var angle;

var level = 0;

var stWeight = 4;

​

function setup(){

  createCanvas(400, 400);

  angle = 0;

}

​

function draw(){

  background('#007FFC');

  stWeight = 4;

  level = 0;

  strokeWeight(stWeight);

  translate(width/2, height);

  angle = map(sin(frameCount/20 + HALF_PI), -1, 1, PI/20, PI - PI/4);

  branch(len);

​

​

}

​

function branch(len){

  translate(0, -len);

  stroke(level * 10, level * 20, level * 7);

  line(0, 0, 0, len);

  if(level < 10){

    pushIX();

    rotate(angle);

    branch(len * 2/3);

    popIX();

    pushIX();

    rotate(-angle);

    branch(len * 2/3);

    popIX();

  }

}

​

function pushIX(){

  push();

  level ++;

  stWeight -= 0.4;

  strokeWeight(max(stWeight, 0.1));

}

​

function popIX(){

  pop();

  level --;

  stWeight += 0.4;

  strokeWeight(max(stWeight, 0.1));

}

​