Circles with variable speed, size, and color

gistfile1.java

class MovingBall {
  float x, y, w, maxW, speed; // variables for drawing the ellipse
  boolean movingForward;
  boolean movingUp;
  boolean expanding;
  float r, g, b;
  
  void drawItself() {
    fill(r, g, b);
    ellipse(x, y, w, w);
  }
  
  void update() {
    if (expanding)
      w += 1;
    else
      w -= 1;
    
    if (movingForward)
      x += speed;
    else
      x -= speed;

    if (movingUp)
      y -= speed;
    else
      y += speed;
  }
  
  void check() {
    if (w <= 0)
      expanding = true;
      
    if (w >= maxW)
      expanding = false;
    
    if (y <= 0)
      movingUp = false;

    if (y >= height)
      movingUp = true;

    if (x >= width)
      movingForward = false;

    if (x <= 0)
      movingForward = true;
  }
}


MovingBall[] balls; // declaration
int numBalls;

void setup() {
  size(400, 400);
  smooth();
  frameRate(30);

  // setting up the space for 3 moving balls
  numBalls = 10;
  balls = new MovingBall[numBalls];

  // setting up the startup values for the balls in the array
  for (int i = 0; i < numBalls; i++) {
    balls[i] = new MovingBall();
    balls[i].x = random(0, width);
    balls[i].y = random(0, height);
    balls[i].w = random(5, 25);
    balls[i].maxW = balls[i].w;
    balls[i].speed = random(1, 5);
    balls[i].movingForward = true;
    balls[i].movingUp = true;
    balls[i].expanding = false;
    balls[i].r = random(0, 255);
    balls[i].g = random(0, 255);
    balls[i].b = random(0, 255);
  }


  fill(127);
  noStroke();
}

void draw() {
  background(255);
  fill(0);

  for (int i = 0; i < numBalls; i++) {
    balls[i].drawItself();
    balls[i].update();
    balls[i].check();
  }

}