\n This geometrical operation allows to perform a symmetrical copy of
your mesh or some of its elements.
+<em>To create a symmetrical copy:</em>
+
+<ol>
+<li>From the \b Modification menu choose \b Transformation -> \b Symmetry item or click
+<em>"Symmetry"</em> button in the toolbar.
+
\image html symmetry.png "Symmetry button"
-<em>To apply symmetry to your mesh:</em>
-\par
-From the \b Modification choose \b Transformation and from its
-sub-menu select the \b Symmetry item. The following dialog box shall
-appear:
+One of the following dialogs will appear:
-\image html symmetry1.png
+It is possible to mirror a mesh or some of its elements through:
+\image html symmetry1.png "a point" <br>
+\image html symmetry2.png "an axis" <br>
+\image html symmetry3.png "a plane (defined by a point and a normal to the plane)"
-\image html symmetry2.png
+</li>
-\image html symmetry3.png
+<li>In the dialog:
+<ul>
+<li>specify the elements for the symmetry operation:
+
+<ul>
+<li><b>Select the whole mesh, submesh or group</b> activating this
+checkbox; or</li>
+<li>choose mesh elements with the mouse in the 3D Viewer. It is
+possible to select a whole area with a mouse frame; or</li>
+<li>input the element IDs directly in <b>ID Elements</b> field. The
+ selected elements will be highlighted in the viewer; or</li>
+<li>apply Filters. <b>Set Filter</b> button allows to apply a
+ \ref filtering_elements "filter" to the selection of elements.</li>
+</ul>
+</li>
-\par
-This operation has three options, you can symmetrically copy your mesh
-or some of its elements specifying:
+<li>depending on the nature of the mirror object:
+<ul>
+<li>if the mesh is mirrored through a point, specify the coordinates
+ of the point, either directly or by picking a mesh node;</li>
+<li>if the mesh is mirrored through an axis:
<ul>
-<li>one point</li>
-<li>one axis (point and vector)</li>
-<li>one plane (point and normal)</li>
+<li>specify the coordinates of the start \b Point of the axis, either
+ directly or by picking a mesh node;</li>
+<li>specify the components of axis \b Vector, either directly or by
+ picking a mesh node, in which case \b Vector is defined as a shift
+ between the \b Point and the node;</li>
</ul>
+</li>
+<li>if the mesh is mirrored through a plane:
<ul>
-<li>Select elements for the symmetry operation
+<li>specify the cooordinates of the \b Point lying on the plane,
+ either directly or by picking a mesh node;</li>
+<li>specify the components of plane \b Normal, either directly or by
+ picking a mesh node, in which case \b Normal is defined as a shift
+ between the \b Point and the node.</li>
+</ul>
+</li>
+
+<li>specify the conditions of symmetry operation:
<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>
+<li>activate <b>Move elements</b> radio button to change the location of
+ the selected elements within the current mesh;</li>
+<li>activate <b>Copy elements</b> radio button to duplicate the
+ selected elements at the new location within the current mesh;</li>
+<li>activate <b>Create as new mesh</b> radio button to create a new
+ element in a new mesh; the new mesh appears in the Object Browser
+ with the default name \a MeshName_mirrored (it is possible to change
+ this name in the adjacent box);</li>
+<li>activate <b> Copy groups </b> check-box to put new mesh entities
+ into new groups if source entities belong to some groups. New
+ groups are named by pattern "<old group name>_mirrored".</li>
</ul>
</li>
-<li>When <b>Move elements</b> radio button is selected, the source mesh (or elements) is created at the new location and erased from its previous location</li>
-<li>When <b>Copy elements</b> radio button is selected,the source mesh (or elements) is created at the new location, but it also remains at its previous location and is considered one and single mesh with the result of the translation.</li>
-<li>When <b>Create as new mesh</b> radio button is selected, the source mesh (or elements) remains at its previous location and a new mesh is created at the new location and appears in the Object Browser with the default name MeshName_mirrored (you can change this name in the adjacent box).</li>
-<li><b> Copy groups </b> checkbox allows copying the groups of elements of the source mesh to the newly created one.</li>
+</ul>
+<li>activate <b>Preview</b> check-box to show the result of
+ transformation in the viewer;</li>
+<li>click \b Apply or <b> Apply and Close</b> button to confirm the
+ operation.</li>
</ul>
-\par
+</ol>
<br><b>See Also</b> a sample TUI Script of a
\ref tui_symmetry "Symmetry" operation.
