# Copyright (c) 2012-2025, OpenGeoSys Community (http://www.opengeosys.org)
# Distributed under a Modified BSD License.
# See accompanying file LICENSE.txt or
# http://www.opengeosys.org/project/license
#
import tempfile
from collections.abc import Callable
from pathlib import Path
import numpy as np
import pyvista as pv
[docs]
class RegionSet:
"""
A class representing a set of regions composed of subsets, each identified by MaterialID.
The RegionSet class represents a collection of regions, where each region is composed of
subsets. Each subset within a region is uniquely identified by "MaterialID".
"""
[docs]
def __init__(self, input: Path | pv.UnstructuredGrid):
if type(input) is Path:
self.filename = input
self.mesh = None
else:
self.filename = Path(tempfile.mkstemp(".vtu", "region_set")[1])
self.mesh = input
[docs]
def box_boundaries(self) -> tuple[pv.UnstructuredGrid, ...]:
"""
Retrieve the boundaries of the mesh in local coordinate system (u, v, w).
This function extracts the boundaries of the mesh along the u, v, and w directions
of the local coordinate system. The u-axis corresponds to the x-coordinate, the v-axis
corresponds to the y-coordinate, and the w-axis corresponds to the z-coordinate.
:returns: A tuple (u_min, u_max, v_min, v_max, w_min, w_max)
representing the boundaries of the mesh in the local
coordinate system.
notes:
- If the original mesh was created from boundaries, this function returns the original boundaries.
- The returned boundaries adhere to the definition of [Pyvista Box](https://docs.pyvista.org/version/stable/api/utilities/_autosummary/pyvista.Box.html).
example:
mesh = ...
u_min, u_max, v_min, v_max, w_min, w_max = mesh.box_boundaries()
"""
assert isinstance(self.mesh, pv.UnstructuredGrid)
surface = self.mesh.extract_surface()
u_max = to_boundary(surface, lambda normals: normals[:, 0] > 0.5)
u_min = to_boundary(surface, lambda normals: normals[:, 0] < -0.5)
v_max = to_boundary(surface, lambda normals: normals[:, 1] > 0.5)
v_min = to_boundary(surface, lambda normals: normals[:, 1] < -0.5)
w_max = to_boundary(surface, lambda normals: normals[:, 2] > 0.5)
w_min = to_boundary(surface, lambda normals: normals[:, 2] < -0.5)
return (u_min, u_max, v_min, v_max, w_min, w_max)
[docs]
def to_boundary(
surface_mesh: pv.PolyData,
filter_condition: Callable[[np.ndarray], np.ndarray],
) -> pv.UnstructuredGrid:
"""
Extract cells from a surface mesh that meet a filter condition for normals.
This function takes a surface mesh represented by a `pv.PolyData` object and extracts
cells that match a specified filter condition based on the normals of the mesh.
:param surface_mesh: The input surface mesh.
:param filter_condition: A callable filter condition that takes an array
of normals as input and returns an array
indicating whether the condition is met.
:returns: A mesh containing only the cells that meet the filter condition.
example:
surface_mesh = ...
specific_cells = to_boundary(surface_mesh, lambda normals: [n[2] > 0.5 for n in normals])
"""
surface_mesh = surface_mesh.compute_normals(
cell_normals=True, point_normals=True
)
ids = np.arange(surface_mesh.n_cells)[
filter_condition(surface_mesh["Normals"])
]
specific_cells = surface_mesh.extract_cells(ids)
specific_cells.rename_array("vtkOriginalPointIds", "BULK_NODE_ID")
specific_cells.rename_array("vtkOriginalCellIds", "BULK_ELEMENT_ID")
specific_cells.cell_data.remove("Normals")
return specific_cells
