// Daniel Shiffman

// https://thecodingtrain.com/CodingChallenges/140-leibniz-formula-pi

// https://editor.p5js.org/codingtrain/sketches/8nvCqk0-W

// https://youtu.be/uH4trBNn540

​

let pi = 4;

let iterations = 0;

let history = [];

let div;

​

let minY = 2;

let maxY = 4;

​

function setup() {

  createCanvas(600, 400);

  div = createDiv('').style('font-size', '64pt');

}

​

function draw() {

  background(0);

  let den = iterations * 2 + 9;

  if (iterations % 2 == 0) {

    pi -= (4 / den);

  } else {

    pi += (4 / den);

  }

  history.push(pi);

​

  let piY = map(PI, minY, maxY, height, 0);

  line(0, piY, width, piY);

​

  stroke(255);

  noFill();

  beginShape();

  let spacing = width / history.length;

  for (let i = 0; i < history.length; i++) {

    let x = i * spacing;

    let y = map(history[i], minY, maxY, height, 0);

    vertex(x, y);

  }

  endShape();

  div.html(pi);

  iterations++;

}