3b1b-manim/manimlib/scene/scene.py

from __future__ import annotations

from collections import OrderedDict
from functools import wraps
import inspect
import os
import platform
import pyperclip
import random
import time

import numpy as np
from tqdm import tqdm as ProgressDisplay

from manimlib.animation.animation import prepare_animation
from manimlib.camera.camera import Camera
from manimlib.constants import ARROW_SYMBOLS
from manimlib.constants import DEFAULT_WAIT_TIME
from manimlib.constants import COMMAND_MODIFIER
from manimlib.constants import SHIFT_MODIFIER
from manimlib.event_handler import EVENT_DISPATCHER
from manimlib.event_handler.event_type import EventType
from manimlib.logger import log
from manimlib.mobject.mobject import _AnimationBuilder
from manimlib.mobject.mobject import Group
from manimlib.mobject.mobject import Mobject
from manimlib.mobject.mobject import Point
from manimlib.mobject.types.vectorized_mobject import VGroup
from manimlib.mobject.types.vectorized_mobject import VMobject
from manimlib.scene.scene_file_writer import SceneFileWriter
from manimlib.utils.config_ops import digest_config
from manimlib.utils.family_ops import extract_mobject_family_members
from manimlib.utils.iterables import list_difference_update

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from typing import Callable, Iterable

    from PIL.Image import Image

    from manimlib.animation.animation import Animation


PAN_3D_KEY = 'd'
FRAME_SHIFT_KEY = 'f'
ZOOM_KEY = 'z'
RESET_FRAME_KEY = 'r'
QUIT_KEY = 'q'


class Scene(object):
    CONFIG = {
        "window_config": {},
        "camera_class": Camera,
        "camera_config": {},
        "file_writer_config": {},
        "skip_animations": False,
        "always_update_mobjects": False,
        "random_seed": 0,
        "start_at_animation_number": None,
        "end_at_animation_number": None,
        "leave_progress_bars": False,
        "preview": True,
        "presenter_mode": False,
        "show_animation_progress": False,
        "pan_sensitivity": 3,
        "max_num_saved_states": 50,
    }

    def __init__(self, **kwargs):
        digest_config(self, kwargs)
        if self.preview:
            from manimlib.window import Window
            self.window = Window(scene=self, **self.window_config)
            self.camera_config["ctx"] = self.window.ctx
            self.camera_config["fps"] = 30  # Where's that 30 from?
            self.undo_stack = []
            self.redo_stack = []
        else:
            self.window = None

        self.camera: Camera = self.camera_class(**self.camera_config)
        self.file_writer = SceneFileWriter(self, **self.file_writer_config)
        self.mobjects: list[Mobject] = [self.camera.frame]
        self.id_to_mobject_map: dict[int, Mobject] = dict()
        self.num_plays: int = 0
        self.time: float = 0
        self.skip_time: float = 0
        self.original_skipping_status: bool = self.skip_animations
        self.checkpoint_states: dict[str, list[tuple[Mobject, Mobject]]] = dict()

        if self.start_at_animation_number is not None:
            self.skip_animations = True
        if self.file_writer.has_progress_display:
            self.show_animation_progress = False

        # Items associated with interaction
        self.mouse_point = Point()
        self.mouse_drag_point = Point()
        self.hold_on_wait = self.presenter_mode
        self.inside_embed = False
        self.quit_interaction = False

        # Much nicer to work with deterministic scenes
        if self.random_seed is not None:
            random.seed(self.random_seed)
            np.random.seed(self.random_seed)

    def __str__(self) -> str:
        return self.__class__.__name__

    def run(self) -> None:
        self.virtual_animation_start_time: float = 0
        self.real_animation_start_time: float = time.time()
        self.file_writer.begin()

        self.setup()
        try:
            self.construct()
            self.interact()
        except EndScene:
            pass
        except KeyboardInterrupt:
            # Get rid keyboard interupt symbols
            print("", end="\r")
            self.file_writer.ended_with_interrupt = True
        self.tear_down()

