Hi, I'm new to Processing, so sorry if this question is insanely easy. I'm making a ball move only left and right, but I want to follow it as it moves past halfway of the screen. Then I'll be able to see the numbers that follow. Eventually, I want to follow it as it moves up and down past the display screen's y axis halfway point. How would I do this? I heard that you're supposed to use translate and push/pop matrixes, but I can't wrap my head around it. Thanks!

Code:

PFont f;
int xpos, ypos;

void setup() {
  f = loadFont("Algerian-48.vlw");
  textFont(f, 48);
  size(800, 600);
}

void draw() {
  background(204);
  fill(0);
  text(1, 500, 300);
  text(2, 1000, 300);
  text(3, 1500, 300);
  text(4, 2000, 300);
  text(5, 2500, 300);
  ellipse(xpos, ypos, 100, 100);
}


void keyPressed() {
  if (key == 'd' || key == 'D')
    xpos = xpos + 5;
  if (key == 'a' || key == 'A')
    xpos = xpos - 5;
}