[49] Update Animation class

UpdateFromFunc class

    def update_from_func(self):
        dot = Dot().to_edge(LEFT)
        label = TextMobject("Hello").next_to(dot,UP)

        def update_func(mob):
            mob.next_to(dot,UP)

        self.play(
            dot.to_edge,RIGHT,
            UpdateFromFunc(label, update_func),
            run_time=5,
        )

 

 

---

 

    def update_from_func2(self):
        dot = Dot().to_edge(LEFT)
        label = TextMobject("Hello").next_to(dot,UP)

        def update_func(mob):
            mob.next_to(dot, UP)

            x = dot.get_center()[0]
            new_label = TextMobject(str(round(x,0))).move_to(mob)

            mob.become(new_label)

        self.play(
            dot.to_edge,RIGHT,
            UpdateFromFunc(label, update_func),
            run_time=5,
        )

 

---

UpdateFromAlphaFunc class

    def watch_alpha_value(self):
        dot = Dot(radius=0.5, color=RED).to_edge(LEFT)
        dot.save_state()
        decimal = DecimalNumber(0).next_to(dot,UP)

        def update_number(mob, alpha):
            mob.set_value(alpha).next_to(dot, UP)

        self.add(dot, decimal)

        self.play(dot.to_edge, RIGHT,
            UpdateFromAlphaFunc(decimal, update_number),
            rate_func=linear,
            run_time=3,
        )

        dot.restore()
        self.play(dot.to_edge, RIGHT,
                  UpdateFromAlphaFunc(decimal, update_number),
                  rate_func=smooth,
                  run_time=3,
        )

        dot.restore()
        self.play(dot.to_edge, RIGHT,
                  UpdateFromAlphaFunc(decimal, update_number),
                  rate_func=there_and_back,
                  run_time=5,
        )

        self.wait()

 

 

---

 

    def update_color_alpha(self):
        dot = Dot(radius=0.5, color=RED).to_edge(LEFT)
        decimal = DecimalNumber(0).next_to(dot,UP)

        def update_number(mob, alpha):
            mob.set_value(alpha).next_to(dot, UP)

        def update_dot_color(mob, alpha):
            mob.set_color(interpolate_color(RED, YELLOW, alpha))

        self.add(dot, decimal)

        self.play(
            dot.to_edge, RIGHT,
            UpdateFromAlphaFunc(decimal, update_number),
            UpdateFromAlphaFunc(dot, update_dot_color),
            rate_func=there_and_back,
            run_time=10,
        )

        self.wait(2)

 

---

UpdateFromAlphaFunc - 

class SquarePointTest(Scene):
    def construct(self):
        square = Square()
        dot = Dot(color=RED).move_to(square.get_start())
        num = DecimalNumber(0).move_to(square)

        self.add(square, dot)
        self.wait()

        def update_dot_pos(mob, alpha):
            mob.move_to(square.point_from_proportion(alpha))

        def update_num_val(mob, alpha):
            num.set_value(alpha)

        self.play(
            UpdateFromAlphaFunc(dot, update_dot_pos),
            UpdateFromAlphaFunc(num, update_num_val),
            run_time=5,
            rate_func=linear,
        )