Mod: improved meshing submodule

New: netgen neutral format conversion
Mod: updated desc
This commit is contained in:
L-Nafaryus 2022-01-22 00:07:22 +05:00
parent 7dce03e97a
commit ac9e938a50
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6 changed files with 471 additions and 95 deletions

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@ -8,5 +8,5 @@
"python.linting.enabled": true,
"python.linting.pylintEnabled": false,
"python.linting.flake8Enabled": true,
"python.linting.flake8Args": ["--ignore=E402,E251,E501,E201,E202,W293,W291", "--verbose"]
"python.linting.flake8Args": ["--ignore=E402,E251,E501,E201,E202,W293,W291,W504", "--verbose"]
}

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@ -2,4 +2,16 @@
# This file is part of anisotropy.
# License: GNU GPL version 3, see the file "LICENSE" for details.
from . import utils
from . import conversion
from . import metrics
from .mesh import Mesh
__all__ = [
"utils",
"conversion",
"metrics",
"Mesh"
]

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@ -0,0 +1,145 @@
from numpy import ndarray
from os import PathLike
import numpy as np
from pathlib import Path
from . import utils
def write_neutral(
points: ndarray,
cells: list[utils.CellBlock],
dim: int,
filename: PathLike
):
"""Write mesh to the netgen file (Neutral format [.mesh]).
:param points:
Array of points.
:param cells:
List of cell blocks.
:param dim:
Dimension of the mesh.
:param filename:
Path of the file.
"""
precision = "6f"
floatValue = "{value:>{width}." + precision + "}"
intValue = "{value:>{width}}"
outfile = open(Path(filename).resolve(), "w")
# write points
outfile.write(str(len(points)) + "\n")
for n in range(len(points)):
point = points[n]
outfile.write(floatValue.format(value = point[0], width = 10) + " ")
outfile.write(floatValue.format(value = point[1], width = 9) + " ")
if dim == 3:
outfile.write(floatValue.format(value = point[2], width = 9) + " ")
outfile.write("\n")
# write volume cells
if dim == 3:
count = sum([ len(cell.data) for cell in cells if cell.dim == 3])
outfile.write(str(count) + "\n")
for cellBlock in cells:
if cellBlock.dim == 3:
for cell in cellBlock.data:
outfile.write(intValue.format(value = 1, width = 4))
for pointId in cell:
outfile.write(" ")
# shift id up, in netgen it starts from one
outfile.write(intValue.format(value = pointId + 1, width = 8))
outfile.write("\n")
# write faces
count = sum([ len(cell.data) for cell in cells if cell.dim == 2])
outfile.write(str(count) + "\n")
for cellBlock in cells:
if cellBlock.dim == 2:
for index, cell in zip(cellBlock.indices, cellBlock.data):
outfile.write(intValue.format(value = index, width = 4) + " ")
for pointId in cell:
outfile.write(" ")
# shift id up, in netgen it starts from one
outfile.write(intValue.format(value = pointId + 1, width = 8))
outfile.write("\n")
# write segments
# important?
def read_neutral(filename: PathLike) -> tuple[list, list]:
"""Read mesh from netgen file (Neutral format [.mesh]).
:param filename:
Path of the file.
:return:
List of points and list of cell blocks.
"""
infile = open(Path(filename).resolve(), "r")
# read points from file, starts with single integer
npoints = int(infile.readline())
points = []
for n in range(npoints):
points.append(np.fromstring(infile.readline(), dtype = float, sep = " "))
# dimension
dim = None if len(points) == 0 else points[0].size
# read volume cells
nvolumes = int(infile.readline())
volume_indices = []
volumes = []
for n in range(nvolumes):
data = np.fromstring(infile.readline(), dtype = int, sep = " ")
volume_indices.append(data[0])
# shift node indices down, in netgen it starts from one, need from zero
volumes.append(data[1: ] - 1)
# read surface cells
nsurfaces = int(infile.readline())
surface_indices = []
surfaces = []
for n in range(nsurfaces):
data = np.fromstring(infile.readline(), dtype = int, sep = " ")
surface_indices.append(data[0])
# shift node indices down, in netgen it starts from one, need from zero
surfaces.append(data[1: ] - 1)
