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

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

void draw() {
  // control spatial increment with mouseX
  dxy = map(mouseX, 0, width, 0.001, 0.05); 
  // control temporal increment with mouseY
  dt = map(mouseY, 0, height, 0.001, 0.05); 

  ynoise = ystart;

  tnoise += dt;

  for (int y = 0; y <= height; y+=1) {
    ynoise += dxy;
    xnoise = xstart;
    for (int x = 0; x <= width; x+=1) {
      xnoise += dxy;
      set(x, y, color(255*noise(xnoise, ynoise, tnoise)));
    }
  }
}

void mouseMoved () {
    println("dxy:"+dxy+" dt:"+dt);
}