Documentation/Labs/VTK8

This page documents the update of Slicer to use VTK 8.0.

Status on this page is out-of-date. Since VTK8 transition will happen in conjunction with Qt5, see detailed TODO lists on Documentation/Labs/Qt5

Overview

It is planned to update the version of VTK that Slicer uses from 7.1 to 8.0.

Status

• Builds on Linux and Windows.
• Fails to build on Mac due to linker error in VTK introduced in https://gitlab.kitware.com/vtk/vtk/merge_requests/1713. Potential fix is in progress: https://gitlab.kitware.com/vtk/vtk/merge_requests/3014.
• Windows shows OpenGL errors at exit with the OpenGL backend. Likely a regression from https://github.com/Kitware/VTK/commit/49802a3d15fac9dd64feb6e86fb8d0dfc2d31a05.

   Generic Warning: In C:\path\to\S\VTKv7\Rendering\OpenGL\vtkOpenGLDisplayListPainter.cxx, line 52
   failed after ReleaseAllLists 16 OpenGL errors detected
   0 : (1282) Invalid operation
   1 : (1282) Invalid operation
   ...
   15 : (1282) Invalid operation

• VTK8 requires C++11. Because Slicer includes custom VTK classes, Slicer should also be compiled with C++11.
• On Mac, if targeting 10.7 or 10.8, likely will need to set CMAKE_CXX_FLAGS=-stdlib=libc++ for C++11 support. Note that this would require Qt build with libc++, which is officially supported by Qt5. Note: Qt 5.7.1 minimum officially supported deployment target is 10.8. Resolution: target 10.9.
• There may be picking issues with widgets. For example, the slice view ROI handles don't work correctly.
• * Windows (VS2013) may have a dependency issue related to Python wrapping. At first, wrapping seems to not use the hierarchy files or runs before they are available. Building again generates the wrapped classes correctly. (resolved)
• Update "VTKv7" project name to "VTKv8".
• Add Slicer_VTK_VERSION_MAJOR option to support building with VTK7 and VTK8, as was done for VTK5/6 in https://github.com/Slicer/Slicer/commit/50281153c57c683106498295ea82472eaa20eee4. VTK7 wrapping should not build the hierarchy files.
• EMSegment remote module will require updates to fix vtkDebugLeaks output. (updated in r17131)

Branches/Merge Requests

VTK:

• https://github.com/Slicer/VTK/commits/slicer-v8.0.0-2017-06-26-782d7ed

Slicer:

• https://github.com/msmolens/Slicer/commits/support-vtk8

Outstanding VTK issues

• Respect access specifier of using statements in wrapping: https://gitlab.kitware.com/vtk/vtk/merge_requests/2988
• OpenGL errors occur when destroying vtkWin32OpenGLRenderWindow: https://gitlab.kitware.com/vtk/vtk/issues/17076
  • Would be great to get a proper fix from the VTK team for this regression.
• Can't build VTK on Mac with -DVTK_WRAP_PYTHON:BOOL=ON -DVTK_ENABLE_KITS:BOOL=ON because libvtkWrapping-8.1.1.dylib doesn't link.
• Update Slicer/VTK branch to include upstreamed fixes

Slicer-specific VTK commits

Slicer's VTK 8.0 branch includes fixes/changes that aren't in upstream:

• Fix linking libvtkWrapping with Python wrapping and kits enabled on Mac (Merged upstream - Integrated in VTK as https://github.com/Kitware/VTK/commit/8a60be1)
  • https://github.com/Slicer/VTK/commit/cbb1269509cb32d3827adfce1795e51209132e73
• Respect access specifier of using statements in wrapping (Merged upstream - Integrated in VTK as https://github.com/Kitware/VTK/commit/5a4ddec)
  • https://github.com/Slicer/VTK/commit/93a7c677481259cf23121a053d82ba4b7c2286e6
• ENH: Allow selection of seed points using vtkSeedWidget (Merged upstream - Integrated in VTK as https://github.com/Kitware/VTK/commit/b684733)
  • https://github.com/Slicer/VTK/commit/734709ee38a0a25c92a9a0c7477cfddec5e12cf3
• Ensure vtkVariant stream associated with << operator is set back to "dec". (Merged upstream - Integrated in VTK as https://github.com/Kitware/VTK/commit/dc7c62a)
  • https://github.com/Slicer/VTK/commit/dbf5de60c0809ca6233fe428761ef19e561ef542
• BUG: WIP: fix vtkPickingManager interaction with widgets
  • https://github.com/Slicer/VTK/commit/2c55e994475b6568a5b3e7363ab70c4dd722cc5d

Test results

Windows:

Test results:

• http://slicer.cdash.org/viewTest.php?onlyfailed&buildid=1058006 (Release configuration, OpenGL backend)

Linux:

Test results:

• http://slicer.cdash.org/viewTest.php?onlyfailed&buildid=1053469 (Release configuration, OpenGL backend, Ubuntu 16.04)
  • py_StandaloneEditorWidgetTest is vtkDebugLeaks; also occurs when built with VTK7.
• http://slicer.cdash.org/viewTest.php?onlyfailed&buildid=1053471 (Release configuration, OpenGL2 backend, Ubuntu 16.04)

OS X:

Test results:

• TBD

Rendering backend

Although VTK 7 changed the default setting of VTK_RENDERING_BACKEND to OpenGL2, Slicer still explicitly sets it to OpenGL. The rendering backend in Slicer is set using Slicer_VTK_RENDERING_BACKEND.

OpenGL2 backend known issues

• Need to move OS X nightly build to new factory machine to be able to set CMAKE_OSX_DEPLOYMENT_TARGET:STRING=10.7. This will ensure that the required OpenGL version is found. See https://github.com/Slicer/Slicer/pull/595.
  • WIP PR: https://github.com/Slicer/DashboardScripts/pull/12. Will need to be updated for Qt5.
• 4252: Slicer crashes on start when started through Windows Remote Desktop

Discussion

The transition plan was announced on the Slicer forum: https://discourse.slicer.org/t/transition-to-vtk-8-0/379.

Future work

Future work in Slicer related to VTK 8 could include:

• Remove BTX/ETX markers.
• Check for and resolve build warnings in Slicer VTK classes.
• Check that settings in External_VTKv8.cmake are all still necessary, specifically VTK_USE_PARALLEL, and anything related to Qt.