glm::mat4 Camera::GetOrientation() const
{
    glm::mat4 mat(1);//identity matrix

    mat *= glm::rotate(glm::radians(_verticalAngle), glm::vec3(1, 0, 0));//rotate vertical (around the x axis)
    mat *= glm::rotate(glm::radians(_horizontalAngle), glm::vec3(0, 1, 0));//rotate horizontal (around the y axis)
    //no need to rotate around the z axis. Keep in mind that the rotation order is important in order to avoid gimbal lock.

    return mat;
}