📝 Pull Request Summary

This pull request introduces a new method SolverFIT3D.inspect that allows to interactively show and hide the imported solids, beam and integration path in the simulation box using pyvista's checkbox widgets. It includes several improvements and refactors to the workflow setup and the 3D grid and geometry handling code, with a particular focus on STL/STEP file handling, plotting tests, and offscreen rendering support. The most significant changes include updating the test infrastructure for offscreen plotting, refactoring STL/STEP extraction utilities, and improving the grid initialization and STL color assignment logic.

🔧 Changes Made

Visualization Improvements

• Updated visualization methods (plot_solids, plot_stl_mask, and added new method inspect) to support the smooth_shading parameter, streamline color assignment, and remove redundant color mapping logic. This allows more flexible and direct color specification for STL solids. New method solver.inspect allows to interactively show and hide the imported solids, beam and integration path in the simulation box.

Test infrastructure:

• Updated all test workflows and plotting tests to support offscreen rendering by adding a flag_offscreen variable and using it consistently in plotting functions. Output images are now saved to dedicated folders for each test. (tests/test_003_planewave_sphere.py, tests/test_007_mpi_lossy_cavity.py, tests/test_008_3D_plotting.py) [1] [2] [3] [4] [5]

• Added a new comprehensive 3D plotting test suite in tests/test_008_3D_plotting.py, covering grid inspection, solid plotting, STL mask visualization, solver inspection, and 3D field plotting, all with offscreen output.

STL/STEP extraction and file handling:

• Refactored STL/STEP extraction utilities in wakis/geometry.py to accept optional output paths, improved naming conventions, and made file export logic more robust. Functions now handle cases where no path is provided and ensure correct file naming and export. (extract_solids_from_stp, generate_stl_solids_from_stp) [1] [2] [3] [4]

Grid initialization and STL color assignment:

• Refactored grid initialization in wakis/gridFIT3D.py by renaming several internal methods for clarity (prefixing with _), improving STL color assignment logic to handle dicts, lists, and single color strings robustly, and ensuring colors are assigned to all solids. [1] [2] [3]

Workflow setup for VTK:

• Updated all GitHub Actions workflows to uninstall the default vtk package and install vtk-osmesa from a custom wheel index, ensuring compatibility with offscreen rendering. (.github/workflows/manual_tests_CPU.yml, .github/workflows/nightly_tests_CPU.yml, .github/workflows/pull_request_CPU.yml) [1] [2] [3]

Minor code cleanup:

• Improved imports and removed unused variables in test files for clarity and maintainability, following RUFF linter and CodeQL suggestions.

✅ Checklist

• Code follows the project's style and guidelines
• Added tests for new functionality
• Updated documentation (mentioned in docs/ or included in examples/ and notebooks/)
• Verified that changes do not break existing functionality (automatic tests passing)

📌 Related Issues / PRs

Closes #24