/*!

\page revolution_page Revolution

\n Revolution is a type of surface meshing by generation from
discretized lines. It is used to build mesh elements of plus one
dimension than the swept ones. Each swept 1D element produces one or
more quadrangles (or triangles if one node of a rotated element lays
on the revolution axis).

<em>To apply revolution:</em>
<ol>
<li>From the \b Modification menu choose the \b Revolution item or click
<em>"Revolution"</em> button in the toolbar.

\image html image92.png
<center><em>"Revolution" button</em></center>

The following dialog box shall appear:

\image html revolution1.png

\image html revolution2.png
</li>

<li>
In this dialog box you should specify:
<ul>
<li>the type of elements which will be extruded (1D or 2D),</li>
<li>specify the IDs of the elements which will be revolved
<ul>
<li>Check on <b>Select the whole mesh, submesh or group</b> option
<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</li>
<li>Applying Filters. The <b>Set filter</b> button allows to apply a
definite filter to selection of the elements. See more
about filters on the
\ref selection_filter_library_page "Selection filter library" page.</li>
</ul>
</li>
<li>specify the axis (point and vector) around which the elements will
be revolved,</li>
<li>angle of rotation and number of steps,</li>
<ul> <li> Angle by Step - the elements are extruded by the specified angle at each step (i.e. for Angle=30 and Number of Steps=2, the elements will be extruded 
 by 30 degrees twice for a total of 30*2=60)</li>

\image html revolutionsn2.png "Example of Revolution with Angle by Step"

<li> Total Angle - the elements are extruded by the specified angle only once and the number of steps defines the number of iterations 
(i.e.for Angle=30 and Number of Steps=2, the elements will be extruded by 30/2=15 degrees twice for a total of 30). </li>

\image html revolutionsn1.png "Example of Revolution with Total Angle"

</ul>
<li>tolerance of rotation</li>
</ul>

<li> <b>Preview</b> checkbox allows showing the results of parameter-setting in the viewer </li>
<li> <b>Generate Groups</b> checkbox allows copying the groups of
elements of the source mesh to the newly created one. </li>
</li>

<li>Click the \b Apply or \b OK button.</li>
</ol>


<br><b>See Also</b> a sample TUI Script of a 
\ref tui_revolution "Revolution" operation.

*/