Kako da dobijem trenutno aktivnu rezoluciju - openGl?

Code:

int screenWidth = Glut.glutGet(Glut.GLUT_SCREEN_WIDTH);
int screenHeight = Glut.glutGet(Glut.GLUT_SCREEN_HEIGHT);
int windowWidth = Glut.glutGet(Glut.GLUT_INIT_WINDOW_WIDTH);
int windowHeight = Glut.glutGet(Glut.GLUT_INIT_WINDOW_HEIGHT);

Glut.glutInitWindowPosition(screenWidth/2-windowWidth/2, screenHeight/2-windowHeight/2);