Installation

1. Add sphinx-vtk-xref as a project dependency or install it with:

   pip install sphinx-vtk-xref

2. Add sphinx_vtk_xref as an extension in your conf.py file used by Sphinx. The exact setup depends on whether your documentation is written in reStructuredText or Markdown.

extensions = [
    ...,
    'sphinx_vtk_xref',
]

pip install myst-parser

extensions = [
    ...,
    'sphinx_vtk_xref',
    'myst_parser',
]
source_suffix = {
    '.md': 'markdown',
}

Usage

• Add links to VTK class documentation with the :vtk: role. For example, write :vtk:`vtkImageData` in docstrings to link directly to the vtkImageData documentation. This will render as vtkImageData.

  If using MyST, use {vtk}`vtkImageData` instead.

• Link directly to class members such as methods, enums, or enum values. For example, write :vtk:`vtkImageData.GetSpacing` to link directly to the GetSpacing method. This will render as vtkImageData.GetSpacing.

  If using MyST, use {vtk}`vtkImageData.GetSpacing` instead.

• Write enum values the way they appear in code: with or without their enum, and with either separator. All four of these link to the same COMPOSITE_BLEND anchor.

  :vtk:`vtkVolumeMapper.COMPOSITE_BLEND`
  :vtk:`vtkVolumeMapper::COMPOSITE_BLEND`
  :vtk:`vtkVolumeMapper.BlendModes.COMPOSITE_BLEND`
  :vtk:`vtkVolumeMapper::BlendModes::COMPOSITE_BLEND`

  Naming the enum is required for a scoped enum class, where :vtk:`vtkProperty::Point2DShapeType::Round` is the only way to spell the value in C++.

• . and :: are interchangeable separators, and a trailing argument list is ignored, so :vtk:`vtkImageData::GetSpacing()` and :vtk:`vtkImageData.GetSpacing` are the same reference.

• Use ~ to shorten the title for the link and only show the class member after the period. For example, :vtk:`~vtkImageData.GetSpacing` will render as GetSpacing.

  If using MyST, use {vtk}`~vtkImageData.GetSpacing` instead.

• Provide a custom title for the reference. For example, :vtk:`Get Image Spacing <vtkImageData.GetSpacing>` will render as Get Image Spacing

  If using MyST, use {vtk}`Get Image Spacing <vtkImageData.GetSpacing>` instead.

• Python references to VTK classes also link to the class documentation, whatever module path they use. This covers type annotations such as -> vtkmodules.vtkCommonCore.vtkPoints in autodoc signatures, and docstring types such as points : vtkPoints. They are checked the same way as :vtk: class references.

Configuration

The following options can be set in conf.py:

vtk_xref_nitpicky

Bool, default True. Set to False to disable :vtk: link checking. This is independent of Sphinx’s own nitpicky option, so you can turn off :vtk: link validation without affecting how the rest of your project handles missing references. When disabled, the :vtk: role skips the HTTP request used to validate class and member references (and to resolve member anchors) and instead links directly to the (unvalidated) class documentation page.

vtk_xref_nitpicky = False

vtk_xref_ignored_status_codes

Collection of HTTP status codes, default {429, 500, 502, 503, 504}. These codes typically indicate a transient server-side issue (rate limiting or upstream unavailability) rather than a genuinely-invalid class reference, so they are logged as info messages and do not fail the build, even with Sphinx’s -W flag. The role falls back to the (unvalidated) class URL in this case.

vtk_xref_ignored_status_codes = {404}

Notes

• The URLs linking to the VTK documentation are checked to ensure they are valid references. A warning is emitted if the reference is invalid, but the role will still try to point to a valid URL where possible. Combine this with Sphinx’s own -W flag to fail the build on invalid links.

• A reference is resolved from its most specific component that matches, so the class must come first. A module-qualified path such as :vtk:`vtk.vtkVolumeMapper.COMPOSITE_BLEND` is not supported, and reports vtk as an invalid class.