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HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

              <main class="pa4 dark-gray mw7 center sans-serif min-vh-100 flex flex-column flex-row-ns items-center">
  <form class="measure-wide mr4-ns mb4 mb0-ns f5">
    <fieldset class="ba b--transparent pa0 mh0">
      <legend class="f5 b ph0 mh0 ttu tracked bb bw2 pv2 db w-100">
        Polygon Generator
      <div class="mt5 mb4">
        <label class="f5 ttu tracked db b mb2" for="js-side-count">
          Number of Sides
        <input class="b pa2 input-reset ba bw2 bg-white b--dark-gray w-100" 
               type="number" id="js-side-count" value="8">
      <div class="mv4">
        <label class="f5 ttu tracked db b mb2" for="js-radius">
        <input class="b pa2 input-reset ba bw2 bg-white b--dark-gray w-100"
               type="number" id="js-radius" value="200">
      <fieldset class="ba b--transparent pa0 mh0 mt4 mb5">
        <legend class="f5 ttu tracked db b mb2">Center</legend>
        <label class="f5 ttu tracked db b mb2 clip" for="js-cx">
          Center X Coordinate
        <label class="f5 ttu tracked db b mb2 clip" for="js-cy">
          Center Y Coordinate
        <div class="flex">
          <input class="b pa2 input-reset ba bw2 bg-white b--dark-gray w-100 mr3"
               type="number" id="js-cx" value="396">        
          <input class="b pa2 input-reset ba bw2 bg-white b--dark-gray w-100"
               type="number" id="js-cy" value="418">
      <input class="b pa3 input-reset ba b--dark-gray bw2 bg-white grow pointer f6 dib ttu tracked"
             id="js-generate" type="button" value="Generate">
  <div class="flex-auto flex items-center justify-center w-100">
    <div class="w-100">
      <svg class="w-100 white debug-grid mb4 db" viewBox="0 0 800 800" 
           stroke="#111" fill="none" stroke-width="4"
        <polygon id="js-polygon" points="" />

      <pre id="js-result" class="code pa3 bg-near-white mb0 overflow-scroll"></pre>
              pre { 
  overflow-wrap: break-word;
              const sideCountEl = document.querySelector('#js-side-count');
const radiusEl = document.querySelector('#js-radius');
const cxEl = document.querySelector('#js-cx');
const cyEl = document.querySelector('#js-cy');
const generateEl = document.querySelector('#js-generate');
const polygonEl = document.querySelector('#js-polygon');
const resultEl = document.querySelector('#js-result');
const svgEl = document.querySelector('#js-svg');

function pts(sideCount, radius) {
  const angle = 360 / sideCount;
  const vertexIndices = range(sideCount);
  const offsetDeg = 90 - ((180 - angle) / 2);
  const offset = degreesToRadians(offsetDeg);

  return => {
    return {
      theta: offset + degreesToRadians(angle * index),
      r: radius,

function range(count) {
  return Array.from(Array(count).keys());

function degreesToRadians(angleInDegrees) {
  return (Math.PI * angleInDegrees) / 180;

function polygon([cx, cy], sideCount, radius) {
  return pts(sideCount, radius)
    .map(({ r, theta }) => [
      cx + r * Math.cos(theta), 
      cy + r * Math.sin(theta),
    .join(' '); 

function generatePolygon() {
  const sideCount = +sideCountEl.value;
  const radius = +radiusEl.value;
  const cx = +cxEl.value;
  const cy = +cyEl.value;
  const s = 2 * radius + 50;

  const res = polygon([cx, cy], sideCount, radius);
  const viz = polygon([s / 2, s / 2], sideCount, radius);
  svgEl.setAttribute('viewBox', `0 0 ${s} ${s}`);
  polygonEl.setAttribute('points', viz);
  resultEl.innerText = `<polygon points="${res}" />`;

generateEl.onclick = generatePolygon;
window.onload = generatePolygon;
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