# read segment cells
# important?
# write data to object
points = np.asarray(points)
cells = []
if len(volumes) > 0:
cells += utils.collect_cells(volumes, 3, volume_indices)
if len(surfaces) > 0:
cellBlocks = utils.collect_cells(surfaces, 2, surface_indices)
if dim == 3:
for cellBlock in cellBlocks:
cellBlock.is_boundary = True
cells += cellBlocks
return points, cells

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@ -2,28 +2,35 @@
# This file is part of anisotropy.
# License: GNU GPL version 3, see the file "LICENSE" for details.
from netgen.occ import OCCGeometry
from netgen import meshing
import numpy
from numpy import array, ndarray, linalg
import os
from .utils import extractNetgenPoints, extractNetgenCells
from . import metrics
from __future__ import annotations
from numpy import ndarray
from os import PathLike
import numpy as np
import netgen.occ as ng_occ
import netgen.meshing as ng_meshing
import meshio
import pathlib
from . import utils
from . import metrics
from . import conversion
class NoGeometrySpecified(Exception):
def __init__(self, msg):
super().__init__(self, msg)
pass
class NotSupportedMeshFormat(Exception):
def __init__(self, msg):
super().__init__(self, msg)
"""Exception for not supported mesh format IO operations.
"""
pass
class MeshingParameters(object):
class MeshingParameters:
def __init__(self, **kwargs):
"""A MeshingParameters object contains parameters for netgen mesher.
"""
self.preset(2, **kwargs)
def preset(self, key: int, **kwargs):
@ -36,96 +43,170 @@ class MeshingParameters(object):
3: fine
4: very_fine
"""
self.maxh = kwargs.get("maxh", 0.2)
self.curvaturesafety = kwargs.get("curvaturesafety", [1, 1.5, 2, 3, 5][key])
self.segmentsperedge = kwargs.get("segmentsperedge", [0.3, 0.5, 1, 2, 3][key])
self.grading = kwargs.get("grading", [0.7, 0.5, 0.3, 0.2, 0.1][key])
self.chartdistfac = kwargs.get("chartdistfac", [0.8, 1, 1.5, 2, 5][key])
self.linelengthfac = kwargs.get("linelengthfac", [0.2, 0.35, 0.5, 1.5, 3][key])
self.closeedgefac = kwargs.get("closeedgefac", [0.5, 1, 2, 3.5, 5][key])
self.minedgelen = kwargs.get("minedgelen", [0.002, 0.02, 0.2, 1.0, 2.0][key])
self.surfmeshcurvfac = kwargs.get("surfmeshcurvfac", [1, 1.5, 2, 3, 5.0][key])
self.optsteps2d = kwargs.get("optsteps2d", 5)
self.optsteps3d = kwargs.get("optsetps3d", 5)
self.__dict__.update(kwargs)
self.maxh = kwargs.get("maxh", 0.2)
self.curvaturesafety = kwargs.get("curvaturesafety", [1, 1.5, 2, 3, 5][key])
self.segmentsperedge = kwargs.get("segmentsperedge", [0.3, 0.5, 1, 2, 3][key])
self.grading = kwargs.get("grading", [0.7, 0.5, 0.3, 0.2, 0.1][key])
self.chartdistfac = kwargs.get("chartdistfac", [0.8, 1, 1.5, 2, 5][key])
self.linelengthfac = kwargs.get("linelengthfac", [0.2, 0.35, 0.5, 1.5, 3][key])
self.closeedgefac = kwargs.get("closeedgefac", [0.5, 1, 2, 3.5, 5][key])
self.minedgelen = kwargs.get("minedgelen", [0.002, 0.02, 0.2, 1.0, 2.0][key])
self.surfmeshcurvfac = kwargs.get("surfmeshcurvfac", [1, 1.5, 2, 3, 5.0][key])
self.optsteps2d = kwargs.get("optsteps2d", 5)
self.optsteps3d = kwargs.get("optsetps3d", 5)
return self
def get(self) -> meshing.MeshingParameters:
return meshing.MeshingParameters(**self.__dict__)
def get(self) -> ng_meshing.MeshingParameters:
return ng_meshing.MeshingParameters(**self.__dict__)
def __repr__(self):
return str(self.__dict__)
items = [ f"{ key }: { val }" for key, val in self.__dict__.items() ]
return "<MeshingParameters, " + ", ".join(items) + ">"
class Mesh(object):
class Mesh:
def __init__(self, shape = None):
"""A Mesh object contains a mesh
:param shape:
OCC shape.
