3b1b-manim/manimlib/animation/fading.py

148 lines
4 KiB
Python

from manimlib.animation.animation import Animation
from manimlib.animation.transform import Transform
from manimlib.mobject.mobject import Group
from manimlib.constants import ORIGIN
from manimlib.utils.bezier import interpolate
from manimlib.utils.rate_functions import there_and_back
DEFAULT_FADE_LAG_RATIO = 0
class Fade(Transform):
CONFIG = {
"lag_ratio": DEFAULT_FADE_LAG_RATIO,
}
def __init__(self, mobject, shift=ORIGIN, scale=1, **kwargs):
self.shift_vect = shift
self.scale_factor = scale
super().__init__(mobject, **kwargs)
class FadeIn(Fade):
CONFIG = {
"lag_ratio": DEFAULT_FADE_LAG_RATIO,
}
def create_target(self):
return self.mobject
def create_starting_mobject(self):
start = super().create_starting_mobject()
start.set_opacity(0)
start.scale(1.0 / self.scale_factor)
start.shift(-self.shift_vect)
return start
class FadeOut(Fade):
CONFIG = {
"remover": True,
# Put it back in original state when done
"final_alpha_value": 0,
}
def create_target(self):
result = self.mobject.copy()
result.set_opacity(0)
result.shift(self.shift_vect)
result.scale(self.scale_factor)
return result
class FadeInFromPoint(FadeIn):
def __init__(self, mobject, point, **kwargs):
super().__init__(mobject, shift=mobject.get_center() - point, **kwargs)
class FadeTransform(Transform):
CONFIG = {
"stretch": True,
"dim_to_match": 1,
}
def __init__(self, mobject, target_mobject, **kwargs):
self.to_add_on_completion = target_mobject
mobject.save_state()
super().__init__(
Group(mobject, target_mobject.copy()),
**kwargs
)
def begin(self):
self.ending_mobject = self.mobject.copy()
Animation.begin(self)
# Both 'start' and 'end' consists of the source and target mobjects.
# At the start, the traget should be faded replacing the source,
# and at the end it should be the other way around.
start, end = self.starting_mobject, self.ending_mobject
for m0, m1 in ((start[1], start[0]), (end[0], end[1])):
self.ghost_to(m0, m1)
def ghost_to(self, source, target):
source.replace(target, stretch=self.stretch, dim_to_match=self.dim_to_match)
source.set_opacity(0)
def get_all_mobjects(self):
return [
self.mobject,
self.starting_mobject,
self.ending_mobject,
]
def get_all_families_zipped(self):
return Animation.get_all_families_zipped(self)
def clean_up_from_scene(self, scene):
Animation.clean_up_from_scene(self, scene)
scene.remove(self.mobject)
self.mobject[0].restore()
scene.add(self.to_add_on_completion)
class FadeTransformPieces(FadeTransform):
def begin(self):
self.mobject[0].align_data(self.mobject[1])
super().begin()
def ghost_to(self, source, target):
for sm0, sm1 in zip(source.get_family(), target.get_family()):
super().ghost_to(sm0, sm1)
class VFadeIn(Animation):
"""
VFadeIn and VFadeOut only work for VMobjects,
"""
CONFIG = {
"suspend_mobject_updating": False,
}
def interpolate_submobject(self, submob, start, alpha):
submob.set_stroke(
opacity=interpolate(0, start.get_stroke_opacity(), alpha)
)
submob.set_fill(
opacity=interpolate(0, start.get_fill_opacity(), alpha)
)
class VFadeOut(VFadeIn):
CONFIG = {
"remover": True,
# Put it back in original state when done
"final_alpha_value": 0,
}
def interpolate_submobject(self, submob, start, alpha):
super().interpolate_submobject(submob, start, 1 - alpha)
class VFadeInThenOut(VFadeIn):
CONFIG = {
"rate_func": there_and_back,
"remover": True,
# Put it back in original state when done
"final_alpha_value": 0.5,
}