3 \page extrusion_page Extrusion
5 \n Extrusion is used to build mesh elements of plus one
6 dimension than the input ones. Boundary elements around generated
7 mesh of plus one dimension are additionally created. All created
8 elements can be automatically grouped. Extrusion can be used to create
9 a \ref extrusion_struct "structured mesh from scratch".
11 \image html extrusion_box.png "If you extrude several quadrangles, you get exactly the same mesh as if you meshed a geometrical box (except for that the initial quadrangles can be incorrectly oriented): quadrangles and segments are created on the boundary of the generated mesh"
13 <p>Any node, segment or 2D element can be extruded. Each type of
14 elements is extruded into a corresponding type of result elements:
16 <tr><td><b>Extruded element</b></td><td><b> Result element </b></td></tr>
17 <tr><td>Node </td><td> Segment </td></tr>
18 <tr><td>Segment </td><td> Quadrilateral </td></tr>
19 <tr><td>Triangle </td><td> Pentahedron </td></tr>
20 <tr><td>Quadrilateral </td><td> Hexahedron </td></tr>
21 <tr><td>Polygon </td><td> Polyhedron </td></tr>
22 <tr><td>Hexagonal polygon </td><td> Hexagonal prism </td></tr>
25 <em>To use extrusion:</em>
27 <li>From the \b Modification menu choose the \b Extrusion item or click
28 <em>"Extrusion"</em> button in the toolbar.
31 \image html image91.png
32 <em>"Extrusion" button</em>
35 The following dialog will appear:
37 \image html extrusionalongaline1.png
43 <li>Specify \b Nodes, \b Edges and \b Faces, which will be extruded, by one
46 <li><b>Select the whole mesh, sub-mesh or group</b> activating the
47 corresponding check-box.</li>
48 <li>Choose mesh elements with the mouse in the 3D Viewer. It is
49 possible to select a whole area with a mouse frame.</li>
50 <li>Input the element IDs directly in <b>Node IDs</b>, <b>Edge
51 IDs</b> and <b>Face IDs</b> fields. The selected elements will
52 be highlighted in the viewer, if the mesh is shown there.</li>
53 <li>Apply Filters. <b>Set filter</b> button allows to apply a
54 filter to the selection of elements. See more about filters in
55 the \ref filtering_elements "Selection filters" page.</li>
58 <li>If the <b>Extrusion to Distance</b> radio button is selected
59 - specify the translation vector by which the elements will be extruded.
63 \image html extrusionalongaline2.png
65 <li>If the <b>Extrusion Along Vector</b> radio button is selected
67 <li>specify the coordinates of the \b Vector along which the elements
68 will be extruded, either directly or by selecting the mesh face (the
69 normal to the face will define the vector),</li>
70 <li>specify the \b Distance of extrusion along the vector (it can
76 \image html extrusionalongaline3.png
78 <li>If the <b>Extrusion By Normal</b> radio button is selected,
79 every node of the selected faces is extruded along the \a average
80 of the \a normal vectors to the faces sharing the node. (Nodes and
81 edges cannot be extruded in this mode.)
83 <li>Specify the \b Distance of extrusion (it can be negative),</li>
84 <li>Use <b>Along average normal</b> check-box to specify along
85 which vector the distance is measured.
87 <li>If it is \a activated the distance is measured along the
88 average normal mentioned above. </li>
89 <li>If it is \a deactivated every node is extruded along the
90 average normal till its intersection with a virtual plane obtained
91 by translation of the face sharing the node along its own normal
92 by the \b Distance.</li>
94 The picture below shows a cross-section of a 2D mesh extruded
95 with <b>Along average normal</b> activated (to the left) and
96 deactivated (to the right).
98 \image html extrusionbynormal_alongavgnorm.png "'Along average normal' activated (to the left) and deactivated (to the right)"
101 <li><b>Use only input elements</b> check-box specifies what
102 elements will be used to compute the average normal.<ul>
103 <li> If it is \a activated only selected faces, among faces
104 sharing the node, are used to compute the average normal at
106 <li>Else all faces sharing the node are used.</li></ul>
108 The picture below shows a cross-section of a 2D mesh the upper
109 plane of which is extruded with <b>Use only input elements</b>
110 activated (to the left) and deactivated (to the right).
112 \image html extrusionbynormal_useonly.png "'Use only input elements' activated (to the left) and deactivated (to the right)"
117 <li>Specify the <b>Number of steps</b>.</li>
118 <li>If you activate <b>Generate Groups</b> check-box, the <em>result elements</em>
119 created from <em>selected elements</em> contained in groups will be
120 included into new groups named by pattern "<old group
121 name>_extruded" and "<old group name>_top". For example if a
122 selected quadrangle is included in \a g_Faces group (see figures
123 below) then result hexahedra will be included in \a
124 g_Faces_extruded group and a quadrangle created at the "top" of
125 extruded mesh will be included in \a g_Faces_top group. <br>
126 \image html extrusion_groups.png
127 \image html extrusion_groups_res.png
128 <p> This check-box is active only if there are some groups in the mesh.
132 <li>Click \b Apply or <b> Apply and Close</b> button to confirm the operation.</li>
136 \anchor extrusion_struct
137 <h2>Example: creation of a structured mesh from scratch</h2>
139 \image html image75.jpg "A node is extruded into a line of segments"
141 \image html image76.jpg "The line of segments is extruded into a quadrangle mesh"
143 \image html image77.jpg "The quadrangle mesh is revolved into a hexahedral mesh"
146 <br><b>See Also</b> a sample TUI Script of an
147 \ref tui_extrusion "Extrusion" operation.