Generates a Megagon SVG

megagon.js

#!/usr/bin/env node
'use strict';

var size = 10000;
var sides = 1000000;
var padding = 50;

var path = polygon(size / 2 + padding, size / 2 + padding, size / 2, sides)
           .map(function (p) { return p.x + ',' + p.y; })
           .join(' ');

process.stdout.write('\
<?xml version="1.0" standalone="yes"?>\n\
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"\n\
  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">\n\
  <svg width="1000" height="1000" viewBox="0 0 ' + (size + padding * 2) + ' ' + (size + padding * 2) + '"\n\
       xmlns="http://www.w3.org/2000/svg" version="1.1">\n\
    <polygon style="fill:none;stroke:#000000;stroke-width:2.5px"\n\
             points="' + path + '" />\n\
</svg>\n\
');


/**
 * calculate regular polygon coordinates
 * @returns {Point[]}
 */
function polygon(center_x, center_y, radius, sides) {
    var start_angle, center_angle, vertices;

    sides = Math.round(sides);
    center_angle = 2 * Math.PI / sides;

    if (sides % 2 === 1) {
        start_angle = Math.PI / 2;  // 12 o'clock
    } else {
        start_angle = Math.PI / 2 - center_angle / 2;
    }

    return times(sides, function (i) {
        var angle = start_angle + (i * center_angle);
        return new Point(
            get_x(center_x, radius, angle),
            get_y(center_y, radius, angle)
        );
    });
}

function times(n, iterator) {
  var accum = Array(Math.max(0, n));
  for (var i = 0; i < n; i++) accum[i] = iterator.call(undefined, i);
  return accum;
}
function Point(x, y) {
    this.x = x;
    this.y = y;
}
function get_x(center_x, radius, angle) {
    return center_x + radius * Math.cos(angle);
}

function get_y(center_y, radius, angle) {
    return center_y - radius * Math.sin(angle);
}