createPlane = function(u, v){
      var x = 2 * width * u - width;
      var y = 2 * height * v - height;
      var z = 0;
      return new p5.Vector(x, y, z);
    }
draw a sphere with given raduis
@param  {Number} radius            radius of the sphere
@param  {Number} detailX(optional) number of vertices on horizontal surface
@param  {Number} detailY(optional) number of vertices on vertical surface
example
<div class="norender">
<code>
function setup(){
  createCanvas(windowWidth, windowHeight, 'webgl');
}

var theta = 0;

function draw(){
  background(255, 255, 255, 255);
  translate(0, 0, -100);
  push();
  rotateZ(theta);
  rotateX(theta);
  rotateY(theta);
  sphere(100);
  pop();
  theta += 0.05;
</code>
</div>