Shapemetry API

---

Shapemetry API / Shape2d

Class: Shape2d

Defined in: curve2d/Shape2d.ts:305

A single 2D curve loop and the bridge between 2D and 3D. Implements the shared curve interface. Used as sketch plane, section plane, or NURBS UV space, then transformed into 3D.

Implements

• Curve2d

Constructors

Constructor

new Shape2d(segments?): Shape2d

Defined in: curve2d/Shape2d.ts:308

Parameters

segments?

ShapeSegment2d[] = []

Returns

Shape2d

Properties

segments

segments: ShapeSegment2d[]

Defined in: curve2d/Shape2d.ts:306

Accessors

start

Get Signature

get start(): Point2d

Defined in: curve2d/Shape2d.ts:310

Returns

Point2d

Implementation of

Curve2d.start

---

end

Get Signature

get end(): Point2d

Defined in: curve2d/Shape2d.ts:311

Returns

Point2d

Implementation of

Curve2d.end

---

isClosed

Get Signature

get isClosed(): boolean

Defined in: curve2d/Shape2d.ts:312

Returns

boolean

Implementation of

Curve2d.isClosed

Methods

toJSON()

toJSON(): Shape2dJSON

Defined in: curve2d/Shape2d.ts:317

Returns

Shape2dJSON

Implementation of

Curve2d.toJSON

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fromPoints()

static fromPoints(points, isClosed?): Shape2d

Defined in: curve2d/Shape2d.ts:320

Build a shape from a polyline (sequence of points), as chained LineSegment2d.

Parameters

points

Point2d[]

isClosed?

boolean = false

Returns

Shape2d

---

line()

static line(start, end): Shape2d

Defined in: curve2d/Shape2d.ts:330

Single LineSegment2d shape.

Parameters

start

Point2d

end

Point2d

Returns

Shape2d

---

fromNurbsCurve()

static fromNurbsCurve(curve): Shape2d

Defined in: curve2d/Shape2d.ts:347

Wrap a (planar, z≈0) NURBS curve as a Shape2d losslessly by decomposing it into its constituent Bezier spans — one segment per span — preserving the exact curvature (no polyline/chord approximation).

Each Bezier span maps to a native ShapeSegment2d: degree 1 → LineSegment2d, degree 2 → QuadraticBezier2d, degree 3 → CubicBezier2d. Degree-0/1 curves (and degree < 2 spans) are emitted as line segments. Splines of degree > 3 (rare; NurbsCurve.spline clamps to point count) cannot be represented as an exact cubic, so such a span is emitted as a cubic that matches the span endpoints and end tangents — far tighter than the old fixed 0.1 chord polyline.

Parameters

curve

NurbsCurve

Returns

Shape2d

---

catmullRom()

static catmullRom(points): Shape2d

Defined in: curve2d/Shape2d.ts:398

Catmull-Rom spline through points → chain of cubic Béziers (one per span). Tangent at each interior point: (P[i+1] - P[i-1]) / 6. Endpoints: clamped. Returns line if 2 points, empty Shape2d if fewer.

Parameters

points

Point2d[]

Returns

Shape2d

---

lastEnd()

lastEnd(): Point2d | undefined

Defined in: curve2d/Shape2d.ts:418

Returns

Point2d | undefined

---

addCurve()

addCurve(seg): Shape2d

Defined in: curve2d/Shape2d.ts:420

Parameters

seg

ShapeSegment2d

Returns

Shape2d

---

close()

close(): Shape2d

Defined in: curve2d/Shape2d.ts:424

Returns

Shape2d

---

length()

length(): number

Defined in: curve2d/Shape2d.ts:431

Returns

number

Implementation of

Curve2d.length

---

boundingBox()

boundingBox(): BoundingBox2d

Defined in: curve2d/Shape2d.ts:437

Returns

BoundingBox2d

Implementation of

Curve2d.boundingBox

---

reverse()

reverse(): Shape2d

Defined in: curve2d/Shape2d.ts:444

Returns

Shape2d

Implementation of

Curve2d.reverse

---

toPolyline()

toPolyline(chordTolerance): Point2d[]

Defined in: curve2d/Shape2d.ts:451

Sample shape to a polyline (sequence of points). Closed shapes do NOT repeat the first point at the end.

