node-red-contrib-tak-registration
Version:
A Node-RED node to register to TAK and to help wrap files as datapackages to send to TAK
47 lines (46 loc) • 1.78 kB
JavaScript
import { featureCollection } from "@turf/helpers";
import Graph from "./lib/Graph.js";
import EdgeRing from "./lib/EdgeRing.js";
/**
* Polygonizes {@link LineString|(Multi)LineString(s)} into {@link Polygons}.
*
* Implementation of GEOSPolygonize function (`geos::operation::polygonize::Polygonizer`).
*
* Polygonizes a set of lines that represents edges in a planar graph. Edges must be correctly
* noded, i.e., they must only meet at their endpoints.
*
* The implementation correctly handles:
*
* - Dangles: edges which have one or both ends which are not incident on another edge endpoint.
* - Cut Edges (bridges): edges that are connected at both ends but which do not form part of a polygon.
*
* @name polygonize
* @param {FeatureCollection|Geometry|Feature<LineString|MultiLineString>} geoJson Lines in order to polygonize
* @returns {FeatureCollection<Polygon>} Polygons created
* @throws {Error} if geoJson is invalid.
*/
export default function polygonize(geoJson) {
var graph = Graph.fromGeoJson(geoJson);
// 1. Remove dangle node
graph.deleteDangles();
// 2. Remove cut-edges (bridge edges)
graph.deleteCutEdges();
// 3. Get all holes and shells
var holes = [], shells = [];
graph
.getEdgeRings()
.filter(function (edgeRing) { return edgeRing.isValid(); })
.forEach(function (edgeRing) {
if (edgeRing.isHole())
holes.push(edgeRing);
else
shells.push(edgeRing);
});
// 4. Assign Holes to Shells
holes.forEach(function (hole) {
if (EdgeRing.findEdgeRingContaining(hole, shells))
shells.push(hole);
});
// 5. EdgeRings to Polygons
return featureCollection(shells.map(function (shell) { return shell.toPolygon(); }));
}