doc/salome/gui/SMESH/constructing_meshes.htm

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  94 <h1>Creating Meshes</h1>\r
  95 \r
  96 <p class="whs1">First of all see <a href="smesh_py_introduction.htm">Example \r
  97  of 3d mesh generation</a>, which is an example of good python script style \r
  98  for Mesh module. </p>\r
  99 \r
 100 <p class="whs1">Other examples of python \r
 101  scripts will be also updated soon to use smesh package instead of direct \r
 102  usage of idl interface. </p>\r
 103 \r
 104 <h3><a name=bookmark>Construction of a Mesh</a></h3>\r
 105 \r
 106 <p class="whs2"><span style="font-family: 'Lucida Console', monospace;">import \r
 107  geompy</span></p>\r
 108 \r
 109 <p class="whs2">import smesh</p>\r
 110 \r
 111 <p class="whs2">&nbsp;</p>\r
 112 \r
 113 <p class="whs3"># create a box</p>\r
 114 \r
 115 <p class="whs2">box = geompy.MakeBox(0., \r
 116  0., 0., 100., 200., 300.)</p>\r
 117 \r
 118 <p class="whs2">idbox = geompy.addToStudy(box, \r
 119  &quot;box&quot;)</p>\r
 120 \r
 121 <p class="whs2">&nbsp;</p>\r
 122 \r
 123 <p class="whs3"># create a mesh</p>\r
 124 \r
 125 <p class="whs2">tetra = smesh.Mesh(box, \r
 126  &quot;MeshBox&quot;)</p>\r
 127 \r
 128 <p class="whs2">&nbsp;</p>\r
 129 \r
 130 <p class="whs2">algo1D = tetra.Segment()</p>\r
 131 \r
 132 <p class="whs2">algo1D.NumberOfSegments(7)</p>\r
 133 \r
 134 <p class="whs2">&nbsp;</p>\r
 135 \r
 136 <p class="whs2">algo2D = tetra.Triangle()</p>\r
 137 \r
 138 <p class="whs2">algo2D.MaxElementArea(800.)</p>\r
 139 \r
 140 <p class="whs2">&nbsp;</p>\r
 141 \r
 142 <p class="whs2">algo3D = tetra.Tetrahedron(smesh.NETGEN)</p>\r
 143 \r
 144 <p class="whs2">algo3D.MaxElementVolume(900.)</p>\r
 145 \r
 146 <p class="whs2">&nbsp;</p>\r
 147 \r
 148 <p class="whs3"># compute the mesh</p>\r
 149 \r
 150 <p class="whs2">ret = tetra.Compute()</p>\r
 151 \r
 152 <p class="whs2">if ret == 0:</p>\r
 153 \r
 154 <p class="whs2">&nbsp;&nbsp;&nbsp;&nbsp;print \r
 155  &quot;problem when computing the mesh&quot;</p>\r
 156 \r
 157 <p class="whs2">else:</p>\r
 158 \r
 159 <p class="whs2">&nbsp;&nbsp;&nbsp;&nbsp;print \r
 160  &quot;mesh computed&quot;</p>\r
 161 \r
 162 <p class="whs2">&nbsp;&nbsp;&nbsp;&nbsp;pass \r
 163  </p>\r
 164 \r
 165 <p class="whs2">&nbsp;</p>\r
 166 \r
 167 <p class="whs2">&nbsp;</p>\r
 168 \r
 169 <h3><a name=bookmark1>Construction of a Submesh</a></h3>\r
 170 \r
 171 <p class="whs4"><span style="font-family: 'Lucida Console', monospace;">from \r
 172  geompy import *</span></p>\r
 173 \r
 174 <p class="whs4">import smesh</p>\r
 175 \r
 176 <p class="whs4">&nbsp;</p>\r
 177 \r
 178 <p class="whs5"># create a box</p>\r
 179 \r
 180 <p class="whs4">box = MakeBoxDXDYDZ(10., 10., 10.)</p>\r
 181 \r
 182 <p class="whs4">addToStudy(box, &quot;Box&quot;)</p>\r
 183 \r
 184 <p class="whs4">&nbsp;</p>\r
 185 \r
 186 <p class="whs5"># select one edge of \r
 187  the box for definition of a local hypothesis</p>\r
 188 \r
 189 <p class="whs4">p5 = MakeVertex(5., 0., 0.)</p>\r
 190 \r
 191 <p class="whs4">EdgeX = GetEdgeNearPoint(box, p5)</p>\r
 192 \r
 193 <p class="whs4">addToStudyInFather(box, EdgeX, &quot;Edge \r
 194  [0,0,0 - 10,0,0]&quot;)</p>\r
 195 \r
 196 <p class="whs4">&nbsp;</p>\r
 197 \r
 198 <p class="whs5"># create a hexahedral \r
 199  mesh on the box</p>\r
 200 \r
 201 <p class="whs4">quadra = smesh.Mesh(box, &quot;Box : quadrangle \r
 202  2D mesh&quot;)</p>\r
 203 \r
 204 <p class="whs4">&nbsp;</p>\r
 205 \r
 206 <p class="whs5"># create a regular \r
 207  1D algorithm for the faces</p>\r
 208 \r
 209 <p class="whs4">algo1D = quadra.Segment()</p>\r
