// Daniel Shiffman

// http://natureofcode.com

​

// Perlin noise offset 

let yoff = 0;

// Random seed to control randomness while drawing the tree

let seed = 5;

​

​

function setup() {

  createCanvas(640,360);

}

​

function draw() {

  background(127);

  fill(0);

  //text("Click mouse to generate a new tree", 10, height-20);

​

  stroke(0);

  // Start the tree from the bottom of the screen

  translate(width/2, height);

  // Move alogn through noise

  yoff += 0.005;

  randomSeed(seed);

  // Start the recursive branching!

  branch(60, 0);

}

​

​

function mousePressed() {

  // New tree starts with new noise offset and new random seed

  yoff = random(1000);

  seed = millis();

}

​

​

function branch(h, xoff) {

  // thickness of the branch is mapped to its length

  let sw = map(h, 2, 100, 1, 5);

  strokeWeight(sw);

  // Draw the branch

  line(0, 0, 0, -h);

  // Move along to end

  translate(0, -h);

​

  // Each branch will be 2/3rds the size of the previous one

  h *= 2/3;

  // Move along through noise space

  xoff += 0.1;

​

  if (h > 4) {

    // Random number of branches

    let n = int(random(0, 5));

    for (let i = 0; i < n; i++) {

      // Here the angle is controlled by perlin noise

      // This is a totally arbitrary way to do it, try others!

      let theta = map(noise(xoff+i, yoff), 0, 1, -PI/3, PI/3);

      if (n%2==0) theta *= -1;

      push();      // Save the current state of transformation (i.e. where are we now)

      rotate(theta);     // Rotate by theta

      branch(h, xoff);   // Ok, now call myself to branch again

      pop();       // Whenever we get back here, we "pop" in order to restore the previous matrix state

    }

  }

}

​

​