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;
}