3b1b-manim/manimlib/mobject/vector_field.py
2022-02-16 21:08:25 +08:00

337 lines
10 KiB
Python

from __future__ import annotations
import itertools as it
import random
from typing import Sequence, TypeVar, Callable, Iterable
import numpy as np
import numpy.typing as npt
from manimlib.constants import *
from manimlib.animation.composition import AnimationGroup
from manimlib.animation.indication import VShowPassingFlash
from manimlib.mobject.geometry import Arrow
from manimlib.mobject.types.vectorized_mobject import VGroup
from manimlib.mobject.types.vectorized_mobject import VMobject
from manimlib.utils.bezier import inverse_interpolate
from manimlib.utils.bezier import interpolate
from manimlib.utils.color import get_colormap_list
from manimlib.utils.config_ops import merge_dicts_recursively
from manimlib.utils.config_ops import digest_config
from manimlib.utils.rate_functions import linear
from manimlib.utils.simple_functions import sigmoid
from manimlib.utils.space_ops import get_norm
from typing import TYPE_CHECKING
if TYPE_CHECKING:
from manimlib.mobject.mobject import Mobject
from manimlib.mobject.coordinate_systems import CoordinateSystem
T = TypeVar("T")
def get_vectorized_rgb_gradient_function(
min_value: T,
max_value: T,
color_map: str
) -> Callable[[npt.ArrayLike], np.ndarray]:
rgbs = np.array(get_colormap_list(color_map))
def func(values):
alphas = inverse_interpolate(
min_value, max_value, np.array(values)
)
alphas = np.clip(alphas, 0, 1)
scaled_alphas = alphas * (len(rgbs) - 1)
indices = scaled_alphas.astype(int)
next_indices = np.clip(indices + 1, 0, len(rgbs) - 1)
inter_alphas = scaled_alphas % 1
inter_alphas = inter_alphas.repeat(3).reshape((len(indices), 3))
result = interpolate(rgbs[indices], rgbs[next_indices], inter_alphas)
return result
return func
def get_rgb_gradient_function(
min_value: T,
max_value: T,
color_map: str
) -> Callable[[T], np.ndarray]:
vectorized_func = get_vectorized_rgb_gradient_function(min_value, max_value, color_map)
return lambda value: vectorized_func([value])[0]
def move_along_vector_field(
mobject: Mobject,
func: Callable[[np.ndarray], np.ndarray]
) -> Mobject:
mobject.add_updater(
lambda m, dt: m.shift(
func(m.get_center()) * dt
)
)
return mobject
def move_submobjects_along_vector_field(
mobject: Mobject,
func: Callable[[np.ndarray], np.ndarray]
) -> Mobject:
def apply_nudge(mob, dt):
for submob in mob:
x, y = submob.get_center()[:2]
if abs(x) < FRAME_WIDTH and abs(y) < FRAME_HEIGHT:
submob.shift(func(submob.get_center()) * dt)
mobject.add_updater(apply_nudge)
return mobject
def move_points_along_vector_field(
mobject: Mobject,
func: Callable[[float, float], Iterable[float]],
coordinate_system: CoordinateSystem
) -> Mobject:
cs = coordinate_system
origin = cs.get_origin()
def apply_nudge(self, dt):
mobject.apply_function(
lambda p: p + (cs.c2p(*func(*cs.p2c(p))) - origin) * dt
)
mobject.add_updater(apply_nudge)
return mobject
def get_sample_points_from_coordinate_system(
coordinate_system: CoordinateSystem,
step_multiple: float
) -> it.product[tuple[np.ndarray, ...]]:
ranges = []
for range_args in coordinate_system.get_all_ranges():
_min, _max, step = range_args
step *= step_multiple
ranges.append(np.arange(_min, _max + step, step))
return it.product(*ranges)
# Mobjects
class VectorField(VGroup):
CONFIG = {
"step_multiple": 0.5,
"magnitude_range": (0, 2),
"color_map": "3b1b_colormap",
# Takes in actual norm, spits out displayed norm
"length_func": lambda norm: 0.45 * sigmoid(norm),
"opacity": 1.0,
"vector_config": {},
}
def __init__(
self,
func: Callable[[float, float], Sequence[float]],
coordinate_system: CoordinateSystem,
**kwargs
):
super().__init__(**kwargs)
self.func = func
self.coordinate_system = coordinate_system
self.value_to_rgb = get_rgb_gradient_function(
*self.magnitude_range, self.color_map,
)
samples = get_sample_points_from_coordinate_system(
coordinate_system, self.step_multiple
)
self.add(*(
self.get_vector(coords)
for coords in samples
))
def get_vector(self, coords: Iterable[float], **kwargs) -> Arrow:
vector_config = merge_dicts_recursively(
self.vector_config,
kwargs
)
output = np.array(self.func(*coords))
norm = get_norm(output)
if norm > 0:
output *= self.length_func(norm) / norm
origin = self.coordinate_system.get_origin()
