OPENGL的入门第一个程序——Hello World

#include "stdafx.h"
#include<GL\glut.h>
void Init()
{
glClearColor(0.0f,0.0f,0.0f,0.0f);

}
void ChangeSize(int w,int h)
{
if (h==0)
{
h=1;
}
glViewport(0,0,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (w<=h)
{
gluOrtho2D(-100.0,100.0,-100.0*h/w,100.0*h/w);
}
else
{
gluOrtho2D(-100.0*w/h,100.0*w/h,1-100.0,100.0);
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void MyDisplay()
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(0.0,1.0,0.0);
glBegin(GL_POLYGON);
glVertex2f(-50.0f,-50.0f);
glVertex2f(50.0f,-50.0f);
glVertex2f(50.0f,50.0f);
glVertex2f(-50.0f,50.0f);
glEnd();
glutSwapBuffers();

}
int main(int argc,char ** argv)
{
glutInit(&argc,argv);

glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE);

glutInitWindowSize(500,500);
glutInitWindowPosition(500,100);
glutCreateWindow("Hello World");

Init();
glutDisplayFunc(MyDisplay);
glutReshapeFunc(ChangeSize);

glutMainLoop();

return 0;
}