Thing[] th; 
float rad;
float mx, my, mxold, myold, activity, movelimit;
float[] all_active = new float[10];
int arr_count=0;

int num = 20;

float unit = sqrt(num);


void setup (){
  size(400,400);
  background(150);
  rectMode(CENTER_DIAMETER);
  framerate(60);
  noStroke();
  
  rad = width/unit;
  movelimit = 20;
  
  float xnow, ynow;
  xnow=ynow=rad/2;
  
  th = new Thing[num];
  
  for(int i=0;i<num;i++){
    th[i] = new Thing(xnow, ynow);
    th[i].paint();
    xnow+=rad;
    if(xnow>=width){
    xnow=rad/2;
    ynow+=rad;
    }
  }
}


void loop(){
  background(150);
  for(int i=0;i<num;i++){
    th[i].move();
  }
  mx = mouseX;
  my = mouseY;
  
  activity = sqrt(((mx-mxold)*(mx-mxold))+((my-myold)*(mx-mxold)))+1;
  mxold = mx;
  myold = my;
  all_active[arr_count]=activity;
  arr_count++;
  if(arr_count>=all_active.length-1) arr_count=0;
  float all=0;
  for(int g=0;g<all_active.length;g++){
  all+=all_active[g];
  }
  activity = all/all_active.length;
 // println(activity);
  
}


class Thing{
  float xpos, ypos, orderx, ordery, moving;

//Constructor
  Thing(float x, float y){
    orderx = xpos=x;
    ordery = ypos=y;
    moving = 5;
  }
  void paint(){
  rect(orderx+random(-moving,moving),ordery+random(-moving,moving),rad,rad);
  }
  void move(){
    moving = (movelimit/activity);
    paint();
  }
}