Cubed sines

float y, theta, rad;
int num = 30;
color bg= #000000;

void setup() {
  size(500, 300);
  background(bg);
  noFill();
  theta=0;
}

void draw() {
  background(0);
  for (int i=0; i < num; i++) {
    strokeWeight(random(20, 40));
    rad = random(50, 60);
    stroke((255/num)*i, 200);
    float starty = height/2 + random(-10, 10);
    beginShape();
    for (int x=int(random(-3,3)); x< width; x++) {
      y = starty+ (pow(sin(theta), 3)*rad);
      curveVertex(x, y);
      theta += .03;
    }
    endShape();
  }

  if (frameCount > 100) saveFrame("line-###.gif");
}

void mouseClicked() {
  save(random(123) + ".jpg");
}