void setup(){
  size(800,600);
  noLoop();
}

void draw(){
  for( int i = 0; i < width; i++ ){
    for ( int j = 0; j < height; j++ ){
      int c = int(255 * pattern(new PVector(i,j)));
      set( i, j, c<<16|c<<8|c|0xff000000 );
    }
  }
}

float pattern( PVector p ){
  PVector q = new PVector( fbm( PVector.add(p, new PVector(0.0,0.0))), fbm( PVector.add( p, new PVector(5.2,1.3) ) ) );
  q.mult(4.0);
  p.add( q );
  return fbm( p );
}

float fbm( PVector p ){
      float total = 0;
      float frequency = 1.0/100;
      float lunacity = 2.0;
      float amplitude = 0.5;
      float gain = 0.5;
      for ( int k = 0; k < 4; k++ ){
        total += noise(p.x*frequency, p.y*frequency)*amplitude;
        frequency *= lunacity;
        amplitude *= gain;
      }
      return total;
}