.

public var colors: [SIMD3<Float>] { get }

• Returns: Array of RGB colors matching each point; [] if the cloud was created without colors.
• OCCT: OCCTPointCloudGetColors(cloud, buffer, count) — copies the packed Float buffer; returns empty if no color data is stored.

Document Extensions — GD&T Enums & Structs

These types are declared as extensions on Document in GDTWrite.swift and encode the STEP AP242 GD&T vocabulary.

Document.DimensionType

Maps OCCT’s XCAFDimTolObjects_DimensionType — the 32 dimension sub-types that STEP AP242 dimensions can carry.

public enum DimensionType: Int32, Sendable, CaseIterable {
    case locationNone = 0
    case locationCurvedDistance = 1
    case locationLinearDistance = 2
    case locationLinearDistanceFromCenterToOuter = 3
    case locationLinearDistanceFromCenterToInner = 4
    case locationLinearDistanceFromOuterToCenter = 5
    case locationLinearDistanceFromOuterToOuter = 6
    case locationLinearDistanceFromOuterToInner = 7
    case locationLinearDistanceFromInnerToCenter = 8
    case locationLinearDistanceFromInnerToOuter = 9
    case locationLinearDistanceFromInnerToInner = 10
    case locationAngular = 11
    case locationOriented = 12
    case locationWithPath = 13
    case sizeCurveLength = 14
    case sizeDiameter = 15
    case sizeSphericalDiameter = 16
    case sizeRadius = 17
    case sizeSphericalRadius = 18
    case sizeToroidalMinorDiameter = 19
    case sizeToroidalMajorDiameter = 20
    case sizeToroidalMinorRadius = 21
    case sizeToroidalMajorRadius = 22
    case sizeToroidalHighMajorDiameter = 23
    case sizeToroidalLowMajorDiameter = 24
    case sizeToroidalHighMajorRadius = 25
    case sizeToroidalLowMajorRadius = 26
    case sizeThickness = 27
    case sizeAngular = 28
    case sizeWithPath = 29
    case commonLabel = 30
    case dimensionPresentation = 31
}

Raw values match XCAFDimTolObjects_DimensionType integer codes directly. The enum has two families: location* cases (a dimension between two features, distinguished by which boundary of each feature the measurement runs between: center, inner, or outer) and size* cases (a single feature’s own extent). Neither OCCT’s header nor the STEP AP242 mapping documents each case beyond its name; the meanings below are a direct, literal reading of that name, not a separate source.

Each case is indexed below too, so a reference link can land on one directly; the table above is the authoritative description.

Document.DimensionType.dimensionPresentation

Document.GeomToleranceType

Maps OCCT’s XCAFDimTolObjects_GeomToleranceType — the 16 ASME / ISO geometric tolerance classes.

public enum GeomToleranceType: Int32, Sendable, CaseIterable {
    case none = 0
    case angularity = 1
    case circularRunout = 2
    case circularityOrRoundness = 3
    case coaxiality = 4
    case concentricity = 5
    case cylindricity = 6
    case flatness = 7
    case parallelism = 8
    case perpendicularity = 9
    case position = 10
    case profileOfLine = 11
    case profileOfSurface = 12
    case straightness = 13
    case symmetry = 14
    case totalRunout = 15
}

Raw values match XCAFDimTolObjects_GeomToleranceType integer codes. Names and meanings follow the ASME Y14.5 / ISO 1101 geometric dimensioning and tolerancing (GD&T) standard; OCCT’s enum is a direct transcription of that standard’s tolerance classes, grouped into form, orientation, location, and runout controls.

GeomToleranceType.totalRunout

Document.Dimension

Typed snapshot of a dimension read from or created on a Document.

public struct Dimension: Sendable, Hashable {
    public let type: DimensionType
    public let value: Double
    public let lowerTolerance: Double
    public let upperTolerance: Double
    public let index: Int
}

• type — the STEP AP242 dimension sub-type.
• value — nominal value (model units).
• lowerTolerance — lower tolerance bound (may be 0 if not set).
• upperTolerance — upper tolerance bound (may be 0 if not set).
• index — position in the document’s dimension sequence (for use with setDimensionTolerance(at:lower:upper:)).

