Glossary
Terms used throughout brepjs documentation, in alphabetical order. Where a term has a chapter dedicated to it, the chapter is linked.
A
autoHeal — operation that runs OpenCascade's ShapeFix_Shape to repair gaps, sew faces, fix orientations, and propagate tolerances. Always call on imported shapes before further operations. See Healing & Sewing.
Adapter (kernel adapter) — a class implementing KernelInterface that bridges brepjs to a specific geometry kernel. Two ship: OCCT and brepkit. See Writing a Custom Kernel.
B
B-Rep (Boundary Representation) — a 3D shape representation as a set of mathematical surfaces (faces) bounded by curves (edges) connected at points (vertices). Contrast with mesh (triangles). See B-Rep vs Mesh.
box — primitive function returning a ValidSolid rectangular volume. box(width, depth, height).
Boolean operation — fuse (union), cut (subtraction), intersect (intersection). The primary composition tool. See Boolean Operations.
Branded type — a TypeScript phantom property attached to a base type to enforce nominal typing. Edge, Wire, Face are all the same JavaScript object shape but cannot be substituted for each other. See Types That Prove Geometry Is Valid.
BRepCheck — OpenCascade's validity checker. A solid passing BRepCheck is a ValidSolid. See Tolerance and Validity.
BrepError — the error type carried by Result.error. Has code (stable string), message (human-readable), suggestion (optional recovery hint), cause (optional underlying error).
BrepWrapperError — thrown by the fluent shape() wrapper when an underlying operation fails. Carries the same fields as BrepError.
brepkit — Rust-based geometry kernel, in active development as a faster alternative to OpenCascade. Used via brepkit-wasm package and BrepkitAdapter. See Kernels.
C
Chamfer — beveled edge replacement. chamfer(shape, edges, distance). See Fillets & Chamfers.
ClosedWire — validity-branded wire that has been proven to form a closed loop. Required by face(). See Types.
Compound — a collection of shapes that aren't necessarily connected. The catch-all type for operations that may return multiple disconnected pieces.
CompSolid — a compound containing only solids.
Conformance suite — the test suite that runs against every supported kernel to verify behaviour parity. See Kernel Conformance Suite.
Curvature — a number describing how sharply a curve or surface bends. For a circle of radius r, curvature is 1/r. Returned by curveCurvatureAt and faceCurvatureAt.
D
Drawing (Drawing<'2D'>) — a 2D shape used in the Drawing API. Built with drawCircle, drawRectangle, etc. Operates on with drawingFuse, drawingCut, drawingFillet. Projected to a Sketch via drawingToSketchOnPlane.
DisposalScope — manual scope for tracking and disposing handles. scope.track(shape) registers; scope.dispose() releases in LIFO order. See Memory Management.
E
Edge — a curve segment between two vertices. Curve types: LINE, CIRCLE, ELLIPSE, BEZIER, BSPLINE, OFFSET. See The Topology Hierarchy.
edgeFinder — query builder for selecting edges. Filters chain (inDirection, withLength, ofCurveType, etc.). See Finders & Queries.
extrude — operation that pushes a face along its normal to make a solid. extrude(face, height). See Lofts, Sweeps, Revolves.
F
Face — a bounded region of a mathematical surface. The most common surface types: PLANE, CYLINDER, CONE, SPHERE, TORUS, BSPLINE_SURFACE. See Topology.
faceFinder — query builder for selecting faces. Filters chain (inDirection, withArea, ofSurfaceType, etc.).
Fillet — circular-arc edge rounding. fillet(shape, edges, radius). See Fillets & Chamfers.
Fluent wrapper — the shape() API that returns chainable wrappers (Wrapped3D, WrappedFace, etc.). Auto-unwraps Result and throws BrepWrapperError on failure.
Functional API — the canonical API: standalone functions in *Fns.ts files that take and return branded types. Returns Result<T,E> for fallible operations.
G
glTF / GLB — web-friendly mesh format. Exported via exportGltf. See Import & Export.
H
Handle — a brepjs shape value at runtime; a TypeScript object wrapping a kernel WASM resource. Wraps .wrapped (the kernel object).
Healing — repairing minor invalidities in shapes (gaps, mis-orientations, tolerance issues). The primary operation is autoHeal. See Healing & Sewing.
Helix — a 3D curve resembling a spring. Built with helix({ pitch, height, radius }). Use as a sweep path for threads.
I
init() — auto-detect kernel initializer. Resolves with the kernel ID picked.
initFromOC(oc) — manual initializer using a pre-loaded OpenCascade module.
Intersect — boolean returning the volume common to two shapes.
isOk / isErr — type guards on Result<T,E> that narrow result.value or result.error.
K
Kernel — the WASM-based geometry library underlying brepjs. Two ship: OpenCascade (production) and brepkit (development). See Kernels.
