GeometryHelper

Geometry for engineering drawings and models, in two dimensions and in three, plus the label placement library that runs on the 2D half and bridges that carry shapes in and out of Tekla Structures, AutoCAD and IFC models. Every comparison is tolerance-aware, because coordinates that come out of a BIM model are never exact.

dotnet add package GeometryHelper

Where to start

Shared types	Tolerance, Angle, the enumerations, OffsetOptions, GeometryHelperLog
Geometry in the plane	points to polygons and faces; arcs, offsetting, combining regions
Geometry in space	points to solids; splitting, boolean bodies, meshes, local frames
Label placement	five algorithms behind one entry point
Packing boxes onto sheets	drawing views onto A0 to A4 sheets or sheets of a size of their own, a new sheet when one is full
AutoCAD	both ways with AutoCAD, arcs and bulges included
Tekla Structures	both ways with Tekla, and IFC reference models
IFC	IFC models into solids, through xBIM
API Reference	every type and member of all four, from the XML documentation

A first look

using GeometryHelper;
using GeometryHelper.Enums;
using GeometryHelper.Geometry;
using GeometryHelper.Core;

// A slot: two straight sides and a half circle at each end, held the way a drawing holds it.
var slot = new GeoPolygonArc2(
    new[] { new GeoPoint2(0, 0), new GeoPoint2(200, 0), new GeoPoint2(200, 50), new GeoPoint2(0, 50) },
    new[] { 0.0, 1.0, 0.0, 1.0 });

slot.Area;                          // exact, counting what each arc adds beyond its chord
slot.Contains(new GeoPoint2(215, 25));   // true — the round end reaches past the chord

// Offsetting keeps the arcs: a round end of 25 grows to 45, about the same centre.
GeoPolygonArc2 grown = slot.Offset(20.0)[0];

// The booleans cannot, and say so by handing back the straight type.
var opening = new GeoPolygon2(new GeoPoint2(80, 15), new GeoPoint2(120, 15),
                              new GeoPoint2(120, 35), new GeoPoint2(80, 35));

GeoFace2[] pierced = slot.Subtract(opening);

The packages

Package	What it is
GeometryHelper	the geometry itself, 2D and 3D, and the label placement algorithms
GeometryHelper.CadConvert	both ways with AutoCAD, arcs and bulges included
GeometryHelper.TeklaConvert.2020 · 2025 · 2026	both ways with Tekla Structures, one package per version
GeometryHelper.IfcConvert	IFC models into solids, through xBIM

The library targets netstandard2.0 and its only dependency is Clipper2 (Boost Software License).