mento-calor-method.js

// Author: Huahua (https://www.youtube.com/user/xxfflower)
// p5 web editor: https://editor.p5js.org
var w = 400;
var h = 400;
var img;
var sampled = 0;
var valid = 0;

function setup() {  
  createCanvas(w, h);
  img = createImage(w, h);
}

function computeIntegral(n) {
  sampled += n;
    
  var r = color(255, 0, 0);
  var b = color(0, 0, 255);
  
  for (var i = 0; i < n; ++i) {
    var x = random();
    var y = random();

    var sx = floor(x  * w);
    var sy = h - floor(y * h);
    if (x * x >= y) {
      img.set(sx, sy, r);
      ++valid;
    } else {
      img.set(sx, sy, b);
    }
  }
  img.updatePixels();
  
  return valid / sampled;
}

function computePI(n) {
  sampled += n;
    
  var r = color(255, 0, 0);
  var b = color(0, 0, 255);
  
  for (var i = 0; i < n; ++i) {
    var x = random() * 2 - 1;
    var y = random() * 2 - 1;

    var sx = floor((x / 2 + 0.5) * w);
    var sy = floor((y / 2 + 0.5) * h);
    if (x * x + y * y <= 1.0) {      
      img.set(sx, sy, r);
      ++valid;
    } else {
      img.set(sx, sy, b);
    }
  }
  img.updatePixels();
  
  return valid / sampled * 4;
}

function draw() {
  background(255);
  var value = computePI(100);
  // var value = computeIntegral(100);
  image(img, 0, 0);
  console.log("sampled = " + sampled + " value = " + value);
}