float FADE_TIME = 120;
float OVERLAP = 9;
ArrayList revealers;

void setup() {
  size(800, 800);
  background(0);
  revealers = new ArrayList();
  initializeFades();
}

void draw() {
  background(255);
  for (int i = revealers.size ()-1; i >= 0; i --) {
    Revealer r = (Revealer) revealers.get(i);
    r.run();
  }
}

void initializeFades() {

  float a =3*PI/2;
  float rad = 25;
  float blockwidth = 9;

  for (int i=0; i<10; i++) {
    for (int j=0; j<10; j++) {
      float r, g, b;
      r = 200;
      g = 34;
      b = 90;
      float alpha = random(0, 255);

      float x1, y1, x2, y2, x3, y3, x4, y4;

      float increment = 2*PI/10;
      x1 = cos(a);
      y1 = sin(a);

      x2 = cos(a+increment);
      y2 = sin(a+increment);

      x3 = x2*(rad+blockwidth);
      y3 = y2*(rad+blockwidth);

      x4 = x1*(rad+blockwidth);
      y4 = y1*(rad+blockwidth);

      x1 *= rad;
      y1 *= rad;

      x2 *= rad;
      y2 *= rad;
      stroke(255);


      println(alpha);
      revealers.add(new Revealer(x1, y1, x2, y2, x3, y3, x4, y4, i*10*FADE_TIME/OVERLAP+j*FADE_TIME/OVERLAP, color(r, g, b, alpha)));


      a += 2*PI/10; //splitting the circle into 10 parts
    }
    rad += 12;
  }
}

class Revealer {
  PVector p1;
  PVector p2;
  PVector p3;
  PVector p4;
  float offset;
  color c;
  Revealer(float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4, float _offset, color _c) {

    p1 = new PVector(x1, y1);
    p2 = new PVector(x2, y2);
    p3 = new PVector(x3, y3);
    p4 = new PVector(x4, y4);
    offset = _offset;
    c = _c;
  }

  void run() {

    render();
  }


  void render() {
    //start at the middle
    pushMatrix();
    translate(width/2, height/2);
    noStroke();

    // we create a variable which will fade in and out our
    // shape. We assign it a value between 1 (full) and 0 (empty)
    // based on where we are relative to our start time
    // measured against FADE_TIME
    float fade = map(frameCount-offset, 0, FADE_TIME, 0, 1);

    //  we make sure it's not negative or greater than 1
    fade = constrain(fade, 0, 1);

    // we modify the alpha of our color based on fade, so now
    // it wil be blank at frameCount+offset frames, and fully
    // filled in by frameCount+offset+FADE_TIME frames

    fill(red(c), green(c), blue(c), alpha(c)*fade);

    //we draw our shape
    beginShape();

    vertex(p1.x, p1.y);
    vertex(p2.x, p2.y);
    vertex(p3.x, p3.y);
    vertex(p4.x, p4.y);

    endShape();

    popMatrix();
  }
}