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More pendulum scenesw

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This commit is contained in:
Grant Sanderson 2019-03-20 13:07:53 -07:00
parent 0271511a9e
commit a320d9a47e
2 changed files with 185 additions and 16 deletions
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8
active_projects/ode/all_part1_scenes.py
View file

@ -4,12 +4,12 @@ from active_projects.ode.part1.staging import *
OUTPUT_DIRECTORY = "ode/part1"
ALL_SCENE_CLASSES = [
IntroducePendulum,
FormulasAreLies,
HighAnglePendulum,
MultiplePendulumsOverlayed,
# FormulasAreLies,
MediumAnglePendulum,
MediumHighAnglePendulum,
HighAnglePendulum,
LowAnglePendulum,
ApproxWordsLowAnglePendulum,
FailedApproxWordsHighAnglePendulum,
# Tests
PendulumTest,
VectorFieldTest,

193
active_projects/ode/part1/pendulum.py
View file

@ -237,6 +237,8 @@ class ThetaVsTAxes(Axes):
},
"number_line_config": {
"color": "#EEEEEE",
"stroke_width": 2,
"include_tip": False,
},
"graph_style": {
"stroke_color": GREEN,
@ -262,7 +264,7 @@ class ThetaVsTAxes(Axes):
x_axis.label = t_label
x_axis.add(t_label)
theta_label = self.theta_label = TexMobject("\\theta(t)")
theta_label.next_to(y_axis.get_top(), RIGHT, MED_SMALL_BUFF)
theta_label.next_to(y_axis.get_top(), UP, SMALL_BUFF)
y_axis.label = theta_label
y_axis.add(theta_label)
@ -330,23 +332,48 @@ class ThetaVsTAxes(Axes):
# Scenes
class IntroducePendulum(MovingCameraScene):
class IntroducePendulum(PiCreatureScene, MovingCameraScene):
CONFIG = {
"pendulum_config": {
"length": 3,
"top_point": 4 * RIGHT,
"weight_diameter": 0.35,
},
"theta_vs_t_axes_config": {},
"theta_vs_t_axes_config": {
"y_max": PI / 4,
"y_min": -PI / 4,
"y_axis_config": {
"tick_frequency": PI / 16,
"unit_size": 2,
"tip_length": 0.3,
},
"number_line_config": {
"stroke_width": 2,
}
},
}
def setup(self):
MovingCameraScene.setup(self)
PiCreatureScene.setup(self)
def construct(self):
self.add_pendulum()
self.label_pi_creatures()
self.label_pendulum()
self.add_graph()
self.show_graph_period()
self.show_length_and_gravity()
self.tweak_length_and_gravity()
self.tweak_gravity()
def create_pi_creatures(self):
randy = Randolph(color=BLUE_C)
morty = Mortimer(color=MAROON_E)
creatures = VGroup(randy, morty)
creatures.scale(0.5)
creatures.arrange(RIGHT, buff=2.5)
creatures.to_corner(DR)
return creatures
def add_pendulum(self):
pendulum = self.pendulum = Pendulum(**self.pendulum_config)
@ -356,12 +383,50 @@ class IntroducePendulum(MovingCameraScene):
frame.scale(0.5)
frame.move_to(pendulum.dashed_line)
self.add(pendulum, frame)
def label_pi_creatures(self):
randy, morty = self.pi_creatures
randy_label = TextMobject("Physics\\\\", "student")
morty_label = TextMobject("Physics\\\\", "teacher")
labels = VGroup(randy_label, morty_label)
labels.scale(0.5)
randy_label.next_to(randy, UP, LARGE_BUFF)
morty_label.next_to(morty, UP, LARGE_BUFF)
for label, pi in zip(labels, self.pi_creatures):
label.arrow = Arrow(
label.get_bottom(), pi.eyes.get_top()
)
label.arrow.set_color(WHITE)
label.arrow.set_stroke(width=5)
morty.labels = VGroup(
morty_label,
morty_label.arrow,
)
self.play(
FadeInFromDown(randy_label),
GrowArrow(randy_label.arrow),
randy.change, "hooray",
)
self.play(
Animation(self.pendulum.fixed_point_tracker),
TransformFromCopy(randy_label[0], morty_label[0]),
FadeIn(morty_label[1]),
GrowArrow(morty_label.arrow),
morty.change, "raise_right_hand",
)
self.wait()
def label_pendulum(self):
pendulum = self.pendulum
randy, morty = self.pi_creatures
label = pendulum.theta_label
rect = SurroundingRectangle(label, buff=0.5 * SMALL_BUFF)
rect.add_updater(lambda r: r.move_to(label))
self.add(pendulum)
self.wait(2)
self.add(rect)
