_07_SimpleAnimation

int ballX = 240;
int ballY = 400;

int ballXspeed = 10;
int ballYspeed = 10;

void setup() {
  size( 480, 800 );
  background( 0 );
}

void draw() {
  background( 0 );
 
  moveTheBall();
}

//
void moveTheBall() {
  ballX = ballX + ballXspeed;
  ballY = ballY + ballYspeed;
 
  if( ballX < 5 ) {
    ballX = 5;
    ballXspeed = ballXspeed * -1;
  }
 
  if( ballX > 475 ) {
    ballX = 475;
    ballXspeed = ballXspeed * -1;
  }
 
  if( ballY < 5 ) {
    ballY = 5;
    ballYspeed = ballYspeed * -1;
  }
 
  if( ballY > 795 ) {
    ballY = 795;
    ballYspeed = ballYspeed * -1;
  }
 
  rect( ballX - 5, ballY - 5, 10, 10 );
}