    def setup(self) -> None:
        """
        This is meant to be implement by any scenes which
        are comonly subclassed, and have some common setup
        involved before the construct method is called.
        """
        pass

    def construct(self) -> None:
        # Where all the animation happens
        # To be implemented in subclasses
        pass

    def tear_down(self) -> None:
        self.stop_skipping()
        self.file_writer.finish()
        if self.window:
            self.window.destroy()
            self.window = None

    def interact(self) -> None:
        # If there is a window, enter a loop
        # which updates the frame while under
        # the hood calling the pyglet event loop
        if self.window is None:
            return
        log.info(
            "Tips: You are now in the interactive mode. Now you can use the keyboard"
            " and the mouse to interact with the scene. Just press `command + q` or `esc`"
            " if you want to quit."
        )
        self.skip_animations = False
        self.refresh_static_mobjects()
        while not self.is_window_closing():
            self.update_frame(1 / self.camera.fps)

    def embed(self, close_scene_on_exit: bool = True) -> None:
        if not self.preview:
            return  # Embed is only relevant with a preview
        self.inside_embed = True
        self.stop_skipping()
        self.update_frame()
        self.save_state()

        # Configure and launch embedded IPython terminal
        from IPython.terminal import embed, pt_inputhooks
        shell = embed.InteractiveShellEmbed.instance()

        # Use the locals namespace of the caller
        local_ns = inspect.currentframe().f_back.f_locals
        # Add a few custom shortcuts
        local_ns.update({
            name: getattr(self, name)
            for name in [
                "play", "wait", "add", "remove", "clear",
                "save_state", "undo", "redo", "i2g", "i2m"
            ]
        })

        # This is useful if one wants to re-run a block of scene
        # code, while developing, tweaking it each time.
        # As long as the copied selection starts with a comment,
        # this will revert to the state of the scene at the first
        # point of running.
        def checkpoint_paste(skip=False, show_progress=True):
            pasted = pyperclip.paste()
            line0 = pasted.lstrip().split("\n")[0]
            if line0.startswith("#"):
                if line0 not in self.checkpoint_states:
                    self.checkpoint(line0)
                else:
                    self.revert_to_checkpoint(line0)
                    self.update_frame(dt=0)
            if skip:
                originally_skip = self.skip_animations
                self.skip_animations = True
            if show_progress:
                originally_show_animation_progress = self.show_animation_progress
                self.show_animation_progress = True
            shell.run_line_magic("paste", "")
            if skip:
                self.skip_animations = originally_skip
            if show_progress:
                self.show_animation_progress = originally_show_animation_progress

        local_ns['checkpoint_paste'] = checkpoint_paste

        # Enables gui interactions during the embed
        def inputhook(context):
            while not context.input_is_ready():
                if not self.is_window_closing():
                    self.update_frame(dt=0)
            if self.is_window_closing():
                shell.ask_exit()

        pt_inputhooks.register("manim", inputhook)
        shell.enable_gui("manim")

        # This is hacky, but there's an issue with ipython which is that
        # when you define lambda's or list comprehensions during a shell session,
        # they are not aware of local variables in the surrounding scope. Because
        # That comes up a fair bit during scene construction, to get around this,
        # we (admittedly sketchily) update the global namespace to match the local
        # namespace, since this is just a shell session anyway.
        shell.events.register(
            "pre_run_cell",
            lambda: shell.user_global_ns.update(shell.user_ns)
        )

        # Operation to run after each ipython command
        def post_cell_func():
            self.refresh_static_mobjects()
            if not self.is_window_closing():
                self.update_frame(dt=0, ignore_skipping=True)
            self.save_state()

        shell.events.register("post_run_cell", post_cell_func)

        shell(local_ns=local_ns, stack_depth=2)

