GPC.js

A Port of the General Polygon Clipper library by the University of Manchester (http://www.cs.man.ac.uk/~toby/gpc/)

This module exports a single data type, Polygon, which can represent euclidean polygons of arbitrary complexity and perform binary set operations on them. Polygons are not directly constructable with new; new Polygon instances can be created with Polygon.fromPoints() or Polygon.fromVertices(), described below. Polygons are also immutable; all geometric operations return new Polygon instances as their results.

API

• readonly isEmpty: boolean Indicates whether the polygon has non-zero area.
• readonly isHole: boolean Indicates whether the polygon has negative area / is the boundary of a hole in a complex polygon.
• bounds: { minx: number, maxx: number, miny: number, maxy: number } Returns the minimal coordinate-aligned rectangular bounding box for the polygon.
• equals(obj: Polygon): boolean Determine whether two polygons have the same vertex set, including the categorization of vertices as belonging to positive boundaries or holes.
• toVertices(): { bounds: { x: number, y: number }[][], holes: { x: number, y: number }[][] } Exports a description of the polygon as a set of vanilla JS objects. bounds is a list of lists of vertices representing the boundaries of positive-area sub-polygons, while holes is a list of lists of vertices representing the boundaries of interior holes.
• static fromVertices({ bounds, holes }: { bounds: Vertex[][], holes: Vertex[][] }): Polygon Creates a complex polygon from an object of the same shape as returned by toVertices(). A Vertex can be an onject of the form { x: number, y: number } or a two-element array of [x, y].
• static fromPoints(points: Vertex[]): Polygon Creates a simple polygon from a list of vertices, where a Vertex can be an onject of the form { x: number, y: number } or a two-element array of [x, y].
• static intersection(...p: Polygon[]): Polygon Computes the geometric set intersection of a list of Polygons.
• intersection(...p: Polygon[]): Polygon Computes the geometric set intersection of this with a list of additional Polygons.
• static union(...p: Polygon[]): Polygon Computes the geometric set union of a list of Polygons.
• union(...p: Polygon[]): Polygon Computes the geometric set union of this with a list of additional Polygons.
• static xor(...p: Polygon[]): Polygon Computes the geometric symmetric set difference of a list of Polygons.
• xor(...p: Polygon[]): Polygon Computes the geometric symmetric set difference of this with a list of additional Polygons.
• static difference(first: Polygon, ...p: Polygon[]): Polygon Computes the geometric set difference of the first Polygon with a list of additional Polygons.
• difference(...p: Polygon[]): Polygon Computes the geometric set difference of this with a list of additional Polygons.