Triangle/TetGen interface

Some common notions

class meshpy.ForeignArray

Note that ForeignArray instances are not usually created by users, and ForeignArray is not a class name available in MeshPy. It is just used to explain the interface provided.

Almost all input and output data in MeshPy can be accessed using the ForeignArray interface. It is called “foreign” because it provides access to an area of memory accessible by a pointer managed by an outside piece of software, such as a mesh generator.

Note that ForeignArray has no append method. Instead, use ForeignArray.resize() and then set the consecutive entries of the array.

__len__()

Return the number of entries in the array. If the array is 2D (i.e. has non-1 unit), ForeignArray.__len__() only returns the length of the leading dimension. For example, for an array of points in n-dimensional space, __len__() returns the number of points.

unit

If this ForeignArray represents a two-dimensional array, such as an array of point coordinates, ForeignArray.unit() gives the size of the subordinate dimension.

For example, for an array of points in 3-dimensional space, ForeignArray.__len__() returns the number of dimensions (3).

allocated

Return a bool indicating whether storage has been allocated for this array. This is only meaningful if the size of this array is tied to that of another, see ForeignArray.setup().

resize(new_size)

Change the length of the array as returned by ForeignArray.__len__().

setup()

Set up (i.e. allocate) storage for the array. This only works on arrays whose size is tied to that of other arrays, such as an array of point markers, which necessarily has the same size as the associated array of points, if it is allocated.

deallocate()

Release any storage associated with the array.

__getitem__(index)

__setitem__(index, value)

Get and set entries in the array. If this foreign array is 2D (see ForeignArray.unit), index may be a 2-tuple of integers, as in:

points[2,1] = 17

meshpy.triangle – Triangular Meshing

class meshpy.triangle.ForeignArray

See meshpy.ForeignArray for shared documentation.

class meshpy.triangle.MeshInfo

MeshInfo objects are picklable.

points

A 2D ForeignArray of float with dimension (N,2), providing a list of points that are referred to by index from other entries of this structure.

point_attributes

If MeshInfo.number_of_point_attributes is non-zero, this is a ForeignArray of floats of point attributes.

This element’s size is tied to that of MeshInfo.points.

point_markers

ForeignArray of floats of point attributes.

This element’s size is tied to that of MeshInfo.points.

elements

element_attributes

This element’s size is tied to that of MeshInfo.elements.

element_volumes

This element’s size is tied to that of MeshInfo.elements.

neighbors

facets

facet_markers

holes

regions

faces

face_markers

normals

number_of_point_attributes

number_of_element_vertices

Defautls to 4 for linear tetrahedra. Change to 10 for second-order tetrahedra.

number_of_element_attributes

Convenient setters:

set_points(points, point_markers=None)

set_holes(points, hole_starts)

set_facets(facets, facet_markers=None)

Other functionality:

copy()

Return a duplicate copy of this object.

meshpy.triangle.subdivide_facets(subdivisions, points, facets, facet_markers)

Subdivide facets into subdivisions subfacets.

This routine is useful if you have to prohibit the insertion of Steiner points on the boundary of your triangulation to allow the mesh to conform either to itself periodically or another given mesh. In this case, you may use this routine to create the necessary resolution along the boundary in a predefined way.

subdivisions is either an int, indicating a uniform number of subdivisions throughout, or a list of the same length as facets, specifying a subdivision count for each individual facet.

points

a list of points referred to from the facets list.

facets

a list of old facets, in the form [(p1, p2), (p3,p4), …].

facet_markers

either None or a list of facet markers of the same length as facets.

