[codex] Add PLY meshfile support

[mickaelbegon]

Summary

Adds PLY meshfile support alongside the existing STL/OBJ/VTP/bioMesh readers.

• Makes meshfile extension dispatch case-insensitive.
• Reworks the ASCII PLY reader to parse the header explicitly, read vertex x/y/z properties, ignore extra properties, and read face vertex_indices / vertex_index lists.
• Triangulates polygonal PLY faces into MeshFace triangles.
• Adds a .PLY fixture and a MeshFile.FileIoPly test covering uppercase extension handling and quad-face triangulation.

Validation

• git diff --check
• Attempted cmake --build build-vitpose-conda, but the local build currently fails in libc++ headers before project code completes (__builtin_ctzg / __builtin_clzg missing). The same toolchain issue appears while compiling unrelated files such as Joints.cpp.
• ctest -N in build-vitpose-conda reports Total Tests: 0.

---

This change is 

[EveCharbie]

@pariterre @mickaelbegon is this ready for review ?

[mickaelbegon]

yes. I think so

[pariterre]

Hello :)

Triangulates polygonal PLY faces into MeshFace triangles.

What does that mean? MeshFace does not seem to be called in the code?

@pariterre reviewed 9 files and all commit messages, and made 2 comments.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on mickaelbegon).

---

src/ModelReader.cpp line 2282 at r1 (raw file):

             ++iProperty) {
          const PlyProperty &property(element.properties[iProperty]);
          if (property.isList) {

Please add a test for when it is not a list

[mickaelbegon]

Thanks for the review :)

I added coverage for the non-list face property case in cube.PLY: the face element now has a scalar material property after the vertex_indices list, so the reader exercises the branch that skips scalar face properties.

About the wording in the PR body: by “triangulates polygonal PLY faces into MeshFace triangles”, I meant that a PLY face with more than 3 vertices is split into triangles and added through Mesh::addFace({ ... }). That overload constructs a MeshFace internally, so the stored mesh still uses the existing triangular MeshFace representation.

[mickaelbegon]

Small follow-up: the coverage build also showed that the new test needs the complete MeshFace type when calling faces().size(), so I added the missing RigidBody/MeshFace.h include as well.

[EveCharbie]

"triangulates polygonal PLY faces into MeshFace triangles".
@pariterre for vtp files, we have always done this outside of biorbd. I think the reason is that we want to write new triangular mesh files instead of repeating this triangulation process each time we load the biorbd model because it is long.
@mickaelbegon If we decide that this job belongs to biorbd, could you please open an issue to try to generalize the triangulation you have added to other file formats ?

[EveCharbie]

@pariterre could you follow up on this when you have time ? (I am ready on the BioBuddy side, so making a release once it is merged would be nice)

[pariterre]

@pariterre reviewed 2 files and all commit messages, made 1 comment, and resolved 1 discussion.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on mickaelbegon).

[pariterre]

@mickaelbegon GG :)

@EveCharbie do you need a release of Biorbd?

[EveCharbie]

Thanks !
Yes please :)

[pariterre]

@pariterre reviewed 1 file and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on mickaelbegon).