smesh/doc/salome/gui/SMESH/input/tui_creating_meshes.doc

/*!

\page tui_creating_meshes_page Creating Meshes

\n First of all see \ref introduction_to_mesh_python_page "Example of 3d mesh generation",
 which is an example of good python script style for Mesh module.

<br>
<h2>Construction of a Mesh</h2>

\code
import geompy
import smesh

# create a box
box = geompy.MakeBox(0., 0., 0., 100., 200., 300.)
idbox = geompy.addToStudy(box, "box")

# create a mesh
tetra = smesh.Mesh(box, "MeshBox")

algo1D = tetra.Segment()
algo1D.NumberOfSegments(7)

algo2D = tetra.Triangle()
algo2D.MaxElementArea(800.)

algo3D = tetra.Tetrahedron(smesh.NETGEN)
algo3D.MaxElementVolume(900.)

# compute the mesh
ret = tetra.Compute()
if ret == 0:
    print "problem when computing the mesh"
else:
    print "mesh computed"
    pass
\endcode

<br>
\anchor tui_construction_submesh
<h2>Construction of a Submesh</h2>

\code
from geompy import *
import smesh

# create a box
box = MakeBoxDXDYDZ(10., 10., 10.)
addToStudy(box, "Box")

# select one edge of the box for definition of a local hypothesis
p5 = MakeVertex(5., 0., 0.)
EdgeX = GetEdgeNearPoint(box, p5)
addToStudyInFather(box, EdgeX, "Edge [0,0,0 - 10,0,0]")

# create a hexahedral mesh on the box
quadra = smesh.Mesh(box, "Box : quadrangle 2D mesh")

# create a regular 1D algorithm for the faces
algo1D = quadra.Segment()

# define "NumberOfSegments" hypothesis to cut
# all the edges in a fixed number of segments
algo1D.NumberOfSegments(4)

# create a quadrangle 2D algorithm for the faces
quadra.Quadrangle()

# construct a submesh on the edge with a local hypothesis
algo_local = quadra.Segment(EdgeX)

# define "Arithmetic1D" hypothesis to cut the edge in several segments with increasing arithmetic length
algo_local.Arithmetic1D(1, 4)

# define "Propagation" hypothesis that propagates all other hypotheses
# on all edges of the opposite side in case of quadrangular faces
algo_local.Propagation()

# compute the mesh
quadra.Compute()

\endcode

<br>
\anchor tui_editing_mesh
<h2>Editing of a mesh</h2>

\code
import geompy
import smesh

def PrintMeshInfo(theMesh):
    aMesh = theMesh.GetMesh()
    print "Information about mesh:"
    print "Number of nodes       : ", aMesh.NbNodes()
    print "Number of edges       : ", aMesh.NbEdges()
    print "Number of faces       : ", aMesh.NbFaces()
    print "Number of volumes     : ", aMesh.NbVolumes()
    pass

# create a box
box = geompy.MakeBox(0., 0., 0., 20., 20., 20.)
geompy.addToStudy(box, "box")

# select one edge of the box for definition of a local hypothesis
subShapeList = geompy.SubShapeAll(box, geompy.ShapeType["EDGE"])
edge = subShapeList[0]
name = geompy.SubShapeName(edge, box)
geompy.addToStudyInFather(box, edge, name)

# create a mesh
tria = smesh.Mesh(box, "Mesh 2D")
algo1D = tria.Segment()
hyp1 = algo1D.NumberOfSegments(3)
algo2D = tria.Triangle()
hyp2 = algo2D.MaxElementArea(10.)

# create a sub-mesh
algo_local = tria.Segment(edge)
hyp3 = algo_local.Arithmetic1D(1, 6)
hyp4 = algo_local.Propagation()

# compute the mesh
tria.Compute()
PrintMeshInfo(tria)

# remove a local hypothesis
mesh = tria.GetMesh()
mesh.RemoveHypothesis(edge, hyp4)

# compute the mesh
tria.Compute()
PrintMeshInfo(tria)

# change the value of the 2D hypothesis
hyp2.SetMaxElementArea(2.)

# compute the mesh
tria.Compute()
PrintMeshInfo(tria)
\endcode

<br>
\anchor tui_export_mesh
<h2>Export of a Mesh</h2>

\code
import geompy
import smesh

# create a box
box = geompy.MakeBox(0., 0., 0., 100., 200., 300.)
idbox = geompy.addToStudy(box, "box")

# create a mesh
tetra = smesh.Mesh(box, "MeshBox")

algo1D = tetra.Segment()
algo1D.NumberOfSegments(7)

algo2D = tetra.Triangle()
algo2D.MaxElementArea(800.)

algo3D = tetra.Tetrahedron(smesh.NETGEN)
algo3D.MaxElementVolume(900.)

# compute the mesh
tetra.Compute()

# export the mesh in a MED file
tetra.ExportMED("/tmp/meshMED.med", 0)
\endcode

<br>
<h2>How to mesh a cylinder with hexahedrons?</h2>
Here you can see an example of python script, creating a hexahedral
mesh on a cylinder. And a picture below the source code of the script,
demonstrating the resulting mesh.
\include ex24_cylinder.py

\image html mesh_cylinder_hexa.png

*/