        # End scene when exiting an embed
        if close_scene_on_exit:
            raise EndScene()

    # Only these methods should touch the camera

    def get_image(self) -> Image:
        return self.camera.get_image()

    def show(self) -> None:
        self.update_frame(ignore_skipping=True)
        self.get_image().show()

    def update_frame(self, dt: float = 0, ignore_skipping: bool = False) -> None:
        self.increment_time(dt)
        self.update_mobjects(dt)
        if self.skip_animations and not ignore_skipping:
            return

        if self.is_window_closing():
            raise EndScene()

        if self.window:
            self.window.clear()
        self.camera.clear()
        self.camera.capture(*self.mobjects)

        if self.window:
            self.window.swap_buffers()
            vt = self.time - self.virtual_animation_start_time
            rt = time.time() - self.real_animation_start_time
            if rt < vt:
                self.update_frame(0)

    def emit_frame(self) -> None:
        if not self.skip_animations:
            self.file_writer.write_frame(self.camera)

    # Related to updating

    def update_mobjects(self, dt: float) -> None:
        for mobject in self.mobjects:
            mobject.update(dt)

    def should_update_mobjects(self) -> bool:
        return self.always_update_mobjects or any([
            len(mob.get_family_updaters()) > 0
            for mob in self.mobjects
        ])

    def has_time_based_updaters(self) -> bool:
        return any([
            sm.has_time_based_updater()
            for mob in self.mobjects()
            for sm in mob.get_family()
        ])

    # Related to time

    def get_time(self) -> float:
        return self.time

    def increment_time(self, dt: float) -> None:
        self.time += dt

    # Related to internal mobject organization

    def get_top_level_mobjects(self) -> list[Mobject]:
        # Return only those which are not in the family
        # of another mobject from the scene
        mobjects = self.get_mobjects()
        families = [m.get_family() for m in mobjects]

        def is_top_level(mobject):
            num_families = sum([
                (mobject in family)
                for family in families
            ])
            return num_families == 1
        return list(filter(is_top_level, mobjects))

    def get_mobject_family_members(self) -> list[Mobject]:
        return extract_mobject_family_members(self.mobjects)

    def add(self, *new_mobjects: Mobject):
        """
        Mobjects will be displayed, from background to
        foreground in the order with which they are added.
        """
        self.remove(*new_mobjects)
        self.mobjects += new_mobjects
        self.id_to_mobject_map.update({
            id(sm): sm
            for m in new_mobjects
            for sm in m.get_family()
        })
        return self

    def add_mobjects_among(self, values: Iterable):
        """
        This is meant mostly for quick prototyping,
        e.g. to add all mobjects defined up to a point,
        call self.add_mobjects_among(locals().values())
        """
        self.add(*filter(
            lambda m: isinstance(m, Mobject),
            values
        ))
        return self

    def replace(self, mobject: Mobject, *replacements: Mobject):
        if mobject in self.mobjects:
            index = self.mobjects.index(mobject)
            self.mobjects = [
                *self.mobjects[:index],
                *replacements,
                *self.mobjects[index + 1:]
            ]
        return self

    def remove(self, *mobjects: Mobject):
        """
        Removes anything in mobjects from scenes mobject list, but in the event that one
        of the items to be removed is a member of the family of an item in mobject_list,
        the other family members are added back into the list.

        For example, if the scene includes Group(m1, m2, m3), and we call scene.remove(m1),
        the desired behavior is for the scene to then include m2 and m3 (ungrouped).
        """
        for mob in mobjects:
            # First restructure self.mobjects so that parents/grandparents/etc. are replaced
            # with their children, likewise for all ancestors in the extended family.
            for ancestor in mob.get_ancestors(extended=True):
                self.replace(ancestor, *ancestor.submobjects)
            self.mobjects = list_difference_update(self.mobjects, mob.get_family())
        return self

    def bring_to_front(self, *mobjects: Mobject):
        self.add(*mobjects)
        return self

    def bring_to_back(self, *mobjects: Mobject):
        self.remove(*mobjects)
        self.mobjects = list(mobjects) + self.mobjects
        return self

    def clear(self):
        self.mobjects = []
        return self

    def get_mobjects(self) -> list[Mobject]:
        return list(self.mobjects)

