smesh/doc/salome/gui/SMESH/constructing_meshes.htm

<!doctype HTML public "-//W3C//DTD HTML 4.0 Frameset//EN">

<html>

<head>
<title>Constructing Meshes</title>
<meta http-equiv="content-type" content="text/html; charset=windows-1252">
<meta name="generator" content="RoboHelp by eHelp Corporation www.ehelp.com"><style type="text/css">
<!--
p.whs1 { margin-top:0pt; margin-bottom:0pt; }
p.whs2 { margin-top:0pt; margin-bottom:0pt; font-family:'Lucida Console' , monospace; }
p.whs3 { margin-top:0pt; margin-bottom:0pt; font-family:'Times New Roman' , serif; }
p.whs4 { font-family:'Lucida Console' , monospace; margin-top:0px; margin-bottom:0px; }
p.whs5 { margin-top:0px; margin-bottom:0px; font-family:'Times New Roman' , serif; }
p.whs6 { margin-top:0px; margin-bottom:0px; }
p.whs7 { margin-top:0px; margin-bottom:0px; font-family:'Lucida Console' , monospace; }
-->
</style><script type="text/javascript" language="JavaScript">
<!--
if ((navigator.appName == "Netscape") && (parseInt(navigator.appVersion) == 4))
{
  var strNSS = "<style type='text/css'>";
  strNSS += "p.whs1 {margin-top:1pt;margin-bottom:1pt; }";
  strNSS += "p.whs2 {margin-top:1pt;margin-bottom:1pt; }";
  strNSS += "p.whs3 {margin-top:1pt;margin-bottom:1pt; }";
  strNSS += "p.whs4 {margin-top:1pt;margin-bottom:1pt; }";
  strNSS += "p.whs5 {margin-top:1pt;margin-bottom:1pt; }";
  strNSS += "p.whs6 {margin-top:1pt;margin-bottom:1pt; }";
  strNSS += "p.whs7 {margin-top:1pt;margin-bottom:1pt; }";
  strNSS +="</style>";
  document.write(strNSS);
}
//-->
</script>
<script type="text/javascript" language="JavaScript" title="WebHelpInlineScript">
<!--
function reDo() {
  if (innerWidth != origWidth || innerHeight != origHeight)
     location.reload();
}
if ((parseInt(navigator.appVersion) == 4) && (navigator.appName == "Netscape")) {
	origWidth = innerWidth;
	origHeight = innerHeight;
	onresize = reDo;
}
onerror = null; 
//-->
</script>
<style type="text/css">
<!--
div.WebHelpPopupMenu { position:absolute; left:0px; top:0px; z-index:4; visibility:hidden; }
p.WebHelpNavBar { text-align:right; }
-->
</style><script type="text/javascript" language="javascript1.2" src="whmsg.js"></script>
<script type="text/javascript" language="javascript" src="whver.js"></script>
<script type="text/javascript" language="javascript1.2" src="whproxy.js"></script>
<script type="text/javascript" language="javascript1.2" src="whutils.js"></script>
<script type="text/javascript" language="javascript1.2" src="whtopic.js"></script>
<script type="text/javascript" language="javascript1.2">
<!--
if (window.gbWhTopic)
{
	if (window.setRelStartPage)
	{
	addTocInfo("MESH module\nTUI Scripts\nCreating Meshes");
addButton("show",BTN_IMG,"Show","","","","",0,0,"whd_show0.gif","whd_show2.gif","whd_show1.gif");
addButton("hide",BTN_IMG,"Hide","","","","",0,0,"whd_hide0.gif","whd_hide2.gif","whd_hide1.gif");

	}


	if (window.setRelStartPage)
	{
	setRelStartPage("index.htm");

		autoSync(1);
		sendSyncInfo();
		sendAveInfoOut();
	}

}
else
	if (window.gbIE4)
		document.location.reload();
//-->
</script>
</head>
<body><script type="text/javascript" language="javascript1.2">
<!--
if (window.writeIntopicBar)
	writeIntopicBar(4);
//-->
</script>
<h1>Creating Meshes</h1>

<p class="whs1">First of all see <a href="smesh_py_introduction.htm">Example 
 of 3d mesh generation</a>, which is an example of good python script style 
 for Mesh module. </p>

<p class="whs1">Other examples of python 
 scripts will be also updated soon to use smesh package instead of direct 
 usage of idl interface. </p>

<h3><a name=bookmark>Construction of a Mesh</a></h3>

<p class="whs2"><span style="font-family: 'Lucida Console', monospace;">import 
 geompy</span></p>

