Tree root;

ArrayList<Tree> fullTree = new ArrayList<Tree>();

void setup() {
  fullScreen();
  PVector a = new PVector(width/2, height);
  PVector b = new PVector(width/2, height - 100);
  root = new Tree(a, b, PI/10, 20);
  background(51);
  root.show();

}

//void draw() {
//  background(51);
//}


class Tree {

  private PVector start, end;
  private float angle;
  private int depth;
  private Tree left, right;


  public Tree(PVector start, PVector end, float angle, int depth) {
    this.start = start;
    this.end = end;
    this.depth = depth;
    this.angle = angle;
    if (this.depth >= 0) {
      this.left = this.branch("left");
      this.right = this.branch("right");
    }

  }

  public void show() {
    stroke(255);
    line(this.start.x, this.start.y, this.end.x, this.end.y);
    if (this.depth > 0) {
      this.left.show();
      this.right.show();
    }

  }

  public Tree branch(String direction) {
    int sign = -1;
    if (direction.equals("right")) {
      sign *= sign;
    }
    PVector dir = PVector.sub(this.end, this.start);
    dir.rotate(sign * this.angle);
    dir.mult(.82);
    PVector newEnd = PVector.add(this.end, dir);
    return new Tree(this.end, newEnd, this.angle, this.depth - 1);
  }


}