    def get_mobject_copies(self) -> list[Mobject]:
        return [m.copy() for m in self.mobjects]

    def point_to_mobject(
        self,
        point: np.ndarray,
        search_set: Iterable[Mobject] | None = None,
        buff: float = 0
    ) -> Mobject | None:
        """
        E.g. if clicking on the scene, this returns the top layer mobject
        under a given point
        """
        if search_set is None:
            search_set = self.mobjects
        for mobject in reversed(search_set):
            if mobject.is_point_touching(point, buff=buff):
                return mobject
        return None

    def get_group(self, *mobjects):
        if all(isinstance(m, VMobject) for m in mobjects):
            return VGroup(*mobjects)
        else:
            return Group(*mobjects)

    def id_to_mobject(self, id_value):
        return self.id_to_mobject_map[id_value]

    def ids_to_group(self, *id_values):
        return self.get_group(*filter(
            lambda x: x is not None,
            map(self.id_to_mobject, id_values)
        ))

    def i2g(self, *id_values):
        return self.ids_to_group(*id_values)

    def i2m(self, id_value):
        return self.id_to_mobject(id_value)

    # Related to skipping

    def update_skipping_status(self) -> None:
        if self.start_at_animation_number is not None:
            if self.num_plays == self.start_at_animation_number:
                self.skip_time = self.time
                if not self.original_skipping_status:
                    self.stop_skipping()
        if self.end_at_animation_number is not None:
            if self.num_plays >= self.end_at_animation_number:
                raise EndScene()

    def stop_skipping(self) -> None:
        self.virtual_animation_start_time = self.time
        self.skip_animations = False

    # Methods associated with running animations

    def get_time_progression(
        self,
        run_time: float,
        n_iterations: int | None = None,
        desc: str = "",
        override_skip_animations: bool = False
    ) -> list[float] | np.ndarray | ProgressDisplay:
        if self.skip_animations and not override_skip_animations:
            return [run_time]

        times = np.arange(0, run_time, 1 / self.camera.fps)

        if self.file_writer.has_progress_display:
            self.file_writer.set_progress_display_subdescription(desc)

        if self.show_animation_progress:
            return ProgressDisplay(
                times,
                total=n_iterations,
                leave=self.leave_progress_bars,
                ascii=True if platform.system() == 'Windows' else None,
                desc=desc,
            )
        else:
            return times

    def get_run_time(self, animations: Iterable[Animation]) -> float:
        return np.max([animation.get_run_time() for animation in animations])

    def get_animation_time_progression(
        self,
        animations: Iterable[Animation]
    ) -> list[float] | np.ndarray | ProgressDisplay:
        run_time = self.get_run_time(animations)
        description = f"{self.num_plays} {animations[0]}"
        if len(animations) > 1:
            description += ", etc."
        time_progression = self.get_time_progression(run_time, desc=description)
        return time_progression

    def get_wait_time_progression(
        self,
        duration: float,
        stop_condition: Callable[[], bool] | None = None
    ) -> list[float] | np.ndarray | ProgressDisplay:
        kw = {"desc": f"{self.num_plays} Waiting"}
        if stop_condition is not None:
            kw["n_iterations"] = -1  # So it doesn't show % progress
            kw["override_skip_animations"] = True
        return self.get_time_progression(duration, **kw)

    def prepare_animations(
        self,
        proto_animations: list[Animation | _AnimationBuilder],
        animation_config: dict,
    ):
        animations = list(map(prepare_animation, proto_animations))
        for anim in animations:
            # This is where kwargs to play like run_time and rate_func
            # get applied to all animations
            anim.update_config(**animation_config)
        return animations

    def handle_play_like_call(func):
        @wraps(func)
        def wrapper(self, *args, **kwargs):
            if self.inside_embed:
                self.save_state()
            if self.presenter_mode and self.num_plays == 0:
                self.hold_loop()

