mirror of
https://github.com/3b1b/manim.git
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202 lines
6.6 KiB
Python
202 lines
6.6 KiB
Python
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from big_ol_pile_of_manim_imports import *
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class ConnectionToOptics(Scene):
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def construct(self):
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e_group, m_group = k_groups = self.get_kinematics_groups()
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c_group, a_group = o_groups = self.get_optics_groups()
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arrows = VGroup()
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for g1, g2 in zip(k_groups, o_groups):
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g2.align_to(g1, UP)
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g2.to_edge(RIGHT)
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arrow = TexMobject("\\Rightarrow")
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arrow.scale(1.5)
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arrow.move_to(interpolate(
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g1[0].get_right(), g2[0].get_left(), 0.5
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))
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arrows.add(arrow)
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everything = VGroup(k_groups, arrows, o_groups)
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everything.to_edge(UP)
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everything.generate_target()
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everything.target.scale(0.9)
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everything.target.to_edge(DOWN)
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width = max([m.get_width() for m in everything.target])
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width += 2 * MED_SMALL_BUFF
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rects = VGroup()
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for k in [0, 2]:
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rect = DashedMobject(Rectangle(
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height=FRAME_HEIGHT - 1.5,
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width=width
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), dashes_num=100)
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rect.move_to(everything.target[k])
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rect.to_edge(DOWN, buff=SMALL_BUFF)
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rects.add(rect)
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titles = VGroup(
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TextMobject("Kinematics"),
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TextMobject("Optics"),
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)
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titles.scale(1.5)
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for title, rect in zip(titles, rects):
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title.next_to(rect, UP)
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titles[0].align_to(titles[1], UP)
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self.play(FadeInFromDown(e_group))
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self.play(
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Write(arrows[0]),
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FadeInFrom(c_group, LEFT)
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)
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self.wait()
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self.play(FadeInFromDown(m_group))
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self.play(
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Write(arrows[1]),
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FadeInFrom(a_group, LEFT)
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)
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self.wait(4)
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for k in range(2):
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anims = [
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ShowCreation(rects[k]),
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FadeInFromDown(titles[k]),
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]
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if k == 0:
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anims.append(MoveToTarget(everything))
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self.play(*anims)
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self.wait()
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self.wait()
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self.wait(4)
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def get_kinematics_groups(self):
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tex_to_color_map = {
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"m_1": BLUE,
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"m_2": BLUE,
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"v_1": RED,
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"v_2": RED,
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}
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energy_eq = TexMobject(
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"\\frac{1}{2} m_1 (v_1)^2 + "
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"\\frac{1}{2} m_2 (v_2)^2 = "
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"\\text{const.}",
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tex_to_color_map=tex_to_color_map
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)
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energy_eq.scale(0.8)
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momentum_eq = TexMobject(
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"m_1 v_1 + m_2 v_2 = \\text{const.}",
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tex_to_color_map=tex_to_color_map
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)
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energy_label = TextMobject(
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"Conservation of energy"
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)
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momentum_label = TextMobject(
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"Conservation of momentum"
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)
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energy_group = VGroup(energy_label, energy_eq)
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momentum_group = VGroup(momentum_label, momentum_eq)
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groups = VGroup(energy_group, momentum_group)
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for group in groups:
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group.arrange_submobjects(DOWN, buff=MED_LARGE_BUFF)
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group[0].set_color(GREEN)
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groups.arrange_submobjects(DOWN, buff=2)
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groups.to_edge(LEFT)
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return groups
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def get_optics_groups(self):
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self.time_tracker = ValueTracker(0)
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self.time_tracker.add_updater(
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lambda m, dt: m.increment_value(dt)
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)
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self.add(self.time_tracker)
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return VGroup(
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self.get_speed_group(),
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self.get_angle_group()
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)
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def get_speed_group(self):
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speed_label = TextMobject("Constant speed of light")
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speed_label.set_color(YELLOW)
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speed_light_template = Line(LEFT, RIGHT)
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speed_light_template.fade(1)
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speed_light_template.match_width(speed_label)
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speed_light_template.next_to(speed_label, DOWN, MED_LARGE_BUFF)
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speed_light = speed_light_template.deepcopy()
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def update_speed_light(light, period=2, time_width=0.05):
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time = self.time_tracker.get_value()
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alpha = (time / period) % 1
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# alpha = 1 - 2 * abs(alpha - 0.5)
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alpha *= 1.5
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a = alpha - time_width / 2
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b = alpha + time_width / 2
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light.pointwise_become_partial(
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speed_light_template, max(a, 0), min(b, 1)
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)
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opacity = speed_label.family_members_with_points()[0].get_fill_opacity()
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light.set_stroke(YELLOW, width=3, opacity=opacity)
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# light.stretch(0.5, 0)
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# point = speed_light_template.point_from_proportion(0.25)
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# light.stretch(2, 0, about_point=point)
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speed_light.add_updater(update_speed_light)
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result = VGroup(
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speed_label, speed_light_template, speed_light
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)
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return result
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def get_angle_group(self):
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title = VGroup(*map(TextMobject, [
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"Angle of\\\\Incidence",
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"=",
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"Angle of\\\\Refraction",
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])).arrange_submobjects(RIGHT)
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title.set_color(YELLOW)
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h_line = Line(LEFT, RIGHT)
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h_line.match_width(title)
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h_line.set_stroke(LIGHT_GREY)
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h_line.set_sheen(1, UL)
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points = [
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h_line.get_left() + UP,
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h_line.get_center(),
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h_line.get_right() + UP,
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]
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dashed_lines = VGroup(
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DashedLine(*points[0:2]), DashedLine(*points[1:3])
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)
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dashed_lines.set_stroke(WHITE, 2)
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v_shape = VMobject()
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v_shape.set_points_as_corners(points)
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v_shape.fade(1)
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theta = dashed_lines[1].get_angle()
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arcs = VGroup(
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Arc(start_angle=0, angle=theta),
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Arc(start_angle=PI, angle=-theta),
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)
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arcs.set_stroke(WHITE, 2)
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thetas = VGroup()
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for v in LEFT, RIGHT:
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theta = TexMobject("\\theta")
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theta.next_to(arcs, v, aligned_edge=DOWN)
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theta.shift(SMALL_BUFF * UP)
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thetas.add(theta)
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beam = VMobject()
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def update_beam(beam, period=2, time_width=0.05):
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time = self.time_tracker.get_value()
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alpha = (time / period) % 1
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alpha *= 1.5
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a = alpha - time_width / 2
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b = alpha + time_width / 2
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beam.pointwise_become_partial(
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v_shape, max(a, 0), min(b, 1)
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)
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opacity = title.family_members_with_points()[0].get_fill_opacity()
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beam.set_stroke(YELLOW, width=3, opacity=opacity)
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beam.add_updater(update_beam)
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title.next_to(v_shape, UP, MED_LARGE_BUFF)
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return VGroup(
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title, h_line, arcs, thetas,
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dashed_lines, v_shape, beam
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)
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