Skip to content

MeshGenerator

Mesh generator class.

Attributes:

Name Type Description
surfaces list[dict]

List of surface dictionaries with mesh information.
Source code in pymesh/mesh/mesh_generator.py 
class MeshGenerator:
    """Mesh generator class.

    Attributes:
        surfaces: List of surface dictionaries with mesh information.
    """

    surfaces: list[dict] = []
    """List of surface dictionaries with mesh information.

    Each surface dictionary follows the structure:

    .. code-block:: python3
        surface = {
            "path": Callable[[float], NDArray3],
            "flipped_normal": bool,
            "num_points": tuple[int],
            "distributions": tuple[MeshDistribution],
        }

    Note:
        Above code block works in Visual Studio Code.
    """

    def add_surface(
        self,
        surface: Surface,
        density_u: int | float = 0.2,
        density_w: int | float = 0.2,
        distribution_u: MeshDistribution = LinearDistribution(),
        distribution_w: MeshDistribution = LinearDistribution(),
    ) -> None:
        """Adds a surface to the mesh.

        Args:
            surface: Surface object to be added.
            density_u: Panel density along the u dimension.
                Integer values represent the number of panels,
                while float values represent panel size.
            density_w: Panel density along the w dimension.
                Integer values represent the number of panels,
                while float values represent panel size.
            distribution_u: Distribution type along the u dimension.
            distribution_w: Distribution type along the w dimension.

        Examples:
            Initialize a mesh and add a surface with two panels (linearly distributed
            by default) along the u dimension and a panel length of 0.1 units along
            the w dimension. These panels are distributed exponentially.

            >>> surface = PlaneSurface(Point(0, 0, 0), Point(1, 0, 0), Point(0, 1, 0))
            >>> dist_exp = ExponentialDistribution()
            >>> mesh = MeshGenerator()
            >>> mesh.add_surface(surface, density_u=2, density_w=0.1, distribution_w=dist_exp)

            The user is referred to [pymesh.mesh.mesh_distributions][] for more
            information on distribution_u and distribution_w options.

        Note:
            Above example code block style works with MkDocs, but does not look nice
            in Visual Studio Code.
        """
        length_u, length_w = surface.get_max_lengths()
        num_points_u = self.get_num_points(length_u, density_u)
        num_points_w = self.get_num_points(length_w, density_w)
        data = {
            "path": surface.get_path(),
            "flipped_normal": surface.is_normal_flipped,
            "num_points": (num_points_u, num_points_w),
            "distributions": (distribution_u, distribution_w),
        }
        self.surfaces.append(data)

    @staticmethod
    def get_num_points(length: float, density: int | float) -> int:
        """Returns number of points along a dimension.

        Args:
            length: Lagest length of relevant surface boundary curves.
            density: Panel density along the dimension.
                Integer values represent the number of panels,
                while float values represent panel size.

        Returns:
            num_points: Number of points needed along surface dimension.
        """
        num_points = density + 1
        if isinstance(density, float):
            num_points = int(np.ceil(length / density) + 1)
        return num_points

    @staticmethod
    def _generate_mesh_points(mesh) -> NDArray3xNxN[np.float64]:
        """Generates mesh points"""
        path = mesh["path"]
        num_points_u, num_points_w = mesh["num_points"]
        distribution_u, distribution_w = mesh["distributions"]
        ufn = distribution_u.get_dist_fn()
        wfn = distribution_w.get_dist_fn()
        mp = np.zeros((3, num_points_u, num_points_w))
        for i, u in enumerate(np.linspace(0, 1, num=num_points_u, endpoint=True)):
            for j, w in enumerate(np.linspace(0, 1, num=num_points_w, endpoint=True)):
                mp[:, i, j] = path(ufn(u), wfn(w))
        return mp

    @staticmethod
    def _generate_panels(
        mesh_points: NDArray3xNxN[np.float64], flipped_normal: bool
    ) -> list[list[float]]:
        """Returns list of quadrilateral panels.

        Each panel is defined as a list of 12 floating numbers,
        representing the xyz coordinates of the four panel vertices:
        panel = [x0, y0, z0, x1, y1, z1, x2, y2, z2, x3, y3, z3]
        """
        panels = []
        mp = mesh_points
        for j in range(0, mp.shape[2] - 1):
            for i in range(0, mp.shape[1] - 1):
                xyz1 = mp[:, i, j]
                xyz2 = mp[:, i + 1, j]
                xyz3 = mp[:, i + 1, j + 1]
                xyz4 = mp[:, i, j + 1]
                if flipped_normal:
                    xyz1, xyz2, xyz3, xyz4 = xyz4, xyz3, xyz2, xyz1
                panels.append(
                    [
                        xyz1[0],
                        xyz1[1],
                        xyz1[2],
                        xyz2[0],
                        xyz2[1],
                        xyz2[2],
                        xyz3[0],
                        xyz3[1],
                        xyz3[2],
                        xyz4[0],
                        xyz4[1],
                        xyz4[2],
                    ]
                )
        return panels

    def get_panels(self) -> list[list[float]]:
        """Generates and returns panels for each item in the surfaces attribute list.

        Returns:
            panels: List of quadrilateral panels.
                Each panel is defined as a list of 12 floating numbers,
                representing the xyz coordinates of the four panel vertices:
                panel = [x0, y0, z0, x1, y1, z1, x2, y2, z2, x3, y3, z3].
        """
        panels = []
        for data in self.surfaces:
            mesh_points = self._generate_mesh_points(data)
            surface_panels = self._generate_panels(mesh_points, data["flipped_normal"])
            panels += surface_panels
        return panels

surfaces class-attribute instance-attribute #

surfaces = []

List of surface dictionaries with mesh information.

