create Bmesh
python - June 15, 2017 - 14:51creer un bmesh à partir d''un mesh existant
me = ob.data
if me.is_editmode:
bm = bmesh.from_edit_mesh(me)
else: # Create a bmesh from mesh
# (won''''t affect mesh, unless explicitly written back)
bm = bmesh.new()
bm.from_mesh(me)