create 5 curves and apply a fourier transform

void setup() {
  size(640, 360);
  noStroke();
  background(0);
  
  float d = random(10, width/5);
  float d2 = random(d, 2*d); 
  float d3 = random(d2, 3*d); 
  float d4 = random(d3, 4*d);
  float d5 = random(d4, 5*d); 
  
  beginShape();
  float xoff = 0;
  for (float x = 0; x <= width; x += 10) {
    float y = map(noise(xoff, yoff), 0, 1, 200,300);
    vertex(x, y); 
    xoff += 0.05;
    if (x > d && x < d2) {
      yoff += 0.01;
    } 
    else if (x > d2 && x < d3) {
      yoff += 0.02;
    } 
    else if (x > d3 && x < d4)