Each surface dictionary follows the structure:

.. code-block:: python3 surface = { "path": Callable[[float], NDArray3], "flipped_normal": bool, "num_points": tuple[int], "distributions": tuple[MeshDistribution], }

Note

Above code block works in Visual Studio Code.

add_surface #

add_surface(surface, density_u=0.2, density_w=0.2, distribution_u=LinearDistribution(), distribution_w=LinearDistribution())

Adds a surface to the mesh.

Parameters:

Name Type Description Default
surface Surface

Surface object to be added.

 required
density_u int | float

Panel density along the u dimension. Integer values represent the number of panels, while float values represent panel size.

 0.2
density_w int | float

Panel density along the w dimension. Integer values represent the number of panels, while float values represent panel size.

 0.2
distribution_u MeshDistribution

Distribution type along the u dimension.

 LinearDistribution()
distribution_w MeshDistribution

Distribution type along the w dimension.

 LinearDistribution()

Examples:

Initialize a mesh and add a surface with two panels (linearly distributed by default) along the u dimension and a panel length of 0.1 units along the w dimension. These panels are distributed exponentially.

>>> surface = PlaneSurface(Point(0, 0, 0), Point(1, 0, 0), Point(0, 1, 0))
>>> dist_exp = ExponentialDistribution()
>>> mesh = MeshGenerator()
>>> mesh.add_surface(surface, density_u=2, density_w=0.1, distribution_w=dist_exp)

The user is referred to pymesh.mesh.mesh_distributions for more information on distribution_u and distribution_w options.

Note

Above example code block style works with MkDocs, but does not look nice in Visual Studio Code.

Source code in pymesh/mesh/mesh_generator.py 
def add_surface(
    self,
    surface: Surface,
    density_u: int | float = 0.2,
    density_w: int | float = 0.2,
    distribution_u: MeshDistribution = LinearDistribution(),
    distribution_w: MeshDistribution = LinearDistribution(),
) -> None:
    """Adds a surface to the mesh.

    Args:
        surface: Surface object to be added.
        density_u: Panel density along the u dimension.
            Integer values represent the number of panels,
            while float values represent panel size.
        density_w: Panel density along the w dimension.
            Integer values represent the number of panels,
            while float values represent panel size.
        distribution_u: Distribution type along the u dimension.
        distribution_w: Distribution type along the w dimension.

    Examples:
        Initialize a mesh and add a surface with two panels (linearly distributed
        by default) along the u dimension and a panel length of 0.1 units along
        the w dimension. These panels are distributed exponentially.

        >>> surface = PlaneSurface(Point(0, 0, 0), Point(1, 0, 0), Point(0, 1, 0))
        >>> dist_exp = ExponentialDistribution()
        >>> mesh = MeshGenerator()
        >>> mesh.add_surface(surface, density_u=2, density_w=0.1, distribution_w=dist_exp)

        The user is referred to [pymesh.mesh.mesh_distributions][] for more
        information on distribution_u and distribution_w options.

    Note:
        Above example code block style works with MkDocs, but does not look nice
        in Visual Studio Code.
    """
    length_u, length_w = surface.get_max_lengths()
    num_points_u = self.get_num_points(length_u, density_u)
    num_points_w = self.get_num_points(length_w, density_w)
    data = {
        "path": surface.get_path(),
        "flipped_normal": surface.is_normal_flipped,
        "num_points": (num_points_u, num_points_w),
        "distributions": (distribution_u, distribution_w),
    }
    self.surfaces.append(data)

get_num_points staticmethod #

get_num_points(length, density)

Returns number of points along a dimension.

Parameters:

Name Type Description Default
length float

Lagest length of relevant surface boundary curves.

 required
density int | float

Panel density along the dimension. Integer values represent the number of panels, while float values represent panel size.

 required

Returns:

Name Type Description
num_points int

Number of points needed along surface dimension.
Source code in pymesh/mesh/mesh_generator.py 
@staticmethod
def get_num_points(length: float, density: int | float) -> int:
    """Returns number of points along a dimension.

    Args:
        length: Lagest length of relevant surface boundary curves.
        density: Panel density along the dimension.
            Integer values represent the number of panels,
            while float values represent panel size.

    Returns:
        num_points: Number of points needed along surface dimension.
    """
    num_points = density + 1
    if isinstance(density, float):
        num_points = int(np.ceil(length / density) + 1)
    return num_points

get_panels #

get_panels()

Generates and returns panels for each item in the surfaces attribute list.

Returns:

Name Type Description
panels list[list[float]]

List of quadrilateral panels. Each panel is defined as a list of 12 floating numbers, representing the xyz coordinates of the four panel vertices: panel = [x0, y0, z0, x1, y1, z1, x2, y2, z2, x3, y3, z3].
Source code in pymesh/mesh/mesh_generator.py 
def get_panels(self) -> list[list[float]]:
    """Generates and returns panels for each item in the surfaces attribute list.

    Returns:
        panels: List of quadrilateral panels.
            Each panel is defined as a list of 12 floating numbers,
            representing the xyz coordinates of the four panel vertices:
            panel = [x0, y0, z0, x1, y1, z1, x2, y2, z2, x3, y3, z3].
    """
    panels = []
    for data in self.surfaces:
        mesh_points = self._generate_mesh_points(data)
        surface_panels = self._generate_panels(mesh_points, data["flipped_normal"])
        panels += surface_panels
    return panels