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

[Aashish Chaudhary]

On Tue, Nov 17, 2015 at 3:36 AM, Simon ESNEAULT <simon.esneault at gmail.com>
wrote:

> 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 ?
>

Yes, please.

- Aashish


> 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>*
>>
>
>
>
> --
> ------------------------------------------------------------------
> 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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