{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Using VTK Algorithms\n\nIn this exercise, you will use a VTK Algorithm directly to filter a\nPyVista mesh.\n\nVTK algorithms (filters) follow a standard flow for most cases:\n\n1.  Instantiate the algorithm\n2.  Set the input data object or connection: `.SetInputDataObject(mesh)`\n3.  Adjust algorithm parameters with the setter methods, e.g.,\n    `SetParameterName(value)`\n4.  Call `.Update()` to run the algorithm\n5.  Retrieve the output of the algorithm: `output = alg.GetOutput()`\n\nLet\\'s see if we can try a few VTK algorithms with that standard\nworkflow.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import pyvista as pv\nimport vtk\nfrom pyvista import examples"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Here is a sample mesh\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "mesh = examples.load_random_hills()\nmesh"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "mesh.plot()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Simple Filter\n\nLet\\'s start out with a simple VTK filter: `vtkOutlineFilter`\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "help(vtk.vtkOutlineFilter)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Try using this VTK filter yourself here:\n\nRemember that you will have to wrap the output of the algorithm with\n`pyvista.wrap`{.interpreted-text role=\"func\"}\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "alg = vtk.vtkOutlineFilter()\n\n# (your code here, answer below)\n\noutline = pv.wrap(alg.GetOutput())\noutline"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "alg.SetInputDataObject(mesh)\nalg.SetGenerateFaces(False)  # noqa: FBT003\nalg.Update()\n\noutline = pv.wrap(alg.GetOutput())\noutline"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "::: note\n::: title\nNote\n:::\n\nNote that the about filter can be replaced with a `.outline()` filter in\nPyVista\n:::\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "pl = pv.Plotter()\npl.add_mesh(mesh)\npl.add_mesh(outline, color=\"k\")\npl.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Find your own filter\n\nTake a look at VTK\\'s examples and documentation to find a filter you\\'d\nlike to apply to your mesh. The instructors will be around to help you\nimplement.\n\nSee <https://kitware.github.io/vtk-examples/site/Python/>\n"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "```{=html}\n<center>\n  <a target=\"_blank\" href=\"https://colab.research.google.com/github/pyvista/pyvista-tutorial/blob/gh-pages/notebooks/tutorial/06_vtk/c_vtk_algorithms.ipynb\">\n    <img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/ width=\"150px\">\n  </a>\n</center>\n```\n"
      ]
    }
  ],
  "metadata": {
    "kernelspec": {
      "display_name": "Python 3",
      "language": "python",
      "name": "python3"
    },
    "language_info": {
      "codemirror_mode": {
        "name": "ipython",
        "version": 3
      },
      "file_extension": ".py",
      "mimetype": "text/x-python",
      "name": "python",
      "nbconvert_exporter": "python",
      "pygments_lexer": "ipython3",
      "version": "3.12.12"
    }
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  "nbformat": 4,
  "nbformat_minor": 0
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