ParabolaSym

 
var cnt =-60;//counter
var p = -200;
function setup() {
  createCanvas(400, 400);
  background(25);
  stroke(25);//gray background so first circle isn't seen
  fill(25);//gray background
  newABC();//initialize variables for drawing
  strokeWeight(0.5);//thin lines
  fill(255,30);//setting fill for circles to be transparent
}

function draw() {
  translate(width/2,width/2)
  stroke(50-cnt,200+cnt*2,255);//create a gradient color based on x value;
  y1 = (-a1*pow(cnt,2) +b1*cnt+c1)/150
  y2 = (-a2*pow(cnt,2) +b2*cnt+c2)/600
  line(cnt*5,y1,cnt,y2)//draw line between points of both parabolas
  cnt=cnt+1;
  if (cnt>60){//draw a new set of parabolas
    newABC();//calculate new a,b,and c values for parabolas
  }
}
function newABC(){
  circle(0,p,5)//draw artistic circles as timers for animation
  circle(0,-p,15)
  a = random(-1,1)//makes both parabolas face the same direction
  a1 = random(-200,200)*a;//random a,b, and c variables:
  b1 = random(-20,20)
  c1 = random(-8000,8000)
  a2 = random(-200,200)*a;
  b2 = random(-20,20)
  c2 = random(-8000,8000)
  cnt = -60;//reset cnt
  p = p+10;//increase circle counter and reset
  if (p>210){//reset after the circle gets to the end
    p = -200;
    background(25);
  }
}