 210 \r
 211 <p class="whs4">&nbsp;</p>\r
 212 \r
 213 <p class="whs5"># define &quot;NumberOfSegments&quot; \r
 214  hypothesis to cut</p>\r
 215 \r
 216 <p class="whs5"># all the edges in \r
 217  a fixed number of segments</p>\r
 218 \r
 219 <p class="whs4">algo1D.NumberOfSegments(4)</p>\r
 220 \r
 221 <p class="whs4">&nbsp;</p>\r
 222 \r
 223 <p class="whs5"># create a quadrangle \r
 224  2D algorithm for the faces</p>\r
 225 \r
 226 <p class="whs4">quadra.Quadrangle()</p>\r
 227 \r
 228 <p class="whs4">&nbsp;</p>\r
 229 \r
 230 <p class="whs5"># construct a submesh \r
 231  on the edge with a local hypothesis</p>\r
 232 \r
 233 <p class="whs4">algo_local = quadra.Segment(EdgeX)</p>\r
 234 \r
 235 <p class="whs4">&nbsp;</p>\r
 236 \r
 237 <p class="whs5"># define &quot;Arithmetic1D&quot; \r
 238  hypothesis to cut the edge<span style="margin-top: 0px;\r
 239                                                                                 margin-bottom: 0px;\r
 240                                                                                 font-family: 'Times New Roman', serif;"> \r
 241  in several segments with increasing arithmetic length</span></p>\r
 242 \r
 243 <p class="whs4">algo_local.Arithmetic1D(1, 4)</p>\r
 244 \r
 245 <p class="whs4">&nbsp;</p>\r
 246 \r
 247 <p class="whs5"># define &quot;Propagation&quot; \r
 248  hypothesis that propagates all other hypotheses</p>\r
 249 \r
 250 <p class="whs5"># on all edges of the \r
 251  opposite side in case of quadrangular faces</p>\r
 252 \r
 253 <p class="whs4">algo_local.Propagation()</p>\r
 254 \r
 255 <p class="whs4">&nbsp;</p>\r
 256 \r
 257 <p class="whs5"># compute the mesh</p>\r
 258 \r
 259 <p class="whs4">quadra.Compute() </p>\r
 260 \r
 261 <p class="whs4">&nbsp;</p>\r
 262 \r
 263 <h3><a name=bookmark2>Editing of a mesh</a></h3>\r
 264 \r
 265 <p class="whs4"><span style="font-family: 'Lucida Console', monospace;">import \r
 266  geompy</span></p>\r
 267 \r
 268 <p class="whs4">import smesh</p>\r
 269 \r
 270 <p class="whs4">&nbsp;</p>\r
 271 \r
 272 <p class="whs4">def PrintMeshInfo(theMesh):</p>\r
 273 \r
 274 <p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;aMesh \r
 275  = theMesh.GetMesh()</p>\r
 276 \r
 277 <p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print \r
 278  &quot;Information about mesh:&quot;</p>\r
 279 \r
 280 <p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print \r
 281  &quot;Number of nodes &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: \r
 282  &quot;, aMesh.NbNodes()</p>\r
 283 \r
 284 <p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print \r
 285  &quot;Number of edges &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: \r
 286  &quot;, aMesh.NbEdges()</p>\r
 287 \r
 288 <p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print \r
 289  &quot;Number of faces &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: \r
 290  &quot;, aMesh.NbFaces()</p>\r
 291 \r
 292 <p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print \r
 293  &quot;Number of volumes &nbsp;&nbsp;&nbsp;&nbsp;: \r
 294  &quot;, aMesh.NbVolumes()</p>\r
 295 \r
 296 <p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;pass</p>\r
 297 \r
 298 <p class="whs4">&nbsp;</p>\r
 299 \r
 300 <p class="whs5"># create a box</p>\r
 301 \r
 302 <p class="whs4">box = geompy.MakeBox(0., 0., 0., 20., \r
 303  20., 20.)</p>\r
 304 \r
 305 <p class="whs4">geompy.addToStudy(box, &quot;box&quot;)</p>\r
 306 \r
 307 <p class="whs4">&nbsp;</p>\r
 308 \r
 309 <p class="whs5"># select one edge of \r
 310  the box for definition of a local hypothesis</p>\r
 311 \r
