void setup() {
  size(400, 400);
  frameRate(15);
}

void draw() {
  background(255);
  
  // Hintergrundlinien
  // Farbe abh. von Mausposition
  if (mouseX < 255) {
    for (int i = 0; i <= 100; i++) {
      stroke(mouseX);
      strokeWeight(random(10));
      line(random(width), random(height), random(width), random(height));
    }
  }
  
  // Vordergrundlinien
  for (int i = 0; i <= 10; i++) {
    stroke(random(255));
    strokeWeight(random(10));
    line(random(width), random(height), random(width), random(height));
  }
}