void moveBall(){
  //Save current location of ball.
  tempX = x;
  tempY = y;

  switch(dir){
    case 0:
      //Direction is northwest.
      if((x <= radius) || (y <= radius)){
        dir = rand() % 4;;
      }else{
        //No collision, set 
        // new location for the ball
        --x;
        --y;
      }//end else
    break;