OpenGL绘制一个点、线、多边形

#include "stdafx.h"
#include  
#include 
// #include 
// #include 
#include 
const int n = 20;
const GLfloat R = 0.5f;
const GLfloat Pi = 3.1415926536f;
void MyDisplay(void)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();//该函数的功能是重置当前指定的矩阵为单位矩阵.

	//绘制点
	glPointSize(5.0);//点的像素大小，默认值为1.0
	glBegin(GL_POINTS);               
	glVertex2f(0.0f, 0.0f);
	glVertex2f(0.5f, 0.5f);
	glEnd();

	//绘制直线
	glLineWidth(2.0f);//直线的宽度。
	glEnable(GL_LINE_STIPPLE);//绘制虚线
	glLineStipple(2, 0x0F0F);
	glBegin(GL_LINES); //绘制实线
	glVertex2f(0.5f, 0.6f);
	glVertex2f(0.6f, 0.9f);
	glEnd();

	//绘制多边形
	glColor3f(255.0,0.0,0.0);
	glBegin(GL_POLYGON);
	//glBegin(GL_LINE_LOOP);
	//glBegin(GL_POINTS);
	for(int i=0; i