Parameters

chordTolerance

number

Returns

Point2d[]

---

signedArea()

signedArea(): number

Defined in: curve2d/Shape2d.ts:459

Returns

number

---

transform()

transform(m): Shape2d

Defined in: curve2d/Shape2d.ts:472

Parameters

m

Transformation2d

Returns

Shape2d

Implementation of

Curve2d.transform

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clone()

clone(): Shape2d

Defined in: curve2d/Shape2d.ts:476

Returns

Shape2d

Implementation of

Curve2d.clone

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toNurbsCurve()

toNurbsCurve(): NurbsCurve

Defined in: curve2d/Shape2d.ts:478

Returns

NurbsCurve

---

pointAt()

pointAt(t): Point2d

Defined in: curve2d/Shape2d.ts:480

Parameters

t

number

Returns

Point2d

Implementation of

Curve2d.pointAt

---

tangentAt()

tangentAt(t): Vector2d

Defined in: curve2d/Shape2d.ts:485

Parameters

t

number

Returns

Vector2d

Implementation of

Curve2d.tangentAt

---

axesAtParam()

axesAtParam(t): Axes2d

Defined in: curve2d/Shape2d.ts:491

Parameters

t

number

Returns

Axes2d

Implementation of

Curve2d.axesAtParam

---

lengthAt()

lengthAt(t): number

Defined in: curve2d/Shape2d.ts:496

Parameters

t

number

Returns

number

Implementation of

Curve2d.lengthAt

---

paramAtLength()

paramAtLength(s): number

Defined in: curve2d/Shape2d.ts:497

Parameters

s

number

Returns

number

Implementation of

Curve2d.paramAtLength

---

closestPoint()

closestPoint(p): Point2d

Defined in: curve2d/Shape2d.ts:499

Parameters

p

Point2d

Returns

Point2d

Implementation of

Curve2d.closestPoint

---

splitAt()

splitAt(t): [Shape2d, Shape2d]

Defined in: curve2d/Shape2d.ts:504

Parameters

t

number

Returns

[Shape2d, Shape2d]

Implementation of

Curve2d.splitAt

---

fillet()

fillet(radius, vertexFilter?): Shape2d

Defined in: curve2d/Shape2d.ts:512

Parameters

radius

number

vertexFilter?

((p, i) => boolean) | null

Returns

Shape2d

---

chamfer()

chamfer(distance, vertexFilter?): Shape2d

Defined in: curve2d/Shape2d.ts:538

Parameters

distance

number

vertexFilter?

((p, i) => boolean) | null

Returns

Shape2d

---

_modifyCorners()

_modifyCorners(makeCut, vertexFilter): Shape2d

Defined in: curve2d/Shape2d.ts:559

Parameters

makeCut

(vertex, previous, next) => { pointBefore: Point2d; pointAfter: Point2d; seg: ShapeSegment2d; } | null

vertexFilter

((p, i) => boolean) | null

Returns

Shape2d

---

offset()

offset(distance, chordTolerance?, joinType?): Shape2d | null

Defined in: curve2d/Shape2d.ts:595

Lateral offset of an open shape by distance (positive = right of direction). Returns one offset shape (the picked side), or null if degenerate. Samples to a polyline first then runs Clipper inflate with butt caps.

Parameters

distance

number

chordTolerance?

number = 0.5

joinType?

JoinType = JoinType.Miter

Returns

Shape2d | null

---

thicken()

thicken(distance, chordTolerance?, joinType?, endType?): Shape2d[]

Defined in: curve2d/Shape2d.ts:656

Thicken open shape → closed polygons (one outer + optional holes).

Parameters

distance

number

chordTolerance?

number = 0.5

joinType?

JoinType = JoinType.Round

endType?

EndType = EndType.Round

Returns

Shape2d[]

---

fitCurve()

static fitCurve(points, tolerance, minArcPoints?, maxArcRadius?): Shape2d

Defined in: curve2d/Shape2d.ts:683

Fit a polyline of sampled points into a Shape2d of LineSegment2d / Ellipse2d / CubicBezier2d.

Two-pass arc-first segmentation:

1. Enumerate maximal arc candidates via incremental algebraic LSQ circle fit at each start index.
2. Greedy non-overlap selection (longest first, endpoint-sharing allowed).
3. Fill gaps: line if straight-within-tol, otherwise Schneider cubic-bezier fit (Graphics Gems 1990) with arc-derived G1 tangents at boundaries.

Parameters

points

Point2d[]

tolerance

number

squared deviation accepted both for circle membership and bezier max-error.

minArcPoints?

number = 4

minimum points required to form an arc (default 4).

maxArcRadius?

number = 1e6

circles wider than this are treated as lines (default 1e6).

Returns

Shape2d

---

offset()

static offset(shapes, distance, endType?): Shape2d[]

Defined in: curve2d/Shape2d.ts:716

Inflate closed/open shapes by distance. Closed → polygon offset; open → stroke with chosen end type.

Parameters

shapes

Shape2d[]

distance

number

endType?

OffsetEndType = 'round'

Returns

Shape2d[]

---

thicken()

static thicken(shapes, distance, joinType?, endType?, miterLimit?): Shape2d[]

Defined in: curve2d/Shape2d.ts:757

Stroke around shapes with distance (open paths capped, closed paths joined). Merges connected open paths first.

Parameters

shapes

Shape2d[]

distance

number

joinType?

OffsetJoinType = 'round'

endType?

OffsetEndType = 'round'

miterLimit?

number = 4

Returns

Shape2d[]