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

Fri Nov 20 08:26:33 EST 2015

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
>>>>>>> ------------------------------------------------------------------
>>>>>>>
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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
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