t

void setup() {
  size(600, 600);
  noStroke();
  // noSmooth();
}
float t;
color a = #FA003F;
int frames = 600;
float radius = 70;
int size = 200;
color back = #2D3339;
int num = 13;
float ss = ((2 * PI * size) / num) * 0.9;
float theta = 0;
void draw() {
  t = (frameCount%frames)/(float)frames;
  // VERY CRUDE HERE
  if ((frameCount%frames)==0) {
    fill(random(255), random(255), random(255));
  }
  background(back);
  translate((int)width/2, (int)height/2);
  pushMatrix();
  rotate(theta);
  program();
  popMatrix();
}

void a() {
  fill(a);
}

void program() {
  if ( t < 0.5) {

    float tt = map(t, 0, 0.5, 0, 1);
    // FIRST QUARTER
    if (tt < 0.5) {
      for (int i = 0; i < num; i++) {
        pushMatrix();
        float r = map(tt, 0, 0.5, ss, 0);

        float move = map(i, 0, num, 0, TWO_PI);
        rotate(move);
        translate(size, 0);
        rotate(PI/2);
        arc(0, 0, ss, r, 0, PI);
        arc(0, 0, ss, ss, PI, TWO_PI); //doesn't move
        popMatrix();
      }
    }
    // SECOND QUARTER
    else {

      for (int i = 0; i < num; i++) {
        pushMatrix();
        float move = map(i, 0, num, 0, TWO_PI);
        rotate(move);
        translate(size, 0);
        rotate(PI/2);
        float r = map(tt, 0.5, 1, 0, ss);
        arc(0, 0, ss, ss, PI, TWO_PI); // doesn't move
        fill(back);
        arc(0, 0, ss, r, PI, TWO_PI);
        fill(255);
        popMatrix();
      }
    }
  }
  // HALF TWO
  else {
    float tt = map(t, 0.5, 1, 0, 1);
    if (tt < 0.5) {
      for (int i = 0; i<num; i++) {
        pushMatrix();
        float move = map(i, 0, num, 0, TWO_PI);
        rotate(move);

        translate(size, 0);
        rotate(PI/2);
        float r = map(tt, 0, 0.5, ss, 0);
        fill(255);
        arc(0, 0, ss, ss, PI, TWO_PI);
        fill(back);
        arc(0, 0, ss, r, PI, TWO_PI);
        popMatrix();
      }
    } else {
      for (int i=0; i<num; i++) {
        pushMatrix();
        float move = map(i, 0, num, 0, TWO_PI);
        rotate(move);
        translate(size, 0);
        rotate(PI/2);
        float r = map(tt, 0.5, 1, 0, ss);
        fill(255);
        arc(0, 0, ss, ss, PI, TWO_PI);
        arc(0, 0, ss, r, 0, PI);
        fill(255);
        popMatrix();
      }
    }
  }
}