manim hypocycloid example video

 

 

class HypocycloidSceneComplete(Scene):
    radius=1.5
    color_path=RED
    divisions=[1,2,3,4,5,6,7,8]
    
    def construct(self):

        self.show_animation()


 
    def show_animation(self):
        c = True
        for i in self.divisions:
            r2=self.radius/i
            self.hypo(self.radius,r2,c)
            c = False
        
    def hypo(self,r1,r2,animation):
        # Manim circle
        c1 = Circle(radius=r1,color=BLUE)
        # Small circle
        c2 = Circle(radius=r2,color=YELLOW).rotate(PI)
        c2.align_to(c1,RIGHT)
        c2.start = c2.copy()
        # Dot
        dot = Dot(c2.point_from_proportion(0.5),color=self.color_path)
        # Line
        line = Line(c2.get_center(),dot.get_center()).set_stroke(GREEN,2.5)
        # Path
        path = VMobject(color=self.color_path)
        path.set_points_as_corners([dot.get_center(),dot.get_center()+UP*0.001])
        # Path group
        path_group = VGroup(line,dot,path)
        # Alpha
        alpha = ValueTracker(0)
        
        # If the animation start then shows the animation
        if animation:
            self.play(Create(line),Create(c1),Create(c2),GrowFromCenter(dot))
        else:
            self.remove(self.dot)
            self.add_foreground_mobjects(dot)
            self.play(Create(line),Create(c2))
            self.remove_foreground_mobjects(dot)
            self.add(c1,c2,path)

        # update function of path_group
        def update_group(group):
            l,mob,previus_path = group
            mob.move_to(c2.point_from_proportion(0.5))
            old_path = path.copy()
            old_path.append_vectorized_mobject(Line(old_path.points[-1],dot.get_center()))
            old_path.make_smooth()
            l.put_start_and_end_on(c2.get_center(),dot.get_center())
            path.become(old_path)

        # update function of small circle
        def update_c2(c):
            c.become(c.start)
            c.rotate(TAU*alpha.get_value(),about_point=c1.get_center())
            c.rotate(-TAU*(r1/r2)*alpha.get_value(),about_point=c.get_center())

        path_group.add_updater(update_group)
        c2.add_updater(update_c2)
        self.add(c2,path_group)
        self.play(
                alpha.animate.set_value(1),rate_func=linear              
                )
        self.wait()
        c2.clear_updaters()
        path_group.clear_updaters()
        self.dot = dot
        self.play(FadeOut(path),FadeOut(c2),FadeOut(line))



# don't remove below command for run button to work
%manim -qm -v WARNING HypocycloidSceneComplete