function setup() {

  createCanvas3D(windowWidth, windowHeight);

  background3D("#666")

  hideToolbox();

  sphere();

  button = createButton('click me');

  button.position(30, 30);

  button.mousePressed(toggleFullscreen);

}

​

function draw() {}

​

function toggleFullscreen() {

    let fs = fullscreen();

    fullscreen(!fs);

}

​

function windowResized() {

  resizeCanvas3D(windowWidth, windowHeight);

}