static void timerCallback (int value) {
tetris.MoveDown();
/* call back again after elapsedUSecs have passed */
glutTimerFunc (tetris.msecs, timerCallback, value);
display();
}
void keyboard(unsigned char Key, int x, int y){
switch(Key){
case 'j':
tetris.MoveDown();
break;
case 'k':
tetris.MoveRotate();
break;
case 'h':
tetris.MoveLeft();
break;
case 'l':
tetris.MoveRight();
break;
default:
break;
};
display();
}