问题：键盘事件，首先被响应的是MainWindow这个主窗口类，经过一个下午的搜索方法，例如将焦点放在子窗口上，在这个子窗口类中使用keypressevent方法和updateGL方法，依然行不通，最后在QQ的几个专业群里进行求问，得到的答案：子窗口可以响应鼠标事件， 就是不能响应键盘事件，因此只有在MainWindow主窗口类中，用信号槽连接主窗口和子窗口，主窗口中使用keypressevent方法和定义一个信号，在这个方法中触发信号，传递变化的参数，子窗口中写槽事件，接受变化的参数，槽事件中用updateGL方法。

程序如下：

main.cpp: 

#include "opengl.h"

#include 

int main(int argc, char *argv[])

{

         QApplication a(argc, argv);

         QTextCodec *codec = QTextCodec::codecForName("System");   

         QTextCodec::setCodecForLocale(codec); 

         QTextCodec::setCodecForCStrings(codec); 

         QTextCodec::setCodecForTr(codec); 

         opengl *w=new opengl;

         w->show();

         return a.exec();

}

opengl.h:

#ifndef OPENGL_H

#define OPENGL_H

#include 

#include 

#include "NeHeWidget.h"

class opengl : public QMainWindow

{

         Q_OBJECT

public:

         opengl(QWidget *parent = 0, Qt::WFlags flags = 0);

         ~opengl();

private slots:

    void openCloud();

signals:

         void angleChanged(float,float);

protected:

         void keyPressEvent(QKeyEvent *e);

private:

         QMenu* menu;

         QAction* open;

         QMdiArea* mdiarea;

         QMenuBar* bar;

         NeHeWidget* cloudwidget;

         float rtri;

         float qtri;

};

#endif // OPENGL_H

opengl.cpp:

#include "opengl.h"

opengl::opengl(QWidget *parent, Qt::WFlags flags)

         : QMainWindow(parent, flags)

{

         menu=new QMenu(tr("云"),this);

         open=menu->addAction(QIcon(""),tr("打开"));

         bar=menuBar();

         bar->addMenu(menu);       

         connect(open,SIGNAL(triggered()),this,SLOT(openCloud()));        

         mdiarea=new QMdiArea;

         setCentralWidget(mdiarea);

         rtri=0.0;

         qtri=0.0;

}

opengl::~opengl()

{

}

void opengl::openCloud()

{

         cloudwidget=new NeHeWidget(0,0);

         connect(this,SIGNAL(angleChanged(float,float)),cloudwidget,SLOT(setAngle(float,float)));

         QMdiSubWindow* subwindow=mdiarea->addSubWindow(cloudwidget);

         subwindow->setWindowTitle("云场");

         subwindow->resize(800,400);

         subwindow->show();

}

void opengl::keyPressEvent(QKeyEvent *e)

{

         switch(e->key()) {

                 case Qt::Key_S:

                          rtri+=1.1;

                          qtri-=1.1;

                          emit angleChanged(rtri,qtri);

             default:

                     break;

                        }

} 

NeHeWidget.h: 

#ifndef NEHEWIDGET_H

#define NEHEWIDGET_H

#include  

class NeHeWidget: public QGLWidget

{

    Q_OBJECT

public:

    NeHeWidget( QWidget* parent = 0,const QString title = 0);

    ~NeHeWidget( void );

protected:

    void InitializeGL( void );

    void paintGL( void );

    void resizeGL( int width, int height ); 

protected:

         GLfloat rTri;

         GLfloat rQuad;

public slots:

         void setAngle(float rangle,float qangle);

};

#endif // NEHEWIDGET_H

NeHeWidget.cpp: 

#include 

#include 

#include "NeHeWidget.h"

NeHeWidget::NeHeWidget( QWidget* parent,

                        const QString title): QGLWidget(parent)

{

    setWindowTitle( title );

         rTri=0.0;

         rQuad=0.0;

}

NeHeWidget::~NeHeWidget(void)

{

}

void NeHeWidget::InitializeGL( void )

{

    glShadeModel( GL_SMOOTH );

    glClearColor( 1.0, 1.0, 0.0, 0.0 );

    glClearDepth( 1.0 );

    glEnable( GL_DEPTH_TEST );

    glDepthFunc( GL_LEQUAL );

    glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST );

}

void NeHeWidget::paintGL( void )

{

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    glLoadIdentity( );

    glTranslatef( -1.5f, 0.0f, -6.0f );

         glRotatef(rTri,0.0,1.0,0.0);

         glBegin( GL_TRIANGLES );

         glColor3f(1.0,0.0,0.0);

    glVertex3f( 0.0f, 1.0f, 0.0f );

         glColor3f(0.0,1.0,0.0);

    glVertex3f( -1.0f, -1.0f, 0.0f );

         glColor3f(0.0,0.0,1.0);   

         glVertex3f( 1.0f, -1.0f, 0.0f );

    glEnd( );

         glLoadIdentity();

         glTranslatef(1.5,0.0,-6.0);

         glRotatef(rQuad,1.0,0.0,0.0);

         glColor3f(0.5,0.5,1.0);

    glBegin( GL_QUADS );

    glVertex3f( -1.0f, 1.0f, 0.0f );

    glVertex3f( 1.0f, 1.0f, 0.0f );

    glVertex3f( 1.0f, -1.0f, 0.0f );

    glVertex3f( -1.0f, -1.0f, 0.0f );

    glEnd( );

}

void NeHeWidget::resizeGL( int width, int height )

{

    if ( height == 0 )

    {

        height = 1;

    }

    glViewport( 0, 0, (GLint)width, (GLint)height );

    glMatrixMode( GL_PROJECTION );

    glLoadIdentity( );

    gluPerspective( 45.0, (GLfloat)width / (GLfloat)height, 0.1, 100 );

    glMatrixMode( GL_MODELVIEW );

    glLoadIdentity( );

} 

void NeHeWidget::setAngle(float rangle,float qangle)

{

         rTri=rangle;

         rQuad=qangle;

         this->updateGL();

}