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

.. only:: html

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

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

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

.. _sphx_glr_gallery_scene_marker_picking.py:


Picking Markers
===============

Demonstrates how to identify (pick) markers. Hover markers to change their
symbol and color.

Controls:
* p  - Toggle picking view - shows the colors encoding marker ID
* r  - Reset marker symbols and colors

.. GENERATED FROM PYTHON SOURCE LINES 18-156



.. image-sg:: /gallery/scene/images/sphx_glr_marker_picking_001.png
   :alt: marker picking
   :srcset: /gallery/scene/images/sphx_glr_marker_picking_001.png
   :class: sphx-glr-single-img





.. code-block:: Python

    import random
    import time
    import numpy as np
    from scipy.constants import golden as GOLDEN

    from vispy import app, scene
    from vispy.scene.visuals import Markers
    from vispy.visuals.filters import MarkerPickingFilter

    canvas = scene.SceneCanvas(keys='interactive', bgcolor='black')
    view = canvas.central_widget.add_view(camera="panzoom")
    view.camera.rect = (-1, -1, 2, 2)

    # floret pattern
    n = 10_000
    radius = np.linspace(0, 0.9, n)**0.6  # prevent extreme density at center
    theta = np.arange(n) * GOLDEN
    pos = np.column_stack([radius * np.cos(theta), radius * np.sin(theta)])

    COLORS = [
        (1, 0, 0, 1),  # red
        (1, 0.5, 0, 1),  # orange
        (1, 1, 0, 1),  # yellow
        (0, 1, 0, 1),  # green
        (0, 0, 1, 1),  # blue
        (0.29, 0, 0.51, 1),  # indigo
        (0.93, 0.51, 0.93, 1),  # violet
    ]

    colors = np.zeros((n, 4), dtype=np.float32)
    colors[:, 0] = 1  # red
    colors[:, -1] = 1  # alpha
    _colors = colors.copy()

    symbols = list(Markers._symbol_shader_values.keys())
    symbols_ring = dict(zip(symbols, symbols[1:]))
    symbols_ring[symbols[-1]] = symbols[0]

    EDGE_COLOR = "white"
    MARKER_SIZE = 0.0125
    EDGE_WDITH = MARKER_SIZE / 10

    markers = Markers(
        pos=pos,
        edge_color=EDGE_COLOR,
        face_color=colors,
        size=MARKER_SIZE,
        edge_width=EDGE_WDITH,
        scaling="scene",
    )
    markers.update_gl_state(depth_test=True)
    view.add(markers)

    # Use filters to affect the rendering of the mesh.
    picking_filter = MarkerPickingFilter()
    markers.attach(picking_filter)


    @view.events.connect
    def on_viewbox_change(event):
        # workaround for vispy/#2501
        markers.update_gl_state(blend=not picking_filter.enabled)


    throttle = time.monotonic()


    @canvas.events.mouse_move.connect
    def on_mouse_move(event):
        global throttle
        # throttle mouse events to 50ms
        if time.monotonic() - throttle < 0.05:
            return
        throttle = time.monotonic()

        # adjust the event position for hidpi screens
        render_size = tuple(d * canvas.pixel_scale for d in canvas.size)
        x_pos = event.pos[0] * canvas.pixel_scale
        y_pos = render_size[1] - (event.pos[1] * canvas.pixel_scale)

        # render a small patch around the mouse cursor
        restore_state = not picking_filter.enabled
        picking_filter.enabled = True
        markers.update_gl_state(blend=False)
        picking_render = canvas.render(
            crop=(x_pos - 2, y_pos - 2, 5, 5),
            bgcolor=(0, 0, 0, 0),
            alpha=True,
        )
        if restore_state:
            picking_filter.enabled = False
        markers.update_gl_state(blend=not picking_filter.enabled)

        # unpack the face index from the color in the center pixel
        marker_idx = (picking_render.view(np.uint32) - 1)[2, 2, 0]

        if marker_idx >= 0 and marker_idx < len(pos):
            new_symbols = list(markers.symbol)
            new_symbol = symbols_ring[new_symbols[marker_idx]]
            new_symbols[marker_idx] = new_symbol

            colors[marker_idx] = random.choice(COLORS)
            markers.set_data(
                pos=pos,
                edge_color=EDGE_COLOR,
                face_color=colors,
                size=MARKER_SIZE,
                edge_width=EDGE_WDITH,
                symbol=new_symbols,
            )


    @canvas.events.key_press.connect
    def on_key_press(event):
        global colors
        if event.key == 'p':
            # toggle face picking view
            picking_filter.enabled = not picking_filter.enabled
            markers.update_gl_state(blend=not picking_filter.enabled)
            markers.update()
        if event.key == 'r':
            # reset marker symbols
            colors = _colors.copy()
            markers.set_data(
                pos=pos,
                edge_color=EDGE_COLOR,
                face_color=colors,
                size=MARKER_SIZE,
                edge_width=EDGE_WDITH,
            )


    canvas.show()


    if __name__ == "__main__":
        print(__doc__)
        app.run()


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

   **Total running time of the script:** (0 minutes 1.927 seconds)


.. _sphx_glr_download_gallery_scene_marker_picking.py:

.. only:: html

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

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

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

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

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


.. only:: html

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

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