在学OpenGL时必须得东西。里面有使用说明，只有将glut的三个文件放在正确的位置，在编程时调用glut的函数时才会正确运行。初学者必须。-OpenGL in the study must have something. Inside there is the use of only three documents will be placed on the glut of right location, at the glut programming function calls when