float x,y;
int x_direction;
int y_direction;
float x_speed;
float y_speed;

void setup(){
  size(300,300);
  x_direction=1;
  y_direction=1;
  x_speed=1.2;
  y_speed=1;

}
void loop(){
  background(255,255,255);

  x=x+(x_speed*x_direction);
  y=y+(y_speed*y_direction);

  ellipse(x,y,20,20);

  if(x > 300 || x < 0){
    x_direction *=-1;
  }

  if(y > 300 || y < 0){
    y_direction *=-1;
  }

  x=x+x_direction;
  y=y+y_direction;

}