@thi.ng/geom-tessellate/inset.js

2D/3D convex polygon tessellators

import { centroid } from "@thi.ng/geom-poly-utils/centroid";
import { mixN } from "@thi.ng/vectors/mixn";
const inset = (inset2 = 0.5, keepInterior = false) => (tess, faces, pids) => {
  const points = tess.pointsForIDs(pids);
  const c = centroid(points);
  const insets = tess.addPoints(points.map((p) => mixN([], p, c, inset2)));
  const n = pids.length - 1;
  for (let i = 0; i <= n; i++) {
    const j = i < n ? i + 1 : 0;
    faces.push([pids[i], pids[j], insets[j], insets[i]]);
  }
  if (keepInterior) faces.push(insets);
  return faces;
};
export {
  inset
};