            self.update_skipping_status()
            should_write = not self.skip_animations
            if should_write:
                self.file_writer.begin_animation()

            if self.window:
                self.real_animation_start_time = time.time()
                self.virtual_animation_start_time = self.time

            self.refresh_static_mobjects()
            func(self, *args, **kwargs)

            if should_write:
                self.file_writer.end_animation()

            if self.inside_embed:
                self.save_state()

            if self.skip_animations and self.window is not None:
                # Show some quick frames along the way
                self.update_frame(dt=0, ignore_skipping=True)

            self.num_plays += 1
        return wrapper

    def refresh_static_mobjects(self) -> None:
        self.camera.refresh_static_mobjects()

    def begin_animations(self, animations: Iterable[Animation]) -> None:
        for animation in animations:
            animation.begin()
            # Anything animated that's not already in the
            # scene gets added to the scene.  Note, for
            # animated mobjects that are in the family of
            # those on screen, this can result in a restructuring
            # of the scene.mobjects list, which is usually desired.
            if animation.mobject not in self.mobjects:
                self.add(animation.mobject)

    def progress_through_animations(self, animations: Iterable[Animation]) -> None:
        last_t = 0
        for t in self.get_animation_time_progression(animations):
            dt = t - last_t
            last_t = t
            for animation in animations:
                animation.update_mobjects(dt)
                alpha = t / animation.run_time
                animation.interpolate(alpha)
            self.update_frame(dt)
            self.emit_frame()

    def finish_animations(self, animations: Iterable[Animation]) -> None:
        for animation in animations:
            animation.finish()
            animation.clean_up_from_scene(self)
        if self.skip_animations:
            self.update_mobjects(self.get_run_time(animations))
        else:
            self.update_mobjects(0)

    @handle_play_like_call
    def play(self, *proto_animations, **animation_config) -> None:
        if len(proto_animations) == 0:
            log.warning("Called Scene.play with no animations")
            return
        animations = self.prepare_animations(proto_animations, animation_config)
        self.begin_animations(animations)
        self.progress_through_animations(animations)
        self.finish_animations(animations)

    @handle_play_like_call
    def wait(
        self,
        duration: float = DEFAULT_WAIT_TIME,
        stop_condition: Callable[[], bool] = None,
        note: str = None,
        ignore_presenter_mode: bool = False
    ):
        self.update_mobjects(dt=0)  # Any problems with this?
        if self.presenter_mode and not self.skip_animations and not ignore_presenter_mode:
            if note:
                log.info(note)
            self.hold_loop()
        else:
            time_progression = self.get_wait_time_progression(duration, stop_condition)
            last_t = 0
            for t in time_progression:
                dt = t - last_t
                last_t = t
                self.update_frame(dt)
                self.emit_frame()
                if stop_condition is not None and stop_condition():
                    break
        self.refresh_static_mobjects()
        return self

    def hold_loop(self):
        while self.hold_on_wait:
            self.update_frame(dt=1 / self.camera.fps)
        self.hold_on_wait = True

    def wait_until(
        self,
        stop_condition: Callable[[], bool],
        max_time: float = 60
    ):
        self.wait(max_time, stop_condition=stop_condition)

    def force_skipping(self):
        self.original_skipping_status = self.skip_animations
        self.skip_animations = True
        return self

    def revert_to_original_skipping_status(self):
        if hasattr(self, "original_skipping_status"):
            self.skip_animations = self.original_skipping_status
        return self

    def add_sound(
        self,
        sound_file: str,
        time_offset: float = 0,
        gain: float | None = None,
        gain_to_background: float | None = None
    ):
        if self.skip_animations:
            return
        time = self.get_time() + time_offset
        self.file_writer.add_sound(sound_file, time, gain, gain_to_background)