"""
self.shape = shape
self.mesh = None
self.points = []
self.cells = []
self.boundary = []
self._dim = None
@property
def geometry(self):
return OCCGeometry(self.shape)
def dim(self) -> float | None:
"""Mesh dimension.
def generate(self, parameters: MeshingParameters = None, refineSteps: int = 0, scale: float = 0):
:return:
float or None if mesh contains no points.
"""
return None if len(self.points) == 0 else self.points[0].size
@property
def geometry(self) -> ng_occ.OCCGeometry:
"""Netgen OCCGeometry object.
:return:
OCCGeometry object that can be used for meshing
or None if shape is not defined.
"""
return ng_occ.OCCGeometry(self.shape) if self.shape else None
def generate(
self,
parameters: ng_meshing.MeshingParameters = None,
refineSteps: int = 0,
refineOptimize: bool = True,
scale: float = 0
):
"""Generate mesh using netgen mesher on occ geometry.
:param parameters:
Meshing parameters object.
:param refineSteps:
Refine mesh after main meshing.
:param refineOptimize:
If True, optimize surface and volume mesh after each refine step.
:param scale:
Scale mesh after all operations.
"""
if not self.geometry:
raise NoGeometrySpecified("Cannot build mesh without geometry")
parameters = parameters or MeshingParameters()
# generate volume mesh
mesh = self.geometry.GenerateMesh(parameters.get())
if refineSteps > 0:
for n in range(refineSteps):
mesh.Refine()
mesh.OptimizeMesh2d(parameters)
mesh.OptimizeVolumeMesh(parameters)
# optimize surface and volume mesh
if refineOptimize:
mesh.OptimizeMesh2d(parameters.get())
mesh.OptimizeVolumeMesh(parameters.get())
if scale > 0:
mesh.Scale(scale)
self.points = extractNetgenPoints(mesh)
self.points = utils.extract_netgen_points(mesh)
self.cells = []
for dim in range(4):
self.cells.extend(extractNetgenCells(dim, mesh))
if mesh.dim == 3:
volume_cells, volume_indices = utils.extract_netgen_cells(mesh, 3)
self.cells += utils.collect_cells(volume_cells, 3, volume_indices)
surface_cells, surface_indices = utils.extract_netgen_cells(mesh, 2)
cell_blocks = utils.collect_cells(surface_cells, 3, surface_indices)
for cellBlock in cell_blocks:
cellBlock.is_boundary = True
self.cells += cell_blocks
# TODO: dim == 2
return self
def read(self, filename: str):
"""Import a mesh.
"""Import a mesh from the file.
:param filename:
Name of the mesh file.
"""
mesh = meshio.read(filename)
Path of the file.
"""
path = pathlib.Path(filename).resolve()
ext = path.suffix[1: ]
self.points = mesh.points
self.cells = mesh.cells
# Force netgen neutral format
if ext == "mesh":
self.points, self.cells = conversion.read_neutral(path)
else:
mesh = meshio.read(path)
self.points = mesh.points
self.cells = mesh.cells
return self
def write(self, filename: str):
"""Export a mesh.
def write(self, filename: PathLike):
"""Export mesh to the file.
:param filename:
Name of the file to store the given mesh in.
"""
mesh = meshio.Mesh(self.points, self.cells)
mesh.write(filename)
Path of the file to store the given mesh in.
