mesh_edit.py

import bpy, bmesh

def bmesh_join(list_of_bmeshes, list_of_matrices, normal_update=False):
    # sourcery skip: use-contextlib-suppress
    """ takes as input a list of bm references and outputs a single merged bmesh
    allows an additional 'normal_update=True' to force _normal_ calculations.
    """
    bm = bmesh.new()
    add_vert = bm.verts.new
    add_face = bm.faces.new
    add_edge = bm.edges.new

    for bm_to_add, matrix in zip(list_of_bmeshes, list_of_matrices):
        bm_to_add.transform(matrix)

    for bm_to_add in list_of_bmeshes:
        offset = len(bm.verts)

        for v in bm_to_add.verts:
            add_vert(v.co)

        bm.verts.index_update()
        bm.verts.ensure_lookup_table()

        if bm_to_add.faces:
            for face in bm_to_add.faces:
                add_face(tuple(bm.verts[i.index + offset] for i in face.verts))
            bm.faces.index_update()

        if bm_to_add.edges:
            for edge in bm_to_add.edges:
                edge_seq = tuple(bm.verts[i.index + offset]
                                 for i in edge.verts)
                try:
                    add_edge(edge_seq)
                except ValueError:
                    # edge exists!
                    pass
            bm.edges.index_update()

    if normal_update:
        bm.normal_update()

    me = bpy.data.meshes.new("joined_mesh")
    bm.to_mesh(me)

    return me