{
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    {
      "cell_type": "code",
      "execution_count": null,
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      "source": [
        "%matplotlib inline"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Light Actors {#light_actors_example}\n\nPositional lights in PyVista have customizable beam shapes, see the\n`light_beam_shape_example`{.interpreted-text role=\"ref\"} example.\nSpotlights are special in the sense that they are unidirectional lights\nwith a finite position, so they can be visualized using a cone.\n\nThis is exactly the purpose of a `vtk.vtkLightActor`, the functionality\nof which can be enabled for spotlights:\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import numpy as np\n\nimport pyvista as pv\nfrom pyvista import examples\n\ncow = examples.download_cow()\ncow.rotate_x(90, inplace=True)\nplotter = pv.Plotter(lighting='none', window_size=(1000, 1000))\nplotter.add_mesh(cow, color='white')\nfloor = pv.Plane(center=(*cow.center[:2], cow.bounds[-2]), i_size=30, j_size=25)\nplotter.add_mesh(floor, color='green')\n\nUFO = pv.Light(position=(0, 0, 10), focal_point=(0, 0, 0), color='white')\nUFO.positional = True\nUFO.cone_angle = 40\nUFO.exponent = 10\nUFO.intensity = 3\nUFO.show_actor()\nplotter.add_light(UFO)\n\n# enable shadows to better demonstrate lighting\nplotter.enable_shadows()\n\nplotter.camera_position = [(28, 30, 22), (0.77, 0, -0.44), (0, 0, 1)]\nplotter.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Light actors can be very useful when designing complex scenes where\nspotlights are involved in lighting.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "plotter = pv.Plotter(lighting='none')\nplane = pv.Plane(i_size=4, j_size=4)\nplotter.add_mesh(plane, color='white')\n\nrot120 = np.array([[-0.5, -np.sqrt(3) / 2, 0], [np.sqrt(3) / 2, -0.5, 0], [0, 0, 1]])\n\nposition = (-1.5, -1.5, 3)\nfocus = (-0.5, -0.5, 0)\ncolors = ['red', 'lime', 'blue']\nfor color in colors:\n    position = rot120 @ position\n    focus = rot120 @ focus\n    light = pv.Light(position=position, focal_point=focus, color=color)\n    light.positional = True\n    light.cone_angle = 15\n    light.show_actor()\n    plotter.add_light(light)\n\nplotter.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "One thing to watch out for is that the light actors are represented such\nthat their cone has a fixed height. This implies that for very large\ncone angles we typically end up with enormous light actors, in which\ncase setting a manual camera position before rendering is usually a good\nidea. Increasing the first example\\'s cone angle and omitting the manual\ncamera positioning exemplifies the problem:\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "plotter = pv.Plotter(lighting='none')\nplotter.add_mesh(cow, color='white')\nfloor = pv.Plane(center=(*cow.center[:2], cow.bounds[-2]), i_size=30, j_size=25)\nplotter.add_mesh(floor, color='green')\n\nUFO = pv.Light(position=(0, 0, 10), focal_point=(0, 0, 0), color='white')\nUFO.positional = True\nUFO.cone_angle = 89\nUFO.exponent = 10\nUFO.intensity = 3\nUFO.show_actor()\nplotter.add_light(UFO)\n\nplotter.show()"
      ]
    }
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