Curves with Lines

var x1 = 0, y1 = 0, x2 = 5, y2 = 400;
var x12 = 400, y12 = 400, x22 = 395, y22 = 0;
function setup() {
  createCanvas(400, 400);
  background(0);
}

function draw() {
  if (y1 < 400){
    stroke(255, 200, 100)
    line(x1,y1,x2,y2)
    y1 = y1+5;
    x2 = x2+5;
  }
  if (x22>0){
    stroke(255, 200, 100)
    line(x12,y12,x22,y22)
    x22 = x22-5;//change the x coordinate
    y12 = y12 - 5;//change the y coordinate
  }
  else{noLoop()}//stops when done drawing
}