Reveal.initialize({
  controls: false,
  math: {
    mathjax: 'node_modules/mathjax/MathJax.js',
    config: 'TeX-AMS_HTML-full',
    // pass other options into `MathJax.Hub.Config()`
    TeX: {Macros: {RR: "{\\bf R}"}}
  },

  hash: true,
  dependencies: [
    {src: 'plugin/markdown/marked.js'},
    {src: 'plugin/markdown/markdown.js'},
    {src: 'plugin/highlight/highlight.js'},
    {src: 'plugin/math/math.js', async: true},
    {src: 'plugin/notes/notes.js', async: true}
  ]
});


/******************
 * KOCH ANIMATION *
 ******************/
const canvas = document.getElementById("koch");
const ctr = document.getElementById("iterationCtr");
const ctx = canvas.getContext("2d");

canvas.width = window.innerWidth * 0.9;
canvas.height = window.innerHeight * 0.9;
const cx = canvas.width / 2;
const cy = canvas.height / 2;
ctx.translate(cx, cy);
ctx.fillStyle = "#191919";
ctx.lineWidth = 4;
ctx.fillRect(-cx, -cy, 2 * cx, 2 * cy);
ctx.strokeStyle = "white";
koch([-cx, 100], [cx, 100], 0);

window.onkeyup = event => {
  switch (event.key) {
    case "1":
    case "2":
    case "3":
    case "4":
    case "5":
    case "6":
    case "7":
      ctr.innerText = event.key;
      ctx.fillRect(-cx, -cy, 2 * cx, 2 * cy);
      koch([-cx, 100], [cx, 100], Number(event.key) - 1);
  }
};

// Recursion!
function koch(start, end, iteration) {
  const x1 = (end[0] - start[0]) / 3 + start[0];
  const y1 = (end[1] - start[1]) / 3 + start[1];
  const x2 = (end[0] - start[0]) * 2 / 3 + start[0];
  const y2 = (end[1] - start[1]) * 2 / 3 + start[1];
  const x3 = ((x1 + x2) + Math.sqrt(3) * (-y1 + y2)) / 2;
  const y3 = ((y1 + y2) + Math.sqrt(3) * (x1 - x2)) / 2;

  ctx.beginPath();

  ctx.moveTo(start[0], start[1]);
  ctx.lineTo(x1, y1);
  ctx.moveTo(x2, y2);
  ctx.lineTo(end[0], end[1]);

  ctx.moveTo(x1, y1);
  ctx.lineTo(x3, y3);
  ctx.moveTo(x2, y2);
  ctx.lineTo(x3, y3);
  ctx.closePath();
  ctx.stroke();

  ctx.strokeStyle = "#191919";
  ctx.beginPath();
  ctx.moveTo(x1, y1);
  ctx.lineTo(x2, y2);
  ctx.closePath();
  ctx.stroke();
  ctx.strokeStyle = "white";

  if (iteration > 0) {
    koch([start[0], start[1]], [x1, y1], iteration - 1);
    koch([x1, y1], [x3, y3], iteration - 1);
    koch([x3, y3], [x2, y2], iteration - 1);
    koch([x2, y2], [end[0], end[1]], iteration - 1);
  }
}