 312 <p class="whs4">subShapeList = geompy.SubShapeAll(box, \r
 313  geompy.ShapeType[&quot;EDGE&quot;])</p>\r
 314 \r
 315 <p class="whs4">edge = subShapeList[0]</p>\r
 316 \r
 317 <p class="whs4">name = geompy.SubShapeName(edge, box)</p>\r
 318 \r
 319 <p class="whs4">geompy.addToStudyInFather(box, edge, name)</p>\r
 320 \r
 321 <p class="whs4">&nbsp;</p>\r
 322 \r
 323 <p class="whs5"># create a mesh</p>\r
 324 \r
 325 <p class="whs4">tria = smesh.Mesh(box, &quot;Mesh 2D&quot;)</p>\r
 326 \r
 327 <p class="whs4">algo1D = tria.Segment()</p>\r
 328 \r
 329 <p class="whs4">hyp1 = algo1D.NumberOfSegments(3)</p>\r
 330 \r
 331 <p class="whs4">algo2D = tria.Triangle()</p>\r
 332 \r
 333 <p class="whs4">hyp2 = algo2D.MaxElementArea(10.)</p>\r
 334 \r
 335 <p class="whs4">&nbsp;</p>\r
 336 \r
 337 <p class="whs5"># create a sub-mesh</p>\r
 338 \r
 339 <p class="whs4">algo_local = tria.Segment(edge)</p>\r
 340 \r
 341 <p class="whs4">hyp3 = algo_local.Arithmetic1D(1, 6)</p>\r
 342 \r
 343 <p class="whs4">hyp4 = algo_local.Propagation()</p>\r
 344 \r
 345 <p class="whs4">&nbsp;</p>\r
 346 \r
 347 <p class="whs5"># compute the mesh</p>\r
 348 \r
 349 <p class="whs4">tria.Compute()</p>\r
 350 \r
 351 <p class="whs4">PrintMeshInfo(tria)</p>\r
 352 \r
 353 <p class="whs4">&nbsp;</p>\r
 354 \r
 355 <p class="whs5"># remove a local hypothesis</p>\r
 356 \r
 357 <p class="whs4">mesh = tria.GetMesh()</p>\r
 358 \r
 359 <p class="whs4">mesh.RemoveHypothesis(edge, hyp4)</p>\r
 360 \r
 361 <p class="whs4">&nbsp;</p>\r
 362 \r
 363 <p class="whs5"># compute the mesh</p>\r
 364 \r
 365 <p class="whs4">tria.Compute()</p>\r
 366 \r
 367 <p class="whs4">PrintMeshInfo(tria)</p>\r
 368 \r
 369 <p class="whs4">&nbsp;</p>\r
 370 \r
 371 <p class="whs5"># change the value \r
 372  of the 2D hypothesis</p>\r
 373 \r
 374 <p class="whs4">hyp2.SetMaxElementArea(2.)</p>\r
 375 \r
 376 <p class="whs4">&nbsp;</p>\r
 377 \r
 378 <p class="whs5"># compute the mesh</p>\r
 379 \r
 380 <p class="whs4">tria.Compute()</p>\r
 381 \r
 382 <p class="whs4">PrintMeshInfo(tria) </p>\r
 383 \r
 384 <p class="whs6">&nbsp;</p>\r
 385 \r
 386 <h3><a name=bookmark3>Export of a Mesh</a></h3>\r
 387 \r
 388 <p class="whs7">import geompy</p>\r
 389 \r
 390 <p class="whs7">import smesh</p>\r
 391 \r
 392 <p class="whs6">&nbsp;</p>\r
 393 \r
 394 <p class="whs6"># create a box</p>\r
 395 \r
 396 <p class="whs7">box = geompy.MakeBox(0., \r
 397  0., 0., 100., 200., 300.)</p>\r
 398 \r
 399 <p class="whs7">idbox = geompy.addToStudy(box, \r
 400  &quot;box&quot;)</p>\r
 401 \r
 402 <p class="whs6">&nbsp;</p>\r
 403 \r
 404 <p class="whs6"># create a mesh</p>\r
 405 \r
 406 <p class="whs7">tetra = smesh.Mesh(box, \r
 407  &quot;MeshBox&quot;)</p>\r
 408 \r
 409 <p class="whs6">&nbsp;</p>\r
 410 \r
 411 <p class="whs7">algo1D = tetra.Segment()</p>\r
 412 \r
 413 <p class="whs7">algo1D.NumberOfSegments(7)</p>\r
 414 \r
 415 <p class="whs7">&nbsp;</p>\r
 416 \r
 417 <p class="whs7">algo2D = tetra.Triangle()</p>\r
 418 \r
 419 <p class="whs7">algo2D.MaxElementArea(800.)</p>\r
 420 \r
 421 <p class="whs7">&nbsp;</p>\r
 422 \r
 423 <p class="whs7">algo3D = tetra.Tetrahedron(smesh.NETGEN)</p>\r
 424 \r
 425 <p class="whs7">algo3D.MaxElementVolume(900.)</p>\r
 426 \r
 427 <p class="whs6">&nbsp;</p>\r
 428 \r
 429 <p class="whs6"># compute the mesh</p>\r
 430 \r
 431 <p class="whs7">tetra.Compute()</p>\r
 432 \r
 433 <p class="whs6">&nbsp;</p>\r
 434 \r
 435 <p class="whs6"># export the mesh in a \r
 436  MED file</p>\r
 437 \r
 438 <p class="whs7">tetra.ExportMED(&quot;/tmp/meshMED.med&quot;, \r
 439  0) </p>\r
 440 \r
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