float x, y; // The current coordinates of the ball
float r = 20; // ball radius
float vx=1, vy=1; // ball velocity

void setup()
{
  size(400,400);
  smooth();
  noStroke();

  // print instructions
  println("x/X: de/increase x step size");
  println("y/Y: de/increase y step size");
  println("c: go to center of window");
  
  x = width/2; y = height/2; // start at the center
}

void draw()
{
  background(0);
  ellipse(x,y,2*r,2*r);

  // take a step
  x += vx; y += vy;
  // stay on screen
  x = constrain(x,0,width);
  y = constrain(y,0,height);
}

void keyPressed()
{
  if (key=='x') vx--;
  else if (key=='X') vx++;
  else if (key=='y') vy--;
  else if (key=='Y') vy++;
  else if (key=='c') {
    x = width/2;
    y = height/2;
  }
  println("velocity: "+vx+","+vy);
}

// START NO NOTES
// code used to capture screenshots
void keyReleased() {
  if(key == '`' && !online) save("sketch.png");
}