[Bf-python] BMesh upgrade docs & api info

[Matt Ebb]

Thanks for your help, Campbell - some responses below.

On Mon, Apr 23, 2012 at 10:42 AM, Campbell Barton <ideasman42 at gmail.com> wrote:
>> At the moment I'm assuming that a UV Map contains the link to a
>> per-face image, but it also seems to contain a weird collection of 4
>> 'UV Selected' properties, that I can't figure out what on earth
>> they're for. The names of UV Maps also seem to correlate with what's
>> in the UI.
>
> I don't follow, which selected properties are these?

These: http://www.pasteall.org/pic/30646

>> * Poking in the python console, I see that mesh.uv_loop_layers has an
>> 'active' property, that's not displayed in the UI in datablocks mode
>> (why?). This seems to get me the active layer selected in the UI.
>
> Because it sync's with the uv_texture.active layer... eeh, this should
> be documented too.
>
>> * UV Loop layers seem to contain the UV coordinates themselves (a uv
>> pair for each per-face-vertex 'loop') inside 'data', but I can't see
>> how to relate those to the UV Maps shown in the UI. When I iterate
>> over the uv loop layers (eg. [l for l in mesh.uv_loop_layers] ) it
>> gives me names like: bpy.data.meshes['Cube'].uv_loop_layer["UV
>> coord"]. These names are not visible in the datablocks view, and do
>> not seem to correspond to the names in the 'UV Maps' in the UI.
>
> Hope the example helps here.

Not really, I'm afraid. I understand the indices of MeshUVLoop data
are equivalent between mesh geo loops, vertex colour loops, etc. (good
to this this documented for certain now, though!).

The issue I'm having is retrieving UV Loop Layers by name, not just
the active one. I'm talking about the layers themselves, not the loop
items inside them. It's only the UV Map names that are exposed in the
UI, and the MeshUVLoopLayer names don't correspond to those names in
the UI. So far I'm going on the assumption that UV Maps and UV Loop
Layers are ordered identically, so my code looks like:

    if name == "":
        uv_loop_layer = mesh.uv_loop_layers.active
    else:
        # assuming uv loop layers and uv textures share identical indices
        idx = [i for i, uvtex in enumerate(mesh.uv_textures) if
uvtex.name == name][0]
        uv_loop_layer = mesh.uv_loop_layers[idx]

This seems to work ok, but it would be good to have clarification that
this is the right way to access UV Loop Layers by name. Perhaps it
would be simpler if the UV Loops Layers just shared names with UV
Maps? :)

thanks very much,

Matt