void onMouseEvent(int button, int state, int x, int y) {
    //important to convert the coordinates from window coordinates to world coordinates
    int width = glutGet(GLUT_WINDOW_WIDTH);
    int height = glutGet(GLUT_WINDOW_HEIGHT);
    Vector3 last_point;
    last_point.x = x - width / 2;
    last_point.y = height - y - (height / 2);

    if (button == GLUT_LEFT_BUTTON) {
        if (state == GLUT_DOWN) {

            pressed_points.push_back(last_point);

            if (pressed_points.size() < 5)
                last_point.z = randomizar() * 200;
            spline.addPoint(last_point);

            if (pressed_points.size() == 4)
                //per a la proxima practica s'implementarà una altra cosa diferent
                pintar = true;

        } else if (button == GLUT_RIGHT_BUTTON) {

            if (state == GLUT_DOWN) {
                std::cout << "hey" << std::endl;
                //find closer pressed point to the mouse pos and changes its pos to the new pos
                int id_closer = -1;

                float min_distance = 100000; //max value possible
                for (unsigned int i = 0; i < pressed_points.size(); ++i)
                    if (pressed_points[i].distance(last_point) < min_distance) {
                        id_closer = i;
                        min_distance = pressed_points[i].distance(last_point);

                    }
                if (id_closer != -1)
                    pressed_points[id_closer] = last_point;
                if (id_closer < 4) {
                    spline.splinePoints[id_closer] = last_point;
                }
            }
        }
    }
}