[vtkusers] VTK 8.0.0 OpenGL2 Invisible surfaces

[Ken Martin]

Show me an example and maybe I can show you what VTK thinks is translucent.
Sometimes folks forget about LUTs and textures which can include
transparency.

Alternatively if you set ForceOpaque and the problem goes away, then that
confirms it.



On Fri, Jul 21, 2017 at 12:19 PM, Sophonet <vtk12af6bc42 at kant.sophonet.de>
wrote:

> I can confirm this and have seen the exact same effect here on OpenGL2.
> Likewise, I do not have any transparency set in my colors. Interestingly,
> it does not happen to all vtkPolyData objects that I have, but only to some
> of them.
>
> The platform is similar to mine and I can add that the problem also occurs
> when having openGL Mesa-library-dlls extracted in the executable folder, so
> it does not seem to be a driver problem.
>
> So it might actually be a bug in VTK?
>
>
> On 2017-07-21 11:21, Taron wrote:
>
>> Hi there,
>>
>> I have found a strange thing switching to the new Backend OpenGL2. When I
>> render surfaces it seems that only one side of a face is rendered and the
>> other is not. Front & Backface-Culling is off for those Actors.
>> This worked perfectly fine with the old Backend. Strangely enough when I
>> turn on Depth-Peeling in the renderer the faces are rendered correctly,
>> although none of the actors has any transparency set to it.
>> It is not driver related because I can reproduce this behaviour with mesa
>> drivers as well.
>> Everything takes place under Windows 10. It is an x64 Qt (5.9) app and im
>> using the QVTKWidget.
>> I also tried the QVTKOpenGLWidget, but it has the same issues.
>>
>> Any hints what goes wrong here?
>>
>>
>>
>>
>>
>> --
>> View this message in context:
>> http://vtk.1045678.n5.nabble.com/VTK-8-0-0-OpenGL2-Invisible
>> -surfaces-tp5744093.html
>> Sent from the VTK - Users mailing list archive at Nabble.com.
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-- 
Ken Martin PhD
Distinguished Engineer
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065

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