u7.03.03 Méthodes Python de pilotage de GMSH#
Résumé:
Ce document présente le superviseur permettant de piloter GMSH depuis Python, et donc depuis le fichier de commandes Aster.
Ce superviseur produit tout type de maillages 2D en utilisant le logiciel GMSH (https://gmsh.info). Il est notamment utilisé dans Aster par l’outil de post-traitement interactif STANLEY afin de générer des éléments de maillage pour le post-traitement, mais peut être étendu à d’autres applications: maillage paramétrique, remaillage, etc.
Liste des fonctions disponibles#
La liste des fonctions est extraite directement du source, sup_gmsh.py, ce qui explique qu’elle soit en anglais.
Classe générique pour les objets géométriques#
class Geometric :
private attribute
parameters : dictionnary of the attributes (except relation and parameters itself)
see __getattr__ and __setattr__
Attributes
num : index among gmsh objects
md : mesh descriptor
mesh : related mesh object
relation : model object in case of coincidence
Public methods
Is_point : return true is the object inherits of the Point class
Is_line : return true is the object inherits of the Line class
Is_surface : return true is the object inherits of the Surface class
Is_volume : return true is the object inherits of the Volume class
Is_same_dimension : return true is both objects are of the same dimension
(point, line, surface or volume)
in -> object to compare to self
Duplicate : duplicate an object and base its mesh_descriptor
on the mesh_descriptor of the model
Coincide : assert that an object is coincident with a model one
All the attributes are then automatically read from
the model object (see __setattr__ and __getattr__).
in -> model object
Private method
Root :
Provides the root object of an object, ie the object itself if there is no relation
or the deepest model in case of relation.
Geometric_coincide : check if a geometrical coincidence is possible
return information about the coincidence, false else.
in -> model object
Deep_coincide : proceed recursively to ensure coincidence of the relevant sub-objects
in -> model object
in -> correspond (information returned by Geometric_coincide)
__setattr__ : distinguish two sets of attributes
relation (to express a relation with a model object in case of coincidence)
all the other attributes which are stored in the dictionnary parameters
instead of the usual __dict__ if there is no relation (see Coincide)
and in the model object if there is a coincidence
__getattr__ : if the object is related (relation <> None) the attribute is read
in the model object. Else, it is read in the current object, actually
in the dictionnary parameters (see __setattr__)
Thanks to these two overloaded methods, the access to the attributes is usual if
there is no relation whereas the attributes of the model object are accessed
transparently if there is a relation.
__cmp__ :
The comparison of two objects involves possible coincidence. It is no more the object ids
that are compared but the object roots (.relation if any).
Gmsh : produce the source code for Gmsh
in -> mesh
Gmsh_send : send a line code to the gmsh interpreter
in -> line_code (string)
Intermediate_meshing : produce the source code for the intermediate objects
in -> mesh
Object meshing : produce the source code for the current object
var -> object number (modified if several objects are created)
Fonctions pour les objets POINT#
class Point(Geometric) :
Public methods
__init__ :
in -> coordinates (the 3rd is zero by default)
Size : set the size of the neighbouring elements
in -> size
Attractor : define the point as an attractor
in -> scale_x : size amplification factor in the x-direction
in -> scale_y : size amplification factor in the y-direction
in -> distance: influence distance for the perturbation
Attributes
coor : coordinates
size : neighbouring element size
attractor : parameters of the attractor
Fonctions pour les objets LIGNE#
class Line(Geometric) :
LINE OBJECT
Public methods
Attractor : define the point as an attractor
in -> scale_x : size amplification factor in the x-direction
in -> scale_y : size amplification factor in the y-direction
in -> distance: influence distance for the perturbation
class Circle(Line) :
CIRCLE OBJECT
def Curve(l_x,l_y,l_z=None) :
CURVE OBJECT (in -> list of points)
Fonctions pour les objets SURFACE#
class Surface(Geometric) :
SURFACE OBJECT (inherit from the Geometric class)
Public methods
__init__ :
in -> lines : external bounday of the surface (lines should be connected)
Holes : set the internal holes (surfaces)
in -> holes : list of holes
Boundary : checks that the boundary is a closed loop and returns the orientation of the edges
Ruled : declare the surface is a ruled one
Translate : translate the surface
in -> tran : (numpy) vector of translation
Recombine : recombine the surface (try to mesh with quadrangles instead of triangles)
Transfinite : Declare the mesh to be transfinite
Attributes
lines : list of external boundary lines
holes : list of internal holes (surfaces)
ruled : indicates (false or true) if the surface is a ruled surface
loops : list of boundary (external and internal) loops (computed when meshing)
Fonctions pour les opérations sur les maillages#
class Mesh_Descriptor :
Attributes
relation Another mesh descriptor provides the mesh parameters
parameters dictionnary of the mesh parameters
size Point size
transfinite Transfinite mesh (0 or 1)
number Number of elements along a line (transfinite)
progression Progression of element size (transfinite)
recombine Recombine mesh or not
Specific access :
md.parameter_name = xxx -> the relation is destroyed (set to None)
xxx = md.parameter_name -> if there is a relation, the effective
parameter is looked for recursively
Deep copying : a relation is set to the model instead of a true copy
class Mesh :
def __init__(self, algo = 2, gmsh=”gmsh”) :
def Physical(self, name, *l_obj) : creation of Physical (GMSH object)
def Save(self, file = “fort.geo”) : save the geo file
def View(self) : launch GMSH with the current geo file
def Create(self, file = “fort.19”) : save the geo file and create the msh file
def Name(self, MA, CREA_GROUP_NO) : create the group_ma and/or the group_no
def LIRE_GMSH(self,
UNITE_GMSH= 19,
UNITE_MAILLAGE= 20,
MODI_QUAD= “NON”,
CREA_GROUP_NO= “OUI”
) :
Lecture du maillage (format Aster) à partir de sa définition (format sup_gmsh)
UNITE_GMSH= Numéro d’unité logique pour le fichier msh
UNITE_MAILLAGE = Numéro d’unité logique pour le fichier mail
MODI_QUAD= “OUI” si line->quad, “NON” sinon
CREA_GROUP_NO= “OUI” si on crée les GROUP_NO, “NON” sinon
Fonctions pour les transformations géométriques#
def VectorProduct(u,v) :
def VectorNorm(u) :
class Rotation :
in -> A,C,B