[Bf-python] Doubts while porting VRM to blender 2.6x

[Antonio Ospite]

Hi,

I am trying to port VRM (http://vrm.ao2.it) to blender 2.6x and I'd
like to discuss some of the problems I am facing, in the hope that I can
save some time in case someone else has solved those problems already,
or to see if future development in blender (I am thinking to BMesh
here) could help me to keep the script more manageable. I can release
it after 2.63, 2.64 or 2.65 I am definitely not in a hurry here.

When I firstly wrote VRM I abused the Mesh and NMesh classes to
store the result of the various rendering steps (projected coordinates
of vertices, faces color, info about face visibility, etc.), this way I
could concentrate more on the algorithms and less on the data
structures.

To do that I used to sort objects in a scene and also sort faces in a
mesh according to certain criteria, removing, adding and splitting
faces; and the old NMesh class allowed some of these operations.

The new API appears to be stricter about mesh data processing: data has
to be taken out, processed and then re-added in to a mesh, and the
concept of "global" operators doesn't help me either.
On the bright side the "mathutils.geometry" module looks quite useful
to me.

I am listing here some hypothetic API I could use to keep on abusing the
blender data structures as I am doing right now :), if you have some
time to think about them I will appreciate if you could tell me if
those make sense to you too.

I could use something like:
scene.objects.sort(key=some key based on objects properties)
mesh.faces.sort(key=some key [face index?] based on faces and vertices
properties)

This would allow to do the sorting in a more flexible way,
bpy.ops.mesh.sort_faces() looks quite limited for my use case.

Moreover, I would be happy if I was able to split a face along a plane,
something like:
mesh.split_face(face_index, plane_co, plane_normal)

Currently a face has to be removed, then split and after that the two
new faces have to be added to the mesh, with unconnected duplicated
vertices if we want to limit the split to one face only; I have some
code for that inspired by mesh_looptools.py, but maybe duplicating
such functions in different scripts could be avoided.

Adding and removing individual faces could be handy too:
face = mesh.faces.pop(index)
mesh.faces.insert(new_index, face)

The question is: is there any chance that functionalities similar to the
ones I described could be added to blender? Could these be useful to
other scripts as well?

Alternatively I will end up having my own data structures for scene,
objects and meshes, which is OK too, but that is not lazy enough for
my taste.

Thanks,
   Antonio

-- 
Antonio Ospite
http://ao2.it

A: Because it messes up the order in which people normally read text.
   See http://en.wikipedia.org/wiki/Posting_style
Q: Why is top-posting such a bad thing?
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