KernelInterface — the abstract interface every kernel adapter implements. Located at src/kernel/types.ts.
L
Layer (architecture) — brepjs is layered 0–3 with downward-only imports. See Architecture.
Loft — operation interpolating between two or more profiles. loft([profile1, profile2, ...]). See Lofts, Sweeps, Revolves.
M
ManifoldShell — validity-branded shell where every edge is shared by exactly two faces. The shell bounds a solid.
match — pattern-match operation on Result<T,E> that takes { ok, err } handlers and returns a value.
Manifold (in geometry) — a shape whose surface is locally flat at every point. Manifold shells are watertight.
Mesh — triangle representation. Produced from B-Rep via shape(s).mesh({ tolerance }). The integration point with Three.js. See Three.js Integration.
Minkowski sum — operation in OpenSCAD often used as a workaround for fillets. brepjs does not ship a generic Minkowski; use fillet, chamfer, shell for the common cases.
O
OCCT (OpenCascade Technology) — the C++ geometry kernel underlying brepjs-opencascade.
OrientedFace — validity-branded face with a determined normal direction. Required by extrude, revolve.
P
Pattern checker — npm run check:patterns. AST-based linter for architectural invariants. See Pattern Checker Rules.
Pattern operation (geometric) — linearPattern, circularPattern. Distribute copies of a shape on a grid or around an axis.
Phantom type / phantom property — a type-level marker with no runtime presence. brepjs uses phantoms for shape brand, dimension, and validity.
Plane — a 2D coordinate system in 3D space. Sketches are built on planes. Built-in names: 'XY', 'YZ', 'XZ'. Custom planes via Plane value (origin + normal).
R
Replicad — a peer code-CAD library wrapping OpenCascade. brepjs's closest comparison. See Coming from Replicad.
Result<T, E> — discriminated-union type for fallible operations. { ok: true, value } or { ok: false, error }. See Result and Errors.
Revolve — operation rotating a 2D profile around an axis. revolve(face) (default 360°), revolve(face, { angle, axis }).
S
Shell — a connected set of faces. Closed shells bound solids. Open shells are intermediate construction results.
Shell operation — shell(solid, openFaces, thickness). Hollows a solid, removing the listed faces and adding a wall.
shape() — the fluent wrapper. shape(b).cut(c).fillet(2).val.
Sketch — a planar face built from a closed wire. The output of Sketcher.close() and sketchCircle() etc.
Sketcher — the 2D builder class. new Sketcher('XY').movePointerTo([0,0]).lineTo([10,0]).close().extrude(5). See 2D Sketching.
Smart constructor — function that performs a runtime check and returns a validity-branded type if the check passes. Examples: closedWire(w), manifoldShell(s).
Solid — a 3D volume bounded by one or more closed shells. The output of most CAD operations.
STEP — ISO 10303 file format for B-Rep shapes. Round-trips with desktop CAD. Exported via exportSTEP, imported via importSTEP.
STL — triangle-mesh file format for 3D printing. Exported via exportSTL, imported via importSTL (lossy).
Sweep — operation dragging a profile along a path. sweep(profile, path). See Lofts, Sweeps, Revolves.
T
Tolerance — a small distance below which the kernel treats two points as the same. Default 1e-7 for OpenCascade. See Tolerance and Validity.
Topology (in B-Rep) — the connectivity structure of a shape: which edges meet at which vertices, which wires bound which faces, which faces compose which shells. See The Topology Hierarchy.
Type guard — function returning a typed boolean (isClosedWire(w): w is ClosedWire). Narrows the input type in conditionals.
U
unwrap — extracts result.value or throws on error. Use in scripts and tests; not in production code that needs recovery.
using (TypeScript keyword) — invokes Symbol.dispose when the variable goes out of scope. brepjs handles support using for automatic cleanup.
V
ValidSolid — validity-branded solid that has passed BRepCheck. Returned by primitive constructors (box, cylinder, sphere).
Validity brand — phantom property encoding a topological invariant (ClosedWire, OrientedFace, ManifoldShell, ValidSolid).
Vertex — a point in 3D space. The lowest level of the topology hierarchy.
vertexFinder — query builder for selecting vertices.
W
Wire — a connected chain of edges. Closed wires (every endpoint shared between two edges) form face boundaries.
wireFinder — query builder for selecting wires.
withScope — withScope((scope) => { scope.track(...); ... }). Constructs a DisposalScope, runs the callback, disposes everything tracked, even on exception.
withKernel — withKernel(id, fn). Runs fn synchronously with the named kernel active. Don't pass async callbacks. See Kernels.
Workbench — Replicad's name for its in-browser playground. brepjs has a similar playground.
Next steps
- Cheat Sheet — code reference for every concept above
- Function Lookup — alphabetical index of every brepjs export
- API Reference — searchable TypeDoc