Source code for convert_mesh

#!/usr/bin/env python
Convert a mesh file from one SfePy-supported format to another.


  $ ./script/ meshes/3d/cylinder.mesh new.vtk
  $ ./script/ meshes/3d/cylinder.mesh new.vtk -s2.5
  $ ./script/ meshes/3d/cylinder.mesh new.vtk -s0.5,2,1
  $ ./script/ meshes/3d/cylinder.mesh new.vtk -s0.5,2,1 -c 0
  $ ./script/ meshes/3d/cylinder.mesh new.mesh --remesh='q2/0 a1e-8 O9/7 V'
  $ ./script/ meshes/3d/cylinder.mesh new2.mesh --remesh='rq2/0 a1e-8 O9/7 V'
from __future__ import absolute_import
import sys
import os.path as op
from six.moves import range

from argparse import ArgumentParser, RawDescriptionHelpFormatter
from sfepy.base.base import nm, output
from sfepy.base.ioutils import remove_files
from sfepy.discrete.fem import Mesh, FEDomain
from sfepy.discrete.fem.meshio import output_mesh_formats, MeshIO
from sfepy.discrete.fem.mesh import fix_double_nodes
from sfepy.mesh.mesh_tools import triangulate

helps = {
    'scale' : 'scale factor (float or comma-separated list for each axis)'
    ' [default: %(default)s]',
    'center' : 'center of the output mesh (0 for origin or'
    ' comma-separated list for each axis) applied after scaling'
    ' [default: %(default)s]',
    'refine' : 'uniform refinement level [default: %(default)s]',
    'format' : 'output mesh format (overrides filename_out extension)',
    'list' : 'list supported readable/writable output mesh formats',
    'merge' : 'remove duplicate vertices',
    'tri-tetra' : 'convert elements: quad->tri, hexa->tetra',
    '2d' : 'force a 2D mesh by removing the z coordinates - assumes a 3D mesh'
    ' in the xy plane',
    'cell-dim' : 'write only cells of a given dimension,'
    ' use a comma-separated list for several values',
    'save-per-mat': 'extract cells by material id and save them into'
    ' separate mesh files with a name based on filename_out and the id'
    ' numbers (preserves original mesh vertices)',
    'remesh' : """when given, remesh the given mesh using tetgen.
      The options can be the following, separated by spaces, in this order: 1.
      "r" causes remeshing of the mesh volume - if not present the mesh surface
      is extracted and used for the volume mesh generation. 2.
      "q[<float>/<float>]" (required) - the two numbers after "q" are a maximum
      radius-edge ratio bound and a minimum dihedral angle bound. 3. "a<float>"
      (optional) - the number imposes a maximum volume constraint on all
      tetrahedra. 4. O[<0-9>/<0-7>] - the two numbers correspond to a mesh
      optimization level and a choice of optimizing operations. 5. "V"
      (optional) - if present, mesh statistics are printed. Consult the tetgen
      documentation for details.""",

def _parse_val_or_vec(option, name, parser):
    if option is not None:
                option = float(option)
            except ValueError:
                option = [float(ii) for ii in option.split(',')]
            option = nm.array(option, dtype=nm.float64, ndmin=1)
            output('bad %s! (%s)' % (name, option))

