NeHe 系列教程之四： 多边形旋转

英文教程地址：lesson04

本课在第三课的基础上增加了旋转多边形的代码，具体如下：

首先，在头文件中增加了两个旋转因子：

#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;GLfloat     rtri;                       // Angle For The Triangle ( NEW )GLfloat     rquad;                      // Angle For The Quad     ( NEW )
};#endif // MYGLWIDGET_H

在构造方法初始化旋转因子：

MyGLWidget::MyGLWidget(QWidget *parent) :QGLWidget(parent), fullscreen(false),rtri(0), rquad(0)
{setWindowTitle(tr("nehe----lesson04"));timer = new QTimer(this);connect(timer, SIGNAL(timeout()), this, SLOT(updateGL()));timer->start(10);
}

最后是实现旋转的部分：

void MyGLWidget::paintGL()
{glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);  // Clear The Screen And The Depth BufferglLoadIdentity();       // Reset The Current Modelview MatrixglTranslatef(-1.5f,0.0f,-6.0f);     // Move Left 1.5 Units And Into The Screen 6.0glPushMatrix();glRotatef(rtri, 0, 1.0f, 0);glBegin(GL_TRIANGLES);                      // Drawing Using TrianglesglColor3f(1.0f,0.0f,0.0f);           // Set The Color To RedglVertex3f( 0.0f, 1.0f, 0.0f);              // TopglColor3f(0.0f,1.0f,0.0f);          // Set The Color To GreenglVertex3f(-1.0f,-1.0f, 0.0f);              // Bottom LeftglColor3f(0.0f,0.0f,1.0f);          // Set The Color To BlueglVertex3f( 1.0f,-1.0f, 0.0f);              // Bottom RightglEnd();                            // Finished Drawing The TriangleglPopMatrix();glTranslatef(3.0f,0.0f,0.0f);                   // Move Right 3 UnitsglColor3f(0.5f,0.5f,1.0f);              // Set The Color To Blue One Time OnlyglRotatef(rquad, 1.0f, 0, 0);glBegin(GL_QUADS);                      // Draw A QuadglVertex3f(-1.0f, 1.0f, 0.0f);              // Top LeftglVertex3f( 1.0f, 1.0f, 0.0f);              // Top RightglVertex3f( 1.0f,-1.0f, 0.0f);              // Bottom RightglVertex3f(-1.0f,-1.0f, 0.0f);              // Bottom LeftglEnd();                         // Done Drawing The Quadrtri += 0.2f;                    // Increase The Rotation Variable For The Triangle ( NEW )rquad -= 0.15f;                  // Decrease The Rotation Variable For The Quad     ( NEW )
}

运行效果如下所示：