Which examples should be added to the Documentation?

[MrDiver]

Disclaimer

Keep in mind that these examples can be pretty advanced. But a curious mind is not stopped by a difficult example!

Anchor Mode Example

Code for Example

class AttachHandles(VGroup):
    def __init__(self, vm, anchor_color=[RED,YELLOW], handle_color=[BLUE,GREEN], anchor_radius=DEFAULT_DOT_RADIUS, handle_width=DEFAULT_STROKE_WIDTH, **kwargs):
        super().__init__(**kwargs)
        
        def handle_updater(m):
            group = VGroup()
            [a1,h1,h2,a2] = vm.get_anchors_and_handles()
            for i in range(len(a1)):
                group.add(Line(a1[i],h1[i],color=handle_color[0],stroke_width=handle_width))
                group.add(Line(a2[i],h2[i],color=handle_color[1],stroke_width=handle_width))
                group.add(Dot(a1[i],radius=anchor_radius,color=anchor_color[0]))
                group.add(Dot(a2[i],radius=anchor_radius,color=anchor_color[1]))
            m.become(group)

        self.add_updater(handle_updater)


class AnchorModeExample(Scene):
    def construct(self):
        title = Tex("AnchorModeExample").to_edge(UP)
        self.add(title)

        square = Square(3)
        anchors = AttachHandles(square)
        # handles = VGroup().add_updater(lambda m: m.become(VGroup(*[Dot(handle, color=GREEN) for ])))
        self.add(square, anchors)
        self.play(square.animate.change_anchor_mode("smooth"), run_time=2)
        # self.play(square.animate.)
        self.play(square.animate.become(Circle(2,color=WHITE)).change_anchor_mode("jagged"), run_time=2)

Get Subcurve Example

Code for Example

class GetSubcurveExample(Scene):
    def construct(self):
        title = Tex("GetSubcurveExample").to_edge(UP)
        self.add(title)

        squares = VGroup()
        animations = []

        for i in range(4):
            def get():
                square = Square()
                curve = square.get_subcurve(0, 1)
                start, end = ValueTracker(0), ValueTracker(0)
                curve.add_updater(lambda m: m.become(square.get_subcurve(start.get_value(), end.get_value())))
                animation = AnimationGroup(end.animate.set_value(1), start.animate.set_value(1), lag_ratio=i/4+1/4)
                return square,curve,animation
            square,curve,animation = get()
            animations.append(animation)
            squares.add(square)
            self.add(curve)

        squares.arrange_in_grid(rows=2,cols=2, buff=MED_LARGE_BUFF)
        self.play(*animations, run_time=3)
        self.wait()

Movement Example

Code for Example

class MovementExample(Scene):
    def construct(self):
        title = Tex("MovementExample").to_edge(UP)
        self.add(title)

        square = Square()
        self.play(ComplexHomotopy((lambda z,i: (z*(1-i)+(i)*np.sin(z))), square))
        self.play(PhaseFlow(lambda p: np.array([np.sin(p[0]),np.cos(p[1]),0]), square))
        self.wait()

Point from proportion

Code for Example

class PointFromProportionExample(Scene):
    def construct(self):
        title = Tex("PointFromProportionExample").to_edge(UP)
        self.add(title)

        square = Union(Square(), Square().rotate(PI/4), color=BLUE)
        point = Dot().move_to(square.point_from_proportion(0))
        alpha = ValueTracker(0)
        point.add_updater(lambda m: m.move_to(square.point_from_proportion(alpha.get_value())))
        self.add(square, point)
        self.play(alpha.animate.set_value(1), run_time=3)

Repeat Example

Code for Example

class RepeatExample(Scene):
    def construct(self):
        title = Tex("RepeatExample").to_edge(UP)
        self.add(title)


        transforms = []
        repeat_examples = VGroup()

        for i in range(1, 11):
            circle = Circle()
            square = Square()
            label = Tex(f"Repeats: {i}").next_to(circle, DOWN)
            group = VGroup(circle, square, label).scale(0.5)
            self.add(label)
            repeat_examples.add(group)
            transforms.append(TransformFromCopy(circle.repeat(i), square))
        
        repeat_examples.arrange_in_grid(rows=2,cols=5, buff=MED_LARGE_BUFF)
        self.play(*transforms, run_time=4)