Returns a tuple (new_points, new_facets), or (new_points, new_facets, new_facet_markers) if facet_markers is not None.

meshpy.triangle.build(mesh_info, verbose=False, refinement_func=None, attributes=False, volume_constraints=True, max_volume=None, allow_boundary_steiner=True, allow_volume_steiner=True, quality_meshing=True, generate_edges=None, generate_faces=False, min_angle=None)

meshpy.triangle.refine(input_p, verbose=False, refinement_func=None, quality_meshing=True, min_angle=None)

meshpy.triangle.write_gnuplot_mesh(filename, out_p, facets=False)

meshpy.tet – Tetrahedral Meshing

class meshpy.tet.ForeignArray

See meshpy.ForeignArray for shared documentation.

class meshpy.tet.Options(switches='pq', **kwargs)

Run time switches for TetGen. See the TetGen documentation for the meaning of each switch.

Using the kwargs constructor argument, all the attributes defined below can be set. This setting will occur after Options.parse_switches() is called with the switches parameter.

plc

quality

refine

coarse

metric

varvolume

fixedvolume

insertaddpoints

regionattrib

conformdel

diagnose

zeroindex

optlevel

optpasses

order

facesout

edgesout

neighout

voroout

meditview

gidview

geomview

nobound

nonodewritten

noelewritten

nofacewritten

noiterationnum

nomerge

nobisect

noflip

nojettison

steiner

fliprepair

docheck

quiet

verbose

useshelles

minratio

goodratio

minangle

goodangle

maxvolume

maxdihedral

alpha1

alpha2

alpha3

epsilon

epsilon2

parse_switches(switches)

class meshpy.tet.Polygon

vertices

class meshpy.tet.Facet

polygons

holes

class meshpy.tet.PBCGroup

facet_marker_1

facet_marker_2

point_pairs

matrix

class meshpy.tet.MeshInfo

points

point_attributes

point_metric_tensors

point_markers

elements

element_attributes

element_volumes

neighbors

facets

facet_markers

holes

regions

facet_constraints

segment_constraints

pbc_groups

faces

adjacent_elements

face_markers

edges

edge_markers

edge_adjacent_elements

Added in version 2016.1.

number_of_point_attributes

number_of_element_attributes

Convenient setters:

set_points(points, point_markers=None)

set_holes(points, hole_starts)

set_facets(facets, markers=None)

Set a list of simple, single-polygon factes. Unlike MeshInfo.set_facets_ex(), this method does not allow holes and only lets you use a single polygon per facet.

facets

a list of facets, where each facet is a single polygons, represented by a list of point indices.

markers

Either None or a list of integers of the same length as facets. Each integer is the facet marker assigned to its corresponding facet.

Note

When the above says “list”, any repeatable iterable also accepted instead.

set_facets_ex(facets, facet_holestarts=None, markers=None)

Set a list of complicated facets. Unlike MeshInfo.set_facets(), this method allows holes and multiple polygons per facet.

facets

a list of facets, where each facet is a list of polygons, and each polygon is represented by a list of point indices.

facet_holestarts

Either None or a list of hole starting points for each facet. Each facet may have several hole starting points. The mesh generator starts “eating” a hole into the facet at each starting point and continues until it hits a polygon specified in this facet’s record in facets.

markers

Either None or a list of integers of the same length as facets. Each integer is the facet marker assigned to its corresponding facet.

Note

When the above says “list”, any repeatable iterable also accepted instead.

Other functionality:

face_vertex_indices_to_face_marker

dump()

write_vtk(filename)

TetGen-provided loading and saving:

save_nodes(filename)

save_elements(filename)

save_faces(filename)

save_edges(filename)

save_neighbors(filename)

save_poly(filename)

load_node(filename)

load_pbc(filename)

load_var(filename)

load_mtr(filename)

load_poly(filename)

load_ply(filename)

load_stl(filename)

load_medit(filename)

load_plc(filename)

load_tetmesh(filename)

meshpy.tet.build(mesh_info, options=Options('pq'), verbose=False, attributes=False, volume_constraints=False, max_volume=None, diagnose=False, insert_points=None, mesh_order=None)

Parameters:

insert_points – a MeshInfo object specifying additional points to be inserted