d3plus-shape/es/src/geom/polygonInside.js

Fancy SVG shapes for visualizations

import { polygonContains } from "d3-polygon";
import segmentsIntersect from "./segmentsIntersect.js";

/**
    @function polygonInside
    @desc Checks if one polygon is inside another polygon.
    @param {Array} polyA An Array of `[x, y]` points to be used as the inner polygon, checking if it is inside polyA.
    @param {Array} polyB An Array of `[x, y]` points to be used as the containing polygon.
    @returns {Boolean}
*/
export default function (polyA, polyB) {
  var iA = -1;
  var nA = polyA.length;
  var nB = polyB.length;
  var bA = polyA[nA - 1];
  while (++iA < nA) {
    var aA = bA;
    bA = polyA[iA];
    var iB = -1;
    var bB = polyB[nB - 1];
    while (++iB < nB) {
      var aB = bB;
      bB = polyB[iB];
      if (segmentsIntersect(aA, bA, aB, bB)) return false;
    }
  }
  return polygonContains(polyB, polyA[0]);
}