Aleatoric lines

void setup() {
  size(650, 650);
  background(255);
}
void draw() {
  stroke(random(50, 100), random(100, 200), random(50, 100), 80);
  line(calc(1000, width), calc(1100, height), calc(1200, random(200, 400)*0.2), calc(1300, random(200, 400)*0.9));
}

float calc(float a, float b) {
  return abs(sin(millis()/a)*b);
}

void keyPressed() {
  if (key == 's') saveFrame("image-###.png");
}