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//! [0]
    class MyGLWidget : public QGLWidget, protected QGLFunctions
    {
        Q_OBJECT
    public:
        MyGLWidget(QWidget *parent = 0) : QGLWidget(parent) {}

    protected:
        void initializeGL();
        void paintGL();
    };

    void MyGLWidget::initializeGL()
    {
        initializeGLFunctions();
    }
//! [0]

//! [1]
    void MyGLWidget::paintGL()
    {
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, textureId);
        ...
    }
//! [1]

//! [2]
    QGLFunctions glFuncs(QGLContext::currentContext());
    glFuncs.glActiveTexture(GL_TEXTURE1);
//! [2]

//! [3]
    QGLFunctions funcs(QGLContext::currentContext());
    bool npot = funcs.hasOpenGLFeature(QGLFunctions::NPOTTextures);
//! [3]