Shapetypes

A 2d geometry library written in Typescript.

Features

• Essential geometry types – point, line, vector, polyline, and polygon.
• Basic transformations – rotate, translate, and change basis.
• Geometric relationships – intersections, booleans, and containment.
• An API that loosely follows Open NURBS and Rhino Common.
• Lots of documentation.

Installation

You can install shapetypes with npm:

npm install shapetypes

A quick example

import { Point, Polyline, Polygon, Rectangle, Vector } from 'shapetypes';

// Create a triangle
const triangle = new Polyline([new Point(0, 0), new Point(1, 1), new Point(2, 0)], true);
console.log(triangle.area);
// => 1

// Test to see if a point is inside
const testPoint = new Point(1, 0.5);
console.log(triangle.contains(testPoint));
// => True

// Move the triangle and see if the point is inside
const shifted = triangle.translate(new Vector(3, 4));
console.log(shifted.contains(testPoint));
// => False

// Create a rectangular polygon
const rectangle = new Rectangle(Plane.worldXY(), 10, 20);
const polygon = new Polygon(rectangle.toPolyline());
console.log(polygon.area);
// => 200

// Cut the triangle from the polygon
const result = polygon.difference(triangle);
console.log(result[0].area);
// => 199

Try on Runkit (note: Runkit is in Javascript rather than Typescript).

If you're coming from Rhino

If you've used Rhino, the Shapetypes syntax should feel familiar. There are a couple of important differences though:

1. There are no 3d functions – this library is just for 2d geometry.
2. All geometric objects are immutable, meaning they can't be changed after they're created. Rather than modifying an object, you can create a copy with different parameters. This can often be done through helper methods that have 'with' as a prefix, such as Point.withX (see example below).

import {Point} from 'shapetypes';

// Create a new point at 3,4
const p = new Point(3,4);

// Access the x parameter
console.log(p.x);
// => 3

// Try to change the x parameter 
p.x = 5;
// => This will throw an error since objects can't be modified after they're created.

// Instead, create a copy with a different x value.
const newPoint = p.withX(5);
console.log(newPoint.x);
// => 5

Alternatives

• Rhino3dm: A web assembly port of openNURBS. This is a much more extensive library that supports 3d geometry.
• VerbNurbs: A cross-platform Nurbs library that compiles to javascript.
• Javascript Topology Suite: A javascript library of geometric operations primarily for GIS data.
• Turf JS: Another javascript library of geometric operations primarily for GIS data.

Credits

Package based on Typescript Starter. Booleans via the Polygon-clipping library. This project is not affiliated with Rhino3d or McNeel in any way.

License

MIT License