Re: [PyOpenGL-Users] glDeleteBuffers() and arrays.vbo

[Dan H. <Dan...@no...>]

Dan Helfman wrote:
> Mike C. Fletcher wrote:
>> Dan Helfman wrote:
>>> Exception OpenGL.error.NullFunctionError: NullFunctionError('Attempt to 
>>> call an undefined function glDeleteBuffers, check for 
>>> bool(glDeleteBuffers) before calling',) in <function doBufferDeletion at 
>>> 0x0A8892B0> ignored
>>>   
>> This sounds like the VBO is getting deleted after module cleanup?  You
>> should always have a glDeleteBuffers implementation if you have a
>> glGenBuffers implementation.  Basically this code is getting called
>> after the system has done so much cleanup that the functions aren't
>> available any more (at least, that's my interpretation).
> 
> This is happening when a VBO instance is finalized after its containing 
> object goes away. And as far as I can tell, the deleter is only being 
> called once for each VBO. So I'm not sure what else could be doing the 
> cleanup unless it's in the underlying C code. I put some prints in the 
> explicit VBO.delete() call, so I've confirmed that that's not getting 
> called.
> 
> I should mention that this is all with the 3.0.0 release.

Follow-up: Upon further investigation, turns out that this is a 
threading issue. GL and the VBOs were initialized in one thread, and 
then VBO finalization was getting triggered from a different thread. As 
soon as I changed it so that the VBO deleter only got triggered from the 
correct thread, the NullFunctionErrors went away.

Dan