OpenGL中的变换：

平移：glTranslate3f(dx,dy,dz);
旋转：glRotate3f(angle, x, y, z);
缩放：glScale3f(sx, sy, sz);

练习内容：

1. 在窗口中绘制一个圆形和矩形。 ;
2. 再绘制一遍相同的圆和矩形，并作恰当的变换，使它们组合成一辆卡通汽车的形状。整个图形都显示在视图窗口内；

#include <windows.h>
#include <gl/glut.h>
#include "math.h"
int n = 3600;  //圆绘制次数
float PI = 3.1415926f;
float R = 0.8f;  //半径
void init(void) {glClearColor(1.0, 1.0, 1.0, 1.0);	glMatrixMode(GL_PROJECTION);	gluOrtho2D(-5.0, 5.0, -5.0, 5.0);  //设置显示的范围是X:-5.0~5.0, Y:-5.0~5.0	glMatrixMode(GL_MODELVIEW);    //设置当前操作的矩阵为“模型视图矩阵”
}void drawSquare(void)
{glBegin(GL_POLYGON);          //顶点指定需要按逆时针方向	glVertex2f(-1.0f,-1.0f);      //左下点	glVertex2f(1.0f,-1.0f);       //右下点	glVertex2f(1.0f,1.0f);        //右上点	glVertex2f(-1.0f,1.0f);       //左上点	glEnd();}
void drawCircle(void)
{//画圆glClearColor(0, 0, 0, 0);glColor4f(0, 0, 1, 0);glBegin(GL_POLYGON);for (int i = 0; i < n; i++){glVertex2f(R * cos(2 * PI * i / n), R * sin(2 * PI * i / n));   //定义顶点}glEnd();}void myDraw(void) {glClear(GL_COLOR_BUFFER_BIT);   glLoadIdentity();               glPushMatrix();                 glTranslatef(0.0f,0.0f,0.0f);   glScalef(2.0,0.8,1.0);         glColor3f(1.0,0.0,0.0);	drawSquare();                   glPopMatrix();  //下矩形glPushMatrix();                  glTranslatef(0.8f, 1.2f, 1.0f);   	glScalef(0.8, 0.4, 0.8);          	glColor3f(0.0, 1.0, 0.0);drawSquare();                  glPopMatrix();    //上矩形glPushMatrix();                 glTranslatef(-1.0f, -0.8f, 0.0f);   glScalef(0.6, 0.6, 1.0);          	glColor3f(0.0, 0.0, 1.0);drawCircle();               glPopMatrix();   //左圆glPushMatrix();                  	glTranslatef(1.0f, -0.8f, 0.0f);   	glScalef(0.6, 0.6, 1.0);          	glColor3f(0.0, 0.0, 1.0);drawCircle();                glPopMatrix();  //右圆glFlush();} 
void main(int argc, char** argv){	glutInit(&argc,argv);	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);	glutInitWindowPosition(0,0);	glutInitWindowSize(600,600);	glutCreateWindow("绘制小汽车"); init();	glutDisplayFunc(myDraw);	glutMainLoop();
}

练习结果截图：