_input = self.coordinate_system.c2p(*coords)
_output = self.coordinate_system.c2p(*output)
vect = Arrow(
origin, _output, buff=0,
**vector_config
)
vect.shift(_input - origin)
vect.set_rgba_array([[*self.value_to_rgb(norm), self.opacity]])
return vect
class StreamLines(VGroup):
CONFIG = {
"step_multiple": 0.5,
"n_repeats": 1,
"noise_factor": None,
# Config for drawing lines
"dt": 0.05,
"arc_len": 3,
"max_time_steps": 200,
"n_samples_per_line": 10,
"cutoff_norm": 15,
# Style info
"stroke_width": 1,
"stroke_color": WHITE,
"stroke_opacity": 1,
"color_by_magnitude": True,
"magnitude_range": (0, 2.0),
"taper_stroke_width": False,
"color_map": "3b1b_colormap",
}
def __init__(
self,
func: Callable[[float, float], Sequence[float]],
coordinate_system: CoordinateSystem,
**kwargs
):
super().__init__(**kwargs)
self.func = func
self.coordinate_system = coordinate_system
self.draw_lines()
self.init_style()
def point_func(self, point: np.ndarray) -> np.ndarray:
in_coords = self.coordinate_system.p2c(point)
out_coords = self.func(*in_coords)
return self.coordinate_system.c2p(*out_coords)
def draw_lines(self) -> None:
lines = []
origin = self.coordinate_system.get_origin()
for point in self.get_start_points():
points = [point]
total_arc_len = 0
time = 0
for x in range(self.max_time_steps):
time += self.dt
last_point = points[-1]
new_point = last_point + self.dt * (self.point_func(last_point) - origin)
points.append(new_point)
total_arc_len += get_norm(new_point - last_point)
if get_norm(last_point) > self.cutoff_norm:
break
if total_arc_len > self.arc_len:
break
line = VMobject()
line.virtual_time = time
step = max(1, int(len(points) / self.n_samples_per_line))
line.set_points_as_corners(points[::step])
line.make_approximately_smooth()
lines.append(line)
self.set_submobjects(lines)
def get_start_points(self) -> np.ndarray:
cs = self.coordinate_system
sample_coords = get_sample_points_from_coordinate_system(
cs, self.step_multiple,
)
noise_factor = self.noise_factor
if noise_factor is None:
noise_factor = cs.x_range[2] * self.step_multiple * 0.5
return np.array([
cs.c2p(*coords) + noise_factor * np.random.random(3)
for n in range(self.n_repeats)
for coords in sample_coords
])
def init_style(self) -> None:
if self.color_by_magnitude:
values_to_rgbs = get_vectorized_rgb_gradient_function(
*self.magnitude_range, self.color_map,
)
cs = self.coordinate_system
for line in self.submobjects:
norms = [
get_norm(self.func(*cs.p2c(point)))
for point in line.get_points()
]
rgbs = values_to_rgbs(norms)
rgbas = np.zeros((len(rgbs), 4))
rgbas[:, :3] = rgbs
rgbas[:, 3] = self.stroke_opacity
line.set_rgba_array(rgbas, "stroke_rgba")
else:
self.set_stroke(self.stroke_color, opacity=self.stroke_opacity)
if self.taper_stroke_width:
width = [0, self.stroke_width, 0]
else:
width = self.stroke_width
self.set_stroke(width=width)
class AnimatedStreamLines(VGroup):
CONFIG = {
"lag_range": 4,
"line_anim_class": VShowPassingFlash,
"line_anim_config": {
# "run_time": 4,
"rate_func": linear,
"time_width": 0.5,
},
}
def __init__(self, stream_lines: StreamLines, **kwargs):
super().__init__(**kwargs)
self.stream_lines = stream_lines
for line in stream_lines:
line.anim = self.line_anim_class(
line,
run_time=line.virtual_time,
**self.line_anim_config,
)
line.anim.begin()
line.time = -self.lag_range * random.random()
self.add(line.anim.mobject)
self.add_updater(lambda m, dt: m.update(dt))
def update(self, dt: float) -> None:
stream_lines = self.stream_lines
for line in stream_lines:
line.time += dt
adjusted_time = max(line.time, 0) % line.anim.run_time
line.anim.update(adjusted_time / line.anim.run_time)
# TODO: This class should be deleted
class ShowPassingFlashWithThinningStrokeWidth(AnimationGroup):
CONFIG = {
"n_segments": 10,
"time_width": 0.1,
"remover": True
}
def __init__(self, vmobject: VMobject, **kwargs):
digest_config(self, kwargs)
max_stroke_width = vmobject.get_stroke_width()
max_time_width = kwargs.pop("time_width", self.time_width)
AnimationGroup.__init__(self, *[
VShowPassingFlash(
vmobject.deepcopy().set_stroke(width=stroke_width),
time_width=time_width,
**kwargs
)
for stroke_width, time_width in zip(
np.linspace(0, max_stroke_width, self.n_segments),
np.linspace(max_time_width, 0, self.n_segments)
)
])