Import VolumeRover3 application from libcvc

[transfix]

What this is

Executes goal G4 (near-term-goals-2026-07-15): the VolumeRover3 application moves out of transfix/libcvc into this repository (at volrover3/), which will eventually supersede VolRover 2.0. libcvc stays a lean SDK. Counterpart PR: transfix/libcvc#102

History decision (flagged for review)

Plain copy, no git-history rewrite. Sources/headers/icons/docs are imported verbatim from libcvc commit 03b4f961f834c46fcd19b9b4b633dc4c1c8bdcfc (master); the provenance is recorded in the import commit message. Their full history remains in transfix/libcvc. Object if you would rather have the history carried over via filter-repo.

VolRover 2.0 coexistence guarantee

VolRover 2.0 target unchanged and still builds; volrover3 is additive behind BUILD_VOLROVER3 (default OFF). No 2.0 sources, targets, or CMake wiring were removed, renamed, or rewired — the only top-level CMakeLists.txt change is a new gated block appended at the end. Verified: a fresh default configure (cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release, BUILD_VOLROVER3 unset) configures and fully builds bin/VolumeRover2 (448/448 targets) on this branch.

Layout and CMake design

• volrover3/ — app sources (verbatim), tests/, inc/volrover3/ (so #include <volrover3/...> keeps working), share/ (desktop file + icons), cmake/Info.plist.in, docs/ (GRAPHICS_SYSTEM, GRAPHICS_DATA_DRIVEN_UPDATES, APPSTATE_CALLBACKS)
• libcvc is consumed as an external SDK: find_package(cvc CONFIG REQUIRED) → links the exported, namespaced cvc::cvc target (libcvc installs lib/cmake/cvc/cvcConfig.cmake + cvcTargets.cmake, namespace cvc::). The in-tree build already linked an alias with the same name, so the link lists are unchanged.
• Own project(volrover3 VERSION 3.2.4) scope, C++20 (2.0 tree stays C++17); Qt6 with Qt5 fallback; find_package(VTK REQUIRED) + vtk_module_autoinit
• Tests: installed GTest if available, else FetchContent googletest v1.14.0; VOLROVER3_BUILD_TESTS (default ON)
• Packaging ported: Linux .desktop + hicolor icon installs, macOS bundle + macdeployqt hook, Windows icon .rc + $<TARGET_RUNTIME_DLLS> + GET_RUNTIME_DEPENDENCIES walker (now seeded with the imported cvc::cvc DLL directory) + windeployqt hook; registers a volrover3 CPack component when the top level has included CPack (cpack -D CPACK_COMPONENTS_ALL=volrover3). verify-windows-deps.ps1 carried to .github/scripts/ for future packaging CI.

Verification (Linux, this machine)

• Default configure (volrover3 OFF): passes; VolumeRover2 builds fully (448 targets)
• BUILD_VOLROVER3=ON configure against a real installed SDK (libcvc dist-cvcpkg 3.2.4+cvc.1 tarball extracted to /tmp/libcvc-sdk) with CMAKE_PREFIX_PATH="<sdk>;<cvcpkg deps prefix>" (Qt6 + VTK 9.5 + Boost 1.86 + CGAL 6 + HDF5 + libiimod from the deps prefix): passes
• volrover3 app builds and links against the external cvc::cvc
• All 14 volrover3 unit tests pass (ctest --test-dir build/volrover3, QT_QPA_PLATFORM=offscreen)
• App was not launched interactively (headless verification only)

Two workarounds were needed for the combined (2.0 + 3) configure on this machine, both pre-existing 2.0 fragilities surfaced by adding a foreign CMAKE_PREFIX_PATH, not regressions from this PR:

• -DDISABLE_CGAL=ON (a 2.0 option): src/cvcraw_geometry/CMakeLists.txt does include(${CGAL_USE_FILE}), which breaks when the prefix supplies CGAL 6 (UseCGAL was removed upstream). volrover3 itself gets CGAL through libcvc's config.
• -Dlog4cplus_DIR=/usr/lib/x86_64-linux-gnu/cmake/log4cplus: the cvcpkg deps prefix ships a log4cplus config that only defines log4cplus::log4cplusS (static), shadowing the system package whose log4cplus::log4cplus target 2.0 links.

Known gaps / follow-ups

• No CI job for volrover3 in this repo yet (the packaging pipelines — AppImage/deb/dmg/NSIS — were removed from libcvc CI and need to be recreated here against an installed SDK; verify-windows-deps.ps1 is already in place)
• NSIS/DEB metadata for a separate volrover3 end-user installer was not merged into VolRover 2.0's existing monolithic CPack config; with BUILD_VOLROVER3=ON, plain cpack will include volrover3 in the VolumeRover package, and cpack -D CPACK_COMPONENTS_ALL=volrover3 packages it alone
• Depends on libcvc PR #102's small SDK fix (always install the vendored xmlrpc/ headers); SDK tarballs built before that fix need inc/xmlrpc added manually to compile volrover3