[PyOpenGL-Devel] glReadPixels with null pointer

[Tim Sheerman-C. <ord...@sh...>]

On 04/09/13 22:05, pyo...@li... wrote:
> On 13-09-02 01:59 PM, Tim Sheerman-Chase wrote:
>> >Hi all,
>> >
>> >I had problems when using glReadPixels when the data buffer pointer
>> >passed to the function is zero:
>> >
>> >glReadPixels(0, 0, capSize[0], capSize[1], GL_BGRA, GL_UNSIGNED_BYTE, 0)
> Hi Tim,
>
> I've merged your patch into bzr head, though with some modifications, as
> "if array != 0:" will trigger "cannot determine the scalar value of an
> array" errors when array is a numpy array (it creates a boolean array of
> size of array then attempts to determine whether array is True/False and
> blows up).
>
That seems sensible to me. However, I am still having problems with the 
current trunk version #623 when using glReadPixels in the previously 
described situation. I did a quick hack to try to fix it but I am unsure 
if this does not break something else. 
https://code.launchpad.net/~thetourist/pyopengl/tim2

My code breaks if the ctypes pointer created by ctypes.c_void_p is 
passed through arrayType.voidDataPointer. I have skipped this step. I am 
a little unclear as to what what would be returned in each of the cases 
and it might be worth checking.

Thanks,

Tim