// Daniel Shiffman

// http://patreon.com/codingtrain

// Code for: https://youtu.be/0jjeOYMjmDU

​

// Modified slightly by Thomas

​

var angle = 0;

​

// change the speed of the color changing effect

var colorShift = 0.4;

var slider;

​

var tree;

// produced by each call to next() on the generator

var nextObject;

​

// used to loop the animation and set it up

function resetTree() {

  tree = branch(100);

  nextObject = null; 

  background(51, 0, 14);

}

​

function setup() {

  createCanvas(400, 400);

  colorMode(HSB);

  slider = createSlider(0, TWO_PI, PI / 4, 0.01);

  slider.input(() => {

    resetTree();

  })

  resetTree();

​

}

​

function draw() {

  angle = slider.value();

  stroke(255);

  translate(200, height);

  if (!nextObject || !nextObject.done) {

    nextObject = tree.next()

  } else {

    print(frameCount);

    resetTree();

  }

}

​

// starting hue = 1

let hu = 1

function* branch(len) {

  line(0, 0, 0, -len);

  translate(0, -len);

  if (len > 4) {

    push();

    rotate(angle);

    stroke(hu = (hu + colorShift) % 360, 100, 100);

    yield* branch(len * 0.67);

    pop();

    push();

    rotate(-angle);

    stroke(hu = (hu + colorShift) % 360, 100, 100);

    yield* branch(len * 0.67);

    pop();

  }

  yield

}

​