[vtkusers] vtkOpenGLClearErrorMacro() never returns

Tue Apr 15 11:07:49 EDT 2014

IMO, a number of 10 should be reasonable. glGetError call is an expensive
call and if that's happening at the exit, that may be Ok but not while the
application is active.

Also, typically you run into 2-3 error codes (at least my experience). It
would be nice if this could be an option that you can pass to the macro.

Just my thoughts.

-Aashish

On Tue, Apr 15, 2014 at 10:57 AM, Bill Lorensen <bill.lorensen at gmail.com>wrote:

> Hmmm. I can put a limit on the number of times the while loops execute,
> but I'm not sure what that limit should be. There are many possible gl
> errors (and glu errors)
>
>
>
> On Tue, Apr 15, 2014 at 8:59 AM, Marco Sambin <m.sambin at gmail.com> wrote:
>
>> Great Bill,
>>
>> thanks for your comments and thank you in advance for the patch.
>> Best regards,
>>
>> Marco
>>  Il 15/apr/2014 14:42 "Bill Lorensen" <bill.lorensen at gmail.com> ha
>> scritto:
>>
>>  It seems risky to have glGetError in a while loop without a guard to
>>> stop the loop. According to the open GL Super Bible, the safe way to clear
>>> the error is:
>>> GLenum glError;
>>> unsigned int i = 0;
>>>   do
>>>     {
>>>     glError = glGetError();
>>>     ++i;
>>>     }
>>>   while(i < 6 && glError != GL_NO_ERROR);
>>>
>>> I have see some docs that say there can be more  error codes. Certainly,
>>> some upper bound should be set.
>>>
>>> I'll prepare a patch.
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Tue, Apr 15, 2014 at 5:58 AM, Richard Whitehead <
>>> richard.whitehead at vivosight.com> wrote:
>>>
>>>> Marco,
>>>> Thanks for the support!  I only get it on one of my computers, where
>>>> OpenGL is issuing warnings, but then the purpose of this code is to clear
>>>> warnings...  It simply doesn't work.  Hopefully someone who knows what it's
>>>> doing could fix it.
>>>> Thanks again,
>>>> Richard
>>>>
>>>>
>>>> On 15 April 2014 10:49, Marco Sambin <m.sambin at gmail.com> wrote:
>>>>
>>>>> Hi Richard,
>>>>>
>>>>> quite a while ago, while I was making experiments with the use of JOGL
>>>>> with VTK under Windows, I encountered the same issue that you describe.
>>>>>
>>>>> Basically, in some cases my application got stuck, and the CPU usage
>>>>> went up to 25% (I have a quad core processor on my dev PC). I discovered
>>>>> this was due to a "vtkClearOpenGLErrors()" call in the rendering pipeline,
>>>>> which was iterating indefinitely in its "while" loop. Not sure what was the
>>>>> real cause of this, did not have the time to debug in detail. At that time,
>>>>> I worked around the problem by setting the VTK_REPORT_OPENGL_ERRORS option
>>>>> to "false" on CMake (which forces the implementation of
>>>>> vtkClearOpenGLErrors() to be empty). I understand that this may not be a
>>>>> viable workaround in your case, and I also believe it would be good to
>>>>> understand the real cause for this infinite loop inside
>>>>> vtkClearOpenGLErrors().
>>>>>
>>>>> But for now, I can only let you know that "you are not alone" ;-)
>>>>>
>>>>> Maybe someone else on the list can shed some more light or share some
>>>>> experience about this issue.
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Marco
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Apr 14, 2014 at 1:04 PM, Richard Whitehead <
>>>>> richard.whitehead at vivosight.com> wrote:
>>>>>
>>>>>>
>>>>>> This new macro was introduced in 6.1.0.  It is getting called when my
>>>>>> app exits and it sits in an infinite loop.
>>>>>> The documentation say is t is supposed to silently clear errors, but
>>>>>> it is not doing this.
>>>>>>
>>>>>> Please can anyone suggest how to fix it?  Since my app is closing I
>>>>>> am willing to discard errors, but the only method I can see that should
>>>>>> clear errors is, well, vtkOpenGLClearErrorMacro...
>>>>>>
>>>>>> Many thanks,
>>>>>>
>>>>>> Richard
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>>
>>>>>> Richard Whitehead *–* Senior Imaging Engineer
>>>>>>
>>>>>> *Michelson Diagnostics Ltd*
>>>>>>
>>>>>> *M:* +44 (0)7905 955276   *T:* +44 (0)20 8308 1695
>>>>>>
>>>>>> *E: *richard.whitehead at vivosight.com   *W:* www.vivosight.com
>>>>>>
>>>>>>
>>>>>> <http://www.vivosight.com/>
>>>>>>
>>>>>>
>>>>>> Michelson Diagnostics Ltd, 1 Grays Farm Production Village, Grays
>>>>>> Farm Road, Orpington, Kent  BR5 3BD, UK
>>>>>>
>>>>>> Registered Office: 3 Shearwater, Maidstone, ME16 0DW.     Registered
>>>>>> in England No. 5732681
>>>>>>
>>>>>> _______________________________________________
>>>>>> Powered by www.kitware.com
>>>>>>
>>>>>> Visit other Kitware open-source projects at
>>>>>> http://www.kitware.com/opensource/opensource.html
>>>>>>
>>>>>> Please keep messages on-topic and check the VTK FAQ at:
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>>>>>>
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>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> Richard Whitehead *–* Senior Imaging Engineer
>>>>
>>>> *Michelson Diagnostics Ltd*
>>>>
>>>> *M:* +44 (0)7905 955276   *T:* +44 (0)20 8308 1695
>>>>
>>>> *E: *richard.whitehead at vivosight.com   *W:* www.vivosight.com
>>>>
>>>>
>>>> <http://www.vivosight.com/>
>>>>
>>>>
>>>> Michelson Diagnostics Ltd, 1 Grays Farm Production Village, Grays Farm
>>>> Road, Orpington, Kent  BR5 3BD, UK
>>>>
>>>> Registered Office: 3 Shearwater, Maidstone, ME16 0DW.     Registered in
>>>> England No. 5732681
>>>>
>>>> _______________________________________________
>>>> Powered by www.kitware.com
>>>>
>>>> Visit other Kitware open-source projects at
>>>> http://www.kitware.com/opensource/opensource.html
>>>>
>>>> Please keep messages on-topic and check the VTK FAQ at:
>>>> http://www.vtk.org/Wiki/VTK_FAQ
>>>>
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>>>>
>>>
>>>
>>> --
>>> Unpaid intern in BillsBasement at noware dot com
>>>
>>
>
>
> --
> Unpaid intern in BillsBasement at noware dot com
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
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-- 
| Aashish Chaudhary
| R&D Engineer
| Kitware Inc.
| www.kitware.com
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