"""
path = pathlib.Path(filename).resolve()
ext = path.suffix[1: ]
# Force netgen neutral format
if ext == "mesh":
conversion.write_neutral(self.points, self.cells, self.dim, path)
else:
mesh = meshio.Mesh(self.points, self.cells)
mesh.write(path)
@property
def volumes(self) -> list[ndarray]:
def volumes(self) -> list[ndarray]: # delete?
"""Volumes.
:return:
List of points.
"""
points = []
for cellBlock in self.cells:
if cellBlock.dim == 3:
points.extend([ *self.points[cellBlock.data] ])
points += [ *self.points[cellBlock.data] ]
return points
@ -136,15 +217,19 @@ class Mesh(object):
:return:
Volume.
"""
return sum([ metrics.volume(cell) for cell in self.volumes ])
return np.sum([ metrics.volume(cell) for cell in self.volumes ])
@property
def faces(self) -> list[ndarray]:
def faces(self) -> list[ndarray]: # delete?
"""Boundary faces.
:return:
List of boundary faces.
"""
points = []
for cellBlock in self.cells:
if cellBlock.dim == 2:
points.extend([ *self.points[cellBlock.data] ])
if cellBlock.dim == 2 and cellBlock.is_boundary:
points += [ *self.points[cellBlock.data] ]
return points

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@ -2,18 +2,42 @@
# This file is part of anisotropy.
# License: GNU GPL version 3, see the file "LICENSE" for details.
import numpy
import numpy as np
from numpy import ndarray
from numpy import linalg
from .utils import detectCellType
from . import utils
def volume(points: ndarray) -> ndarray:
cellType = detectCellType(3, len(points))
"""Volume of the cell.
:param points:
Array of points that represents volumetric cell.
:return:
Volume.
"""
cellType = utils.cell_type(3, len(points))
if cellType == "tetra":
return 1 / 6 * linalg.det(numpy.append(points.transpose(), numpy.array([[1, 1, 1, 1]]), axis = 0))
return 1 / 6 * np.linalg.det(np.append(points.transpose(), np.array([[1, 1, 1, 1]]), axis = 0))
else:
raise Exception(f"Not supported cell type '{ cellType }'")
def area(points: ndarray) -> ndarray:
"""Area of the cell.
:param points:
Array of points that represents surface cell.
:return:
Area.
"""
cellType = utils.cell_type(2, len(points))
vecs = np.roll(points, shift = -1, axis = 0) - points
if cellType == "triangle":
return 0.5 * np.abs(np.cross(*vecs[ :-1]))
else:
raise Exception(f"Not supported cell type '{ cellType }'")

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@ -1,17 +1,64 @@
from __future__ import annotations
from netgen import meshing
from meshio._mesh import topological_dimension
from meshio._common import num_nodes_per_cell
from numpy import array, asarray, ndarray
from numpy import ndarray
def detectCellType(dimension: int, num_nodes: int):
for dim in topological_dimension.keys():
for num in num_nodes_per_cell.keys():
if topological_dimension[dim] == dimension and num_nodes_per_cell[num] == num_nodes and dim == num:
import numpy as np
import netgen.meshing as ng_meshing
import meshio
topo_dim = meshio._mesh.topological_dimension
cell_nodes = meshio._common.num_nodes_per_cell
def cell_type(dimension: int, num_nodes: int) -> str | None:
"""Detect a cell topology type.
:param dimension:
Cell dimension.
:param num_nodes:
Number of nodes in the cell.
:return:
Cell type or None if cell type if not supported.
"""
for dim in topo_dim.keys():
for num in cell_nodes.keys():
if (
topo_dim[dim] == dimension and
cell_nodes[num] == num_nodes and
dim == num
):
return dim
return None
class CellBlock:
def __init__(self, cellType: str, data: list | ndarray, tags: list[str] | None = None):
def __init__(
self,
cellType: str,
data: list | ndarray,
tags: list[str] = [],
indices: list | ndarray = [],
is_boundary: bool = False,
names: list[str] = []
):
"""A CellBlock object contains cells information of the same type.