Document.Dimension.lowerTolerance

Lower tolerance bound (may be 0 if not set).

Document.Dimension.upperTolerance

Upper tolerance bound (may be 0 if not set).

Document.GeomTolerance

Typed snapshot of a geometric tolerance entry.

public struct GeomTolerance: Sendable, Hashable {
    public let type: GeomToleranceType
    public let value: Double
    public let index: Int
}

• type — ASME / ISO tolerance class.
• value — tolerance zone value in model units.
• index — position in the document’s geom-tolerance sequence.

Document.Datum

Typed snapshot of a datum reference.

public struct Datum: Sendable, Hashable {
    public let name: String
    public let index: Int
}

• name — datum label string (e.g. "A", "B").
• index — position in the document’s datum sequence.

Document Extensions — Typed Read Path

These methods provide type-safe access to GD&T objects stored in a Document, complementing the raw Int32-returning read path in Document.swift.

typedDimension(at:)

Returns the typed dimension at a given index.

public func typedDimension(at index: Int) -> Dimension?

• Parameters: index — zero-based index within the document’s dimension label sequence.
• Returns: Dimension if the label exists and its XCAFDimTolObjects_DimensionType maps to a known DimensionType case; nil otherwise.
• OCCT: XCAFDoc_DimTolTool::GetDimensionLabels → XCAFDoc_Dimension::GetObject() → XCAFDimTolObjects_DimensionObject::GetType() / GetValues() / GetLowerTolValue() / GetUpperTolValue().
• Example:

  for i in 0..<doc.dimensionCount {
      if let dim = doc.typedDimension(at: i) {
          print(dim.type, dim.value)
      }
  }
  

typedGeomTolerance(at:)

Returns the typed geometric tolerance at a given index.

public func typedGeomTolerance(at index: Int) -> GeomTolerance?

• Parameters: index — zero-based index within the document’s geom-tolerance label sequence.
• Returns: GeomTolerance if the label exists and its type maps to a known GeomToleranceType case; nil otherwise.
• OCCT: XCAFDoc_DimTolTool::GetGeomToleranceLabels → XCAFDoc_GeomTolerance::GetObject() → XCAFDimTolObjects_GeomToleranceObject::GetType() / GetValue().
• Example:

  for i in 0..<doc.geomToleranceCount {
      if let tol = doc.typedGeomTolerance(at: i) {
          print(tol.type, tol.value)
      }
  }
  

typedDatum(at:)

Returns the typed datum at a given index.

public func typedDatum(at index: Int) -> Datum?

• Parameters: index — zero-based index within the document’s datum label sequence.
• Returns: Datum wrapping the datum name and index; nil if the label does not exist.
• OCCT: Delegates to Document.datum(at:) → XCAFDoc_DimTolTool::GetDatumLabels → XCAFDoc_Datum::GetObject() → XCAFDimTolObjects_DatumObject::GetName().

typedDimensions

All typed dimensions in the document.

public var typedDimensions: [Dimension] { get }

• Returns: Array of all Dimension values for which typedDimension(at:) succeeds.
• Example:

  let dims = doc.typedDimensions
  let diameters = dims.filter { $0.type == .sizeDiameter }
  

typedGeomTolerances

All typed geometric tolerances in the document.

public var typedGeomTolerances: [GeomTolerance] { get }

• Returns: Array of all GeomTolerance values for which typedGeomTolerance(at:) succeeds.

typedDatums

All typed datums in the document.

public var typedDatums: [Datum] { get }

• Returns: Array of all Datum values for which typedDatum(at:) succeeds.

Document Extensions — Write Path

Methods that author new GD&T objects on the document for round-trip through STEP AP242.

createDimension(on:type:value:lowerTolerance:upperTolerance:)

Creates a new STEP AP242 dimension on the document, attached to a shape label.

