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

[Simon ESNEAULT]

Dear Aashish,

Yes the root cause is probably located in vtkTexturedActor2D, or in
vtkOpenGLTexture::Load( vtkRenderer* ) which looks like the responsible
class for loading the texture.
Shall I fill a bug ?
Thanks
Simon

2015-11-16 17:49 GMT+01:00 Aashish Chaudhary <aashish.chaudhary at kitware.com>
:

> I see so its not just related to volume rendering and it seems to be a
> vtkTextActor2D problem? In that can probably Ken / David Lonie wants to
> take a look at it. Nonetheless, we will follow up on this bug.
>
> - Aashish
>
> On Mon, Nov 16, 2015 at 11:12 AM, Simon ESNEAULT <simon.esneault at gmail.com
> > wrote:
>
>> Hello Aashish,
>>
>> Thanks !
>> After doing some test, I realized the patch I've just sent is not the
>> correct fix at all, because the text is not rendered properly when we don't
>> use a vtkFixedPointVolumeRayCastMapper anymore.
>>
>> I believe the problem is probably larger than this and probably has
>> nothing to do with the freetype text generation, but more with the
>> vtkTexturedActor2D rendering part used together with a
>> vtkFixedPointVolumeRayCastMapper on the new rendering backend, when the
>> texture has some transparent pixel in it ...
>>
>> Attached there is a new example that demonstrate that a vtkTextActor AND
>> a vtkTexturedButtonRepresentation2D are not correctly drawn in that case :
>> - OpenGL1 backend
>> <http://picpaste.com/pics/OGL1-Texture-okay.1447690100.png> : Transparent
>> pixel in Texture are correctly drawn
>> - OpenGL2 backend
>> <http://picpaste.com/pics/OGL2-Texture-not-okay.1447690272.png> :
>> Transparent pixel in Texture are not correctly drawn (clamped to white ?)
>>
>> The example is more simple than the previous one and does not need any
>> additional data.
>>
>> Hope that helps !
>> -Simon
>>
>> 2015-11-16 16:11 GMT+01:00 Aashish Chaudhary <
>> aashish.chaudhary at kitware.com>:
>>
>>> 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>*
>>>
>>
>>
>>
>> --
>> ------------------------------------------------------------------
>> Simon Esneault
>> Rennes, France
>> ------------------------------------------------------------------
>>
>
>
>
> --
>
>
>
> *| 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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Simon Esneault
Rennes, France
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