Re: Recent X11 upgrade and getting _gl?? Undefined references compiling another package

[André Bleau <andre_bleau at hotmail dot com>]

Brian Keener  wrote:
 
> OSG completes its build now with the new libglut32.a.  
 
Excellent.
 
> It builds an example 
> program osgviewerGLUT.exe which opens a window and diplays an image.  When I 
> click the close box on that window I get a segmentation fault when the app 
> closes.  The app will also close when you simply press the escape key.  This 
> leaves the process running in the background as if I had used the hack  
> -DGLUT_DISABLE_ATEXIT_HACK.
> When I used the escape I had to kill the process manually.  Not sure if this is 
> a glut issue or an issue with their example window but thought I would let you 
> know.
> bk
 
Hi Brian,
 
I took a look at osgviewerGLUT. Did that ever worked well with some previous version
of the opengl package? I see a few strange things:
 
void keyboard( unsigned char key, int /*x*/, int /*y*/ )
{
    switch( key )
    {
        case 27:
            // clean up the viewer 
            if (viewer.valid()) viewer = 0;
            glutDestroyWindow(glutGetWindow());
            break;
//...
    }
}

Typing esc only destroys the window without stoping the program, which continue with a
dangling viewer pointer; no wonder that you have to kill it manually. 
Instead of calling glutDestroyWindow(glutGetWindow()); it should call exit(0); , maybe after
calling delete viewer; .
 
void display(void)
{
    // update and render the scene graph
    if (viewer.valid()) viewer->frame();
    // Swap Buffers
    glutSwapBuffers();
    glutPostRedisplay();
}
 
glutPostRedisplay(); will have display() called again, so it creates an infinite loop.
It should not be there. glutPostRedisplay(); should rather be at the end of 
mousebutton, mousemove, and keyboard.

Closing the window with the (X) icon should result in simply calling exit(0) and destroying the 
window. As to why it segfaults, you would have to degug it, as I don't have
OpenSceneGraph installed.
 
Regards,
 
- André Bleau, Cygwin's volunteer OpenGL package maintainer.
 
Please direct any question or comment about the OpenGL package to cygwin at cygwin dot com
 
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