@discardableResult
public func createDimension(on shapeLabel: Int64,
                            type: DimensionType,
                            value: Double,
                            lowerTolerance: Double = 0,
                            upperTolerance: Double = 0) -> Int?

• Parameters:
  • shapeLabel: label ID of the shape to annotate (from Document.namingFindLabel(shape:)?.labelId, or from wherever the shape’s label ID was captured when it was imported or added).
  • type — the dimension sub-type (e.g. .sizeDiameter, .locationLinearDistance).
  • value — nominal measured value in model units.
  • lowerTolerance — lower tolerance; omit or pass 0 to leave unset.
  • upperTolerance — upper tolerance; omit or pass 0 to leave unset.
• Returns: Zero-based index of the new dimension in the document’s sequence, or nil on failure.
• OCCT: XCAFDoc_DimTolTool::AddDimension → XCAFDoc_DimTolTool::SetDimension → XCAFDimTolObjects_DimensionObject::SetType / SetValues + optionally SetLowerTolValue / SetUpperTolValue via setDimensionTolerance(at:lower:upper:).
• Example:

  if let shapeLabel = doc.labelForShape(shaft),
     let idx = doc.createDimension(on: shapeLabel,
                                   type: .sizeDiameter,
                                   value: 20.0,
                                   lowerTolerance: -0.1,
                                   upperTolerance: 0.0) {
      print("Created dimension at index \(idx)")
  }
  

createGeomTolerance(on:type:value:)

Creates a new geometric tolerance on the document, attached to a shape label.

@discardableResult
public func createGeomTolerance(on shapeLabel: Int64,
                                type: GeomToleranceType,
                                value: Double) -> Int?

• Parameters:
  • shapeLabel — label ID of the shape to annotate.
  • type — the ASME / ISO tolerance class (e.g. .flatness, .perpendicularity).
  • value — tolerance zone size in model units.
• Returns: Zero-based index of the new tolerance in the document’s geom-tolerance sequence, or nil on failure.
• OCCT: XCAFDoc_DimTolTool::AddGeomTolerance → XCAFDoc_DimTolTool::SetGeomTolerance → XCAFDimTolObjects_GeomToleranceObject::SetType / SetValue.
• Example:

  if let shapeLabel = doc.labelForShape(face),
     let idx = doc.createGeomTolerance(on: shapeLabel,
                                       type: .flatness,
                                       value: 0.05) {
      print("Flatness tolerance at index \(idx)")
  }
  

createDatum(name:)

Creates a new datum reference on the document.

@discardableResult
public func createDatum(name: String) -> Int?

• Parameters: name — datum identifier string (typically a single letter, e.g. "A").
• Returns: Zero-based index of the new datum in the document’s datum sequence, or nil on failure.
• OCCT: XCAFDoc_DimTolTool::AddDatum → XCAFDimTolObjects_DatumObject::SetName(TCollection_HAsciiString).
• Example:

  if let idxA = doc.createDatum(name: "A") {
      print("Datum A at index \(idxA)")
  }
  

setDimensionTolerance(at:lower:upper:)

Updates the tolerance bounds on an existing dimension.

@discardableResult
public func setDimensionTolerance(at index: Int,
                                  lower: Double,
                                  upper: Double) -> Bool

• Parameters:
  • index — zero-based dimension index (as returned by createDimension or used in typedDimension(at:)).
  • lower — lower tolerance value in model units.
  • upper — upper tolerance value in model units.
• Returns: true if the update succeeded; false if the index is out of range or the attribute is missing.
• OCCT: XCAFDoc_DimTolTool::GetDimensionLabels → XCAFDoc_Dimension::GetObject() → XCAFDimTolObjects_DimensionObject::SetLowerTolValue / SetUpperTolValue → XCAFDoc_Dimension::SetObject.
• Example:

  let idx = doc.createDimension(on: shapeLabel, type: .locationLinearDistance, value: 25.0)!
  let ok = doc.setDimensionTolerance(at: idx, lower: -0.05, upper: 0.05)
  #expect(ok)