// Based on Listing 5.1, Generative Art
float xstart, xnoise, ystart, ynoise;

void setup() {
  size(300, 300);
  background(255);
  xstart = random(10);
  ystart = random(10);
}

void draw() {
  xstart += 0.01;   
  ystart += 0.01;  

  ynoise = ystart;
  for (int y = 0; y <= height; y++) {  
    ynoise += 0.01;
    xnoise = xstart;           
    for (int x = 0; x <= width; x++) {  
      xnoise += 0.01;
      set(x, y, color(255*noise(xnoise, ynoise)));
    }
  }
}