BREP Kernel Reference

This page describes the structure of the BREP kernel and where responsibilities live in src/BREP. It is the architecture overview, not the canonical method reference.

Use these pages alongside it:

Class Docs

Core types

  • Solid / Face / Edge / Vertex – Core geometry and selection primitives. API docs live under docs/api/.
  • AssemblyComponent – Assembly-level grouping and transform unit for constraints.

Primitives (src/BREP/primitives.js)

All extend Solid and immediately generate geometry.

  • Cube({ x=1, y=1, z=1, name })
  • Pyramid({ bL=1, s=4, h=1, name }) (s is side count ≥ 3)
  • Sphere({ r=1, resolution=24, name })
  • Cylinder({ radius=1, height=1, resolution=32, name })
  • Cone({ r1=0.5, r2=1, h=1, resolution=32, name })
  • Torus({ mR=2, tR=0.5, resolution=48, arcDegrees=360, name })

Feature solids

- ExtrudeSolid – { face, distance=1 | dir:Vector3, distanceBack=0, name='Extrude' }.

  • Sweep – { face, sweepPathEdges=[], distance=1, distanceBack=0, mode='translate', name='Sweep', omitBaseCap=false }.
  • Revolve – { face, axis, angle=360, resolution=64, name='Revolve' }.
  • TubeSolid (Tube) – { points=[], radius=1, innerRadius=0, resolution=32, closed=false, name='Tube' }.

- ChamferSolid – { edgeToChamfer, distance=1, sampleCount=50, snapSeamToEdge=true, sideStripSubdiv=8, seamInsetScale=1e-3, direction='INSET'|'OUTSET', inflate=0, flipSide=false, debug=false, debugStride=12 }.

  • OffsetShellSolid.generate(sourceSolid, distance, { newSolidName, featureId='OffsetShell' }) – Static helper to build offset shells.
  • Face.thicken(distance, options) – Face-level helper for turning a rendered face into a closed solid.

Face thickening (src/BREP/faceThicken.js)

  • thickenFaceToSolid(face, distance, options = {}) is the implementation behind Face.thicken(...).
  • Requires a valid face with triangulated geometry and a non-zero finite distance.
  • Tries a stitched-shell build first, then falls back to deterministic prism-union construction when needed.
  • Emits diagnostics on the result:

    • - result.__thickenMethod - result.__thickenClassificationMethod - result.__thickenDiagnostics - result.userData.thicken

  • Propagates available source-face metadata onto the generated start/end cap faces.

Fillet utilities (src/BREP/fillets/fillet.js)

- filletSolid({ edgeToFillet, radius, sideMode='INSET'|'OUTSET', inflate=0.1, resolution=32, showTangentOverlays=false, debug=false, name='fillet' }) – Builds wedge/tube helpers and returns { finalSolid, tube, wedge }; overlays add tangency polylines to the tube for debugging/PMI tagging.

  • computeFilletCenterline(edgeObj, radius, sideMode) – Returns centerline/tangents/edge polylines plus a closedLoop flag.
  • attachFilletCenterlineAuxEdge(solid, edgeObj, radius, sideMode='INSET', name='FILLET_CENTERLINE', options) – Adds centerline as an aux edge; options mirrors Solid.addAuxEdge.

Boolean helper

- applyBooleanOperation(partHistory, baseSolid, booleanParam, featureID) – Runs UNION|INTERSECT|SUBTRACT between baseSolid and booleanParam.targets (objects or names). Returns { added, removed }. Subtract semantics invert: each target subtracts the new base.

Conversion and repair

  • MeshToBrep – new MeshToBrep(geometryOrMesh, faceDeflectionAngle=30, weldTolerance=1e-5) groups triangles into faces based on normal deflection and welds shared vertices.
  • MeshRepairer – Per-geometry repair pipeline:

- weldVertices(geometry, epsilon=1e-4) - fixTJunctions(geometry, lineEps=5e-4, gridCell=0.01) - removeOverlappingTriangles(geometry, posEps=1e-6) - fillHoles(geometry) - fixTriangleNormals(geometry) - repairAll(geometry, { weldEps=5e-4, lineEps=5e-4, gridCell=0.01 })

How To Read The Kernel Docs

  • Start here when you need file-level orientation or want to know which module owns a behavior.
  • Use docs/api/ when you need exact method behavior or examples.
  • Use brep-api.md when you need to know what is exported from BREP.js.
  • Use brep-model.md when you want the compact data-model summary.

Example: boolean with primitives

javascript 
import { BREP } from '../src/BREP/BREP.js';

const box = new BREP.Cube({ x: 20, y: 10, z: 10, name: 'Box' });
const hole = new BREP.Cylinder({ radius: 3, height: 10, name: 'Hole' });
hole.position.set(10, 5, 0);
hole.bakeTransform(hole.matrixWorld);

const result = box.subtract(hole);
result.name = 'BoxWithHole';
result.visualize();