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
87 lines (86 loc) • 3.92 kB
JavaScript
;
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
var convex_1 = __importDefault(require("@turf/convex"));
var centroid_1 = __importDefault(require("@turf/centroid"));
var helpers_1 = require("@turf/helpers");
var invariant_1 = require("@turf/invariant");
var meta_1 = require("@turf/meta");
/**
* Takes any {@link Feature} or a {@link FeatureCollection} and returns its [center of mass](https://en.wikipedia.org/wiki/Center_of_mass) using this formula: [Centroid of Polygon](https://en.wikipedia.org/wiki/Centroid#Centroid_of_polygon).
*
* @name centerOfMass
* @param {GeoJSON} geojson GeoJSON to be centered
* @param {Object} [options={}] Optional Parameters
* @param {Object} [options.properties={}] Translate Properties to Feature
* @returns {Feature<Point>} the center of mass
* @example
* var polygon = turf.polygon([[[-81, 41], [-88, 36], [-84, 31], [-80, 33], [-77, 39], [-81, 41]]]);
*
* var center = turf.centerOfMass(polygon);
*
* //addToMap
* var addToMap = [polygon, center]
*/
function centerOfMass(geojson, options) {
if (options === void 0) { options = {}; }
switch (invariant_1.getType(geojson)) {
case "Point":
return helpers_1.point(invariant_1.getCoord(geojson), options.properties);
case "Polygon":
var coords = [];
meta_1.coordEach(geojson, function (coord) {
coords.push(coord);
});
// First, we neutralize the feature (set it around coordinates [0,0]) to prevent rounding errors
// We take any point to translate all the points around 0
var centre = centroid_1.default(geojson, { properties: options.properties });
var translation = centre.geometry.coordinates;
var sx = 0;
var sy = 0;
var sArea = 0;
var i, pi, pj, xi, xj, yi, yj, a;
var neutralizedPoints = coords.map(function (point) {
return [point[0] - translation[0], point[1] - translation[1]];
});
for (i = 0; i < coords.length - 1; i++) {
// pi is the current point
pi = neutralizedPoints[i];
xi = pi[0];
yi = pi[1];
// pj is the next point (pi+1)
pj = neutralizedPoints[i + 1];
xj = pj[0];
yj = pj[1];
// a is the common factor to compute the signed area and the final coordinates
a = xi * yj - xj * yi;
// sArea is the sum used to compute the signed area
sArea += a;
// sx and sy are the sums used to compute the final coordinates
sx += (xi + xj) * a;
sy += (yi + yj) * a;
}
// Shape has no area: fallback on turf.centroid
if (sArea === 0) {
return centre;
}
else {
// Compute the signed area, and factorize 1/6A
var area = sArea * 0.5;
var areaFactor = 1 / (6 * area);
// Compute the final coordinates, adding back the values that have been neutralized
return helpers_1.point([translation[0] + areaFactor * sx, translation[1] + areaFactor * sy], options.properties);
}
default:
// Not a polygon: Compute the convex hull and work with that
var hull = convex_1.default(geojson);
if (hull)
return centerOfMass(hull, { properties: options.properties });
// Hull is empty: fallback on the centroid
else
return centroid_1.default(geojson, { properties: options.properties });
}
}
exports.default = centerOfMass;