float ball1_posX;
float ball1_posY;
float ball1_speedX;
float ball1_speedY;
float ball2_posX;
float ball2_posY;
float ball2_speedX;
float ball2_speedY;
float ball3_posX;
float ball3_posY;
float ball3_speedX;
float ball3_speedY;

void setup() {
  size( 400, 300 );
  ball1_posX = random(width);
  ball1_posY = random(height);
  ball1_speedX = random(-5, 5);
  ball1_speedY = random(-5, 5);

  ball2_posX = random(width);
  ball2_posY = random(height);
  ball2_speedX = random(-5, 5);
  ball2_speedY = random(-5, 5);

  ball3_posX = random(width);
  ball3_posY = random(height);
  ball3_speedX = random(-5, 5);
  ball3_speedY = random(-5, 5);

  fill( 255, 0, 0 );
}

void draw() {
  background( 255 );
  ball1_posX += ball1_speedX;
  ball1_posY += ball1_speedY;

  ball2_posX += ball2_speedX;
  ball2_posY += ball2_speedY;

  ball3_posX += ball3_speedX;
  ball3_posY += ball3_speedY;

  if ( ball1_posX > width-15 ) {
    ball1_posX = width-15;
    ball1_speedX = -ball1_speedX;
  }
  if ( ball1_posX < 15 ) {
    ball1_posX = 15;
    ball1_speedX = -ball1_speedX;
  }
  if ( ball1_posY > height-15 ) {
    ball1_posY = height-15;
    ball1_speedY = -ball1_speedY;
  }
  if ( ball1_posY < 15 ) {
    ball1_posY = 15;
    ball1_speedY = -ball1_speedY;
  }

  if ( ball2_posX > width-15 ) {
    ball2_posX = width-15;
    ball2_speedX = -ball2_speedX;
  }
  if ( ball2_posX < 15 ) {
    ball2_posX = 15;
    ball2_speedX = -ball2_speedX;
  }
  if ( ball2_posY > height-15 ) {
    ball2_posY = height-15;
    ball2_speedY = -ball2_speedY;
  }
  if ( ball2_posY < 15 ) {
    ball2_posY = 15;
    ball2_speedY = -ball2_speedY;
  }

  if ( ball3_posX > width-15 ) {
    ball3_posX = width-15;
    ball3_speedX = -ball3_speedX;
  }
  if ( ball3_posX < 15 ) {
    ball3_posX = 15;
    ball3_speedX = -ball3_speedX;
  }
  if ( ball3_posY > height-15 ) {
    ball3_posY = height-15;
    ball3_speedY = -ball3_speedY;
  }
  if ( ball3_posY < 15 ) {
    ball3_posY = 15;
    ball3_speedY = -ball3_speedY;
  }

  ellipse(ball1_posX, ball1_posY, 30, 30);
  ellipse(ball2_posX, ball2_posY, 30, 30);
  ellipse(ball3_posX, ball3_posY, 30, 30);
}