绘制3D图形，按鼠标切换其观察视角以达到旋转的目的。
  “我以前还会这个？我都惊了”，这是我大二做的，一年多以前的文章了。

#include <iostream>
#include <GL/glut.h>

/* -- - 常量-- - */
const int HEIGHT(800);
const int WIDTH(800);

void Display();
void Reshape(int w, int h);

int time(0);

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    //glut初始化

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
    //双缓存模式

    glutInitWindowSize(WIDTH, HEIGHT);
    glutInitWindowPosition(50, 100);
    //窗口初始化

    glClearColor(0, 0, 0, 1);
    //窗口颜色

    glutCreateWindow("Window - 3D");
    //窗口

    glutDisplayFunc(Display);
    glutReshapeFunc(Reshape);
    glutMainLoop();

    return 0;
}

void Display()
{
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    gluLookAt(4, 0, 1.5, 0, 0, 0, 1, 1, time++);

    time >= 3 ? time = -3:time;

    std::cout << "当前观察角度：(" << 1 << ", " << 1 << ", " << time << ")" << std::endl;

    //绘制正方体的面
    glColor3f(0, 1, 0);
    glBegin(GL_QUADS);
    //---1---
    glNormal3f(-1, 0, 0);//设置点的法向量
    glVertex3f(0.5, 0.5, 0.5);
    glVertex3f(0.5, -0.5, 0.5);
    glVertex3f(0.5, -0.5, -0.5);
    glVertex3f(0.5, 0.5, -0.5);
    //---2---
    glNormal3f(-1, 0, 0);
    glVertex3f(-0.5, 0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(-0.5, -0.5, -0.5);
    glVertex3f(-0.5, 0.5, -0.5);
    //---3---
    glNormal3f(0, 1, 0);
    glVertex3f(0.5, 0.5, 0.5);
    glVertex3f(-0.5, 0.5, 0.5);
    glVertex3f(-0.5, 0.5, -0.5);
    glVertex3f(0.5, 0.5, -0.5);
    //---4---
    glNormal3f(0, -1, 0);
    glVertex3f(0.5, -0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(-0.5, -0.5, -0.5);
    glVertex3f(0.5, -0.5, -0.5);
    //---5---
    glNormal3f(0, 0, 1);
    glVertex3f(0.5, 0.5, 0.5);
    glVertex3f(-0.5, 0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(0.5, -0.5, 0.5);
    //---6---
    glNormal3f(0, 0, -1);
    glVertex3f(0.5, 0.5, 0.5);
    glVertex3f(-0.5, 0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(0.5, -0.5, 0.5);
    glEnd();

    //draw
    glColor3f(0, 0, 0);
    glLineWidth(2.0f);
    //绘制正方体的边
    glBegin(GL_LINES);
    //---1---
    glVertex3f(0.5, 0.5, 0.5);
    glVertex3f(-0.5, 0.5, 0.5);
    glVertex3f(-0.5, 0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(0.5, -0.5, 0.5);
    glVertex3f(0.5, -0.5, 0.5);
    glVertex3f(0.5, 0.5, 0.5);
    //---2---
    glVertex3f(0.5, 0.5, -0.5);
    glVertex3f(-0.5, 0.5, -0.5);
    glVertex3f(-0.5, 0.5, -0.5);
    glVertex3f(-0.5, -0.5, -0.5);
    glVertex3f(-0.5, -0.5, -0.5);
    glVertex3f(0.5, -0.5, -0.5);
    glVertex3f(0.5, -0.5, -0.5);
    glVertex3f(0.5, 0.5, -0.5);
    //---3---
    glVertex3f(0.5, 0.5, 0.5);
    glVertex3f(0.5, -0.5, 0.5);
    glVertex3f(0.5, -0.5, 0.5);
    glVertex3f(0.5, -0.5, -0.5);
    glVertex3f(0.5, -0.5, -0.5);
    glVertex3f(0.5, 0.5, -0.5);
    glVertex3f(0.5, 0.5, -0.5);
    glVertex3f(0.5, 0.5, 0.5);
    //---4---
    glVertex3f(-0.5, 0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(-0.5, -0.5, 0.5);
    glVertex3f(-0.5, -0.5, -0.5);
    glVertex3f(-0.5, -0.5, -0.5);
    glVertex3f(-0.5, 0.5, -0.5);
    glVertex3f(-0.5, 0.5, -0.5);
    glVertex3f(-0.5, 0.5, 0.5);
    glEnd();

    //双缓存使用glutSwapBuffers，但缓存glFlush
    glutSwapBuffers();
}

void Reshape(int w, int h)
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glFrustum(-1.0, 1.0, -1.0, 1.0, 2.0, 10.0);
    glMatrixMode(GL_MODELVIEW);
}