211113rect_superellipse.js

function setup() {
  createCanvas(800, 400);
  angleMode(DEGREES);
}

function draw() {
  background(220);

  let d = width / 4;  
  textAlign(CENTER,CENTER);
  push();
  translate((width * 1) / 4, height / 2);
  rectMode(CENTER);
  rect(0, 0, d, d, d / 4);
  text("rect(0, 0, d, d, d / 4)",0,height/3);
  pop();

  push();
  translate((width * 3) / 4, height / 2);
  rectMode(CENTER);
  drawSuperEllipse(0, 0, d, d, 5);
  text("drawSuperEllipse(0, 0, d, d, 5)",0,height/3);
  pop();
}
function drawSuperEllipse(x, y, w, h, n = random(1.5, 5)) {
  push();
  translate(x, y);
  let na = 2 / n;
  beginShape();
  for (let angle = 0; angle < 360; angle += 1) {
    let nx = ((pow(abs(cos(angle)), na) * w) / 2) * sgn(cos(angle));
    let ny = ((pow(abs(sin(angle)), na) * h) / 2) * sgn(sin(angle));
    vertex(nx, ny);
  }
  endShape(CLOSE);
  pop();
}

function sgn(val) {
  if (val == 0) {
    return 0;
  }
  return val / abs(val);
}