Hi all!  I designed my program so that the circles inside the applet will move 80 pixels in length when I hold down the mouse.  The circles move around randomly across the screen, but the circles should overlap perfectly with one another.  I am getting a bug where if I hold down the mouse button for a bit the circles deviate from its 80 pixels restriction... to 79 78 77 etc.... does anyone know what is going on and also how to resolve this?

here's the code:

int count = 70;
Thing[]things = new Thing[count];

void setup(){
 background(0);
 size(640, 800);
 frame.setResizable(true);
 frameRate(20);
 
 
 for(int i = 0; i < things.length; i++){
   things[i] = new Thing(40,40, int(random(100,210)), 250, 40);
 }
}

void draw(){
 background(0);
 noFill();
 rect(0, 0, width, height);
 for(int i = 0; i < things.length; i++){
   things[i].display();
   
   if(mousePressed == true){
     things[i].move();
     println(things[i].x);
     println(things[i].y);
  }
 }
}

class Thing{
 float x, y;
 int r;
 int g;
 int b;
 int vd = 80;
 int opacity = 100;
 int diameter = 80;

 Thing(int xpos, int ypos, int rr, int gg, int bb){
   x = xpos;
   y = ypos;
   r = rr;
   g = gg;
   b = bb;
 }
 void display(){
   fill(r, g, b, opacity);
   smooth();
   noStroke();
   //ellipseMode(CORNER);
   ellipse(x, y, diameter, diameter);  
 }
 
 void move() {
   int t = int(random(-2, 2));
   int v = int(random(2));
   
   if(v == 0){
     x += vd*t;
     println("5");
     println(v);
     println(t);

   }else if(v==1){
     y += vd*t;
     println("6");
     println(v);
     println(t);
   }
   
   if (x + diameter/2 > width) {
     x = width - diameter/2;
     vd += -1;
     println("1");
   }
   else if (x - diameter/2 < 0) {
     x = diameter/2;
     vd *= -1;
     println("2");
   }
   if (y + diameter/2 > height) {
     y = height - diameter/2;
     vd *= -1;
     println("3");
   }
   else if (y - diameter/2 < 0) {
     y = diameter/2;
     vd *= -1;
     println("4");
   }
 }
}
 
 
 


 

Thank you!