void MyOpenGLWidget::loadTexture()
{
    if (eof == true)
        return;
    img_data = SOIL_load_image(path, &width, &height, &channels, SOIL_LOAD_RGB);
    glEnable(GL_TEXTURE_2D);
    glGenTextures(1, &texture); // exception thrown here
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, img_data);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    SOIL_free_image_data(img_data);
}

void MyOpenGLWidget::initializeGL()
{
    initializeOpenGLFunctions();
    // some other code here
}

class MyGLThread : public QThread
{
    Q_OBJECT

public:
    MyGLThread();
    ~MyGLThread();

    void init(MyOpenGLWidget* widget);
    void loadTexture();

    // some other code here

protected:
    virtual void run();

private:
    MyOpenGLWidget* gl_widget;
};

MyGLThread::MyGLThread()
{
    gl_widget = nullptr;
}

MyGLThread::~MyGLThread()
{
}

void MyGLThread::init(MyOpenGLWidget * widget)
{
    gl_widget = widget;
}

void GLThread::loadTexture()
{
    gl_widget->loadTexture();
}

void MyGLThread::run()
{
    while (true) {
        if (!gl_widget)
            continue;

        loadTexture();
        msleep(30);
    }
}

INSlides::INSlides(QWidget *parent)
    : QMainWindow(parent)
{
    ui.setupUi(this);

    extractor_thread = new ExtractorThread(); // thread used to extract images
    extractor_thread->start();

    gl_widget = new MyOpenGLWidget(this);
    gl_widget->setGeometry(100, 100, 1280, 720);

    gl_thread = new MyGLThread();
    gl_thread->init(gl_widget);
    gl_thread->start();

    connect(ui.openFileAction, SIGNAL(triggered()), this, SLOT(openFile()));
}