<p class="whs2">import smesh</p>

<p class="whs2">&nbsp;</p>

<p class="whs3"># create a box</p>

<p class="whs2">box = geompy.MakeBox(0., 
 0., 0., 100., 200., 300.)</p>

<p class="whs2">idbox = geompy.addToStudy(box, 
 &quot;box&quot;)</p>

<p class="whs2">&nbsp;</p>

<p class="whs3"># create a mesh</p>

<p class="whs2">tetra = smesh.Mesh(box, 
 &quot;MeshBox&quot;)</p>

<p class="whs2">&nbsp;</p>

<p class="whs2">algo1D = tetra.Segment()</p>

<p class="whs2">algo1D.NumberOfSegments(7)</p>

<p class="whs2">&nbsp;</p>

<p class="whs2">algo2D = tetra.Triangle()</p>

<p class="whs2">algo2D.MaxElementArea(800.)</p>

<p class="whs2">&nbsp;</p>

<p class="whs2">algo3D = tetra.Tetrahedron(smesh.NETGEN)</p>

<p class="whs2">algo3D.MaxElementVolume(900.)</p>

<p class="whs2">&nbsp;</p>

<p class="whs3"># compute the mesh</p>

<p class="whs2">ret = tetra.Compute()</p>

<p class="whs2">if ret == 0:</p>

<p class="whs2">&nbsp;&nbsp;&nbsp;&nbsp;print 
 &quot;problem when computing the mesh&quot;</p>

<p class="whs2">else:</p>

<p class="whs2">&nbsp;&nbsp;&nbsp;&nbsp;print 
 &quot;mesh computed&quot;</p>

<p class="whs2">&nbsp;&nbsp;&nbsp;&nbsp;pass 
 </p>

<p class="whs2">&nbsp;</p>

<p class="whs2">&nbsp;</p>

<h3><a name=bookmark1>Construction of a Submesh</a></h3>

<p class="whs4"><span style="font-family: 'Lucida Console', monospace;">from 
 geompy import *</span></p>

<p class="whs4">import smesh</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># create a box</p>

<p class="whs4">box = MakeBoxDXDYDZ(10., 10., 10.)</p>

<p class="whs4">addToStudy(box, &quot;Box&quot;)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># select one edge of 
 the box for definition of a local hypothesis</p>

<p class="whs4">p5 = MakeVertex(5., 0., 0.)</p>

<p class="whs4">EdgeX = GetEdgeNearPoint(box, p5)</p>

<p class="whs4">addToStudyInFather(box, EdgeX, &quot;Edge 
 [0,0,0 - 10,0,0]&quot;)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># create a hexahedral 
 mesh on the box</p>

<p class="whs4">quadra = smesh.Mesh(box, &quot;Box : quadrangle 
 2D mesh&quot;)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># create a regular 
 1D algorithm for the faces</p>

<p class="whs4">algo1D = quadra.Segment()</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># define &quot;NumberOfSegments&quot; 
 hypothesis to cut</p>

<p class="whs5"># all the edges in 
 a fixed number of segments</p>

<p class="whs4">algo1D.NumberOfSegments(4)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># create a quadrangle 
 2D algorithm for the faces</p>

<p class="whs4">quadra.Quadrangle()</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># construct a submesh 
 on the edge with a local hypothesis</p>

<p class="whs4">algo_local = quadra.Segment(EdgeX)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># define &quot;Arithmetic1D&quot; 
 hypothesis to cut the edge<span style="margin-top: 0px;
										margin-bottom: 0px;
										font-family: 'Times New Roman', serif;"> 
 in several segments with increasing arithmetic length</span></p>

<p class="whs4">algo_local.Arithmetic1D(1, 4)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># define &quot;Propagation&quot; 
 hypothesis that propagates all other hypotheses</p>

<p class="whs5"># on all edges of the 
 opposite side in case of quadrangular faces</p>

<p class="whs4">algo_local.Propagation()</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># compute the mesh</p>

<p class="whs4">quadra.Compute() </p>

<p class="whs4">&nbsp;</p>

<h3><a name=bookmark2>Editing of a mesh</a></h3>

<p class="whs4"><span style="font-family: 'Lucida Console', monospace;">import 
 geompy</span></p>

<p class="whs4">import smesh</p>

<p class="whs4">&nbsp;</p>

<p class="whs4">def PrintMeshInfo(theMesh):</p>

<p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;aMesh 
 = theMesh.GetMesh()</p>

