Polygon Bounds by HarryStevens

index.html

<!DOCTYPE html>
<html>
<head>
  <style>
    body {
      margin: 0;
    }
    .polygon {
      fill: steelblue;
    }
    .bounds {
      fill: none;
      stroke: black;
      stroke-width: 2px;
    }
  </style>
</head>
<body>
  <script src="https://d3js.org/d3.v5.min.js"></script>
  <script src="https://unpkg.com/geometric@1.0.11/build/geometric.min.js"></script>
  <script>
    var width = window.innerWidth,
        height = window.innerHeight,
        center = [width / 2, height / 2],
        vertices = [
          [center[0] - 100, center[1] - 100],
          [center[0], center[1] - 130],
          [center[0] + 100, center[1] - 100],
          [center[0] + 150, center[1]],
          [center[0] + 100, center[1] + 100],
          [center[0], center[1] + 130],
          [center[0] - 100, center[1] + 100],
          [center[0] - 150, center[1]]
        ];

    var input = d3.select("input");

    var svg = d3.select("body").append("svg")
        .attr("width", width)
        .attr("height", height);

    var polygon = svg.append("polygon")
        .attr("class", "polygon")
        .attr("points", vertices.join(" "));

    var bounds = svg.append("polygon")
        .attr("class", "bounds")
        .attr("points", geometric.polygonBounds(vertices).join(" "));
  </script>
</body>
</html>