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:

• Kernel and Geometry Docs for the navigable kernel doc section.
• BREP Class API Reference for per-method docs.
• BREP.js Export Map and Usage for public exports.
• Solid Developer Guide for the high-level Solid workflow.

Class Docs

• Solid API Index
• Face API Index
• Edge API Index
• Solid Developer Guide

Core types

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

Primitives (src/BREP/primitives.ts)

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.ts)

• 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.ts)

• 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 the Developer API Reference 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

import { BREP } from '../src/BREP/BREP.ts';

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();