/*!

\page creating_groups_page Creating groups

\n In MESH you can create groups of elements of different types. To
create a group of elements in the \b Mesh menu select <b>Create
Group</b>.
\n To create any group you should define the following:
<ul>
<li><b>Mesh</b> - the name of the mesh whose elements will form your
group. You can select your mesh in the Objet Browser or in the 3D
viewer.</li>
<li><b>Elements Type</b> - set of radio buttons allows to select the type of
elements which will form your group:</li>
<ul>
<li><b>Nodes</b></li>
<li><b>Edges</b></li>
<li><b>Faces</b></li>
<li><b>Volumes</b></li>
</ul>
<li><b>Name</b> field allows to enter the name of your new group.</li>
</ul>
SALOME Platform distinguishes between the two Group types:
<b>Standalone Group</b> and <b>Group on Geometry</b>.

<br><h2>Standalone Group</h2>

<b>Standalone Group</b> consists of mesh elements, which you can define in
two possible ways.
<ul>
<li>Choosing them manually with the mouse in the 3D Viewer. You can
click on an element in the 3D viewer and it will be highlighted. After
that click the \b Add button and the ID of this element will be added to
the list.</li>
<li>Applying Filters. The <b>Set filter</b> button allows to apply a
definite filter to selection of the elements of your group. See more
about filters on the
\ref selection_filter_library_page "Selection filter library" page.</li>
</ul>
To remove a selected element or elements from the list click the
\b Remove button. The <b>Sort List</b> button allows to sort the list of IDs of
mesh elements.
\n <b>Select from</b> set of fields allows to choose a submesh or an existing
group whose elements of the previously defined type will be added to
the list of elements which will form your group.
\n <b>Color</b> - allows to assign to the group a certain color, for
example, defining boundary conditions. This feature introduces a
useful element of preprocessing in Mesh module. Note that <b>Color</b> attribute defines
the colors used for the display of the elements of the group. 
\n <b>Warning</b> The Med Color group interface may change in future versions of Salome.


\image html creategroup.png

\image html image130.gif
<center>In this picture the brown cells belong to a group defined manually.</center>

\image html image131.gif
<center>In this picture the brown cells belong to the group defined by the criterion 
<b>Taper > 0</b>.</center>

<b>See Also</b> a sample TUI Script of a 
\ref tui_create_standalone_group "Create a Standalone Group"
operation.  

<br><h2>Group on Geometry</h2>

To create a group on geometry check <b>Group on geometry</b> in the \b Group
\b type field. <b>Group on geometry</b> contains the elements of a certain type
belonging to the selected geometrical object. To define a group select
in the Objet Browser or in the 3D viewer a geometrical object from
which the elements will be taken. After confirmation of the operation
a new group of mesh elements will be created.

\image html a-creategroup.png

<br><br>
To create multiple groups on geometry of both nodes and elements of
any type at once, in the \b Mesh menu select <b>Create Groups from
Geometry</b>.<br>
Group names are same as those of geometrical objects.
Type of group of mesh elements is defined automatically by 
<b>Geometrical object</b> nature.

\image html create_groups_from_geometry.png

\image html image132.gif
<center>In this picture the cells which belong to a certain face are
selected in green.</center>

<b>See Also</b> a sample TUI Script of a 
\ref tui_create_group_on_geometry "Create a Group on Geometry"
operation.

<br><h2>Creation of groups using existing groups and sub-meshes.</h2>

Application provides possibility to create new <b>standalone</b> groups using existing standalone groups, groups on geometry and sub-meshes. This functionality is implemented using "Select from" group box of "Create group" dialog box described above.

This functionality is described on the example of creating new group   from existing standalone groups and groups on geometry.

Imagine there are group G1. It can be standalone group or group on geometry.

To create group G2 containing all entities of group G1 and a faces graphically selected in 3D view following steps can be performed:
<ul>
<li>User opens "Create group" dialog box.</li>
<li>The user specifies "Face" type of entities and "G2" name of group.</li>
<li>The user checks "Group" check-box of "Select From" group box.</li>
<li>The user selects G1 group in object browser or 3D view.</li>
<li>The user presses "Add" push button of "Content" group box. "Id Elements" list-box is filled with identifiers of faces belonging to group G1.</li>
<li>The user selects other faces in 3D view.</li>
<li>The user presses "Apply" button. System creates group G2.</li>
</ul>

Please note that group G2 does not have a references to source group G1. It contains list of faces identifiers only. So if G1 group will be changed group G2 will remain unmodified.

<br>
\anchor gui_create_dim_group
<h2>Creating groups of entities from existing groups of superior dimensions</h2>

Application provides possibility for creating groups of entities from existing groups of superior dimensions. For example, it is possible to create group of nodes using list of existing groups of faces.

To create groups of entities from existing groups of superior dimensions, in the \b Mesh menu select <b>Group of underlying entities</b>.<br>

The following dialog box will appear:

\image html dimgroup_dlg.png

In this dialog box you should specify the name of the resulting group, types of entities and set of source groups.

For example, we have two source Volume groups illustrated on the figure below 

\image html dimgroup_src.png
<center>Source groups</center>

In this case we obtain following results for Faces, Edges and Nodes.

\image html dimgroup_2d.png
<center>Faces</center>

\image html dimgroup_1d.png
<center>Edges</center>

\image html dimgroup_0d.png
<center>Nodes</center>

<b>See Also</b> a sample TUI Script of a 
\ref tui_create_dim_group "Creating groups of entities from existing groups of superior dimensions"
operation.
*/