add cuboid_tray_with_step model

Author: sebmestrallet

Diff for: CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - A triangle mesh (.obj), the naive labeling (.txt) and a glTF model are included for all models. The .obj can be downloaded directly from the README.
 - Links to visualize the 3D model with [3dviewer.net](https://3dviewer.net/) ([kovacsv/Online3DViewer](https://github.com/kovacsv/Online3DViewer))
+- `cuboid_tray_with_step` model
 
 ### Changed
 

Diff for: README.md

@@ -24,6 +24,7 @@ Name | Thumbnail | Files | Comments
 -----|-----------|-------|---------
 `cuboid_screw_thread` | <div align="center"><img src="cuboid_screw_thread/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/cuboid_screw_thread/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](cuboid_screw_thread/SALOME_Study.hdf) <br/> [.py](cuboid_screw_thread/SALOME_Shaper.py) <br/> [.step](cuboid_screw_thread/CAD.step) <br/> [.brep](cuboid_screw_thread/CAD.brep) <br/> [.stl](cuboid_screw_thread/CAD.stl) <br/> [.obj](cuboid_screw_thread/triangle_mesh.obj) | Introduced in [^2] and mentioned in appendices of [^3]. <br/> Labeling-based approaches [^1][^3] will collapse the two parts of the slope, constrained to the same top and bottom planes.
 `cuboid_torus_with_step` | <div align="center"><img src="cuboid_torus_with_step/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/cuboid_torus_with_step/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](cuboid_torus_with_step/SALOME_Study.hdf) <br/> [.py](cuboid_torus_with_step/SALOME_Shaper.py) <br/> [.step](cuboid_torus_with_step/CAD.step) <br/> [.brep](cuboid_torus_with_step/CAD.brep) <br/> [.stl](cuboid_torus_with_step/CAD.stl) <br/> [.obj](cuboid_torus_with_step/triangle_mesh.obj) | Introduced in [^2] I believe. <br/> Here too labeling-based approaches [^1][^3] will not detect any invalidity and crush the step into the z-axis plane.
+`cuboid_tray_with_step` | <div align="center"><img src="cuboid_tray_with_step/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/cuboid_tray_with_step/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](cuboid_tray_with_step/SALOME_Study.hdf) <br/> [.py](cuboid_tray_with_step/SALOME_Shaper.py) <br/> [.step](cuboid_tray_with_step/CAD.step) <br/> [.brep](cuboid_tray_with_step/CAD.brep) <br/> [.stl](cuboid_tray_with_step/CAD.stl) <br/> [.obj](cuboid_tray_with_step/triangle_mesh.obj) | Similar to the previous model (the step will still be crushed), but of genus 0.
 `in-volume_twist` | <div align="center"><img src="in-volume_twist/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/in-volume_twist/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](in-volume_twist/SALOME_Study.hdf) <br/> [.py](in-volume_twist/SALOME_Shaper.py) <br/> [.step](in-volume_twist/CAD.step) <br/> [.brep](in-volume_twist/CAD.brep) <br/> [.stl](in-volume_twist/CAD.stl) <br/> [.obj](in-volume_twist/triangle_mesh.obj) | Introduced in [^4] <br/> Labeling-based approaches [^1][^3] will not detect the twist. The slits prevent hex-mesh extraction algorithms from un-twisting the through-hole and pushing all distorsion towards the left and right faces.
 `in-volume_knot` | <div align="center"><img src="in-volume_knot/thumbnail.png" width="300"/><br/><a href="https://3dviewer.net/#model=https://github.com/LIHPC-Computational-Geometry/nightmare_of_polycubes/blob/main/in-volume_knot/labeled_mesh.glb" target="_blank" rel="noopener noreferrer">3D viewer ↗</a></div> | [.hdf](in-volume_knot/SALOME_Study.hdf) <br/> [.py](in-volume_knot/SALOME_Shaper.py) <br/> [.step](in-volume_knot/CAD.step) <br/> [.brep](in-volume_knot/CAD.brep) <br/> [.stl](in-volume_knot/CAD.stl) <br/> [.obj](in-volume_knot/triangle_mesh.obj) | Similar to the previous model, but the through-hole is twisting around itself.
 `pipe_helix` | <img src="pipe_helix/thumbnail.png" width="300"/> | [.hdf](pipe_helix/SALOME_Study.hdf) <br/> [.py](pipe_helix/SALOME_Shaper.py) <br/> [.step](pipe_helix/CAD.step) <br/> [.brep](pipe_helix/CAD.brep) <br/> [.stl](pipe_helix/CAD.stl) |