/*! \page symmetry_page Symmetry \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" One of the following dialogs will appear: 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)" </li> <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> <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>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>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>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> </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> </ol> <br><b>See Also</b> a sample TUI Script of a \ref tui_symmetry "Symmetry" operation. */