3 \page extrusion_along_path_page Extrusion along Path
5 \n In principle, <b>Extrusion along Path</b> works in the same way
6 as \ref extrusion_page "Extrusion", the main difference is that we
7 define not a vector, but a path of extrusion which must be an 1D mesh
9 To get an idea of how this algorithm works, examine several examples,
10 starting from the most simple case of extrusion along a straight edge.
11 In the examples the sample mesh will be extruded along different
12 paths and with different parameters.
13 This 2D mesh has two quadrangle faces and seven edges. Look
14 at the picture, where white digits are the node numbers and green
15 are the element numbers:
17 \image html mesh_for_extr_along_path.png
19 <br><center><h2>Extrusion along a straight edge</h2>(not using base point
22 \image html straight_before.png
23 <center>The image shows a 1D path mesh, built on a linear edge, and the initial 2D mesh.</center>
25 \image html straight_after.png
26 <center> The image shows the result of extrusion of two edges
27 (#1 and #2) of the initial mesh along the path. \n Node #1 of path mesh
28 has been selected as Start node.</center>
30 <br><center><h2>Extrusion along a curvilinear edge</h2>(with and
31 without angles)</center>
33 \image html curvi_simple_before.png
34 <center>The image shows a 1D path mesh, built on curvilinear edge, and
35 the initial 2D mesh.</center>
37 \image html curvi_simple_after.png
38 <center>The central image shows the result of extrusion of one edge
39 (#2) of the initial mesh along the path. \n Node #1 of path mesh has
40 been selected as <b>Start node</b>.</center>
42 \image html curvi_angles_after.png
43 <center>The same, but using angles {45, 45, 45, 0, -45, -45, -45}</center>
45 <br><center><h2>Extrusion of a 2D face along a mesh built on a wire</h2></center>
47 In this example the path mesh has been built on a wire containing 3
48 edges. Node 1 is a start node. Linear angle variation by 180 degrees
49 has also been applied.
51 \image html extr_along_wire_before.png
52 <center><em>Meshed wire</em></center>
54 \image html extr_along_wire_after.png
55 <center><em>The resulting extrusion</em></center>
57 <br><center><h2>Extrusion of 2d elements along a closed path</h2></center>
59 \image html circle_simple_before.png
60 <center>The image shows a path mesh built on a closed edge
63 \image html circle_simple_after.png
64 <center>The central image shows the result of extrusion of both faces
65 of the initial mesh. \n Note, that no sewing has been done, so, there are
66 six coincident nodes and two coincident faces in the resulting
69 \image html circle_angles_after.png
70 <center>The same, but using angles {45, -45, 45, -45, 45, -45, 45, -45}
73 <br><em>To use Extrusion along Path:</em>
75 <li>From the \b Modification menu choose the <b>Extrusion along a
76 path</b> item or click <em>"Extrusion along a path"</em> button in the toolbar.
78 \image html image101.png
79 <center><em>"Extrusion along a path" button</em></center>
81 The following dialog will appear:
83 \image html extrusion_along_path_dlg.png
88 <li>Use \a Selection button to specify what you are going to
89 select at a given moment, \b Nodes, \b Edges or \b Faces.
90 \image html image120.png
91 <center><em>"Selection" button</em></center>
93 <li>Specify \b Nodes, \b Edges and \b Faces, which will be extruded, by one
96 <li><b>Select the whole mesh, sub-mesh or group</b> activating this
98 <li>Choose mesh elements with the mouse in the 3D Viewer. It is
99 possible to select a whole area with a mouse frame.</li>
100 <li>Input the element IDs directly in <b>Node IDs</b>, <b>Edge
101 IDs</b> and <b>Face IDs</b> fields. The selected elements will
102 be highlighted in the viewer, if the mesh is shown there.</li>
103 <li>Apply Filters. <b>Set filter</b> button allows to apply a
104 filter to the selection of elements. See more about filters in
105 the \ref filtering_elements "Selection filters" page.</li>
108 <li>Define the \b Path along which the elements will be extruded.<br>
109 Path definition consists of several elements:
111 <li><b>Mesh or sub-mesh</b> - 1D mesh or sub-mesh, along which
112 proceeds the extrusion.</li>
113 <li><b>Start node</b> - the start node of the Path. It is used
114 to define the direction of extrusion. </li>
117 <li>If you activate <b>Generate Groups</b> check-box, the <em>result elements</em>
118 created from <em>selected elements</em> contained in groups will be
119 included into new groups named by pattern "<old group
120 name>_extruded" and "<old group name>_top". For example if a
121 selected quadrangle is included in \a g_Faces group (see figures
122 below) then result hexahedra will be included in \a
123 g_Faces_extruded group and a quadrangle created at the "top" of
124 extruded mesh will be included in \a g_Faces_top group. <br>
125 \image html extrusion_groups.png
126 \image html extrusion_groups_res.png
127 <p> This check-box is active only if there are some groups in the mesh.
132 <li>There are two optional parameters, which can be very useful:
134 <li>If the path of extrusion is curvilinear, at each iteration the
135 extruded elements are rotated to keep its initial angularity to the
136 curve. By default, the <b>Base Point</b> around which the elements
137 are rotated is the mass center of the elements, however, you can
138 specify any point as the <b>Base Point</b> and the elements will be
139 rotated with respect to this point.<br>
140 Note that only the displacement of the <b>Base Point</b> exactly
141 equals to the path, and all other extruded elements simply keep
142 their position relatively to the <b>Base Point</b> at each
144 <li>The elements can also be rotated around the path to get the
145 resulting mesh in a helical fashion. You can set the values of
146 angles at the right, add them to the list of angles at the left by
147 pressing the <em>"Add"</em> button and remove them from the list by
148 pressing the <em>"Remove"</em> button.
150 <center><em>"Add" button</em></center>
151 \image html remove.png
152 <center><em>"Remove" button</em></center>
154 <b>Linear variation of the angles</b> option allows defining the angle
155 of gradual rotation for the whole path. At each step the elements will
156 be rotated by <code>angle / nb. of steps</code>.
162 <li>Click \b Apply or <b> Apply and Close</b> button to confirm the
163 operation. Mesh edges will be extruded into faces, faces into
164 volumes. The external surface of the resulting 3d mesh (if faces
165 have been extruded) is covered with faces, and corners with
166 edges. If the path is closed, the resulting mesh can contain
167 duplicated nodes and faces, because no sewing is done.
171 <br><b>See Also</b> a sample TUI Script of an
172 \ref tui_extrusion_along_path "Extrusion along a Path" operation.