glutInit(&rgc, argv);
Initialize GLUT
glutCreateWindow(“Vertex, Primitive & Color”);
Create Window with given title
glutInitWindowSize(320, 320);
Set the window’s initial width & height
glutWindowPosition(50, 50);
Position the window’s initial top-left corner
glutDisplayFunc(display);
Register callback handler for window re-paint event
initGL();
Our own OpenGL initialization
glutMainLoop();
Enter the event-processing loop
gluOrtho2D
Set the clipping area of 2D orthographic view
glViewport
configure the viewport