// Learning Processing
  // Daniel Shiffman
  // http://www.learningprocessing.com
  
  // Example 14-5: Rectangle rotating around center
  
  void setup() {
    size(200,200);
  }
  
  void draw() {
    background(255);
    stroke(0);
    fill(175);
    
    // Translate origin to center
    translate(width/2,height/2);
    
    // The greek letter, theta, is often used as the name of a variable to store an angle
    // The angle ranges from 0 to PI, based on the ratio of mouseX location to the sketch's width.
    float theta = PI*mouseX / width; 
    
    // Rotate by the angle theta
    rotate(theta);
    
    // Display rectangle with CENTER mode
    rectMode(CENTER);
    rect(0,0,100,100);
  }