[vtkusers] VTK 6.3 OpenGL2 - vtkTextActor blurred text when used with vtkFixedPointVolumeRayCastMapper

[Aashish Chaudhary]

Simon,

Thanks for the report. I will follow up with other developers on this bug.

- Aashish


On Mon, Nov 16, 2015 at 6:08 AM, Simon ESNEAULT <simon.esneault at gmail.com>
wrote:

> Hello,
>
> Trying to solve this problem, I found out that if one call
> "vtkFreeTypeTools::GetInstance()->DebugTexturesOn();" before to render a
> string with a vtkTextActor, the text is properly rendered with a yellow dot
> at the anchor point, and with a transparent gray background.
> - DebugTexturesOn : http://picpaste.com/pics/Blurred.1447668943.PNG
> - DebugTexturesOff : http://picpaste.com/pics/Not-Blurred.1447669009.PNG
>
> Now digging into the code in vtkFreeTypeTools.cxx, I suspect this is a
> blending problem. When we activate Texture Debugging, a gray background is
> first drawn, and after that in the method RenderCharacter( ... ) line 1887;
> we either blend the rendered text with the background or not.
>
> Attached is a diff file that solves the problem for me. I do not really
> understand why, so maybe a developer with more VTK's knowledge can
> integrate this properly :)
>
> Thanks,
> Simon
>
>
>
> 2015-11-13 16:43 GMT+01:00 Simon ESNEAULT <simon.esneault at gmail.com>:
>
>> Hi All,
>>
>> All vtkTextActor are rendered blurred when using with
>> vtkFixedPointVolumeRayCastMapper in the same renderer in vtk 6.3 with the
>> new rendering backend.
>>
>> Here are some snapshots :
>>  - OpenGL1 <http://picpaste.com/pics/OGL1-not-blurred.1447428990.png>
>>  - OpenGL2 <http://picpaste.com/pics/OGL2-blurred.1447429027.png>
>>
>> Attached some code that reproduces the problem, to be used with this
>> <https://www.dropbox.com/s/ptqwi0ebv75kt35/volume.zip> volume. Visible
>> on OSX and Windows to our knowledge, probably on more OS.
>>
>> The text is rendered properly when used with the old backend or when
>> using a vtkGPUVolumeRayCastMapper instead of
>> the vtkFixedPointVolumeRayCastMapper.
>>
>> Shall I feel a bug, is this a known issue ?
>>
>> Thanks,
>> Simon
>>
>> --
>> ------------------------------------------------------------------
>> Simon Esneault
>> Rennes, France
>> ------------------------------------------------------------------
>>
>
>
>
> --
> ------------------------------------------------------------------
> Simon Esneault
> Rennes, France
> ------------------------------------------------------------------
>
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-- 



*| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
*| http://www.kitware.com/company/team/chaudhary.html
<http://www.kitware.com/company/team/chaudhary.html>*
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