EDF Exercise 11

Work with scripts only

This sample is known to work on the latest SALOME release.
The compatibility with previous versions of SALOME is not guaranteed, though the sample can work on old versions also.

Objective

The objective of this exercise is to learn working with Python scripts in SALOME. The scripts allow to parameterize studies and to limit the disk space for the storage.

The attached sample Python SALOME script can be the base for all your future studies. To practice in the usage of the scripts, it is suggested to construct a parameterized cube in 3 different ways and to learn some elementary geometric Python functions. Then we are going to mesh the cube with increased precision around a given point.

Copyright © EDF R&D 2014.
This tutorial is a part of the EDF internal training course; it does not describe a real use case.

Sample start Python script

Create a new script (*.py) and initialize the SALOME modules GEOM and SMESH

import salome
salome.salome_init()
import GEOM
from salome.geom import geomBuilder
geompy = geomBuilder.New(salome.myStudy)
import SMESH
from salome.smesh import smeshBuilder
smesh = smeshBuilder.New(salome.myStudy)
import math

The script is executed with command File > Load Script, the objects are displayed in the GUI.

Geometry

The TUI documentation of GEOM module is available in SALOME via the menu Help -> Geometry module -> User's guide.

The section «Python Interface geomBuilder.py» describes all functions available from Python, TUI Scripts provide examples of these functions usage and some practical use cases.

We are going to parameterize the box using only its edge (Python Variable Python Arete)

As described in the SALOME documentation, execute the following operations using only scripts:

Create Arete Variable = 100

Arete=100

Create 8 points corresponding to the box vertices and its centre (Origine = (0,0,0), Diag=(Arete,Arete,Arete,))

pnt1 = geompy.MakeVertex (0,0,0)
pnt2 = geompy.MakeVertex (Arete,0,0)
pnt3 = geompy.MakeVertex (Arete,Arete,0)
pnt4 = geompy.MakeVertex (0,Arete,0)
pnt5 = geompy.MakeVertex (Arete,Arete,Arete)
pnt6 = geompy.MakeVertex (0,Arete,Arete)
pnt7 = geompy.MakeVertex (0,0,Arete)
pnt8 = geompy.MakeVertex (Arete,0,Arete)
pnt_center = geompy.MakeVertex (Arete/2,Arete/2,Arete/2)

geompy.addToStudy(pnt1, "pnt1")
geompy.addToStudy(pnt2, "pnt2")
geompy.addToStudy(pnt3, "pnt3")
geompy.addToStudy(pnt4, "pnt4")
geompy.addToStudy(pnt5, "pnt5")
geompy.addToStudy(pnt6, "pnt6")
geompy.addToStudy(pnt7, "pnt7")
geompy.addToStudy(pnt8, "pnt8")
geompy.addToStudy(pnt_center, "pnt_center")

Create 4 edges which form a face

line1 = geompy.MakeEdge(pnt1, pnt2)
line2 = geompy.MakeEdge(pnt2, pnt3)
line3 = geompy.MakeEdge(pnt3, pnt4)
line4 = geompy.MakeEdge(pnt4, pnt1)
geompy.addToStudy(line1, "line1")
geompy.addToStudy(line2, "line2")
geompy.addToStudy(line3, "line3")
geompy.addToStudy(line4, "line4")

face1=geompy.MakeFaceWires([line1,line2,line3,line4], 1)
geompy.addToStudy(face1, "face1")

Create the 1^st box by 2 points

box1 = geompy.MakeBoxTwoPnt(pnt1, pnt5)
geompy.addToStudy(box1, "box1")

Create the 2^nd box by extrusion of the reference face.

box2 = geompy.MakePrism(face1, pnt1, pnt7)
geompy.addToStudy(box2, "box2")

Create 2 other faces of the box with 2 rotations of the reference face.

angle = 90 * math.pi / 180
face2 = geompy.MakeRotation(face1, line1, angle)
face3 = geompy.MakeRotation(face1, line4, angle)
geompy.addToStudy(face2, "face2")
geompy.addToStudy(face3, "face3")

Use central symmetry on 3 created faces to build 6 faces of the 3^rd box

face4 = geompy.MakeMirrorByPoint(face1, pnt_center)
face5 = geompy.MakeMirrorByPoint(face2, pnt_center)
face6 = geompy.MakeMirrorByPoint(face3, pnt_center)
geompy.addToStudy(face4, "face4")
geompy.addToStudy(face5, "face5")
geompy.addToStudy(face6, "face6")

Create the shell from 6 faces

Shell = geompy.MakeShell([face1, face2, face3,
                          face4, face5, face6])
geompy.addToStudy(Shell, "Shell")

Create the 3^rd box from shell

box3 = geompy.MakeSolid([Shell])
geompy.addToStudy(box3, "box3")

Explode the 1^rd box to reconstruct Edges.

edgeList=geompy.SubShapeAll(box1,geompy.ShapeType["EDGE"])
i=0
for edge in edgeList :
  name = geompy.SubShapeName(edge, box1)
  id_SubEdge = geompy.addToStudyInFather(box1, edge, name)
(for the strings in "for" create an offset by 2 spaces)

Create group of edges to build SubMesh.

edge1 = salome.myStudy.FindObjectByPath
        ("/Geometry/box1/Edge_6").GetObject()
edge2 = salome.myStudy.FindObjectByPath
        ("/Geometry/box1/Edge_7").GetObject()
edge3 = salome.myStudy.FindObjectByPath
        ("/Geometry/box1/Edge_12").GetObject()
group1= geompy.CreateGroup(box1,geompy.ShapeType["EDGE"])
geompy.UnionList(group1, [edge1, edge2, edge3])

Mesh

The TUI documentation of SMESH module is available in SALOME via the menu Help -> Mesh module -> User's guide.

The section « Python Interface» describes all functions available from Python, TUI Scripts provide examples of these functions and some practical use cases.

Start with the parameterization of the mesh with a 1D hypothesis Wire Discretisation.

The standard script procedure of meshing is as follows:

Definition of the geometry for meshing in 3D:

Mesh_1 = smesh.Mesh(box1)

Definition of hypotheses and algorithms 1D, 2D and 3D :

Regular_1D = Mesh_1.Segment()
Nb_Segments_1 = Regular_1D.NumberOfSegments(10)
Nb_Segments_1.SetDistrType( 0 )
Quadrangle_2D = Mesh_1.Quadrangle()
Hexa_3D = Mesh_1.Hexahedron()

Launch of the mesh computation:

isDone = Mesh_1.Compute()
if not isDone : print "Mesh is not computed"

Create Submesh on Group of Edges (group1)

Nb_Segments_2 = smesh.CreateHypothesis
                 ('NumberOfSegments', 'StdMeshersEngine')
Nb_Segments_2.SetNumberOfSegments( 10 )
Nb_Segments_2.SetScaleFactor( 0.5 )
SubMesh_1 = Mesh_1.GetSubMesh( group1, 'SubMesh_1' )
status = Mesh_1.AddHypothesis(Regular_1D, group1)
status = Mesh_1.AddHypothesis(Nb_Segments_2,group1)
isDone = Mesh_1.Compute()
if not isDone : print "Mesh is not computed"

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