/*!

\page reorient_faces_page Reorient faces by vector

\n This operation allows changing orientation of a set of neighboring
faces. The desired orientation is defined by a vector. Since the direction
of face normals in the set can be even opposite, it is necessary to
specify a control face whose normal will be compared with the vector. This
face can be either specified explicitly or found by proximity to
a given point.

Orientation of a face is changed by reverting the order of its nodes.

<em>To change orientation of faces:</em>
<ol>
<li>In the \b Modification menu select <b>Reorient faces by
    vector</b> item or click <em>Reorient faces by
    vector</em> button in the toolbar.

<center>
\image html reorient_faces_face.png
<em>"Reorient faces by vector" button</em>
</center>

The following dialog box will appear:

<center>
\image html reorient_2d_point.png
\image html reorient_2d_face.png
</center>

<li>In this dialog
<ul>
<li>Specify the way of selection of the control face: by point or
  explicitly.</li>
<li>Select the \b Object (mesh, sub-mesh or a group of faces) containing faces to reorient in the Object Browser or in the 3D Viewer.</li>
<li>Specify the coordinates of the \b Point by which the control face
  will be found or of the control \b Face itself. You can easy specify the \b
  Point by either picking a node in the 3D Viewer or selecting a vertex
  in the Object Browser. It is possible to pick the  \b Face by mouse in
  the 3D Viewer or enter its ID.</li>
<li>Set up the \b Direction vector to be compared with the normal of the
  control face. If you pick a node in the 3D Viewer then the \b Direction
  vector will go from the coordinate system origin to the selected node.
  If you pick two nodes (holding Shift button) then the \b Direction vector
  will go from the first to the second node.</li>
</ul>
</li>

<li>Click the \b Apply or <b>Apply and Close</b> button to confirm the operation.</li>
</ol>

<br><b>See Also</b> a sample TUI Script of a
\ref tui_reorient_faces "Reorient faces by vector" operation. 

*/