[vtkusers] OpenGL2/vtkOpenGLTexture.cxx signal SIGSEGV, Segmentation fault

[Jorge Perez]

Hello, after investigating the pipeline (the SEGFAULT pushed me to do it) I
found how to remove the warning. The pipeline which is creating the texture
is internal to vtkImagePlaneWidget. I could remove the Warning by disabling
the TextureVisibility until a valid ImageData is set to the
vtkImagePlaneWidget.

But my concern is related to the SEGFAULT, and I wonder if vtk need to
check for the NULL value that I mentioned in this thread.

best regards,

Jorge

2016-01-25 17:59 GMT+01:00 Aashish Chaudhary <aashish.chaudhary at kitware.com>
:

> Are you sure that the pipeline that creates the texture is not broken as
> said in the warning? Looks like whatever filter / pipeline you are using is
> not producing the data as it should. And it seems to me that we could be
> check for null texture object in other methods. If no one else look at it,
> I will push a fix.
>
> - Aashish
>
> On Mon, Jan 25, 2016 at 6:00 AM, Jorge Perez <josp.jorge at gmail.com> wrote:
>
>> Hello, I have an application which is reaching a SIGSEGV when opengl
>> backend is OpenGL2 (master branch). I have traced the error and it seems to
>> be related to this kind of warning:
>>
>> Warning: Kitware/vtk.gitlab/Common/ExecutionModel/vtkAlgorithm.cxx, line
>> 1421
>> vtkOpenGLTexture (0x17e1620): Attempt to get connection index 0 for input
>> port 0, which has 0 connections.
>>
>> The warning appears with both OpenGL and OpenGL2 backends but with the
>> OpenGL2 a SIGSEGV is reached.
>>
>> The SIGSEGV is because the member vtkOpenGLTexture::TextureObject is NULL
>> and it can be used in:
>>
>>
>>    - OpenGL2/vtkOpenGLPolyDataMapper
>>
>> if (texture)
>>   {
>>   tNumComp =
>>    vtkOpenGLTexture::SafeDownCast(texture)->
>>       *GetTextureObject()->*GetComponents();
>>   }
>>
>>    - OpenGL2/vtkOpenGL2Texture.cxx
>>
>> void vtkOpenGLTexture::CopyTexImage(int x, int y, int width, int height)
>> {
>>   this->*TextureObject->*CopyFromFrameBuffer(x, y, x, y, width, height);
>> }
>>
>> void vtkOpenGLTexture::PostRender(vtkRenderer *vtkNotUsed(ren))
>> {
>>   this->*TextureObject->*Deactivate();
>> }
>>
>> I see that within there are some pice of code which test for
>> TextureObject and uses it if it is not NULL, but there are others which do
>> not do the test for NULL.
>>
>> In order to have a quick fix I have initialized  the member TextureObject
>> to vtkTextureObject::New() instead of the value 0 (at the constructor
>> vtkOpenGLTexture::vtkOpenGLTexture). That solved the SIGSEGV for my
>> application but I'm not sure if this could be a the correct solution.
>>
>> I can submit a merge request if the change make sense.
>>
>> this->TextureObject = vtkTextureObject::New();
>>
>> best regards,
>>
>> Jorge
>>
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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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