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95 lines
2.7 KiB
95 lines
2.7 KiB
3 months ago
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from manim import *
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class SineCurveUnitCircle(Scene):
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# contributed by heejin_park, https://infograph.tistory.com/230
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def construct(self):
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self.show_axis()
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self.show_circle()
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self.move_dot_and_draw_curve()
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self.wait()
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def show_axis(self):
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x_start = np.array([-6, 0, 0])
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x_end = np.array([6, 0, 0])
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y_start = np.array([-4, -2, 0])
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y_end = np.array([-4, 2, 0])
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x_axis = Line(x_start, x_end)
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y_axis = Line(y_start, y_end)
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self.add(x_axis, y_axis)
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self.add_x_labels()
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self.origin_point = np.array([-4, 0, 0])
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self.curve_start = np.array([-3, 0, 0])
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def add_x_labels(self):
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x_labels = [
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MathTex("\\pi"), MathTex("2 \\pi"),
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MathTex("3 \\pi"), MathTex("4 \\pi"),
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]
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for i in range(len(x_labels)):
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x_labels[i].next_to(np.array([-1 + 2 * i, 0, 0]), DOWN)
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self.add(x_labels[i])
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def show_circle(self):
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circle = Circle(radius=1)
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circle.move_to(self.origin_point)
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self.add(circle)
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self.circle = circle
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def move_dot_and_draw_curve(self):
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orbit = self.circle
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origin_point = self.origin_point
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dot = Dot(radius=0.08, color=YELLOW)
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dot.move_to(orbit.point_from_proportion(0))
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self.t_offset = 0
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rate = 0.25
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def go_around_circle(mob, dt):
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self.t_offset += (dt * rate)
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# print(self.t_offset)
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mob.move_to(orbit.point_from_proportion(self.t_offset % 1))
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def get_line_to_circle():
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return Line(origin_point, dot.get_center(), color=BLUE)
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def get_line_to_curve():
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x = self.curve_start[0] + self.t_offset * 4
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y = dot.get_center()[1]
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return Line(dot.get_center(), np.array(
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[x, y, 0]), color=YELLOW_A, stroke_width=2)
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self.curve = VGroup()
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self.curve.add(Line(self.curve_start, self.curve_start))
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def get_curve():
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last_line = self.curve[-1]
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x = self.curve_start[0] + self.t_offset * 4
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y = dot.get_center()[1]
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new_line = Line(last_line.get_end(), np.array(
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[x, y, 0]), color=YELLOW_D)
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self.curve.add(new_line)
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return self.curve
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dot.add_updater(go_around_circle)
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origin_to_circle_line = always_redraw(get_line_to_circle)
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dot_to_curve_line = always_redraw(get_line_to_curve)
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sine_curve_line = always_redraw(get_curve)
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self.add(dot)
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self.add(
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orbit,
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origin_to_circle_line,
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dot_to_curve_line,
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sine_curve_line)
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self.wait(8.5)
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dot.remove_updater(go_around_circle)
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