"""Fading in and out of view.
.. manim:: Fading
class Fading(Scene):
def construct(self):
tex_in = Tex("Fade", "In").scale(3)
tex_out = Tex("Fade", "Out").scale(3)
self.play(FadeIn(tex_in, shift=DOWN, scale=0.66))
self.play(ReplacementTransform(tex_in, tex_out))
self.play(FadeOut(tex_out, shift=DOWN * 2, scale=1.5))
"""
from __future__ import annotations
__all__ = [
"FadeOut",
"FadeIn",
]
import numpy as np
from manim.mobject.opengl.opengl_mobject import OpenGLMobject
from ..animation.transform import Transform
from ..constants import ORIGIN
from ..mobject.mobject import Group, Mobject
from ..scene.scene import Scene
class _Fade(Transform):
"""Fade :class:`~.Mobject` s in or out.
Parameters
----------
mobjects
The mobjects to be faded.
shift
The vector by which the mobject shifts while being faded.
target_position
The position to/from which the mobject moves while being faded in. In case
another mobject is given as target position, its center is used.
scale
The factor by which the mobject is scaled initially before being rescaling to
its original size while being faded in.
"""
def __init__(
self,
*mobjects: Mobject,
shift: np.ndarray | None = None,
target_position: np.ndarray | Mobject | None = None,
scale: float = 1,
**kwargs,
) -> None:
if not mobjects:
raise ValueError("At least one mobject must be passed.")
if len(mobjects) == 1:
mobject = mobjects[0]
else:
mobject = Group(*mobjects)
self.point_target = False
if shift is None:
if target_position is not None:
if isinstance(target_position, (Mobject, OpenGLMobject)):
target_position = target_position.get_center()
shift = target_position - mobject.get_center()
self.point_target = True
else:
shift = ORIGIN
self.shift_vector = shift
self.scale_factor = scale
super().__init__(mobject, **kwargs)
def _create_faded_mobject(self, fadeIn: bool) -> Mobject:
"""Create a faded, shifted and scaled copy of the mobject.
Parameters
----------
fadeIn
Whether the faded mobject is used to fade in.
Returns
-------
Mobject
The faded, shifted and scaled copy of the mobject.
"""
faded_mobject = self.mobject.copy()
faded_mobject.fade(1)
direction_modifier = -1 if fadeIn and not self.point_target else 1
faded_mobject.shift(self.shift_vector * direction_modifier)
faded_mobject.scale(self.scale_factor)
return faded_mobject
[docs]class FadeIn(_Fade):
"""Fade in :class:`~.Mobject` s.
Parameters
----------
mobjects
The mobjects to be faded in.
shift
The vector by which the mobject shifts while being faded in.
target_position
The position from which the mobject starts while being faded in. In case
another mobject is given as target position, its center is used.
scale
The factor by which the mobject is scaled initially before being rescaling to
its original size while being faded in.
Examples
--------
.. manim :: FadeInExample
class FadeInExample(Scene):
def construct(self):
dot = Dot(UP * 2 + LEFT)
self.add(dot)
tex = Tex(
"FadeIn with ", "shift ", " or target\\_position", " and scale"
).scale(1)
animations = [
FadeIn(tex[0]),
FadeIn(tex[1], shift=DOWN),
FadeIn(tex[2], target_position=dot),
FadeIn(tex[3], scale=1.5),
]
self.play(AnimationGroup(*animations, lag_ratio=0.5))
"""
def __init__(self, *mobjects: Mobject, **kwargs) -> None:
super().__init__(*mobjects, introducer=True, **kwargs)
def create_target(self):
return self.mobject
def create_starting_mobject(self):
return self._create_faded_mobject(fadeIn=True)
[docs]class FadeOut(_Fade):
"""Fade out :class:`~.Mobject` s.
Parameters
----------
mobjects
The mobjects to be faded out.
shift
The vector by which the mobject shifts while being faded out.
target_position
The position to which the mobject moves while being faded out. In case another
mobject is given as target position, its center is used.
scale
The factor by which the mobject is scaled while being faded out.
Examples
--------
.. manim :: FadeInExample
class FadeInExample(Scene):
def construct(self):
dot = Dot(UP * 2 + LEFT)
self.add(dot)
tex = Tex(
"FadeOut with ", "shift ", " or target\\_position", " and scale"
).scale(1)
animations = [
FadeOut(tex[0]),
FadeOut(tex[1], shift=DOWN),
FadeOut(tex[2], target_position=dot),
FadeOut(tex[3], scale=0.5),
]
self.play(AnimationGroup(*animations, lag_ratio=0.5))
"""
def __init__(self, *mobjects: Mobject, **kwargs) -> None:
super().__init__(*mobjects, remover=True, **kwargs)
def create_target(self):
return self._create_faded_mobject(fadeIn=False)
[docs] def clean_up_from_scene(self, scene: Scene = None) -> None:
super().clean_up_from_scene(scene)
self.interpolate(0)