SimplifyOptions

Input parameters for Mesh.simplified(_:). Declared as a nested type, Mesh.SimplifyOptions, and Sendable. Exactly one of targetTriangleCount or targetReduction must be set — passing both or neither makes simplified(_:) return nil.

Topics

• init(targetTriangleCount:targetReduction:preserveBoundary:preserveTopology:maxHausdorffDistance:)
• targetTriangleCount · targetReduction · preserveBoundary · preserveTopology · maxHausdorffDistance

init(targetTriangleCount:targetReduction:preserveBoundary:preserveTopology:maxHausdorffDistance:)

Creates a SimplifyOptions. Set exactly one of targetTriangleCount / targetReduction; the remaining parameters default to boundary- and topology-preserving with no Hausdorff cap.

public init(
    targetTriangleCount: Int? = nil,
    targetReduction: Double? = nil,
    preserveBoundary: Bool = true,
    preserveTopology: Bool = true,
    maxHausdorffDistance: Double? = nil
)

• Parameters:
  • targetTriangleCount — exact target triangle count; mutually exclusive with targetReduction.
  • targetReduction — fraction of triangles to remove in [0, 1]; mutually exclusive with targetTriangleCount.
  • preserveBoundary — keep free (boundary) edges from collapsing. Default true.
  • preserveTopology — reject collapses that change genus. Default true.
  • maxHausdorffDistance — optional deviation cap (absolute, input units, >= 0).
• Example:

  var options = Mesh.SimplifyOptions(targetReduction: 0.5)
  options.preserveBoundary = true
  options.maxHausdorffDistance = 0.05
  let result = mesh.simplified(options)
  

targetTriangleCount

Exact target number of triangles in the output mesh. Mutually exclusive with targetReduction. Must be in [1, input.triangleCount].

public var targetTriangleCount: Int?

• Example:

  let opts = Mesh.SimplifyOptions(targetTriangleCount: 5_000)
  

targetReduction

Fraction of input triangles to remove, in [0.0, 1.0]. 0.0 = no reduction; 1.0 = decimate as far as possible. Mutually exclusive with targetTriangleCount. The resolved target count is round(inputCount × (1 − targetReduction)), floored at 1.

public var targetReduction: Double?

• Example:

  let opts = Mesh.SimplifyOptions(targetReduction: 0.75)   // remove 75%
  

preserveBoundary

When true, edges on the mesh boundary (free edges) are not collapsed — important when decimating an open shell or a mesh that will be sewn back into a B-Rep.

public var preserveBoundary: Bool

• Example:

  var opts = Mesh.SimplifyOptions(targetReduction: 0.5)
  opts.preserveBoundary = true
  

preserveTopology

Forward-compatibility flag. The current backend always preserves topology — collapses that would change the surface’s genus (creating holes, splitting or merging components) are rejected regardless of this setting. Setting it to false does not (yet) produce more aggressive decimation.

public var preserveTopology: Bool

• Example:

  var opts = Mesh.SimplifyOptions(targetTriangleCount: 1_000)
  opts.preserveTopology = true   // always honoured today
  

maxHausdorffDistance

Optional Hausdorff distance cap. When set, decimation halts as soon as the measured deviation from the input mesh would exceed this value, even if the target count has not been reached. Units match the input mesh’s vertex coordinates (absolute). Must be >= 0; a negative value makes simplified(_:) return nil.

public var maxHausdorffDistance: Double?

• Example:

  var opts = Mesh.SimplifyOptions(targetReduction: 0.9)
  opts.maxHausdorffDistance = 0.05   // never deviate more than 0.05 units