GLUT甚至可以在应用程序过程中更改整个菜单.提供了两个函数: glutSetMenu和glutGetMenu.原型如下:

 

void glutSetMenu(int menu);

menu - 上一个创建菜单的索引值

该函数可以让我们切换菜单,例如在应用程序上下文中切换.

 

int glutGetMenu(void);

 

该函数返回当前菜单的索引值.下面我们演示用户按F1时在两个菜单之间切换.

void processSpecialKeys(int c, int x, int y) {    if (!flag) {        if (c == GLUT_KEY_F1) {            int x = glutGetMenu();            if (x == menu1)                glutSetMenu(menu2);            else                glutSetMenu(menu1);            // don't forget to attach the menu!!!            glutAttachMenu(GLUT_RIGHT_BUTTON);        }    }}void createGLUTMenus() {    menu2 = glutCreateMenu(processMenuEvents);    glutAddMenuEntry("Blue",BLUE);    glutAddMenuEntry("Green",GREEN);    glutAddMenuEntry("Red",RED);    menu1 = glutCreateMenu(processMenuEvents);    glutAddMenuEntry("Red",RED);    glutAddMenuEntry("Green",GREEN);    glutAddMenuEntry("Blue",BLUE);    glutAttachMenu(GLUT_RIGHT_BUTTON);}