Re: [wx-dev] [patch] glx11.cpp(51) assert "fbc" failed

[Vadim Zeitlin]

On Fri, 5 Oct 2012 02:05:09 -0700 (PDT) mvogt1 wrote:

m> when using wxWidgets 2.9.4 with the open GL example from:
m>
m> http://wiki.wxwidgets.org/WxGLCanvas#wxGLCanvas_sample

Do the OpenGL samples included in wxWidgets, e.g. samples/opengl/cube,
fail for you as well? I expect they do but just to be sure.

m> This error only occurs in the indirect rendering case, where the X11 server
m> runs nvidia 295.71 and the remote/local libGL is Mesa-7.3-3.2
m> (Suse Linux Enterprise 11)
m> I have not tested other Mesa implementations.

I don't have the possibility to test this case unfortunately...

m> So I came up with this first test ("patch")
m>
m> *pFBC = glXChooseFBConfig(dpy, DefaultScreen(dpy), data, &returned);
m> if ( *pFBC == NULL) {
m> printf("No Framebuffer. Fallback to NULL as last resort\n");
m> *pFBC = glXChooseFBConfig(dpy, DefaultScreen(dpy), NULL, &returned);
m> }
m>
m> This completely ignores the given attributes, but works in my
m> case.

I have trouble believing that this would be the right thing to do...
Completely ignoring the attributes just doesn't seem to be right. And
passing NULL is different from ignoring the attributes too, see
http://www.opengl.org/sdk/docs/man/xhtml/glXChooseFBConfig.xml

I don't know much about OpenGL and in particular don't know what is
special about this "indirect rendering case" but I still think there must
be some way to specify the attributes even then. If you can find more about
it, please let us know.

Thanks and good luck,
VZ