export_3ds.py

        bpy.ops.object.mode_set(mode='OBJECT')

    # Initialize the main chunk (primary):
    primary = _3ds_chunk(PRIMARY)
    # Add version chunk:
    version_chunk = _3ds_chunk(VERSION)
    version_chunk.add_variable("version", _3ds_uint(3))
    primary.add_subchunk(version_chunk)

    # init main object info chunk:
    object_info = _3ds_chunk(OBJECTINFO)

    ''' # COMMENTED OUT FOR 2.42 RELEASE!! CRASHES 3DS MAX
    # init main key frame data chunk:
    kfdata = make_kfdata()
    '''

    # Make a list of all materials used in the selected meshes (use a dictionary,
    # each material is added once):
    materialDict = {}
    mesh_objects = []

    scene = context.scene

    if use_selection:
        objects = (ob for ob in scene.objects if ob.is_visible(scene) and ob.select)
    else:
        objects = (ob for ob in scene.objects if ob.is_visible(scene))

    for ob in objects:
        # get derived objects
        free, derived = create_derived_objects(scene, ob)

        if derived is None:
            continue

        for ob_derived, mat in derived:
            if ob.type not in {'MESH', 'CURVE', 'SURFACE', 'FONT', 'META'}:
                continue

            try:
                data = ob_derived.to_mesh(scene, True, 'PREVIEW')
            except:
                data = None

            if data:
                matrix = global_matrix * mat
                data.transform(matrix)
                mesh_objects.append((ob_derived, data, matrix))
                mat_ls = data.materials
                mat_ls_len = len(mat_ls)

                # get material/image tuples.
                if data.tessface_uv_textures:
                    if not mat_ls:
                        mat = mat_name = None

                    for f, uf in zip(data.tessfaces, data.tessface_uv_textures.active.data):
                        if mat_ls:
                            mat_index = f.material_index
                            if mat_index >= mat_ls_len:
                                mat_index = f.mat = 0
                            mat = mat_ls[mat_index]
                            mat_name = None if mat is None else mat.name
                        # else there already set to none

                        img = uf.image
                        img_name = None if img is None else img.name

                        materialDict.setdefault((mat_name, img_name), (mat, img))

                else:
                    for mat in mat_ls:
                        if mat:  # material may be None so check its not.
                            materialDict.setdefault((mat.name, None), (mat, None))

                    # Why 0 Why!
                    for f in data.tessfaces:
                        if f.material_index >= mat_ls_len:
                            f.material_index = 0

        if free:
            free_derived_objects(ob)

    # Make material chunks for all materials used in the meshes:
    for mat_and_image in materialDict.values():
        object_info.add_subchunk(make_material_chunk(mat_and_image[0], mat_and_image[1]))

    # Give all objects a unique ID and build a dictionary from object name to object id:
    """
    name_to_id = {}
    for ob, data in mesh_objects:
        name_to_id[ob.name]= len(name_to_id)
    #for ob in empty_objects:
    #    name_to_id[ob.name]= len(name_to_id)
    """

    # Create object chunks for all meshes:
    i = 0
    for ob, blender_mesh, matrix in mesh_objects:
        # create a new object chunk
        object_chunk = _3ds_chunk(OBJECT)

        # set the object name
        object_chunk.add_variable("name", _3ds_string(sane_name(ob.name)))

        # make a mesh chunk out of the mesh:
        object_chunk.add_subchunk(make_mesh_chunk(blender_mesh, matrix, materialDict))

        # ensure the mesh has no over sized arrays
        # skip ones that do!, otherwise we cant write since the array size wont
        # fit into USHORT.
        if object_chunk.validate():
            object_info.add_subchunk(object_chunk)
        else:
            operator.report({'WARNING'}, "Object %r can't be written into a 3DS file")

        ''' # COMMENTED OUT FOR 2.42 RELEASE!! CRASHES 3DS MAX
        # make a kf object node for the object:
        kfdata.add_subchunk(make_kf_obj_node(ob, name_to_id))
        '''

        if not blender_mesh.users:
            bpy.data.meshes.remove(blender_mesh)
        #blender_mesh.vertices = None

        i += i

    # Create chunks for all empties:
    ''' # COMMENTED OUT FOR 2.42 RELEASE!! CRASHES 3DS MAX
    for ob in empty_objects:
        # Empties only require a kf object node:
        kfdata.add_subchunk(make_kf_obj_node(ob, name_to_id))
        pass
    '''

    # Add main object info chunk to primary chunk:
    primary.add_subchunk(object_info)

    ''' # COMMENTED OUT FOR 2.42 RELEASE!! CRASHES 3DS MAX
    # Add main keyframe data chunk to primary chunk:
    primary.add_subchunk(kfdata)
    '''

    # At this point, the chunk hierarchy is completely built.

    # Check the size:
    primary.get_size()
    # Open the file for writing:
    file = open(filepath, 'wb')

    # Recursively write the chunks to file:
    primary.write(file)

    # Close the file:
    file.close()

    # Clear name mapping vars, could make locals too
    del name_unique[:]
    name_mapping.clear()

    # Debugging only: report the exporting time:
    #Blender.Window.WaitCursor(0)
    print("3ds export time: %.2f" % (time.clock() - time1))

    # Debugging only: dump the chunk hierarchy:
    #primary.dump()

    return {'FINISHED'}