OpenGL /GLUT Creating window after mainEventLoop()

Question

I am developing a game in OpenGL/GLUT and I need to open a new window to show the score when the game is won.

In order to do this, i will call glutCreateWindow() and register the callbacks after calling mainEventLoop().

Is there a problem with this ? How should I do it properly ?

Answer 1

Is there a problem with this?

Yes.

Why don't you simply draw the results in the same window as the game?

Why are you using GLUT in the first place? It's not a very good framework for games. Better use GLFW or SDL.

How should I do it properly ?

By adding a small GUI system to your engine, that allows you to overlay the screen with stats (like a HUD) and a score screen.

Answer 2

You will need two display callback functions, display( ) and display2( ) for each window plus window = glutCreateWindow("Window 1"); and window2 = glutCreateWindow("Window 2");.

Code example :

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <GL/glut.h>

int window2 = 0, window = 0, width = 400, height = 400;

void display(void)
{
    glClearColor(0.0, 1.0, 1.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    printf("display1\n");
    glFlush();
}

void display2(void)
{
    glClearColor(1.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    printf("display2\n");
    glFlush();
}

void reshape (int w, int h)
{
    glViewport(0,0,(GLsizei)w,(GLsizei)h);
    glutPostRedisplay();
}

int main(int argc, char **argv)
{
    // Initialization stuff
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB);
    glutInitWindowSize(width, height);

    // Create  window main
    window = glutCreateWindow("Window 1");
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutInitWindowPosition(100,100);

    // Create second window
    window2 = glutCreateWindow("Window 2");
    glutDisplayFunc(display2);
    glutReshapeFunc(reshape);

    // Enter Glut Main Loop and wait for events
    glutMainLoop();
return 0;
}