    # Helpers for interactive development

    def get_state(self) -> SceneState:
        return SceneState(self)

    def restore_state(self, scene_state: SceneState):
        scene_state.restore_scene(self)

    def save_state(self) -> None:
        if not self.preview:
            return
        state = self.get_state()
        if self.undo_stack and state.mobjects_match(self.undo_stack[-1]):
            return
        self.redo_stack = []
        self.undo_stack.append(state)
        if len(self.undo_stack) > self.max_num_saved_states:
            self.undo_stack.pop(0)

    def undo(self):
        if self.undo_stack:
            self.redo_stack.append(self.get_state())
            self.restore_state(self.undo_stack.pop())
        self.refresh_static_mobjects()

    def redo(self):
        if self.redo_stack:
            self.undo_stack.append(self.get_state())
            self.restore_state(self.redo_stack.pop())
        self.refresh_static_mobjects()

    def checkpoint(self, key: str):
        self.checkpoint_states[key] = self.get_state()

    def revert_to_checkpoint(self, key: str):
        if key not in self.checkpoint_states:
            log.error(f"No checkpoint at {key}")
            return
        all_keys = list(self.checkpoint_states.keys())
        index = all_keys.index(key)
        for later_key in all_keys[index + 1:]:
            self.checkpoint_states.pop(later_key)

        self.restore_state(self.checkpoint_states[key])

    def clear_checkpoints(self):
        self.checkpoint_states = dict()

    def save_mobject_to_file(self, mobject: Mobject, file_path: str | None = None) -> None:
        if file_path is None:
            file_path = self.file_writer.get_saved_mobject_path(mobject)
            if file_path is None:
                return
        mobject.save_to_file(file_path)

    def load_mobject(self, file_name):
        if os.path.exists(file_name):
            path = file_name
        else:
            directory = self.file_writer.get_saved_mobject_directory()
            path = os.path.join(directory, file_name)
        return Mobject.load(path)

    def is_window_closing(self):
        return self.window and (self.window.is_closing or self.quit_interaction)

    # Event handling

    def on_mouse_motion(
        self,
        point: np.ndarray,
        d_point: np.ndarray
    ) -> None:
        self.mouse_point.move_to(point)

        event_data = {"point": point, "d_point": d_point}
        propagate_event = EVENT_DISPATCHER.dispatch(EventType.MouseMotionEvent, **event_data)
        if propagate_event is not None and propagate_event is False:
            return

        frame = self.camera.frame
        # Handle perspective changes
        if self.window.is_key_pressed(ord(PAN_3D_KEY)):
            frame.increment_theta(-self.pan_sensitivity * d_point[0])
            frame.increment_phi(self.pan_sensitivity * d_point[1])
        # Handle frame movements
        elif self.window.is_key_pressed(ord(FRAME_SHIFT_KEY)):
            shift = -d_point
            shift[0] *= frame.get_width() / 2
            shift[1] *= frame.get_height() / 2
            transform = frame.get_inverse_camera_rotation_matrix()
            shift = np.dot(np.transpose(transform), shift)
            frame.shift(shift)

    def on_mouse_drag(
        self,
        point: np.ndarray,
        d_point: np.ndarray,
        buttons: int,
        modifiers: int
    ) -> None:
        self.mouse_drag_point.move_to(point)

        event_data = {"point": point, "d_point": d_point, "buttons": buttons, "modifiers": modifiers}
        propagate_event = EVENT_DISPATCHER.dispatch(EventType.MouseDragEvent, **event_data)
        if propagate_event is not None and propagate_event is False:
            return

    def on_mouse_press(
        self,
        point: np.ndarray,
        button: int,
        mods: int
    ) -> None:
        self.mouse_drag_point.move_to(point)
        event_data = {"point": point, "button": button, "mods": mods}
        propagate_event = EVENT_DISPATCHER.dispatch(EventType.MousePressEvent, **event_data)
        if propagate_event is not None and propagate_event is False:
            return

    def on_mouse_release(
        self,
        point: np.ndarray,
        button: int,
        mods: int
    ) -> None:
        event_data = {"point": point, "button": button, "mods": mods}
        propagate_event = EVENT_DISPATCHER.dispatch(EventType.MouseReleaseEvent, **event_data)
        if propagate_event is not None and propagate_event is False:
            return

