3 \page extrusion_along_path_page Extrusion along a path
5 \n In principle, <b>Extrusion along a path</b> works in the same way
6 as \b Extrusion, the main difference is that we define not a vector,
7 but a path of extrusion which must be a 1D mesh or 1D sub-mesh.
8 To get an idea of how this algorithm works, examine several examples,
9 starting from the most simple case of extrusion along a straight edge.
10 In the examples the sample mesh will be extruded along different
11 paths and with different parameters.
12 This 2D mesh has two quadrangle faces and seven edges. Look
13 at the picture, where white digits are the node numbers and green
14 are the element numbers:
16 \image html mesh_for_extr_along_path.png
18 <br><center><h2>Extrusion along a straight edge</h2>(not using base point
21 \image html straight_before.png
22 <center>The image shows a 1D path mesh, built on a linear edge, and the initial 2D mesh.</center>
24 \image html straight_after.png
25 <center> The image shows the result of extrusion of two edges
26 (#1 and #2) of the initial mesh along the path. \n Node #1 of path mesh
27 has been selected as Start node.</center>
29 <br><center><h2>Extrusion along a curvilinear edge</h2>(with and
30 without angles)</center>
32 \image html curvi_simple_before.png
33 <center>The image shows a 1D path mesh, built on curvilinear edge, and
34 the initial 2D mesh.</center>
36 \image html curvi_simple_after.png
37 <center>The central image shows the result of extrusion of one edge
38 (#2) of the initial mesh along the path. \n Node #1 of path mesh has
39 been selected as <b>Start node</b>.</center>
41 \image html curvi_angles_after.png
42 <center>The same, but using angles {45, 45, 45, 0, -45, -45, -45}</center>
44 <br><center><h2>Extrusion of a 2D face along a mesh built on a wire</h2></center>
46 In this example the path mesh has been built on a wire containing 3
47 edges. Node 1 is a start node. Linear angle variation by 180 degrees
48 has also been applied.
50 \image html extr_along_wire_before.png
51 <center><em>Meshed wire</em></center>
53 \image html extr_along_wire_after.png
54 <center><em>The resulting extrusion</em></center>
56 <br><center><h2>Extrusion of 2d elements along a closed path</h2></center>
58 \image html circle_simple_before.png
59 <center>The image shows a path mesh built on a closed edge
62 \image html circle_simple_after.png
63 <center>The central image shows the result of extrusion of both faces
64 of the initial mesh. \n Note, that no sewing has been done, so, there are
65 six coincident nodes and two coincident faces in the resulting
68 \image html circle_angles_after.png
69 <center>The same, but using angles {45, -45, 45, -45, 45, -45, 45,
72 <br><em>To use Extrusion along a path:</em>
74 <li>From the \b Modification menu choose the <b>Extrusion along a
75 path</b> item or click <em>"Extrusion along a path"</em> button in the toolbar.
77 \image html image101.png
78 <center><em>"Extrusion along a path" button</em></center>
80 The following dialog common for line and planar elements will appear:
82 \image html extrusion1.png
87 <li>select the type of elements which will be extruded (1D or 2D),</li>
88 <li>specify the <b>IDs of the elements</b> which will be extruded
91 <li><b>Select the whole mesh, submesh or group</b> activating this
93 <li>choose mesh elements with the mouse in the 3D Viewer. It is
94 possible to select a whole area with a mouse frame; or</li>
95 <li>input the element IDs directly in <b>ID Elements</b> field. The selected elements will be highlighted in the
97 <li>apply Filters. <b>Set filter</b> button allows to apply a filter to the selection of elements. See more
98 about filters in the \ref selection_filter_library_page "Selection filter library" page.</li>
102 <li>define the Path along which the elements will be extruded,
103 \n Path definition consists of several elements:
105 <li><b>Mesh or submesh</b> - 1D mesh or sub-mesh, along which proceeds the extrusion</li>
106 <li><b>Start node</b> - the start node. It is used to define the direction of extrusion </li>
109 <li>activate <b>Generate Groups</b> checkbox if it is necessary to copy the groups of
110 elements of the source mesh to the newly created one. </li>
114 <li>There are two optional parameters, which can be very useful:
116 <li>If the path of extrusion is curvilinear, at each iteration the
117 extruded shape is rotated to keep its initial angularity to the
118 curve. By default, the <b>Base Point</b> around which the shape is rotated is
119 the mass center of the shape, however, you can specify any point as
120 the <b>Base Point</b> and the shape will be rotated with respect to this
123 <li>The shape can also be rotated around the path to get the resulting
124 mesh in a helical fashion. You can set the values of angles at the
125 right, add them to the list of angles at the left by pressing the <em>"Add"</em>
126 button and remove them from the list by pressing the <em>"Remove"</em> button.
129 <center><em>"Add" button</em></center>
131 \image html remove.png
132 <center><em>"Remove" button</em></center>
134 <b>Linear variation of the angles</b> option allows defining the angle of gradual rotation for the whole path.
135 At each step the shape will be rotated by angle/nb. of steps.
142 <li>Click \b Apply or <b> Apply and Close</b> button to confirm the operation.
143 Mesh edges will be extruded into
144 faces, faces into volumes. The external surface of the resulting 3d
145 mesh (if faces have been extruded) is covered with faces, and corners
146 with edges. If the path is closed, the resulting mesh can contain
147 duplicated nodes and faces, because no sewing is done.
151 <br><b>See Also</b> a sample TUI Script of an
152 \ref tui_extrusion_along_path "Extrusion along a Path" operation.