Re: access violation when calling glGenFramebuffers

On 13-04-04 06:21 PM, Chris Barker - NOAA Federal wrote:
> On Thu, Apr 4, 2013 at 10:31 AM, Mike C. Fletcher
> <[email protected]> wrote:
...
>> As for the original error, it *could* be that there's a problem with 64-bit
>> windows there, but I'm a bit skeptical, as 64-bit Linux doesn't show any
>> problems, and the test_core.py script actually generates a framebuffer
>> during testing if glGenFrameBuffers is available.  That's my very first
>> smoke-test for the build working on any platform.
> well, IIUC, LInux (gcc) 64 bit gives you 64 bits for and "int" and
> Windows (MSVC) gives you 23 bits for an "int", or something like that
> -- there is defiantly a difference in there somewhere (maybe it's
> long?) Anyway, I think it sure could be a non-issue on LInux, and kill
> you on windows.
I'm pretty sure we would have hit a 23-bit integer bug before this :) .  
All of PyOpenGL is using GLint = ctypes.c_int (which was taken from the 
Linux GL headers), and if my reading of the spec is correct, c_int is 
pretty close to what is meant (it should be c_long, as the minimum width 
is 32 bits, but I don't think there are any platforms we actually 
support which use 16-bit ints).

That said, now that I read up on Windows, it seems that Win64 *does* use 
different conventions for long (doesn't expand it to 64-bit, apparently) 
vs. long long, and it is possible that we have something in there 
casting to an integer or long (instead of size_t/ptr types).  There are 
a number of places where we have to do data-casts for pointers to/from 
integer-like types, and if something in those chains is of the wrong 
size, we might see an error.  I spent an hour or so getting a 
development environment set up again on Windows (my other laptop died), 
so I may be able to track down the failure if I can get some more time 
today.  I've got 64-bit Windows, but with AMD video card.

Enjoy,
Mike

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


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