_tnl_draw_prims: Assertion `ctx->NewState == 0x0'

OpenGL
1

Hi All

I’m trying to debug some code in GNU Octave where some OpenGL based plotting code causes a crash. I have been able to determine that the crash happens in a call to ‘glRasterPos3d’. Running things in ‘gdb’ gives me the following info:


fo#�X: tnl/t_draw.c:406: _tnl_draw_prims: Assertion `ctx->NewState == 0x0' failed.

Program received signal SIGABRT, Aborted.
0xb7fe1424 in __kernel_vsyscall ()
(gdb) bt
#0  0xb7fe1424 in __kernel_vsyscall ()
#1  0xb5102941 in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#2  0xb5105e42 in abort () at abort.c:92
#3  0xb50fb8e8 in __assert_fail (assertion=0xb1d342f4 "ctx->NewState == 0x0", file=0xb1d342e7 "tnl/t_draw.c", line=406, function=0xb1d3438c "_tnl_draw_prims") at assert.c:81
#4  0xb1bfd216 in ?? () from /usr/lib/dri/i965_dri.so
#5  0xb1b04148 in ?? () from /usr/lib/dri/i965_dri.so
#6  0xb1bf51f4 in ?? () from /usr/lib/dri/i965_dri.so
#7  0xb1bf0e17 in ?? () from /usr/lib/dri/i965_dri.so
#8  0xb1bf29f0 in ?? () from /usr/lib/dri/i965_dri.so
#9  0xb1baa0c1 in ?? () from /usr/lib/dri/i965_dri.so
#10 0xb757f8fc in glps_renderer::render_text (this=0xbfffb4a8, txt=..., x=0, y=1.0278551532033426, z=0, ha=1, va=2, rotation=0) at gl2ps-renderer.cc:144

Being a complete newbie in OpenGL I don’t really know how to debug this. Does anybody have any thoughts?

Thanks
Søren

2

Check that you already have a GL context initilized, before any other gl command.

Otherwise, it looks like you should file a bug to Mesa3D…

3

Thanks for the quick reply :slight_smile:

Admitting ignorance here, but how do I check that my context is initialised? I tried Google’ing this, but completely failed :frowning: In general, how do I find such information?

Thanks,
Søren

4

How do you create your opengl context ? Once it is done, it is initialized.

5

The thing is I’m trying to debug a rather large code base (GNU Octave) that I don’t know perfectly well. The code uses FLTK for windowing. I take your answer to mean that there is no function for determining if the current context exists. Is that correct? It would be excellent for me if I could simply add

std::cerr << is_gl_context_initialized () << std::endl;

to the code as it would allow me to easily determine if I should file a bug at Mesa3D or if I need to step through the code to determine why no context exists in the case that causes the crash. The thing is, I don’t know OpenGL well enough to determine if such a function exists or not.

Thanks

6

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