    return option

[docs]def main(): parser = ArgumentParser(description=__doc__, formatter_class=RawDescriptionHelpFormatter) parser.add_argument('-s', '--scale', metavar='scale', action='store', dest='scale', default=None, help=helps['scale']) parser.add_argument('-c', '--center', metavar='center', action='store', dest='center', default=None, help=helps['center']) parser.add_argument('-r', '--refine', metavar='level', action='store', type=int, dest='refine', default=0, help=helps['refine']) parser.add_argument('-f', '--format', metavar='format', action='store', type=str, dest='format', default=None, help=helps['format']) parser.add_argument('-l', '--list', action='store_true', dest='list', help=helps['list']) parser.add_argument('-m', '--merge', action='store_true', dest='merge', help=helps['merge']) parser.add_argument('-t', '--tri-tetra', action='store_true', dest='tri_tetra', help=helps['tri-tetra']) parser.add_argument('-2', '--2d', action='store_true', dest='force_2d', help=helps['2d']) parser.add_argument('-d', '--cell-dim', metavar='cell_dim', action='store', dest='cell_dim', default=None, help=helps['cell-dim']) parser.add_argument('--save-per-mat', action='store_true', dest='save_per_mat', help=helps['save-per-mat']) parser.add_argument('--remesh', metavar='options', action='store', dest='remesh', default=None, help=helps['remesh']) parser.add_argument('filename_in') parser.add_argument('filename_out') options = parser.parse_args() if options.list: output('Supported readable mesh formats:') output('--------------------------------') output_mesh_formats('r') output('') output('Supported writable mesh formats:') output('--------------------------------') output_mesh_formats('w') sys.exit(0) scale = _parse_val_or_vec(options.scale, 'scale', parser) center = _parse_val_or_vec(, 'center', parser) cell_dim = _parse_val_or_vec(options.cell_dim, 'cell_dim', parser) filename_in = options.filename_in filename_out = options.filename_out if options.remesh: import tempfile import shlex import subprocess dirname = tempfile.mkdtemp() is_surface = options.remesh.startswith('q') if is_surface: mesh = Mesh.from_file(filename_in) domain = FEDomain(, mesh) region = domain.create_region('surf', 'vertices of surface', 'facet') surf_mesh = Mesh.from_region(region, mesh, localize=True, is_surface=True) filename = op.join(dirname, 'surf.mesh') surf_mesh.write(filename, io='auto') else: import shutil shutil.copy(filename_in, dirname) filename = op.join(dirname, op.basename(filename_in)) qopts = ''.join(options.remesh.split()) # Remove spaces. command = 'tetgen -BFENkACp%s %s' % (qopts, filename) args = shlex.split(command) root, ext = op.splitext(filename) mesh = Mesh.from_file(root + '.1.vtk') remove_files(dirname) else: mesh = Mesh.from_file(filename_in) if cell_dim is not None: cell_dim = [int(ii) for ii in cell_dim] data = list(mesh._get_io_data(cell_dim_only=cell_dim)) mesh = Mesh.from_data(, *data) if options.force_2d: data = list(mesh._get_io_data(cell_dim_only=2)) data[0] = data[0][:, :2] mesh = Mesh.from_data(, *data) if scale is not None: if len(scale) == 1: tr = nm.eye(mesh.dim, dtype=nm.float64) * scale elif len(scale) == mesh.dim: tr = nm.diag(scale) else: raise ValueError('bad scale! (%s)' % scale) mesh.transform_coors(tr) if center is not None: cc = 0.5 * mesh.get_bounding_box().sum(0) shift = center - cc tr = nm.c_[nm.eye(mesh.dim, dtype=nm.float64), shift[:, None]] mesh.transform_coors(tr) if options.refine > 0: domain = FEDomain(, mesh) output('initial mesh: %d nodes %d elements' % (domain.shape.n_nod, domain.shape.n_el)) for ii in range(options.refine): output('refine %d...' % ii) domain = domain.refine() output('... %d nodes %d elements' % (domain.shape.n_nod, domain.shape.n_el)) mesh = domain.mesh if options.tri_tetra > 0: mesh = triangulate(mesh, verbose=True) if options.merge: desc = mesh.descs[0] coor, ngroups, conns = fix_double_nodes(mesh.coors, mesh.cmesh.vertex_groups, mesh.get_conn(desc)) mesh = Mesh.from_data( + '_merged', coor, ngroups, [conns], [mesh.cmesh.cell_groups], [desc]) if options.save_per_mat: desc = mesh.descs[0] conns, cgroups = mesh.get_conn(desc), mesh.cmesh.cell_groups coors, ngroups = mesh.coors, mesh.cmesh.vertex_groups mat_ids = nm.unique(cgroups) for mat_id in mat_ids: idxs = nm.where(cgroups == mat_id)[0] imesh = Mesh.from_data( + '_matid_%d' % mat_id, coors, ngroups, [conns[idxs]], [cgroups[idxs]], [desc]) fbase, fext = op.splitext(filename_out) ifilename_out = '%s_matid_%d%s' % (fbase, mat_id, fext) output('writing %s...' % ifilename_out) imesh.write(ifilename_out, file_format=options.format) output('...done') output('writing %s...' % filename_out) mesh.write(filename_out, file_format=options.format, binary=False) output('...done')
if __name__ == '__main__': main()