/*!

\page creating_groups_page Creating groups

\n In MESH you can create groups of elements of a certain type whose
contents is defined in different ways. To create a group, in the \b
Mesh menu select <b>Create Group</b> item (also available in the
contextual menu of the mesh).<br> 
To create a group of any type you should define the following: 
<ul>
<li><b>Mesh</b> - 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>
<li><b>Color</b> - allows to assign to the group a certain color, for
example, defining boundary conditions. The chosen color is used to
display the elements of the group. The color attribute of the group is
not persistent, it is lost if you save and then load the study from
the file.</li>
</ul>
SALOME Platform distinguishes between the three Group types:
<b>Standalone Group</b>, <b>Group on Geometry</b> and <b>Group on Filter</b>.

\anchor standalone_group <br><h2>"Standalone Group"</h2>

<b>Standalone Group</b> contains a list of mesh elements, which you can define in
the following ways:
<ul>
<li>By adding all entities of the chosen type existing in the
  mesh. For this, turn on the <b>Select All</b> check box. In this mode
  all controls, which allow selecting the entities in other ways are
  disabled.</li>
<li>By applying the Filter. The <b>Set filter</b> button allows to
  define the filter for selection of the elements for your group. See more
  about filters on the 
  \ref selection_filter_library_page "Selection filter library" page.<br>
  If the <b>Enable manual edition</b> check box is turned off, the defined
  filter defines contents of the group. In this mode, the filter is
  applied to all elements of the mesh. If none entity satisfies the
  filter, the \b Apply button is disabled.<br>
  If the <b>Enable manual edition</b> check box is turned on, the defined
  filter can be used to for selection of entities composing the group.</li>
<li>By choosing entities manually with the mouse in the 3D Viewer. For
  this, turn on the <b>Enable manual edition</b> check box. 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>By adding entities from either a submesh or an existing
  group.  For this, turn on the <b>Enable manual edition</b> check
  box. <b>Select from</b> set of fields allows to select a submesh or
  a group of an appropriate type.</li>
</ul>
In the <b>manual edition</b> mode you can
<ul>
<li>click the \b Remove button to remove selected elements from the list</li>
<li>click the <b>Sort List</b> button to sort the list of IDs of 
mesh elements.</li>
</ul>

\image html creategroup.png


For example, to create a new group containing all faces of an
existing group and some other faces selected in the viewer:
<ul>
<li> Select the \b Face type of entities and input the name of the new group.</li>
<li> Check the \b Group checkbox in <b>Select From</b> group.</li>
<li> Select the existing group of faces in the object browser or in the viewer</li>
<li> Click \b Add in \b Content group. <b>Id Elements</b> list will be filled
with IDs of faces belonging to the exising group.</li>
<li> Select other faces in the viewer.</li>
<li> Click \b Add in \b Content group.</li>
<li> Click \b Apply button to create the new group.</li>
</ul>

Please note that the new group does not have references to the source
group. It contains only the list of face IDs. So if the source group
is changed, the new one is not updated accordingly.


\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.  


\anchor group_on_geom <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. The group on geometry contains the elements
of a certain type generated on the selected geometrical object. Group
contents is dynamically updated if the mesh is modified.<br>
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

\image html image132.gif
<center>In this picture the cells which belong to a certain
  geometrical 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.



\anchor group_on_filter <br><h2>"Group on Filter"</h2>

To create a group on filter check <b>Group on filter</b> in the <b>
Group type</b> field. The group on filter contains the elements
of a certain type satisfying the defined filter. Group contents is
dynamically updated if the mesh is modified.<br> To define a group,
click the <b>Set filter</b> button and define criteria of the
filter in the opened dialog. After confirmation of the operation a
new group of mesh elements will be created. See more about filters on
the \ref selection_filter_library_page "Selection filter library" page.

\image html creategroup_on_filter.png

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

*/