<3 I'll try to review this as soon as I can.

The only nuance for reusing an ArrayMesh is that it either needs to disallow baking a mesh to itself; or it needs to buffer the list of surfaces, surface names and materials in a LocalVector<Array> / LocalVector<Material>, then clear the surfaces, then add them back.

@lyuma Disallow is better as the LocalVector cache for the mesh arrays and materials seem to be unable to prevent mesh corruption. As soon as the clear_surfaces() function is called on the existing mesh the data breaks for whatever reason while it works just fine with other meshes. I am not feeling it to do a full data copy of the arrays to support such edge uses.

I apologize for the request changes review. I dismissed the review comment because the comment is no longer relevant. I'll try to avoid using that in the future.

Overall, the code looks reasonable. I think there are always concerns left and right about GPU memory copies, inefficient Mesh APIs, ArrayMesh vs ImporterMesh vs SurfaceTool. Either the state of Godot's mesh APIs is in dire need of rethinking, or we need to implement a way to have a CPU-backed ArrayMesh.

Mathematically the code is fine. And usability-wise, it does look like a function that games could find useful and could be a bit slow in terms of CPU perf to recreate this in GDScript, as long as the inherently slow design involving a GPU-to-CPU copy is documented.

I would be ok if this gets merged. However, I'm not involved enough with the rendering team to make that sort of call.

Changed so that the baked mesh is always returned, and if an optional existing mesh param is provided it updates this mesh RID instead of creating a new mesh as this helps with updating instances that already use that mesh.

Thanks!

Does this actually work? I am trying to use it, but posed or animated body doesn't seem to generate a different mesh after calling in godot 4.3.

Looking for an example but the docs are bare on this one. even some sort of a unit test would be something i would like to take a peak at for how it is supposed to work.

Lookin at this in 4.4. Dev2 i dont see the mesh changing. Is there a test case or a test i can confirm before filing a bug?

I have tried many things I am using a model with and without animation. Minipulating the bones via the script. Alot of stuff i have yet to get a model that differs from the original model. I am happy to be wrong. but i cant, with the documentation i have get it to work. There is about a 80% chance i am doing something wrong, but that means the documentation is incomplete.

Are you sure you're only baking blend shapes into meshes?

As sure as i can be without and example project that shows the function working. Here is a snip of the code i am using. The character has the bones posed earlier in the code. Body is a meshInstance3d with a skeleton. it is posed several different ways. character is a child of Collection, when i add the new meshInstance3d with the new mesh, it is in the default pose regardless of the pose character was in when calling the method. I have tried in all modes (mobile, compatibility, and Forward+) i have exported the mesh as an obj and it is the same. i have tweaked other aspects of the mesh and those carry (this isnt very useful), but not the skeleton manipulations.

character.get_node("Body").bake_mesh_from_current_blend_shape_mix(baked_char)
var mesh=MeshInstance3D.new()
collection.add_child(mesh)
mesh.set_mesh(baked_char)

In the game i can see posed vs unposed.

#85018 is the pr that bakes the skeleton. This one bakes the blend shapes.