采用GLUT库，实现了一个彩色三角形在窗口内匀速转动（按下键盘上“ESC”键退出），请修改代码，实现窗口中三角形右边画一个正方形，并让该正方形也能匀速转动。-Using GLUT library that implements a colored triangle in the window uniform rotation (the keyboard by pressing " ESC"　key to exit), modify the code to achieve the right side of the window to draw a square triangle, and let the square can also be uniform rotation.