self.play(
ShowCreationThenFadeOut(rect),
@ -371,11 +436,15 @@ class IntroducePendulum(MovingCameraScene):
stroke_color=PINK,
stroke_width=2,
)
),
randy.change, "pondering",
morty.change, "pondering",
)
)
self.wait()
def add_graph(self):
axes = self.axes = ThetaVsTAxes(**self.theta_vs_t_axes_config)
axes.y_axis.label.next_to(axes.y_axis, UP, buff=0)
axes.to_corner(UL)
self.play(
@ -393,6 +462,7 @@ class IntroducePendulum(MovingCameraScene):
),
run_time=3,
)
self.wait(2)
self.graph = axes.get_live_drawn_graph(self.pendulum)
self.add(self.graph)
@ -450,13 +520,26 @@ class IntroducePendulum(MovingCameraScene):
)
self.play(ShowCreationThenDestructionAround(L))
self.play(ShowCreation(new_rod))
dot = Dot(fill_opacity=0.25)
dot.move_to(L)
self.play(
ShowCreation(new_rod),
dot.move_to, new_rod,
dot.fade, 1,
)
self.remove(dot)
self.play(FadeOut(new_rod))
self.wait()
self.play(ShowCreationThenDestructionAround(g))
dot.move_to(g)
dot.set_fill(opacity=0.5)
self.play(
ShowCreationThenDestructionAround(g),
GrowArrow(g_vect)
GrowArrow(g_vect),
dot.move_to, g_vect,
dot.fade, 1,
)
self.remove(dot)
self.wait(2)
self.gravity_vector = g_vect
@ -468,6 +551,7 @@ class IntroducePendulum(MovingCameraScene):
brace = self.period_brace
formula = self.period_formula
g_vect = self.gravity_vector
randy, morty = self.pi_creatures
graph.clear_updaters()
period2 = self.period * np.sqrt(2)
@ -500,7 +584,14 @@ class IntroducePendulum(MovingCameraScene):
# vect.shift(0.1 * np.random.random(3))
down_vectors.to_edge(RIGHT)
self.play(ReplacementTransform(pendulum, new_pendulum))
self.play(randy.change, "happy")
self.play(
ReplacementTransform(pendulum, new_pendulum),
morty.change, "horrified",
morty.shift, 3 * RIGHT,
morty.labels.shift, 3 * RIGHT,
)
self.remove(morty, morty.labels)
g_vect.attach_to_pendulum(new_pendulum)
new_pendulum.start_swinging()
self.play(
@ -515,7 +606,7 @@ class IntroducePendulum(MovingCameraScene):
self.play(
FadeOut(graph2),
LaggedStart(*[
FadeIn(v, rate_func=there_and_back)
GrowArrow(v, rate_func=there_and_back)
for v in down_vectors
], lag_ratio=0.0005, run_time=2, remover=True)
)
@ -526,6 +617,75 @@ class IntroducePendulum(MovingCameraScene):
self.wait(6)
class MultiplePendulumsOverlayed(Scene):
CONFIG = {
"initial_thetas": [
150 * DEGREES,
90 * DEGREES,
60 * DEGREES,
30 * DEGREES,
10 * DEGREES,
],
"weight_colors": [
PINK, RED, GREEN, BLUE, GREY,
],
"pendulum_config": {
"top_point": ORIGIN,
"length": 3,
},
}
def construct(self):
pendulums = VGroup(*[
Pendulum(
initial_theta=theta,
weight_style={
"fill_color": wc,
"fill_opacity": 0.5,
},
**self.pendulum_config,
)
for theta, wc in zip(
self.initial_thetas,
self.weight_colors,
)
])
for pendulum in pendulums:
pendulum.start_swinging()
pendulum.remove(pendulum.theta_label)
randy = Randolph(color=BLUE_C)
randy.to_corner(DL)
randy.add_updater(lambda r: r.look_at(pendulums[0].weight))
axes = ThetaVsTAxes(
x_max=20,
y_axis_config={
"unit_size": 0.5,
"tip_length": 0.3,
},
)
axes.to_corner(UL)
graphs = VGroup(*[
axes.get_live_drawn_graph(
pendulum,
stroke_color=pendulum.weight.get_color(),
stroke_width=1,
)
for pendulum in pendulums
])
self.add(pendulums)
self.add(axes, *graphs)
self.play(randy.change, "sassy")
self.wait(2)
self.play(Blink(randy))
self.wait(5)
self.play(randy.change, "angry")
self.play(Blink(randy))
self.wait(10)
class LowAnglePendulum(Scene):
CONFIG = {
"pendulum_config": {
@ -638,6 +798,15 @@ class MediumAnglePendulum(LowAnglePendulum):
}
class MediumHighAnglePendulum(MediumAnglePendulum):
CONFIG = {
"pendulum_config": {
"initial_theta": 90 * DEGREES,
"n_steps_per_frame": 1000,
},
}
class HighAnglePendulum(LowAnglePendulum):
CONFIG = {
"pendulum_config": {