//////////////////// 定数 //////////////////////////////
int n = 100;

//////////////////// 変数 //////////////////////////////
int[] x;
int[] y;
int[] dx;
int[] dy;

//////////////////// 初期設定・準備 //////////////////////////////
void setup()
{
  size(640, 480);          // ウィンドウの作成
  ellipseMode(CENTER);
  fill(color(0, 0, 0));
  x = new int[n];
  y = new int[n];
  dx = new int[n];
  dy = new int[n];
  reset();
}

void draw(){
  for(int i = 0; i < n; i++){
    ellipse(x[i], y[i], 2, 2);
  }
  
  move();
  turn();
}

void move()
{
  for(int i = 0; i < n; i++){
    x[i] += dx[i];
    if(x[i] > width) x[i] = 0;
    y[i] += dy[i];
    if(y[i] > height) y[i] = 0;
  }  
}

void turn()
{
  for(int i = 0; i < n; i++){
    randomTurn(i); 
  }
}

void randomTurn(int i){
  if((int)random(100) == 0){
    dx[i] = int(random(3)) - 1;
    dy[i] = int(random(3)) - 1;
  }
  // 動いていなかったらもう一度抽選 
  if(dx[i] == 0 && dy[i] == 0) randomTurn(i);
}

void reset(){
  background(color(255, 255, 255));
  randomSeed(int(random(65536)));
  for(int i = 0; i < n; i++){
    x[i] = (int)random(width);
    y[i] = (int)random(height);
    dx[i] = int(random(3)) - 1;
    dy[i] = int(random(3)) - 1;
  }
}

void mouseReleased(){
  if(mouseButton == LEFT) reset();
}