:param cellType:
Type of the cell.
:param data:
Array of cells.
:param tags:
Some cell tags.
:param indices:
Array of indices of cells. Must be the same length as data length.
Usefull for detecting boundary faces, etc.
:param is_boundary:
Flag that cells are not internal.
:param names:
Array of names of cells. Must be the same length as data length.
Usefull for detecting boundary faces, etc.
"""
self.type = cellType
self.data = data
@ -19,10 +66,13 @@ class CellBlock:
self.dim = 3
else:
self.data = asarray(self.data)
self.dim = topological_dimension[cellType]
self.data = np.asarray(self.data)
self.dim = topo_dim[cellType]
self.tags = [] if tags is None else tags
self.tags = tags
self.indices = np.asarray(indices)
self.is_boundary = is_boundary
self.names = names
def __repr__(self):
items = [
@ -36,12 +86,80 @@ class CellBlock:
def __len__(self):
return len(self.data)
def extractNetgenPoints(mesh: meshing.Mesh) -> ndarray:
return array([ point.p for point in mesh.Points() ], dtype = float)
def collect_cells(cells: list, dim: int, indices: list | ndarray = None, cellType: str = None) -> list[CellBlock]:
"""Collect cell blocks from a list of cells.
:param cells:
List of cells.
:param dim:
Cell dimension.
:param indices:
List of cell indices. Must be the same length as list of cells.
:return:
List of cell blocks.
"""
cellBlocks = []
if indices is not None:
assert len(cells) == len(indices), "cells and indices arrays must be the same length"
for n, cell in enumerate(cells):
cellType = cellType or cell_type(dim, len(cell))
index = indices[n] if indices else None
is_added = False
# update cell block
for cellBlock in cellBlocks:
if cellBlock.type == cellType:
cellBlock.data += [ cell ]
if index:
cellBlock.indices.append(index)
is_added = True
# or create new
if not is_added:
cellBlock = CellBlock(cellType, [])
cellBlock.data = [ cell ]
if index:
cellBlock.indices = [ index ]
cellBlocks.append(cellBlock)
# convert arrays to numpy
for cellBlock in cellBlocks:
cellBlock.data = np.asarray(cellBlock.data)
cellBlock.indices = np.asarray(cellBlock.indices)
return cellBlocks
def extractNetgenCells(dim: int, mesh: meshing.Mesh) -> list[CellBlock]:
cellsDict = {}
def extract_netgen_points(mesh: ng_meshing.Mesh) -> ndarray:
"""Extract points from netgen mesh object.
:param mesh:
Netgen mesh object.
:return:
Array of points.
"""
return np.array([ point.p for point in mesh.Points() ], dtype = float)
def extract_netgen_cells(mesh: ng_meshing.Mesh, dim: int) -> tuple[list, list]:
"""Extract cells from netgen mesh according to cell dimension.
:param mesh:
Netgen mesh object.
:param dim:
Cell dimension.
:return:
List of cells and list of indices.
"""
cells = []
indices = []
elements = {
0: mesh.Elements0D(),
1: mesh.Elements1D(),
@ -49,20 +167,12 @@ def extractNetgenCells(dim: int, mesh: meshing.Mesh) -> list[CellBlock]:
3: mesh.Elements3D()
}[dim]
if len(elements) == 0:
return []
for cell in elements:
cellType = detectCellType(dim, len(cell.points))
# shift indicies, they should start from zero
cellNew = array([ pointId.nr for pointId in cell.points ], dtype = int) - 1
if cellsDict.get(cellType):
cellsDict[cellType].append(cellNew)
else:
cellsDict[cellType] = [ cellNew ]
cells = [ CellBlock(key, value) for key, value in cellsDict.items() ]
return cells
if len(elements) > 0:
for cell in elements:
# shift nodes values, they should start from zero
nodes = np.array([ node.nr for node in cell.points ], dtype = int) - 1
cells.append(nodes)
indices.append(cell.index)
return cells, indices