NeHe教程Qt实现——lesson01

NeHe 系列教程之一： 创建一个OpenGL 窗口

英文教程地址：　lesson01

在Qt的实现中， 我们主要依赖QGLWidget类， 我们主要重载三个重要方法 ：

    void initializeGL();
    void resizeGL(int w, int h);
    void paintGL();

下面给出实现代码，本课代码框架也是后续课程代码的基础，一些通用代码仅在此课中展示。

首先，声明创建OpenGL窗口类，它继承于QGLWidget， 代码如下：

#ifndef MYGLWIDGET_H
#define MYGLWIDGET_H

#include <QGLWidget>

class QTimer;
class QKeyEvent;

class MyGLWidget : public QGLWidget
{
    Q_OBJECT
public:
    explicit MyGLWidget(QWidget *parent = 0);

protected:
    void initializeGL();
    void resizeGL(int w, int h);
    void paintGL();

    void keyPressEvent(QKeyEvent *);
    void closeEvent(QCloseEvent *);

private:
    QTimer *timer;

    bool fullscreen;  //窗口是否全屏显示
};

#endif // MYGLWIDGET_H

该类主要声明了三个重载方法，并重载了按键和关闭窗口事件响应方法。

窗口类的实现代码如下：

#include "myglwidget.h"
#include <QTimer>
#include <QKeyEvent>
#include <QMessageBox>
#include <QApplication>
#include <QDebug>

MyGLWidget::MyGLWidget(QWidget *parent) :
    QGLWidget(parent), fullscreen(false)
{
    setWindowTitle(tr("nehe----lesson01"));
    timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(updateGL())); //不停刷新窗口
    timer->start(10);
}

void MyGLWidget::initializeGL()
{
    glShadeModel(GL_SMOOTH);   // Enables Smooth Shading
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);  // Black Background
    glClearDepth(1.0f);             // Depth Buffer Setup
    glEnable(GL_DEPTH_TEST);        // Enables Depth Testing
    glDepthFunc(GL_LEQUAL);        // The Type Of Depth Test To Do
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
}

void MyGLWidget::resizeGL(int width, int height)
{
    if (height==0) {    // Prevent A Divide By Zero By
        height=1;    // Making Height Equal One
    }
    glViewport(0, 0, width, height);    // Reset The Current Viewport
    glMatrixMode(GL_PROJECTION);       // Select The Projection Matrix
    glLoadIdentity();                  // Reset The Projection Matrix

    // Calculate The Aspect Ratio Of The Window
    gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

    glMatrixMode(GL_MODELVIEW);      // Select The Modelview Matrix
    glLoadIdentity();                // Reset The Modelview Matrix
}

void MyGLWidget::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);  // Clear The Screen And The Depth Buffer
    glLoadIdentity();       // Reset The Current Modelview Matrix
    qDebug("NeHe--Lesson1");
}

void MyGLWidget::keyPressEvent(QKeyEvent *e)
{
    switch (e->key()) {
    case Qt::Key_F:  //F 键进行全屏切换
        fullscreen = !fullscreen;
        if (fullscreen) {
            showFullScreen();
        } else {
            resize(640, 480);
            showNormal();
        }
        break;
    case Qt::Key_Escape:   //退出确认
        QMessageBox::StandardButton reply;
        reply = QMessageBox::question(NULL, "NeHe",
                           "Do you want to exit?",
                           QMessageBox::Yes | QMessageBox::No,
                           QMessageBox::Yes);
        if (reply == QMessageBox::Yes) {
                qApp->quit();
        }
        break;
    default:
        QGLWidget::keyPressEvent(e);
        break;
    }
}
//点击窗口关闭按键时确认退出
void MyGLWidget::closeEvent(QCloseEvent *e)
{
    QMessageBox::StandardButton reply;
    reply = QMessageBox::question(this, "NeHe",
                       "Do you want to exit?",
                       QMessageBox::Yes | QMessageBox::No,
                       QMessageBox::No);
    if (reply == QMessageBox::Yes) {
            e->accept();
    } else {
        e->ignore();
    }
}

main函数中的代码如下所示：

#include <QApplication>
#include "myglwidget.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MyGLWidget win;
    win.show();

    return app.exec();
}

运行效果如下所示：