Keep Window Open

Question

Running C++, OpenGL and graphics output with Visual Studio.

Running OpenGL with a graphics window, when I execute, the window immediately closes at the program end before I can see what is happening. How does one keep the window open that has been created until ready to close, Sid Kraft

Answer 1

Hello @Sid Kraft ,

In a standard OpenGL application using GLUT (or FreeGLUT), you need to enter the GLUT event processing loop to keep the window open and responsive. You do this by calling glutMainLoop() at the end of your main function.

This function tells GLUT to start processing window events like drawing, resizing, and user input. It essentially runs an infinite loop that keeps your application alive until the window is closed by the user.

Here is a minimal example of how your main function should be structured, I have tested this and it should work fine:

#include <GL/glut.h>

void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    // ... your drawing code here ...
    glFlush();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("My OpenGL Window");

    // Register callbacks
    glutDisplayFunc(display);

    // Enter the infinite event-processing loop
    glutMainLoop(); 

    return 0; // The program will typically not reach here in classic GLUT
}

If you ever need the program execution to continue after the main loop (which classic GLUT does not support since glutMainLoop never returns), you might want to look into FreeGLUT (a modern substitute for GLUT), which provides glutMainLoopEvent() and glutLeaveMainLoop() for more control over the window lifecycle.

Additionally, if you are seeing a black console window (command prompt) close very quickly when running in Visual Studio (and not the graphics window itself), you can prevent it from closing by pressing Ctrl + F5 (Start Without Debugging) instead of F5, or by putting system("pause"); just before your return 0;. However, for the OpenGL graphics window itself, glutMainLoop() is the correct approach.

Hopefully, this solves your issue.

If you found my response helpful or informative, I would greatly appreciate it if you could follow this guidance or provide feedback.

Thank you. 

Answer 2

Need to re-phrase, using the glutInit function in OpenGL, C++, Sid Kraft

Answer 3

Keep the app alive by running the Windows message loop until the window is closed. In a Windows desktop app, the program stays in its while loop until the user closes the window and exits the application.

For closing behavior:

• When the user clicks Close or presses Alt+F4, the window receives WM_CLOSE.
• If WM_CLOSE is not handled, DefWindowProc destroys the window by default.
• When the window is being destroyed, it receives WM_DESTROY.
• In the main window, handle WM_DESTROY by calling PostQuitMessage(0), which posts WM_QUIT and ends the message loop.

Typical pattern:

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR, int nCmdShow)
{
    // register class, create window, show window...

    MSG msg = {};
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}

If confirmation is needed before closing, handle WM_CLOSE and call DestroyWindow(hwnd) only when ready:

case WM_CLOSE:
    if (MessageBox(hwnd, L"Really quit?", L"My application", MB_OKCANCEL) == IDOK)
    {
        DestroyWindow(hwnd);
    }
    return 0;

For an OpenGL window specifically, create the rendering context during window creation and release it when the window is closed, after making the rendering context not current.

---

• Closing the Window
• Module 1. Your First Windows Program
• Creating a Rendering Context and Making It Current
• Deleting a Rendering Context