.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "examples/sphere.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_examples_sphere.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_examples_sphere.py:


Using external modules to create a mesh
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Tetrahedralize a sphere

.. GENERATED FROM PYTHON SOURCE LINES 7-12

.. code-block:: Python


    # sphinx_gallery_thumbnail_number = 2
    import pyvista as pv
    import tetgen








.. GENERATED FROM PYTHON SOURCE LINES 13-16

Using PyVista
~~~~~~~~~~~~~
Create a surface mesh using ``pyvista`` and then tetrahedralize it.

.. GENERATED FROM PYTHON SOURCE LINES 16-23

.. code-block:: Python

    sphere = pv.Sphere()
    tet = tetgen.TetGen(sphere)
    tet.tetrahedralize(order=1, mindihedral=20, minratio=1.5)
    grid = tet.grid
    grid.plot(show_edges=True)





.. image-sg:: /examples/images/sphx_glr_sphere_001.png
   :alt: sphere
   :srcset: /examples/images/sphx_glr_sphere_001.png
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 24-25

Use pyvista to plot

.. GENERATED FROM PYTHON SOURCE LINES 25-41

.. code-block:: Python


    # get cell centroids
    cell_center = grid.cell_centers().points

    # extract cells below the 0 xy plane
    mask = cell_center[:, 2] < 0
    cell_ind = mask.nonzero()[0]
    subgrid = grid.extract_cells(cell_ind)

    # advanced plotting
    plotter = pv.Plotter()
    plotter.add_mesh(subgrid, "lightgrey", lighting=True, show_edges=True)
    plotter.add_mesh(sphere, "r", "wireframe")
    plotter.add_legend([[" Input Mesh ", "r"], [" Tessellated Mesh ", "black"]])
    plotter.show()




.. image-sg:: /examples/images/sphx_glr_sphere_002.png
   :alt: sphere
   :srcset: /examples/images/sphx_glr_sphere_002.png
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 42-44

Use pyvista to compute cell quality.  This is the minimum scaled
jacobian of each cell.

.. GENERATED FROM PYTHON SOURCE LINES 44-59

.. code-block:: Python


    cell_qual = subgrid.compute_cell_quality()["CellQuality"]
    print(f"Mean cell quality: {cell_qual.mean():.3}")

    # plot quality
    subgrid.plot(
        scalars=cell_qual,
        scalar_bar_args={"title": "Quality"},
        cmap="bwr",
        clim=[0, 1],
        flip_scalars=True,
        show_edges=True,
    )





.. image-sg:: /examples/images/sphx_glr_sphere_003.png
   :alt: sphere
   :srcset: /examples/images/sphx_glr_sphere_003.png
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    Mean cell quality: 0.616




.. GENERATED FROM PYTHON SOURCE LINES 60-69

Using pyacvd
~~~~~~~~~~~~

We can use `pyacvd <https://github.com/pyvista/pyacvd>`_ to create a
more uniform mesh using the mesh generated from ``pyvista``.  We can
use the ``pyacvd`` module to generate a more uniform surface mesh
and then tetrahedralize that.

Here we re-run the above example, except using a more uniform surface

.. GENERATED FROM PYTHON SOURCE LINES 69-85

.. code-block:: Python


    import pyacvd

    n_surf = 1000

    clustered = pyacvd.Clustering(sphere)
    clustered.subdivide(2)
    clustered.cluster(n_surf)
    uniform_surf = clustered.create_mesh()

    # generate interior mesh and plot the surface of it
    tet = tetgen.TetGen(uniform_surf)
    tet.tetrahedralize(order=1, mindihedral=20, minratio=1.5)
    uniform_grid = tet.grid
    uniform_grid.plot(show_edges=True)




.. image-sg:: /examples/images/sphx_glr_sphere_004.png
   :alt: sphere
   :srcset: /examples/images/sphx_glr_sphere_004.png
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 86-87

Plot the cross section of the tetrahedralization

.. GENERATED FROM PYTHON SOURCE LINES 87-107

.. code-block:: Python


    cell_center = uniform_grid.cell_centers().points

    # extract cells below the 0 xy plane
    mask = cell_center[:, 2] < 0
    cell_ind = mask.nonzero()[0]
    subgrid = uniform_grid.extract_cells(cell_ind)

    cell_qual = subgrid.compute_cell_quality()["CellQuality"]
    print(f"Mean cell quality: {cell_qual.mean():.3}")

    # plot quality
    subgrid.plot(
        scalars=cell_qual,
        scalar_bar_args={"title": "Quality"},
        cmap="bwr",
        clim=[0, 1],
        flip_scalars=True,
        show_edges=True,
    )



.. image-sg:: /examples/images/sphx_glr_sphere_005.png
   :alt: sphere
   :srcset: /examples/images/sphx_glr_sphere_005.png
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    Mean cell quality: 0.642





.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 3.782 seconds)


.. _sphx_glr_download_examples_sphere.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: sphere.ipynb <sphere.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: sphere.py <sphere.py>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_