Chapter 4: Example 4-5: Using System Variables

// Learning Processing
// Daniel Shiffman
// http://www.learningprocessing.com

// Example 4-5: Using system variables
void setup() {
  size(200,200);
  smooth();
}

void draw() {
  background(100);
  stroke(255);
  // frameCount is used to color a rectangle.
  fill(frameCount / 2);
  rectMode(CENTER);
  // The rectangle will always be in the middle of the window 
  // if it is located at (width/2, height/2).
  rect(width/2,height/2,mouseX+10,mouseY+10);
}

void keyPressed() {
  println(key);
}