Covers the pure-logic modules with no Qt event loop or GL context: BVH
build, LOD decimation, sidecar round-trip, instanced-geometry layout
constants, and Federation save/load + relative-path policy. Each test
binary compiles only the production source(s) under test, so the unit
tier doesn't pull Qt/OpenCASCADE/IfcGeom into the test build.
Gated behind BUILD_IFCVIEWER_TESTS=OFF; default builds remain offline.
Catch2 v3.5.4 is fetched on demand via FetchContent.
Turn src/ifcviewer into libIfcViewer.so holding the rendering engine +
geometry pipeline (ViewportWindow, GeometryStreamer, BvhAccel,
InstancedGeometry, SidecarCache, LodBuilder, AppSettings). Move the
existing UI shell (MainWindow, SettingsWindow, main.cpp) into
src/ifcviewer-full as the IfcViewerFull executable. Add a new
src/ifcviewer-minimal target with a MinimalWindow that hosts only the
viewport and reuses the sidecar fast-path for benchmark/debug runs.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Unexpected consequence of #7365 - previously `OPENCASCADE_LIBRARIES` supposed to be a list of libraries filepaths, but after refactor `OpenCASCADE_LIBRARIES` end up being both list of library names and list of filepaths.
And since link directories for the names was not provided, it failed to find the libraries to link.
If using OpenCASCADEconfig it wouldn't fail as cmake would evaluate library names as imported target names.
To fix it and simplify it even further, in case of manually provided paths, it now creates `OpenCASCADE_INTERFACE` target and stores it in `OpenCASCADE_LIBRARIES` - target will automatically have all the includes, library names and library dirs.
`EIgen::Eigen` target used in #7340 for linking exists only if there's a cmake config, while there are cases when there's just include directory. Added same name interface target to mimic config.
Thomas Krijnen