// Dartmouth CS 2, Winter 2009, Chris Bailey-Kellogg
// Notes 7 | Sketch 2

// The current coordinates of the ball
float x, y;
// Step sizes
float dx=1, dy=1;

void setup()
{
  size(400,400);
  smooth();
  background(0);
  fill(255);
  noStroke();

  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;
}

void draw()
{
  background(0);
  ellipse(x,y,20,20);

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

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