Circles in Circles moving to give the illusion of spirals

circlesTunnelSpiral.pde

//visual output: https://twitter.com/VolfeganGeist/status/1205621889416208384
//reference code for some of the effects used: https://twitter.com/ky0ju_art/status/1175391601121611776
//attempt to recreate: https://twitter.com/Borrachas/status/1204855395006763009
float a, b, c=0, x, y, d, r=600*2, h=600/2, s=40;
void setup() {
  size(600, 600);
}
void draw() {
  background(#EFF2D0);
  for (x=0; x<=r; x+=s*2) {
    for (y=0; y<=r; y+=s*2) {
      d=norm(dist(h, h, x, y), h, 0);
      fill(0, d*20);
      strokeWeight(abs(d*2));
      b=cos(s+a)*((pow(1.0081,x)/y)+(x+y+log(abs(c)))/64);
      c=sin(s+a)*(log(s*x+y)+(pow(1.0017, x)*x)/s);
      circle(h+b, h+c, x);
      a+=.1;
    }
  }
  fill(0);
  circle(h+cos(s+a)*s/8, h, s);
}