    def on_mouse_scroll(
        self,
        point: np.ndarray,
        offset: np.ndarray
    ) -> None:
        event_data = {"point": point, "offset": offset}
        propagate_event = EVENT_DISPATCHER.dispatch(EventType.MouseScrollEvent, **event_data)
        if propagate_event is not None and propagate_event is False:
            return

        frame = self.camera.frame
        if self.window.is_key_pressed(ord(ZOOM_KEY)):
            factor = 1 + np.arctan(10 * offset[1])
            frame.scale(1 / factor, about_point=point)
        else:
            transform = frame.get_inverse_camera_rotation_matrix()
            shift = np.dot(np.transpose(transform), offset)
            frame.shift(-20.0 * shift)

    def on_key_release(
        self,
        symbol: int,
        modifiers: int
    ) -> None:
        event_data = {"symbol": symbol, "modifiers": modifiers}
        propagate_event = EVENT_DISPATCHER.dispatch(EventType.KeyReleaseEvent, **event_data)
        if propagate_event is not None and propagate_event is False:
            return

    def on_key_press(
        self,
        symbol: int,
        modifiers: int
    ) -> None:
        try:
            char = chr(symbol)
        except OverflowError:
            log.warning("The value of the pressed key is too large.")
            return

        event_data = {"symbol": symbol, "modifiers": modifiers}
        propagate_event = EVENT_DISPATCHER.dispatch(EventType.KeyPressEvent, **event_data)
        if propagate_event is not None and propagate_event is False:
            return

        if char == RESET_FRAME_KEY:
            self.play(self.camera.frame.animate.to_default_state())
        elif char == "z" and modifiers == COMMAND_MODIFIER:
            self.undo()
        elif char == "z" and modifiers == COMMAND_MODIFIER | SHIFT_MODIFIER:
            self.redo()
        # command + q
        elif char == QUIT_KEY and modifiers == COMMAND_MODIFIER:
            self.quit_interaction = True
        # Space or right arrow
        elif char == " " or symbol == ARROW_SYMBOLS[2]:
            self.hold_on_wait = False

    def on_resize(self, width: int, height: int) -> None:
        self.camera.reset_pixel_shape(width, height)

    def on_show(self) -> None:
        pass

    def on_hide(self) -> None:
        pass

    def on_close(self) -> None:
        pass


class SceneState():
    def __init__(self, scene: Scene, ignore: list[Mobject] | None = None):
        self.time = scene.time
        self.num_plays = scene.num_plays
        self.mobjects_to_copies = OrderedDict.fromkeys(scene.mobjects)
        if ignore:
            for mob in ignore:
                self.mobjects_to_copies.pop(mob, None)

        last_m2c = scene.undo_stack[-1].mobjects_to_copies if scene.undo_stack else dict()
        for mob in self.mobjects_to_copies:
            # If it hasn't changed since the last state, just point to the
            # same copy as before
            if mob in last_m2c and last_m2c[mob].looks_identical(mob):
                self.mobjects_to_copies[mob] = last_m2c[mob]
            else:
                self.mobjects_to_copies[mob] = mob.copy()

    def __eq__(self, state: SceneState):
        return all((
            self.time == state.time,
            self.num_plays == state.num_plays,
            self.mobjects_to_copies == state.mobjects_to_copies
        ))

    def mobjects_match(self, state: SceneState):
        return self.mobjects_to_copies == state.mobjects_to_copies

    def n_changes(self, state: SceneState):
        m2c = state.mobjects_to_copies
        return sum(
            1 - int(mob in m2c and mob.looks_identical(m2c[mob]))
            for mob in self.mobjects_to_copies
        )

    def restore_scene(self, scene: Scene):
        scene.time = self.time
        scene.num_plays = self.num_plays
        scene.mobjects = [
            mob.become(mob_copy)
            for mob, mob_copy in self.mobjects_to_copies.items()
        ]


class EndScene(Exception):
    pass