{
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    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
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      "source": [
        "%gui qt"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Display Mesh Normals\n\nShow how to display mesh normals on a mesh.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "from vispy import app, scene\nfrom vispy.io import read_mesh, load_data_file\nfrom vispy.scene.visuals import Mesh, MeshNormals\nfrom vispy.visuals.filters import WireframeFilter\n\n\nmesh_file = load_data_file('orig/triceratops.obj.gz')\nvertices, faces, _, _ = read_mesh(mesh_file)\n\nmesh = Mesh(vertices, faces, shading='flat')\nmeshdata = mesh.mesh_data\n\nwireframe_filter = WireframeFilter(color='lightblue')\nmesh.attach(wireframe_filter)\n\nface_normals = MeshNormals(meshdata, primitive='face', color='yellow')\nvertex_normals = MeshNormals(meshdata, primitive='vertex', color='orange',\n                             width=2)\n\ncanvas = scene.SceneCanvas(keys='interactive', bgcolor='white')\nview = canvas.central_widget.add_view()\nview.camera = 'arcball'\nview.add(mesh)\nface_normals.parent = mesh\nvertex_normals.parent = mesh\n\n\n@canvas.events.key_press.connect\ndef on_key_press(event):\n    if event.key == 'f':\n        face_normals.visible = not face_normals.visible\n        canvas.update()\n    elif event.key == 'v':\n        vertex_normals.visible = not vertex_normals.visible\n        canvas.update()\n\n\ncanvas.show()\n\n\nif __name__ == \"__main__\":\n    print('Key bindings:')\n    print(' f : toggle face normals')\n    print(' v : toggle vertex normals')\n    app.run()"
      ]
    }
  ],
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      "display_name": "Python 3",
      "language": "python",
      "name": "python3"
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