<p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print 
 &quot;Information about mesh:&quot;</p>

<p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print 
 &quot;Number of nodes &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: 
 &quot;, aMesh.NbNodes()</p>

<p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print 
 &quot;Number of edges &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: 
 &quot;, aMesh.NbEdges()</p>

<p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print 
 &quot;Number of faces &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: 
 &quot;, aMesh.NbFaces()</p>

<p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;print 
 &quot;Number of volumes &nbsp;&nbsp;&nbsp;&nbsp;: 
 &quot;, aMesh.NbVolumes()</p>

<p class="whs4">&nbsp;&nbsp;&nbsp;&nbsp;pass</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># create a box</p>

<p class="whs4">box = geompy.MakeBox(0., 0., 0., 20., 
 20., 20.)</p>

<p class="whs4">geompy.addToStudy(box, &quot;box&quot;)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># select one edge of 
 the box for definition of a local hypothesis</p>

<p class="whs4">subShapeList = geompy.SubShapeAll(box, 
 geompy.ShapeType[&quot;EDGE&quot;])</p>

<p class="whs4">edge = subShapeList[0]</p>

<p class="whs4">name = geompy.SubShapeName(edge, box)</p>

<p class="whs4">geompy.addToStudyInFather(box, edge, name)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># create a mesh</p>

<p class="whs4">tria = smesh.Mesh(box, &quot;Mesh 2D&quot;)</p>

<p class="whs4">algo1D = tria.Segment()</p>

<p class="whs4">hyp1 = algo1D.NumberOfSegments(3)</p>

<p class="whs4">algo2D = tria.Triangle()</p>

<p class="whs4">hyp2 = algo2D.MaxElementArea(10.)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># create a sub-mesh</p>

<p class="whs4">algo_local = tria.Segment(edge)</p>

<p class="whs4">hyp3 = algo_local.Arithmetic1D(1, 6)</p>

<p class="whs4">hyp4 = algo_local.Propagation()</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># compute the mesh</p>

<p class="whs4">tria.Compute()</p>

<p class="whs4">PrintMeshInfo(tria)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># remove a local hypothesis</p>

<p class="whs4">mesh = tria.GetMesh()</p>

<p class="whs4">mesh.RemoveHypothesis(edge, hyp4)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># compute the mesh</p>

<p class="whs4">tria.Compute()</p>

<p class="whs4">PrintMeshInfo(tria)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># change the value 
 of the 2D hypothesis</p>

<p class="whs4">hyp2.SetMaxElementArea(2.)</p>

<p class="whs4">&nbsp;</p>

<p class="whs5"># compute the mesh</p>

<p class="whs4">tria.Compute()</p>

<p class="whs4">PrintMeshInfo(tria) </p>

<p class="whs6">&nbsp;</p>

<h3><a name=bookmark3>Export of a Mesh</a></h3>

<p class="whs7">import geompy</p>

<p class="whs7">import smesh</p>

<p class="whs6">&nbsp;</p>

<p class="whs6"># create a box</p>

<p class="whs7">box = geompy.MakeBox(0., 
 0., 0., 100., 200., 300.)</p>

<p class="whs7">idbox = geompy.addToStudy(box, 
 &quot;box&quot;)</p>

<p class="whs6">&nbsp;</p>

<p class="whs6"># create a mesh</p>

<p class="whs7">tetra = smesh.Mesh(box, 
 &quot;MeshBox&quot;)</p>

<p class="whs6">&nbsp;</p>

<p class="whs7">algo1D = tetra.Segment()</p>

<p class="whs7">algo1D.NumberOfSegments(7)</p>

<p class="whs7">&nbsp;</p>

<p class="whs7">algo2D = tetra.Triangle()</p>

<p class="whs7">algo2D.MaxElementArea(800.)</p>

<p class="whs7">&nbsp;</p>

<p class="whs7">algo3D = tetra.Tetrahedron(smesh.NETGEN)</p>

<p class="whs7">algo3D.MaxElementVolume(900.)</p>

<p class="whs6">&nbsp;</p>

<p class="whs6"># compute the mesh</p>

<p class="whs7">tetra.Compute()</p>

<p class="whs6">&nbsp;</p>

<p class="whs6"># export the mesh in a 
 MED file</p>

<p class="whs7">tetra.ExportMED(&quot;/tmp/meshMED.med&quot;, 
 0) </p>

<script type="text/javascript" language="javascript1.2">
<!--
if (window.writeIntopicBar)
	writeIntopicBar(0);
//-->
</script>
</body>
</html>