//Reverse Viewport transformation
    qreal conv_x = ( (mousex / (854.0/2.0)) -1);
    qreal conv_y = ( (mousey / (480.0/2.0)) -1);

    //Get viewport points as begin and end of the ray
    QVector4D nearPlane(conv_x, conv_y, -1, 0.0);
    QVector4D farPlane(conv_x, conv_y, +1, 0.0);

    //Multiply per the inverted ModelView matrix, to get world space coordinates of those points
    QVector4D nearPlane2 = cam_m.inverted() * nearPlane;
    QVector4D farPlane2 =   cam_m.inverted() * farPlane;

    nearPlane2.setX(nearPlane2.x() / nearPlane2.w());
    nearPlane2.setY(nearPlane2.y() / nearPlane2.w());
    nearPlane2.setZ(nearPlane2.z() / nearPlane2.w());

    farPlane2.setX(farPlane2.x() / farPlane2.w());
    farPlane2.setY(farPlane2.y() / farPlane2.w());
    farPlane2.setZ(farPlane2.z() / farPlane2.w());

    //direction, farPlane - nearPlane
    QVector4D direction = farPlane2 - nearPlane2;