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83 <h1>Sewing meshes</h1>
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85 <p><img src="../i_blue.jpg" x-maintain-ratio="TRUE" width="30px" height="30px" border="0" class="img_whs1"> In SMESH you can sew elements of different
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86 meshes. The current functionality allows you to sew:</p>
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90 <ul type="disc" class="whs2">
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92 <li class=kadov-p><p class="whs3"><a href="#free bord">Free
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93 borders </a></p></li>
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95 <li class=kadov-p><p class="whs3"><a href="#conform">Conform
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96 free borders</a></p></li>
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98 <li class=kadov-p><p class="whs3"><a href="#border to side">Border
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99 to side</a></p></li>
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101 <li class=kadov-p><p class="whs3"><a href="#side elements">Side
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102 elements</a></p></li>
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105 <p class="whs3"> </p>
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107 <p class=TODO>To sew elements of different meshes:</p>
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109 <p class=TODO> </p>
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111 <p class="whs4">1. From the <span style="font-weight: bold;"><B>Modification
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112 </B></span>menu choose the <span style="font-weight: bold;"><B>Transformation
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113 </B></span>item and from
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114 its sub-menu select the <span style="font-weight: bold;"><B>Sewing </B></span>item.
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115 The following dialog box shall appear:</p>
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117 <p class="whs4"> </p>
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119 <p class="whs4"><img src="../image57.gif" width="311px" height="456px" border="0" class="img_whs5"></p>
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121 <p class="whs4"> </p>
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123 <p class="whs4">2. In the upper part of this dialog box check
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124 one of the radio buttons corresponding to the type of sewing operation
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125 you would like to perform: </p>
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127 <p class="whs4"> </p>
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129 <p class="whs4"><img src="../image61.gif" width="297px" height="62px" border="0" class="img_whs6"> </p>
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131 <p class="whs4"> </p>
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133 <p class="whs4">3. Fill the other fields available in the
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136 <p class="whs4">4. Click the <span style="font-weight: bold;"><B>OK
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137 </B></span><span>or </span><span style="font-weight: bold;"><B>Apply </B></span>button
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138 to perform the operation of sewing. </p>
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140 <p class="whs3"> </p>
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142 <h3><a name="free bord"></a>Sew free borders</h3>
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144 <p>This functionality allows you to unite two free borders of a 2D mesh.</p>
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148 <p>For sewing free borders you should define three points on each border:
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149 first, second and the last node: </p>
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153 <ul type="disc" class="whs2">
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155 <li class=kadov-p><p> the
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156 first node specifies beginning of the border ;</p></li>
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158 <li class=kadov-p><p> the
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159 second node specifies the part of the border which should be considered
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160 (as far as the free border usually forms a closed contour);</p></li>
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162 <li class=kadov-p><p> the
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163 last node specifies the end of the border.</p></li>
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168 <p>You can select these nodes in the 3D viewer or define by its id.</p>
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172 <p>The first and the second nodes should belong to the same link of a face.
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173 The second and the last nodes of a border can be the same. The first and
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174 the last nodes of two borders can be the same. The corresponding end nodes
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175 of two borders will be merged. Intermediate nodes of two borders will
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176 be either merged or inserted into faces of the opposite border.</p>
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180 <p>The sewing algorithm is as follows:</p>
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184 <p class="whs4">1. The parameter (U) of each node within
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185 a border is computed. So that the first node has U=0.0, the last node
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186 has U=1.0, for the rest nodes 0.0 < U < 1.0;</p>
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188 <p class="whs4">2. Compare node parameters of the two borders.
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189 If two nodes of the opposite borders have close parameters, they are merged,
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190 i.e. a node of the first border is replaced in all elements by a node
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191 of the second border. If a node has no node with a close parameter in
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192 the opposite border, it is inserted into an edge of element of the opposite
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193 border, an element is split. Two nodes are considered close enough to
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194 merge, if difference of their parameters is less than one fifth of minimum
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195 length of adjacent face edges on the borders.</p>
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199 <p class="whs4"><img src="../image22.jpg" width="612px" height="225px" border="0" class="img_whs7"></p>
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201 <p class="whs4"> </p>
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203 <h3><a name=conform></a>Sew conform free borders</h3>
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205 <p>This functionality can be used to unite two free borders of a 2D mesh.</p>
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209 <p>The borders of meshes for sewing are defined as for "Sew free borders"
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210 except that the second free border is not limited and can be defined by
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211 the first and the second nodes only. The first nodes of two borders can
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216 <p class="whs4"><img src="../image23.jpg" width="612px" height="230px" border="0" class="img_whs8"></p>
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218 <p>The algorithm is following: counting nodes starting at the first ones,
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219 the n-th node of the first border is merged with the n-th node of the
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220 other border, until the end of either of borders. Nodes of the first border
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221 are replaced in all elements with corresponding nodes of the second border.</p>
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223 <p>For sewing conform free borders you should define three points on the
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224 first border and two points on the second one. User can select these nodes
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225 in 3D viewer or define node by its id.</p>
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227 <p class="whs3"> </p>
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229 <p class="whs3"> </p>
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231 <h3><a name="border to side"></a>Sew border to side</h3>
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233 <p>"Sew border to side" is intended to sew a free border to a
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236 <p>The free border is defined as for "Sewing of free borders".
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237 The place where to sew the border is defined by two nodes, between which
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238 the border faces are placed, so that the first border node is merged with
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239 the first node on the side and the last node of the border is merged with
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240 the second specified node on the side.</p>
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244 <p class="whs4"><img src="../image30.jpg" width="600px" height="227px" border="0" class="img_whs9"></p>
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246 <p>The algorithm is following.</p>
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248 <p>1. Find a sequence of linked nodes on the side such that the found links
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249 to be most co-directed with the links of the free border.</p>
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251 <p>2. Sew two sequences of nodes using algorithm of "Sewing of free
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254 <p>For sewing border to side you should define three points on the border
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255 and two points on the side. User can select these nodes in 3D viewer or
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256 define node by its id.</p>
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260 <h3><a name="side elements"></a>Sew side elements</h3>
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262 <p class="whs4"> </p>
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266 <p class="whs4"><img src="../image31.jpg" width="620px" height="228px" border="0" class="img_whs10"></p>
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268 <p>This operation is intended to unite two mesh surfaces.</p>
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270 <p>Surfaces may be defined by either 2d or 3d elements. The number of given
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271 elements of the sides must be the same. The sets of given elements must
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272 be topologically equal, i.e. each node of one element set must have a
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273 corresponding node in the other element set and corresponding nodes must
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274 be equally linked. If there are 3d elements in a set, only their free
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275 faces must obey to that rule.</p>
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277 <p>Two corresponding nodes on each side must be specified. They must belong
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278 to one element and must be located on an element set boundary.</p>
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280 <p>Sewing algorithm finds and merges the corresponding nodes starting from
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281 the specified ones.</p>
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285 <p class="whs4"><img src="../image32.jpg" width="304px" height="222px" border="0" class="img_whs11"></p>
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287 <p>For sewing side elements you should define elements for sewing and two
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288 nodes for merging on the each side. User can select these elements and
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289 nodes in 3D viewer or define them by its id.</p>
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