manimの作法 その57

概要

manimの作法、調べてみた。
ComplexPlane、使ってみた。

サンプルコード

from manimlib.imports import *

class test(Scene):
    CONFIG = {
        "axes_config": {
            "x_min": 0,
            "x_max": 10,
            "x_axis_config": {
                "stroke_width": 2,
            },
            "y_min": -2.5,
            "y_max": 2.5,
            "y_axis_config": {
                "tick_frequency": 0.25,
                "unit_size": 1.5,
                "include_tip": False,
                "stroke_width": 2,
            },
        },
        "complex_plane_config": {
            "axis_config": {
                "unit_size": 2
            }
        },
    }
    def construct(self):
        self.show_cosine_wave()
        self.transition_to_complex_plane()
        self.add_rotating_vectors_making_cos()
    def show_cosine_wave(self):
        axes = Axes(**self.axes_config)
        axes.shift(2 * LEFT - axes.c2p(0, 0))
        y_axis = axes.y_axis
        y_labels = y_axis.get_number_mobjects(*range(-2, 3),number_config={"num_decimal_places": 1},)
        t_tracker = ValueTracker(0)
        t_tracker.add_updater(lambda t, dt: t.increment_value(dt))
        get_t = t_tracker.get_value
        def func(x):
            return 2 * np.cos(x)
        cos_x_max = 20
        cos_wave = axes.get_graph(func, x_max=cos_x_max)
        cos_wave.set_color(YELLOW)
        shown_cos_wave = cos_wave.copy()
        shown_cos_wave.add_updater(lambda m: m.pointwise_become_partial(cos_wave, 0,np.clip(get_t() / cos_x_max, 0, 1),),)
        dot = Dot()
        dot.set_color(PINK)
        dot.add_updater(lambda d: d.move_to(y_axis.n2p(func(get_t())),))
        h_line = always_redraw(lambda: Line(dot.get_right(),shown_cos_wave.get_end(),stroke_width=1,))
        real_words = TextMobject("Real number\\\\output")
        real_words.to_edge(LEFT)
        real_words.shift(2 * UP)
        real_arrow = Arrow()
        real_arrow.add_updater(lambda m: m.put_start_and_end_on(real_words.get_corner(DR),dot.get_center(),).scale(0.9),)
        self.add(t_tracker)
        self.add(axes)
        self.add(y_labels)
        self.add(shown_cos_wave)
        self.add(dot)
        self.add(h_line)
        self.wait(2)
        self.play(FadeInFrom(real_words, RIGHT),FadeIn(real_arrow),)
        self.wait(5)
        y_axis.generate_target()
        y_axis.target.rotate(-90 * DEGREES)
        y_axis.target.center()
        y_axis.target.scale(2 / 1.5)
        y_labels.generate_target()
        for label in y_labels.target:
            label.next_to(y_axis.target.n2p(label.get_value()),DOWN, MED_SMALL_BUFF,)
        self.play(FadeOut(shown_cos_wave),FadeOut(axes.x_axis),FadeOut(h_line),)
        self.play(MoveToTarget(y_axis),MoveToTarget(y_labels),real_words.shift, 2 * RIGHT + UP,)
        self.wait()
        self.y_axis = y_axis
        self.y_labels = y_labels
        self.real_words = real_words
        self.real_arrow = real_arrow
        self.dot = dot
        self.t_tracker = t_tracker
    def transition_to_complex_plane(self):
        y_axis = self.y_axis
        y_labels = self.y_labels
        plane = self.get_complex_plane()
        plane_words = plane.label
        self.add(plane, *self.get_mobjects())
        self.play(FadeOut(y_labels),FadeOut(y_axis),ShowCreation(plane),)
        self.play(Write(plane_words))
        self.wait()
        self.plane = plane
        self.plane_words = plane_words
    def add_rotating_vectors_making_cos(self):
        plane = self.plane
        real_words = self.real_words
        real_arrow = self.real_arrow
        t_tracker = self.t_tracker
        get_t = t_tracker.get_value
        v1 = Vector(2 * RIGHT)
        v2 = Vector(2 * RIGHT)
        v1.set_color(BLUE)
        v2.set_color(interpolate_color(GREY_BROWN, WHITE, 0.5))
        v1.add_updater(lambda v: v.set_angle(get_t()))
        v2.add_updater(lambda v: v.set_angle(-get_t()))
        v1.add_updater(lambda v: v.shift(plane.n2p(0) - v.get_start()))
        v2.add_updater(lambda v: v.shift(plane.n2p(0) - v.get_start()))
        ghost_v1 = v1.copy()
        ghost_v1.set_opacity(0.5)
        ghost_v1.add_updater(lambda v: v.shift(v2.get_end() - v.get_start()))
        ghost_v2 = v2.copy()
        ghost_v2.set_opacity(0.5)
        ghost_v2.add_updater(lambda v: v.shift(v1.get_end() - v.get_start()))
        circle = Circle(color=GREY_BROWN)
        circle.set_stroke(width=1)
        circle.set_width(2 * v1.get_length())
        circle.move_to(plane.n2p(0))
        formula = TexMobject("2\\cos(x) =","e^{ix}", "+", "e^{-ix}",tex_to_color_map={
                "e^{ix}": v1.get_color(),
                "e^{-ix}": v2.get_color(),
            })
        formula.next_to(ORIGIN, UP, buff=0.75)
        formula.set_stroke(BLACK, 3, background=True)
        formula.to_edge(LEFT, buff=MED_SMALL_BUFF)
        formula_brace = Brace(formula[1:], UP)
        formula_words = formula_brace.get_text("Sum of\\\\rotations")
        formula_words.set_stroke(BLACK, 3, background=True)
        #randy = Randolph()
        #randy.to_corner(DL)
        #randy.look_at(formula)
        self.play(FadeOut(real_words),FadeOut(real_arrow),)
        self.play(FadeIn(v1),FadeIn(v2),FadeIn(circle),FadeIn(ghost_v1),FadeIn(ghost_v2),)
        self.wait(3)
        self.play(FadeInFromDown(formula))
        self.play(GrowFromCenter(formula_brace),FadeIn(formula_words),)
        self.wait(2)
        #self.play(FadeIn(randy))
        #self.play(randy.change, "pleading")
        #self.play(Blink(randy))
        #self.wait()
        #self.play(randy.change, "confused")
        #self.play(Blink(randy))
        #self.wait()
        #self.play(FadeOut(randy))
        #self.wait(20)
    def get_complex_plane(self):
        plane = ComplexPlane(**self.complex_plane_config)
        plane.add_coordinates()
        plane.label = TextMobject("Complex plane")
        plane.label.scale(1.5)
        plane.label.to_corner(UR, buff=MED_SMALL_BUFF)
        return plane

生成した動画

以上。