.. Comment: this file is automatically generated by `update_example_docs.py`.
   It should not be modified manually.

GUI callbacks
==========================================


Asynchronous usage of GUI elements: we can attach callbacks that are called as soon as
we get updates.



.. code-block:: python
        :linenos:


        import time

        import numpy as np
        from typing_extensions import assert_never

        import viser


        def main() -> None:
            server = viser.ViserServer()

            gui_reset_scene = server.gui.add_button("Reset Scene")

            gui_plane = server.gui.add_dropdown(
                "Grid plane", ("xz", "xy", "yx", "yz", "zx", "zy")
            )

            def update_plane() -> None:
                server.scene.add_grid(
                    "/grid",
                    width=10.0,
                    height=20.0,
                    width_segments=10,
                    height_segments=20,
                    plane=gui_plane.value,
                )

            gui_plane.on_update(lambda _: update_plane())

            with server.gui.add_folder("Control"):
                gui_show_frame = server.gui.add_checkbox("Show Frame", initial_value=True)
                gui_show_everything = server.gui.add_checkbox(
                    "Show Everything", initial_value=True
                )
                gui_axis = server.gui.add_dropdown("Axis", ("x", "y", "z"))
                gui_include_z = server.gui.add_checkbox("Z in dropdown", initial_value=True)

                @gui_include_z.on_update
                def _(_) -> None:
                    gui_axis.options = ("x", "y", "z") if gui_include_z.value else ("x", "y")

                with server.gui.add_folder("Sliders"):
                    gui_location = server.gui.add_slider(
                        "Location", min=-5.0, max=5.0, step=0.05, initial_value=0.0
                    )
                    gui_num_points = server.gui.add_slider(
                        "# Points", min=1000, max=200_000, step=1000, initial_value=10_000
                    )

            def draw_frame() -> None:
                axis = gui_axis.value
                if axis == "x":
                    pos = (gui_location.value, 0.0, 0.0)
                elif axis == "y":
                    pos = (0.0, gui_location.value, 0.0)
                elif axis == "z":
                    pos = (0.0, 0.0, gui_location.value)
                else:
                    assert_never(axis)

                server.scene.add_frame(
                    "/frame",
                    wxyz=(1.0, 0.0, 0.0, 0.0),
                    position=pos,
                    show_axes=gui_show_frame.value,
                    axes_length=5.0,
                )

            def draw_points() -> None:
                num_points = gui_num_points.value
                server.scene.add_point_cloud(
                    "/frame/point_cloud",
                    points=np.random.normal(size=(num_points, 3)),
                    colors=np.random.randint(0, 256, size=(num_points, 3)),
                )

            # We can (optionally) also attach callbacks!
            # Here, we update the point clouds + frames whenever any of the GUI items are updated.
            gui_show_frame.on_update(lambda _: draw_frame())
            gui_show_everything.on_update(
                lambda _: server.scene.set_global_visibility(gui_show_everything.value)
            )
            gui_axis.on_update(lambda _: draw_frame())
            gui_location.on_update(lambda _: draw_frame())
            gui_num_points.on_update(lambda _: draw_points())

            @gui_reset_scene.on_click
            def _(_) -> None:
                """Reset the scene when the reset button is clicked."""
                gui_show_frame.value = True
                gui_location.value = 0.0
                gui_axis.value = "x"
                gui_num_points.value = 10_000

                draw_frame()
                draw_points()

            # Finally, let's add the initial frame + point cloud and just loop infinitely. :)
            update_plane()
            draw_frame()
            draw_points()
            while True:
                time.sleep(1.0)


        if __name__ == "__main__":
            main()