Save and Restore

Code for Example

class SaveRestoreExample(Scene):
    def construct(self):
        square = DashedVMobject(Square(),dashed_ratio=1)
        square.save_state()
        self.add(square)
        self.play(square.animate.arrange_submobjects())
        self.play(square.animate.restore())
        self.wait()

Succession Example

Code for Example

class SuccessionExample(Scene):
    def construct(self):
        title = Tex("SuccessionExample").to_edge(UP)
        self.add(title)

        square = Square()
        circle = Circle()
        self.play(Succession(square.animate.become(Circle(2)),circle.animate.shift(UP)))
        self.wait()

Trace Path Example (WIP)

Code for Example

class TracePathExample(Scene):
    def construct(self):
        title = Tex("TracePathExample").to_edge(UP)
        self.add(title)

        xs = np.linspace(0,PI*2,5)
        def f(t):
            return [t,np.cos(t),0]
            # return np.random.random_integers(-2,2,size=3)
        ys = [f(t) for t in xs]
      
        path = PathFromPoints(ys).make_smooth()
        handles = AttachHandles(path)
        offset = ValueTracker(0)
        dots = []
        traces = []

        n = 2
        for i in range(n):
            def get(i):
                dot = Dot().add_updater(lambda m: m.move_to(path.point_from_proportion((offset.get_value()+i/n)%1)))
                trace = TracedPath(lambda : path.point_from_proportion((offset.get_value()+i/n)%1), dissipating_time=0)
                return dot,trace
            dot,trace = get(i)
            dots.append(dot)
            traces.append(trace)
        # square.add_updater(lambda m: m.become(square.animate.trace_path()))
        # self.add(path)
        self.add(dots[0], traces[0], handles)
        self.play(offset.animate.set_value(1), run_time=3, rate_func=linear)
        self.wait()

[GarryBGoode]

Manim could use more examples, but most of these don't feel right.
So, throwing some opinions at it:

• anchor mode: could be useful example, but should be kept simpler. Just a hexagon turning into circle and back, and use the anchor_mode function, not the become(circle).
• get subcurve: could be useful example, but the animation doesn't showcase the essence of the get_subcurve() function. The same effect can be achieved by animation group with lag_ratio or something. I would rather draw a circle, and cut out like the top 25% with subcurve, and shift it slightly.
• Movement: not necessary. An example needs to be simple to understand, and Complex homotopy and Phase flow are not.
• Save and restore: this one's good.
• Succession: I don't think it's necessary, but not bad.
• Trace path: seems to be wrong example. There is a MoveAlongPath() animation that does exactly what you show, without the updater setup.

On the other hand, I'd like to see some VDict examples. Everyone seems to use VGroup all the time, but it can be useful to use dictionary instead, especially when you want to group different mobjects together, eg. text + dots + lines

[MrDiver]

Feel free to just change them as you like and post them in the comment.

[ScholliYT]

Where did you get the PathFromPoints class from? I want to model a polygonal curve (basically a sequence of linear line segments) and this looks like a good starting point.

[uwezi]

The last code without special functions - works in ManimCE 0.18.1 without additional libraries:

class TracePathExample(Scene):
    def construct(self):
        title = Tex("TracePathExample").to_edge(UP)
        self.add(title)

        xs = np.linspace(0,PI*2,5)
        def f(t):
            return [t,np.cos(t),0]
            # return np.random.random_integers(-2,2,size=3)
        ys = [f(t) for t in xs]

        #path = PathFromPoints(ys).make_smooth()
        path = VMobject().set_points_smoothly(ys)
        ps = path.get_anchors_and_handles()
        handles = VGroup(
            *[
                VGroup(
                    Dot(point=ps[0][i], color=RED),
                    Line(ps[0][i],ps[1][i],color=BLUE),
                    Line(ps[2][i],ps[3][i],color=GREEN),
                    Dot(point=ps[3][i], color=YELLOW),
                ) for i in range(len(ps[0]))]
        )
        offset = ValueTracker(0)
        dots = []
        traces = []

        n = 2
        for i in range(n):
            def get(i):
                dot = Dot().add_updater(lambda m: m.move_to(path.point_from_proportion((offset.get_value()+i/n)%1)))
                trace = TracedPath(lambda : path.point_from_proportion((offset.get_value()+i/n)%1), dissipating_time=0)
                return dot,trace
            dot,trace = get(i)
            dots.append(dot)
            traces.append(trace)

        self.add(dots[0], traces[0], handles)
        self.play(offset.animate.set_value(1), run_time=3, rate_func=linear)
        self.wait()