int num = 100;
Bug[] buf_bugs;
Bug[][] bugs;

void setup()
{
  size(2*num, 2*num);
  fill(255);
  bugs = new Bug[num][num];
  buf_bugs = new Bug[8]; 
  
  for(int x = 0; x < num; x++){
    for(int y = 0; y < num; y++){
      bugs[x][y] = new Bug(2*x, 2*y);
    }
  }
  frameRate(1);
}

void draw()
{
  background(0);
  int[] idx_buf;
  int x_m, x_p, y_m, y_p;
  for(int x = 0; x < num; x++){
    for(int y = 0; y < num; y++){
      x_m = v(x - 1); 
      x_p = v(x + 1); 
      y_m = v(y - 1); 
      y_p = v(y + 1);
      buf_bugs[0] = bugs[x_m][y_m];
      buf_bugs[1] = bugs[x][y_m];
      buf_bugs[2] = bugs[x_p][y_m];
      buf_bugs[3] = bugs[x_m][y];
      buf_bugs[4] = bugs[x_p][y];
      buf_bugs[5] = bugs[x_m][y_p];
      buf_bugs[6] = bugs[x][y_p];
      buf_bugs[7] = bugs[x_p][y_p];
      
      bugs[x][y].update(buf_bugs);
    }
  }
  for(int x = 0; x < num; x++){
    for(int y = 0; y < num; y++){
      bugs[x][y].draw();
    }
  }
}

int v(int i){
  if(i >= 0){
    if(i < 100){
      return i;
    }else{
      return 0;
    }
  }else{
    return 99; 
  }
}

class Bug {
  int idx, idy;
  int live_flag, buf_live_flag;
  int bug_color = 0;
  Bug(int x, int y){
    idx = x;
    idy = y;
    buf_live_flag = live_flag = (random(0, 10) < 1) ? 1 : 0;
  }
  public int living(){
    return buf_live_flag;
  }
  public void update(Bug[] bugs){
    int count_living = 0;
    for(int i = 0 ; i < 8 ; i++){
      count_living += bugs[i].living();
    }
    if(live_flag == 1 && (count_living < 2 || count_living > 3)){
      live_flag = 0;  
    }else if(live_flag == 0 && count_living == 3){
      live_flag = 1;
    }
  }
  public void draw(){
    bug_color = (live_flag == 1) ? 255 : 0;
    fill(bug_color);
    rect(idx, idy, idx+2, idy+2);
    buf_live_flag = live_flag;    
  }
}