tree.js

function setup()
{ 
  createCanvas(700, 500);
  background(220);
  strokeWeight(10);
}

function transform(shape, angle, factor)
{
  shape.x += shape.size * Math.cos(shape.angle);
  shape.y += shape.size * Math.sin(shape.angle);
  shape.angle += angle;
  shape.size *= factor;
}

var angle1 = Math.random();
var angle2 = -Math.random();
var factor1 = 0.3 * Math.random() + 0.55;
var factor2 = 0.3 * Math.random() + 0.55;

function draw()
{ 
  var shape = { x:350, y:400, angle:-Math.PI/2, size:80 };
  
  for (var i = 0; i < 12; ++i)
  {
    if (i < 11)
    {
      var x2 = shape.x + shape.size * Math.cos(shape.angle);
      var y2 = shape.y + shape.size * Math.sin(shape.angle);
      stroke(100,50,0);
      strokeWeight(shape.size/10);
      line(shape.x, shape.y, x2, y2);
    }
    else
    {
      stroke(0,150,0);
      fill(0,255,0);
      ellipse(shape.x,shape.y,shape.size);
    }
    
    if (Math.random() < 0.5)
    {
      transform(shape, angle1, factor1);
    }
    else
    {
      transform(shape, angle2, factor2);
    }
  }
}