Donno

#include <GL/glut.h>const char * windowTitle = "OpenGL App 1";void Display(){    glClear(GL_COLOR_BUFFER_BIT);    /* Drow a nice Pentagon?*/    glBegin(GL_POLYGON);    glColor3f(0.0f,1.0f,0.0f);    glVertex2f( 0.0f, 0.5f);     glVertex2f(-0.4f, 0.1f);     glVertex2f(-0.2f,-0.5f);     glVertex2f( 0.2f,-0.5f);     glVertex2f( 0.4f, 0.1f);    glEnd();        glFlush();};int main(int argc, char** argv){    glutInit(&argc, &argv);    glutInitWindowSize( 720,  576);    //glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );    glutCreateWindow(windowTitle);    glutDisplayFunc(Display);    glutMainLoop();};