使用过剩重启蛇游戏

Question

I wrote a c++ snake game using OpenGL and GLUT. The problem is that I implemented a small menu, with 2 buttons: new game, exit. I'm having a hard time with the "new game" part. I've been moving here and there lines of code and I don't know how it should be. Main looks like this:

int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(800, 600);
glutInitWindowPosition(100, 100);
glutCreateWindow("Aarghhh! O ramaaa !");
createMenu();      
glClearColor(0.0, 0.0, 0.0, 0.0);
glutIdleFunc(display_menu);
init();
glutReshapeFunc(reshape);
glutDisplayFunc(dreptunghi);
glutSpecialFunc(player);
glutMainLoop();
return 0;
}

where init, createMenu and display_menu look like this:

 void init(void) {
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0.0, 800.0, 0.0, 600.0);
    glShadeModel(GL_FLAT);
 }

 void menu(int num) {
    if (num == 0)
        exit(0);
    else {
        if (num == 1) {
            menu_value = num;           
        }
    }

    //glutPostRedisplay();
 }

 void createMenu(void) {
    glutCreateMenu(menu);
    glutAddMenuEntry("New game!", 1);
    glutAddMenuEntry("Exit", 0);    
    glutAttachMenu(GLUT_RIGHT_BUTTON);
 }

 void display_menu(void){
    if (menu_value == 1) {
        snake.clear();
        i = 30.0;
        j = 30.0;
        alpha = 1.0;
        value = -1;
        speed = 3;
        eaten = true;
        collided_food = false;
        collided_self = false;

        createMenu();
        glClearColor(0.0, 0.0, 0.0, 0.0);
        glutIdleFunc(display_menu);

        init();
        glutDisplayFunc(dreptunghi);
        glutReshapeFunc(reshape);
        glutSpecialFunc(player);
        //glutMainLoop();
    }
    glutSwapBuffers();
 }

The thing is: if I place the content of display_menu inside the if statement from menu function, it works, but I have to resize the window for the redrawing to happen (I realised that this happens because MainLoop expects an event, but I have no idea how to beat this). If I keep it this way, it doesn't change anything to good, only to worse. I'm new to this and I'm having troubles finding out how this works.

Answer 1

If anybody has the same problem, this is how I solved it:

void menu(int num) {
if (num == 0) {
    if (engine)
        engine->drop();
    exit(0);
}
else {
    if (num == 1) {
        menu_value = num;   
        snake.clear();
        i = 30.0;
        j = 30.0;
        nou.set(i, j);
        snake.push_back(nou);
        alpha = 1.0;
        value = -1;
        speed = 3;
        eaten = true;
        collided_food = false;
        collided_self = false;

        createMenu();
        glClearColor(0.0, 0.0, 0.0, 0.0);

        glClearColor(1.0, 1.0, 1.0, 0.0);
        glutDisplayFunc(dreptunghi);
        glutReshapeFunc(reshape);
        glutSpecialFunc(player);
    }
}
glutSwapBuffers();
glutPostRedisplay();
}

while the init() function remains intact.