GeometryHelper 11.0.1

GeometryHelper

Geometry for engineering drawings and models, in two dimensions and in three, with the label placement algorithms that run on the 2D half. Written in C# and targeting netstandard2.0, so it loads into the .NET Framework hosts that Tekla Structures and AutoCAD provide as well as into modern .NET.

Every comparison that floating point error can affect takes a Tolerance, because coordinates that come out of a BIM model are never exact.

Use the default tolerance. The overloads without a tolerance read Tolerance.Global, which starts as Tolerance.Default: a thousandth of a millimetre for points and for flatness, in a model in millimetres. That is as exact as the corners of a modelled part are: two parts a hundredth apart are apart, and a thin overlap holds what it holds. A finer tolerance cuts as slivers the few ten-thousandths a modeller's rounding leaves faces off flat and parts apart, many times slower; a coarser one, passed to the call that needs it, takes what touches within it for touching. Never new Tolerance(): made so, every threshold is 0. For parts drawn against each other, as a model's are, cut with a SolidBooleanOptions whose Contact takes faces a hundredth apart for touching, and take a part's net body with TrySubtractAll: within a thousandth alone, a part keeps a skin of itself where a cutter's face stood a few thousandths inside it.

Installation

dotnet add package GeometryHelper

Quick start

using GeometryHelper;            // Tolerance, Angle, OffsetOptions
using GeometryHelper.Enums;      // LineEnd, OffsetJoin, PointLocation
using GeometryHelper.Geometry;   // every Geo type, 2D and 3D
using GeometryHelper.Core;       // every operation

// In the plane: grow a slab, then cut an opening out of it.
var slab = new GeoPolygon2(new GeoPoint2(0, 0), new GeoPoint2(4000, 0),
                           new GeoPoint2(4000, 2000), new GeoPoint2(0, 2000));
var duct = new GeoPolygon2(new GeoPoint2(1000, 500), new GeoPoint2(1400, 500),
                           new GeoPoint2(1400, 900), new GeoPoint2(1000, 900));

GeoPolygon2 grown = slab.Offset(50.0)[0];                 // 4100 x 2100
GeoFace2 pierced = Boolean2.Subtract(grown, duct)[0];     // one face, one hole

// In space: a beam trimmed where it runs into a wall.
var beam = new GeoLine3(new GeoPoint3(0, 0, 0), new GeoPoint3(3000, 0, 0));
var wall = new GeoPlane3(new GeoPoint3(2500, 0, 0), GeoVector3.XAxis);
beam.TryTrimTo(wall, LineEnd.End, out GeoLine3 cut);      // (0,0,0) -> (2500,0,0)

What is inside

Every operation is reachable both ways: the static form names the larger shape first, and the instance form sits on whichever of the two reads better where you are calling from.

Because both dimensions are one assembly, a flat shape in space can be laid out in its own plane, worked on with the whole 2D half of the library, and put back:

GeoCoordinateSystem3 frame = plate.GetFrame();
GeoFace2 flat = plate.ProjectToFace2(frame);
GeoFace3 back = flat.Subtract(openings)[0].ToFace3(frame);

Guides

The whole of it, searchable, with every type and member: https://nguyenthanguth.github.io/GeometryHelper/.

Coverage

dotnet test tests/GeometryHelper.UnitTest --collect:"XPlat Code Coverage"

writes a Cobertura file under TestResults. Only this library is counted.

Build and Test

dotnet build src/GeometryHelper/GeometryHelper.csproj
dotnet test  tests/GeometryHelper.UnitTest/GeometryHelper.UnitTest.csproj

Warnings are errors in CI, and every public member is documented, so a missing XML comment or a stale cref fails the build rather than landing quietly. Every example printed in the guides is also a test.

Licence

MIT. The clipping engine of Clipper2, by Angus Johnson, which is compiled into this package and resolves regions in the plane, is under the Boost Software License 1.0; THIRD-PARTY-NOTICES.md in the package holds its notice.