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

[Aashish Chaudhary]

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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