indexed-operations

Geometry library for point-in-polygon checks, adapting techniques from tg.

This is an alpha-quality library, experimentally in use in some projects. Please do your own testing and benchmarking before you use this in production. Once stable, more features, documentation, and benchmarks will follow.

Usage

Create an index based on coordinate arrays, then you can use the index to do a fast point-in-polygon check:

import { createPolygonIndex, pointInPolygonIndex } from 'indexed-operations'

declare const polygon: GeoJSON.Polygon
const polygonIndex = createPolygonIndex(polygon.coordinates)

const result = pointInPolygonIndex([53.217031067343015, 6.570103006941866], polygonIndex)
switch (result) {
  case 1: console.log('point is inside polygon'); break
  case 0: console.log('point is on the border of the polygon'); break
  case -1: console.log('point is outside polygon'); break
}

You can do the same for a multi-polygon:

import { createMultiPolygonIndex, pointInMultiPolygonIndex } from 'indexed-operations'

declare const polygon: GeoJSON.MultiPolygon
const polygonIndex = createMultiPolygonIndex(polygon.coordinates)

const result = pointInMultiPolygonIndex([53.217031067343015, 6.570103006941866], polygonIndex)
switch (result) {
  case 1: console.log('point is inside one of the polygons'); break
  case 0: console.log('point is on the border of one of the polygons'); break
  case -1: console.log('point is outside all polygons'); break
}

License

ⓒ Renée Kooi · Dual-licensed under Apache-2.0 or MIT at your option.