Turfano

A faithful .NET port of TurfJS — the geospatial analysis library — with its own GeoJSON types, its own typed quantities, and zero external dependencies in the core package.

Packages

• Turfano (core): the Geo facade (namespace Turfano.GeoJson), a faithful port of the @turf/* function index — Distance, Bearing, Area, Union, Buffer (via satellite), Voronoi, Isolines, and dozens more — over its own GeoJSON record types (Point, Polygon, Position, ...) and its own typed quantities (Turfano.Units.Length/Area/Angle). No NetTopologySuite, no UnitsNet — AOT and trimming friendly.
• Turfano.NetTopologySuite (satellite): bridges Turfano's GeoJSON types to NetTopologySuite's via NtsConvert.ToNts/FromNts (a zero-Coordinate, packed-sequence boundary), plus a Buffer extension implemented on top of NTS (the one operation that genuinely needs a full planar geometry engine).

Why a from-scratch port instead of building on NetTopologySuite?

NTS is a superb topology engine, but TurfJS's function surface and ergonomics (bearing, destination, along, midpoint, area, union, voronoi, isolines/isobands, ...) don't map cleanly onto it, and porting on top of NTS meant carrying NTS + UnitsNet as mandatory dependencies just to get TurfJS-shaped APIs. Turfano now ports each @turf function faithfully — same algorithm, same edge cases, same expected outputs, checked against the real TurfJS sources in reference/ — directly over plain GeoJSON types you can serialize as-is.

Quick start

using Turfano.GeoJson;

var origin = new Position(-122.4194, 37.7749);
var destination = new Position(-122.4094, 37.7849);

var distance = Geo.Distance(origin, destination); // Turfano.Units.Length
Console.WriteLine($"{distance.Kilometers:F3} km");

var square = Geo.Polygon(
    [new Position(0, 0), new Position(1, 0), new Position(1, 1), new Position(0, 1), new Position(0, 0)]
);
var area = Geo.Area(square); // Turfano.Units.Area
Console.WriteLine($"{area.SquareMeters:F1} m²");

var overlappingSquare = Geo.Polygon(
    [new Position(0.5, 0.5), new Position(1.5, 0.5), new Position(1.5, 1.5), new Position(0.5, 1.5), new Position(0.5, 0.5)]
);
var union = Geo.Union(square, overlappingSquare); // Turfano.GeoJson.Geometry?

Interop with NetTopologySuite

Need actual NTS geometries — to interoperate with an NTS-based stack, or to run Buffer — add the Turfano.NetTopologySuite package:

using Turfano.NetTopologySuite;

var buffered = square.Buffer(Turfano.Units.Length.FromKilometers(10)); // @turf/buffer

var ntsGeometry = NtsConvert.ToNts(square);
var backToTurfano = NtsConvert.FromNts(ntsGeometry);

Status

Pre-1.0 (1.0.0-rc.1). The Geo facade covers the full @turf function index; the API may still evolve before 1.0.0. Targets net8.0, net9.0 and net10.0.

Third-party attributions

Turfano ports algorithms from TurfJS, polyclip-ts, splaytree-ts, earcut and d3-voronoi. See NOTICE for the full attributions and licenses.

Development

See CLAUDE.md for build/test commands and repository conventions.