\n In principle, <b>Extrusion along a path</b> works in the same way
as \b Extrusion, the main difference is that we define not a vector,
-but a path of extrusion which must be a meshed edge. To get an idea of
-how this algorithm works, examine several examples, starting from the
-most simple case of extrusion along a straight edge. In all examples
-the same mesh will be extruded along different paths and with
-different parameters. This sample 2D mesh has two quadrangle faces and
-seven edges. Look at the picture, where white digits are the node
-numbers and green are the element numbers:
+but a path of extrusion which must be a 1D mesh or 1D sub-mesh. To
+get an idea of how this algorithm works, examine several examples,
+starting from the most simple case of extrusion along a straight edge.
+In following examples the meshes will be extruded along different
+paths and with different parameters.
+This sample 2D mesh has two quadrangle faces and seven edges. Look
+at the picture, where white digits are the node numbers and green
+are the element numbers:
\image html mesh_for_extr_along_path.png
\image html curvi_angles_after.png
<center>The same, but using angles {45, 45, 45, 0, -45, -45, -45}</center>
-<br><center><h2>Extrusion along a sub-mesh</h2></center>
+<br><center><h2>Extrusion of 2d face along a mesh builds on wire</h2></center>
-In this example the path mesh has been built on a wire (polyline with
-six edges). The first edge of the wire was used as <b>Shape (edge)</b>, node
-#1 as <b>Start node</b>. The angles have been defined as {10, 10, 10}. The
-middle edge (#4) of the initial mesh has been extruded.
+In this example the path mesh has been built on a wire contains 3
+edges. Node #1 is used as start node. Linear angle variation by 180
+degree is applied.
-\image html edge_wire_before.png
+\image html extr_along_wire_before.png
-\image html edge_wire_after.png
-
-<br><center><h2>Extrusion of 2d elements along a sub-mesh</h2></center>
-
-This extrusion bases on the same path mesh as in the previous example
-but the third edge of the wire was set as <b>Shape (edge)</b> and node
-#4 as <b>Start node</b>. Please note, that the extrusion has been done
-in direction from node #4 to node #3, i.e. against the wire
-direction. In this example both faces of the initial mesh have been
-extruded.
-
-\image html edge_wire_3d_before.png
-
-\image html edge_wire_3d_after.png
+\image html extr_along_wire_after.png
<br><center><h2>Extrusion of 2d elements along a closed path</h2></center>
<li>From the \b Modification menu choose the <b>Extrusion along a
path</b> item or click <em>"Extrusion along a path"</em> button in the toolbar.
-\image html image101.gif
+\image html image101.png
<center><em>"Extrusion along a path" button</em></center>
-The following dialog box will appear:
+The following dialog common for line and planar elements will appear:
\image html extrusion1.png
-
-\image html extrusion2.png
</li>
-<li>In the dialog box you should:
+<li>In this dialog:
<ul>
<li>select the type of elements which will be extruded (1D or 2D),</li>
-<li>specify the <b>IDs of the elements</b> which will be extruded by
-selecting them in the 3D viewer or <b>Select the whole mesh, submesh
-or group</b>,
+<li>specify the <b>IDs of the elements</b> which will be extruded
+
+<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 filter to the selection of elements. See more
+about filters in the \ref selection_filter_library_page "Selection filter library" page.</li>
+</ul>
+
</li>
<li>define the Path along which the elements will be extruded,
\n Path definition consists of several elements:
<ul>
-<li>\b Mesh - containing a 1D sub-mesh on the edge, along which proceeds the extrusion</li>
-<li><b>Shape (edge)</b> - as the mesh can be complex, the edge is used to define the sub-mesh for the path</li>
-<li><b>Start node</b> - the first or the last node on the edge. It is used to define the direction of extrusion </li>
+<li><b>Mesh or submesh</b> - 1D mesh or 1D sub-mesh, along which proceeds the extrusion</li>
+<li><b>Start node</b> - the start node. It is used to define the direction of extrusion </li>
</ul>
</li>
-<li> <b>Generate Groups</b> checkbox allows copying the groups of
+<li>activate <b>Generate Groups</b> checkbox if it is necessary to copy the groups of
elements of the source mesh to the newly created one. </li>
</ul>
</li>
right, add them to the list of angles at the left by pressing the <em>"Add"</em>
button and remove them from the list by pressing the <em>"Remove"</em> button.
-\image html image105.gif
+\image html add.png
<center><em>"Add" button</em></center>
-\image html image106.gif
+\image html remove.png
<center><em>"Remove" button</em></center>
+<b>Linear variation of the angles</b> option allows defining the angle of gradual rotation for the whole path.
+At each step the shape will be rotated by angle/nb. of steps.
+
</li>
</ul>
</li>
-<li>Click the \b Apply or \b OK button. Mesh edges will be extruded into
+
+<li>Click \b Apply or <b> Apply and Close</b> button to confirm the operation.
+Mesh edges will be extruded into
faces, faces into volumes. The external surface of the resulting 3d
mesh (if faces have been extruded) is covered with faces, and corners
with edges. If the path is closed, the resulting mesh can contain
<br><b>See Also</b> a sample TUI Script of an
\ref tui_extrusion_along_path "Extrusion along a Path" operation.
-*/
\ No newline at end of file
+*/
