// Two ball variables
  Ball ball1;
  Ball ball2;
  Ball ball3;
  Ball ball4;
  Ball ball5;
  
  void setup() {
    size(400,400);
    framerate(50);
    smooth();
    // Initialize balls
    ball1 = new Ball(64);
    ball2 = new Ball(32);
    ball3 = new Ball(48);
    ball4 = new Ball(85);
    ball5 = new Ball(18);
    }
    
  void draw() {
    background(255,0,0);
    //Move and display balls
    ball1.move();
    ball2.move();
    ball3.move();
    ball4.move();
    ball5.move();
    boolean intersecting = ball1.intersect(ball2); 
                           ball2.intersect(ball3);
                           ball3.intersect(ball1);
                           ball4.intersect(ball2);
                           ball4.intersect(ball3);
                           ball5.intersect(ball1);
                           ball5.intersect(ball2);
                           ball5.intersect(ball3);
                           ball5.intersect(ball4);
                           ball4.intersect(ball1);
    if (intersecting) {
      ball1.highlight();
      ball2.highlight();
      ball3.highlight();
      ball4.highlight();
      ball5.highlight();
      }
    ball1.display();
    ball2.display();
    ball3.display();
    ball4.display();
    ball5.display();
     
    }
    
    
    
  class Ball {
    float r;        // radius
    float x,y;
    float xspeed,yspeed;
    color c = color(255,50);
    
    // Constructor
    Ball(float r_) {
      r = r_;
      x = random(width);
      y = random(height);
      xspeed = random(-5,5);
      yspeed = random(-5,5);
      }
    
    void move() {
      x += xspeed;          // Increment x
      y += yspeed;          // Increment y
      
      // Check horizontal edges
      if (x > width || x < 0) {
        xspeed *= -1;
        }
      // Check vertical edges
      if (y > height || y < 0) {
        yspeed *= -1;
        }
      }
      
     // Draw the ball
     void display() {
       stroke(255);
       fill(c);
       ellipse(x,y,r*2,r*2);
       c = color(255,50);
       }
       
     void highlight() {
       c = color(255,150);
       }
       
     // A function that returns true or false based on whether two circles intersect
     // If distance is less than the sum of radii the circles touch
   boolean intersect(Ball b) {
     float distance = dist(x,y,b.x,b.y);    // Calculate distance
     if (distance < r + b.r) {
       return true;
       }
       else {
         return false;
         }
     }  
    }