void setup(){
  int x = 5;
  Point[] points = new Point[x*3];
  Point[] points1 = new Point[x];
  Point[] points2 = new Point[x];
  Point[] points3 = new Point[x];
  
  // define the 1,2,3 arrays in a loop
  for(int i=0; i<4; i++){
    points1[i] = new Point(random(3), random(3));
    points2[i] = new Point(random(3), random(3));
    points3[i] = new Point(random(3), random(3));
  }
  
  points = concat(points1, points3, points2);
}

class Point{
   float x, y;
   Point(float x, float y){
      this.x = x;
      this.y = y;
   }
}