Draw a Filled Polygon : OpenGL / Graph Programme

#include <windows.h>
#include <stdio.h>
#include <conio.h>
#include <iostream.h>
#include <stdlib.h>
#include <glut.h>

void myInit(void)
{
    glClearColor(1.0,1.0,1.0,0.0);
    glColor3f(1.0f,0.0f,0.0f);
    glPointSize(4.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.0,800.0,0.0,600.0);
}

void myDisplay(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_POLYGON);
    glVertex2i(100,100);
    glVertex2i(100,300);
    glVertex2i(400,300);
    glVertex2i(600,150);
    glVertex2i(400,100);
    glEnd();
    glFlush();
}
int main(int argc,char * argv[])
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
    glutInitWindowSize(800,600);
    glutInitWindowPosition(100,100);
    glutCreateWindow("opengl Window");
    glutDisplayFunc(myDisplay);
    myInit();
    glutMainLoop();
    getch();
    return 0;
}