[vtkusers] Z-fighting problem on intel hd graphics

Fri Aug 26 13:25:03 EDT 2016

Thanks, I switched back to QVTKWidget and everything works as expected with your fix

Robert

From: Elvis Stansvik [mailto:elvis.stansvik at orexplore.com] 
Sent: Friday, August 26, 2016 9:08 AM
To: Róbert Špir <spir.robert at gmail.com>
Cc: VTK Users <vtkusers at vtk.org>; Ken Martin <ken.martin at kitware.com>
Subject: Re: [vtkusers] Z-fighting problem on intel hd graphics

2016-08-25 18:43 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com <mailto:elvis.stansvik at orexplore.com> >:

2016-08-25 18:36 GMT+02:00 Róbert Špir <spir.robert at gmail.com <mailto:spir.robert at gmail.com> >:

it works ok after switching to qvtkwidget2, even the multisampling under linux, which wasn’t working with qvtkwidget

Ah, that's good to know. I believe when I was having the problem, I was working through Python, so was using QVTKRenderWindowInteractor (or maybe my own similar class), which is yet another thing (QVTKWidget / QVTKWidget2 are not wrapped).

Glad it worked out anyway. Nowadays I'm using C++ and QVTKWidget2 too.

I was actually wrong. I had a look at my code, and I'm using QVTKWidget (not QVTKWidget2), and what I did to get around problems with Z-ordering and also to get multisampling working reliably was this (from the constructor of my QVTKWidget subclass):

    QSurfaceFormat surfaceFormat = windowHandle()->format();
    surfaceFormat.setSamples(8);
    surfaceFormat.setStencilBufferSize(8);
    windowHandle()->setFormat(surfaceFormat);

Hope that helps someone else using QVTKWidget.

Elvis

Elvis

From: Elvis Stansvik [mailto:elvis.stansvik at orexplore.com <mailto:elvis.stansvik at orexplore.com> ] 
Sent: Thursday, August 25, 2016 6:24 PM
To: RobertS <spir.robert at gmail.com <mailto:spir.robert at gmail.com> >
Cc: VTK Users <vtkusers at vtk.org <mailto:vtkusers at vtk.org> >; Ken Martin <ken.martin at kitware.com <mailto:ken.martin at kitware.com> >

Subject: Re: [vtkusers] Z-fighting problem on intel hd graphics

Den 25 aug. 2016 5:35 em skrev "Róbert Špir" <spir.robert at gmail.com <mailto:spir.robert at gmail.com> >:
>
> ok, everything works fine without qvtkwidget, so the problem is somewhere there

I don't remember exactly, but I think I had the same problem. Should be somewhere on this list I think.

I think it's possible to work around by manually setting the stencil buffer size on the QGLFormat used by the widget.

On the bus at the moment so have limited ability to search.

Elvis

>
>  
>
> From: Róbert Špir [mailto:spir.robert at gmail.com <mailto:spir.robert at gmail.com> ] 
> Sent: Thursday, August 25, 2016 2:56 PM
> To: 'Ken Martin' <ken.martin at kitware.com <mailto:ken.martin at kitware.com> >
> Cc: 'vtk' <vtkusers at vtk.org <mailto:vtkusers at vtk.org> >
> Subject: RE: [vtkusers] Z-fighting problem on intel hd graphics
>
>  
>
> I made a few more tests:
>
> the same problem happens with llvmpipe and with nvidia with nouveau driver
>
> doesn’t happen on nvidia binary driver or in OS X with intel or nvidia or in windows with intel or nvidia
>
> So maybe it’s a bug in mesa? Currently I’m using qt5 with qvtkwidget, I will try to create minimalistic example without qt to see if the problem is reproducible
>
>  
>
> From: Ken Martin [mailto:ken.martin at kitware.com <mailto:ken.martin at kitware.com> ] 
> Sent: Tuesday, August 23, 2016 6:45 PM
> To: RobertS <spir.robert at gmail.com <mailto:spir.robert at gmail.com> >
> Cc: vtk <vtkusers at vtk.org <mailto:vtkusers at vtk.org> >
> Subject: Re: [vtkusers] Z-fighting problem on intel hd graphics
>
>  
>
> This sounds like a driver issue. I suppose you could try setting the following environment variable
>
>  
>
> GALLIUM_DRIVER=llvmpipe
>
>  
>
> to switch to software rendering and see if the problem goes away.  If nvidia and mesa llvmpipe both work on your linux system then I would really suspect the intel linux driver.
>
>  
>
>  
>
>  
>
> On Wed, Aug 17, 2016 at 6:17 AM, RobertS <spir.robert at gmail.com <mailto:spir.robert at gmail.com> > wrote:
>>
>> Hi all,
>> I'm doing simple visualization of data on rectangular grid by creating
>> vtkpolydata from single vtktrianglestrip and when running the application in
>> linux on intel hd graphics there is serious problem with z-fighting where
>> the parts that should be far away are overlapping parts that are near the
>> camera. This doesn't happen when running on windows (intel or nvidia) or on
>> linux with nvidia
>> here you can see the problem, the camera angle is still the same
>> http://tesla.math.sk/intel1.jpg <http://tesla.math.sk/intel1.jpg>
>> http://tesla.math.sk/nvidia1.jpg <http://tesla.math.sk/nvidia1.jpg>
>> another angle
>> http://tesla.math.sk/intel2.jpg <http://tesla.math.sk/intel2.jpg>
>> http://tesla.math.sk/nvidia2.jpg <http://tesla.math.sk/nvidia2.jpg>
>> this happens on vtk 7.0 and also on vtk 7.1 from git
>> tested hardware is intel hd graphics on haswell, and ivy bridge (mesa 11.2
>> and 12.0 with opengl 3.3) and on broadwell with mesa 12.0 with opengl 4.4
>> Is this a known issue or am I doing something wrong?
>>
>>
>>
>> --
>> View this message in context: http://vtk.1045678.n5.nabble.com/Z-fighting-problem-on-intel-hd-graphics-tp5739803.html
>> Sent from the VTK - Users mailing list archive at Nabble.com.
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>
>
>  
>
> --
>
> Ken Martin PhD
>
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