int rectX, rectY;      // Position of square button
  int circleX, circleY;  // Position of circle button
  int rectSize = 50;     // Diameter of rect
  int circleSize = 53;   // Diameter of circle
  color rectColor, circleColor, baseColor;
  color rectHighlight, circleHighlight;
  color currentColor;
  boolean rectOver = false;
  boolean circleOver = false;
  
  void setup()
  {
    size(200, 200);
    smooth();
    rectColor = color(0);
    rectHighlight = color(51);
    circleColor = color(255);
    circleHighlight = color(204);
    baseColor = color(102);
    currentColor = baseColor;
    circleX = width/2+circleSize/2+10;
    circleY = height/2;
    rectX = width/2-rectSize-10;
    rectY = height/2-rectSize/2;
    ellipseMode(CENTER);
  }
  
  void draw()
  {
    update(mouseX, mouseY);
    background(currentColor);
    
    if(rectOver) {
      fill(rectHighlight);
    } else {
      fill(rectColor);
    }
    stroke(255);
    rect(rectX, rectY, rectSize, rectSize);
    
    if(circleOver) {
      fill(circleHighlight);
    } else {
      fill(circleColor);
    }
    stroke(0);
    ellipse(circleX, circleY, circleSize, circleSize);
  }
  
  void update(int x, int y)
  {
    if( overCircle(circleX, circleY, circleSize) ) {
      circleOver = true;
      rectOver = false;
    } else if ( overRect(rectX, rectY, rectSize, rectSize) ) {
      rectOver = true;
      circleOver = false;
    } else {
      circleOver = rectOver = false;
    }
  }
  
  void mousePressed()
  {
    if(circleOver) {
      currentColor = circleColor;
    }
    if(rectOver) {
      currentColor = rectColor;
    }
  }
  
  boolean overRect(int x, int y, int width, int height) 
  {
    if (mouseX >= x && mouseX <= x+width && 
        mouseY >= y && mouseY <= y+height) {
      return true;
    } else {
      return false;
    }
  }
  
  boolean overCircle(int x, int y, int diameter) 
  {
    float disX = x - mouseX;
    float disY = y - mouseY;
    if(sqrt(sq(disX) + sq(disY)) < diameter/2 ) {
      return true;
    } else {
      return false;
    }
  }