这个文档介绍了glut的各种函数，包括初始化，窗口管理，事件处理，菜单管理，注册回调，色彩管理，状态检索，字体渲染，实体绘制以及各种实例的代码-This document describes the glut of various functions, including initialization, window management, event handling, menu management, register callback, color management, state re