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 elements of
7 plus one dimension are additionally created. All created elements
8 can be automatically grouped. Extrusion can be used to create a
9 \ref extrusion_struct "structured mesh from scratch".
11 \image html extrusion_box.png "If you extruded e.g. several quadrangles, you get exactly same mesh as if you meshed a geometrical box (except that the initial quadrangles can be incorrectly oriented)"
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 common for node, segments and faces will appear:
37 \image html extrusionalongaline1.png
39 \image html extrusionalongaline2.png
41 \image html extrusionalongaline3.png
47 <li>Select the type of elements which will be extruded (nodes, 1D or
49 <li>Specify the IDs of the elements which will be extruded by one
52 <li><b>Select the whole mesh, sub-mesh or group</b> activating this
54 <li>Choose mesh elements with the mouse in the 3D Viewer. It is
55 possible to select a whole area with a mouse frame.</li>
56 <li>Input the element IDs directly in <b>ID Elements</b>
57 field. The selected elements will be highlighted in the viewer.</li>
58 <li>Apply Filters. <b>Set filter</b> button allows to apply a
59 filter to the selection of elements. See more about filters in
60 the \ref filtering_elements "Selection filters" page.</li>
63 <li>If the <b>Extrusion to Distance</b> radio button is selected</li>
65 <li>specify the translation vector by which the elements will be extruded.</li>
67 <li>If the <b>Extrusion Along Vector</b> radio button is selected</li>
69 <li>specify the coordinates of the \b Vector along which the elements
70 will be extruded, or select the face (the normal to the face will
71 define the vector),</li>
72 <li>specify the \b Distance of extrusion along the vector (it can
75 <li>If the <b>Extrusion By Normal</b> radio button is selected,
76 which is visible in \b 2D mode only, every node of selected
77 elements is extruded along the \a average of the \a normal vectors to
78 the faces sharing the node.</li>
80 <li>Specify the \b Distance of extrusion (it can be negative),</li>
81 <li>Use <b>Along average normal</b> check-box to specify along
82 what vector the distance is measured. If it is \a activated the
83 distance is measured along the average normal mentioned
84 above. If it is \a deactivated every node is extruded along the
85 average normal till its intersection with the virtual plane got
86 by translation of the face sharing the node along its own normal
88 The picture below shows a cross-section of a 2D mesh extruded
89 with <b>Along average normal</b> activated (to the left) and
90 deactivated (to the right).
92 \image html extrusionbynormal_alongavgnorm.png
94 <li>Using <b>Use only input elements</b> check-box to specify what
95 elements to use to compute the average normal. If it is \a
96 activated only selected faces, among faces sharing the node,
97 are used to compute the average normal at the node. Else all
98 faces sharing the node are used. <br>
99 The picture below shows a cross-section of a 2D mesh the upper
100 plane of which is extruded with <b>Use only input elements</b>
101 activated (to the left) and deactivated (to the right).
103 \image html extrusionbynormal_useonly.png
106 <li>Specify the <b>Number of steps</b>.</li>
107 <li>If you activate <b>Generate Groups</b> check-box, the <em>result elements</em>
108 created from <em>selected elements</em> contained in groups will be
109 included into new groups named by pattern "<old group
110 name>_extruded" and "<old group name>_top". For example if a
111 selected quadrangle is included in \a g_Faces group (see figures
112 below) then result hexahedra will be included in \a
113 g_Faces_extruded group and a quadrangle created at the "top" of
114 extruded mesh will be included in \a g_Faces_top group. <br>
115 \image html extrusion_groups.png
116 \image html extrusion_groups_res.png
117 <p> This check-box is active only if there are some groups in the mesh.
121 <li>Click \b Apply or <b> Apply and Close</b> button to confirm the operation.</li>
123 \anchor extrusion_struct
124 <h2>Example: creation of a structured mesh from scratch</h2>
126 \image html image75.jpg "A node is extruded into a line of segments"
128 \image html image76.jpg "The line of segments is extruded into a quadrangle mesh"
130 \image html image77.jpg "The quadrangle mesh is revolved into a hexahedral mesh"
133 <br><b>See Also</b> a sample TUI Script of an
134 \ref tui_extrusion "Extrusion" operation.