This project is a fork of the VXL source hosted at https://github.com/vxl/vxl.git.

This project contains the changes required to vendor VXL's VNL libraries into ITK. ITK consumes a filtered subtree of this fork (primarily core/vnl, core/vxl_config.h.in, vcl, and the v3p/netlib BLAS/LAPACK sources) through Modules/ThirdParty/VNL/UpdateFromUpstream.sh. The overlay carries the ITK-relevant modernization and build patches that have not yet landed in upstream VXL.

Each fork branch is named with the pattern for/itk-vxl-VERSION-SHA{7}

where:

• VERSION is the upstream VXL release the ITK overlay is built on (e.g. 3.5.0), or master when the overlay is based on the upstream master tip rather than a tagged release.
• SHA{7} is the 7-character commit hash of the upstream base commit.

For example, for/itk-vxl-master-30cfa52 carries the ITK overlay on top of upstream master at commit 30cfa52.

The default branch of this fork is welcome, an orphan branch holding only this document. ITK pins a specific commit of a for/itk-vxl-* branch via the tag variable in Modules/ThirdParty/VNL/UpdateFromUpstream.sh.

Additional documentation on developing ITK: https://docs.itk.org/en/latest/contributing/index.html

See also ITK's Third-Party Fork Conventions.

1. Clone (or reuse) the fork and ensure the tree is clean:

git clone https://github.com/InsightSoftwareConsortium/vxl.git
cd vxl

2. Wire the upstream remote:

git remote add upstream https://github.com/vxl/vxl.git

3. Fetch:

git fetch origin
git fetch upstream

4. Choose the upstream base. VXL has no recent release cadence, so the overlay is normally built on the upstream master tip. Derive the base SHA and the branch name:

git fetch upstream master
SHA=$(git rev-parse --short=7 upstream/master)
echo "SHA [${SHA}]"

# Use the upstream release version when basing on a tag; use "master" otherwise.
ITK_VXL_TARGET_VERSION=master
NEW_BRANCH="for/itk-vxl-${ITK_VXL_TARGET_VERSION}-${SHA}"
echo "NEW_BRANCH [${NEW_BRANCH}]"

git switch -c "${NEW_BRANCH}" upstream/master

5. Re-integrate the ITK overlay. The overlay is the set of VXL changes ITK needs that are not yet upstream. These are tracked as open VXL pull requests; merge each with a --no-ff merge commit that records its PR number so the topology stays auditable:

# For every open ITK-relevant VXL PR (head branch fetched into a remote):
git merge --no-ff <remote>/<pr-head-branch> \
    -m "Merge vxl/vxl#<N>: <pr title>"

As each PR lands upstream, drop it from the overlay on the next update; the goal is to shrink the overlay to empty over time.

6. Push the new branch and update ITK:

git push origin "${NEW_BRANCH}"

In ITK, set both the repo and tag variables in Modules/ThirdParty/VNL/UpdateFromUpstream.sh:

readonly repo="https://github.com/InsightSoftwareConsortium/vxl.git"
readonly tag="for/itk-vxl-master-${SHA}"

Then run Modules/ThirdParty/VNL/UpdateFromUpstream.sh from a clean ITK checkout to refresh the vendored subtree, and commit the result following ITK's third-party update conventions.