fem_tutos/node_modules/d3-shape/src/symbol/star.js

import {sin, cos, sqrt, pi, tau} from "../math.js";

const ka = 0.89081309152928522810;
const kr = sin(pi / 10) / sin(7 * pi / 10);
const kx = sin(tau / 10) * kr;
const ky = -cos(tau / 10) * kr;

export default {
  draw(context, size) {
    const r = sqrt(size * ka);
    const x = kx * r;
    const y = ky * r;
    context.moveTo(0, -r);
    context.lineTo(x, y);
    for (let i = 1; i < 5; ++i) {
      const a = tau * i / 5;
      const c = cos(a);
      const s = sin(a);
      context.lineTo(s * r, -c * r);
      context.lineTo(c * x - s * y, s * x + c * y);
    }
    context.closePath();
  }
};