3 \page grouping_elements_page Grouping elements
5 In Mesh module it is possible to create groups of mesh entities:
6 nodes, edges, faces, volumes, 0D elements or balls. One group contains
7 elements of only one type. Groups, unlike sub-meshes, are exported
8 along with mesh entities into the files of following formats: MED, UNV,
9 and CGNS. The group has a color attribute which is used for
10 visualization only and is not exported.
12 There are three types of groups different by their internal
14 <li><b>Standalone group</b> is a static set of mesh entities. Its
15 contents can be explicitely controlled by the user. Upon removal of
16 the entities included into the group, the group becomes empty and
17 the user is to pay efforts to restore its contents. Hence it is
18 resonable to create standalone groups when the mesh generation is
19 finished and mesh quality is verified.
20 \warning Creation and edition of large standalone groups in
21 \ref creating_groups_page "Create group" dialog using manual edition
22 is problematic due to poor performance of the dialog.</li>
23 <li><b>Group on geomerty</b> is associated to one or a group of
24 sub-shapes of the main shape and includes mesh entities generated on
25 this geometrical entities. The association to geometry is
26 established at group construction and can't be changed. The group
27 contents is always up-to-date without user's efforts, hence the
28 group can be created even before mesh elements generation.</li>
29 <li><b>Group on filter</b> encapsulates a filter which is used to
30 select mesh entities composing the group from the whole
31 mesh. Criteria of the filter can be changed at any time. The
32 group contents is always up-to-date without user's efforts, hence
33 the group can be created even before mesh elements generation.</li>
35 The group on geometry and group on filter can be converted to
38 \image html groups_in_OB.png "Groups of different types look differently in the Object Browser"
40 The following ways of group creation are possible:
42 - \subpage creating_groups_page "Create group" dialog allows creation of
43 a group of any of all the three types:
44 \ref standalone_group "Standalone group",
45 \ref group_on_geom "Group on geometry" and
46 \ref group_on_filter "Group on filter" using dedicated tabs.
47 - \subpage create_groups_from_geometry_page "Create Groups from Geometry"
48 dialog allows creation of several groups on geometry at once.
49 - Standalone groups of all nodes and elements of the chosen sub-mesh
50 (type of elements depends on dimension of sub-mesh geometry) can
51 be created using <b>Mesh -> Construct Group</b> menu item (available
52 in context menu as well).
53 - Standalone groups of any element type can be created basing on nodes
54 of other groups - using \subpage group_of_underlying_elements_page
55 "Group based on nodes of other groups" dialog.
56 - Standalone groups can be created by applying
57 \subpage using_operations_on_groups_page "Boolean operations" to
59 - Creation of standalone groups is an option of many
60 \ref modifying_meshes_page "mesh modification" operations.
62 The created groups can be later:
64 - \subpage editing_groups_page "Edited"
65 - \subpage deleting_groups_page "Deleted", either as an object or
66 together with contained elements.
67 - The group on geometry and group on filter can be
68 \ref convert_to_standalone "converted into the standalone" group.
69 - \ref importing_exporting_meshes_page "Exported" into a file as a
72 In the Object Browser, if groups container item includes more
73 than one group, it is possible to sort the groups by name in
74 ascending order. For this, select the groups container in the Object
75 Browser and choose <b>Sort children</b> context menu item.
77 \image html smesh_sort_groups.png "Sorting groups"
79 An important tool, providing filters for creation of standalone
80 groups and groups on filter is \ref selection_filter_library_page.
