长方体的旋转问题

深山小竹

我在进行长方体的旋转时，在旋转的过程长方体发生了变形我的程序如下：请各位高手指点一下：
#include <GL/glut.h>
#define high 0.25
#define longth 2.5
#define wide 1.0
GLfloat angle=0;
void init(void)
{
  glClearColor(1.0,1.0,1.0,1.0);
  glShadeModel(GL_FLAT);
}
void colorcube()
{
        static GLfloat vd[]=
        {
                -wide,-longth,-high,
                wide,-longth,-high,
                wide,longth,-high,
                -wide,longth,-high,
                -wide,-longth,high,
                wide,-longth,high,
                -wide,longth,high,
                0.0,longth,high
        };
        static GLubyte fside[]={5,1,2,6};
    static GLubyte bside[]={4,7,3,0};
        static GLubyte rside[]={6,7,3,2};
        static GLubyte lside[]={4,5,1,0};
        static GLubyte aside[]={4,5,6,7};
        static GLubyte uside[]={0,3,2,1};
        glEnableClientState(GL_VERTEX_ARRAY);//开启顶点向量
    glVertexPointer(3,GL_FLOAT,0,vd);
    glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,fside);//前面
    glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,bside);//后面
    glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,rside);//右面
    glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,lside);//左面
    glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,aside);//上面
    glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,uside);//下面
}
void display(void)
{   
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);  //使用RGB颜色和深度缓存
    glLoadIdentity();
    gluLookAt(10.0,10.0,2.0,0,0,0,0.0,0.0,1.0);//设置视点，相机位于(-1.5,2.0,7.0),对准(0.0,0.0,0.0)
    glRotatef(angle,0,0,1);//旋转调试
    colorcube();//画下层立方体   
    glutSwapBuffers();
}
void reshape(int w,int h)
{
    glViewport(0.0,0.0,(GLfloat)w,(GLfloat)h);//定义视口大小
    glMatrixMode(GL_PROJECTION);//选择更改投影矩阵
    glLoadIdentity();//修改之前矩阵为单位矩阵
  //定义投影矩阵
    if(w<=h)
       glOrtho(-5.0,5.0,-5.0*(GLfloat)h/(GLfloat)w,5.0*(GLfloat)h/(GLfloat)w,-45.0,45.0);
    else
       glOrtho(-5.0*(GLfloat)h/(GLfloat)w,5.0*(GLfloat)h/(GLfloat)w,-5.0,5.0,-45.0,45.0);
    glMatrixMode(GL_MODELVIEW);//更改为模型视点矩阵
    glLoadIdentity();  
}
void keyboard(unsigned char key,int x,int y)
{
        switch(key){
        case 'q':
                angle+=5;
                if(angle>=360)
                        angle=0;
                glutPostRedisplay();
                break;
        case 'Q':
                angle-=5;               
                glutPostRedisplay();
                break;
        default:
                break;
        }
}
void main(int argc,char** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH|GLUT_MULTISAMPLE);
    glutInitWindowSize(500,500);
    glutInitWindowPosition(0,0);
    glutCreateWindow("cube");
    init();
    glutReshapeFunc(reshape);
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    glutMainLoop();
}