idunno

int num =20;

float step, sz, offSet, theta, angle;

void setup() {

  size(600, 450);

  strokeWeight(5);

  step = 22;

}

void draw() {

  background(250);

  translate(width/2, height*.75);

  angle=0;

  for (int i=0; i<num; i++) {

    //stroke((255-i)%100,(255*i)%100,(cos(i)*255)%100);

    stroke((cos((i*i)-i)*255)%255,(cos(i)*255)%255,(cos(i+1)*255)%255);

    noFill();

    sz = i*step;

    float offSet = PI/sin(i)/i;

    float arcEnd = map(tan(theta+offSet)*i-cos(theta-offSet),-1,1, TWO_PI-i, (TWO_PI*PI)-i);

    arc(0, -100, sz, sz, PI, arcEnd);

  }

  colorMode(RGB);

  resetMatrix();

  theta += .0523;

  theta += 0.005;

}

​