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

Fri Nov 20 09:37:34 EST 2015

That is the standard blend save/restore code so I think that should do the
trick. Thanks for digging into it.

On Fri, Nov 20, 2015 at 8:32 AM, Aashish Chaudhary <
aashish.chaudhary at kitware.com> wrote:

> Hi Simon,
>
> Thanks! I am okay with merging this change but in general restoring to
> previous state is tricky as for that you need to know the previous state. I
> think restoring to a default state (which you did) makes more sense.
> Although in VTK we don't have clear guideline on this. I am reviewing your
> changes..
>
>
> On Fri, Nov 20, 2015 at 8:26 AM, Simon ESNEAULT <simon.esneault at gmail.com>
> wrote:
>
>> Hello,
>>
>> I've created a merge request for this bug :
>> https://gitlab.kitware.com/vtk/vtk/merge_requests/932
>>
>> The class vtkOpenGLRayCastImageDisplayHelper is changing OpenGL blend
>> state, but never restores the state as it was before, resulting in some
>> incorrect blend later.
>> I don't know if it's the correct fix, but it certainly look like the
>> reason for this bug, and it solve the bug here.
>> Can someone review this merge ?
>>
>> Regards
>> Simon
>>
>>
>> 2015-11-18 9:38 GMT+01:00 Simon ESNEAULT <simon.esneault at gmail.com>:
>>
>>> Morning !
>>>
>>> http://www.vtk.org/Bug/view.php?id=15838
>>>
>>> Let me know if there is anything I can do to solve this.
>>>
>>> Simon
>>>
>>> 2015-11-17 16:50 GMT+01:00 Aashish Chaudhary <
>>> aashish.chaudhary at kitware.com>:
>>>
>>>>
>>>>
>>>> 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
>>>>>>>>> ------------------------------------------------------------------
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> Powered by www.kitware.com
>>>>>>>>>
>>>>>>>>> Visit other Kitware open-source projects at
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>>>>>>>>>
>>>>>>>>> Please keep messages on-topic and check the VTK FAQ at:
>>>>>>>>> http://www.vtk.org/Wiki/VTK_FAQ
>>>>>>>>>
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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>*
>>>>
>>>
>>>
>>>
>>> --
>>> ------------------------------------------------------------------
>>> Simon Esneault
>>> Rennes, France
>>> ------------------------------------------------------------------
>>>
>>
>>
>>
>> --
>> ------------------------------------------------------------------
>> 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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>
>

-- 
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