mirror of
https://github.com/3b1b/videos.git
synced 2025-08-31 21:58:59 +00:00
64 lines
2.2 KiB
Python
64 lines
2.2 KiB
Python
from manim_imports_ext import *
|
|
|
|
|
|
class RotatingButterflyCurve(Animation):
|
|
"""
|
|
Pretty hacky, but should only be redone in the context
|
|
of a broader 4d mobject class
|
|
"""
|
|
CONFIG = {
|
|
"space_epsilon": 0.002,
|
|
"grid_line_sep": 0.2,
|
|
"radius": 2,
|
|
"radians": 2 * np.pi,
|
|
"run_time": 15,
|
|
"rate_func": linear,
|
|
}
|
|
|
|
def __init__(self, **kwargs):
|
|
digest_config(self, kwargs)
|
|
fine_range = np.arange(-self.radius, self.radius, self.space_epsilon)
|
|
corse_range = np.arange(-self.radius, self.radius, self.grid_line_sep)
|
|
self.points = np.array([
|
|
[x, y, x * x, y * y]
|
|
for a in fine_range
|
|
for b in corse_range
|
|
for x, y in [(a, b), (b, a)]
|
|
])
|
|
graph_rgb = Color(TEAL).get_rgb()
|
|
self.rgbas = np.array([graph_rgb] * len(self.points))
|
|
colors = iter([YELLOW_A, YELLOW_B, YELLOW_C, YELLOW_D])
|
|
for i in range(4):
|
|
vect = np.zeros(4)
|
|
vect[i] = 1
|
|
line_range = np.arange(-FRAME_Y_RADIUS,
|
|
FRAME_Y_RADIUS, self.space_epsilon)
|
|
self.points = np.append(self.points, [
|
|
x * vect
|
|
for x in line_range
|
|
], axis=0)
|
|
axis_rgb = Color(next(colors)).get_rgb()
|
|
self.rgbas = np.append(
|
|
self.rgbas, [axis_rgb] * len(line_range), axis=0)
|
|
|
|
self.quads = [(0, 1, 2, 3), (0, 1, 0, 1), (3, 2, 1, 0)]
|
|
self.multipliers = [0.9, 1, 1.1]
|
|
Animation.__init__(self, Mobject(), **kwargs)
|
|
|
|
def interpolate_mobject(self, alpha):
|
|
angle = alpha * self.radians
|
|
rot_matrix = np.identity(4)
|
|
for quad, mult in zip(self.quads, self.multipliers):
|
|
base = np.identity(4)
|
|
theta = mult * angle
|
|
base[quad[:2], quad[2]] = [np.cos(theta), np.sin(theta)]
|
|
base[quad[:2], quad[3]] = [-np.sin(theta), np.cos(theta)]
|
|
rot_matrix = np.dot(rot_matrix, base)
|
|
points = np.dot(self.points, np.transpose(rot_matrix))
|
|
self.mobject.points = points[:, :3]
|
|
self.mobject.rgbas = self.rgbas
|
|
|
|
|
|
class RotatingFourDButterflyCurve(Scene):
|
|
def construct(self):
|
|
self.play(RotatingButterflyCurve())
|