Re: [PyOpenGL-Devel] Possible bug in PyOpenGL wrapper of glGenTextures?

[Mike C. F. <mcf...@vr...>]

On 09/08/2014 03:48 AM, Karl Koscher wrote:
> I'm running GNU Radio on Windows and was trying to figure out why the 
> WX FFT display wasn't working. It looks like glGenTextures(1) is the 
> culprit. An argument of 1 is special-cased for 
> backwards-compatibility, but this seems to break. Commenting this 
> special case out fixes the FFT display.
>
> I think the problem is that a single ulong is passed in to the 
> underlying function, but it always expects an array of ulongs. I think 
> an array should still be passed in, with the first element of the 
> array returned in the special case (instead of the array itself).
>
> Of course, this is all voodoo magic to me, so perhaps there's a good 
> reason for the code the way it is. It would be nice for it to work on 
> Windows without hacking the code, though.

In ctypes, passing in a <ulong> variable acts as a single-element 
*ulong, so that *shouldn't* be the issue. However, it is always possible 
that we've got a bug in the handling. Thing is, I can't see anything 
wrong with the gnuradio code, and without a traceback or other error to 
tell me *what* went wrong, I can't investigate further.  I'm assuming 
that gnuradio would require a piece of hardware to run, which suggests I 
wouldn't be able to reproduce the error easily here.

What would help is:

  * report your (gnuradio and) PyOpenGL version
  * include a traceback
  * include the patch for what you changed to make it work

It *looks* like the wrapper is actually entirely unneeded these days (it 
basically duplicates the code in the automated wrapping), but without 
knowing *how* the code is failing I can't actually be sure eliminating 
the wrapper entirely would fix your problem.  From what I can see 
gnuradio is only ever calling glGenTextures(1) in a very standard/simple 
way.

Take care,
Mike

-- 
________________________________________________
   Mike C. Fletcher
   Designer, VR Plumber, Coder
   http://www.vrplumber.com
   http://blog.vrplumber.com