如何在Qt应用程序中替换'gluOrtho2d‘

#include <QOpenGLWidget>
#include <QOpenGLFunctions>

class MyOpenGLWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
    Q_OBJECT

public:
    MyOpenGLWidget(QWidget *parent = nullptr) : QOpenGLWidget(parent) {}

protected:
    void initializeGL() override
    {
        initializeOpenGLFunctions();
        // 在这里进行OpenGL的初始化操作
    }

    void paintGL() override
    {
        glClear(GL_COLOR_BUFFER_BIT);
        // 在这里进行OpenGL的绘制操作
    }
};

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2d(left, right, bottom, top);
glMatrixMode(GL_MODELVIEW);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(left, right, bottom, top, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    MyOpenGLWidget *glWidget = new MyOpenGLWidget(this);
    setCentralWidget(glWidget);
}