[Bf-python] BMesh API

[Treyer Lukas]

Dear mailing list readers

For some reason the only doc I found yesterday on google about custom layers was "blah blah" in the the BMesh API<http://www.blender.org/documentation/blender_python_api_2_63_5/bmesh.types.html#bmesh.types.BMVertSeq.layers>.
Now with the the help of CoDEmanX, I discovered custom layers in Bmesh.

Just for clarification for "dumb" readers like me (an extension to the BMesh API Doc<http://www.blender.org/documentation/blender_python_api_2_63_2/bmesh.html#customdata-access>):

bm.verts, bm.edges, bm.faces are not just a lists but they are of type
bmesh.types.BMVertSeq, bmesh.types.BMEdgeSeq, bmesh.types.BMFaceSeq

The access to custom data of a vert for instance is implemented in bmesh.types.BMVert
and bmesh.types.VertSeq together.

Let's say you want to store the coordinates of a bounding box of a BMFace.
What I wanted to do in the first place was:
bm.faces[0].b_rect = [vmax,vmin,hmax,hmin]

Now with layers it looks a bit different:
bm.faces[0][b_rect] = "we will come to the bounding box later"
Note that the following will not work:
bm.faces[0]['b_rect'] = "something"

The layer needs to be accessed with the key generated by the face sequence as follows:
key = bm.faces.layers.int.new("b_rect")
bm.faces[0][key]  #read/write access

You can retrieve the key by typing:
key = bm.faces.layers.int['b_rect']

Now what Campbell suggested to my problem was storing my complex data in a list and adding the index of the data in that list to my face as an int layer:

MyData = []
MyData.append([vmax,vmin,hmax,hmin])
index = len(MyData)-1

bm.faces[0][b_rect] = index


I still hope that at some point I could extend the wrapper classes directly to store my data.


Best, Lukas