My implementation of a Koch Snowflake plot using Processing

koch_snowflake.pde

void setup() {
  size(600, 600);
}

void draw() {
  background(#ffffff);
  int steps = 4; 
  PVector a = new PVector(100, 200);
  PVector b = new PVector(500, 200);
  PVector c = PVector.add(a, PVector.sub(b, a).rotate(radians(60)));
  
  step(a, b, steps);
  step(b, c, steps);
  step(c, a, steps);
}

void step(PVector a, PVector b, int depth) {
  if (depth > 0) {
    PVector ab = PVector.sub(b, a).mult(1 / 3f);
    PVector ap = PVector.add(a, ab);
    PVector bp = PVector.sub(b, ab);
    PVector c =  PVector.add(ap, ab.copy().rotate(- radians(60)));

    step(a, ap, depth - 1);
    step(ap, c, depth - 1);
    step(c, bp, depth - 1);
    step(bp, b, depth - 1);
  } else {
    stroke(#000000);
    line(a.x, a.y, b.x, b.y);
  }
}