OpenLB Bridge Plan and Linux Handoff

This page captures the current DDS-to-OpenLB plan and status in a repo-tracked location so work can continue on another computer or a later time.

Current status

Implemented:

• DDS externalAttributes on retained objects
• public DDS metadata API for setting, reading, clearing, and enumerating external attributes
• DDJ/DDY serialization for external attributes
• analytic DDS-to-material bridge MVP for retained:
  • box
  • sphere
  • cylinder
  • cone
  • torus
  • transform chains
  • set-union, set-intersection, set-difference
• exported bridge entry points in src/wx_bgi_openlb.h
• C++-only OpenLB helper layer in src/wx_bgi_openlb.h for materializing DDS bridge results directly onto OpenLB SuperGeometry<T,2> and SuperGeometry<T,3> cells
• DDS-side material preview demo
• real OpenLB-coupled smoke demo on Linux using a DDS-authored 2D obstacle, OpenLB flow solve, and live wxbgi_field_* visualization
• real OpenLB-coupled 3D duct demo on Linux using DDS-authored retained geometry, OpenLB flow solve, a longitudinal slice view, and an orbiting 3D geometry panel with --wireframe / --flat / --smooth rendering and runtime 1 / 2 / 3 mode switches
• DDS/OpenLB bridge tests
• user-facing docs for the new workflow

Linux validation

Following design strategy works on Linux against the latest public OpenLB release repository checkout.

Validated flows:

1. custome designed and retained DDS geometry and tag it with openlb.* metadata
2. materialize that retained geometry onto an OpenLB SuperGeometry<T,2> using wxbgi_openlb_materialize_super_geometry_2d(...)
3. run a compact 2D channel + obstacle case in examples/cpp/wxbgi_openlb_coupled_smoke.cpp
4. materialize retained DDS sieve geometry onto an OpenLB SuperGeometry<T,3> using wxbgi_openlb_materialize_super_geometry_3d(...)
5. run a compact 3D duct + vent case in examples/cpp/openlb-demo/wxbgi_openlb_pipe_3d_demo.cpp
6. render live scalar/vector fields and DDS geometry with the existing wxbgi_field_* helpers plus the retained 3D DDS renderer

Observed results:

Platform / OpenLB tree	Result
latest public GitLab release tree	Linux build + focused OpenLB bridge tests pass
1.9.0 native Windows/MSVC	fails early on compiler builtin / feature-detection assumptions
1.6.0 native Windows/MSVC	gets much further, but still fails in OpenLB itself on Unix-only headers such as unistd.h

Conclusion: the DDS bridge MVP and the fully coupled 2D Linux path are working in this repository, but native Windows/MSVC remains blocked by upstream/toolchain compatibility.

Important files

File	Purpose
src/bgi_openlb_bridge.h / src/bgi_openlb_bridge.cpp	internal analytic DDS material bridge
src/bgi_openlb_bridge_api.cpp	exported bridge wrappers
src/wx_bgi_openlb.h	public OpenLB-facing helper header plus C++ materialization helpers
examples/cpp/wxbgi_openlb_material_preview_demo.cpp	DDS-side authoring and preview demo
examples/cpp/wxbgi_openlb_coupled_smoke.cpp	real OpenLB-coupled 2D channel + obstacle demo
examples/cpp/openlb-demo/wxbgi_openlb_pipe_3d_demo.cpp	real OpenLB-coupled 3D duct + orbit preview demo
examples/cpp/openlb-demo/run_openlb_pipe_3d_demo.sh	Debian/Ubuntu/WSL2 bootstrap script for the 3D OpenLB demo
examples/cpp/openlb-demo/run_openlb_pipe_3d_demo_macos.sh	macOS/Homebrew bootstrap script for the 3D OpenLB demo
examples/cpp/test_openlb_bridge_materialize_2d.cpp	current bridge regression test
docs/user-guide/OpenLB-Support.md	user-facing workflow and platform status

Linux continuation checklist

On the Linux machine:

1. clone this repository and checkout the working branch
2. clone the latest public OpenLB release repository
3. point OPENLB_ROOT at that checkout
4. configure with -DWXBGI_ENABLE_OPENLB=ON
5. build the focused OpenLB demos
6. run the focused OpenLB bridge tests

Suggested commands:

git clone git@github.com:Andromedabay/wx_bgi_graphics.git
cd wx_bgi_graphics
 
git clone https://gitlab.com/openlb/release.git ../openlb-release
 
cmake -S . -B build_openlb \
  -DCMAKE_BUILD_TYPE=Debug \
  -DWXBGI_ENABLE_OPENLB=ON \
  -DOPENLB_ROOT=../openlb-release
 
cmake --build build_openlb -j --target \
  wxbgi_openlb_coupled_smoke \
  wxbgi_openlb_pipe_3d_demo \
  test_dds_external_attrs \
  test_openlb_bridge_materialize_2d \
  wxbgi_openlb_material_preview_demo
 
ctest --test-dir build_openlb --output-on-failure -R \
  "test_dds_external_attrs|test_openlb_bridge_materialize_2d|wxbgi_openlb_material_preview_demo|wxbgi_openlb_coupled_smoke|wxbgi_openlb_pipe_3d_demo"

Or use the repo-tracked bootstrap script:

examples/cpp/openlb-demo/run_openlb_pipe_3d_demo.sh --test

On macOS, use the Homebrew-oriented companion script:

examples/cpp/openlb-demo/run_openlb_pipe_3d_demo_macos.sh --test

If one coupled OpenLB target needs focused iteration, build it directly:

cmake --build build_openlb --target wxbgi_openlb_coupled_smoke -j
cmake --build build_openlb --target wxbgi_openlb_pipe_3d_demo -j