Draw line through dots

[erwindenboer]

Hello,

For differentiation, I want to draw a line which goes through two dots. For now, I can draw a line which ends at two dots. Is there something possible which does this?

[kilacoda-old]

You could try to do what you're doing and add multiples of LEFT and RIGHT to each endpoint of the line:

Line(start=p1 +LEFT, end=p2+RIGHT)

EDIT: See last few replies to this thread for the real solution.

[erwindenboer]

Is there someone who has an idea? @kilacoda @hydrobeam

[kilacoda-old]

@erwindenboer Something like this?

scriptoutput.2.mp4

I just applied .scale(4) to line_0 in its definition and the updater

[erwindenboer]

@kilacoda That's exactly what I mean. Thank you! Is it also possible to let the line stop at the borders of the screen? Otherwise, I need to use a large number (e.g. .scale(90000)). Unfortunately, I can't mark this reaction as an answer. But I'll mark your first answer as answered.

[erwindenboer]

@kilacoda Can you send your code on how you created this?

[kilacoda-old]

@kilacoda That's exactly what I mean. Thank you! Is it also possible to let the line stop at the borders of the screen? Otherwise, I need to use a large number (e.g. .scale(90000)). Unfortunately, I can't mark this reaction as an answer. But I'll mark your first answer as answered.

You probably don't need that big of a scale factor 😅 , but something in the range of 25-50 should be more than enough.

@kilacoda Can you send your code on how you created this?

Sure, though it's a bit modified from your original manim_presentation based code:

from manim import *

class Begin(Scene):
    def construct(self):
        ax = Axes(
            x_range=[-2, 5, 1],
            y_range=[-5, 5, 1],
            x_length=12,
            y_length=7,
            x_axis_config={"numbers_to_include": np.arange(-2, 6, 1)},
            y_axis_config={"numbers_to_include": np.arange(-5, 6, 1)},
            tips=False
        )

        labels = ax.get_axis_labels()

        f1 = lambda x: x**3-4*x**2+3*x+1

        func_1 = ax.get_graph(f1, color = ORANGE)

        t_0 = ValueTracker(0)
        t_1 = ValueTracker(1)

        dot_0 = Dot(point=ax.coords_to_point(t_0.get_value(), f1(t_0.get_value())), color=PURPLE)
        dot_1 = Dot(point=ax.coords_to_point(t_1.get_value(), f1(t_1.get_value())), color=PURPLE)

        dot_0.add_updater(lambda x: x.move_to(ax.c2p(t_0.get_value(), f1(t_0.get_value()))))
        dot_1.add_updater(lambda x: x.move_to(ax.c2p(t_1.get_value(), f1(t_1.get_value()))))

        line_0 = Line(dot_0.get_center(),dot_1.get_center(), color=PURPLE).scale(4)
        line_0.add_updater(lambda z: z.become(Line(dot_0.get_center(), dot_1.get_center()).scale(4)))

        self.play(FadeIn(ax, func_1, dot_0, dot_1, line_0))
        self.play(t_1.animate.set_value(0.5))
        self.wait()