superEllipse

float theta;
float n = 0, a, b;
int frms = 120, num = 25;

void setup() {
  size(750, 540);
}

void draw() {
  background(51);

  translate(width/2, height/2);

  noFill();
  stroke(238, 150);

  for (int i=0; i<num; i++) {
    float offSet = PI/3/num*i;
    n = map(sin(theta+offSet), -1, 1, 0.1, 3);
    a = map(sin(theta), -1, 1, 100, 200);
    b = a;
    beginShape();
    for (float angle = 0; angle<TWO_PI; angle+= 0.1) {
      float na = 2/n;
      float x = pow(abs(cos(angle+offSet)), na)*a*sgn(cos(angle));
      float y = pow(abs(sin(angle+offSet)), na)*b*sgn(sin(angle));
      vertex(x, y);
    }
    endShape(CLOSE);
  }

  theta += TWO_PI/frms;
  if (frameCount <= frms) saveFrame("image-###.gif");
}

int sgn(float val) {
  if (val>0) {
    return 1;
  } else if (val<0) {
    return -1;
  } else {
    return 0;
  }
}